Pelecopsis arsi Tanasevitch 2023, new species
Creators: name: Tanasevitch, Andrei V.
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Linyphiidae
Pelecopsis
Pelecopsis arsi

description: Pelecopsis arsi new species
Figs 9, 10
Type material. Holotype: J (ZMMU): ETHIOPIA, Oromia Region, Asela Zone, ca 35air-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 from beds of Erica, 21 & 31.X.2022, A. Tanasevitch leg. [Eth019]. Paratypes: 1J, 1♀ (ZMMU): same locality, together with holotype.
Etymology. The specific epithet is a noun in apposition referring to the Arsi Mountains N.P., the area of origin of the new species.
Diagnosis. The new species can easily be assigned to Pelecopsis Simon, 1864, based on the same chaetotaxy (1.1.1.1), a similarly modified carapace, the presence of an abdominal scutum in the male, as well as by a similar conformation of the male palp, i.e., a modified palpal tibia, a fusiform embolic division with a long tailpiece and a coiled embolus. The shape of the median epigynal plate in the female is similar to that of most of the Afrotropical congeners.
The structure of the male palp is uniform in all members of the genus, differences between specific lying in minor details of the palpal tibia, cymbium, tailpiece, and embolus. The structure of the palp, especially that of the embolic division of P. arsi n. sp., resembles that of many congeners, but the new species is clearly distinguished amongst the known members of the genus, by the presence of a cuticula-free space, i.e. a rectangular glandular area on the face of the male carapace (see Figs 9D, E). Such a prosomal structure I know of is only observed in the North African P. pavesii Bosmans & Hervé, 2021, from Tunis, but its glandular area is divided into two narrow and poorly visible parts. Besides this, the male of P. arsi n. sp. differs by the shape of the palpal tibia when viewed from above, the highest (among Afrotropical congeners) dorsal tubercle on the proximal part of the cymbium, as well as by the large and complex median membrane which protrudes far beyond the palp. As the epigynum of the female resembles that in many Afrotropical congeners, e.g., P. hamata Bosmans, 1988, P. humiliceps Holm, 1979, P. infusca Holm, 1962, P. pasteuri (Berland, 1936), etc., a reliable determination of this species seems to be possible only in the presence of a conspecific male.
Description. Male (Paratype from Eth019). Total length 1.88. Carapace modified, as shown in Figs 9A–E, 0.88 long, 0.65 wide, brown to reddish-brown, with dark radial stripes. Head part of carapace with a pale and rounded elevation bearing posterior median eyes. A pale, cuticula-free, rectangular field placed above anterior median eyes and probably representing a glandular area. Sulci small, rounded. Eyes normal, not enlarged. Chelicerae 0.33 long, a mastidion absent. Legs brown to pale brown. Leg I 1.98 long (0.55 + 0.25 + 0.45 + 0.40 + 0.33), IV 2.32 long (0.65 + 0.23 + 0.58 + 0.53 + 0.33). Chaetotaxy 1.1.1.1, spines very short, poorly visible. Metatarsi I–IV with a trichobothrium each. TmI 0.68. Palp (Figs 10A–E): Patella long, gradually expanding towards its distal edge. Tibia extended distally into a long, narrow and conical process, claw-shaped apically; prolateral edge of patella with very small denticles. Paracymbium small, narrow, curved forming a loop. Distal suprategular apophysis relatively short and narrow. Median membrane very large, complex, protrudes far ahead. Embolic division fusiform, tailpiece narrow, pointed proximally. Embolus long, slightly expanded at middle, with a small membraneous widening apically. Opisthosoma 1.13 long, 0.58 wide, dark grey, 3/4 covered with a scutum, as in Figs 9A–C.
Female (Paratype from Eth019). Total length 2.10. Carapace unmodified, dark brown, almost black, 1.23 long, 0.58 wide. Chelicerae 0.30 long. Legs brown. Leg I 2.09 long (0.60 + 0.25 + 0.48 + 0.43 + 0.33), IV 2.54 long (0.73 + 0.25 + 0.63 + 0.58 + 0.35). Chaetotaxy 1.1.1.1, spines about as long as 0.5–1 diameter of corresponding leg segment. Metatarsi I–IV with a trichobothrium each. TmI 0.71. Opistosoma 1.40 long, 1.13 wide, dark grey, scutum absent, muscle spots distinct, small, as in Figs 9F. Epigynum (Figs 9G, H, 10F, G): Anterior wall with a projection dividing the epigynal socket almost into two parts, receptacles subspherical, widely spaced.
Distribution. Known only from the type locality in the highlands of Arsi Mountains N.P. (3755–3770 m a.s.l.), Oromia Region, Ethiopia.
description: Published as part of Tanasevitch, Andrei V., 2023, Survey of the Ethiopian linyphiid spider fauna. I. Subfamily Erigoninae (Arachnida, Araneae, Linyphiidae), pp. 420-442 in Zootaxa 5346 (4) on pages 433-434, DOI: 10.11646/zootaxa.5346.4.4, http://zenodo.org/record/8390441