Solenysa bilamellata 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 bilamellata Ballarin & Eguchi sp. nov.

Figs 3 A-J , 4 G-I

Material examined.

Holotype ♂ Japan: Kyushu Is., • Ōita Pref.: Saiki City, Kitachi, Ono , 54 m, 32.92845°N, 131.94978°E, humid leaf litter in a mixed forest, 25. Mar. 2019, F. Ballarin leg. ( NSMT -Ar 26191 ) . Paratypes. Japan: • Kyushu Is., Saga Pref.: 1 ♀, Saga City, Kinryumachi Kinryu, Kotohira Shrine (金刀比羅神社), 33.330°N, 130.299°E, 31. Jul. 2005, A. Akihisa leg. ( NSMT -Ar 26192 ) • Ōita Pref.: 1 ♂, 1 ♀, Saiki City, Kamae Oaza Kamaeura , 159 m, 32.81950°N, 131.91222°E, leaf litter in a deciduous broadleaf forest on a steep hill, 21. Mar. 2019, F. Ballarin leg. ( MNHAH) • 2 ♀, Kitachi, Ono , 54 m, 32.92845°N, 131.94978°E, humid leaf litter in a mixed forest, 25. Mar. 2019, F. Ballarin leg. ( NSMT -Ar 26193 ) • 2 ♀, Kunisaki Peninsula, Kunisaki City, Akimachi Yagawa , 203 m, 33.49561°N, 131.60430°E, leaf litter in a broadleaf forest on a slope, 02. Aug. 2022, sifter, F. Ballarin leg. ( TKPM -AR 3246 ) .

Diagnosis.

Species closely related to other Solenysa species from western Japan. Males of S. bilamellata sp. nov. can be easily distinguished from males of S. reflexilis , S. macrodonta , and S. trunciformis by the presence of two large, lamellar-like protrusions of the median tegular apophysis (AP and MP) and having a rounded tip, both clearly visible when the palp is observed laterally (vs only AM visible and MP missing or reduced in S. reflexilis ; or AM reduced and only MP clearly visible but with a pointed or truncated tip in the other three species). Additionally, S. bilamellata sp. nov. can be distinguished by the straight second branch of the lamella (LA 2) (vs LA 2 curved in S. reflexilis and S. macrodonta ); by the smaller LA 1 (LA 1 longer in S. reflexilis ); the sharper tip of the upper branch of LA 3 (vs tip of LA 3 wide and fringed in S. macrodonta ), and by the shape of the lamellar-like anterior terminal hypophysis (ATA) (vs ATA with a different shape, wider in S. reflexilis or thinner in S. macrodonta , and S. trunciformis ) (cf. Fig. 3 A-D vs Figs 4 G-I , 6 A-D , 7 A-D , 8 A-D , 11 A-F ). Females of S. bilamellata sp. nov. can be distinguished from females of S. reflexilis , S. macrodonta , and S. trunciformis by the different shape of the epigyne, having a more transversely ovate ventral plate (VP) with short and pointed lateral borders headed internally and a dorsal plate (DP) with more rounded lobes (vs VP more trapezoidal with lateral borders headed externally and DP with more trapezoidal lobes in S. reflexilis ; or VP more elongated posteriorly with longer lateral borders and DP with oval lobes in S. macrodonta and S. trunciformis ) (cf. Fig. 3 G-J vs Figs 6 G-J , 7 G-J , 8 G-J ).

Description.

Male (holotype). Total length: 1.22. Prosoma 0.67 long; 0.48 wide. Clypeus 0.24 long. Habitus as in Fig. 3 E . Cephalic area distinctly elevated. Carapace oval with conspicuous lateral lobes. Carapace, chelicera, mouth parts, and sternum uniformly brick-red. Chelicera with four promarginal and three retromarginal teeth. Legs uniformly red-yellowish. Length of legs as follows: I (0.64, 0.15, 0.63, 0.52, 0.42), II (0.60, 0.14, 0.55, 0.44, 0.40), III (0.47, 0.14, 0.38, 0.36, 0.33), IV (0.55, 0.13, 0.51, 0.44, 0.37). TmI = 0.54, Opisthosoma uniformly greyish with scattered small white marks on dorsal side, dorsal-posterior tip of opisthosoma lighter gray in some individuals.

Palp as in Figs 3 A-D , 4 G-I . Palpal tibia elongated, ~ 2 × longer than patella, bearing four long, thin setae on anterior-retrolateral side; proximal tibial apophysis (PTP) well-developed, strongly protruding dorsally, bearing four – five long, thin setae. Cymbium with well-developed probasal cymbial apophysis (PBP), hook-like when observed laterally or dorsally, bent retrolaterally, with massive basal part, ending with thin, rounded tip. Cymbial retrolateral process (CRP) thorn-like. Paracymbium (P) U-shaped, elongated antero-posteriorly, ventral lobe (VLP) protruding anteriorly. Solenysa tegular triangle (STT) thick. Lamella with three well-developed branches: anterior branch (LA 1) short and stocky; median branch (LA 2) straight, strongly sclerotized, needle-like; posterior branch (LA 3) with long, ribbon-like basal part, distal part forked into two needle-like branches headed antero-dorsally, ventral branch sclerotized, dorsal branch transparent ending blunt. Radix (R) strongly sclerotized. Distal suprategular apophysis (DSA) well-developed, strongly sclerotized. Median terminal apophysis (MTA) bearing two well-visible, sclerotized, lamellar protrusions protruding antero-ventrally: anterior protrusion (AP) lobated, longer than wide; median protrusion (MP) also longer than wide and lobated but slightly thinner and sharper than AP, ending with a rounded, serrated tip. Anterior terminal apophysis (ATA) stocky, lobated, lacking any median tooths. Embolus (E) sclerotized, ribbon-like, twisted, ending with a sharp tip.

Female (one of the paratypes). Total length: 1.25. Prosoma 0.63 long; 0.45 wide. Clypeus 0.21 long. Habitus as in Fig. 3 F . Length of legs as follows: I (0.61, 0.14, 0.60, 0.47, 0.40), II (0.56, 0.14, 0.50, 0.43, 0.38), III (0.44, 0.14, 0.35, 0.29), IV (0.58, 0.14, 0.48, 0.42, 0.37). Color and other features as in male.

Epigyne and vulva as in Fig. 3 G-J , protruding, ventral side flattened when observed laterally. Solenoid (SL) with numerous small coils give a wrinkled texture, lacking clear, wide folds. Ventral plate (VP) transversely ovate, with pointed lateral borders headed posteriorly; anterior border strongly concave, posterior border rounded. Dorsal plate (DP) divided into two rounded lobes separated from each other by ~ 1 / 3 of their width. Copulatory ducts (CD) headed anteriorly then posteriorly before reaching spermathecae. Fertilization ducts (FD) thin, bent anteriorly. Spermathecae (S) wide, kidney-shaped (Fig. 3 J ).

Etymology.

The species name is derived from the Latin prefix bi - meaning “ two, ” and lamellata meaning “ bearing lamellae. ” It refers to the two flat, lamellar protrusions (AP and MP) of the median terminal apophysis that are diagnostic for this species. Adjective.

Distribution.

Endemic to northern and eastern Kyushu, Western Japan (Fig. 13 ). See also remarks of S. reflexilis .

Habitat.

Humid leaf litter on the floor of broadleaved forests.

Figures

Figure 3. Solenysa bilamellata 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: AP anterior protrusion of MTA; CD copulatory duct; DP dorsal plate; DSA distal suprategular apophysis; E embolus; EC epigynal collar; FD fertilization duct; LA 3 posterior branch of lamella; MTA median terminal apophysis; P paracymbium; PBP probasal cymbial apophysis; PP posterior protrusion of MTA; PTP proximal tibial apophysis; 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 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 6. Solenysa reflexilis from Yakushima 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. Scale bars: 0.05 mm (A – D, G – J); 0.5 mm (E, F).

Figure 7. Solenysa macrodonta from Hiroshima 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. Scale bars: 0.05 mm (A – D, G – J); 0.5 mm (E, F).

Figure 8. Solenysa trunciformis A male palp, prolateral, sample from Okayama B ditto, retrolateral C ditto, dorsal D ditto, ventral E habitus of male, dorsal F habitus of female, dorsal G epigyne, posterior, sample from Tokushima H ditto, ventral I ditto, lateral J vulva, dorsal. Scale bars: 0.05 mm (A – D, G – J); 0.5 mm (E, F).

Figure 11. Embolic divisions of Solenysa species A S. reflexilis from Yakushima, ventral B ditto, retrolateral C S. macrodonta from Hiroshima, ventral D ditto, retrolateral E S. trunciformis from Okayama, ventral F ditto, retrolateral G S. longqiensis, ventral H ditto, retrolateral I S. yangmingshana J ditto, retrolateral. (N. B., in A-D embolus is broken). Abbreviations: AP anterior protrusion of MTA; ATA anterior terminal apophysis; E embolus; LA 1 anterior branch of lamella; LA 2 median branch of lamella; LA 3 posterior branch of lamella; MP median protrusion of MTA; MT median tooth on anterior terminal apophysis; MTA median terminal apophysis; PP posterior protrusion of MTA; PTA posterior terminal apophysis; R radix. Scale bars: 0.05 mm.

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.