Gyrohypnus punctulatus (PAYKULL, 1789) Gyrohypnus quadratus STEPHENS, 1833: 260 f.; nov.syn. T y p e m a t e r i a l: Neotype 3, present designation: " E. Ardsley, 19.v.37, WY / C.E. Tottenham collection. B.M.1974-587. / Neotypus 3 Gyrohypnus quadratus Stephens, desig. V. Assing 2017 / Gyrohypnus punctulatus (Paykull), det. V. Assing 2017" (BMNH). C o m m e n t: The original description of Gyrohypnus quadratus is based on an unspecified number of syntypes "taken in Suffolk by Mr. Kirby" (STEPHENS 1833). STEPHENS (1839) subsequently assigned the species to Xantholinus. The name is listed as a nomen dubium by HERMAN (2001) and as Xantholinus incertae sedis by SCHÜLKE & SMETANA (2015). It has not been in use since 1839 (HERMAN 2001). According to Roger Booth (e-mail, 19 January, 2017), a thorough search for the type material in both the Kirby and Stephens collections at the BMNH revealed that there is no material named as Gyrohypnus quadratus in either of the two collections. Consequently, the type material must be regarded as lost. It can be inferred from the original description that the name Gyrohypnus quadratus indeed refers to a species of Xantholinini. The details mentioned for the head ("oblong, as wide as the thorax, with confluent excavated lines"), the pronotum ("short, with about ten deep punctures on the disc, disposed in two lines", and the coloration (body, including the elytra, black with the "extreme apex [of the abdomen] reddish" suggest that G. quadratus belongs to Gyrohypnus LEACH, 1819; they clearly rule out Xantholinus (head with fine and sparse punctation; pronotum long and slender), Gauropterus THOMSON, 1860 (elytra red), and Nudobius THOMSON, 1860 (elytra reddish). Among the Gyrohypnus species distributed in Britain, the most likely candidate is G. punctulatus ("legs pitchy-black"; "Long. corp. 3 lin."). The possibility that G. quadratus refers to an overlooked species in Britain can be ruled out. Therefore, in order to dispose of an obsolete and doubtful name, a male of G. punctulatus from East Ardsley in West Yorkshire (according to Max Barclay situated at 53.7250°N, 1.5392°W) is designated as the neotype (see above) and Gyrohypnus quadratus STEPHENS, 1833 is placed in synonymy with G. punctulatus (PAYKULL, 1789).

Published as part of Assing, Volker, 2017, Taxonomic and faunistic notes on some West Palaearctic and Middle Asian Xantholinini, with a revalidation and new synonymies (Coleoptera: Staphylinidae: Staphylininae), pp. 235-252 in Linzer biologische Beiträge 49 (1) on page 238, DOI: 10.5281/zenodo.5356784