Acrotrichis Motschulsky, 1848

Darby, Michael, 2015, Studies of Bolivian Ptiliidae (Coleoptera) 2: The subfamily Acrotrichinae including two new genera Petrotrichis and Microtrichis, and eight new species of Acrotrichis, Zootaxa 3999 (2), pp. 190-210 : 192

Acrotrichis Motschulsky, 1848

Unless stated otherwise all species share the following features: body elongate, usually rather broad, relatively flat, dorsal surface including the head pubescent. Antennae with 11 segments 1–2 forming the scape and pedicel being much larger than 3–11, and 9–10 forming a loosely formed and tapering club; all segments bearing long setae. Sides of pronotum with a narrow raised margin, and hind angles produced backwards. Scutellum without distinguishing features. Metascutellum with a single lateral spine or spur on each side (not present in any other Ptiliidae subfamily (Hall, 2000)). Elytra truncate apically exposing +/- 4 abdominal segments. Proventrum narrow in front of the procoxae. Mesoventrum with a well developed collar extending across the pleura and a raised keel between the mesocoxae. Metasternum pubescent, posterior margin between the metacoxae with sharp lateral points. Metacoxae with rounded plates tapering towards the lateral margins. Abdominal tergites two-five with wing folding spicule patches. Pygidium composed of tergites nine and ten fused seamlessly together with or without 2/3 teeth. Abdominal ventrite one without femoral lines. Male ventrite six with a more or less curved excision, ventrite seven small, covering the excision in ventrite six, and with an anteriorly directed apodeme. Aedeagus symmetrical in dorsal/ventral view often, but not always, with two hooks. Spermatheca well developed. Wings of usual featherwing type. Parthenogenetic species have been recorded.

Several attempts have been made to establish subgenera and, more recently, species groups within specific geographic faunas. However, the validity of some these classifications is questionable if a more holistic view is taken and allowance made for new criteria resulting both from the discovery of many new species and also from better descriptions of old ones. For this reason and until the genus is better understood no attempt is made here to assign species to particular groups and they are treated instead in one alphabetic sequence. Further information together with a more detailed account of the morphological features useful in separating species of Acrotrichis is included in Darby (2014).