Nesticella Lehtinen & Saaristo, 1980

Lin, Yucheng, Ballarin, Francesco & Li, Shuqiang, 2016, A survey of the spider family Nesticidae (Arachnida, Araneae) in Asia and Madagascar, with the description of forty-three new species, ZooKeys 627, pp. 1-168 : 12-13

Taxon classification Animalia Araneae Nesticidae

Genus Nesticella Lehtinen & Saaristo, 1980

Nesticella Lehtinen & Saaristo, 1980: 55; Wunderlich 1986: 93; Gray 1989: 88; Marusik and Guseinov 2003: 37.

Type species.

Nesticus nepalensis Hubert, 1973 from Nepal.

Diagnosis.

Nesticella belongs to the tribe Nesticellini sensu Lehtinen & Saaristo (1980). The characters are rather variable within the different species-groups of Nesticella , however males can be recognized by the presence of a complex paracymbium usually lacking any dorsal apophysis (a few species with only one), with a simple or bifurcate distal process and one or two ventral processes. By contrast, males of the other small-sized nesticid genera distributed in the Old World ( Hamus , Nescina , Wraios ) have a shorter and more compact paracymbium. The uncoiled embolus instead of a long and coiled embolus, easily separate Nesticella from the small Pseudonesticus species. Females of Nesticella are recognized by the short, rectangular or lobed and often protruding scape and by the general shape of the copulatory ducts with thick, compact copulatory ducts lacking deep convolutions and located just below the coiled, thin fertilization ducts. The above-mentioned characters are not similar to any other genus of Nesticidae .

Description.

Total length: 1.60-2.94 (male), 2.00-3.36 (female). Carapace almost round in males, ovate in females, yellow or pale yellowish, only rarely dark. Cephalic area slightly elevated with sparse setae. Eight eyes in two rows with exceptions in cave-adapted species, ALE>PLE=PME>AME. AER slightly procurved, PER straight MOA trapezoidal, narrower in the front. In troglobitic species (e.g. Nesticella caeca sp. n., Nesticella gazuida sp. n.) eyes strongly reduced with AME sometimes absent. Cervical groove and fovea usually distinct, sometimes indistinct. Chelicera with three promarginal teeth and multiple retromarginal tiny denticles. Opisthosoma with long setae usually with a yellowish or greyish background and pairs of dark spots partially merged each other on the dorsal side, in some species uniformly black or greyish. Colors and marks can be more or less visible and sometimes reduced to being faint.

Male palp: tibia short and swollen, wider than long, with three retrodorsal trichobothria and sparse long setae. Cymbium with dense and thick long setae dorsal-distally. Paracymbium compact with a stocky, laminar or bifurcate distal process and a ventral apophysis with one or two processes of different length. Dorsal apophysis absent in some species. Terminal apophysis blunt, crest-like or elongate and pointed. Tegular apophysis usually well-developed, missing in mogera and quelpartensis -groups. Tegulum with a small additional tegular apophysis (Tg-II) in the species belonging to the nepalensis -group. Conductor long and curved, basally wide, gradually narrower near the tip, sometimes distally twisted and always with a sclerotized, short beak-shaped process. Embolus long and filamentous, starting from the retroventral margin of the tegulum and coiling with a half loop until reaching the apex of the conductor.

Epigyne: weakly sclerotized showing the internal structures. Scape lobed or squared, sometimes strongly reduced, sometimes well-developed. Copulatory openings at the lateral corners of the scape, under the scape in the phami -group. Spermathecae ovoid or almost round, usually small. Fertilization ducts long and thin reaching the spermathecae with one to five coils. Copulatory ducts short and thick, ventrally oriented, sometimes bent in the middle and directed laterally.

Distribution.

Mostly Pantropical (Brazil; Central and East Africa; East, South and Southeast Asia; Indochina; Melanesia) with few species occurring in the Russian Far East. Nesticella mogera is also found in Azerbaijan, Fiji, Hawaii and Europe, probably introduced by human activities.

Remarks.

Although the morphological characters of Nesticella species may support the hypothesis of two possible distinct genera as claimed by Lehtinen and Saaristo (1980) and Marusik and Guseinov (2003), the variability within this group is wide, and a further analyses that incorporate molecular data are required to solve the question. Therefore, we prefer to follow the current classification as given in the World Spider Catalog (2016) with all the species included in a single genus corresponding to the tribe Nesticellini sensu Lehtinen & Saaristo (1980). We propose five species-groups ( brevipes , mogera , nepalensis , phami and quelpartensis -groups) based on male palpal and epigynal morphology and preliminary results of our molecular analysis of the entire Nesticidae . Two species-groups already established by Lehtinen and Saaristo (1980) ( brevipes -group and mogera -group) are followed while the nepalensis -group coincides with the genus Nesticella sensu Lehtinen & Saaristo (1980). Two more new groups ( phami -groups and quelpartensis -group) are here established.

Incertae sedis.

Two recently-described species from Laos and Myanmar, Nesticella foelixi Grall & Jäger, 2016 and Nesticella michaliki Grall & Jäger, 2016, show peculiar palpal and epigynal characters which don’t allow their clear placement into any Nesticella species-group in this paper. Some characters, such as shape of the scape, the wide spermathecae and the flat distal process of the paracymbium, are shared with phami -group species; however the thick embolus, the general shape of the process of the conductor, the terminal apophysis and the paracymbium are not shared with this species group. It is possible that these new species represent separate monospecific species-groups. Nevertheless, in absence of further data, these species are temporarily considered as incertae sedis until further analyses have been conducted.