On the Australian linyphiid spider Alaxchelicera ordinaria Butler, 1932 (Araneae).

Very few studies have addressed the linyphiid fauna of Australia. Most of the existing taxonomic work on Australian linyphiids consists of isolated species descriptions (e.g., Rainbow 1912) or at most are based on small number of species also described outside a revisionary context (e.g., Wunderlich 1976) (but see van Helsdingen 1972 for a revision of the Australian species of the genera Laperousea Dalmas, 1917 and Laetesia Simon, 1908). Microctenonyx subitaneus (O. P.-Cambridge, 1875) is a Holarctic erigonine (Linyphiidae) which has been introduced in many parts of the world, including Australia (Brennan 2004). In this paper we report a new junior synonym of Microctenonyx subitaneus described by Butler (1932) under the name Alaxchelicera ordinaria Butler, 1932. In 1932 L.S.G. Butler, a Melbourne-based arachnologist, published a paper in which he described six new spider genera from Victoria and New South Wales, all of them monotypic. Three of these new genera (Microlinypheus, Plectochetos and Alaxchelicera) he placed in the family Linyphiidae, the remaining three (Platycephala, Eterosonycha and Perissopmeros) were placed in Zodariidae. Subsequent taxonomic work demonstrated that most of his original familial placements were erroneous (references in Platnick 2013). Alaxchelicera is indeed a linyphiid, but the genus is a junior synonym of Microctenonyx Dahl, 1866. Platycephala may be a zodariid, but the name is a junior homonym of Platycephala Fallén, 1820 (Chloropidae, Diptera) and it is currently listed as a nomen dubium under the replacement name Macedoniola Strand, 1932 (Platnick 2013). The type species of Microlinypheus and Plectochetos are members of the anapid genus Micropholcomma Crosby & Bishop, 1927. Eterosonycha is also a micropholcommatine anapid, not a zodariid. Perissopmeros is not a zodariid either, but a malkarid, and also a junior synonym of a genus (Sternodes Butler, 1929) that Butler himself had described in the family Palpimanidae (Moran 1986). And in yet in another nomenclatorial twist, the name Sternodes turned out to be preoccupied in the Coleoptera and in the Hymenoptera, so the valid genus name for this malkarid group is Perissopmeros. We have had the opportunity to study the holotype of Alaxchelicera ordinaria and we report here its new taxonomic status.