Taxonomic revision and phylogeny of the sharpshooter genus Dasmeusa Melichar, 1926, with a scanning electron microscopy study of D. pauperata (Fabricius, 1803) (Hemiptera: Cicadellidae: Cicadellini)

) Taxonomic revision and phylogeny of the sharpshooter genus Dasmeusa Melichar


Introduction
Melichar produced an extensive monograph on the taxonomy of the Cicadellinae ("Monographie der Cicadellinen"), which was published, posthumously, between 1924 and 1951 (Melichar 1924(Melichar , 1925(Melichar , 1926(Melichar , 1931(Melichar , 1951. In the third volume, Melichar (1926) provided an identification key to 101 genera of the "Cicadellaria", a group roughly equivalent to the tribe Cicadellini. The genus Dasmeusa was included in this key (p. 324) but was not formally described in the Monographie, nor species were included. China (1938) designated Cicada pauperata Fabricius, 1803 as the type-species of Dasmeusa. Metcalf (1955) included a second species in the genus, Dasmeusa flavescens Metcalf, 1955, which was a new name for the preoccupied Tettigonia lurida Signoret, 1853. The genus was also catalogued or listed by Neave (1939), Evans (1947), Metcalf (1965), Zanol and de Menezes (1982), the circa 330 known genera of the Cicadellinae has so far not been attempted, the generic groups proposed by Young (1977), including the Paromenia group, are regarded as reasonable starting points for outgroup choices in cladistic studies. Cavichioli (1992), in his doctoral study, carried out a phylogenetic analysis, based on morphological data, of the Paromenia group. In his study, Dasmeusa was recovered as the sister group of Tacora, a relationship supported by the angulated inferior third of the frons. Although Young (1968Young ( , 1977Young ( , 1986 published outstanding monographs of the Cicadellinae, including a myriad of detailed descriptions of new genera and species, as well as redescriptions, we believe that further morphological investigations on this subfamily are necessary, focusing on the general body morphology, male terminalia, and especially the female terminalia (Mejdalani 1998). Various structures can be better described and used for an in depth understanding of species phylogenetic relationships and detailed taxonomic studies (Mejdalani 1995(Mejdalani , 1998Carvalho and Mejdalani 2014). Furthermore, the phylogenetic relationships within the Proconiini and Cicadellini are poorly understood, and cladistic studies involving species of one genus or groups of genera are still relatively rare. Available publications are relatively recent (e.g., Cavichioli 1997, Takiya and Mejdalani 2004, Ceotto and Mejdalani 2005, Ceotto et al. 2007, Leal et al. 2009, Felix and Mejdalani 2011, Silva et al. 2015, and Leal et al. 2020) and none of them are dedicated specifically to the genus Dasmeusa.
In the present paper, we redescribe the genus Dasmeusa and describe four new species. All previously known species are redescribed, including new diagnostic morphological characters (with the exception of D. imperialis because it was recently described). Dasmeusa flavescens Metcalf, 1955 and Erythrogonia bicolor Metcalf, 1949 are herein considered junior synonyms of the type-species Dasmeusa pauperata (Fabricius, 1803). We also provide an identification key to males, a list of the valid species, and a map showing their distribution. Morphological data are employed to investigate the phylogenetic relationships among the species of Dasmeusa; our outgroups include six genera of the Paromenia group. Scanning electron microscopy (SEM) was employed for a detailed study of the integument of the type-species, including sensilla, surface sculpturing, brochosomes, organ of Evans, and various other structures.

2.
Material and methods

Specimens examined
The studied specimens belong to the following institu-  (NHMW). In quotations of label data, a reversed virgule (\) separates lines on a label. Using the online tool SimpleMappr (Shorthouse 2010), we prepared an updated map to show the known distribution of Dasmeusa species in South America. Records were obtained from specimens deposited in the collections mentioned above, as well as from the literature (Young 1977;Zanol and de Menezes 1982;Basset 1999;Cavichioli and Chiamolera 1999;McKamey 2007;Wilson et al. 2009;Pecly et al. 2019).

Terminology and techniques for preparation of specimens
The morphological terminology adopted here followed mainly Young (1968Young ( , 1977Young ( , 1986, except for the head (Hamilton 1981;Mejdalani 1993Mejdalani , 1998 and female terminalia (Nielson 1965;Hill 1970). Use of the term paraphyses (plural; singular: paraphysis) for Dasmeusa, as well as for other sharpshooter genera, followed Young (1977: 291), who employed the plural for biramous structures like the ones treated here. Use of the term gonoplac followed Mejdalani (1998). The total length of specimens was measured from the apex of the crown to the tips of the forewings at rest position (Young 1977). Techniques for preparation of genital structures followed mainly those of Oman (1949) for males and Mejdalani (1998) for females. Dissected parts were stored in small vials with glycerin, as suggested by Young and Beirne (1958). Photographs of the body in dorsal view were taken with a Leica M205 C stereomicroscope and processed with LAS 4.6 software. Composite images created from the in-focus areas of the original photographs were produced by CombineZP, a free software developed by Alan Hadley (http://combinezp.software.informer.com). Photographs of the ovipositor valvulae were taken with a Leica DMC2900 light microscope and processed with LAS 4.6 software.

Scanning electron microscopy (SEM)
The external morphology of D. pauperata was studied using scanning electron microscopy (SEM). Our descriptions of microstructures and sensilla followed mainly Evans (1973), Dietrich (1989), Gorb (2001), and Hao et al. (2016). Specimens were glued to an iron stub with double-sided tape, coated with gold, and analyzed in a JEOL JSM 6510 scanning electron microscope at Centro de Microscopia Eletrônica, Instituto de Biologia (Universidade Federal do Rio de Janeiro).

Character coding
Morphological characters of the head, thorax, and male terminalia were identified based on their topographical identity before proposing hypotheses of primary homology, i.e., character state identity (De Pinna 1991;Brower and Schawaroch 1996;Brower and De Pinna 2012), that were coded in the unpolarized data matrix (Nixon and Carpenter 1993). The order of transformation of character states was established a posteriori by the rooting procedure (see section 2.7 below). The matrix (Appendix 1) was assembled using the software Mesquite (Maddison and Maddison 2021). Character statements were composed considering the four fundamental functional components proposed by Sereno (2007), viz., locator, variable, variable qualifier (when needed), and character states. Most characters were transformational but some were neomorphic (Sereno 2007). Missing data were coded as '-'. Characters, as well as their consistency index (ci) and retention index (ri) (except for uninformative characters), are listed in the results of the phylogenetic analysis.

Cladistic analysis
The implicit enumeration algorithm of TNT was used for estimating most parsimonious trees (Goloboff et al. 2008). The outgroup Sailerana solitaris was employed for rooting the trees. Multistate characters were treated as unordered (Fitch parsimony). We carried out an equal weights search and an implied weighting search (Goloboff 1993), the latter with k = 3. The strict consensus method was employed to summarize all resulting most parsimonious trees from the equal weights analysis. Branch support was calculated using absolute decay indices (Bremer 1994) and the non-parametric bootstrap method with 1000 pseudoreplicates (Felsenstein 1985). Autapomorphic characters were included in the data ma-trix, as suggested by Yeates (1992). Character states were optimized onto the preferred tree using Winclada, ver. 1.00.08 (Nixon 2002).
Diagnosis. Specimens preserved in collections usually pale yellow; whitish-yellow to greenish-yellow in life; forewing with preapical area with irregular orange transverse band or with second apical cell with distinct red spot. Head moderately to strongly produced anteriorly; coronal suture distinct, elongate, extending anteriorly beyond interocellar line; frons, in lateral view, with inferior third slightly angulate. Pronotum with lateral margins convergent anteriorly; posterior margin rectilinear. Forewing subhyaline; apex slightly expanded and obliquely truncate; with four apical cells, base of fourth approximately aligned with base of third; costal apical cell broadened posteriorly. Male terminalia with pygofer bearing basiventral lobe; without processes; subgenital plate triangular, not fused basally to its counterpart; style without preapical lobe; aedeagus with shaft short, usually with single process, rarely with pair of processes; paraphyses present, biramous, with or without processes on stalk. Female terminalia with sternite VII well produced posteriorly; pygofer well produced posteriorly; valvula I abruptly narrowed apically, with ventroapical margin Head: in dorsal view, moderately to strongly produced anteriorly; median length of crown varying from 5/10 to 9/10 of interocular width and from 4/10 to 6/10 of transocular width; anterior margin generally rounded; without carina at transition from crown to face; coronal suture distinct, elongate, extending anteriorly beyond interocellar line; frontogenal suture extending onto crown and usually attaining ocellus; ocelli large or of moderate size, located approximately on imaginary line between anterior eye angles, or slightly before or slightly behind this line, each ocellus approximately equidistant between median line of crown and adjacent eye angle; antennal ledge, in dorsal view, varying from not protuberant to slightly protuberant; in lateral view, with anterior margin oblique and convex. Frons, in anterior view, convex; median area mostly smooth; muscle impressions distinct; in lateral view, inferior third slightly angulate; epistomal suture incomplete medially; clypeus, in lateral view, convex, continuing inferior contour of frons. Thorax: pronotum, in dorsal view, with width slightly greater than or approximately equal to transocular width of head; lateral margins convergent anteriorly; posterior margin rectilinear; dorsolateral carina complete, rectilinear, declivent anteriorly; disk without pubescence or punctures. Mesonotum with scutellum not transversely striate and without punctures. Forewing with membrane indistinct; veins not elevated; apex slightly expanded and obliquely truncate; with four apical cells, base of fourth approximately aligned with base of third; with three closed anteapical cells, their bases located more proximally than claval apex; costal apical cell broadened posteriorly; without anteapical plexus of veins; texture subhyaline. Hind wing with vein R 2+3 incomplete. Hind leg with femoral setal formula 2:1:1; first tarsomere longer than combined length of two more distal tarsomeres, with two longitudinal parallel rows of small setae on plantar surface. Coloration: head, pronotum, mesonotum, forewings, and legs of preserved specimens usually yellow (whitish-yellow to greenish-yellow in life); preapical area of each forewing with irregular orange transverse band or with distinct red spot on second apical cell. Male terminalia: pygofer, in lateral view, moderately to strongly produced posteriorly; with basiventral lobe; without processes; anteroventral margin with distinct group of microsetae. Subgenital plate, in ventral view, not fused basally to its counterpart; not extending as far posteriorly as pygofer apex. Connective, in dorsal view, usually T-shaped, rarely V-shaped; arms broad. Style, in dorsal view, without preapical lobe. Aedeagus, in lateral view, with shaft usually short and bearing single ventral process, more rarely with pair of processes or with apical digitiform projection. Paraphyses present, symmetrical or slightly asymmetrical, with or without processes on stalk. Female terminalia: sternite VII, in ventral view, well produced posteriorly; narrowing gradually towards apex. "Internal" sternite VIII, in dorsal view, usually without sclerotized areas. Pygofer, in lateral view, well produced posteriorly; posterior margin narrowly rounded to subacute; macrosetae distributed mostly on posterior half. Valvula I, in lateral view, abruptly narrowed apically, ventroapical margin somewhat sinuous, apex acute; dorsal sculptured area extending from basal portion to apex of blade, formed mostly by scale-like processes arranged in oblique lines (strigate); ventral sculptured area restricted to apical portion of blade, formed mostly by scale-like processes; base of valvula forming lobe directed anterad; ventral interlocking device located on basal third or basal half of blade. Valvula II, in lateral view, with dorsal margin convex; blade with about 45 to 60 non-contiguous, mostly subtriangular teeth; preapical prominence distinct; apex obtuse; denticles distributed on teeth and on dorsal and ventral apical portions of blade (ventral dentate apical portion longer than dorsal portion); valvula with ducts extending towards teeth and apical area. Gonoplac of the usual Cicadellinae type: in lateral view, with basal half narrow; apical half expanded, gradually narrowing towards apex; latter obtuse.  (Fig. 1  Coloration (Fig. 1A). Head, pronotum, and mesonotum light brown; ocelli orange. Forewing pale yellow, translucid, with veins light brown, preapical area with irregular, orange transverse band. Face, lateral and ventral portions of thorax, and legs mostly light brown.
Taxonomic notes. Cavichioli and Chiamolera (1999) considered the habitus of D. basseti ( Fig. 1A) similar to that of D. pauperata (Fig. 1H), whereas they regarded the male terminalia similar to those of D. isabellina, mainly due to the shape of the aedeagus (Figs 2E, 5E). However, D. basseti can be easily distinguished from these two species by the paraphyses (Fig. 2F, G) with the rami fused to each other along their basal halves, each one bifurcate at apex. Coloration (Fig. 1B). Head, pronotum, mesonotum, and legs pale yellow. Forewing pale yellow, translucid, preapical area with irregular orange transverse band.
Female unknown.
Etymology. The name of the new species, dinizi, refers to the biologist André Luis Diniz Ferreira, in recognition of his friendship to the first author and contribution as a skilled insect collector. Taxonomic notes. Dasmeusa dinizi sp. nov. (Fig. 1B) is similar to D. oriximina sp. nov. (Fig. 1G). These species share many similarities in the male terminalia, especially in the aedeagus and paraphyses. However, D. dinizi can be recognized by the two pairs of small processes on the paraphyses stalk ( Fig. 3G), one located dorsally at the base of the apical third and another ventrally at the apex. Coloration (Fig. 1C). Head, pronotum, and mesonotum pale yellow. Forewing pale yellow, second apical cell with distinct red spot.

Dasmeusa falcifera
Male terminalia. Pygofer (Fig. 4B), in lateral view, well produced posteriorly; posterior margin narrowly rounded; macrosetae (most of them very large) distributed on posterior half but some located more anteriorly. Subgenital plate (Fig. 4C), in ventral view, with basal half broad and distal half very narrow; with elongate uniseriate macrosetae on basal half, microsetae distributed along outer lateral margin. Connective (Fig. 4D), in dorsal view, V-shaped; stalk not carinate dorsally, much longer than one arm width. Style (Fig. 4D), in dorsal view, slender, elongate, not extending posteriorly beyond apex of connective; slightly narrowed apically, apex obtuse. Aedeagus symmetrical (Fig. 4E); in lateral view, shaft elongate, ventral margin with dentiform process at basal half and elongate process at apex; gonoduct distinct, gonopore located apically. Paraphyses, in dorsal view (Fig. 4F), slightly asymmetrical; elongate, extending well beyond subgenital plate apex; stalk much shorter than rami; in lateral view (Fig. 4G), rami with apexes slightly directed upwards.  Taxonomic notes. As mentioned in the key, D. falcifera sp. nov. (Fig. 1C) shares with D. rafaeli sp. nov. (Fig. 1I) the presence of a distinct red spot at the second apical cell of the forewing. The former can be readily distinguished from the latter, as well as from the remaining known species of the genus, by paraphyses with the apical portion of the rami, in lateral view, directed dorsally (Fig. 4G) and pygofer well produced posteriorly and with the posterior margin narrowly rounded (Fig. 4B).
Coloration (Fig. 1E). Head, pronotum, and forewing mostly orange; mesonotum dull white. Frons mostly orange; clypeus pale yellow. Remainder of face (gena and lorum) and lateral and ventral portions of thorax pale yellow; legs mostly pale yellow to orange.
Female unknown. Taxonomic notes. Cavichioli and Chiamolera (1999) considered D. isabellina (Fig. 1E) similar to D. basseti (Fig. 1A) in the male terminalia, especially the aedeagus. These two species can be distinguished from each other by the shape of the apex of the paraphyses rami, which are bifurcated in D. basseti (Fig. 2F) and not bifurcated in D. isabellina (Fig. 5F). The dorsal region of the body (Fig. 1E) is somewhat more orange in D. isabellina than in other species of the genus. Coloration (Fig. 1F). Head, pronotum, and mesonotum pale yellow. Forewing translucent with transverse broad orange stripe across bases of apical cells.
Male terminalia. Pygofer (Fig. 7B), in lateral view, with posterior margin rounded; macrosetae distributed on posterior half but some located more anteriorly. Subgenital plate (Fig. 7C), in ventral view, with basal half broad and distal half very narrow; with elongate uniseriate macrosetae on basal half, microsetae distributed along outer lateral margin. Connective (Fig. 7D), in dorsal view, T-shaped; stalk much shorter than one arm width. Style (Fig. 7D), in dorsal view, slender, elongate, extending posteriorly well beyond apex of connective; slightly narrowed apically, apex obtuse. Aedeagus symmetrical (Fig.  7E); shaft short; ventral margin of shaft with preapical portion produced into robust process directed ventrally, posterior margin of process smooth; gonoduct distinct, gonopore located apically. Paraphyses symmetrical; elongate, extending well beyond subgenital plate apex; in dorsal view (Fig. 7F), stalk subequal in length to rami; rami slightly curved and crossing each other apically; in lateral view (Fig. 7G), stalk approximately rectilinear and with pair of strong dorsoapical processes, rami directed dorsally, narrowed apically.
Female unknown.  1G) is similar to D. dinizi sp. nov. (Fig. 1B) in the male terminalia, especially the aedeagus. The former species can be easily distinguished from the latter and other Dasmeusa species by the conspicuous dorsal processes of the paraphyses stalk (Fig. 7G). Coloration (Fig. 1H). Head, pronotum, and mesonotum mostly brownish-yellow. Forewing yellow, preapical area with irregular orange transverse band. Face, lateral and ventral portions of thorax, and legs pale yellow.
Male terminalia. Pygofer (Fig. 8C), in lateral view, with posterior margin broadly rounded; macrosetae distributed on posterior half but some located more anteriorly. Subgenital plate (Fig. 8D), in ventral view, with basal third broad and distal two-thirds strongly narrowed; with elongate uniseriate macrosetae on basal third, microsetae distributed mostly along outer lateral margin. Connective (Fig. 8E), in dorsal view, T-shaped; stalk not carinate dorsally, shorter than one arm width. Style (Fig. 8E), in dorsal view, somewhat S-shaped, slender, extending posteriorly beyond apex of connective; obtuse apically. Aedeagus symmetrical (Fig. 8F); shaft, in lateral view, with large ventral lobe and dorsoapical digitiform projection; without processes; gonoduct distinct, gonopore located apically. Paraphyses symmetrical; extending approximately as far posteriorly as aedeagal apex; stalk longer than rami; in dorsal view (Fig. 8G), stalk slender and rami fused at base, but strongly divergent at apical half, each ramus irregularly serrate and with small dentiform projection at basal portion (Fig. 8H); in lateral view (Fig. 8I), stalk sinuous, fused bases of rami robust and apices of rami directed dorsally. Taxonomic notes. Dasmeusa pauperata can be readily distinguished from the remaining known species of the genus by the aedeagus with a large ventral lobe and a dorsoapical digitiform projection (Fig. 8F). The shape of paraphyses, with strongly divergent arms, is also unique (Fig. 8G-I). As mentioned above, Dasmeusa flavescens Metcalf, 1955 was proposed as a new name for Tettigonia lurida Signoret, 1853, which was preoccupied by T. lurida Germar, 1821. Young's (1977) confirmation of Metcalf's (1955) generic assignment was based on a study of the female lectotype of T. lurida (Fig. 10A-F), which is deposited in the Naturhistorisches Museum Wien. Young (1977) also suggested that D. flavescens, which was originally described from Brazil (Young 1977 Metcalf, 1949, male holotype, which was treated by Young (1977)  Suriname (Wilson et al. 2009), could be a junior synonym of D. pauperata (Fabricius, 1803). We have been able to study photographs of the T. lurida lectotype (Fig. 10A-F) and a female specimen from Pará State ("Belém \ Pará -Brazil \ IX.1964 \ E. Dente" [MZSP]). In agreement with Young's (1977) suggestion, it appears to us that D. flavescens is actually a junior synonym of D. pauperata. Young (1977Young ( : 1105 treated Erythrogonia bicolor Metcalf, 1949 as incertae sedis because he did not find specimens that could be associated with this name. We have examined a photograph of the male holotype (body in dorsal view) of E. bicolor, from Guyana, which is deposited at the entomological collection of the North Carolina State University, Raleigh (Fig. 11A). The external form and coloration, as well as the illustrations of the male terminalia provided by Metcalf (1949), suggest that this species is also a junior synonym of D. pauperata.  (Figs 1I, 12A) with pronotum, in dorsal view, with width slightly greater than transocular width of head; lateral margins slightly convergent anteriorly. Forewing with base of fourth apical cell approximately aligned with base of third.
Taxonomic notes. The color pattern of D. rafaeli sp. nov. (Fig. 1I) is similar to that of D. falcifera sp. nov. (Fig. 1C) because both have a distinct small red spot at the second apical cell of the forewing. The aedeagus of D. falcifera bears a conspicuous dentiform process at the basal half of the ventral margin (Fig. 4E), a feature that is not present in D. rafaeli (Fig. 12F).

Scanning electron microscopy
The use of scanning electron microscopy (SEM) allowed us to study in detail the integument of Dasmeusa pauperata, the type-species of the genus. The following features of the integument were observed for the first time in this genus and are also poorly known in the Cicadellidae as a whole: microtrichia ( have also been able to observe brochosomes on various parts of the body, such as the compound eyes (Fig. 14C), gena (Fig. 14I), maxillary stylets (Fig. 15I), mesonotum (Fig. 16D, E), claval sulcus and other areas of the forewing (Fig. 16H, I), legs (Fig. 17D, E), sternal surface of the abdomen (Fig. 18G), and abdominal spiracles (Fig.  18L).

Phylogenetic analysis
The data matrix included 40 morphological characters, of which 14 are from the external morphology and coloration (head and thorax) and 26 from the male terminalia; these characters were coded for 15 terminal taxa (six of them outgroups) (Table S1). Thirty-one characters are binary and nine are multistate; only eight characters were non-informative for the parsimony analysis. The characters and their states are listed below (non-informative ones are indicated).  (Fabricius, 1803). A Microtrichia at apex of clypeus; B apex of clypeus and labrum; C labrum and second article of labium; D third article of labium and apex of maxillary stylets; E apex of third article of labium and maxillary stylet; F sensilla coeloconica of third article of labium; G sensillum coeloconicum at higher magnification; H maxillary stylet and lateral projections of mandibular stylet (asterisks); I apex of maxillary stylets, with brochosomes.

Main results of the phylogenetic analysis
The analysis with equal weights resulted in nine equally most parsimonious trees (L = 88, CI = 0.580, RI = 0.602). The strict consensus of these trees ( Figure S1) is almost entirely polytomous within Dasmeusa, but D. rafaeli sp. nov. + D. falcifera sp. nov. and D. imperialis + D. dinizi sp. nov. consistently formed clades. All trees recovered Dasmeusa as monophyletic, although with relatively low support scores. The implied weighting analysis (k = 3) resulted in two trees (fit = 7.85000), both with the same topology for the ingroup. This ingroup topology, which was also found in one of the nine most parsimonious trees with equal weights, is considered the preferred hypothesis (Fig. 19); it is as follows: ((D. basseti (D. mendica (D. rafaeli sp. nov., D. falcifera sp. nov.))) (D. isabellina (D. oriximina sp. nov. (D. pauperata (D. imperialis, D. dinizi sp. nov.))))). Jozima appeared as the sister group of Dasmeusa in all calculated trees. Unambiguous apomorphies were optimized onto the preferred tree (Fig. 19).

Phylogenetic analysis
The monophyly of Dasmeusa was recovered in all nine most parsimonious trees ( Figure S1) and in the implied weighting search (Fig. 19), although with relatively low support scores in both analyses. Dasmeusa was supported by the following apomorphic characters mapped onto the preferred tree (Fig. 19): (1)   27, s. 1, Fig. 2F). Preliminary data suggest that the phylogeny of the Cicadellini is characterized by a great number of homoplastic events. Therefore, the apomorphic conditions proposed here should be evaluated primarily in the context of the Paromenia group. However, these characters are of course available for further evaluation in future, more comprehensive phylogenetic analyses of the tribe. The hypothesis of the sister group relationship between Dasmeusa and Jozima is based on two apomorphic features in the context of the Paromenia group: (1) short and compact aedeagal shaft (c. 35, s. 1, Fig. 3E) and (2) presence of ventroapical process of aedeagus (c. 36, s. 1, Fig. 3E). Therefore, our results do not support Young's (1977) suggestion that Dasmeusa and Paromenia are very closely related genera. Likewise, they do not support Cavichioli's (1992) cladistic hypothesis (unpublished doctoral study), in which Tacora was recovered as the sister group of Dasmeusa. Young (1977) observed that specimens of Dasmeusa are more delicate (i.e., slenderer) than those of Jozima and have paraphyses in the male terminalia (Fig. 2F). Tacora can be readily differentiated from Dasmeusa by the presence of processes on the male pygofer, absence of paraphyses, and conspicuous color pattern (Young 1977;Takiya and Mejdalani 2002;Mejdalani et al. 2011;Wilson et al. 2009).
The external morphology is apparently quite conservative within the genus Dasmeusa, with the exception of male terminalia characters (see taxonomic discussion below). Therefore, only a limited number of characters (40) could be considered in the present study for the phylogenetic analysis. However, we hope that our preliminary hypothesis of relationships within Dasmeusa (Fig. 19) can be tested in the future by means of the consideration of molecular data. Young (1977: 10) stated that the "Cicadellini are an intricate group" and their "morphology suggests rapid radiation and often shows small discontinuities." Perhaps, Dasmeusa species exemplify this rapid radiation situation, a possibility that could be tested in the context of a molecular phylogenetic analysis.

Scanning electron microscopy of Dasmeusa pauperata
Microtrichia (subcellular projections) were found in various parts of the body of D. pauperata, such as the antennal pedicel (Fig. 14E), apex of the clypeus (Fig. 15A), mesonotum (Fig. 16B, C), base and apex of the forewing (Fig. 16F, G, K, L), abdominal sternites and laterotergites (Fig. 18A, B, E, F, G, I, L), tarsi and pretarsi (Fig. 17I, J, K, L). These structures give the integument a grainy to finely pubescent appearance at low magnification (Dietrich 1989). According to Hao et al. (2016), they are small rigid projections that occur alone or in groups of two or three. Their function is possibly to assist in increasing frictional force in contact regions (Gorb 1996(Gorb , 1997(Gorb , 2001. Gonzaga-Segura et al. (2013) studied the sensory organs in the antennal flagellum of Leptoglossus zonatus (Dallas, 1852) (Heteroptera: Coreidae). Micro-trichia were found on the second flagellomere and, according to those authors, their shape and location suggest that they act as mechanoreceptors, informing the insect about movements of the antenna. They also reported that in this coreid species sensilla coeloconica are generally accompanied by s. basiconica and immersed between microtrichia. We have observed a similar situation in the abdominal sternum of D. pauperata, with microtrichia located close to s. coeloconica (Fig. 18G, I).
We observed brochosomes distributed close to microtrichia in various body regions (Fig. 18G, L). Brochosomes are submicron proteinaceous secretory particles synthetized by specialized regions of the Malpighian tubules of leafhoppers (Day and Briggs 1958;Hix 2001;Rakitov 2002;Rakitov and Gorb 2013). These insects display specialized behaviors for applying brochosomes, using the complex setal armature of legs, onto the integument and, more rarely, onto egg nests (Rakitov 1997(Rakitov , 2002Hix 2001;Azevedo-Filho and Carvalho 2005). These particles are believed to be strongly hydrophobic, having the function of protecting the integument against the adhesion of water and honeydew (Rakitov 1997(Rakitov , 2009Rakitov and Gorb 2013).
The organ of Evans, sometimes referred to as the maxillary sensillum, is a peculiar structure located, in leafhoppers, on the maxillary plate, next to the lorum (Fig.  14K, L). However, according to Bourgoin (1986), the position of this organ is variable within the Auchenorrhyncha (for instance, it can occur above the maxillary plate, i.e., at the gena, in some fulgoroids, sometimes close to the antennal foramen). It occurs between the eye and the antennal foramen in the Coleorrhyncha and is apparently absent in the Heteroptera and Sternorrhyncha (Bourgoin 1986). This organ has been described in leafhoppers as a finger-shaped lobe located within a pit, and has been interpreted as a maxillary gland, modified and reduced maxillary palp, or as a kind of sensory organ (Evans 1973;Cwikla and Freytag 1983;Bourgoin 1986;Zanol 1988;Tavella and Arzone 1993;Mejdalani 1993Mejdalani , 1998Dmitriev 2010). Superficially, the organ of Evans is somewhat similar to sensilla coeloconica, as, e.g., the ones described by Ahmad et al. (2016) from the antenna of the pentatomid Perillus bioculatus (Fabricius, 1775). This organ is well developed and occurs in the usual position, i.e., at the maxillary plate close to the lorum, in D. pauperata (Fig. 14K, L).
Insect sensilla are ectodermal organelles built up by a definite number of characteristic cells (Altner and Prillinger 1980). They consist of an exocuticular outer structure by or through which stimuli are conveyed to one or more sensory cells within the sensilla (Brożek and Bourgoin 2013). Insects use their sensilla extensively during every step of host probing, acceptance, and feeding (Foster et al. 1983;Parveen et al. 2015). Accordingly, the mouthparts of the Auchenorrhyncha bear many kinds of sensilla. In the labium of D. pauperata we have identified sensilla basiconica (Fig. 15E, H) and s. coeloconica (Fig. 15F, G), as well as the very common s. trichodea (Fig. 15D, E, F). Considering that there are no chemoreceptors on the stylets, which are the structures that enter the tissues of the host plant, these labial sensilla probably provide the only direct sensorial link of the mouthparts with the host plant (see Cobben 1988 andBourgoin 2013).
According to Brożek and Bourgoin (2013), sensilla basiconica have a gustatory function, being thus chemoreceptors. They can also receive tactile stimuli originated from the host plant, acting as mechanoreceptors (Wang et al. 2015;Zhao et al. 2010), or function as hygroreceptors (Usha Rani and Madhavendra 1995). A small number of these sensilla are typically located on the apical area of the labium of D. pauperata (Fig. 15E), and a similar situation was observed by Leopold et al. (2003) in the glassy-winged sharpshooter [Homalodisca vitripennis (Germar, 1821)] and by Quintas and Mejdalani (2021) in the fourth stadium nymph of the sharpshooter Cavichiana bromelicola Mejdalani et al., 2014. Leopold et al. (2003 speculated that the small number of sensilla at the labial paired apical sensory fields of H. vitripennis might be related to the wide host range of this xylem-feeder (Blua et al. 2000;Hoddle et al. 2003), which includes at least 100 documented plant species; therefore, extensive specific cues from a given plant would not be required. Sensilla coeloconica are widely distributed on the dorsal surface of the three labial segments of the cicadid Meimuna mongolica (Distant, 1881) (Hao et al. 2016). Altner and Prillinger (1980) suggested that these sensilla have distinct functions, including hygro-, thermo-, and chemoreceptors. They can perhaps feel by contact or gustation and also respond to odors (Zacharuk 1980;Ahmad et al. 2013). In addition to the labium (Fig. 15F, G), we have found a conspicuous kind of s. coeloconicum in the abdominal sternum of D. pauperata (Fig. 18E, F, G, H). A similar sensillum was observed by Dietrich (1989) in the abdomen of the Proconiini sharpshooter Oncometopia orbona (Fabricius, 1798).
Sensilla placodea were found on the frons of D. pauperata (Fig. 14J). According to Dietrich (1989), these structures consist of a sensory plate of the cuticle surrounded by a membranous ring. Brożek and Bourgoin (2013) suggested that in the labium of Fulgoroidea (e.g., Achilidae and Nogodinidae) they are chemoreceptors, with an olfactory function, or perhaps thermoreceptors. Kanturski et al. (2017) suggested that these sensilla act as chemoreceptors and hygroreceptors in aphid antennae, whereas Gonzaga-Segura et al. (2013) mentioned that they are located at the base of the scape and could be mechanoreceptors in coreids.
Sensilla trichodea (hair-like structures or setae) of distinct sizes, generally with a pointed apex (Fig. 18J) or sometimes with an apical pore (Fig. 18D), were observed in various portions of the body of D. pauperata; those with an apical pore (uniporous) are possibly contact chemoreceptors (see Ahmad et al. 2016). Sensilla trichodea are attached to the body surface in a cup-shaped socket (Fig. 18D) by an articulating membrane (Foster et al. 1983). These sensilla are quite abundant on the labium (Fig. 15B, C hairs, without pores, located on the lateral portions of the labium (Fig. 15C, D, E), probably detect the degree of labial bending during probing (Backus 1988;Parveen et al. 2015). Parveen et al. (2015) investigated the diversity of labial sensilla in phytophagous (Pentatominae) and predatory (Asopinae) pentatomid bugs; they found that sensilla trichodea are more concentrated at the apical portion of the labium, where they come into contact with the substrate during feeding, probably exerting a gustatory function and receiving stimuli from the plant or animal host. We have observed s. trichodea positioned between the eye ommatidia (Fig. 14B). Such interommatidial sensilla were also found by Quintas and Mejdalani (2021) in C. bromelicola.

Taxonomy and known distribution of Dasmeusa
With the addition of four new species and the treatment of D. flavescens as a junior synonym of D. pauperata, the genus Dasmeusa currently includes nine species. Our comparative morphological studies indicate that the following combination of easily observable features will most readily distinguish Dasmeusa (Figs 1A-I, 13A-D) from other Neotropical Cicadellini genera: (1) head well to strongly produced anteriorly, with coronal suture distinct, elongate, and extending anteriorly beyond interocellar line ( Fig. 2A); (2) inferior third of frons slightly angulate (Fig. 10B); (3) pronotum with lateral margins convergent anteriorly and posterior margin rectilinear ( Fig. 2A); (4) forewing subhyaline, its apex slightly expanded and obliquely truncate, base of fourth apical cell approximately aligned with base of third, and costal apical cell broadened posteriorly (Fig. 8B); (5) aedeagus usually with ventrally directed process (Fig. 3E); (6) paraphyses always present, with one pair of rami, with or without processes on stalk (Fig. 3F). The identification of Dasmeusa species remains somewhat difficult because they are very similar to one another externally ( Fig. 1A-I) and can only be confidently done when males are available.
Among the studied structures of the male terminalia, the paraphyses and aedeagus are the ones that provide the most useful features for the recognition of the species of the genus (see taxonomic notes for each recognized species and key to males above). Although females of Dasmeusa are still poorly known, it appears that their terminalia structures are quite conservative, showing little significant interspecific variation. For the most part, we have found so far in these structures only subtle variations in the posterior margin of the sternite VII (Figs 2H, 4H, 9A). Young (1977) indicated that male and female genital structures of Dasmeusa were similar to those of Paromenia. However, our comparisons with genera of the Paromenia group revealed similarities of the ovipositor valvula II shared not only with Paromenia but also with Onega Distant, 1908, Tacora Melichar, 1926, Alocha Melichar, 1926, Albiniana Cavichioli, 1996, and Baleja Melichar, 1926(Cavichioli 1992Cavichioli and Wyler 1992;Takiya and Mejdalani 2002;Takiya and Cavichioli 2004;Mejdalani and Rodrigues 2008;Mejdalani et al. 2011). The more conservative nature of the female terminalia of the Cicadellinae, in comparison with the male terminalia, has been mentioned, e.g., by Carvalho and Mejdalani (2014). However, the latter authors, as well as several other recent studies, have described useful features of the female terminalia for the recognition of genera and species (e.g., Takiya and Mejdalani 2004, Leal et al. 2009, Dellapé 2015, 2016, Felix and Mejdalani 2017, and Silva et al. 2017, 2018. Furthermore, in a phylogenetic analysis of a group of Proconiini genera, Ceotto and Mejdalani (2005) suggested that characters of the female terminalia were useful for supporting more basal nodes of the tree.
The known distribution of Dasmeusa is shown in Fig.  20. Records are based mainly on Pecly et al. (2019) and on specimens deposited in scientific collections. These records indicate that the genus is possibly widely distributed in the Amazon Forest, also occurring in the Atlantic Forest (Northeastern Brazil). We have also studied five females (MZSP) labeled from São Paulo State (Southeastern Brazil, Atlantic Forest); however, it appears to us that these females were possibly incorrectly labeled, as no other specimens from this part of the country have ever been collected or observed during field trips. Unfortunately, the available distribution data of Dasmeusa are still considered very fragmentary (Fig. 20). Thus, it will not be possible for us to carry out a formal biogeographic analysis of the genus at this time.