Solenysa Simon, 1894

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

Genus Solenysa Simon, 1894

Type species.

Solenysa mellotteei Simon, 1894 ; type locality: Japan.

Distribution.

East Asia: Eastern mainland China, Taiwan, Korea, Japan (mainland and Ryukyus, absent in Hokkaido).

Solenysa yambaruensis group sensu Ballarin & Eguchi

Composition. Two species, S. yambaruensis sp. nov.; S. shimatchu sp. nov.

Diagnosis. Males of the S. yambaruensis group can be separated from males of other species groups by the following combination of characters: a well-developed, protruding proximal tibial apophysis (PTP) bearing three robust spines (vs PTP reduced or bearing thinner setae); a cymbium with a massive probasal cymbial apophysis (PBP) strongly bent and concave to form a wide pocket, lacking any clear spurs (vs PBP less developed, or with a different shape, or bearing some spurs); a paracymbium (P) elongated dorsal-ventrally with a well-developed ventral lobe (vs P differently shaped, elongated antero-posteriorly or with a reduced ventral lobe); a protruding, lobated median terminal apophysis (MTA) longer than wide and lacking any clear protrusions (vs MTA wider than long, or with a different shape and having some protrusions); a lamella with three, uniquely shaped branches (LA 1 -3) all well-developed: LA 1 ribbon-like and transparent, LA 2 strongly sclerotized, needle-like, LA 3 with a wide, ribbon-like basal part and ending with a sclerotized, needle-like tip (vs LA 1 -3 less sclerotized, or with a different shape).

Females of the S. yambaruensis group can be distinguished from females of other species groups by the following combination of characters: solenoid (SL) with a smooth surface folded into two transversal coils (vs SL differently shaped, with a wrinkled surface, lacking two clear wide folds); a dorsal plate (DP) with a short, undivided rectangular lobe (LDP) protruding posteriorly (vs LDP lacking, divided into two lobes, or differently shaped).

Description. Cephalic area distinctly elevated in both sexes. 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. TmI = 0.54, TmIV absent. Leg Tibial spine formula = 1-1 - 1 - 1. Opisthosoma uniformly greyish with one or three white marks on dorsal side, one mark always on dorsal-posterior tip of opisthosoma. Other somatic features as in other Solenysa spp.

Palpal tibia elongated, ~ 2 × longer than patella, bearing three long, thin setae on anterior-retrolateral side; proximal tibial apophysis (PTP) well-developed, bearing three robust spines. Cymbium with well-developed probasal cymbial apophysis (PBP), massive, folded to form a wide pocket strongly bent retrolaterally, hook-like when observed dorsally. Cymbial retrolateral process (CRP) thorn-like. Paracymbium (P) U-shaped, elongated dorsal-ventrally, ventral lobe (VLP) wide. Solenysa tegular triangle (STT) long and narrow. Lamella with three well-developed branches: anterior branch (LA 1) ribbon-like, transparent; median branch (LA 2) straight, strongly sclerotized, needle-like; posterior branch (LA 3) with a more or less wide, ribbon-like basal part, ending with a sharp, sclerotized point, straight or bent anteriorly. Radix (R) strongly sclerotized. Distal suprategular apophysis (DSA) well-developed, strongly sclerotized. Median terminal apophysis (MTA) lobated, ~ 2 × longer than wide, protruding antero-ventrally. Anterior terminal apophysis (ATA) ribbon-like, flattened, slightly twisted, and bent ventrally, ending with a more or less sharp tip, bearing a short median tooth (MT). Embolus (E) transparent, ribbon-like, and fringed.

Epigyne more or less protruding when observed laterally, Solenoid (S) with smooth surface lacking wrinkles, connected to the dorsal base of epigyne, folded anterodorsally with approximately two folds. Ventral plate (VP) V-shaped or trapezoidal; anterior border strongly concave, posterior border flat or slightly V-shaped. Dorsal plate (DP) undivided, bearing a more or less protruding lobe (LDP). Copulatory ducts (CD) thick, heading anteriorly then posteriorly before reaching spermathecae. Fertilization ducts (FD) thin, slightly twisted, bent anteriorly. Spermathecae (S) wide, oval.

Distribution. Ryukyu Archipelago

Remarks. The Solenysa species were grouped by Tu and Hormiga (2011) into four species groups based on the morphology of their genitalia: the Solenysa longqiensis group ( S. longqiensis , S. yangmingshana , and S. spiralis (?) from Mainland China and Taiwan), the S. wulingensis group ( S. geumoensis , S. retractilis , S. wulingensis , and S. tianmushana from Mainland China and Korea), the S. protrudens group ( S. protrudens and S. lanyuensis from Mainland China and Taiwan), and the S. mellotteei group ( S. macrodonta , S. mellotteei , S. ogatai , S. partibilis , S. reflexilis , and S. trunciformis , all from Japan) ( Tu and Hormiga 2011; Tian and Tu 2018). Later molecular studies supported the monophyly of these groups. ( Tian et al. 2022).

The two new species from the Central Ryukyus exhibit a unique combination of morphological characters that set them apart from the previously known species groups. Our molecular analysis further supports this distinction placing these species in a monophyletic clade, separated from the other existing species groups (Fig. 12 ). Based on these findings, we propose a new species group, the Solenysa yambaruensis group, to accommodate the two Ryukyuan species.

Figures

Figure 12. Phylogenetic tree based on combined COI and H 3 gene fragments reconstructed using maximum likelihood (ML) on RAxML and Bayesian inference (BI) on MrBayes. Support at each node denotes the ML bootstrap value (BV) and BI posterior probability (PP). Nodes highly supported by at least one method (BV ≥ 75 or PP ≥ 0.95) are highlighted by a black dot, nodes with medium support (BV ≥ 70 or PP ≥ 0.90) are reported in grey, low supported nodes lack a dot. Branch lengths were scaled to the number of substitutions per site. Solenysa species groups are highlighted with different colors. New taxa discussed in this work are reported in red.