Microcyba oromia, 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 : 430-431

Microcyba oromia new species

Figs 7 , 8

Types. Holotype: J (ZMMU), ETHIOPIA, Oromia Region, Asela Zone, ca 34–35 air-km SE from Asela (= Assela), Arsi Mountains N.P., road from Digelu to Ticho, top of mountains, 3755–3770 m a.s.l., 7.82377°N 39.41713°E, Erica arborea bushes, Alchemilla sp. , green mosses mostly Rhytidiadelphus triquetrus , sifting mosses in beds of Erica , 21.X.2022, A. Tanasevitch leg. [Eth019] . Paratypes: 1J, 8♀ (ZMMU), same date and locality, together with holotype; 1J, 4♀ (ZMMU), Oromia Region, Asela Zone, ca 32 air-km SE from Asela, Arsi Mountains N.P., road from Digelu to Ticho, top of mountains, 3780–3866 m a.s.l., 7.82472°N 39.41659°E, Erica arborea bushes, sedge, Alchemilla sp. , green mosses, sifting humus and mosses, 18.X.2022, A. Tanasevitch leg. [Eth010]; 2J, 2♀ (MHNG), Asela Zone, ca 30 air-km SE from Asela, 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, leg. A. Tanasevitch [Eth018].

Etymology. The specific epithet is a noun in apposition referring to the Oromia Region, Ethiopia, the area of origin of the species.

Diagnosis. The male of the new species is diagnosed by the C-shaped palpal tibia when viewed from above (also known only in M. projecta Holm, 1962 ), by the peculiar structure of the embolic division in the male, namely, by the shape of a relatively long embolus, and the presence of an outgrowth at its base. The female is distinguishable by the presence of two protrusions (PP in Figs 7E–F , 8F, G ) of the dorsal plate extended from under the ventral plate. The male of M. oromia n. sp. seems to be most similar to M. projecta , known from Uganda ( Holm 1962), but differs by the presence of a truncate process on the retrolateral side of the palpal tibia, as well as by a straight and longer embolus (vs screw-shaped). The female of the new species is very similar to that of M. magna sp.n., but is readily distinguishable by the smaller size (1.35 vs 1.70), the shorter epigynum, the less spaced receptacles, as well as by the presence of two protrusions of the dorsal epigynal plate extended from under the ventral plate.

Description. Male (Paratype from Eth019). Total length 1.28. Carapace modified, as shown in Figs 7A–C , 0.60 long, 0.53 wide, brown to reddish-brown, with radial stripes, high in lateral view, with a sharp slope at its back. Clypeus high, vertical. Sulci very small, poorly visible. Eyes relatively small. Chelicerae 0.23 long, a mastidion absent. Legs pale brown. Leg I 1.55 long (0.45 + 0.36 + 0.17 + 0.30 + 0.27), IV 1.47 long (0.42 + 0.15 + 0.36 7+ 0.30 + 0.24). Chaetotaxy 1.1.1.1, spines about as long as diameter of corresponding leg segment. Metatarsi I–III with a trichobothrium each. TmI 0.45. Palp very small ( Figs 8A–E ): Tibia C-shaped in dorsal view, with a long, serrate, tapering distally prolateral process, retrolateral outgrowth abruptly ending. Paracymbium small, narrow, L-shaped. Distal suprategular apophysis short, sharpened distally. Median membrane short and wide. Embolic division Zshaped, proximal part of radix broadened; distal part with a black outgrowth at base of embolus. Embolus relatively wide, narrowing distally. Opisthosoma 0.70 long, 0.55 wide, grey ( Figs 7A, B ).

Female (Paratype from Eth019). Total length 1.35. Carapace 0.58 long, 0.50 wide, brown to reddish-brown, with radial stripes, high in lateral view, with a sharp slope at back. Clypeus high, vertical. Chelicerae 0.28 long. Legs pale brown. Leg I 1.43 long (0.42 + 0.15 + 0.33 + 0.27 + 0.26), IV 1.52 long (0.44 + 0.15 + 0.38 + 0.29 + 0.26). Chaetotaxy 1.1.1.1, spines about as long as diameter of corresponding leg segment. Metatarsi I–III with a trichobothrium each. TmI 0.44. Opisthosoma 0.90 long, 0.68 wide, grey to dark grey ( Fig. 7D ). Epigynum ( Figs 7E, F, G , 8F, G ) well-sclerotized, slightly protruded, ventral plate tapering wedge-shaped posteriorly. Dorsal plate posteriorly with two protrusions extended from under the ventral plate. Receptacles subspherical.

Distribution. Known only from the highlands of Arsi Mountains N.P. (3500–3866 m a.s.l.), Oromia Region, Ethiopia.

Figures

FIGURE 7. Photographs of male (A–C) and female (D–G) of Microcyba oromia n. sp., paratypes from Eth019. A, D, habitus, dorsal view; B, same, lateral view; C, prosoma, frontal view; E, F, opisthosoma, ventral view, different specimens; G, epigynum, ventral view. Scale bars: A–F, 0.5mm; G, 0.1mm.

FIGURE 8. Details of male palpal structure (A–E) and female epigynum (F, G) of Microcyba oromia n. sp., paratypes from Eth010. A, B, right palp, retrolateral and prolateral view, respectively; C, distal part of palp, retrolateral view; D, tibia, and paracymbium, prolateral view; E, tibia, dorsal view; F, G, epigynum, ventral and dorsal view, respectively. Scale bar: 0.1mm.