﻿On the synonymy of Dactylopisthoides Eskov, 1990 and Uusitaloia Marusik, Koponen & Danilov, 2001 (Araneae, Linyphiidae)

﻿Abstract Two erigonine genera from East Siberia are synonymized: Uusitaloia Marusik, Koponen & Danilov, 2001, syn. nov. = Dactylopisthoides Eskov, 1990. Two new combinations are established: Dactylopisthoidestransbaicalicus (Marusik, Koponen & Danilov, 2001), comb. nov. and Dactylopisthoideswrangelianus (Marusik & Koponen, 2009), comb. nov. both ex. Uusitaloia. The epigyne of D.wrangelianus is illustrated for the first time. A new, updated diagnosis of Dactylopisthoides is proposed. The copulatory organs of both sexes of D.hyperboreus and D.wrangelianus are illustrated by SEM images.


Introduction
The erigonine genus Uusitaloia Marusik, Koponen & Danilov, 2001 was established for Uusitaloia transbaicalica Marusik, Koponen & Danilov, 2001, a species that was described from the holotype male from the region of Lake Baikal, Buryatia, Russia (Marusik et al. 2001).The second congener, U. wrangeliana Marusik & Koponen, 2009, was described from Wrangel Island, Russia (Marusik and Koponen 2009).A detailed re-examination of the type materials of both Uusitaloia species has revealed that their conformation of the copulatory organs in both sexes is similar to that of the generotype of the monotypic genus Dactylopisthoides Eskov, 1990, known from the upper reaches of the Kolyma River.This paper is aimed at (1) establishing a synonymy of these genera, and (2) providing an updated diagnosis of the genus Dactylopisthoides.

Material and methods
This paper is based on the collections deposited in the Zoological Museum of the Moscow State University, Moscow, Russia (ZMMU), and the specimens that are temporary in the Zoological Museum of the University of Turku, Finland (ZMUT).Specimens preserved in 70% ethanol were studied using an MBS-9 stereo microscope.Photographs were taken using a SEM JEOL JSM-5200 scanning microscope at the ZMUT.Leg chaetotaxy is presented as follows: e.g., 2.2.2.1, referring to a number of dorsal spines on tibiae I-IV.Terminology of the copulatory organ sclerites largely follows Merrett (1963) as well as the authors indicated in the abbreviations given below.
Comments.An analysis of both somatic and copulatory organ structures of the type species of Uusitaloia and Dactylopisthoides has revealed that they are undoubtedly congeneric: all the species in both genera are of a similar small size, possess the same chaetotaxy (2221) and trichobothriotaxy (I-III; TmI: 0.64-0.65),and are characterized by the same conformation of copulatory organs in both sexes, differing from each other only in minor details: cf.Figs 1-3.Thus, the genus Uusitaloia Marusik, Koponen & Danilov, 2001 is to be considered a junior synonym of Dactylopisthoides Eskov, 1990.
In the papers dealing with Dactylopisthoides (Eskov 1990) and Uusitaloia (Marusik et al. 2001;Marusik and Koponen 2009), the authors provided different tibial chaetotaxy even for different sexes.The reason for this appears to have been the small size of the spines, which could be easily overlooked (for further details, see Tanasevitch 2022).
Distribution.From north-eastern Transbaikalia to Wrangel Island (Fig. 4).Its occurrence in Yakutia and Kamchatka is very likely.Comments.This species has been known from a single taxonomic entry.
Comments.No SEM figures are provided for this species, as it remains known from the holotype male only.
Distribution.Only the type locality, Transbaikalia, Russia.