Abstract

Acanthocephala, with 40 known species, is the most diverse genus of the tribe Acanthocephalini, which contains some of the largest species of Coreidae. In this contribution, Acanthocephala guatemalena, A. granulosa, A. luctuosa, A. panamensis, and A. thoracica were resurrected as valid species, and a morphological phylogenetic analysis, using continuous and discrete characters, was performed to test the monophyly of the genus. The analysis was carried out under implied weighting, including 34 species of Acanthocephala as ingroup, and 20 species from other genera of Acanthocephalini and Placoscelini as outgroups. Acanthocephala was recovered as a monophyletic group, and sister of the clade (Spilopleura parensis + S. ochracea). To formalize and show the relationships of the species in Acanthocephala, the subgenera A. (Acanthocephala) and A. (Metapodiessa) were revalidated, and three new subgenera were proposed: A. (Spinipedia) subgen. nov., A. (Contrastata) subgen. nov., and A. (Pronoptera) subgen. nov. Additionally, a detailed redescription of Acanthocephala, a subgeneric key, descriptions and redescriptions for all subgenera, photographs of dorsal and ventral habitus of the type species of each subgenus, and photographs of the diagnostic characters, including male and female genitalia are provided.

Keywords

Acanthocephalini, cladistic, leaf-footed bugs, morphology, taxonomy, true bugs

1. Introduction

Coreidae, commonly known as leaf-footed bugs (Hemiptera: Heteroptera), includes some of the largest and stoutest terrestrial heteropterans. The family has a cosmopolitan distribution and exhibits its highest species richness in tropical regions (Fernandes et al. 2015). It is currently divided into four subfamilies: Pseudophloeinae, Meropachyinae, Hydarinae and Coreinae, with the latter being the most diverse with 32 tribes and 379 genera (CoreoideaSF Team 2025).

The Coreinae genus Acanthocephala Laporte, 1833 is the most speciose within the tribe Acanthocephalini, including 40 species, several of which were described recently (Olivera et al. 2024a, 2024b). The genus Acanthocephala can be recognized by the large body size from 19 mm to 37 mm, drab coloration, never shiny or with metallic reflections, the pronotal disc strongly declivent and tuberculate, the compressed tylus projected between the genae, the spiny and strongly thickened metafemora, and the presence of lanceolate or foliaceus metatibial expansions (Brailovsky 2006; McPherson et al. 2011; Olivera et al. 2024a). These last two characters are conspicuously developed in males, showing a strong sexual dimorphism in most of the species of the genus.

Stål (1870) established two subgenera within Acanthocephala: A. (Metapodius) (subsequently replaced by Metapodiessa Kirkaldy, 1902), comprising six species, and A. (Spilopleura), with a single species. He also assigned three species to the nominotypical A. (Acanthocephala), without designating a placement for the remaining 13 species known at that time. These subgeneric names were used a few times in the literature (Berg 1878; van Duzee 1916; Pennington 1922; Blöte 1938; Froeschner 1988; McPherson et al. 2011), and were listed as synonyms of Acanthocephala in Packauskas (2010) catalog. Recently, Olivera et al. (2023) removed Spilopleura from synonymy and elevated it to generic rank, to accommodate A. parensis (Dallas, 1852), the species originally included by Stål, and A. ochracea Montandon, 1895.

Several cladistic analyses investigated the higher level relationships within Coreidae and the superfamily Coreoidea, but without focusing on generic relationships (Li 1996, 1997; Henry 1997; Li et al. 2016; Weirauch et al. 2018; Forthman et al. 2019; Tian et al. 2023). Forthman et al. (2020) proposed a phylogeny of the subfamily Coreinae using molecular data, whose results are mostly in agreement with the phylogeny based on morphological characters proposed by Li (1997), which found evidence that some tribes of the subfamily are not monophyletic. Forthman et al. (2020) included three most common North American species of Acanthocephala (A. femorata (Fabricius, 1775), A. alata (Burmeister, 1835), and A. thomasii (Uhler, 1872)) along with species from other four Acanthocephalini genera, and recovered the tribe as the sister group of Placoscelini. Da Silva Costa et al. (2020) and da Silva Costa and Campos (2022) studied the phylogenetic relationships on genus level within the Coreinae tribes Spartocerini and Nematopodini, respectively, through a morphology-based analysis, and highlighted, among other characters, the importance of the male genitalia morphology in the delimitation of genera.

In this contribution, the species A. guatemalena Distant, 1881, A. granulosa (Dallas, 1852), A. luctuosa (Stål, 1855), A. panamensis Distant, 1881, and A. thoracica (Dallas, 1852) are resurrected from synonymy. The monophyly of Acanthocephala and its relationships with related genera, based on adult morphological characters are tested. In accordance with the phylogenetic hypothesis obtained, the subgenus A. (Metapodiessa) is re-validated, and three new subgenera are proposed: A. (Spinipedia) subgen. nov., A. (Contrastata) subgen. nov., and A. (Pronoptera) subgen. nov. A key to recognize the subgenera is also provided, as well as photographs of the dorsal and ventral habitus of the type species, and photographs of the diagnostic characters used in the analysis, including male and female genitalia.

2. Material and methods

2.1. Morphological analysis

2.1.1. Specimens studied and collections

Specimens examined in this study correspond to those listed in Olivera et al. (2023), Olivera et al. (2024a, 2024b), and in File S1, and are deposited in the following institutions: (IFML) Instituto Fundación Miguel Lillo, San Miguel de Tucumán, Argentina; (MACN) Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Autonomous City of Buenos Aires, Argentina; (MCZC) Museum of Comparative Zoology, Harvard University, Cambridge, USA; (MGAB) Muzeul Naţional de Istorie Naturală Grigore Antipa, Bucharest, Romania; (MLP) Museo de La Plata, La Plata, Argentina; (MZSP) Museu de Zoologia da Universidade de São Paulo, São Paulo, Brazil; (NHMUK) Natural History Museum, London, England; (NHMW) Naturhistorische Museum Wien, Vienna, Austria; (NHRS) Naturhistoriska riksmuseet, Stockholm, Sweden; (OUMNH) Oxford University Museum of Natural History, Oxford, England; (PUJ) Departamento de Biología, Pontificia Universidad Javeriana, Bogota, Colombia; (MCNZ) Museu de Ciencias Naturais Fundação Zoobotânica do Rio Grande do Sul, Rio Grande do Sul, Brazil; (UNAL) Universidad Nacional de Colombia, Bogota, Colombia; (UNAM) Instituto de Biología, Universidad Nacional Autónoma de México, Mexico City, Mexico; (USNM) National Museum of Natural History, Smithsonian Institution, Washington, D.C., USA; (ZMHB) Zoologisches Museum für Naturkunde, Berlin, Germany; (ZMUC) Zoologisk museum i København, Copenhagen, Denmark.

2.1.2. Morphological examination and photographs

Specimens were examined using Olympus SZX7 and Nikon SMZ1000 stereomicroscopes. Digital images were taken with a Micrometrics 391CU, 3.2m, Accu–Scope digital camera attached to the Nikon SMZ1000 stereomicroscope. Images were stacked using HeliconFocus 6.7.1 software. Dissections of male and female genitalia and the measurements of external morphological characters included in the analysis were performed according to Olivera et al. (2023). The measurements of the parameres were taken as follows: paramere basal shank length: from base of basal shank to base of arm; paramere arm length: from base of arm to apex.

All measurements in this manuscript are given in millimeters (mm) and are expressed as ranges (min–max).

2.1.3. Selection of taxa

As a result of a taxonomic revision, five species of Acanthocephala were revalidated: A. granulosa and A. luctuosa (see A. (Metapodiessa) nomenclatural remarks), A. guatemalena (see A. (Acanthocephala) nomenclatural remarks), and A. panamensis and A. thoracica (see A. (Pronoptera) nomenclatural remarks). In addition, the names A. arcuata [Uhler? 1884], A. hamata Bergroth, 1924, and A. fulvitarsa (Herrich-Schäffer, 1851) were considered as nomina dubia (see Acanthocephala taxonomic remarks) and were not considered for the analysis. For the cladistic analysis, six species of Acanthocephala (A. consobrina (Westwood, 1842), A. equalis (Westwood, 1842), A. guatemalena, A. mercur (Mayr, 1865), A. thoracica, and A. unicolor (Westwood, 1842)) were excluded, as only type material images were available and no specimens could be examined for comparative purposes. Finally, fifty-four species were included in the analysis. The ingroup was composed of 34 species of Acanthocephala, and the outgroup included 20 species, 19 Acanthocephalini species: Cervantistellus guerrerensis Brailovsky and Barrera, 2005, Cleotopetalops bicolor Brailovsky, 1999, Ctenomelynthus coxalis Breddin, 1903, Empedocles tenuicornis (Westwood, 1842), Laminiceps fenestratus (Burmeister, 1835), Leptopetalops gracilis Breddin, 1901, Lucullia flavovittata Stål, 1865, Meluchopetalops banausus Breddin, 1903, Petalops azureus (Burmeister, 1835), P. distinctus Montandon, 1895, P. proletarius Bredin, 1903, P. thoracicus (Thunberg, 1783), P. virago Breddin, 1901, Salapia sp., S. signata (Dallas, 1852), Spilopleura ochracea, S. parensis, Stenometapodus impictus Breddin, 1903, Zygometapodus castaneus (Blöte, 1938); and one Placoscelini: Plaxiscelis fusca Spinola, 1837 as the root of the tree.

2.2. Phylogenetic analysis

2.2.1. Search strategies

A matrix of 103 characters from the external morphology of adults and the female and male genital morphology was constructed (File S2). Continuous characters (from 0–23) were expressed as simple ratios (except for character 0: body length). These characters were treated as additives and rescaled to unit to reduce the influence of large characters on the matrix (Koch et al. 2014; Barão et al. 2020), following the formula:

(min (x): 0.131 and max (x): 37.750)

mean and standard deviation for each structure are given in File S3). Discrete characters (from 24–102), include binary and multistate, these last were treated as non-additive. Characters that could not be observed were treated as missing entries and were indicated in the matrix with a “?”, inapplicable characters were treated as such following the method of Goloboff et al. (2021) and Goloboff (2022a).

The analysis was conducted in TNT v. 1.6 (Goloboff and Catalano 2016), using implied weighting (IW) (Goloboff et al. 2018; Goloboff 2022b). This method uses a concavity function (k) that weights characters against homoplasy (Goloboff 1993). Following the recommendations given by Goloboff et al. (2008) and Goloboff (2022b) for morphological datasets, values of k between 8–12 were used to check the consistency of the groups, and values that weight too strongly against homoplasy were discarded (Goloboff 1995; Goloboff et al. 2018). A heuristic search was performed using a seed of 2,743, 1,000 random addition sequences (RAS), each followed by tree bisection and reconnection (TBR) branch swapping, saving 10 trees per replication. A maximum of 10,000 trees were held in memory. Continuous characters were mapped on the tree, giving the range of optimal states for each ancestral node, using the command nstates (Catalano and Goloboff 2018; Goloboff 2022b). Consistency index (CI) and retention index (RI) were calculated for the tree. As support, GC frequencies were calculated using symmetric resampling with 1,000 replicates and expressed as GC values (Goloboff et al. 2003). Poorly supported groups were collapsed (Goloboff et al. 2018).

2.2.2. List of characters

Continuous characters

0. Body length.

1. Tylus length/eye width.

2. Eye width/head length.

3. Ocular distance/head length.

4. Interocular space/ocellar distance.

5. Antenna length/body length.

6. Scape length/antenna length.

7. Pedicel length/antenna length.

8. Basiflagellomere length/antenna length.

9. Distiflagellomere length/antenna length.

10. Labium length/body length.

11. Labial segment I length/labium length.

12. Labial segment II length/labium length.

13. Labial segment III length/labium length.

14. Labial segment IV length/labium length.

15. Scutellum length/scutellum width.

16. Male, pronotum width at humeral angles/abdomen width.

17. Female, pronotum width at humeral angles/abdomen width.

18. Male, metafemur width/profemur width.

19. Female, metafemur width/profemur width.

20. Metafemur length/metatibia length.

21. Male, metatibia width/metafemur width.

22. Female, metatibia width/metafemur width.

23. Paramere arm length/paramere basal shank length.

Discrete characters

General coloration

24. Body, surface, coloration: without metallic reflections (0); with metallic reflections (1).

Head

25. Head, tylus, dorsal view, shape: like a distinct knob (0); like a strongly compressed plate (1).

26. Head, tylus, apex, lateral view, position to longitudinal axis of head: below or at the same level (0) (Fig. 4D); above (1) (Fig. 4C). [Modified from character 13, da Silva Costa et al. 2020]

27. Antenniferous tubercle, inner margin: conspicuously separated from the tylus (0); almost reaching or reaching the tylus (1).

28. Antennae, scapus, inner margin: without ridge (0); with a ridge (1).

29. Antennae, pedicel, coloration pattern: unicolor (0); bicolor (1).

30. Antennae, basiflagellomere, coloration pattern: unicolor (0); bicolor (1).

31. Antennae, distiflagellomere, coloration pattern: unicolor and concolor with the rest of the antenna (0); bicolor (1); unicolor and contrasting with the rest of the antenna (2).

32. Eye, lateral view, position: never occupying the entire head height (0) (Fig. 4C–F); almost occupying the entire head height (1) (Fig. 4B).

33. Head, postocular region, dorsal view, shape: flat (0); barely raised (1); with a conspicuous callus (2). [Modified from character 12, da Silva Costa and Campos 2022]

34. Head, ocellar tubercles: absent (0); present (1).

Thorax

35. Pronotum, collar: inconspicuous (0); well-developed (1).

36. Pronotum, frontal angles: not produced forward (0); produced forward (1).

37. Pronotum, anterior lobe, decumbent yellowish setae forming a conspicuous patch: absent (0); present (1).

38. Pronotum, anterolateral margin: smooth or slightly crenulated (0) (Fig. 5A, B); tuberculated (1) (Fig. 5C, D).

39. Pronotum, anterolateral margin, tubercles, size: small (0) (Fig. 5D); big and well-developed (1) (Fig. 5C).

40. Pronotum, humeral angles: not expanded (0) (Fig. 5A); expanded (1) (Fig. 5B–D).

41. Pronotum, humeral angles, expansion: barely developed (0) (Fig. 5B, D); conspicuous and well-developed (1) (Fig. 5C, E).

42. Pronotum, humeral angles, shape: obtusely rounded (0); acute (1).

43. Pronotum, humeral angles, spine: absent (0) (Fig. 5A, C, D); present (1) (Fig. 5B).

44. Pronotum, humeral angles, spine, shape: wide and short (0); narrow and elongate (1).

45. Pronotum, humeral angles, height: at level of pronotal disc (0); over pronotal disc (1) (Fig. 5C, E).

46. Pronotum, posterior lobe, tubercles: absent (0); present (1).

47. Pronotum, posterior lobe, tubercles, arrangement: scattered all over the surface (0) (Fig. 11D); abundant all over surface (1) (Fig. 11A–C); only on humeral angles, with smooth anastomosing regions in the posterior area of the disc (2) (Fig. 11E, F).

48. Pronotum, posterolateral margin: smooth (0) (Fig. 5A); tuberculated (1) (Fig. 5B–D).

49. Pronotum, posterolateral margin, tubercles, size: small (0) (Fig. 5B, D); big and well-developed (1) (Fig. 5C).

50. Pronotum, posterior margin, triangular process: absent (0); present (1).

51. Scutellum, coloration: concolorous (0); apex contrastingly yellowish (1); with a wide central yellowish band extending from base to apex (2).

52. Scutellum, base, central tubercles: absent (0); present (1).

53. Scutellum, base: flat (0); raised (1).

54. Scutellum, apex: flat (0); thickened (1).

55. Hemelytra, clavus and corium, texture: entirely punctate (0); punctate on the sides of the veins and on the center of the cells (1).

56. Hemelytra, costal margin, base: unarmed (0); with small tubercles (1) (Fig. 5F).

57. Thoracic pleurae, medial region, decumbent yellowish setae arranged in patches: absent (0); present (1).

58. Mesopleura, tubercles: absent (0); present (1).

59. Metapleura, tubercles: absent (0); present (1).

60. Metapleura, scent gland auricle, anterior lobe, color: pale brown (0); dark brown to black (1); yellowish to orange (2).

61. Metapleura, scent gland auricle, posterior lobe: absent (0); present (1).

62. Metapleura, evaporatorium, color: concolorous or slightly paler (0); yellowish to orange, contrasting (1), with the rest of the metapleura.

63. Male, metapleura, metathoracic acetabulum: not conspicuously projected (0); conspicuously projected (1) (Fig. 11G, I).

64. Mesofemur, dorsal margin, spines or conical setiferous tubercles: absent (0); present (1).

65. Male, metafemur: not conspicuously thickened (0); conspicuously thickened (1).

66. Male, metafemur, anterior margin: not tuberculated (0); tuberculated (1).

67. Male, metafemur, posterior margin: not tuberculated (0); tuberculated (1).

68. Male, metafemur, dorsal margin, spines or conical tubercles: absent (0); present (1).

69. Male, metafemur, dorsal margin, spines or tubercles, arrangement: one row (0); two rows (1).

70. Male, metafemur, dorsal margin, basal tubercle: not conspicuously larger (0); conspicuously larger (1).

71. Male, metafemur, ventral margin, spines, shape: conical (0) (Fig. 6A–C, E); compressed (1) (Fig. 6D).

72. Female, metafemur: not conspicuously thickened (0); conspicuously thickened (1).

73. Protibia, ventral margin: not tuberculated (0); tuberculated (1).

74. Male, metatibia, dorsal margin: not expanded (0); expanded (1).

75. Male, metatibia, dorsal expansion, size: narrow along all its length (0) (Fig. 7E); conspicuously wider on basal third (1) (Olivera et al. 2023: Fig. 7C); wide along all its length (2) (Fig. 7A–D).

76. Male, metatibia, dorsal expansion, apex, shape: straight (0) (Fig. 7D); rounded (1) (Fig. 7A); oblique, ending in acute angle (2) (Fig. 7B, C, E).

77. Male, metatibia, ventral margin, expanded or thickened: absent (0); present (1).

78. Male, metatibia, ventral margin, spines, arrangement: one row (0); two conspicuous separate rows (1).

79. Male, metatibia, posterior margin, conical tubercles: absent (0); present (1).

80. Female, metatibia, dorsal margin, expansion: absent (0); present (1).

81. Female, metatibia, dorsal expansion, size: narrow along all its length (0) (Olivera et al. 2023: Fig. 3D); conspicuously wider on basal third, sinuous or triangular (1) (Fig. 7E); wide along all its length, with a notch in basal third (2) (Fig. 7A–D).

82. Female, metatibia, ventral margin, expansion: absent (0); present (1).

Abdomen

83. Male, connexiva, small spines or tubercles: absent (0); present (1) (Fig. 11H).

84. Male, sternite III, lateral margin, expanded: absent (0); present (1).

85. Male, sternite III, lateral margin, expansion, shape: like a subtriangular projection (0) (Fig. 8A); fold-like expanded (1) (Fig. 8C–E); slightly thickened posteriorly (2) (Fig. 8B).

86. Sternite III, metacoxae, area below, dark or blackish macula: absent (0); present (1).

Female pregenital region

87. Sternite VII, spiracles, position to an imaginary longitudinal line from the posterolateral angle towards sternites VI: external or on the line (0); internal (1). [Character 71, da Silva Costa et al. 2020]

88. Sternite VII, plica, position in relation to the spiracles: anterior or at the same level (0); posterior (1). [Modified from character 73, da Silva Costa et al. 2020]

89. Sternite VII, plica, shape: concave (0); straight (1); convex (2). [Character 76, da Silva Costa et al. 2020]

90. Sternite VII, median lobes: not overlapping (0); overlapping (1). [Character 77, da Silva Costa et al. 2020]

91. Sternite VII, posterolateral angles, length in relation to the first gonocoxae: not reaching (0); reaching (1); surpassing (2).

Female genitalia

92. Paratergite VIII, posterior margin, extension related to the first gonocoxae: not surpassing (0); surpassing (1). [Modified from character 83, da Silva Costa et al. 2020]

93. Spermatheca, duct, dilatation: absent (0); present (1).

94. Spermatheca, duct, dilatation, shape: oval (0) (Fig. 10D); elongated to cylindrical (1) (Fig. 10E).

95. Spermatheca, seminal receptacle, distal region, shape: sinuous or regularly coiled (0); irregularly coiled (1).

96. Spermatheca, seminal receptacle, apex, shape: rounded to oval (0); reniform (1).

Male genitalia

97. Pygophore, ventral view, shape: rounded (0); oval (1).

98. Pygophore, dorsal view, posterodorsal margin, shape: straight or slightly sinuous (0) (Fig. 9C); with a conspicuous median depression (1) (Fig. 9B). [Modified from character 101, da Silva Costa et al. 2020]

99. Paramere, basal shank, inner margin, apex: narrow (0); wide (1).

100. Paramere, arm, size, maximum width: at middle region (0); at base (1); same width along its entire length (2).

101. Paramere, arm, inner margin, median expansion: absent (0); present (1).

102. Aedeagus, conjunctiva, ventral appendages: absent (0); present (1).

3. Results

3.1. Cladistic analysis

The phylogenetic analyses under implied weighting, using k values between 8 and 12, recovered one tree in all instances. Using k values among 8–10, the trees recovered are identical and differ from those recovered using k values of 11 and 12 in the proposed groupings for A. affinis (Walker, 1871), A. apicalis (Westwood, 1842), A. bicoloripes (Stål, 1855), A. concolor (Herrich-Schäffer, 1841), A. dallasi Lethierry and Severin, 1894, A. distanti Olivera et al., 2024, and A. femorata. In trees obtained with k = 8–11, A. apicalis was recovered as sister species of the clade (A. dallasi + A. bicoloripes), and A. distanti was recovered as sister species of A. femorata. But in the tree with k = 12, A. apicalis was recovered as sister species of A. dallasi, and A. bicoloripes as sister of A. femorata. On the other hand, the trees resulted with k = 8–10 the clade (A. distanti + A. femorata) was recovered as sister group of A. affinis, unlike in the tree with k = 11 where this clade was recovered as sister group of A. concolor. To describe the relationships among the species in the genus we used the tree recovered using a k value of 8. The tree has a total fit of 16.53455, CI = 0.697 and RI = 0.310.

According to our results, the genus Spilopleura, clade S. parensis + S. ochracea, is recovered as sister-group of Acanthocephala. This sister group relationship is supported by three synapomorphies: body length (0:0.561–0.563), the ratio paramere arm length/paramere basal shank length (23:0.014–0.015); and one homoplastic character: male lateral margin of the abdominal sternite III expanded (84:1). The GC frequencies calculated for this clade indicate a low support.

The genus Acanthocephala is recovered as monophyletic (Figs 1, 2), and supported by four autapomorphies: one continuous character related to body length (0:0.641-0.647); and three discrete homoplastic characters (posterior lobe of pronotum tuberculated (46:1), and dorsal expansion of the metatibia wide along all its length in males (75:2) and in females (81:2)). The GC frequencies calculated for this clade indicate a low support due to high contradictory information (Figs 1, 2).

Figure 1.

Phylogenetic hypothesis for Acanthocephala Laporte species. Tree recovered from the IW analysis with a kvalue of 8. First part. Apomorphies of discrete characters are depicted on the tree; nonhomoplastic changes are represented as black hexagons, and homoplastic changes as white hexagons. Support values are shown in parentheses as GC frequencies.

Figure 2.

Phylogenetic hypothesis for Acanthocephala Laporte species. Tree recovered from the IW analysis with a kvalue of 8. Continuation. Apomorphies of discrete characters are depicted on the tree; nonhomoplastic changes are represented as black hexagons, and homoplastic changes as white hexagons. Support values are shown in parentheses as GC frequencies.

The resulting topology of our analysis recovered five main groups in Acanthocephala. Clade A (Fig. 1) is comprised of A. gamboensis Olivera et al., 2024, A. carioca Olivera et al., 2024, A. flaviantennata Olivera et al., 2024, A. harryi Olivera et al., 2024, A. latipes (Drury, 1782), A. nigra Olivera et al., A. pleuritica (Costa, 1863), A. rufa Olivera et al., 2024, A. scutellata (Signoret, 1862), and A. spinosa Olivera et al., 2024. It is supported by: the ratios of interocular space/ocellar distance (4:0.027–0.028), antenna length/body length (5:0.2024), pedicel length/antenna length (7:0.001), metafemur length/metatibia length (20:0.021), and metatibia width/metafemur width in males (21:0.026); two homoplastic characters: head in lateral view with the eye almost occupying the entire head height (32:1), dilatation of the spermathecal duct elongated to cylindrical (94:1); and three autapomorphic characters: posterior lobe of pronotum with smooth anastomosing areas and with small tubercles only on humeral angles (47:2), male with apex of the dorsal expansion of the metatibia rounded (76:1), and male with lateral margin of the abdominal sternite III expanded like a subtriangular projection (85:0). In our analysis, A. pleuritica was recovered as sister to the remaining species, supported by the presence of decumbent yellowish setae arranged in patches on the thoracic pleura (57:1), a unique character within this group, and by the yellowish evaporatorium, contrasting with the rest of the metapleura (62:1). The remaining nine species are separated in two clades. One constituted by A. harryi + (A. scutellata + (A. carioca + A. flaviantennata)), supported by the presence of central tubercles on the base of scutellum (52:1), and the clade A. latipes + (A. rufa + (A. gamboensis + (A. spinosa + A. nigra))), supported by the ratio of metatibia width to metafemur width in females (22:0.048–0.050), the presence of decumbent yellowish setae forming a conspicuous patch on anterior lobe of pronotum (37:1), and the pregenital area in females with the plica placed anterior or at the same level than the spiracles (88:0). The GC frequencies values obtained for the clade A indicate a high support for this group due to low contradictory information, although the support values for the internal nodes were lower.

Clade B (Fig. 1), is comprised by A. heissi Brailovsky, 2006, and is supported by: the ratios of ocular distance/head length (3:0.027), width of pronotum at humeral angles/abdomen width in males (16:0.031) and in females (17:0.027), metafemur width/profemur width in males (18:0.089–0.092), and metatibia width/metafemur width in females (22:0.051); five homoplastic characters: apex of the tylus in lateral view above to longitudinal axis of head (26:1), height of the humeral angles over the pronotal disc (45:1), posterolateral margins of pronotum with big and well developed tubercles (49:1), inner margin of the basal shank of the paramere wide at apex (99:1), arm of the paramere with the same width along its entire length (100:2); and two autapomorphic characters: ventral margin of the protibia tuberculated (73:1), and lateral margin of the abdominal sternite III in males slightly thickened posteriorly (85:2).

Clade C (Fig. 2), including A. thomasii, is supported by: the ratios, tylus length/eye length (1:0.046–0.053), ocular distance/head length (3:0.020–0.022), antenna length/body length (5:0.014), scutellum length/scutellum width (15:0.023), pronotum width at humeral angles/abdomen width in males (16:0.024–0.025) and in females (17:0.020); and two homoplastic characters: base of scutellum with two central tubercles (52:1), and posterior margin of metatibia in males with conical tubercles (79:1).

Clade D (Fig. 2), is composed by A. alata, A. brunnea Olivera et al., 2024, A. declivis (Say, 1832), A. macrotuberculata Olivera et al., 2024, A. maculata Olivera et al., 2024, A. panamensis, A. pilosa Olivera et al., 2024, and A. pittieri Montandon, 1895, and it is supported by: body length (0:0.784–0.785), and the ratio metatibia width/ metafemur width in males (21:0.020); two discrete homoplastic characters: height of the humeral angles over the pronotal disc (45:1), posterolateral margins of pronotum with big and well developed tubercles (49:1); and three discrete autapomorphic characters: anterolateral margins of pronotum with big and well developed tubercles (39:1), expansion of the humeral angles conspicuous and well developed (41:1), and male with dorsal expansion of the metatibia straight (76:0). In our analysis the clade D is separated in the subclade A. declivis + A. alata, supported by the ratios of metafemur width to profemur width in males (18:0.054–0.066), and metatibia width to metafemur width in males (21:0.021–0.029); and three discrete homoplastic characters; the posterior lobe of pronotum with scattered tubercles all over surface (47:0); the spines of the ventral margin of metafemur in males flat or lateral compressed (71:1); and the posterior margin of the paratergite VIII not surpassing the first gonocoxae (92:0). The subclade A. brunnea + (A. pilosa + (A. pittieri + A. panamensis + (A. macrotuberculata + A. maculata))) is supported by the ratios of width of pronotum at humeral angles to abdomen width in females (17:0.031), and width of metafemur to width of profemur in females (19:0.064); and by one discrete homoplastic character: presence of two central tubercles at base of scutellum (52:1). The GC frequencies values obtained for the clade D indicate a high support for this group, although the support values for the internal nodes were lower.

Clade E (Fig. 2), including A. affinis, A. angusta Olivera et al., 2024, A. angustipes (Westwood, 1842), A. apicalis, A. bicoloripes, A. concolor, A. dallasi, A. distanti, A. femorata, A. granulosa, A. latiantennata Olivera et al., 2024, A. luctuosa, A. terminalis (Dallas, 1852) and A. surata (Burmeister, 1835), is supported by: body length (0:0.620–0.629), and the ratios, metatibia width/metafemur width in males (21:0.014–0.017), paramere arm length/paramere basal shank length (23:0.017–0.019); and two discrete homoplastic characters: male with dorsal expansion of the metatibia narrow along all the tibia (75:0) and female with dorsal expansion of the metatibia conspicuously wider on basal third (81:1). In our analysis, the clade E is separated into two main groups. The first one, with the smallest species includes (A. angusta + A. terminalis) + (A. apicalis + (A. dallasi + A. bicoloripes)) is supported by body length (0:0.613–0.617), the ratio of labium length to body length (10:0.005), and the ratio of metafemur width to profemur width in females (19:0.043–0.046). The second one, including A. latiantennata + (A. angustipes + (A. concolor + (A. surata + A. granulosa + A. luctuosa + (A. affinis + (A. distanti + A. femorata))))), is supported by the ratio of tylus length to eye width (1:0.045) and the ratio of pronotum width at humeral angles to abdomen width in males (16:0.024). The GC values calculated for the clade E and the internal nodes are low, indicate a low support due to high contradictory information.

The resulting topology of our analysis, comprising five main clades within Acanthocephala, supports the monophyly of the genus and indicates that the subgeneric division proposed by Stål (1870) was appropriate. Therefore, we resurrected the subgenera A. (Acanthocephala) and A. (Metapodiessa) corresponding to clades A and E in our analysis, respectively, and we also describe three new subgenera: A. (Spinipedia) subgen. nov., corresponding to clade B, A. (Contrastata) subgen. nov., corresponding to clade C, and A. (Pronoptera) subgen. nov., corresponding to clade D.

3.2. Taxonomy

Acanthocephala Laporte, 1833

Figures 3A–E, 4A–F, 5B–F, 6A–E, 7A–E, 8A–E, 9A–E, 10A–E, 11A–F

Acanthocephala Laporte, 1833, 29 [gen. nov.; type species: Lygaeus compressipes Fabricius, 1803]. — Stål, 1870: 9: 149. — Distant, 1881: 117. — Uhler, 1886: 10. — Lethierry and Severin, 1894: 2: 30. — Bergroth, 1913: 128. — Van Duzee, 1914: 46: 378. — Van Duzee, 1917: 85. — Pennington, 1922: 5: 125. — Parshley, 1923: 34: 747. — Blatchley, 1926: 213. — Deay, 1928: 18: 375. — Blöte, 1938: 275. — Torre-Bueno, 1941: 21: 46. — Mead, 1971: 113: 2. — Hoffman, 1975: 105: 11. — Slater and Baranowski, 1978: 58. — Baranowski and Slater, 1986: 12: 8. — Froeschner in Henry and Froeschner, 1988: 73. — Froeschner, 1999: 61: 34. — Arnett, 2000: 254. — Maw et al., 2000: 132. — Brailovsky, 2006: 19: 250. — Packauskas, 2010: 5: 13. — McPherson et al., 2011: 30. — Maes et al., 2024: 6. — Olivera et al., 2024a: 46 (12): 286. — Olivera et al., 2024b: 7 (1): 35. — Serna-Muñoz and Wolff, 2024: 5459 (1): 10. — CoreoideaSF Team, 2025: http://coreoidea.speciesfile.org [on-line catalog].

Diactor Burmeister, 1835: 333 [unnecessary replace name to Acanthocephala Laporte].

Metapodius Westwood, 1842: 2: 4 [unnecessary replace name to Acanthocephala Laporte and Diactor Burmeister]. — Dallas, 1852: 2: 378. — Stål, 1867: 24: 541. — Walker, 1871: 4: 46.

Metapodus: Herrich-Schäffer, 1850: 126 [incorrect spelling].

Metopodus [incorrect spelling]: Amyot and Serville, 1843: 193.

Type species.

Lygaeus compressipes Fabricius, 1803 by original designation [ = A. latipes (Drury, 1782)].

Diagnosis.

Medium to large size species (body length 20.00–38.00mm), ranging from pale brown, reddish brown to almost black, but never with metallic reflections. Pronotal disc punctate and tuberculated, humeral angles expanded. Apex of scutellum thickened or with an apparent callosity. Metathoracic acetabulum unarmed. Metafemur strongly incrassate, particularly in males. Metatibia conspicuously expanded.

Redescription.

MALE. General: Medium to large size species, body length 20.00–38.00 mm. General color pale brown to black, dull, never with metallic reflections. — Head: Dorsally flat, lateral margins parallel (Fig. 4A). Tylus sharply pointed, projecting beyond the juga as a compressed plate (Fig. 4A–F). Juga globose, not visible from above, flexed below antenniferous tubercles (Fig. 4B–F). Post-tylar depression visible. Preocellar pits deep. Eyes hemispherical, globose, and protuberant; postocular region barely raised, visible in dorsal view. Ocelli rounded, ocellar tubercles present. Bucculae subtriangular, subrectangular, or rounded to oval, extending posteriorly beyond the anterior third of eyes, but never surpassing them (Fig. 4B–F). Antenniferous tubercles broad, oblique at apex (Fig. 4A). Antennae variable in length; scape cylindrical, stout and slightly curved outwards, simple or with inner side longitudinally ridged; pedicel and basiflagellomere cylindrical; distiflagellomere elongate and narrowly fusiform. Antennomeres decreasing in length from scape to basiflagellomere, distiflagellomere always the longest. Labium variable in length, at most surpassing mesocoxae; labial segment I longest, labial segment IV shorter, labial segments II and III subequal. — Thorax: Pronotum trapezoidal, steeply declined anteriorly; with a distinct collar, frontal angles blunt (Fig. 5B, D); anterior lobe smooth, unarmed or with one or two pairs of small central tubercles, calli almost flat, with a conspicuous longitudinal depression between them; anterolateral margins straight, crenulate or tuberculated; posterior lobe punctate and tuberculated; humeral angles slightly to conspicuously expanded, with or without a spine; posterolateral margins tuberculate or spined; triangular processes present or not. Scutellum punctate and transversely striated; basal region elevated, unarmed or with two small medial tubercles; lateral margins thickened; apex thickened or callouse, paler or yellowish. Thoracic pleura smooth or tuberculated, episterna striated, epimera punctate; metathoracic scent gland auricle well developed, lobes of auricle rounded or elongate, posterior lobe reduced; evaporative area well developed, striated or slightly punctate; supracoxal area of metapleura incrassate posteriorly or not. Prosternum with a deep concavity; mesosternum flat, with an anterior projection; metasternum flat. Hemelytra: extending beyond the apex of abdomen; clavus and corium punctate, with decumbent yellowish setae on punctures, costal margin unarmed or with small setiferous tubercles; membrane glabrous or with scattered short decumbent yellowish setae next to veins. Legs: Coxae rounded and setose. Trochanters tuberculate or unarmed ventrally. Pro- and mesofemora cylindrical and slender, always armed ventrally, with one or two rows of spines or setiferous tubercles that become larger towards the apex. Mesofemur with anterior, dorsal and posterior margins unarmed or with spines or setiferous tubercles. Metafemur thickened, laterally compressed. Anterior and posterior margins unarmed or tuberculated. Dorsal margin with two rows of conical setiferous tubercles. Ventral margin with one row of conical or compressed to flat spines that become larger towards the middle and decrease towards the apex, or that become slightly larger towards the apex; and with one row of smaller conical tubercles that become larger towards the apex; both rows ending on an apical flat dentate projection. Pro- and mesotibiae cylindrical with the distal third almost quadrangular, with semierect yellowish setae over the entire surface, thicker and darker on the margins at apical third. Protibiae unarmed or ventrally spined. Mesotibia unarmed. Metatibia with decumbent and semierect yellowish setae over the entire surface, apex with a crown of stiff setae; dorsal and ventral margins expanded. Metatibial dorsal expansion wide along the entire length of the tibia (Fig. 7A–D), or slightly sinuous or lanceolate, narrowing towards the apex (Fig. 7E); unarmed or tuberculated apically; ventral expansion slightly developed to inconspicuous, lanceolate or convex, restricted to basal third, from where it abruptly narrows, with one row of conical irregular setiferous tubercles that become larger to the apex, basally forming two rows of small tubercles. Tarsomere I as long as the length of the tarsomeres II and III combined; tarsomeres II and III sub-equal. — Abdomen: Connexiva smooth. Lateral margin of abdominal sternites III-IV simple or expanded, developed in three different forms: Type I: sternite III fold-like expanded, segment IV similar expanded or not (Fig. 8C–E), Type II: sternite III expanded in a subtriangular projection, posterior segments never expanded (Fig. 8A); Type III: sternites slightly expanded at posterior margin, segment III and IV more developed (Fig. 8B). Sternites with decumbent and semierect yellowish setae; lateral areas with rugosities or punctures around spiracles; spiracles well developed and closer to the anterior margin of abdominal sternites. Male genitalia: Pygophore globose, dorsal aperture rounded to oval, with or without parandria (Fig. 9B, C); dorsal margin straight to convex and declivent posteriorly in lateral view (Fig. 9A); posterodorsal margin straight or slightly sinuous to rounded, simple or with a median depression (Fig. 9B, C); transversal wall of pygophore short. Parameres (Fig. 9D): basal shank wide, narrowing at middle or at the joint with the arm in lateral view, inner margin simple or expanded; arm perpendicular to basal shank, wide and slightly concave, narrowing to apex, ending in a downwardly directed apical dentiform process. Aedeagus (Fig. 9E): Phallosoma membranous and wide, basal region and lateral margins partially or totally sclerotized; conjunctiva membranous, with a pair of small ventral well sclerotized appendages that arise from the apex of two well-developed digitiform membranous sacs, and with two pairs of dorsal appendages: dorsal appendages I well sclerotized, large, broad and flat and lobulated apically; dorsal appendages II small and membranous, posterior to the dorsal sac. Dorsal sac of conjunctiva large and membranous. Vesica well sclerotized, coiled, with almost two coils. Ejaculatory duct basally coiled, apically straight or hook-shaped. FEMALE. Structure and color similar to male, except for: Metafemur flattened and less developed than in males (Fig. 6A–E); ventral margin with one row of flat spines and one row of smaller conical tubercles that become larger towards the apex, ending on an apical flat dentate projection. Expansions of the metatibia more developed than in males (Fig. 7A–E); dorsal expansion widely dilated, or sinuous and foliaceus, more developed than males, unarmed or tuberculated apically; ventral expansion convex on basal third, and abruptly constricted and running parallel to the apex, unarmed or with one row of conical irregular setiferous tubercles that become larger to the apex. Female genitalia: Sternum VII with plica and fisura present, median lobes well developed (Fig. 10A). First gonocoxae large and triangular, distal angle rounded, proximal region of the outer lateral margin with well-developed dorsal apodeme (Fig. 10B). First gonapophysis elongate, digitiform, inner region of the distal third weakly sclerotized and with short and thick peg-like setae (Fig. 10B), first ramus well sclerotized, straight or slightly curved. Second gonocoxa elongate and narrow in the middle (Fig. 10C). Second gonapophysis elongate and well sclerotized, thickened distal region with a wide lateral tooth (Fig. 10B), second ramus well sclerotized, basally curved. Spermatheca of Type III, subtype D (Pluot-Sigwalt and Moulet 2020) (Fig. 10D, E): Seminal receptacle tubular, sinuous and apically oval or globose; intermedian zone straight, distal region with a well sclerotized and pigmented flange (distal flange), median region (flexible zone) straight, unsclerotized and unpigmented, proximal region with a slightly pigmented flange (proximal flange); spermathecal duct short, with a dilation with thickened and strongly pigmented walls.

Figure 3.

Acanthocephala spp., dorsal habitus of type species and labels. A A. (Acanthocephala) latipes (Drury, 1782), male syntype, photographed by Laurence Livermore (© Zoologisk museum i København), original photo cropped and contrast adjusted, made available by Natural History Museum of Denmark Zoological Museum of Copenhagen under Creative Commons Attribution 3.0, International Public License, CC BY-NC 3.0; B A. (Spinipedia) heissi Brailovsky, 2006, male paratype; C A. (Contrastata) thomasii (Uhler, 1872), male syntype; D A. (Pronoptera) alata (Burmeister, 1835), male syntype, photographed by Laurence Livermore, original photo cropped and contrast adjusted; E A. (Metapodiessa) femorata (Fabricius, 1775), male syntype, original photo cropped and contrast adjusted (© The Trustees of the Natural History Museum, London (Banks collection)). Scale bar: 10 mm (A–E).

Figure 4.

Acanthocephala spp., head. A Dorsal view, A. (Acanthocephala) latipes (Drury, 1782); B–F Lateral view. B A. (Acanthocephala) latipes; C A. (Spinipedia) heissi Brailovsky, 2006; D A. (Contrastata) thomasii (Uhler, 1872); E A. (Pronoptera) alata (Burmeister, 1835); F A. (Metapodiessa) femorata (Fabricius, 1775). Abbreviations: bu, buccula; ju, juga; mxp, maxillary plate; ty, tylus. Asterisks indicate the apex of the tylus above (char. 26:1) and below (char. 26:0) to the longitudinal axis of the head in distal view. Scale bar: 1 mm (A–F).

Figure 5.

Acanthocephalini spp. A–D Dorsal view of pronotum. A Ctenomelynthus coxalis Breddin, 1903; B Acanthocephala (Acanthocephala) latipes (Drury, 1782); C A. (Pronoptera) panamensis Distant, 1881; D A. (Metapodiessa) femorata (Fabricius, 1775); E Caudal view of pronotum, A. (Pronoptera) panamensis; F Spines of the costal margin of hemelytra, A. (Pronoptera) panamensis. Abbreviations: alm, anterolateral margin of pronotum; cm, costal margin of hemelytra; ha, humeral angles of pronotum; has, spine of humeral angles of pronotum; plm, posterolateral margin of pronotum. Scale bars: 1 mm (A); 2 mm (B–F).

Figure 6.

Acanthocephala spp., male and female metafemur. A A. (Acanthocephala) latipes (Drury, 1782); B A. (Spinipedia) heissi Brailovsky, 2006; C A. (Contrastata) thomasii (Uhler, 1872); D A. (Pronoptera) alata (Burmeister, 1835); E. A. (Metapodiessa) femorata (Fabricius, 1775). Scale bar: 5 mm (A–E).

Figure 7.

Acanthocephala spp., male and female metatibia. A A. (Acanthocephala) latipes (Drury, 1782); B A. (Spinipedia) heissi Brailovsky, 2006; C A. (Contrastata) thomasii (Uhler, 1872); D A. (Pronoptera) alata (Burmeister, 1835); E A. (Metapodiessa) femorata (Fabricius, 1775). Abbreviations: de, dorsal expansion of the metatibia; ve, ventral expansion of the metatibia. Scale bar: 5 mm (A–E).

Figure 8.

Acanthocephala spp., male abdominal expansion. A A. (Acanthocephala) latipes (Drury, 1782); B A. (Spinipedia) heissi Brailovsky, 2006; C A. (Contrastata) thomasii (Uhler, 1872); D A. (Pronoptera) alata (Burmeister, 1835); E A. (Metapodiessa) femorata (Fabricius, 1775). Abbreviations: II, abdominal sternite II; III, abdominal sternite III; IV, abdominal sternite IV; V, abdominal sternite V; VI, abdominal sternite VI. Arrows indicate the expansion of the abdominal segments. Scale bar: 2 mm (A–E).

Figure 9.

Acanthocephala spp., male genitalia. A, B Pygophore, A. (Spinipedia) heissi Brailovsky, 2006. A Lateral view; B dorsal view; C–E A. (Acanthocephala) latipes (Drury, 1782). C Pygophore, dorsal view; D Right paramere, lateral views; E Aedeagus dorsal and ventral views. Abbreviations: ar, arm of paramere; bsh, basal shank of paramere; dap1, first dorsal appendage of conjunctiva; dap2, second dorsal appendage of conjunctiva; dm, dorsal margin of pygophore; do, dorsal opening of pygophore; ds, dorsal sac of conjunctiva; ejd, ejaculatory duct; end, endosoma; gp, gonoporal process; im, inner margin of paramere; om, outer margin of paramere; pdm, posterodorsal margin of pygophore; pha, phallobase; vap, ventral appendage of conjunctiva; vs, vesica. Scale bar: 0.50 mm (A–E).

Figure 10.

Acanthocephala spp., female genitalia. A–D A. (Acanthocephala) latipes (Drury, 1782). A Abdomen ventral view, details of pregenital and genital segments; B First gonocoxa and gonapophysis; C Second gonocoxa and gonapophysis; D Spermatheca; E A. (Spinipedia) heissi Brailovsky, 2006, spermatheca. Abbreviations: da, dorsal apodeme of first gonocoxa; dd, distal duct of spermatheca; df, distal flange; di, dilation of spermathecal duct; fi, fisura; fz, flexible zone; gpI, first gonapophysis; gpII, second gonapophysis; gxI, first gonocoxa; gxII, second gonocoxa; pd, proximal duct of spermatheca; pf, proximal flange; pl, plica; pt8, paratergite VIII; pt9, paratergite IX; raII, second ramus; sr, seminal receptacle; VI, abdominal sternite VI; VII, abdominal sternite VII. Scale bars: 1 mm (A); 0.50 mm (B–E).

Specific taxonomic remarks.

Acanthocephla arcuata [Uhler?] 1884 NOMEN DUBIUM. The name A. arcuata was published in Kingsley (1884: 290) as a captioned figure without text. P. R. Uhler is inferred to be the author, as he is the only entomologist listed on the title page. This species has not been cited since its first appearance, no type material is known, and the illustration is insufficient for identification; it is therefore considered a nomen dubium.

Acanthocephala hamata Bergroth, 1924 NOMEN DUBIUM. Bergroth (1924) described Acanthocephala hamata from “Brasilia” with only a brief description of one female, which was deposited in the Museo Paulista, Sao Paulo, Brazil. The type material is lost, and the description is too general to diagnose the species, and no specimens can be reliably assigned; besides this name was cited only in one catalog (Packauskas 2010) since its publication, therefore we considered this species as a nomen dubium.

Acanthocephala fulvitarsa (Herrich-Schäffer, 1851) NOMEN DUBIUM. Herrich-Schäffer (1851) published the name Meatapodius fulvitarsus with a brief diagnosis, based in a single specimen that was deposited in the Zoologische Staatssammlung München, Munich, Germany, and since then the species was only cited in few catalogues from French Guiana. Unfortunately, the type material is lost, and the published diagnosis is insufficient to identify the species, hence we considered it as a nomen dubium.

Key to subgenera of Acanthocephala Laporte

1 Dorsal expansion of the metatibia narrow along almost all the tibia, and lanceolate or slightly sinuous in males (Fig. 7E); dorsal expansion of the metatibia wider at apical two thirds, foliaceus and sinuous, or triangular in females (Fig. 7E)	*A. (Metapodiessa) Kirkaldy*
1’ Dorsal expansion of metatibia in both sexes similar in shape, well-developed and widely dilated along all tibia (Fig. 7A–D)	2
2 Humeral angles wide and conspicuously expanded (Fig. 5C, E); apex of the dorsal expansion of the metatibia straight (Fig. 7D)	*A. (Pronoptera) subgen. nov*.
2’ Humeral angles weakly expanded (Fig. 5B, D); apex of the dorsal expansion of the metatibia rounded or oblique	3
3 Protibia ventrally spined	*A. (Spinipedia) subgen. nov*.
3’ Protibia unarmed	4
4 Apex of the dorsal expansion of the metatibia oblique in males (Fig. 7C) and rounded in females (Fig. 7C); lateral margin of abdominal sternite III fold-like expanded in males (Fig. 8C)	*A. (Contrastata) subgen. nov*.
4’ Apex of the dorsal expansion of the metatibia rounded in both sexes (Fig. 7A); lateral margin of abdominal sternite III expanded like a subtriangular projection in males (Fig. 8A)	*A. (Acanthocephala) Laporte*

Acanthocephala (Acanthocephala) Laporte, 1833

Figures 3A, 4A–B, 5B, 6A, 7A, 8A, 9C–E, 10A–D, 11E–F

Acanthocephala (Acanthocephala) Laporte, 1833: 29. — Stål, 1870: 9: 149. — Pennington, 1922: 5: 126. — Blöte, 1938: 275.

Type species.

Lygaeus compressipes Fabricius, 1803 by original designation [ = A. latipes (Drury, 1782)] (Fig. 3A).

Included species.

A. (Acanthocephala) carioca Olivera et al., 2024

A. (Acanthocephala) equalis (Westwood, 1842)

A. (Acanthocephala) flaviantennata Olivera et al., 2024

A. (Acanthocephala) gamboensis Olivera et al., 2024

A. (Acanthocephala) guatemalena Distant, 1881

A. (Acanthocephala) harryi Olivera et al., 2024

A. (Acanthocephala) latipes (Drury, 1782)

A. (Acanthocephala) nigra Olivera et al., 2024

A. (Acanthocephala) rufa Olivera et al., 2024

A. (Acanthocephala) pleuritica (Costa, 1863)

A. (Acanthocephala) scutellata (Signoret, 1862)

A. (Acanthocephala) spinosa Olivera et al., 2024

Diagnosis.

Medium size species (body length 20.00–29.00 mm). Species with large eyes in relation to the head height. Antennae slender, as long or longer than the body length; scape with inner side longitudinally ridged. Anterior lobe of pronotum unarmed, posterior lobe with small shiny tubercles on humeral angles, partially anastomosed on posterior region. Humeral angles weakly expanded, acute and spined. Dorsal expansion of metatibia wide and well-developed, ending rounded in both sexes. Abdominal expansion of type II, present only in males.

Description.

MALE. General: Slender and medium size species, body length 20.00–29.00 mm. General color brown to black. — Head: Eyes relatively large, almost occupying the entire head height in lateral view (Fig. 4B). Buccula reaching the anterior third of eye. Antennae slender, as long as or longer than the body length. Scape, pedicel, and basiflagellomere with semierect dark stiff setae; distiflagellomere with abundant decumbent yellowish setae and semierect sparse stiff darker setae. Scape longitudinally ridged on inner side; distiflagellomere conspicuously longer than rest of antennal segments, longer than the length of the pedicel and basiflagellomere combined. Labium variable in length, extending to the anterior region of mesosternum to surpassing the mesocoxae. — Thorax: Pronotum (Fig. 5B) with long and erect dark setae, and short decumbent yellowish setae, scattered or forming a conspicuous patch on anterior lobe; anterior lobe and calli unarmed; posterior lobe with small rounded tubercles on humeral angles, partially anastomosed on posterior region (Fig. 11E, F); anterolateral margins slightly crenulate; humeral angles spined and weakly expanded, elevated or not over the pronotal disc; posterolateral margins with small tubercles; triangular processes present. Base of scutellum unarmed or with two small central tubercles. Thoracic pleura never tuberculated; supracoxal area of metapleura incrassate posteriorly. Hemelytra: clavus and corium with punctures along and next to veins and in the center of the cells, veins concolorous or contrasting reddish, costal margin unarmed; membrane glabrous. Legs: Femora with semierect dark setae all over the surface, and erect setae ventrally; with decumbent yellowish setae in some species. Mesofemur with dorsal, anterior and posterior margins unarmed. Ventral margin of metafemur with conical or compressed to flat spines (Fig. 6A). Metatibial dorsal expansion unarmed, widely dilated, wider at basal third, simple or with a notch from where it slightly narrows to expand again to the apex, ending rounded (Fig. 7A); ventral expansion convex, unarmed or tuberculated; anterior and posterior margins always unarmed. Metatarsus contrasting yellowish. — Abdomen: Terga entirely black. Abdominal sternites with expansion of type II: sternite III laterally with a subtriangular expansion (Fig. 8A). FEMALE. Structure and color similar to male, except for: Supracoxal area of metapleural not incrassate. Abdominal sternite expansion absent.

Figure 11.

Acanthocephalini spp. A–F Texture of the dorsal surface of pronotum. A Acanthocephala (Metapodiessa) granulosa (Dallas, 1852); B A. (Pronoptera) macrotuberculata Olivera et al., 2024; C A. (Metapodiessa) bicoloripes (Stål, 1855); D A. (Pronoptera) declivis (Say, 1832); E A. (Acanthocephala) rufa Olivera et al., 2024; F A. (Acanthocephala) carioca Olivera et al., 2024; G Male metathoracic acetabulum, Spilopleura parensis (Dallas, 1852); H Detail of the lateral margin of the male abdominal segments, Cervantistellus guerrerensis Brailovsky and Barrera, 2005; I Male metathoracic acetabulum, Petalops distinctus Montandon, 1895. Abbreviations: mtac, metathoracic acetabulum. Arrows indicate the spines and tubercles of the connexival segments. Scale bar: 1 mm (B–I).

Distribution.

Widely distributed in the New World, known from Central America to southern South America (Argentina, Brazil, Colombia, Costa Rica, Guyana, Jamaica, Surinam, Panama, Peru, and Venezuela (Olivera et al. 2024a, 2024b; Coreoidea Species File 2025).

Specific nomenclatorial remarks.

Acanthocephala guatemalena Distant, 1881 REVALIDATED NAME. Originally described as Acanthocephala declivis var. guatemalena, this species was synonymized under A. declivis by Lethierry and Severin (1894). Posteriorly was regarded as junior synonym of A. alata by Brailovsky (2006), a status retained to the present day. Distant (1881) described and distinguished this variety by the rounded apex of the dorsal expansion of the metatibia, unlike A. declivis (Say) in which is truncated. After examining the type material of these species, we can distinguish A. guatemalena from A. alata and A. declivis by the posterior lobe of pronotum with short, smooth and shiny tubercles partially anastomosed on the posterior region; the humeral angles ending in a subacute spine directed backwards; the unarmed dorsal margin of mesofemur; and the unarmed dorsal expansion of the metatibia with the apex rounded. On the other hand, A. alata and A. declivis present the posterior lobe of pronotum with sparse and small, rounded and not anastomosed tubercles; the humeral angles conspicuously wide and unspined; the dorsal margin of the mesofemur armed with a row of conical setiferous tubercles; and the dorsal expansion of the metatibia tuberculated on the distal third and with the apex straight. Therefore, we remove A. declivis var. guatemalena from synonymy and establish it as a valid species (A. guatemalena stat. nov.) in the subgenus A. (Acanthocephala).

Discussion.

Stål (1870) originally included three species in the subgenus A. (Acanthocephala): A. latipes, A. alata, and A. declivis. However, our cladistic analysis does not support the inclusion of the latter two species, which are herein transferred to A. (Pronoptera). In accordance to our results, we include in the nominotypical subgenus A. (Acanthocephala) the species forming the clade A. Additionally, although A. equalis and A. guatemalena were not included in the phylogenetic analysis, they are assigned to A. (Acanthocephala) based on the presence of the subgeneric autapomorphies, which were assessed from photographs of the type material of these species. This subgenus is easily distinguished as the only one that exhibits a type II abdominal expansion and a wide, well developed dorsal expansion of the metatibia along its entire length in both sexes, with a conspicuously rounded apex.

Acanthocephala (Spinipedia) subgen. nov.

https://zoobank.org/E8209A53-EE45-460F-AFE8-0C9F93F0CCB9

Figures 3B, 4C, 6B, 7B, 8B, 9A, 9B, 10E

Type species.

Acanthocephala heissi Brailovsky, 2006 by present designation (Fig. 3B).

Included species.

A. (Spinipedia) heissi Brailovsky, 2006

Diagnosis.

Medium size species (body length 25.00–27.00 mm). Eyes small in relation to the head height. Antennae stout, as long as the body length; scape simple, never with an inner longitudinal ridge. Anterior lobe of pronotum with one pair of small central tubercles, posterior lobe with short and small rounded tubercles all over its surface. Humeral angles expanded, acuminate and spined. Protibia spined. Dorsal expansion of metatibia in both sexes, wide and well-developed, ending in acute angle. Abdominal expansion type III, present only in males.

Description.

MALE. General: General color dark brown to black. Medium size specimens, body length 25.00–27.00 mm. — Head: Eyes relatively small, never occupying the entire head height in lateral view (Fig. 4C). Antennae stout, as long as the body length. Scape, pedicel, and basiflagellomere with semierect stiff dark setae; distiflagellomere with abundant decumbent yellowish setae and semierect sparse stiff darker setae. Scape simple, not longitudinally ridged on inner side; distiflagellomere shorter than or equal to the combined length of the pedicel and basiflagellomere. Labium short, not reaching the mesocoxae. — Thorax: Pronotum with long and erect dark setae and short decumbent yellowish setae, never forming a conspicuous patch on anterior lobe; anterior lobe with one pair of small central tubercles, posterior lobe with short and small rounded tubercles; anterolateral margins with well-developed conical tubercles; humeral angles spined and expanded, acuminate, ending in a sharp elongate broad spine, elevated over the pronotal disc; posterolateral margins with well-developed tubercles; triangular processes present. Scutellum with decumbent yellowish setae and erect stiff darker setae; base unarmed. Propleura always tuberculated, meso- and metapleurae unarmed; supracoxal area of metapleura incrassate posteriorly; anterior and posterior lobes of metathoracic scent gland auricle elongate, evaporatorium finely punctate. Thoracic sterna with abundant erect dark setae and semierect and decumbent yellowish setae. Hemelytra: clavus and corium with punctures along and next to veins and in the center of the cells, veins concolorous, costal margin unarmed; membrane glabrous. Legs: Femora with decumbent yellowish setae and semierect dark setae all over the surface, and erect setae ventrally. Mesofemur with anterior, posterior and dorsal margins unarmed. Ventral margin of metafemur with conical and slightly compressed spines, but never flat, that becomes larger towards the middle; anterior and posterior margins with small rounded tubercles of irregular size (Fig. 6B). Protibia ventrally spined. Metatibial dorsal expansion widely dilated, wider at basal third, with a notch from where it slightly narrows to the apex, ending in acute angle, with one or two conspicuous teeth apically; ventral expansion inconspicuous and tuberculated (Fig. 7B); anterior and posterior margins always unarmed. Tarsi brown. — Abdomen: Terga with yellowish markings, never entirely black. Abdominal sternites with expansion of type III: sternites III, IV, V and VI slightly laterally expanded at posterior margin (Fig. 8B). FEMALE. Structure and color similar to male, except for: Supracoxal area of metapleura not incrassate. Anterior margin of metafemur unarmed, posterior margin with small apical tubercles. Ventral expansion of metatibia lanceolate and unarmed (Fig. 7B). Abdominal sternites without expansions.

Etymology.

The subgeneric name refers to the ventrally spined protibia of the type species. The gender is feminine.

Distribution.

Known from Central America (Guatemala) and Mexico (Brailovsky 2006; Olivera et al. 2024b).

Discussion.

This subgenus is easily distinguished as the only one that exhibits a type III abdominal expansion and a tuberculate protibia. Consequently, we establish A. (Spinipedia) (clade B) to accommodate A. heissi.

Acanthocephala (Contrastata) subgen. nov.

https://zoobank.org/30DEBF29-6D22-405A-A9AB-0B089C58E3DD

Figures 3C, 4D, 6C, 7C, 8C

Type species.

Metapodius thomasii Uhler, 1872 by present designation (Fig. 3C).

Included species.

A. (Contrastata) thomasii (Uhler, 1872)

Diagnosis.

Stout species, medium to large size (body length 27.00–32.00 mm). Eyes small in relation to the head height. Antennae stout, shorter than the body length; scape simple, not longitudinally ridged. Anterior lobe of pronotum with one pair of small central tubercles, posterior lobe with small, rounded tubercles all over its surface. Humeral angles rounded, weakly expanded, ending acutely but spineless. Dorsal expansion of metatibia wide and well-developed in both sexes, ending acute in males and rounded in females. Male with expansion of abdominal sternites type I, developed only anteriorly in sternite III, sternite IV never expanded.

Description.

MALE. General: General color dark brown to black, with light brown to yellowish contrasting structures. Medium to large size species, body length 27.00–32.00 mm. — Head: Eyes relatively small, never occupying the entire head height in lateral view (Fig. 4D). Buccula reaching the middle third of the eye. Antennae stout, shorter than the body length. Scape, pedicel, and basiflagellomere with semierect stiff dark setae; distiflagellomere with abundant decumbent yellowish setae and semierect sparse stiff darker setae. Scape simple, not longitudinally ridged on inner side; distiflagellomere shorter than the length of the pedicel and basiflagellomere combined. Labium extending to mesocoxae. — Thorax: Pronotum with scattered semierect yellowish setae and short decumbent yellowish setae, never forming a conspicuous patch; anterior lobe with one pair of small central tubercles between calli; posterior lobe with dark and abundant small rounded tubercles; anterolateral margins with well-developed conical tubercles; humeral angles rounded, ending acutely but spineless, weakly expanded, not elevated over the pronotal disc; posterolateral margins with small tubercles; triangular processes present. Scutellum with decumbent yellowish setae; base with two small central tubercles. Propleura tuberculated, meso- and metapleurae unarmed; supracoxal area of metapleura incrassate posteriorly; anterior lobe of metathoracic scent gland auricle rounded, posterior lobe elongate, evaporatorium with conspicuous rugosities. Thoracic sterna with abundant decumbent and semierect yellowish setae. Hemelytra: clavus and corium entirely punctate, veins concolorous, costal margin unarmed; membrane glabrous. Legs: Femora with semierect dark setae all over the surface, and erect setae ventrally. Mesofemur with dorsal, anterior and posterior margins unarmed. Ventral margin of metafemur with conical and compressed spines, but never flat, that becomes larger towards the middle (Fig. 6C); anterior and posterior margins with small rounded tubercles of irregular size. Protibia unarmed. Metatibial dorsal expansion widely dilated, wider at basal third, from where it narrows to the apex, ending in acute angle, with small tubercles apically; ventral expansion slightly lanceolate and tuberculated; anterior margin unarmed; posterior margin with small conical tubercles (Fig. 7C). Pro-, meso- and metatarsi yellowish to orange. — Abdomen: Terga with a central longitudinal yellowish fringe, never entirely black. Abdominal sternites with expansion of type I: sternite III expanded only anteriorly; sternite IV not expanded (Fig. 8C). FEMALE. Structure and color similar to male, except for: Supracoxal area of metapleura not incrassate. Metatibial dorsal expansion wider than in males, with a notch at basal third, ending rounded (Fig. 7C); ventral expansion slightly convex; posterior margin unarmed. Abdominal sternites expansions absent.

Etymology.

The name Contrastata comes from Latin and means contrast, referring to the marked color contrast between the yellow distiflagellomere, tibiae, and tarsi, and the dark body of the type species Metapodius thomasii Uhler, 1872. The gender is feminine.

Distribution.

Known from North America (Mexico and United States (Brailovsky 2006; McPherson et al. 2011)).

Discussion.

Acanthocephala thomasii was included in A. (Metapodiessa) by Van Duzee (1916). Nevertheless, the results of our analysis do not support this hypothesis, and we transfer A. thomasii to A. (Contrastata) n. subgen. (clade C). This new subgenus can be distinguished by the dorsal expansion of the metatibia, which in both sexes is wide and well developed along its entire length. In contrast, in A. (Metapodiessa), the dorsal expansion of the metatibia is narrow and lanceolate in males, and sinuous or triangular in females, being wide only at the basal third and narrowing toward the apex.

Acanthocephala (Pronoptera) subgen. nov.

https://zoobank.org/423278FD-9654-4C96-A839-1D66ED810082

Figures 3D, 4E, 5C, 5E–F, 6D, 7D, 8D

Type species.

Diactor alatus Burmeister, 1835 by present designation (Fig. 3D).

Included species.

A. (Pronoptera) alata (Burmeister, 1835)

A. (Pronoptera) brunnea Olivera et al., 2024

A. (Pronoptera) declivis (Say, 1832)

A. (Pronoptera) macrotuberculata Olivera et al., 2024

A. (Pronoptera) maculata Olivera et al., 2024

A. (Pronoptera) mercur (Mayr, 1865)

A. (Pronoptera) panamensis Distant, 1881

A. (Pronoptera) pilosa Olivera et al., 2024

A. (Pronoptera) pittieri Montandon, 1895

A. (Pronoptera) thoracica (Dallas, 1852)

Diagnosis.

Medium to large size species (body length 27.00–38.00 mm). Eyes small in relation to the head height. Antennae stout, as long as or shorter than the body length; simple, never with inner side longitudinally ridged. Anterior lobe of pronotum unarmed or with one or two pairs of small central tubercles, posterior lobe with rounded tubercles all over its surface. Humeral angles conspicuously expanded, wide, spineless or sharply acute, elevated over the pronotal disc. Dorsal expansion of metatibia wide and well-developed, ending in a straight angle in both sexes. Abdominal expansion of type I; always present in males, sternite III expanded only anteriorly, sternite IV not expanded; absent or present in females.

Description.

MALE. General: Medium to large size species, body length 27.00–38.00 mm. General color brown to black. — Head: Eyes relatively small, never occupying the entire head height in lateral view (Fig. 4E). Buccula extended to the posterior third of the eye. Antennae stout, as long as or shorter than the body length. Scape, pedicel, and basiflagellomere with semierect dark stiff setae always present and with or without decumbent yellowish setae; distiflagellomere with abundant decumbent yellowish setae and semierect sparse darker stiff setae. Scape simple, not longitudinally ridged on inner side; distiflagellomere shorter than or equal to the combined length of the pedicel and basiflagellomere. Labium extending to mesocoxae. — Thorax: Pronotum with long and erect stiff setae and short decumbent yellowish setae, more abundant on anterior lobe, but never forming a conspicuous patch; anterior lobe and calli unarmed, or with one or two pairs of small rounded central tubercles next to collar and between calli; posterior lobe with small to large and well-developed rounded tubercles on all its surface; anterolateral margins with well-developed conical tubercles (Fig. 5C); humeral angles conspicuously expanded, wide and spineless or sharply acute, elevated over the pronotal disc (Fig. 5C, E, F); posterolateral margins with small to well-developed tubercles; triangular processes present. Propleura always tuberculated, meso- and metapleurae unarmed; supracoxal area of metapleura incrassate posteriorly. Hemelytra: clavus and corium entirely punctate, veins concolorous, costal margin unarmed or with one or more small setiferous tubercles (Fig. 5F); membrane glabrous or with scattered short decumbent yellowish setae. Legs: Femora with decumbent yellowish setae and semierect dark setae all over the surface, in some with erect setae ventrally. Mesofemur with anterior margin unarmed, and dorsal and posterior margins unarmed or with small tubercles. Ventral margin of metafemur with conical and slightly compressed laterally spines, but never flat, that becomes larger towards the middle (Fig. 6D); anterior and posterior margins unarmed or with small rounded tubercles of irregular size. Protibia unarmed. Metatibial dorsal expansion well-developed, wider at basal third, from where it slightly narrows to the apex, ending in a straight angle, distal third unarmed or with small setiferous tubercles; ventral expansion inconspicuous and tuberculated (Fig. 7D); anterior and posterior margins always unarmed. Tarsi dark brown or yellowish to orange. — Abdomen: Terga with rounded yellowish macula around scent glands scars, never entirely black. Abdominal sternites with expansion of type I: sternite III expanded only anteriorly; sternite IV not expanded (Type I) (Fig. 8D). FEMALE. Structure and color similar to male, except for: Supracoxal area of metapleura not incrassate. Ventral expansion of metatibia slightly convex on the basal third and abruptly constricted and running parallel to the apex (Fig. 7D). Abdominal sternite expansion absent or present, if it is present less developed than in males.

Etymology.

The suffix -ptera meaning wings or wing-like parts, refers to the wide and wing-like pronotal humeral angles of the species included in this subgenus. The gender is neuter.

Distribution.

Known from North America to northern South America (Brazil, Colombia, Costa Rica, Guatemala, Honduras, Nicaragua, Mexico, Panama, and United States (Brailovsky 2006; McPherson et al. 2011; Olivera et al. 2024a, 2024b; Coreoidea Species File 2025)).

Specific nomenclatorial remarks.

Acanthocephala panamensis Distant, 1881 REVALIDATED NAME. Originally described as Acanthocephala declivis var. panamensis, this species was synonymized under A. declivis by Lethierry and Severin (1894). Posteriorly was regarded as junior synonym of A. alata by Brailovsky (2006), a status retained to the present day. After a comprehensive examination of the type specimens of these names, we recognize A. panamensis as clearly distinguishable from A. declivis and A. alata by the presence of abundant rounded and well developed shiny tubercles irregularly arranged on the posterior lobe of pronotum, the conspicuously acute humeral angles, the presence of two medial rounded tubercles at the base of the scutellum, and the presence of small setiferous tubercles on the basal region of the costal margin of hemelytra. Therefore, we remove A. declivis var. panamensis from synonymy and establish it as a valid species (A. panamensis stat. nov.) in the subgenus A. (Pronoptera).

Acanthocephala thoracica (Dallas, 1852) REVALIDATED NAME. Originally described as Metapodius thoracicus, this species was synonymized under A. alata by Stål (1870). Subsequently, A. alata was synonymized under A. declivis by Distant (1881). Finally, Brailovsky (2006) revalidated A. alata as a valid name, leaving M. thoracicus as its junior synonym. After a detailed examination of the type specimens of the aforementioned names, we observed that the specimen described by Dallas can be distinguished from A. declivis and A. alata specimens by the largest body size; the more acute and elongate humeral angles, ending conspicuously acute and directed backwards; and by the absence of the characteristic central macula in the posterior lobe of the pronotum of A. alata. We remove M. thoracicus from synonymy and re-established it as a valid species in the subgenus A. (Pronoptera).

Discussion.

In accordance with our results, we assign the species in the clade D to the new subgenus A. (Pronoptera). We transfer A. alata and A. declivis from A. (Acanthocephala), and include within it the species A. brunnea, A. macrotuberculata, A. maculata, A. panamensis, A. pittieri, and A. pilosa. In addition, the species A. mercur and A. thoracica, although not included in the phylogenetic analysis, are assigned to A. (Pronoptera) based on the presence of the subgeneric autapomorphies. These autapomorphies were observed from the original description and from photographs of the type material. This new subgenus can be distinguished by the conspicuous expansion of the humeral angles and the dorsal expansion of the metatibia. Although the metatibia is wide and well developed along its entire length in both sexes, similar to A. (Acanthocephala), it differs by having a straight apex. In contrast, the metatibia apex in A. (Acanthocephala) is distinctly rounded.

Acanthocephala (Metapodiessa) Kirkaldy, 1902 REVALIDATED NAME

Figures 3E, 4F, 5D, 6E, 7E, 8E

Acanthocephala (Metapodius) Stål, 1870: 9: 150 [subgen. nov.]. — Blöte, 1938: 20: 276. — Packauskas, 2010: 13 [as synonym of Acanthocephala].

Acanthocephala (Metapodiessa) Kirkaldy, 1902: 137 [new name for Acanthocephala (Metapodius)]. — Pennington, 1922: 5: 127. — Acanthocephala (Metapodiessa): Froeschner in Henry and Froeschner, 1988: 74. — McPherson et al., 2011: 37. —CoreoideaSF Team, 2025: http://coreoidea.speciesfile.org [cat. on-line].

Type species.

Cimex femoratus Fabricius, 1775 by present designation (Fig. 3E).

Included species.

A. (Metapodiessa) affinis (Walker, 1871)

A. (Metapodiessa) angusta Olivera et al., 2024

A. (Metapodiessa) angustipes (Westwood, 1842)

A. (Metapodiessa) apicalis (Westwood, 1842)

A. (Metapodiessa) bicoloripes (Stål, 1855)

A. (Metapodiessa) concolor (Herrich-Schäffer, 1841)

A. (Metapodiessa) consobrina (Westwood, 1842)

A. (Metapodiessa) dallasi Lethierry and Severin, 1894

A. (Metapodiessa) distanti Olivera et al., 2024

A. (Metapodiessa) femorata (Fabricius, 1775)

A. (Metapodiessa) granulosa (Dallas, 1852)

A. (Metapodiessa) latiantennata Olivera et al., 2024

A. (Metapodiessa) luctuosa (Stål, 1855)

A. (Metapodiessa) surata (Burmeister, 1835)

A. (Metapodiessa) terminalis (Dallas, 1852)

A. (Metapodiessa) unicolor (Westwood, 1842)

Diagnosis.

Medium size species (body length 23.00–30.00). Eyes small in relation to the head height. Antennae stout, shorter than the body length; simple, never with inner side longitudinally ridged. Anterior lobe of pronotum unarmed or with one or two pairs of small central tubercles, posterior lobe with rounded tubercles all over its surface. Humeral angles weakly expanded and nearly rounded, obtuse or slightly acute, spineless, not elevated over pronotal disc. Dorsal expansion of metatibia lanceolate or wider and slightly sinuous in males, sinuous or triangular in females, wider to the apex at basal third and narrowing to the apex, ending in acute angle on both sexes. Abdominal expansion of type I, always present in males; absent or present in females, if it is present, only the sternite III is anteriorly expanded.

Description.

MALE. General: Medium size species, body length 23.00–30.00. General color pale brown to dark brown. — Head: Eyes relatively small, never occupying the entire head height in lateral view (Fig. 4F). Buccula usually extended to the posterior third of eye. Antennae stout, shorter than the body length. Scape, pedicel, basi- and distiflagellomere with semierect stiff dark setae and with decumbent yellowish setae. Scape simple, not longitudinally ridged on inner side; distiflagellomere shorter than or equal to the combined length of the pedicel and basiflagellomere. Labium extending to mesocoxae. — Thorax: Pronotum (Fig. 5D) with long and erect stiff dark setae and short decumbent yellowish setae, never forming a conspicuous patch; anterior lobe and calli unarmed, or with one or two pair of small rounded central tubercles next to collar and between calli; posterior lobe with rounded tubercles on all its surface; anterolateral margins with conspicuous conical tubercles; humeral angles spineless, obtuse or acute, nearly rounded and weakly expanded, not elevated over the pronotal disc; posterolateral margins with small tubercles; triangular processes short or absent. Scutellum with abundant decumbent yellowish setae and erect stiff darker setae; base unarmed or with two small central tubercles. Thoracic pleura unarmed or tuberculated; supracoxal area of metapleura incrassate posteriorly; anterior lobe of metathoracic scent gland auricle rounded, posterior lobe elongate, evaporatorium with conspicuous rugosities. Thoracic sterna with abundant, erect, dark setae, and decumbent, yellowish setae. Hemelytra: clavus and corium entirely punctate, veins concolorous, costal margin unarmed; membrane glabrous or with scattered short decumbent yellowish setae. Legs: Femora with decumbent yellowish setae and semierect dark setae all over the surface, and erect setae ventrally. Mesofemur with dorsal margin unarmed, and with anterior and posterior margins unarmed or with small tubercles. Ventral margin of metafemur with conical spines that become larger towards the middle and with a median spine conspicuously larger, or with compressed spines that become slightly larger towards the apex (Fig. 6E); anterior and posterior margins with abundant rounded tubercles of irregular size. Protibia unarmed. Metatibia dorsal expansion slightly developed, lanceolate or slightly sinuous, ending in acute angle, distal third always armed with small setiferous tubercles; ventral expansion lanceolate, slightly developed on basal third to inconspicuous, with one row of conical irregular setiferous tubercles that become larger to the apex (Fig. 7E). Pro-, meso- and metatarsi pale brown to yellowish. — Abdomen: Terga with a longitudinal yellowish fringe or rounded maculae around scent glands scars, never entirely black. Abdominal sternites with expansion of type I: sternite III expanded across the entire margin or expanded only anteriorly; sternite IV expanded only anteriorly, or not expanded (Fig. 8E). FEMALE. Structure and color similar to male, except for: Supracoxal area of metapleura simple or incrassate posteriorly, but less developed than in males. Dorsal expansion of metatibia triangular and developed on basal third, or foliaceus and sinuous, wider to the apex at basal third, simple or with a notch from where it narrows to the apex, ending in acute angle, distal third unarmed or with small setiferous tubercles; ventral expansion convex on basal third, and abruptly constricted and running parallel to the apex (Fig. 7E). Abdominal sternites expansion absent or present, if it is present only the sternite III is expanded anteriorly.

Distribution.

Widely distributed in the New World, known from Central America to southern South America (Argentina, Barbados, Brazil, Canada, Colombia, Costa Rica, Ecuador, French Guiana, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, United States, and Venezuela (Brailovsky 2006; McPherson et al. 2011; Olivera et al. 2024a, 2024b; Coreoidea Species File 2025)).

Specific nomenclatorial remarks.

Acanthocephala granulosa (Dallas, 1852) REVALIDATED NAME. This taxon was originally described as Metapodius granulosus and was synonymized under A. femorata by Barber (1926). After a detailed examination of the type material of both names, we observed that the specimens described by Dallas can be distinguished from A. femorata by having the posterior lobe of the pronotum with abundant and well-developed rounded tubercles, antennae paler than the rest of the body, and the unarmed scutellum, metapleurae, and posterior margin of the mesofemora. In contrast, A. femorata presents the posterior lobe of the pronotum with smaller and sparser tubercles, reddish to brown antennae, and the scutellum, metapleurae, and posterior margin of the mesofemora tuberculated. According to these, we remove from synonymy A. granulosa and re-established it as a valid species in the subgenus A. (Metapodiessa).

Acanthocephala luctuosa (Stål, 1855) REVALIDATED NAME. Originally described as Metapodius luctuosus, this species, was also synonymized under A. femorata by Barber (1926). We examined the type material of these species and we observed that it can be easily distinguished from A. femorata and A. granulosa by the structure of the scape, which is conspicuously broader than the other antennal segments; the coloration pattern of the antennae, which is brown with the distiflagellomere contrastingly yellowish; and by the ornamentation of the pronotum, with the posterior lobe slightly punctate and with small and rounded scattered tubercles. We remove from synonymy A. luctuosa and re-established it as a valid species in the subgenus A. (Metapodiessa).

Discussion.

Stål (1870) included six species in A. (Metapodiessa): A. bicoloripes, A. femorata, A. granulosa, A. luctuosa, A. surata, and A. terminalis. Later, Van Duzee (1916) included A. thomasii (which is transferred to A. (Contrastata) in the present work), and Blöte (1938) included A. consobrina. According to our results, we also include in this subgenus the remaining species forming clade E. In addition, the species A. unicolor, although not included in the phylogenetic analysis, is assigned to A. (Metapodiessa) based on the presence of the subgeneric autapomorphies, which were assessed from photographs of the type specimens. This subgenus can be distinguished by the dorsal expansion of the metatibia, which exhibits distinct sexual dimorphism: in males, the expansion is narrow (lanceolate or slightly sinuous) along its entire length, whereas in females it is wide (sinuous or triangular) only at the basal third, narrowing toward the apex.

4. Discussion and conclusions

This cladistic analysis supports the monophyly of the genus Acanthocephala. This hypothesis is consistent with the subgeneric division proposed by Stål (1870), suggesting that Stål’s classification, despite lacking modern tools, effectively delineated natural groups within the genus. With the current revalidations and the inclusion of the newly described subgenera (Pronoptera, Contrastata, Spinipedia), the classification of Acanthocephala is now integrated into a phylogenetic context.

Taxonomically, Acanthocephala has historically presented a significant challenge, primarily due to the old and often incomplete original descriptions, partial regional keys, and high species richness, all of which have led to numerous synonymies and doubtful or inaccurate identifications. This problem was further compounded by a distinct geographic bias in research focus, as most published work concentrated on North American species, resulting in a poor understanding of the diversity and biology of Central and South American taxa (Gibson and Holdridge 1918; Blatchley 1926; Baranowski and Slater 1986; Froeschner 1988; Eberhard 1998; Brailovsky 2006; McPherson et al. 2011).

The recent works by Olivera et al. (2023, 2024a, 2024b), which described 14 new species and transferred two species to the revalidated genus Spilopleura, show that the rapid increase in species count necessitates an urgent focus on the stability of existing names. Crucially, these studies highlight that the diversity of this Coreidae genus in the Neotropics has been severely underestimated. The present study contributes to this ongoing effort by revalidating five species (A. granulosa, A. luctuosa, A. guatemalena, A. panamensis, and A. thoracica); and by designating three names (A. arcuata, A. hamata, and A. fulvitarsa) as nomina dubia. The latter designations emphasize the persistent challenges presented by old and incomplete descriptions and the loss or deterioration of type specimens. Overall, based on the results of this revision, we formally recognized 40 valid species within Acanthocephala.

While the present work provides a diagnostic key to the subgenera, future studies are required to provide clear and concise re-descriptions of all species currently lacking them, and to develop comprehensive species-level identification keys. Such contributions will be essential to ensure accurate classification, support taxonomic research, and prevent misidentifications. Finally, this framework provides a solid foundation for further investigations into the evolutionary history, biogeography, and species-level delineation of this taxonomically challenging genus.

5. Declarations

Availability of data and materials. All data used in this article are included within them and in the Supplementary Materials (Files S1–S3).

Competing interests. The authors declare that they have no competing interests.

Authors’ contributions. Conceptualization: LO. Data curation: LO. Formal analysis: LO. Funding acquisition: MCM, PMD. Investigation: LO, MCM, PMD. Resources: MCM, PMD. Supervision: MCM, PMD. Visualization: LO. Writing – original draft: LO. Writing – review and editing: LO, MCM, PMD.

6. Acknowledgements

We are grateful to Amoret Spooner and Katherine Child (OUMN), Gunvi Lindberg (NHRS), Henrik Enghoff (ZMUC), Richard Packauskas (Fort Hays State University), Herbert Zettel (NHMW), Luis Ovidiu Popa (MGAB), and Karla Schneider (ZMHB) for kindly providing photographs of the type specimens examined in the present work. We also thank Thomas J. Henry (USNM), Harry Brailovsky (UNAM), Aline Barcellos (MCNZ), Christiano F. Schwertner (MZSP), Dimitri Forero (PUJ), Eduardo Flores (UNAL), Diego Carpintero (MACN), and Emilia Constanza Perez (IFML) for the loan of specimens. This work was partially funded by and the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) PIP 1505, and Proyecto de Incentivos UNLP 2024-2027 N1031.

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Supplementary material

Supplementary material 1

Files S1–S3

Olivera L, Melo MC, Dellapé PM (2026)

Data type: .zip

Explanation notes: File S1. Detailed occurrence records for the species of Acanthocephala examined in this study [.xlsx file]. — File S2. Data matrix for the cladistic analysis, comprising encoded continuous and discrete characters [.txt file]. — File S3. Summary of morphometric data for the characters included in the cladistic analysis of Acanthocephala species. Values are presented as Mean ± Standard Deviation (SD) for each continuous variable [.xlsx file].

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

Download file (84.91 kb)

Keywords

1. Introduction

2. Material and methods

2.1. Morphological analysis

2.1.1. Specimens studied and collections

2.1.2. Morphological examination and ­photographs

2.1.3. Selection of taxa

2.2. Phylogenetic analysis

2.2.1. Search strategies

2.2.2. List of characters

3. Results

3.1. Cladistic analysis

3.2. Taxonomy

Acanthocephala Laporte, 1833

Type species.

Diagnosis.

Redescription.

Specific taxonomic remarks.

Key to subgenera of Acanthocephala Laporte

Acanthocephala (Acanthocephala) Laporte, 1833

Type species.

Included species.

Diagnosis.

Description.

Distribution.

Specific nomenclatorial remarks.

Discussion.

Acanthocephala (Spinipedia) subgen. nov.

Type species.

Included species.

Diagnosis.

Description.

Etymology.

Distribution.

Discussion.

Acanthocephala (Contrastata) subgen. nov.

Type species.

Included species.

Diagnosis.

Description.

Etymology.

Distribution.

Discussion.

Acanthocephala (Pronoptera) subgen. nov.

Type species.

Included species.

Diagnosis.

Description.

Etymology.

Distribution.

Specific nomenclatorial remarks.

Discussion.

Acanthocephala (Metapodiessa) Kirkaldy, 1902 REVALIDATED NAME

Type species.

Included species.

Diagnosis.

Description.

Distribution.

Specific nomenclatorial remarks.

Discussion.

4. Discussion and conclusions

5. Declarations

6. Acknowledgements

7. References

Supplementary material

2.1.2. Morphological examination and photographs