Eresus transcaucasicus, Zamani & Seropian & Zarikian & Bulbulashvili & Szűts, 2025

Zamani, Alireza, Seropian, Armen, Zarikian, Noushig, Bulbulashvili, Natalia & Szűts, Tamás, 2025, Different, but still the same: integrative taxonomy confirms a new species of Eresus Walckenaer, 1805 (Araneae, Eresidae) from the South Caucasus, ZooKeys 1249, pp. 1-13 : 1-13

Eresus transcaucasicus sp. nov.

Figs 1 A – F , 2 A – D , 3 A – F , 4 A – L

Eresus kollari : Zarikian 2022: 759, fig. 1 (♂).

Eresus sp.: Seropian et al. 2023: 237, fig. S 1 (♂).

Type material.

Holotype • ♂ ( ZMUT 1017 , SAJ 366 ): Armenia: Aragatsotn Province: Ara Mountains , 40°23'N, 44°28'E, 1770 m, 03.11.2022, leg. N. Zarikian . Paratypes: • 5 ♂ ( ZMUT 1018 , HNHM 11678 , HNHM 11448 , HNHM 11589 , HNHM 11491 ), collected with the holotype ; • 2 ♂ ( ISU; CaBOL-IDs 1018700, 1018701): Georgia: Shida Qartli Region: Gori, path to Tsedisi Fortress , steppe, 41°58'02.6"N, 44°05'54.2"E, 850 m, 23.10.2021, leg. A. Seropian, N. Bulbulashvili ; • 1 ♂ ( ISU; CaBOL-ID 1009989): Gori , steppe, 41°58'31.1"N, 44°06'03.6"E, 600 m, 25.09.2024, leg. N. Bulbulashvili ; • 1 ♂ ( ISU; CaBOL-ID 1009988): Tbilisi: Dighomi village , heathland, 41°46'49.8"N, 44°42'14.0"E, 667 m, 28.09.2024, leg. A. Seropian, N. Bulbulashvili.

Diagnosis.

The new species belongs to the sandaliatus group sensu Zamani et al. (2025). In the overall shape of the conductor (Cn) and the general coloration pattern of the body and appendages, it most closely resembles E. kollari and E. hermani . It can be distinguished from E. kollari by its more robust terminal tooth (TT) having a distinct bulge (Figs 2 C, F, I, L , 3 C, F cf. Miller et al. 2012: fig. 43 J). From E. hermani , it differs in the conductor distinctly longer than wide in retrolateral view (vs. almost as long as wide; Figs 2 C, F, I, L , 3 C, F cf. Kovács et al. 2015: fig. 3 B).

Description.

Male (holotype). Habitus as in Figs 1 B , 2 D . Total length 8.21; carapace 4.68 long, 3.21 wide, 2.50 high; abdomen 4.78 long, 3.76 wide. Carapace and chelicerae dark brown, almost black, densely coated with black setae; pars cephalica elevated, covered with black setae; pars thoracica with sparse white setae, margins with few orange setae. Palpal segments without white setae; femur, patella and tibia densely covered with dark setae of black or grey tone. Legs I and II densely coated with black setae, with rings of white setae on proximal and distal joints of segments; legs III and IV coated with red setae coverage; distal end of tibiae and metatarsi with white ring of setae. Abdomen black on sides, anterior part of dorsum and posterior to epigastric fold; dorsum red, with two pairs of large and one pair of small black dots; venter anterior to epigastric fold red; booklung covers with short red setae. Measurements of leg segments: I: 9.02 (2.89, 1.45, 1.51, 1.86, 1.31); II: 7.75 (2.45, 1.37, 1.31, 1.53, 1.09); III: 6.60 (2.19, 1.23, 1.06, 1.30, 0.82); IV: 9.09 (2.82, 1.62, 1.85, 1.72, 1.08).

Palp as in Fig. 2 A – C ; conductor (Cn) distinctly longer than wide; terminal tooth (TT) well-developed and robust, slightly bulging, subequal to lamella (Lm), with smooth transition to base of conductor in lateral view; lamella> 2 × longer than high; lamellar groove shallow.

Variation (n = 5). Habitus of paratypes from Armenia as in Fig. 1 A, C , and from Georgia as in Fig. 1 D – F . Measurements: total length 8.21–8.92; carapace length 4.68–4.72, width 3.21–3.35. Sparse white setae may be present at black spots around sigilla (Fig. 1 D – F ). Palp of paratypes from Armenia as in Fig. 3 A, B , and from Georgia as in Figs 3 C – F , 4 A – L . Conductor: length / width ratio: 1.2–1.5; very slight shoulder present in some specimens (Figs 2 C , 4 C, F ); depth of lamellar groove slightly varying (Figs 3 A – F , 4 C, F, I, L ).

Female. Unknown.

Habitat.

The specimens were collected under stones and on the ground in warm, dry mountain slopes with sparse vegetation.

Phenology.

Early to late autumn.

Distribution.

Known only from the listed localities in Lesser Caucasus Mountains in Armenia and Georgia (Fig. 5 ).

Etymology.

The specific epithet refers to the distribution of the species in the South Caucasus, also known as Transcaucasia.

Figures

Figure 1. Habitus of the male holotype (B. ZMUT 1017, from Armenia) and paratypes (A, C. HNHM 11678 and ZMUT 1018, from Armenia; D – F. ISU - CaBOL 1009989, 1009988, 1018701, from Georgia) of Eresus transcaucasicus sp. nov., dorsal view. Scale bars: 4 mm.

Figure 2. Palp (A – C) and habitus (D) of the male holotype (ZMUT 1017, from Armenia) of Eresus transcaucasicus sp. nov. A. Prolateral view; B. Ventral view; C. Retrolateral view; D. Lateral view. Abbreviations: Cn – conductor, Lm – lamella, TT – terminal tooth. Scale bars: 0.4 mm (A – C), 4 mm (D).

Figure 3. Palps of the male paratypes of Eresus transcaucasicus sp. nov., retrolateral view. A, B. HNHM 11448 and HNHM 11678, respectively, from Armenia; C – F. ISU - CaBOL 1009988, 1009989, 1018701, 1018700, respectively, from Georgia. Scale bars: 0.4 mm.

Figure 4. Palps of the male paratypes (A – C. ISU - CaBOL 1009988; D – F. ISU - CaBOL 1009989; G – I. ISU - CaBOL 1018700; J – L. ISU - CaBOL 1018701) of Eresus transcaucasicus sp. nov. from Georgia. A – C. Tibia, cymbium and bulb, prolateral, ventral and retrolateral views; D, G, J. Embolic division, prolateral view; E, H, K. Same, ventral view; F, I, L. Same, retrolateral view. Scale bars: 0.4 mm (A – C), 0.1 mm (D – L).

Figure 5. Phylogenetic and species delimitation results, based on the COI dataset: the maximum likelihood phylogram, along with the results of various species delimitation methods. Taxon names in bold represent the new species described here. Morphology-based species concepts are indicated by their respective Latin names. Each horizontal bar represents a putative species as inferred by a molecular method. The preferred delimitation results are highlighted in color, others are in grayscale. Different colors correspond to recognized species groups as explained in Zamani et al. (2025).