Longileptoneta yamasakii Ballarin & Eguchi 2022, sp. nov.
Creators: name: Ballarin, Francesco
name: Eguchi, Katsuyuki
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Leptonetidae
Longileptoneta
Longileptoneta yamasakii

description: Longileptoneta yamasakii sp. nov.
(Japanese name: yamasakinagamashiragumo ヤマサキナガマシラグモ)
Figs. 1A–G, 2A–F, 3A–D
DNA barcode. GenBank accession number: OP680015.
Material examined. ♂ Holotype. JAPAN: Okinawa Pref.: Yonaguni-jima Is., Yaeyama-gun, Yonaguni-cho, unnamed short cave inside a deep, shadowed sinkhole, 24.45872°N, 122.95618°E, 23 m a.s.l., under stones and in mud crevices at the entrance of the cave, 02 March 2021, F. Ballarin & K. Eguchi leg. (NSMT-Ar 22244).
Paratypes. JAPAN — same data as the holotype 1♂, 19♀ (5♀ NSMT-Ar 22245; 1♂, 9♀ MNHAH-B6-000402; 5♀ RMUF); same locality, 10♀ (6♀ FBPC; 4♀ MSNVR-Ar028–031), 05 March 2021, all F. Ballarin & K. Eguchi leg.
Etymology. The new species is a patronym in honor to our colleague and friend Takeshi Yamasaki (Museum of Nature and Human Activities, Hyogo Prefecture, Japan), for his contribution to the study of arachnology and for kindly helping with field collections in Japanese caves.
Diagnosis. The male of Longileptoneta yamasakii sp. nov. can be distinguished from the male of the similar L. gutan Wang & Li, 2020 and L. shenxian Wang & Li, 2020 or any other congeners by the following combination of unique characters: presence of a pair of lanceolate apophyses (PA) on the retrodistal part of the patella (reduced to normal, sharp spines in L. gutan and L. shenxian; cf. Figs. 1B, D, 3B vs. figs. 8D and 12C in Wang et al. 2020) and a robust and strongly sclerotized prolateral sclerite (PS) (thinner PS in L. gutan and L. shenxian, or transparent and less sclerotized in other congeners (cf. Figs. 1A, G, 3A vs. figs. 8C and 12C in Wang et al. 2020). In addition, the new species can be recognized by the general shape of the other palpal sclerites when the bulb is observed ventrally or dorsally (differently shaped in L. gutan, L. shenxian and in other congeners; cf. Figs. 1G, 3C vs. figs. 8B and 12B in Wang et al. 2020). The female of L. yamasakii sp. nov. is distinguished from the female of L. gutan, L. shenxian and other congeneric species by the shape of internal genitalia having less twisted ducts (SS) and spermathecae (S) headed toward to each other (vs. more coiled SS and S headed more frontally in L. gutan and L. shenxian or usually smaller S in other congeners; cf. Figs. 2A, B, 3D vs. figs. 9C and 13C in Wang et al. 2020). The dorsal pattern, having clear dark stripes on the opisthosoma, and the general shape of genitalia both help to quickly distinguish L. yamasakii sp. nov. from any other leptonetid species living in the Ryukyus.
Description. Male (holotype). Habitus as in Fig. 2C. Total length: 2.52; prosoma 1.03 long, 0.93 wide. Carapace dark brown with a lighter central area less visible in alive specimens (Fig. 2F). Median groove, cervical grooves and radial furrows distinct. Cephalic area poorly defined, slightly raised from carapace. Six eyes all well-developed. ALE = 0.06, PLE = 0.05, PME = 0.05, ALE-PLE = 0, PLE-PME = 0.02. Chelicera, labium and maxillae uniformly brownish. Promargin of chelicera bearing a row of 8 denticles; denticles absent on retromargin. Sternum uniformly dark brown. Legs uniformly brown. Leg formula: I, IV, II, III. Leg measurements (leg II partially missing): I = 9.43 (2.57, 0.36, 2.98, 2.47, 1.05), II =? (1.83, 0.34, -), III = 5.8 (1.60, 0.25, 1.61, 1.46, 0.88), IV = 7.84 (2.11, 0.34, 2.38, 2.02, 0.99). Opisthosoma greyish with two rows of 4–5 dark transversal stripes gradually merging to each other toward the posterior part of opisthosoma. Palp as in Figs. 1A–G, 3A–C. Femur with a row of long and robust spines on ventral margin, additional strong spines on the prolateral and dorsal margins. Patella elongated, bearing a pair of robust, lanceolate apophyses (PA) on retrodistal margin. Tibia short, approx. half of length of patella, with a tubular, robust apophysis on retrodistal margin with a spine on its apex and another spine at its base (TA) (Figs. 1B, 3B). Cymbium with medial depression and several long and robust dorsal spines headed prolaterally. Bulb with three sclerites: prolateral sclerite (PS) spine-like, robust and heavily sclerotized; median sclerite (MS) long and laminar, twisted apically; retrolateral sclerite (RS) flat and wrinkled, sclerotized at its basal trait and wrapped around embolus. Embolus (E) sclerotized at its base, distally leaf-like and transparent, ending with a long, narrow lobe (Figs. 1C–G and 3A–C).
Female (based on one of the paratypes). Habitus as in Figs.2 D–F. Total length: 2.70, Prosoma 1.01 long, 0.91 wide. Similar to male for coloration and pattern. Frontal view of cephalic area as in Fig. 2E. ALE = 0.06, PLE = 0.05, PME = 0.05, ALE-PLE = 0, PLE-PME = 0.02. Leg formula: I, IV, II, III. Leg measurements: I = 5.62(1.47, 0.23, 1.71, 1.38, 0.83), II = 4.12 (1.16, 0.23, 1.17, 0.95, 0.61), III = 3.47 (0.96, 0.20, 0.92, 0.83, 0.56), IV = 4.78 (1.30, 0.22, 1.45, 1.16, 0.65). Opisthosoma wrinkled in the frontal part (Fig. 2E). Other characters as in male. Internal genitalia as in Fig. 2A, B, 3C. Atrium (AT) wide, triangular; spermathecae stalk (SS) reaching spermathecae (S) with a slight S-shaped course. Spermathecae oval, separated from each other by two and 2/3 of their diameter, slightly headed toward each other and slightly bent posteriorly toward AT.
Size variation: Male (based on 2 specimens): total length: 2.52–2.61, Prosoma 1.03–1.06 long, 0.92—0.96 wide. Female (based on 5 specimens): total length: 2.51–2.70, Prosoma 0.91–1.01 long, 0.89–0.91 wide.
Distribution. Known only from the type locality (Fig. 10).
Habitat. Cave-like habitats. The new species was found spinning small sheet-webs in mud and rock crevices on the ground and under dead wood at the entrance of a short cave opening at the bottom of a humid, shadowed sinkhole covered with subtropical vegetation (Fig. 2G).
Remarks. Longileptoneta yamasakii sp. nov. is locally abundant. The population numbered tens of specimens, often spinning webs in crevices close to each other, but occurring only in a small area of few square meters near the entrance of the short cave in the type locality. The species clearly shows troglophilic preferences, however it retains a full pigmentation and large, functional eyes. Thus, it lacks any troglomorphic characters typical of species deeply adapted to a subterranean life-style like in others leptonetids living in Ryukyus caves (e.g., M. longipalpis). This suggests that L. yamasakii sp. nov. might also inhabit screes or external habitats, especially if stable and moist. However, despite intensive collections by the authors in the surroundings of the type locality, in the leaf litter of forests covering the central area of Yonaguni-jima Is., no specimens of this or any other leptonetid species were collected.
description: Published as part of Ballarin, Francesco & Eguchi, Katsuyuki, 2022, Taxonomic notes on leptonetid spiders from the Ryukyu Archipelago with the description of two new species and the first record of the genus Longileptoneta from Japan (Araneae: Leptonetidae), pp. 371-387 in Zootaxa 5213 (4) on pages 373-377, DOI: 10.11646/zootaxa.5213.4.3, http://zenodo.org/record/7381394