On the spider genus Arboricaria with the description of a new species (Araneae, Gnaphosidae)

Abstract The spider genus Arboricaria Bosmans, 2000 is redefined and an updated diagnosis given. The differences between Arboricaria and Micaria Westring, 1851 are discussed in detail. A key to all five species of the genus is provided. One new species, Arboricaria zonsteini sp. n. (♂♀), is described based on specimens from Kyrgyzstan and Azerbaijan. One new synonym is proposed: Arboricaria koeni Bosmans in Bosmans & Blick, 2000, syn. n. is assigned to Arboricaria sociabilis Kulczyński in Chyzer & Kulczyński, 1897. Data on the distribution of Arboricaria in Russia and adjacent countries are presented with references to the papers on local spider faunas.


Introduction
Arboricaria was established by Bosmans and Blick (2000) to accommodate the Micaria subopaca species group as outlined by Wunderlich (1980: 249). Five species were included, three of which had been known earlier, A. cyrnea (Brignoli, 1983) (the type species), A. subopaca (Westring, 1861) and A. sociabilis Kulczyński in Chyzer & Kulczyński, 1897, and two further described as new: A. koeni Bosmans in Bosmans & Blick, 2000and A. brignolii Bosmans & Blick, 2000. Platnick (2014, in his World Spider Catalog, does not accept this genus, because the authors provided "no evidence whatever that these taxa constitute the sister group of all other Micaria, or that the remaining Micaria do not constitute a paraphyletic group from which a relatively autapomorphic subgroup has been artificially extracted, those changes are not followed here". The same concerns the current World Spider Catalogue (WSC 2015). Arboricaria is absent from the latest world gnaphosid revision as well (Murphy 2007), albeit it has never been synonymized with Micaria.
When preparing a review of the Micaria fauna of the former Soviet Union (Mikhailov 1987), I came across a specimen from Kyrgyzstan, Central Asia which showed a bifid male tibial apophysis and apparently represented a new species. Because its generic assignment seemed obscure at that time, this specimen was excluded from my 1987 paper. However, additional material has since become available from Azerbaijan, Caucasus.
The present contribution not only provides a description of that new species, but it also aims at clarifying the distinctions between two similar genera, Micaria Westring, 1851 and Arboricaria Bosmans, 2000, so as to provide a brief review of and a key to the known species of the latter genus. In addition to Mikhailov's (1987) faunistic review, data on the distribution of Arboricaria species in Russia and adjacent countries are provided. Since most of the species included in Arboricaria are well-known and properly described, e.g. by Wunderlich (1980) within Micaria and/or by Bosmans and Blick (2000) in Arboricaria, this paper requires no redescriptions to be made and can be reduced to a key, with only short remarks given for most of species.

Material and methods
Material of three species was examined in detail: A. subopaca, A. sociabilis and A. zonsteini sp. n. Specimens were examined using MBS-9 and Olympus stereo microscopes. All initial pencil sketches drawn on scale paper were subsequently inked and then digitized with Cintiq.
Only basic and necessary synonymies are given in the species reviews below, as a more detailed list is available in WSC (2015).
Data on the distribution of Arboricaria species in Russia and Azerbaijan are mostly previously unpublished (my unpublished card Catalogue of the Spiders of Russia and Adjacent Territories; see also Mikhailov 2012Mikhailov , 2013. Only well-figured descriptions and redescriptions as well as main synonyms are listed here. Thorell, 1875, wholly absent both in M. utahna Gertsch, 1933and M. medica Platnick & Shadab, 1988. An analysis of leg spination (see table 1 in Wunderlich 1980: 250-251) shows that Arboricaria species fall within the range of Micaria variability, yet close to its marginal part. 5. The shape of the posterior part of the sternum is clearly different in Micaria and Arboricaria (see Figs 1-5). Therefore, the above diagnosis of Arboricaria must be adjusted. This genus is indeed close to Micaria, but differs in the following characters that together allow recognizing the genus: a posteriorly truncate sternum in both sexes, a bulging bulbus and a missing median apophysis, a chiefly bifid tibial apophysis, a large epigynal groove with distinctly chitinized posterior margins in females. At least, the shape of bulbus and bifid apophysis can be regarded as apomorphic characters. All these characters constitute Arboricaria as a monophyletic and sister-group to other Micaria. An extended description of Arboricaria is available in Bosmans and Blick (2000).

A median apophysis is absent or almost absent in Micaria rossica
The distribution pattern of Arboricaria is mostly Mediterranean and on the mountain regions of central Asia, although A. subopaca extends to most of the Palearctic.
Diagnosis. Gnaphosids of the "Micaria-group" (Murphy 2007), differing from Arboricaria by the more or less ovoid, posteriorly not truncate sternum in both sexes, the ovoid, not bulging bulbus with a mostly present median apophysis, the palpal tibial apophysis, sometimes poorly expressed, not bifid in males, the epigynal groove in females, if present, without distinctly chitinized posterior margins.
Composition. 101 species (WSC 2015). Distribution. Holarctic. Other records require confirmation. An analysis of the new Micaria species described from the Palaearctic since Bosmans and Blick (2000), all listed in WSC (2015), shows no match with Arboricaria characters. Therefore, despite the previous neglect of Arboricaria, no new species of this genus have been described within Micaria sensu lato since 2000. In addition, all extra-Holarctic records of Micaria are doubtful; these species most likely belonging to other genera or even families (Murphy 2007). Diagnosis. The new species differs by a combination of the following characters: Males: equally long branches of tibial apophysis with thin embolus lying on apical surface of bulbus; Females: convergent edges of epigynal groove with moderately long spermathecae, the latter being shorter than the groove, the former not reaching the fore edge of the latter.
For leg measurements, see  Epigyne and vulva as in Figs 10-11. Epigynal groove subpyriform, as long as wide, with slightly convex edges; distance between its posterior edge and epigastric furrow being ¼ of groove length. Copulatory openings small (like in most Arboricaria and Micaria), lying at lateral edges of groove in its posterior one-third. Copulatory tubes thin, almost vertical and parallel to each other, about half the length of spermathecae. Spermathecae oblong-oval, parallel to each other, being 2/3-3/4 as long as epigynal groove.

Arboricaria sociabilis Kulczyński, 1897 Figs 12-20
Micaria sociabilis Kulczyński in Chyzer & Kulczyński, 1897: 254 & 255 (key), 258-259, Tab.X., figs 21 (♀) 25a-b (♂). M. canestrinii Roewer, 1951: 447 (replacement Ponomarev). Taxonomic remarks. Originally, the male was matched with the female with some doubts (Chyzer and Kulczyński 1897), because they were taken from different, but not extremely distant localities of the former Austro-Hungarian Empire. Syntypes (1 ♂, 1 ♀, "Ungarn" = "Hungary") are listed by Wunderlich (1980), but he only redescribed the female. Comparing the epigynes of A. sociabilis and A. koeni shows no essential difference between them; therefore, these names are to be synonymized. The position of the copulatory openings is a little variable; in the type of A. sociabilis, they are closer to the middle part of the epigynal groove, in the A. koeni type and the A. sociabilis material as depicted by Pfliegler (2014) closer to the posterior one-third.
A male syntype of Micaria sociabilis from Mukachevo is currently kept in the Zoological Museum in Warsaw, Poland, but both palps are missing (W. Wawer, pers. comm.). The tibial apophysis as redrawn by Wunderlich (1980: Fig. 36a Miller (1971) in his key to Czechoslovak spiders, pointed out: "Tibial apophysis apically [sic! -KM] forked with 2 teeth, lower tooth narrower and more pointed; it is laterally slightly bent, ventrally rounded outside and bent forward and it has the same width" (translated from Czech by A. Šestaková). Miller's specimen of M. sociabilis was never depicted and is currently missing among the other Micaria samples kept in the National Museum in Prague, Czech Republic (Kůrka 1994).