Placusa Erichson, 1837

Gao, Jiangyong, Ji, Baozhong & Liu, Shuwen, 2011, A new species of Placusa Erichson (Coleoptera, Staphylinidae, Aleocharinae) from China, Zootaxa 3094, pp. 43-51 : 44

Genus Placusa Erichson, 1837

Type species: Placusa pumilio Erichson 1837

Diagnosis. This genus is distinguished by the following combination of characters: 1) tarsal formula 4-4-5, metatarsus with basal segment elongate and at least as long as the two following segments combined ( Ashe 1991, Klimaszewski 2001); 2) pronotum transverse, from one-half to two-thirds broader than long, base arcuate, pubescence usually short and dense, directed approximately straight posteriad, sometimes obliquely laterad, particularly near the posterior part of the median line and the base of the disc ( Klimaszewski 2001); 3) antenna with last segment flattened, broad moderately elongate ( Klimaszewski 2001); 4) procoxal cavities open behind; mesosternum short, projecting to a maximum of half the mesocoxal length, narrowly triangular and pointed; mesocoxae in contact medially ( Klimaszewski 2001); 5) the labral chaetotaxy with the number of setae arranged in a pattern ( Ashe 1991); 6) mandible with dorsal molar area modified to transverse rows of large teeth and with defined distribution of dorsal sensory pores ( Ashe 1991); 7) maxillary palpi 4-segmented, basal segment small, apical segment narrowly elongate and about half the length of the preapical segment ( Ashe 1991); 8) labial palpi 2-segmented and very short ( Ashe 1991); 9) ligula short, broadly rounded ( Ashe 1991); 10) labium with lateral pseudopores and prementum reduced ( Ashe 1991); 11) male tergite 8 with a variable number of small to large spines-dents ( Johnson 1968, Klimaszewski 2001); 12) median lobe of aedeagus with narrowly elongate, appendage-like structure, rather loosely connected to the anterior bulbus between bases of parameres ( Klimaszewski 2001); 13) flagellum long and multiply coiled basally ( Tachyporoides group) or short and inconspicuous (Canadensis group) ( Klimaszewski 2001); 14) spermatheca simple, capsule small and approximately spherical, duct sinuate and sometimes with irregular posterior coils ( Klimaszewski 2001).