Arachnologische Mitteilungen 54

26 R. Breitling M. foxi / M. rossica , which is not distinguished by the barcode sequences. In this case, the two Alaskan M. rossica specimens may be misidentified (G. Blagoev pers. comm.), and two Rus- sian specimens of M. rossica added to the database after the conclusion of this study are clearly distinct, but still sister to M. foxi . Most importantly, the species groups identified ear- lier, based on morphological analyses (Wunderlich 1980) and in the first morphology-based phylogenetic analysis of the genus (Platnick & Shadab 1988), are consistently recovered in the majority of the phylogenetic analyses whenever the necessary barcode sequences are available. This concerns the pulicaria group (represented by M. pulicaria, M. elizabethae, M. gertschi, M. constricta and M. tripunctata; only M. aenea seems to be misplaced in this group, and Wunderlich (1980) had already indicated a possible closer relationship to the sub- opaca group, as recovered here), as well as the scenica group (represented by M. foxi and M. rossica ). Other consistently recovered clades, such as the one joining M. constricta and M. gertschi (bootstrap support 74 to 96%), and the one joining M. longipes and M. alpina (bootstrap support 36 to 71 %), indica- te the value of DNA barcoding in highlighting potential re- lationships that are not immediately obvious morphologically. Restoring the monophyly of Micaria with regard to Arbo- ricaria as currently defined would require splitting the genus into at least five individual genera (for an extended pulicaria group [ Micaria s. str.], an extended dives group [ Micariolepis ] , the subopaca group [ Arboricaria ] , and new genera for the lon- gipes group and for M. aenea ), and possibly more, as several species groups are not yet represented in the DNA dataset, nor in earlier morphological analyses. Given the notable mor- phological homogeneity of the genus Micaria s. lat., as well as its distinctive morphological and ecological synapomorphies pointed out by Wunderlich (2017) – e.g., squamose and iri- descent hairs, diurnal life style and ant-mimicry – such an ex- cessive splitting of the genus would be undesirable, turning a clearly differentiated genus into a complex of poorly resolved genera that would be very challenging to diagnose reliably. One could, of course, argue that the results are weakened by the absence of the type species of Arboricaria , i.e. A. cyrnea , in the barcode dataset. However, as Arboricaria was explicit- ly established for “the species from the former M. subopaca - group” (Bosmans & Blick 2000), even if A. cyrnea would turn out to be the sister species of all the Micaria species conside- red here, the resulting drastic re-definition and relimitation of Arboricaria would seriously undermine its taxonomic use- fulness. It is noteworthy that the molecular phylogeny places M. dives close to the root of Micaria , compatible with M. dives (plus the scenica group) being the sister to all other Micaria species. M. dives could therefore with some justification be placed in its own genus Micariolepis Simon, 1879, as had been suggested by Simon (1878, sub Chrysothrix , preoccupied) and followed by numerous later authors (e.g., Reimoser 1937, Buchar 1962, Brændegård 1966, Miller 1971). But even then, the sequence analyses indicate that maintaining monophy- ly of Micaria would either require establishing an additional new genus for the scenica group or the extension of Micari- olepis to include the scenica group at the cost of losing mor- phological diagnosability. Moreover, the morphological gap separating Micariolepis and the analysed representatives of the scenica group from the rest of Micaria is at best very narrow and the unambiguous diagnosis of Micariolepis so challenging (Wunderlich 1980) that such a formal separation would be hardly informative and is better avoided. In conclusion, the molecular barcoding data fully vin- dicate the suspicions raised by Platnick (2001) and support Wunderlich’s (2017) decision to formally treat Arboricaria as a subjective junior synonym of Micaria ( syn. conf. ). The decision to perform analyses using non-optimized default parameters and to combine results from a diverse set of methods into a single consensus tree should alleviate con- cerns regarding the possibility of fine-tuning or cherry pi- cking the results in favour of the preferred outcome. But it also means that there is considerable room for improvement should there be interest in a more comprehensive phylogene- tic analysis of Micaria and gnaphosids in general: ideally, such a study would include an even wider range of species, additi- onal genes (including nuclear ones), and carefully optimized alignments and parameters, while being restricted to the most appropriate phylogenetic inference methods, including Baye- sian approaches, which because of computational constraints were not included in the present study. The case of Arboricaria illustrates the value of barcoding information beyond its primary purpose of documenting biodiversity and assisting species identification and discovery (Hebert et al. 2003). While the molecular data in isolation will not be able to replace traditional, integrative taxonomy (Will et al. 2005, Ebach & de Carvalho 2010), they can pro- vide highly valuable complementary information to resolve long-standing taxonomic problems in arachnology (Padial & de la Riva 2007). A systematic analysis of the publicly availab- le data will certainly reveal numerous analogous cases in other spider taxa in the near future, and as the availability of data increases similar studies should soon become part of taxono- mic routine in arachnology. Acknowledgements Gergin Blagoev, Theo Blick, Robert Bosmans, Norman Platnick, and Jörg Wunderlich provided helpful comments on an earlier version of the ma- nuscript. I also thank Jonas Astrin and an anonymous referee for their con- structive suggestions that helped improving the analysis. 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