Solenysa shimatchu Ballarin & Eguchi, 2025

Ballarin, Francesco, Liao, Hauchuan, Touyama, Zento & Eguchi, Katsuyuki, 2025, Review of the spider genus Solenysa Simon, 1894 in Western Japan and Central Ryukyu with the description of three new species (Araneae, Linyphiidae), ZooKeys 1232, pp. 97-130 : 97-130

Solenysa shimatchu Ballarin & Eguchi sp. nov.

Figs 1 A – J , 4 A-C , 5 A, B

Material examined.

Holotype ♂ Japan: • Kagoshima Pref., Amami-Ōshima Is., Setouchi, Amurogama , 121 m, 28.22261°N, 129.31695°E, humid forest litter in a flat area near a creek, 10. Jul. 2021, F. Ballarin leg. ( NSMT -Ar 26184 ) . Paratypes. Japan: Kagoshima Pref., Amami-Ōshima Is., • 3 ♀, Amami, Naze Oaza Asato , 176 m, 28.33066°N, 129.48115°E, forest litter, 8. Jul. 2021, F. Ballarin leg. ( NSMT -Ar 26185 ) • 1 ♀, Sumiyocho Oaza Kawauchi , 54 m, 28.31219°N, 129.42390°E, forest litter on a steep cliff, 8. Jul. 2021, F. Ballarin leg. ( NSMT -Ar 26186 ) • 1 ♂, Yamato, Ongachi , ~ 28.33111°N, 129.39436°E, 9. Mar. 2014, T. Suguro leg. ( TKPM -AR 3243 ) • 1 ♂, 3 ♀, Yamato, Tsunagu , 196 m, 28.33224°N, 129.41763°E, humid forest litter with stones near a creek, 9. Jul. 2021, F. Ballarin leg. ( MSNVR -Ar 032 –035) • 2 ♀, Naze, Oaza Chinase , 63 m, 28.34896°N, 129.44969°E, broadleaf forest litter, 9. Jul. 2021, F. Ballarin leg. ( TKPM -AR 3244 ) • 1 ♂, 5 ♀, Setouchi, Amurogama , 121 m, 28.22261°N, 129.31695°E, humid forest litter in a flat area near a creek, 10. Jul. 2021, F. Ballarin leg. ( MNHAH) • 1 ♂, 1 ♀, Tatsugo, Akina , 245 m, 28.42290°N, 129.54688°E, rather dry forest litter, F. Ballarin leg. ( FBPC) • 2 ♀, Uken, Ashiken , 208 m, 28.30780°N, 129.27311°E, rather dry litter on a steep slope near a creek, 12. Jul. 2021, F. Ballarin leg. ( NSMT -Ar 26187 ) .

Other material examined.

Japan: Kagoshima Pref., Amami-Ōshima Is., • 1 ♀, Naze, Oaza Chinase , same locality and date, 274 m, 28.35705°N, 129.45436°E, broadleaf forest litter, 9. Jul. 2021, F. Ballarin leg. ( FBPC) • 1 ♀, Tatsugo, Akina , 64 m, 28.42192°N, 129.55104°E, humid forest litter with stones, 11. Jul. 2021, F. Ballarin leg. ( FBPC) • Tokunoshima Is., 1 ♂, 1 ♀, Amagi-cho, Nishiagina , ~ 27.7639°N, 128.9398°E, 28. Mar. 2018, T. Suguro leg. ( NSMT)

Diagnosis.

Species closely related to S. yambaruensis sp. nov. from which it can be easily separated by the dorsal color pattern of the opisthosoma, having a single white mark on the dorsal-posterior tip of the opisthosoma (vs three marks) (cf. Fig. 1 A-E, F vs Fig. 2 E, F ). Males of S. shimatchu sp. nov. can be easily separated from males of S. yambaruensis sp. nov. by the different shape of the posterior branch of the lamella (LA 3), thinner and ending with a long and straight single needle-like tip (vs LA 3 wider, ribbon-like, and ending with a bent spine and two denticles) (cf. Fig. 4 A-C vs Fig. 4 D-F ). Additionally, the paracymbium (P) has a less-developed and shorter ventral lobe (VLP), headed ventrally (vs VLP with a wider lobe headed antero-ventrally); the probasal cymbial apophysis (PBP) is less bent and headed retrolaterally when observed dorsally (vs PBP more bent and headed antero-retrolaterally); and the proximal tibial apophysis (PTP) is more developed and with thicker spines (vs PTP less developed and with thinner spines) (cf. Fig. 1 A-D vs Figs 2 A-D , 5 A, B, C – F ).

Females of S. shimatchu sp. nov. can be distinguished from females of S. yambaruensis sp. nov. by the different shape of the epigyne: more rounded and protruding when observed laterally (vs flatter and less protruding); having a more V-shaped ventral plate (VP) (vs VP more trapezoidal with flatter posterior borders); and a more protruding lobe of the dorsal plate (LDP) (vs LDP less protruding) (cf. Fig. 1 G-J vs Fig. 2 G-J ).

For additional separation from other Solenysa spp. see the species group’s diagnosis.

Description.

Male (holotype). Total length: 1.21. Prosoma 0.71 long; 0.46 wide. Clypeus 0.24 long. Habitus as in Fig. 1 E . Length of legs as follows: I 2.38 (0.62, 0.15, 0.63, 0.53, 0.45), II 2.02 (0.56, 0.14, 0.51, 0.43, 0.38), III 1.61 (0.43, 0.13, 0.37, 0.36, 0.33), IV 1.80 (0.50, 0.13, 0.44, 0.39, 0.34). Opisthosoma uniformly greyish with scattered small lighter dots, one wider, distinct dorsal whitish mark near posterior tip of opisthosoma. Other somatic characters as reported in species group.

Palp as in Figs 1 A-D , 4 A-C , 5 A, B . Proximal tibial apophysis (PTP) strongly protruding antero-retrolaterally, bearing 3 thick spines. Probasal cymbial apophysis (PBP), massive, hook-like when observed dorsally, headed retrolaterally. Ventral lobe of paracymbium (VLP) headed ventrally. Lamella with 3 well-developed branches: LA 1 wide, ribbon-like, transparent; LA 2 and LA 3 both sclerotized, strait, needle-like; LA 2 shorter, headed antero-ventrally; LA 3 longer, with a slightly wider, ribbon-like basal part, ending sharp and thin, headed antero-dorsally. Posterior terminal apophysis (PTA), thin and transparent, almost invisible. Median terminal apophysis (MTA) half-transparent, lobated, slightly twisted. Anterior terminal apophysis (ATA) ribbon-like, strongly sclerotized, flattened, slightly twisted, headed anteriorly, ending with a sharp tip. Median tooth (MT) of ATA small and stocky, headed anteriorly. Embolus (E) transparent, twisted, and fringed, partially hidden by ATA.

Female (one of the paratypes). Total length: 1.26. Prosoma 0.72 long; 0.46 wide. Clypeus 0.24 long. Habitus as in Fig. 1 F . Length of legs as follows: I 2.22 (0.58, 0.16, 0.57, 0.50, 0.41), II 1.93 (0.53, 0.13, 0.47, 0.43, 0.37), III 1.61 (0.43, 0.14, 0.35, 0.36, 0.33), IV 1.95 (0.53, 0.14, 0.48, 0.43, 0.37). Color and other features as in male.

Epigyne and vulva as in Fig. 1 G-J , strongly protruding when observed laterally. Solenoid (SL) folded anterodorsally with 2 wide transversal folds before reaching the dorsal base of epigyne. Ventral plate (VP) slightly V-shaped, anterior border strongly concave. Dorsal plate (DP) undivided, bearing a well-developed rectangular ventral lobe (LDP) protruding posteriorly. Copulatory ducts (CD) thick, heading antero-laterally then posteriorly before reaching posterior side of spermathecae. Fertilization ducts (FD) thin, Z-shaped, bent anteriorly. Spermathecae (S) wide, oval (Fig. 1 J ).

Etymology.

The specific name is derived from the word “ shimatchu ” (島っちゅ) meaning “islander” in the Amami-Ōshima local language. The name refers to the insular origin of the species endemic to Amami-Ōshima and Tokunoshima islands. Name in apposition.

Distribution.

Endemic to Amami-Ōshima and Tokunoshima islands, Central Ryukyus, Japan (Fig. 13 ).

Habitat.

This species has been observed building simple sheet webs in open spaces in humid leaf litter on the floor of broadleaved forest.

Figures

Figure 1. Solenysa shimatchu sp. nov. A male palp, prolateral B ditto, retrolateral C ditto, dorsal D ditto, ventral E habitus of male, dorsal F habitus of female, dorsal G epigyne, posterior H ditto, ventral I ditto, lateral J vulva, dorsal. Abbreviations: DP dorsal plate; DSA distal suprategular apophysis; E embolus; EC epigynal collar; LA 2 median branch of lamella; LA 3 posterior branch of lamella; LDP lobe of the dorsal plate; P paracymbium; PBP probasal cymbial apophysis; PTP proximal tibial apophysis; RLP cymbial retrolateral process; S spermatheca; SL solenoid; STT Solenysa tegular triangle; T tegulum; VLP ventral lobe of P; VP ventral plate. Scale bars: 0.05 mm (A – D, G – J); 0.5 mm (E, F).

Figure 2. Solenysa yambaruensis sp. nov. A male palp, prolateral B ditto, retrolateral C ditto, dorsal D ditto, ventral E habitus of male, dorsal F habitus of female, dorsal G epigyne, posterior H ditto, ventral I ditto, lateral J vulva, dorsal. Abbreviations: CD copulatory duct; DP dorsal plate; DSA distal suprategular apophysis; E embolus; EC epigynal collar; FD fertilization duct; LA 3 posterior branch of lamella; LDP lobe of the dorsal plate; MTA median terminal apophysis; P paracymbium; PBP probasal cymbial apophysis; PTP proximal tibial apophysis; S spermatheca; SL solenoid; STT Solenysа tegular triangle; T tegulum; VLP ventral lobe of P; VP ventral plate. Scale bars: 0.05 mm (A – D, G – J); 0.5 mm (E, F).

Figure 4. Embolic divisions of newly described Solenysa spp. A embolic division of S. shimatchu sp. nov., ventral B ditto, retrolateral C ditto, ventro-prolateral D embolic division of S. yambaruensis sp. nov., ventral E ditto, retrolateral F ditto, ventro-prolateral G embolic division of Solenysa bilamellata sp. nov., ventral H ditto, retrolateral I ditto, ventro-prolateral. Abbreviations: AP anterior protrusion of MTA; ATA anterior terminal apophysis; DSA distal supra-tegular apophysis; E embolus; LA 1 anterior branch of lamella; LA 2 median branch of lamella; LA 3 posterior branch of lamella; MT median tooth on anterior terminal apophysis; MP median protrusion of MTA; MTA median terminal apophysis; PTA posterior terminal apophysis; R radix. Scale bars: 0.05 mm.

Figure 5. Palp and embolic division of Solenysa spp. under SEM microscope A palp of S. shimatchu sp. nov., ventro-retrolateral B ditto, embolic division, ventral C palp of S. yambaruensis sp. nov., ventro-retrolateral D ditto, ventral E ditto, embolic division, ventro-prolateral F ditto, ventral. Abbreviations: ATA anterior terminal apophysis; DSA distal supra-tegular apophysis; E embolus; LA 1 anterior branch of lamella; LA 2 median branch of lamella; LA 3 posterior branch of lamella; MT median tooth on anterior terminal apophysis; MTA median terminal apophysis; P paracymbium; PTA posterior terminal apophysis; R radix; RLP cymbial retrolateral process; STT Solenysa tegular triangle; T tegulum.

Figure 13. Distribution of Solenysa species in the Ryukyu Archipelago and surrounding areas. The Ryukyu Archipelago is marked with a dashed line. Diamonds refer to records of Solenysa spp. from the literature (Shinkai et al. 2024; WSC 2024), dots refer to new records, squares indicate the species type locality, and question marks indicate uncertain records of S. reflexilis.