Integrative systematics of the tarantulas Euathlus Ausserer, 1875 from Argentina: cladistics, molecular phylogeny and new species (Araneae: Theraphosidae)

Maite Allegue; Nicolás Peralta-Seen; Nelson Ferretti

doi:10.3897/asp.83.e171040

Abstract

The present study contributes to the understanding of the diversity within the tarantula genus Euathlus Ausserer, 1875. Through a combination of cladistic, molecular, and morphological analyses, three new species are described: Euathlus basalticus sp. nov. from Neuquén, Euathlus kupal sp. nov. from Mendoza, and Euathlus susanae sp. nov. from the La Pampa-Mendoza provinces. Additionally, the female of Euathlus tenebrarum Ferretti, 2015 is described for the first time, revealing that the previously attributed female of this species belongs to E. basalticus sp. nov. Phylogenetic trees from both morphological and molecular datasets are presented. Preliminary molecular analyses reveal the identity and support the proposal of the species treated here. Morphological analyses found considerable diversity within Euathlus, particularly in genitalic structures, challenging the general assumption of morphological homogeneity among mygalomorph spiders. Cladistic analyses recovered the genus Phrixotrichus within Euathlus, though this hypothesis could not be tested with molecular data due to the lack of available sequences for Phrixotrichus. These results suggest that future taxonomic revisions may be complemented once molecular data become available. Altogether, our results provide new insights into the systematics and diversity of Euathlus and highlight the importance of integrative approaches for unraveling evolutionary relationships within this group.

Keywords

Andes, morphology, Mygalomorphae, South America, taxonomy

1. Introduction

The genus Euathlus Ausserer, 1875 comprises a monophyletic group of medium-sized tarantulas (Perafán and Pérez-Miles 2014; Ferretti 2015; Allegue and Ferretti 2025) distributed in South America (Argentina, Chile and Peru). Its distribution extends almost exclusively along the Andean highlands and lowlands, although some species are present in flat regions of the Argentinean Patagonia (Allegue and Ferretti 2025). These tarantulas show a high diversity in Chile and also one species has been recorded for Peru. During recent years, in Argentina, the number of species described has been increasing (Allegue and Ferretti 2025). However, there is still a huge gap regarding the knowledge of the systematics, evolution and diversification of the species of this genus in South America. For example, some preliminary molecular evidence was reported for the genus by Allegue and Ferretti (2025), who included mitochondrial data for five Euathlus species. However, because most taxa were not represented in that phylogeny, the molecular framework for the genus remains incomplete.

Tarantulas and most mygalomorph spiders usually represent a challenge to taxonomists due to their extreme morphological homogeneity (Wilson et al. 2023). Fortunately, the robustness of tarantula systematics has also increased considerably in recent years due to numerous studies incorporating molecular data. DNA-based methods are usually used in systematics as a tool for species delimitation, discovery, and identification. By analyzing discrete mitochondrial genetic regions, it is often possible to achieve reliable species-level identifications and detect cryptic diversity in animals (Ferretti et al. 2024; Hebert et al. 2003; Montes de Oca et al. 2015; Vasconcelos et al. 2016; Zhou et al. 2019). The use of a universal DNA ‘barcode’ fragment of the cytochrome c oxidase I (COI) gene has been established as a useful tool for generating the initial species hypotheses (Korba et al. 2022). Mitochondrial genes have been preferred for studies at species-level systematics because: i) they are strongly conserved across animal groups; and ii) they are highly variable within natural populations because of their relatively elevated mutation rates. Additionally, they are easy to amplify at a relatively low cost (Galtier et al. 2009). Despite some limitations, COI sequences have proven to be useful to provide a framework for the taxonomy of some poorly studied groups, such as tarantulas (Candia-Ramírez and Francke 2021) and specifically, in this case, the genus Euathlus (Allegue and Ferretti 2025).

Beyond molecular information, morphology-based cladistics is essential in generating phylogenetic hypotheses, not only when we do not have access to fresh material or tissues from all species but also to achieve an integrative approach of total evidence. Identifying and testing patterns of shared derived characters allow the reconstruction of evolutionary relationships independently from molecular data. This independence makes them particularly valuable for assessing the congruence between morphological and molecular hypotheses, strengthening the evidence for species boundaries and lineage diversification. In taxa such as tarantulas, where morphological differentiation can be subtle or convergent, cladistic analyses based on morphology remain essential for revealing underlying phylogenetic structure and guiding an integrative taxonomy approach (Bertani 2001; Fukushima and Bertani 2017; Rios-Tamayo 2024)

Consequently, from the integration of many lines of evidence (molecular, morphology and behavior), we describe, diagnose and illustrate three new species of the genus Euathlus from central-south Argentina. In addition, the female paratype previously assigned to E. tenebrarum is herein reassigned to E. basalticus sp. nov., based on morphological and geographic information. Thus, we formally describe for the first time a conspecific female of E. tenebrarum from Junín de los Andes, Neuquén, Argentina. Moreover, we provide an updated molecular phylogeny for some representatives of the genus and performed a cladistic analysis based on morphology including the new species. Finally, we describe for the first time the sexual behavior of E. susanae sp. nov.

2. Materials and Methods

2.1. Morphological work

Specimens. Specimens of Euathlus basalticus sp. nov. were obtained both from field surveys and from preserved material. Euathlus susanae sp. nov. was collected during fieldworks. Male and female of Euathlus kupal sp. nov. and females of E. tenebrarum are described from preserved specimens. The material examined is deposited in the collection of the Museo de Ciencias Naturales “Bernardino Rivadavia” (MACN-Ar), Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina; Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS-CONICET, UNS), Universidad Nacional del Sur, Bahía Blanca, Buenos Aires, Argentina, and the Entomological Collection of the IPEEC-CONICET (CNP-CE), Puerto Madryn, Chubut, Argentina.

Methods. Specimens were examined using a Leica S APO stereoscopic microscope equipped with a MShot digital camera, and a Leica S9 with MC170 integrated camera. The structures were photographed in different focal plains and then stacked using Helicon Focus v.7. The spermathecae were dissected and then cleaned with ©Naclens enzymatic pills in distilled water. All measurements are given in millimeters and were made with digital dial calipers with an error of 0.01 mm. Appendage measurements were obtained from left appendages in dorsal view. Total lengths do not include chelicerae or spinnerets.

Terminologies. Spine notation follows Petrunkevitch (1925). Male palpal organ keel terminology follows Bertani (2000). Urticating setae terminology follows Cooke et al. (1972) and Bertani (2002). The spermathecae terminology follows Perafán and Pérez-Miles (2014), Ferretti (2015) and Ríos-Tamayo (2020).

Abbreviations. A = apical keel, ALE = anterior lateral eyes, AME = anterior median eyes, D = dorsal, OQ = ocular quadrangle, P = prolateral, PB = prolateral branch of tibial apophysis, PI = prolateral inferior keel, PLE = posterior lateral eyes, PLS = posterior lateral spinnerets, PME = posterior median eyes, PMS = posterior median spinnerets, PS = prolateral superior keel, R = retrolateral, RB = retrolateral branch of tibial apophysis, V = ventral.

2.2. Molecular work

Specimens. DNA sequences were obtained from the following specimens (GenBank accession numbers in parentheses for sequences downloaded from there): Bistriopelma matuskai — Perú, Abancay, Nevado de Ampay (OR178612); Bistriopelma sp. — Perú, Cusco, La Raya; Euathlus ameghinoi — Argentina, Chubut, Villa Dique Florentino Ameghino; Euathlus basalticus sp. nov. — Argentina, Neuquén, Ñorquín Department, Caviahue; Argentina, Neuquén, Ñorquín Department, Caviahue near Salto del Agrio waterfall; Euathlus sagei — Argentina, Neuquén, Zapala; Euathlus susanae sp. nov. — Argentina, Mendoza, Agua Escondida; Argentina, La Pampa, Cerro Negro; Euathlus ventus — Argentina, Chubut, Sarmiento; Eupalaestrus sp. — Argentina, Santiago del Estero, Parque Nacional Copo; Hapalotremus sp. — Perú, Cusco, Ollantaytambo (OR178636); Grammostola inermis — Argentina, Catamarca, Belén; Grammostola vachoni — Argentina, Buenos Aires, Tandil.

Methods. Specimens used for molecular analysis were sacrificed by putting them in the freezer, assuring a relatively quick death without causing them excessive suffering and tissue degradation. Extractions and isolation of DNA were made at the Genomic Services Laboratory (GENeTyC) from CERZOS-UNS. Muscle tissue was extracted from legs III and IV and stored in absolute ethanol at –80°C. The DNA was quantified or visualized through agarose gel electrophoresis. DNA amplification was performed for a 710-bp region of the mitochondrial gene cytochrome c oxidase subunit I (COI). We use a single set of primers to amplify the barcode region of mitochondrial COI gene: LCO-1490 (5′-GGTCAACAAATCATAAAGATATTGG-3′) and HCO-2198 (5′-TAAACTTCAGGGTGACCAAAAAATCA-3′) (Folmer et al. 1994). Polymerase chain reaction (PCR) amplification was performed under the following conditions for COI: 94°C for 9 min, then 34 cycles of 94°C for 45 s; annealing 48°C for 45 s; 72°C for 60 s; with a final elongation step of 72°C for 6 min. PCR products were purified following manufacturer’s protocol and sequenced in Macrogen (Korea). Chromatograms were edited, and sequences managed with the help of the software Geneious R11 (https://www.geneious.com).

2.3. Phylogenetic analyses

2.3.1. Maximum parsimony

A cladistic analysis based on morphology included the newly described species (Euathlus basalticus sp. nov., Euathlus kupal sp. nov., and Euathlus susanae sp. nov.), scored for 41 characters obtained by Perafán and Pérez-Miles (2014) and Ferretti (2015), with the addition of four new characters: (7) presence of teeth on the embolus keel PI, (8) number of teeth on the embolus keel PI, (40) retrolateral teeth on female chelicerae, and (41) retrolateral teeth on male chelicerae. The ingroup comprised sixteen taxa: Euathlus ameghinoi Allegue and Ferretti, 2025, E. antai Perafán and Pérez-Miles, 2014, E. atacama Perafán and Pérez-Miles, 2014, E. basalticus sp. nov., E. condorito Perafán and Pérez-Miles, 2014, E. diamante Ferretti, 2015, E. grismadoi Ríos-Tamayo, 2020, E. kupal sp. nov., E. manicatus Simon, 1892, E. mauryi Ríos-Tamayo, 2020, E. pampa Ríos-Tamayo, 2020, E. parvulus (Pocock, 1903), E. sagei Ferretti, 2015, E. susanae sp. nov., E. tenebrarum Ferretti, 2015, E. truculentus L. Koch, 1875, E. vanessae Quispe-Colca and Ferretti, 2021, E. ventus Allegue and Ferretti, 2025, and E. walteri Taucare-Ríos, Plaza and Pérez-Miles, 2025. The outgroup included Homoeomma uruguayense (Mello-Leitão, 1946), Grammostola vachoni (Schiapelli and Gerschman, 1961), Phrixotrichus jara Perafán and Pérez-Miles, 2014, Phrixotrichus scrofa (Molina, 1782), Phrixotrichus vulpinus (Karsch, 1880), and Plesiopelma longisternale (Schiapelli and Gerschman 1942). The tree was rooted using H. uruguayense. The data matrix was constructed using Mesquite v3.7 (Maddison and Maddison 2021). The cladistic analysis was carried out with TNT v1.5 (Goloboff and Catalano 2016) and to decide upon appropriate k-values, we followed the proposal by Mirande (2009) which uses a heuristic search. This method divides the values of fit/distortion into regular intervals, obtained under different k-values. This was accomplished by employing the “aaa.run” script (Mirande 2009) implemented in TNT under the commands 3 10 70 95 7. A consensus tree was also calculated with Majority rule (Cut-off = 50). Character optimization were performed with the computer software WINCLADA-ASADO 1.61 (Nixon 2004). The editing of the trees was carried out with Corel Photo Paint X7 v17.0.0.491.

Morphological data set. Multistate characters were coded as non-additive. The data matrix comprised 25 species scored for 41 characters (Table S1). Characters:

(1) Embolus direction: directed ventrolaterally = 0; directed retrolaterally = 1. (2) Relative width of bulb sclerites II + III: wide = 0; narrow (less than 10% of length) = 1. (3) Position of distal prolateral inferior keel (PI): prolateral = 0; prolateroventral = 1. (4) Apical keel: absent = 0; present = 1. (5) Ventral crest on PI: absent = 0; present = 1. (6) Subapical tooth on PI: absent = 0; present = 1. (7) Teeth on embolus keel PI: absent = 0; present =1. (8) Number of teeth on embolus keel PI: low (≤ 2) = 0; median (3–5) = 1; high (≥ 6) = 2. (9) Tegular apophysis on bulb: absent = 0; present = 1. (10) Position of male tibial apophysis: ventral = 0; prolateroventral = 1. (11) Male tibial apophysis: branches with fused bases = 0, branches with non-fused bases = 1. (12) Male tibial apophysis: with one retrolateral spine = 0; with two retrolateral spines = 1; without retrolateral spines = 2. (13) PB: with basal spine = 0; without basal spine = 1. (14) Spines of RB: without spines = 0; with 1 spine = 1; with more than one spine. (15) Position of distal spine on RB: subapical = 0; apical = 1. (16) Ventral spine on RB: absent = 0; present = 1. (17) Flexion of male metatarsus I: between the branches of tibial apophysis = 0; on the apex to the RB = 1; retrolateral to the tibial apophysis = 2. (18) Male metatarsus I: strongly curved = 0; straight = 1. (19) Spermathecal morphology: spheroid shape = 0; not spheroid shape = 1. (20) Spermathecae with a lateral spheroid chamber: absent = 0; present = 1. (21) Spermathecal receptacles: single = 0; bifurcated = 1. (22) Spermathecal neck: straight = 0; spiralled = 1. (23) Digitiform projections on spermathecae: absent = 0; present = 1. (24) Female palpal tibia spination: with apical spines only = 0; with apical and others ventral spines = 1; with apical and prolateral spines = 2. (25) Labial cuspules: numerous (> 20) = 2; moderate amount (10–20) = 1; few (< 10) = 0. (26) Sternum: as long as wide = 0; longer than wide = 1. (27) Extension of scopula on metatarsus I: complete = 0; more than a half (distal 2/3) = 1; distal half = 2. (28) Extension of scopula on metatarsus II: more than half (distal 2/3) = 0; distal half = 1. (29) Extension of scopula on metatarsus III: distal half = 0; less than half (1/3) = 1; only apical (1/4, 1/5) = 2. (30) Extension of scopula on metatarsus IV: less than half (1/3) = 0; only apical (1/4, 1/5) = 1; absent scopula = 2. (31) Scopulae on tarsi I: entire = 0; widely divided = 1. (32) Scopulae on tarsi II: entire = 0; narrowly divided = 1; widely divided = 2. (33) Scopulae on tarsi III: entire = 0; narrowly divided = 1; widely divided = 2. (34) Scopulae on tarsi IV: entire = 0; narrowly divided = 1; widely divided = 2. (35) Tarsal claws: with teeth = 0; without teeth = 1. (36) Length of urticating setae type III: short (< 0.75 of optical field diameter of microscope; 40×) = 0; medium sized (0.75–1.5 of optical field diameter; 40×) = 1; long (> 1.5 of optical field diameter; 40×) = 2. (37) Tibial apophysis: with two branches = 0; with one branch = 1. (38) Tibial apophysis with two branches: both with equal development = 0; both with subequal development = 1; RB more developed than PB = 2. (39) Number of patches of urticating setae: one central dorsal = 0; two lateral patches = 1. (40) Retrolateral teeth on female chelicerae: absent = 0; present = 1. (41) Retrolateral teeth on male chelicerae: absent = 0; present = 1.

2.3.2. Maximum Likelihood

Sequence alignment of the COI fragment was conducted with the MAFFT v7.017 (Katoh et al. 2002) plug-in implemented in Geneious R11 using default parameters. Maximum Likelihood phylogenetic inference was estimated with the software IQ-TREE v1.6.8 (Nguyen et al. 2015). We used IQ-TREE to first select the best-fit partitioning scheme and corresponding evolutionary models of the matrix through ModelFinder (Kalyaanamoorthy et al. 2017), and then to infer the best tree and estimate clade support by means of 1000 replicates of ultrafast bootstrapping (Hoang et al. 2018). The tree was rooted with Hapalotremus sp. and edited using FigTree v1.4.3 (Rambaut 2009) (http://tree.bio.ed.ac.uk/software/figtree) and Corel Photo Paint X7 v17.0.0.491.

2.4. Map construction

The map (Fig. 18) was made using the software QGIS (https://qgis.org). The distribution points of Euathlus species were obtained from geographic coordinates from published taxonomic works available in the World Spider Catalog (2025) (https://wsc.nmbe.ch). The records of the species described in this study were georeferenced directly at the field or the data from museum labels.

2.5. Sexual behavior

For the description of the sexual behavior of Euathlus susanae sp. nov. we performed two male-female pairings. We obtained one mating. Durations of behaviors are expressed in seconds. The courtship event was estimated before the male-female contact, from the first behavioral unit observed, in our case leg tapping with leg I. Copulation started when the male performs the first palpal insertion.

3. Results

3.1. Maximum parsimony

The implied weighting (IW) search yielded 33 equally parsimonious trees, with k-values of 1.87–9.49 and tree lengths of 100–102 steps. For k = 15.20, four equally parsimonious trees were recovered, each 99 steps long. The trees depicted in Figure 1 represent the four most stable topologies obtained under k = 15.20 (CI = 0.55, RI = 0.65). In all topologies, as well as in the consensus tree (Fig. 2), the genus Euathlus was recovered as paraphyletic due to the inclusion of representatives of the genus Phrixotrichus. Several clades represented in the different topologies are supported by a single homoplasy.

Figure 1.

The four most parsimonious topologies obtained from the maximum parsimony cladistic analysis of morphological data with k = 15.20 (CI = 0.55, RI = 0.65).

Figure 2.

Consensus tree obtained from Euathlus maximum parsimony cladistic analysis.

3.2. Maximum likelihood

The gene region was split by codon position and independent TIM3+F+I+G4 substitution models were applied in the analyses, as suggested by ModelFinder, built into IQTree. The log likelihood of the tree is -2839.1573 (s.e. 110.4370). The tree successfully recovered Euathlus as a monophyletic group and representatives of the tribe Grammostolini were not recovered as a clade because of the inclusion of the genus Eupalaestrus of the tribe Theraphosini (Fig. 3). Results from the molecular phylogeny showed that one individual of E. basalticus sp. nov. was recovered as a sister to E. sagei and another one was recovered as sister to this clade (Fig. 3) with high support (UFboot = 94%). All specimens of E. susanae sp. nov. were recovered as a clade sister to E. sagei + E. basalticus sp. nov. but with lower support. Finally, sister to this clade we found a monophyletic group E. ventus + E. ameghinoi (Fig. 3) with high support.

Figure 3.

Maximum likelihood tree for the cytochrome c oxidase 1 (COI) fragment, numbers at nodes represent Ultrafast bootstrap support.

3.3. Taxonomy

Family Theraphosidae Thorell 1870

Subfamily Theraphosinae Thorell, 1870

3.3.1. Genus Euathlus Ausserer, 1875

Amended diagnosis.

Modified from Allegue and Ferretti 2025). Differs from all Theraphosinae genera by the presence of type IV urticating setae in combination with males having a palpal organ morphology with two prolateral keels (PI and PS) and the tip directed retrolaterally. Most species have an apical keel. The tibial apophyses of leg I vary by one branch or two branches, both branches equal size, subequal or different sizes. All representatives of the genus have two long and thin spines retrolaterally to the tibial apophyses. Females differ by the presence of two spermathecal receptacles with a lateral spheroid chamber and only one patch of urticating setae.

Species included.

Euathlus affinis (Nicolet, 1849), Euathlus ameghinoi, Euathlus antai, Euathlus atacama, Euathlus condorito, Euathlus diamante, Euathlus grismadoi, Euathlus manicatus, Euathlus mauryi, Euathlus pampa, Euathlus parvulus, Euathlus sagei, Euathlus tenebrarum, Euathlus truculentus, Euathlus vanessae, Euathlus ventus, Euathlus walteri, Euathlus basalticus sp. nov., Euathlus kupal sp. nov., Euathlus susanae sp. nov.

3.3.2. Euathlus basalticus sp. nov. Allegue and Ferretti

https://zoobank.org/473945C3-BA42-4211-8B5F-7B6EA1-A0B499

Figures 4, 5, 6, 7, 18, Tables 1, 2

Type material.

Holotype: ARGENTINA • 1 ♂; Neuquén, Ñorquín Department, Caviahue; 37.9297°S 71.0449°W; 13 Nov. 2023; Allegue, Bambozzi, Nicoletta, Panchuk and Schwerdt leg.; UNS M1122. Paratype: ARGENTINA • 1 ♀; Neuquén, Ñorquín Department, Caviahue, near Salto del Agrio waterfall; 37.8193° S, 70.8992° W; 12 Nov. 2023; Allegue, Bambozzi, Nicoletta, Panchuk and Schwerdt leg.; UNS M1492.

Other material.

ARGENTINA • 1 ♀; Neuquén, Ñorquín Department, Copahue; 37.7964°S 71.1167°W; 25 Mar. 2009; R. Sage leg.; MACN-Ar 32688. • 1 ♀; Neuquén, Caviahue; Feb. 1968; E. Maury leg.; MACN-Ar 38155. • 1 ♀; Neuquén, Ñorquín Department, near Copahue; 37.8189°S 71.0987°W; 3 Feb. 2001; G. Cheli leg.; CNP-CE 1508. • 1 ♂; Neuquén, Ñorquín Department, near Caviahue; 37.8500°S 71.0116°W; 1658 m a.s.l.; 6 Jan. 2017; D. Ferraro leg.; MACN-Ar 37941.

Diagnosis.

Euathlus basalticus sp. nov. can be distinguished from all known congeners by a unique combination of characters in males: a dark tibial apophysis with two robust branches, the PB shorter than the RB and bearing a strong internal basal spine, while the RB has a prominent internal subapical spine (Fig. 4C–E), palpal organ piriform (Fig. 5) embolus arises gradually from the tegulum, without a distinct junction, presence of 1–2 small teeth at the tip of the prolateral inferior keel. Females can be distinguished from congeners (except from E. condorito) by having two wide seminal receptacles, rounded at the upper margin. Each receptacle bears a large semi-spheroid lateral chamber connected by a constricted duct and projecting from the lower outer margin. In addition, females differ from those of E. condorito in the orientation of the lateral chamber, which has its longest axis parallel to the lateral margin of the seminal receptacle (Fig. 6D–F).

Figure 4.

Euathlus basalticus sp. nov. male holotype (UNS M1122). A Carapace in dorsal view; B Sternum in ventral view; C Tibial apophysis in prolateral view; D Tibial apophysis in ventral view; E Tibial apophysis in retrolateral view. — Abbreviations: PB, prolateral branch; RB, retrolateral branch. — Scale bars: 1 mm.

Figure 5.

Palpal organ of Euathlus basalticus sp. nov. male holotype (UNS M1122). A. Retrolateral view; B. Ventral view; C. Prolateral view; D. Dorsal view. — Abbreviations: A, apical keel; PI, prolateral inferior keel; PS, prolateral superior keel. Red arrow indicates the distal teeth on PI. — Scale bars: 1 mm.

Figure 6.

Euathlus basalticus sp. nov. female paratype (UNS M1492). A Carapace in dorsal view; B Sternum in ventral view; C Abdomen in dorsal view; D Spermatheca; E Spermatheca of female MACN-Ar 38155; F Spermatheca of female CNP-CE 1508. — Scale bars: 1 mm.

Remarks.

The female MACN-Ar 32688 listed above in other material of Euathlus basalticus sp. nov. had previously been designated as the paratype of Euathlus tenebrarum by Ferretti (2015). However, based on morphological examination, we found that this female is not conspecific with the male of E. tenebrarum. Our assignment to E. basalticus sp. nov. is based on diagnostic morphological differences observed in female specimens from the MACN collection, collected in localities near the type locality of E. tenebrarum. Moreover, the type locality of E. tenebrarum, Lago Curruhué Chico, is about 237 km distant from Copahue, where specimen MACN-Ar 32688 was collected.

Description male.

Male holotype (UNS M1122). — Coloration (in alcohol): Carapace brown, abdomen dark brown, lighter lines on dorsal femur, patellae and tibiae of palps and legs I–IV, maxillae and labium yellow, dark yellow sternum (Fig. 4A, B). — Coloration (in life): Legs I–IV and palps with light longitudinal lines on the dorsal surface of femora, patellae, and tibiae. Legs covered with long yellowish hairs (Fig. 7D). Whitish setae present on the margins of the cephalothorax and the proximal area of the chelicerae. Abdomen with reddish hairs anteriorly and yellowish hairs posteriorly. Spinnerets covered with orange hairs. Total length 18.07. — Prosoma: Carapace length 9.08, width 8.95. Anterior eye row procurved, posterior one recurved. Eye sizes and interdistances: AME 0.15, ALE 0.39, PME 0.24, PLE 0.25, AME-AME 0.30, AME-ALE 0.11, PME-PME 0.52, PME-PLE 0.07, ALE-PLE 0.22, OQ length 0.88, width 1.26. Clypeus 0.12. Fovea transverse, short, deep, slightly procurved, width 0.89. Labium length 1.12, width 1.56, with 65 cuspules. Maxillae (right/left) with 118/120 cuspules. Sternum length 4.44, width 3.58 (Fig. 4B). Chelicerae with 7 large teeth on promargin of furrow and 10 small teeth on the proximal area of retromargin. — Appendages: Tarsi I–IV densely scopulate with scopula entire, undivided. Metatarsi I 2/3 scopulated, II 1/2 scopulated, III 1/3 scopulated, IV 1/4 apically scopulated. Leg and palpal segments lengths in Table 1. Spination: Patellae of legs II–IV, femur of legs I and IV, tarsi of palps and legs I–IV, 0. Femora: palp 0-0-0-1 P; II 0-0-1-2 P; III 0-0-0-1 P, 0-1-1-1 R. Patellae: palp 0-0-1-0 P; I 0-0-0-1 V. Tibiae: palp 2-2-0-0 V, 0-1-0-0 P; I 2-0-2-0 V, 0-1-0-1 P, 1-0-0-0 R; II 2-2-0-4(ap) V, 0-1-0-1 P, 1-1-0-0 R; III 1-1-0-4(ap) V, 1-2-1-0 P, 1-2-1-0 R; IV 2-3-1-4(ap) V, 0-1-0-1 P, 0-2-1-0 R. Metatarsi: I 1-0-0-1 V; II 1-1-0-1(ap) V; III 2-1-1-3(ap) V, 1-0-1-1 P, 1-1-0-1 R; IV 2-0-2-3(ap) V, 1-0-1-1 P, 0-2-1-1 R. Metatarsus I straight. Tibial apophysis of leg I dark with two short branches, RB slightly longer than prolateral, both well-developed and originating from a common base, PB with a basal internal short strong spine, RB with a subapical internal short strong spine (Fig. 4C–E). Metatarsus I rests retrolaterally on the tibial apophysis when flexed. — Opisthosoma: Abdominal urticating setae patch large, reniform and central, with only type III urticating setae. Four spinnerets, PMS 0.7 long and PLS three segmented, basal segment 0.9 long, medial segment 0.8 long, and apical segment 1.2 long. —Genital organs: Palpal organ piriform, with a relatively broad embolus that tapers distally. The embolus is long and curved retrolaterally. Prolateral keels are unequally developed, with PI more developed than PS. The PI bears one or two well-developed teeth, located distally on the embolus but not entirely at the apex. An apical keel is also present (Fig. 5).

Figure 7.

Euathlus basalticus sp. nov. A, B Habitat at the type locality; C Alive paratype female (UNS M1492); D Alive holotype male (UNS M1122).

Table 1.

Download as

CSV

XLSX

Euathlus basalticus sp. nov., length of legs and palpal segments of holotype male (UNS M1122).

	Palp	Leg I	Leg II	Leg III	Leg IV
Femur	5.17	7.92	8.08	7.17	8.18
Patella	3.18	4.60	4.32	3.79	3.97
Tibia	4.01	6.49	6.10	5.54	6.60
Metatarsus	—	5.49	6.02	6.62	8
Tarsus	1.35	4.40	4.61	4.50	4.98
Total	13.71	28.9	29.13	27.62	31.73

Description female.

Female paratype (UNS M1492). — Coloration (in alcohol): carapace brown, margins of carapace yellow, yellowish lines on dorsal femur, patellae and tibiae of palps and legs I–IV, abdomen dark brown (Fig. 6A). — Coloration (in life): hole body reddish. Legs I–IV and palps exhibit distinct light longitudinal lines on the dorsal surfaces of the femora, patellae, and tibiae. Legs and abdomen are densely covered with long yellowish hairs. Margins of carapace, the base of the legs, and the proximal area of the chelicerae are light brown. Patch of urticating setae yellow (Fig. 7C). Total length 15.60. — Prosoma: Carapace length 6.52, width 6.18. Anterior eye row procurved, posterior one recurved. Eye sizes and interdistances: AME 0.12, ALE 0.34, PME 0.19, PLE 0.25, AME-AME 0.28, AME-ALE 0.11, PME-PME 0.47, PME-PLE 0.07, ALE-PLE 0.12, OQ length 0.96, width 1.14. Clypeus 0.12. Fovea transverse, short, deep, slightly procurved, width 0.41. Labium length 0.91, width 1.31 with 52 cuspules. Maxillae (right/left) with 107/103 cuspules. Sternum length 3.37, width 3.24 (Fig. 6B). Chelicerae with 9 well-developed teeth on promargin of furrow and 3 small teeth on the proximal area of retromargin. — Appendages: Tarsi I–IV densely scopulate, undivided. Metatarsi I 3/4 scopulated, II 1/2 scopulated, III 1/3 scopulated, IV 1/4 apically scopulated. Legs and palpal segments length in Table 2. Spination: Femora of legs I–IV, patellae and tarsi of palp and legs I–IV, 0. Femora: palp 0-0-0-1 P. Tibiae: palp 1-1-1-3(ap) V; I 0-1-0-0 V, 0-0-0-1(ap) P; II 0-0-0-3(ap) V; III 0-2-0-3 (ap) V, 0-1-1-0 P, 0-0-1-0 R; IV 0-1-0-2(ap) V, 0-1-1-1 P, 0-2-0-1 R. Metatarsi: I 0-1-0-1(ap) V; II 0-1-0-1(ap) V; III 2-2-0-3(ap) V, 1-1-0-1 P, 0-1-0-0 R; IV 1-2-1-4(ap) V, 0-1-0-1 P, 1-2-1-1 R. — Opisthosoma: Abdominal urticating setae patch large, reniform and central, with types III and IV present. Four spinnerets, PMS 0.74 long and PLS three segmented, basal segment 1.07 long, medial segment 0.62 long, and apical segment 0.82 long. — Genital organs: Spermatheca with two wide seminal receptacles with rounded shape facing upwards, each with a semi spheroid chamber pointing laterally, connected with a constricted duct, projecting from the lower outer margin of each receptacle (Fig. 6D).

Table 2.

Download as

CSV

XLSX

Euathlus basalticus sp. nov., length of legs and palpal segments of paratype female (UNS M1492).

	Palp	Leg I	Leg II	Leg III	Leg IV
Femur	3.56	5.27	4.74	4.01	5.45
Patella	2.15	2.98	2.88	2.44	2.74
Tibia	2.14	3.73	3.21	2.83	4.22
Metatarsus	—	2.79	2.74	3.22	4.70
Tarsus	2.57	2.66	2.62	2.81	3.19
Total	10.42	17.43	16.19	15.31	20.3

Etymology.

The specific name “basalticus” is a Latin adjective in the nominative singular. It refers to the strong association of this species with basaltic substrates, as specimens were exclusively found in areas dominated by basaltic rock formations. The name is derived from the Latin “basaltes” with the suffix “-icus,” meaning “belonging or pertaining to.”

Distribution and natural history.

These spiders are found in rocky formations (Fig. 7). These spiders inhabit rocky outcrops composed of andesitic and basaltic-andesitic lavas typical of the Caviahue–Copahue volcanic complex. They occur at elevations exceeding 1 600 m a.s.l., reaching near the summit of Copahue volcano at nearly 3 000 m a.s.l. (Varekamp et al. 2016). The lower montane zone shows the highest plant diversity due to abundant precipitation and moderate thermal conditions, with climax vegetation corresponding to Nothofagus forests and thickets mixed with the conifer Araucaria araucana (Mol.) Koch., which has its northernmost distributional limit in Argentina within this park. Key bioindicator species of the shrub-grass steppe ecotone include Festuca scabriuscula Philippi, Berberis empetrifolia Lamarck, and Ephedra frustillata Miers, creating the complex Andean-Patagonian ecosystem (Gandullo et al. 2004). Andesite and basaltic andesite are the predominant rock types of this basin (Cabrera et al. 2020) (Fig. 18).

3.3.3. Euathlus kupal sp. nov. Allegue and Ferretti

https://zoobank.org/976D5F7A-A3B3-4D54-BBD8-34C131-4272C4

Figures 8, 9, 10, 11, 18, Tables 3, 4

Type material.

Holotype: ARGENTINA • 1 ♂; Mendoza, Malargüe Department, Calmucó; 36.7832°S 69.8830°W; Apr. 1996; A. Giudicci leg.; MACN-Ar 46352. Paratype: ARGENTINA • 1 ♀; Mendoza, Malargüe Department, Salinillas; 36.2773°S 68.5858°W; 29 Jan. 1979; A. Roig leg.; MACN-Ar 46354.

Diagnosis.

Euathlus kupal sp. nov. can be distinguished from all known congeners by a unique combination of characters in males: tibial apophysis with two robust branches, the PB shorter than the RB and both bearing strong internal spines (Fig. 9), palpal organ slender with a long embolus with multiple small teeth along the curvature of the embolus: six well-defined teeth of varying sizes and three to four smaller teeth (Fig. 10). Females are diagnosed from all known species by the shape of the spermathecae, consisting of two low seminal receptacles with small mounds along the upper margin, each bearing a large semi-spheroid lateral chamber oriented downward, connected by a wide duct (Fig. 11D, E).

Description male.

Male holotype (MACN-Ar 46352). — Coloration (in alcohol): Carapace reddish with long whitish setae on margins, legs light brown/orange, abdomen brown with long yellowish setae, booklung openings yellowish (Fig. 8A–E). Total length 23.22. — Prosoma: Carapace length 12.32, width 11.47. Anterior eye row procurved, posterior one recurved. Eye sizes and interdistances: AME 0.20, ALE 0.48, PME 0.28, PLE 0.43, AME-AME 0.40, AME-ALE 0.19, PME-PME 0.74, PME-PLE 0.11, ALE-PLE 0.19, OQ length 1.33, width 1.68. Clypeus 0.16. Fovea transverse, deep, slightly recurved, width 1.30. Labium length 1.65, width 1.80, with 116 cuspules. Maxillae (right/left) with 110/120 cuspules. Sternum length 5.14, width 4.35 (Fig. 8B). Chelicerae with 7 well-developed teeth on promargin of furrow and 4 small teeth on the proximal area of retromargin. — Appendages: Tarsi I–IV densely scopulated, undivided. Metatarsi I fully scopulated, II 2/3 scopulated, III 1/2 scopulated, IV 1/4 apically scopulated. Leg and palpal segments lengths in Table 3. Spination: Patellae of palp and legs III and IV, tarsi of palp and legs I–IV, 0. Femora: palp 0-0-0-1 P; I 0-0-0-1 P; II 0-1-0-1 P, 0-1-0-0 R; III 1-1-0-1 P, 1-0-0-0 D; IV 0-1-0-0 P. Patellae: I 0-0-0-1 V. Tibiae: palp 1-1-0-1 P, 1-0-0-0 R; I 2-2-0-2(ap) V, 2-1-0-0 P, 2-1-0-0 R; II 3-3-0-3(ap) V, 1-1-1-0 P; III 2-1-0-3(ap) V, 2-2-1-0 P, 1-2-1-0 R; IV 2-1-0-3(ap) V, 1-2-1-0 P, 0-2-1-0 R. Metatarsi: I 1-0-0-1(ap) V; II 1-0-0-1(ap) V; III 3-2-0-2(ap) V, 1-1-0-1 P, 1-1-1-1 R; IV 3-2-1-3(ap) V, 1-1-0-1 P, 2-2-1-1 R. Metatarsus I straight. Tibial apophysis of legs I consists in two short well-developed black branches originating from a common base. Retrolateral branch slightly longer than prolateral, PB with a basal internal short strong spine, RB with a subapical internal short strong spine (Fig. 9). Metatarsus I rests retrolaterally on the tibial apophysis when flexed. — Opisthosoma: Abdomen dorsally with a rectangular patch of urticating setae with types III and IV. Four spinnerets, PMS 1.15 long and PLS three segmented, basal segment 1.56 long, medial segment 0.86 long, and apical segment 1.01 long. — Genital organs: Palpal organ piriform, elongated, with a relatively slender tegulum. Embolus long and slightly slender, starting to curve proximally to the tegulum in a retrolateral direction. Prolateral keels unequal, PS flat and weakly developed, PI well developed, bearing six well-defined teeth of varying sizes and three to four smaller teeth along the curvature of the embolus (Fig. 10).

Figure 8.

Euathlus kupal sp. nov. male holotype (MACN-Ar 46352). A. Carapace in dorsal view; B. Sternum in ventral view; C. Abdomen in dorsal view; D. Abdomen in ventral view. — Scale bars: 1 mm.

Figure 9.

Tibial apophysis of Euathlus kupal sp. nov. male holotype (MACN-Ar 46352). A Prolateral view; B Ventral view; C Retrolateral view. — Abbreviations: PB, prolateral branch; RB, retrolateral branch. — Scale bars: 1 mm.

Figure 10.

Palpal organ of Euathlus kupal sp. nov. male holotype (MACN-Ar 46352). A Retrolateral view; B Ventral view; C Prolateral view; D Dorsal view. — Abbreviations: A, apical keel; PI, prolateral inferior keel; PS, prolateral superior keel. Red arrow indicates the distal teeth on PI. — Scale bars: 1 mm.

Description female.

Female paratype (MACN-Ar 46354). — Coloration (in alcohol): Carapace and legs light brown/orange, abdomen brown (Fig. 11A). Total length 18.92. — Prosoma: Carapace length 8.87, width 7.91. Anterior eye row procurved, posterior one recurved. Eye sizes and interdistances: AME 0.14, ALE 0.44, PME 0.23, PLE 0.36, AME-AME 0.32, AME-ALE 0.18, PME-PME 0.59, PME-PLE 0.08, ALE-PLE 0.15, OQ length 0.83, width 1.46. Clypeus 0.20. Fovea transverse, short, slightly recurved, width 0.86. Labium length 1.21, width 1.43, with 53 cuspules. Maxillae (right/left) with 82/76 cuspules. Sternum length 4.16, width 3.66 (Fig. 11B). Chelicerae with 7 large teeth on promargin of furrow and 4 small teeth on the proximal area of retromargin. — Appendages: Tarsi I-IV densely scopulated, undivided. Metatarsi I 2/3 scopulated, II 1/2 scopulated, III 1/3 scopulated, IV 1/4 apically scopulated. Leg and palpal segments lengths in Table 4. Spination: Femur of leg IV, patellae and tarsi of palp and legs I–IV, 0. Femora: palp 0-0-0-1 P; I 0-0-0-1(ap) P, II 0-0-0-1(ap) P, 0-0-0-1 R. Tibiae: palp 1-2-0-3(ap) V, 0-0-0-1 R; I 0-1-0-0 V, 0-0-0-1(ap) P; II 0-1-0-1(ap) V, 0-0-0-1(ap) P; III 0-2-0-2 (ap) V, 0-1-1-0 P, 1-0-1-0 R, IV 0-2-1-3(ap) V, 0-0-1-0 P, 1-0-1-0 R. Metatarsi: I 0-1-0-1(ap) V; II 0-1-0-1(ap) V; III 2-2-0-3(ap) V, 1-1-0-1 P, 1-1-0-1 R; IV 2-2-1-3(ap) V, 0-1-0-1 P, 1-2-1-1 R. — Opisthosoma: Abdomen with large oval urticating setae patch with types III and IV. Four spinnerets, PMS 0.68 long and PLS three segmented, basal segment 1.63 long, medial segment 0.95 long, and apical segment 1.11 long. — Genital organs: Spermatheca with two low seminal receptacles with mounds on its upper margin, each with a large semi-spheroid lateral chamber oriented downward, connected with a wide duct without noticeable constriction (Fig. 11D, E).

Figure 11.

Euathlus kupal sp. nov. female paratype (MACN-Ar 46354). A Carapace in dorsal view; B Sternum in ventral view; C Abdomen in dorsal view; D Spermatheca; E Spermatheca drawing. — Scale bars: 1 mm.

Table 3.

Download as

CSV

XLSX

Euathlus kupal sp. nov., length of leg and palpal segments of holotype male (MACN-Ar 46352).

	Palp	Leg I	Leg II	Leg III	Leg IV
Femur	6.61	8.85	9.85	7.72	9.77
Patella	3.87	5.60	5.29	4.39	5.02
Tibia	5.70	8.46	8.52	7.29	9.39
Metatarsus	—	6.80	7.77	8.80	10.28
Tarsus	1.60	5.89	5.20	5.80	5.41
Total	17.78	35.6	36.63	34	39.87

Table 4.

Download as

CSV

XLSX

Euathlus kupal sp. nov., length of leg and palpal segments of female paratype (MACN-Ar 46354).

	Palp	Leg I	Leg II	Leg III	Leg IV
Femur	4.47	6.12	7.39	5.91	7.14
Patella	3.21	4.10	3.54	3.33	3.57
Tibia	3.28	5.30	5.09	4.45	6.08
Metatarsus	—	4.15	3.90	4.93	7.07
Tarsus	2.80	2.90	3.36	3.07	3.71
Total	13.76	22.57	23.28	21.69	27.57

Etymology.

The specific name “kupal” is a noun in the nominative singular, used in apposition to the generic name. It is derived from the Mapuche language, where it means ‘family’ or ‘lineage.’ This term honors the author’s family and also serves as a recognition of the Mapuche people who historically inhabited the region where this species was discovered.

Distribution and natural history.

The region where this species inhabit is characterized by arid and cold conditions, with large daily and annual temperature ranges and scarce precipitation with a mean annual precipitation of about 360 mm. The average annual temperature is 12°C. Winters are cold, with average temperatures around 5°C, while summers are mild, averaging 20°C (Tello et al. 2021). This area comprises an overlap of three floristic districts: Monte Occidental, Patagonian Steppe, and the High Andean region. This ecotone condition, combined with the great variety of topographies and substrates present, represents a relevant feature from a botanical point of view. It is possible to find a wide variety of flora, including marginal elements from the aforementioned floristic districts and a significant number of endemic species, such as Sporobolus mendocinus Méndez and Adesmia glandulifolia Steibel and Ulibarri (Prina et al. 2003) (Fig. 18).

3.3.4. Euathlus susanae sp. nov. Peralta-Seen, Allegue and Ferretti

https://zoobank.org/81E9D9A5-ECFB-439B-A1C4-F03304-360E9B

Figures 12, 13, 14, 15, 18, Tables 5, 6

Type material.

Holotype: ARGENTINA • 1 ♂; La Pampa, Chical Co Department, Reserva Provincial Cerro Negro; 36.0569°S 68.2816° W; 1141 m a.s.l.; 21 Oct. 2022; G. San Blas, F. Diez and N. Peralta-Seen leg.; UNS M1078. Paratype: ARGENTINA • 1 ♀; La Pampa, Chical Co Department, Reserva Provincial Cerro Negro; 36.0566°S 68.2830°W; 1166 m a.s.l.; 20 Oct. 2022; N. Peralta-Seen leg.; UNS M1396.

Other material.

ARGENTINA • 1 ♂; La Pampa, Chical Co Department, Reserva Provincial Cerro Negro; 36.0574°S 68.2831°W; 1165 m a.s.l.; 21 Oct. 2022; G. San Blas, F. Diez and N. Peralta-Seen leg.; UNS M1068. • 2 ♀♀; Mendoza, Malargüe Department, Agua Escondida; 36.1538°S 68.2974°W; 20–22 Oct. 2022; N. Peralta-Seen leg.; UNS M1493, M1509.

Diagnosis.

Euathlus susanae sp. nov. can be distinguished from all known congeners by the following combination of characters: tibial apophysis with two robust branches, the PB shorter than the RB and both bearing strong internal spines, males with a palpal organ similar in general morphology to that of E. condorito, but it can be distinguished by a more developed prolateral inferior keel (PI) with stronger and distally serrated teeth (Figs 12D, 13). Females are diagnosed from congeners by their spermathecae, which consist of two wide seminal receptacles projecting straight upward, each with pronounced inner lobes and two large semi-spheroid lateral chambers pointing upwards (Fig. 14D, E).

Figure 12.

Euathlus susanae sp. nov. male holotype (UNS M1078). A Carapace in dorsal view; B Sternum in ventral view; C Abdomen in dorsal view; D Tibial apophysis in prolateral view. — Abbreviations: PB, prolateral branch; RB, retrolateral branch. — Scale bars: 1 mm.

Figure 13.

Palpal organ of Euathlus susanae sp. nov. male holotype (UNS M1078). A Prolateral view; B Ventral view. — Abbreviation: PI, prolateral inferior keel. Red arrow indicates the teeth on the PI. — Scale bars: 1 mm.

Figure 14.

Euathlus susanae sp. nov. female paratype (UNS M1396). A Carapace in dorsal view; B Sternum in ventral view; C Abdomen in dorsal view; D Spermatheca; E Spermatheca drawing. — Scale bars: 1 mm.

Description male.

Male holotype (UNS M1078). — Coloration (in alcohol): carapace dark brown with small grey and black setae and long golden setae more abundant on the margins and on dorsal chelicerae (Fig. 12A); legs brownish; abdomen with black setae and long orange setae and a large patch of orange setae on the anterior-dorsal face; sternum, coxa, and trochanter reddish (Fig. 12B, C). — Coloration (in life): Orange hairs on legs, margins of carapace, chelicerae, and proximal abdomen. Ventral body with dark brown/black coloration (Fig. 15D, E). Total length 28.97. — Prosoma: Carapace length 12.32, width 11.32. Anterior eye row slightly procurved, posterior one recurved. Eye sizes and interdistances: AME 0.31, ALE, 0.59, PME 0.34, PLE 0.56, AME-AME 0.31, AME-ALE 0.19, PME-PME 0.75, PME-PLE 0.13, ALE-PLE 0.19, OQ length 1.41, width 1.75, clypeus 0.31. Fovea transverse, straight, width 1.33. Labium length 1.56, width 2.06, with 76 cuspules. Maxillae (right/left) 144/151 cuspules. Sternum length 6.11, width 5.55 (Fig. 12B). Right chelicerae with 7 well-developed teeth on promargin of furrow and 9 small teeth on the proximal area of furrow, left chelicerae with 7 well-developed teeth and 1 small located distally on the promargin of furrow and 9 small teeth on the proximal area of furrow. — Appendages: Tarsi I–IV densely scopulated, undivided. Metatarsi I fully scopulated, II 1/2 scopulated, III 1/3, IV 1/4 apically scopulated. Leg and palpal segments lengths in Table 5. Spination: Femora and patellae of palps and legs I–IV, tarsi of palp and legs I–IV, 0. Femora: II 1-3-1 P, III 1-1-1-1 P. Tibiae: palp 2-2 V, 1-2 P; I 2-1-1 V, 1-1 P; II 3-2-3 V, 1-1 P; III 2-2-3 V, 1-1 P, 1-1 R; IV 2-2-2 V, 1-1 P, 1 R. Metatarsi: I 1-1 V; II 1 V; III 1-1-2 V, 1-1-1 P, 1-1-1 R; IV 1-1-1 V, 1-1-1-1 P, 1-1 R. Metatarsus I slightly curved. Tibial apophysis of legs I with two short well-developed branches, retrolateral branch slightly longer than prolateral; PB and RB with an internal subapical strong and short spine (Fig. 12D). Metatarsi I flexes to the retrolateral branch of the tibial apophysis. — Opisthosoma: Abdomen with oval central urticating setae patch with types III and IV. Four spinnerets, PMS 1.1 long and PLS three segmented, basal segment 2.1 long, medial segment 1.2 long and apical segment 1.5 long. — Genital organs: Palpal organ piriform without constriction between tegulum and embolus. Embolus curving retrolaterally, prolateral keels unequal; PS flat and less developed, PI well developed with 6–9 small teeth along the retrolateral face of the curvature of embolus (Fig. 13).

Figure 15.

Euathlus susanae sp. nov. A, B Habitat at the type locality; C Alive paratype female (UNS M1396); D Alive holotype male (UNS M1078); E Mating position.

Table 5.

Download as

CSV

XLSX

Euathlus susanae sp. nov. length of leg and palpal segments of holotype male (UNS M1078).

	Palp	Leg I	Leg II	Leg III	Leg IV
Femur	6.33	11.21	11.10	9.44	11.43
Patella	3.89	5.55	5.77	5.44	4.55
Tibia	5.33	9.55	9.44	6.66	10.55
Metatarsus	—	8.21	8.66	9.10	11.54
Tarsus	2.33	5.88	5.33	5.77	5.55
Total	17.87	40.40	40.29	36.41	43.62

Table 6.

Download as

CSV

XLSX

Euathlus susanae sp. nov., length of leg and palpal segments of paratype female (UNS M1396).

	Palp	Leg I	Leg II	Leg III	Leg IV
Femur	7.77	10.10	9.32	8.88	10.55
Patella	4.55	6.33	5.77	4.55	5.55
Tibia	5.55	8.44	7.77	6.66	9.10
Metatarsus	0.00	5.55	5.55	7.22	9.88
Tarsus	4.44	4.00	3.89	4.33	4.55
Total	22.31	34.41	32.30	31.64	39.63

Description female.

Female paratype (UNS M1396). — Coloration (in alcohol): Carapace dark brown covered with black and grey short hairs and golden long hairs which are more abundant on the margins and on dorsal chelicerae (Fig. 14A), legs brownish with evident patellar lines, abdomen dark brown with short black hairs and long golden hairs on the dorsum; sternum, coxa and trochanter light brown (Fig. 14B, C). — Coloration (in life): Iridescent orange to pink hairs at the base of the legs, chelicerae, and carapace. Longer pink hairs on the legs, margins of the carapace, and distal abdomen. The proximal abdomen is covered with long orange hairs. The ventral face of body is very dark, almost black (Fig. 15C, E). Total length 36.63. — Prosoma: Carapace length 13.88, width 12.65. Anterior eye row procurved, posterior one recurved. Eye sizes and interdistances: AME 0.31, ALE 0.63, PME 0.41, PLE 0.50, AME-AME 0.47, AME-ALE 0.13, PME-PME 0.88, PME-PLE 0.13, ALE-PLE 0.19, OQ length 1.47, width 2.09, clypeus 0.34. Fovea transverse, straight, width 1.35. Labium length 1.67, width 2.78 with 125 cuspules. Maxillae (right/left) with 137/139 cuspules. Sternum length 8.33, width 6.66 (Fig. 14B). Right chelicerae with 8 large teeth on promargin of furrow and 6 small teeth on the proximal area of furrow, left chelicerae with 7 large teeth on the promargin of furrow and 6 small teeth on the proximal area of furrow. — Appendages: Tarsi I–IV densely scopulated, undivided. Metatarsi I 3/4 scopulated, II 2/3 scopulated, III 1/3 scopulated, IV 1/4 apically scopulated. Legs and palpal segments lengths in Table 6. Spination: Femora and patellae of legs I–IV, patellae of palps, 0. Femora of palp: 1 P. Tibiae: palp 2-2-3 V, 1 R; I 2 V; II 1-2 V; III 2-1-2 V, 1 P; IV 2-2 V, 1-1 P. Metatarsi: I 1 V; II 1-1 V; III 2-1-2 V, 1-1-1 P, 1-1-1 R; IV 1-1-2-3 V, 1-1-1-1 P, 1-1 R. — Opisthosoma: Abdomen with large “apple” shaped urticating setae patch with types III and IV. Four spinnerets, PMS 1.2 long and PLS three segmented, basal segment 2 long, medial segment 1.6 long, and apical segment 1.3 long. — Genital organs: Spermatheca with wide seminal receptacles, upper margin smooth, with pronounced oval margins towards the inner part, and with two semi-spheroid lateral chambers pointing upwards (Fig. 14D, E).

Etymology.

This species is a noun in the genitive case, named after Susana Seen, the mother of the collector, whose unconditional support made the discovery of this species possible.

Distribution and natural history.

This species is distributed in northwestern La Pampa province and southeastern Mendoza province. Euathlus susanae sp. nov. was found in the Protected Provincial Area Cerro Negro, La Pampa province (Fig. 15A), and in the locality of Agua Escondida, Mendoza province (Fig. 18). The Cerro Negro reserve contains the “Cerro Negro”, which is a basaltic volcano dated from 4.71 Ma that elevates 1167 m a.s.l. and its summit represents the highest geographical point in La Pampa province (Bertotto et al. 2022). The volcano is surrounded by a middle altitude steppe, located in the center of the Monte biogeographical province (elevation of about 1100 m), which is dominated by Larrea divaricata Cav. 1800. The specimens of Euathlus susanae sp. nov. were found in burrows and shelters under vesicular volcanic agglomerates. One adult female and two immature males were found in October (spring in the southern hemisphere). The immature males molted three months after capture, in late February (summer in the southern hemisphere). Individuals from Agua Escondida (Fig. 15B), were found in burrows and shelters under rocks of the Agua Escondida Formation, composed by quartz sandstones of Upper Carboniferous age (elevation of about 1095 m) (González Díaz 1972), also located in the Monte biogeographical province.

Sexual behavior.

We observed two mating events in Euathlus susanae sp. nov. One event was performed by a male and a female from Cerro Negro Reserve, La Pampa province. The courtship was initiated by the male, who performed rhythmic leg tapping with legs I and vibrations with leg III, lasting a total of 11 minutes. The male then approached the female, making contact toward her front legs with his legs I and II. After that, the female oriented to the position of the male while performing high-frequency leg tapping with legs I and palps over the substrate. The male repeated leg tapping with legs I, prompting the female to approach. The male then grasped his first pair of legs around the female’s chelicerae and elevated her to access the genital opening. Once the female was lifted, the male performed palpal boxing (alternating vertical movements of the pedipalps in contact with the female’s sternum). A single palpal insertion event was observed, lasting about 47 seconds. After disengagement, the male performed leg tapping with legs I on the female, but she walked away.

In the second event, a male from Cerro Negro, La Pampa and a female from Agua Escondida, Mendoza successfully mate. The male initiated courtship by vibrating leg III, followed by leg tapping with legs I, or with legs I and II simultaneously. This courtship phase lasted 4.16 minutes, during which the male approached the female slowly while continuing these displays. Upon reaching the female, the male tapped her leg IV (as she was oriented in the opposite direction), causing her to turn towards him. He attempted to grasp the tibial apophysis on her chelicerae, but the female became unstable, preventing clasping. The male initiated the courtship again for an additional 5.21 minutes, performing leg tapping, after which the female approached. At this instance, the male successfully clasped the tibial apophysis into the chelicerae of the female and then elevated her. The copulation event lasted 4.1 minutes. The male began with palpal boxing, followed by insertion of the right palp for approximately 0.6 minutes. He then attempted an insertion of the left palp but was unsuccessful, after trying again, the left palp was successfully inserted for 1 minute. After, he performed a second left palp insertion, which lasted 1.85 minutes. After disengagement, the male performed leg tapping on the female’s front legs; after this movement, the female turned away.

3.3.5. Euathlus tenebrarum Ferretti, 2015

Figures 16, 17, 18, Table 7

Type material.

Holotype: ARGENTINA • 1 ♂; Neuquén, Huiliches Department, next to Curruhué Chico lake; 39.9078°S 71.3328°W; 1042 m a.s.l.; 28 Oct. 2011; L. Schwerdt leg.; MACN-Ar 32687.

Other material.

ARGENTINA • 4 ♀♀; Neuquén, Huiliches Department, Junín de los Andes; 39.9461°S 71.0730°W; 27 Feb. 1968; Maury and N. Mullet leg.; MACN-Ar 45254, 47712, 47781, 47806. • 1 ♂; same data as preceding; MACN-Ar 46231.

Amended diagnosis.

Male differs from the other Euathlus species by a tibial apophysis with slightly developed branches almost of equal sizes (Fig. 16A–C) and by the strong curvature of the embolus, reaching almost 90° between embolus and tegulum (Fig. 16D–H). The PB has three strong spines, two internal ones, one of which is located more basally and the other subapical, and one external spine. Females differ from other congeners by the shape of the spermathecae, consisting of two high sub-quadrate seminal receptacles with upper margin slightly mounded; each with a lateral wide oval chamber connected with a wide duct (Fig. 17).

Figure 16.

Euathlus tenebrarum male (MACN-Ar 46231). A Tibial apophysis in prolateral view; B Tibial apophysis in ventral view; C Tibial apophysis in retrolateral view; D Palpal organ in retrolateral view; E Palpal organ in ventral view; F Palpal organ in prolateral view; G Palpal organ in dorsal view. — Abbreviations: PB, prolateral branch; RB, retrolateral branch. Red arrow indicates the distal teeth on PI. — Scale bars: 1 mm.

Figure 17.

Euathlus tenebrarum female (MACN-Ar 47712). A Carapace in dorsal view; B Sternum in ventral view; C Abdomen in dorsal view; D Spermatheca; E Spermatheca of an additional female (MACN-Ar 47781). — Scale bars: 1 mm.

Description female.

Female (MACN-Ar 47712). — Coloration (in alcohol): reddish brown, two yellowish lines on femora, patella, and tibia of palps and legs I-IV. Total length 25.52. — Prosoma: Carapace length 10.60, width 9.46 (Fig. 16A). Anterior eye row procurved, posterior one recurved. Eyes sizes and interdistances: AME 0.16, ALE 0.31, PME 0.12, PLE 0.39, AME-AME 0.42, AME-ALE 0.16, PME-PME 0.74, PME-PLE 0.08, ALE-PLE 0.23, OQ length 1.19, width 1.60. Clypeus absent. Fovea transverse, slightly procurved, width 1.55. Labium length 1.46, width 1.73 with 91 cuspules. Sternum length 4.87, width 4.56 (Fig. 16B). Chelicerae with 6 well-developed teeth on promargin of furrow and 7 teeth on the proximal area on retromargin. — Appendages: Tarsi I–IV densely scopulated and entire. Metatarsi I fully scopulated, II 2/3 scopulated, III 1/2 scopulated, IV 1/4 apically scopulated. Leg and palpal segments lengths in Table 7. Spination: Femora, patellae, and tarsi of palps and legs I–IV, 0. Tibiae: palp 0-0-0-2(ap) V, 1-0-1-1(ap) P; I 0-0-1-2(ap) V, 0-0-0-1(ap) P; II 0-1-0-3(ap) V; III 0-1-0-3 (ap) V, 0-0-1-0 P; IV 0-1-0-0 V, 0-1-0-1(ap) P, 0-1-1-1(ap) R. Metatarsi: I 1-0-0-1(ap) V; II 0-1-0-0 V; III 1-2-0-3(ap) V, 0-1-0-1 P, 0-0-0-1 R; IV 1-2-1-3(ap) V, 0-1-0-1 P, 1-1-3-1 R. — Opisthosoma: Types III and IV urticating setae present. Four spinnerets, PMS 0.92 long and PLS three segmented, basal segment 1.94 long, medial segment 1.26 long and apical segment 1.12 long. — Genital organs: Spermatheca consisting of two high seminal receptacles, sub-quadrate, with upper margin not straight, with a few small mounds; each with a lateral wide oval chamber connected with a wide duct (Fig. 16D).

Remarks.

The female specimen previously designated as a paratype of Euathlus tenebrarum (MACN-Ar 32688) is herein reassigned to Euathlus basalticus sp. nov. This decision is based on a comparative analysis of additional specimens deposited in the MACN collection, including three females (MACN-Ar 47712, 47806, 47781) and one male (MACN-Ar 46231) (Fig. 17) from Junín de los Andes. The male matches with the morphology described for E. tenebrarum by Ferretti (2015), while the females show clear morphological differences. Furthermore, during a field campaign conducted in November 2023, we surveyed localities near the record of the aforementioned paratype female collecting one adult male (UNS M1122), whose morphology differs considerably from that of E. tenebrarum and is consistent with the diagnosis of Euathlus basalticus sp. nov.

Distribution.

Previously known from the Huiliches Department, Neuquén province, Argentina. The species has been recorded near Curruhué Chico Lake (type locality) (Ferretti 2015). From this work, recorded in Junín de los Andes, Neuquén province (Fig. 18).

Figure 18.

Distribution map of known Euathlus species in South America, with a close-up view showing the three new species described in this study: Euathlus basalticus sp. nov., E. kupal sp. nov., and E. susanae sp. nov. Chile teinted in orange, Argentina in green, Peru in violet.

Table 7.

Download as

CSV

XLSX

Euathlus tenebrarum female, length of leg and palpal segments (MACN-Ar 47712).

	Palp	Leg I	Leg II	Leg III	Leg IV
Femur	4.88	6.14	6.79	5.76	7.41
Patella	3.70	4.25	4.20	3.19	3.79
Tibia	3.26	4.89	4.56	4.22	5.56
Metatarsus	—	3.94	4.08	4.46	6.11
Tarsus	3.58	3.22	3.20	3.20	4.16
Total	15.42	22.44	22.83	20.83	27.03

4. Discussion

The genus Euathlus seems to be more diverse than previously thought because although most species described share a common morphology regarding their genitalic features, a considerable variation among them actually exists. For example, females have a spermatheca that typically consist of wide seminal receptacles with lateral chambers; however, these structures vary widely in shape, position, and orientation. In addition, males possess palpal bulbs with a consistent architecture, yet exhibiting marked interspecific differences. The embolus varies from thinner to thicker forms, and may be either slightly or strongly curved, always directed retrolaterally. The distal portion of the embolus bears a PI keel, which may present teeth or serrated edges; an apical keel can be present or absent, and accessory keels may vary in their presence and development. Secondary genitalic structures, such as the tibial apophysis, also show notable variation, ranging from one to two branches, with differences in thickness and degree of development. In addition, the number and morphology of the spines associated with the tibial apophysis vary significantly among species (Allegue and Ferretti 2025; Ferretti 2015; Perafán and Pérez-Miles 2014; Ríos-Tamayo 2020; Taucare-Ríos et al. 2025).

Compounding the taxonomic challenges in Euathlus is the ontogenetic development of the spermatheca. The structures are often homogeneous in immature females, making species diagnosis difficult until the specimen reaches full maturity and the spermathecae acquire their definitive morphology. Consequently, these structures may vary significantly throughout the individual’s development, preventing accurate descriptions, identifications, and comparisons among species (Schwerdt et al. 2021).

Regarding the cladistic analysis, although some clades exhibit high support values in the majority-rule consensus tree (e.g., 100%), they are supported exclusively by homoplasies. This indicates that, despite their stability across the trees, these groupings are not underpinned by unique morphological synapomorphies. Such results underscore the limitations of the morphological dataset, including the scarcity of clear synapomorphies, the recurrence of certain character states, and possible convergences. Nevertheless, the analysis recovered an interesting clade within Euathlus, supported by character 16 (the presence of a ventral spine on the retrolateral branch of the tibial apophysis) as a synapomorphy that distinguishes a clearly cordilleran clade (including all Chilean species, except for E. diamante, which is found in Argentina) from another group distributed across the cordillera, precordillera, and steppe (with Argentinean and Peruvian species). The latter group (E. tenebrarum, E. kupal sp. nov., E. basalticus sp. nov., E. sagei, E. vanessae, E. susanae sp. nov., E. ameghinoi, E. ventus) is further supported by two additional synapomorphies: the presence of an apical keel (character 4) and the presence of teeth on the prolateral inferior (PI) keel of the embolus (character 7).

In this analysis, the genus Euathlus was recovered as paraphyletic, including representatives of the genus Phrixotrichus. Although these two genera were clearly diagnostic and recovered as two different lineages in previous morphological cladistics analyses (Perafán and Pérez-Miles 2014; Ferretti 2015; Allegue and Ferretti 2025), we must take into account the complex and long-standing taxonomic history which includes multiple transfers between these genera. For example, Phrixotrichus was originally considered as a junior synonym of Euathlus by Schmidt (1996), but was later revalidated by Perafán and Pérez-Miles (2014). Taxonomic confusion between these groups has persisted over time. For instance, Strand (1908) described the genus Ashantia, which Gallon (2005) later considered a junior synonym of Euathlus. However, it is now recognized that Ashantia latithorax corresponds to Phrixotrichus vulpinus, and Ashantia is currently treated as a junior synonym of Phrixotrichus. Then, why did our study not recover both genera as distinct clades? Arguably, both the cladistic analyses from Perafán and Pérez-Miles (2014) and Ferretti (2015) included just less than half of the Euathlus species that we know to date, thus the full picture of the variation of the genitalic features and secondary sexual characters were underrepresented. Indeed, the morphologies observed from many taxa seem to indicate that some characters are more informative for their grouping, for example, the shape of the tibial apophysis or the embolus from the palpal organ, instead of the presence of one/two urticating setae patches, which has been used traditionally to discriminate between these two genera. Then, we could have taken the action of synonymizing Phrixotrichus with Euathlus from the cladistics analysis, but for now, we prefer to be cautious. One reason is because to date, there are still no mitochondrial fragment sequences available to test the monophyly or distinctiveness of Phrixotrichus in relation to Euathlus and testing the monophyly of these genera would require analyses based on multiple independent loci.

A striking result from the molecular phylogenetic analysis was the non-grouping of the sequences of Euathlus basalticus sp. nov. in a clade, as one of the sequences was grouped closely related with E. sagei, while the other remained outside that clade. This clade ((E. sagei + E. basalticus sp. nov) E. basalticus sp. nov) is well supported. This unexpected pattern of intraspecific polyphyly matches another findings in other mygalomorph taxa. Indeed, Hamilton et al. (2024) documented a similar case in Aphonopelma jacobii Hamilton and Hendrixson, 2024, where mitochondrial haplotypes from different populations were split across divergent clades, with some nested within A. marxi (Simon, 1891), rendering it paraphyletic. This phenomenon, known as gene-tree/species-tree incongruence, occurs when gene trees reveal that alleles from one species are more closely related to those from another species than to conspecific alleles. Such patterns are often attributed to ancient admixture and asymmetric mitochondrial introgression (Horoiwa et al. 2021) and have been reported in other theraphosid genera (Hamilton et al. 2016). This incongruence may also result from incomplete lineage sorting or an underestimation of the extent of gene flow among populations (Funk and Omland 2003).

Despite the mitochondrial incongruence observed here, we believe that the clear morphological differences between E. basalticus sp. nov. and E. sagei support their recognition as distinct species. Nevertheless, the presence of divergent mitochondrial lineages within a single morphologically diagnosable species may reflect similar evolutionary processes. Past climatic fluctuations and habitat shifts in the Andean and Patagonian regions could have facilitated secondary contact and introgression between lineages now occupying disjunct habitats (Sérsic et al. 2011). Further sampling across the distribution range of E. basalticus sp. nov., combined with multi-locus genomic analyses, are required to unveil the extent of mitochondrial introgression, test for potential cryptic diversity, and clarify the species’ evolutionary history.

It is important to note that sequences for many described species are still lacking. Future efforts will focus on incorporating additional molecular markers, particularly nuclear genes, which are essential for a more robust phylogenetic framework. Despite the current limitations in taxon and marker sampling, we consider it valuable to present the available molecular data, as the results demonstrate that the studied lineages are distinct from previously known Euathlus sequences and also from outgroup taxa.

Euathlus susanae sp. nov. is distributed in two different localities: Agua Escondida, Mendoza, and the Cerro Negro Reserve, La Pampa. Individuals from both sites cluster together in the molecular analysis, supporting the hypothesis that they belong to the same species. Morphologically, females from both populations are similar, particularly in the shape of the spermatheca. Unfortunately, males from Agua Escondida are unknown, thus further morphological comparisons were not possible to conduct. Additionally, mating trials were performed to explore potential reproductive barriers. In these trials, males and females from different populations successfully performed courtship and copulation, indicating the absence of prezygotic isolation, at least at the level of courtship behavior, as similarly interpreted for other theraphosid spiders (Costa and Pérez-Miles 2002). However, some specific behavioral differences were observed e.g. during the intraspecific trial within Cerro Negro specimens, the female responded quickly and positively to the male’s courtship. In contrast, from the trial using individuals from different localities, the female initially showed a more reluctant behavior, taking more time to accept the male. Nevertheless, mating occurred, reinforcing the hypothesis that these populations are reproductively compatible. The combined molecular, morphological, and behavioral evidence suggests that E. susanae sp. nov. represents a single species composed of at least two geographically distinct but reproductively connected populations.

Morphologically, it is important to note that Ríos-Tamayo (2020) suggested the existence of morphological differences between males from Caviahue (now described as Euathlus basalticus sp. nov.) and those of E. tenebrarum from Lago Curruhué Chico. Based on our comparisons of specimens of E. basalticus sp. nov. and E. tenebrarum, we were able to clearly differentiate them. Furthermore, we assigned females to E. tenebrarum from other localities near the type locality, along with a male that exhibited morphological characteristics consistent with those already described for the species. In E. basalticus sp. nov., males possess only type III urticating setae, whereas females have both types III and IV. The absence of type IV setae in males may be associated with the loss of structures related to passive defense. According to Ortiz-Villatoro et al. (2020) and Russi and Pérez-Miles (2023), type IV setae are mainly incorporated into the ootheca and moulting mats, suggesting a role in passive defense against arthropods or phorid larvae rather than in active defense against vertebrate predators. Males, which lead a more mobile lifestyle and do not construct oothecae, would not require this type of setae, relying instead on type III for active defense. This pattern may therefore reflect a sexually dimorphic adaptation linked to differences in ecology and behavior between sexes.

The distribution pattern of Euathlus also deserves further attention. Many species, including some described in this study, inhabit small rocky relicts, some located far from the Andean Cordillera. These isolated and spread populations led us to think about the historical and ecological processes shaping the current distribution of the genus. Although the present work focuses on taxonomic aspects, arguably, these biogeographical patterns may provide valuable context for future studies on diversification and endemism within Euathlus.

Overall, both the cladistic and molecular analyses highlight the complex evolutionary history of Euathlus, revealing patterns of morphological convergence, taxonomic uncertainty, and possible historical gene flow. While these approaches provide complementary evidence, the limited sampling and absence of molecular data for some key species preclude definitive taxonomic conclusions. Future studies integrating expanded molecular datasets, particularly multi-locus information, alongside with more comprehensive morphological analyses, will be essential to fully resolve the phylogenetic relationships and species boundaries within the genus.

5. Declarations

Authors’ contributions. Maite Allegue: conceptualization, formal analyses, investigation, methodology, data curation, visualization, writing – original draft preparation. — Nicolás Peralta-Seen: investigation, writing – reviewing and editing. — Nelson Ferretti: conceptualization, supervision, investigation, writing – reviewing and editing, project administration, funding acquisition.

Conflict of interest. The authors do not have any conflict of interest to declare.

6. Acknowledgments

We are grateful to Diego Bambozzi, Justina Panchuk, Leonela Schwerdt, Micaela Nicoletta, Fernando Diez, and Germán San Blas who helped to collect specimens in the field. Thanks to Subsecretaría de Ambiente and Dirección de Recursos Naturales, Gobierno de La Pampa, for collecting permits in the proyect N°50, resolution 37/2022 CD, supported by Facultad de Ciencias Exactas y Naturales (Universidad Nacional de La Pampa). Thanks to the Secretariat for Territorial Development and Environment of the Province of Neuquén for collecting permits in the proyect N°8903-006471/2023. Funding was provided by the National Agency of Research Promotion, Technical Development, and Innovation (Agencia I + D + i) through the grant PICT 2021-0407 and Secretaría General de Ciencia y Tecnología of the Universidad Nacional del Sur for the grant PGI24/ZB87.

7. References

Allegue M, Ferretti N (2025) Hidden in the plains: two new extra-andean species of Euathlus (Mygalomorphae, Theraphosidae) from Argentina with comments on their sexual behaviour. Zoologica Scripta 54(2): 213–218. https://doi.org/10.1111/zsc.12699

Bertani R (2000) Male palpal bulbs and homologous features in Theraphosinae (Araneae, Theraphosidae). Journal of Arachnology 28(1): 29–42. https://doi.org/10.1636/0161-8202(2000)028[0029:MPBAHF]2.0.CO;2

Bertani R (2001) Revision, cladistic analysis, and zoogeography of Vitalius, Nhandu, and Proshapalopus, with notes on other theraphosine genera (Araneae: Theraphosidae). Arquivos de Zoologia 36(3): 265–356.

Bertani R (2002) Morfologia e evolução das cerdas urticantes em Theraphosidae (Araneae) [Doctoral dissertation]. University of São Paulo.

Bertotto GW, Bernardi MI, Richter AJ (2022) Volcanismo en la provincia de La Pampa: aportes teóricos y didácticos. Editorial de la Universidad Nacional de La Pampa, Santa Rosa.

Cabrera JM, Temporetti PF, Pedrozo FL (2020) Trace metal partitioning and potential mobility in the naturally acidic sediment of Lake Caviahue, Neuquén, Argentina. Andean Geology 47(1): 46–60. http://dx.doi.org/10.5027/andgeoV47n1-3200

Candia-Ramírez DT, Francke OF (2021) Another stripe on the tiger makes no difference? Unexpected diversity in the widespread tiger tarantula Davus pentaloris (Araneae: Theraphosidae: Theraphosinae). Zoological Journal of the Linnean Society 192(1): 75–104. https://doi.org/10.1093/zoolinnean/zlaa107

Cooke JA, Roth VD, Miller F (1972) The urticating hairs of Theraphosidae. American Museum Novitates 2498: 1–43.

Costa FG, Pérez-Miles F (2002) Reproductive biology of Uruguayan theraphosids (Araneae, Mygalomorphae). The Journal of Arachnology 30(3): 571–587. https://doi.org/10.1636/0161-8202(2002)030[0571:RBOUTA]2.0.CO;2

Ferretti N (2015) On three new Euathlus tarantulas from Argentina and cladistic analysis of the genus. Journal of Arachnology 43(3): 313–326. https://doi.org/10.1636/0161-8202-43.3.313

Ferretti N, Nicoletta M, Soresi DS (2024) An integrative taxonomy approach evaluates the limits of the widespread tarantula Plesiopelma longisternale (Araneae: Mygalomorphae: Theraphosidae) and reveals a new species from Argentina. Zoologischer Anzeiger 308: 131–143. https://doi.org/10.1016/j.jcz.2023.12.003

Folmer O, Black M, Hoeh W, Lutz R, Vrijenhoek R (1994) DNA primers for amplification of mitochondrial cytochrome c oxidase subunit I from diverse metazoan invertebrates. Molecular Marine Biology and Biotechnology 3: 294–299.

Fukushima CS, Bertani R (2017) Taxonomic revision and cladistic analysis of Avicularia Lamarck, 1818 (Araneae, Theraphosidae, Aviculariinae) with description of three new aviculariine genera. ZooKeys 659: 1–185. https://doi.org/10.3897/zookeys.659.10717

Funk DJ, Omland KE (2003) Species-level paraphyly and polyphyly: Frequency, causes, and consequences, with insights from animal mitochondrial DNA. Annual Review of Ecology, Evolution, and Systematics 34(1): 397–423. https://doi.org/10.1146/annurev.ecolsys.34.011802.132421

Gallon RC (2005) Ashantia Strand, 1908 is a junior synonym of Euathlus Ausserer, 1875 (Araneae, Theraphosidae, Theraphosinae). Bulletin of the British Arachnological Society 13: 199–201.

Galtier N, Nabholz B, Glémin S, Hurst GD (2009) Mitochondrial DNA as a marker of molecular diversity: a reappraisal. Molecular Ecology 18: 4541–4550. https://doi.org/10.1111/j.1365-294x.2009.04380.x

Gandullo R, Maletti E, Faggi A (2004) Diversidad florística del Parque Provincial Copahue, Neuquén, Argentina. Boletín de la Sociedad Argentina de Botánica 39(3–4): 265–281.

Goloboff PA, Catalano SA (2016) TNT version 1.5, including a full implementation of phylogenetic morphometrics. Cladistics 32(3): 221–238. https://doi.org/10.1111/cla.12160

González Díaz EF (1972) Descripción geológica de la Hoja 30 e, Agua Escondida, provincias de Mendoza y La Pampa. Dirección Nacional de Geología y Minería, Boletín 135: 79 pp. Buenos Aires.

Hamilton CA, Hendrixson BE, Bond JE (2016) Taxonomic revision of the tarantula genus Aphonopelma Pocock, 1901 (Araneae, Mygalomorphae, Theraphosidae) within the United States. ZooKeys 560: 1–340. https://doi.org/10.3897/zookeys.560.6264

Hamilton CA, Hendrixson BE, Silvestre Bringas K (2024) Discovery of a new tarantula species from the Madrean Sky Islands and the first documented instance of syntopy between two montane endemics (Araneae, Theraphosidae, Aphonopelma): a case of prior mistaken identity. ZooKeys 1210: 61–98. https://doi.org/10.3897/zookeys.1210.125318

Hebert PD, Cywinska A, Ball SL, deWaard JR (2003) Biological identifications through DNA barcodes. Proceedings of the Royal Society of London, Series B: Biological Sciences 270(1512): 313–321.

Hoang DT, Chernomor O, von Haeseler A, Minh BQ, Vinh LS (2018) UFBoot2: improving the ultrafast bootstrap approximation. Molecular Biology and Evolution 35(2): 518–522. https://doi.org/10.1093/molbev/msx281

Horoiwa M, Mandagi IF, Sutra N, Montenegro J, Tantu FY, Masengi KWA, Nagano AJ, Kusumi J, Yasuda N, Yamahira K (2021) Mitochondrial introgression by ancient admixture between two distant lacustrine fishes in Sulawesi Island. PLoS ONE 16(6): e0245316. https://doi.org/10.1371/journal.pone.0245316

Kalyaanamoorthy S, Minh BQ, Wong TKF, von Haeseler A, Jermiin LS (2017) ModelFinder: fast model selection for accurate phylogenetic estimates. Nature Methods 14(6): 587–589. https://doi.org/10.1038/nmeth.4285

Katoh K, Misawa K, Kuma K, Miyata T (2002) MAFFT: a novel method for rapid multiple sequence alignment based on fast Fourier transform. Nucleic Acids Research 30(14): 3059–3066. https://doi.org/10.1093/nar/gkf436

Korba J, Opatova V, Calatayud-Mascarell A, Enguídanos A, Bellvert A, Adrián S, Sánchez-Vialas A, Arnedo MA (2022) Systematics and phylogeography of western Mediterranean tarantulas (Araneae: Theraphosidae). Zoological Journal of the Linnean Society 196(2): 845–884. https://doi.org/10.1093/zoolinnean/zlac042

Maddison WP, Maddison DR (2021) Mesquite: a modular system for evolutionary analysis. Version 3.7. http://www.mesquiteproject.org/

Mirande J (2009) Weighted parsimony phylogeny of the family Characidae (Teleostei: Characiformes). Cladistics 25(6): 574–613. https://doi.org/10.1111/j.1096-0031.2009.00262.x

Nguyen LT, Schmidt HA, von Haeseler A, Minh BQ (2015) IQTREE: a fast and effective stochastic algorithm for estimating maximum-likelihood phylogenies. Molecular Biology and Evolution 32(1): 268–274. https://doi.org/10.1093/molbev/msu300

Nixon KC (2004) ASADO, version 1.61 TNT-MrBayes Slaver (vl 5.30). Published by the author, Ithaca, New York.

Perafán C, Pérez-Miles F (2014) The Andean tarantulas Euathlus Ausserer, 1875, Paraphysa Simon, 1892 and Phrixotrichus Simon, 1889 (Araneae: Theraphosidae): phylogenetic analysis, genera redefinition and new species descriptions. Journal of Natural History 48(39–40): 2389–2418. https://doi.org/10.1080/00222933.2014.902142

Petrunkevitch A (1925) Arachnida from Panama. Connecticut Academy of Arts and Sciences 27: 51–248.

Prina AO, Alfonso GL, Muino WA (2003) Contribuciones al conocimiento de la flora de Malargüe. Nuevas citas para la provincia de Mendoza (Argentina). Parte I. Revista Facultad Agronomía UNLPam 14(1/2).

Rambaut A (2009) FigTree. Version 1.3.1. http://tree.bio.ed.ac.uk/software/figtree

Ríos-Tamayo D (2020) Three new species of Euathlus Ausserer, 1875 (Araneae, Theraphosidae) from Argentina. Studies on Neotropical Fauna and Environment 55(2): 83–95. https://doi.org/10.1080/01650521.2019.1696653

Ríos-Tamayo D (2024) Taxonomy and phylogeny of the genus Trichopelma Simon, 1888 (Araneae: Theraphosidae: Trichopelmatinae) in Cuba, with the descriptions of seven new species and a new species of Thalerommata Ausserer, 1875. Journal of Insect Biodiversity and Systematics 10(2): 347–399. https://doi.org/10.61186/jibs.10.2.347

Schmidt G (1996) Die Typusart von Phrixotrichus Simon, 1888 (Araneida: Theraphosidae: Theraphosinae). Arachnologisches Magazin 4(9): 14–18.

Schwerdt L, de Villalobos AE, Ferretti N, Pérez-Miles F (2021) Development, growth and allometry in a cohort of the tarantula Grammostola vachoni (Araneae: Theraphosidae). Zoologischer Anzeiger 293: 37–45. https://doi.org/10.1016/j.jcz.2021.05.005

Sérsic AN, Cosacov A, Cocucci AA, Johnson LA, Pozner R, Avila LJ, Sites JW, Morando M (2011) Emerging phylogeographic patterns in plants and terrestrial vertebrates from Patagonia. Biological Journal of the Linnean Society 103(2): 475–494. https://doi.org/10.1111/j.1095-8312.2011.01656.x

Tello NE, Villegas DC, Cavallaro SL, Nicosia Burgos FR, Frattalocchi CN, Greco MG, Lamarca ML, Fontaneto PJ, Rosas MA, Marengo HG (2021) Carta de Línea de Base Ambiental 3569-III/3572-IV Malargüe (Boletín N° 439, 170 pp.). Servicio Geológico Minero Argentino, Instituto de Geología y Recursos Minerales Buenos Aires.

Varekamp JC, Zareski JE, Camfield LM, Todd E (2016) Copahue volcano and its regional magmatic setting. In: Tassi F, Vaselli O, Caselli AT (Eds) Copahue Volcano, pp. 81–117. Springer. https://doi.org/10.1007/978-3-662-48005-2_5

Vasconcelos R, Montero‑Mendieta S, Simó‑Riudalbas M, Sindaco R, Santos X, Fasola M, Llorente G, Razzetti E, Carranza S (2016) Unexpectedly high levels of cryptic diversity uncovered by complete DNA barcoding of reptiles of the Socotra Archipelago. PLoS ONE 11: e0149985. https://doi.org/10.1371/journal.pone.0149985

Wilson JD, Bond JE, Harvey MS, Ramírez MJ, Rix MG (2023) Correlation with a limited set of behavioral niches explains the convergence of somatic morphology in mygalomorph spiders. Ecology and Evolution 13: e9706. https://doi.org/10.1002/ece3.9706

World Spider Catalog (2025) World Spider Catalog. Version 26. Natural History Museum Bern, online at http://wsc.nmbe.ch, accessed on 25 June 2025. https://doi.org/10.24436/2

Zhou Z, Guo H, Han L, Chai J, Che X, Shi F (2019) Singleton molecular species delimitation based on COI-5P barcode sequences revealed high cryptic/undescribed diversity for Chinese katydids (Orthoptera: Tettigoniidae). BMC Evolutionary Biology 19: 79. https://doi.org/10.1186/s12862-019-1404-5

Supplementary material

Supplementary material 1

Table S1

Allegue M, Peralta-Seen N, Ferretti N (2025)

Data type: .xlsx

Explanation notes: Data matrix showing the distribution of character states in cladistic analysis (? = unknown, – = non-applicable; both codifications treated as missing data).

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.

https://doi.org/10.3897/asp.83.e171040.suppl1

Download file (13.79 kb)

Abstract

Keywords

﻿1. Introduction

﻿2. Materials and Methods

﻿2.1. Morphological work

﻿2.2. Molecular work

﻿2.3. Phylogenetic analyses

﻿2.3.1. Maximum parsimony

﻿2.3.2. Maximum Likelihood

﻿2.4. Map construction

﻿2.5. Sexual behavior

﻿3. Results

﻿3.1. Maximum parsimony

﻿3.2. Maximum likelihood

﻿3.3. Taxonomy

﻿3.3.1. Genus Euathlus Ausserer, 1875

Amended diagnosis.

Species included.

﻿3.3.2. Euathlus basalticus sp. nov. Allegue and Ferretti

Type material.

Other material.

Diagnosis.

Remarks.

Description male.

Description female.

Etymology.

Distribution and natural history.

﻿3.3.3. Euathlus kupal sp. nov. Allegue and Ferretti

Type material.

Diagnosis.

Description male.

Description female.

Etymology.

Distribution and natural history.

﻿3.3.4. Euathlus susanae sp. nov. Peralta-Seen, Allegue and Ferretti

Type material.

Other material.

Diagnosis.

Description male.

Description female.

Etymology.

Distribution and natural history.

Sexual behavior.

﻿3.3.5. Euathlus tenebrarum Ferretti, 2015

Type material.

Other material.

Amended diagnosis.

Description female.

Remarks.

Distribution.

﻿4. Discussion

﻿5. Declarations

﻿6. Acknowledgments

﻿7. References

Supplementary material

1. Introduction

2. Materials and Methods

2.1. Morphological work

2.2. Molecular work

2.3. Phylogenetic analyses

2.3.1. Maximum parsimony

2.3.2. Maximum Likelihood

2.4. Map construction

2.5. Sexual behavior

3. Results

3.1. Maximum parsimony

3.2. Maximum likelihood

3.3. Taxonomy

3.3.1. Genus Euathlus Ausserer, 1875

3.3.2. Euathlus basalticus sp. nov. Allegue and Ferretti

3.3.3. Euathlus kupal sp. nov. Allegue and Ferretti

3.3.4. Euathlus susanae sp. nov. Peralta-Seen, Allegue and Ferretti

3.3.5. Euathlus tenebrarum Ferretti, 2015

4. Discussion

5. Declarations

6. Acknowledgments

7. References