Walckenaeria (Tigellinus) trivialis, Tanasevitch, 2023

Tanasevitch, Andrei V., 2023, Survey of the Ethiopian linyphiid spider fauna. I. Subfamily Erigoninae (Arachnida, Araneae, Linyphiidae), Zootaxa 5346 (4), pp. 420-442 : 437-440

Walckenaeria (Tigellinus) trivialis new species

Figs 13 , 14

Type material. Holotype: J ( ZMMU): Oromia Region, Asela Zone, ca 7–8 air-km EES from Asela (= Assela), Chilalo Mt., canyon, steep northern slope, 3070–3075 m a.s.l., 7.935124°N 39.19392°E, Hypericum revolutum bushes with sporadic Schefflera abyssinica , grass, green mosses, sifting litter and mosses, 29.X.2022, leg. A. Tanasevitch [Eth016] . Paratypes: 1J ( ZMMU): same date and locality, together with holotype; 2♀ ( ZMMU): Chilalo Mt., canyon branch, SE slope, 3125–3130 m a.s.l., 7.93414°N 39.19479°E, Hypericum revolutum bushes with sporadic Schefflera abyssinica and Hagenia abyssinica , grass, green mosses, sifting litter and mosses, 29.X.2022, A. Tanasevitch leg. [Eth017]; 1J ( ZMMU): Arsi Mountains N.P., road from Digelu to Ticho, 3500–3505 m a.s.l., 7.81944°N 39.35429°E, Erica arborea bushes, grass, green mosses, sifting mosses, 30.X.2022, A. Tanasevitch leg. [Eth018].

Etymology. The specific epithet is a Latin adjective referring to the shape of the male carapace typical for the subgenus Tigellinus Simon, 1884 of Walckenaeria Blackwall, 1833 .

Diagnosis. Based on the shape of the carapace (see Figs 13A–E ), the new species belongs to the subgenus Tigellinus . Presently, at least 12 of the 18 Walckenaeria species currently known from the Afrotropical Region belong to Tigellinus . All of these species are extremely similar to each other, mainly differing by the presence or shapes of the dorsal palpal tibial outgrowth(s) and, partly, by the shape of a “turret” on the carapace.

The new species seems to be most similar to the Tanzanian Walckenaeria (Tigellinus) uzungwensis Scharff, 1990 , but is distinguishable by a wider distal part of the “turret” of the carapace, by the presence of an additional outgrowth on the palpal tibia (AO in Figs 14C–E ), as well as by the somewhat longer embolus. The female differs well by the non-enlarged eyes and the considerably less spaced receptacles.

Description. Male (Paratype from Eth016). Total length 2.00. Carapace modified, as shown in Figs 13A–E , 0.93 long, 0.72 wide, pale brown to brown, carapace with a “turret”. Eyes slightly enlarged. Chelicerae 0.30 long, a mastidion absent. Legs brown. Leg I 2.57 long (0.68 + 0.25 + 0.63 + 0.58 + 0.43), IV 2.84 long (0.75 + 025 + 0.73 + 0.68 + 0.43). Chaetotaxy 2.2.1.1, spines about as long as 1–1.5 diameter of corresponding leg segment. Metatarsi I–IV with a trichobothrium each. TmI 0.50. Palp ( Figs 14A–E ): Tibia with a sickle-shaped prolateral process, and a small denticle at its base; dorso-retrolaterally with a small projection of different shape depending on an angle of view (AO in Figs 14C–E ). Paracimbium L-shaped. Distal suprategular apophysis relatively short, narrowing distally. Median membrane short, poorly visible. Radix fusiform, with a long tailpiece. Embolus long, forming a loop, with a small, narrow, transparent “ligula”-shaped outgrowth at its base (L in Figs 14A, B ). Opisthosoma 1.13 long, 0.70 wide, grey, as in Fig. 13A .

Female (Paratype from Eth017). Total length 2.45. Carapace unmodified ( Fig. 13F ), pale brown, 1.00 long, 0.78 wide. Chelicerae 0.38 long. Legs pale brown. Leg I 2.60 long (0.80 + 0.30 + 0.55 + 0.55 + 0.40), IV 3.07 long (0.83 + 0.28 + 0.80 + 0.73 + 0.43). Chaetotaxy 2.2.1.1, spines about as long as 1–1.5 diameter of corresponding leg segment. Metatarsi I–IV with a trichobothrium each. TmI 0.55. Opistosoma 1.60 long, 1.08 wide, grey, as in Figs 13F, G . Epigynum ( Figs 13 G–I , 14F ): Epigynal plate oval, receptacles and seminal ducts well-sclerotized.

Distribution. Known from the mountains of Oromia Region, Ethiopia, 3070–3505 m a.s.l.

Figures

FIGURE 13. Photographs of male paratype from Eth016 (A–E) and female paratype from Eth017 (F–I) of Walckenaeria (Tigellinus) trivialis n. sp. A, F, habitus, dorsal view; B, prosoma, dorsal view; C, same, frontal view; D, E, same, lateral view, different specimens; G, habitus, ventral view; H, I, epigynum, ventral and dorsal view, respectively. Scale bars: A–G, 0.5mm; H, I, 0.1mm.

FIGURE 14. Details of male palpal structure (A–E) and female epigynum (F) of Walckenaeria (Tigellinus) trivialis n. sp., male paratype from Eth018, female paratype from Eth017. A, B, right palp, retrolateral and prolateral view, respectively; C, D, tibia, dorsal view; E, same, dorsolateral view; F, cleared epigynum, dorsal view. Scale bars: 0.1mm.