PAPUSINI JAŁOSZYŃSKI & BRUNKE, 2018

Jałoszyński, Paweł, Brunke, Adam J., Yamamoto, Shûhei & Takahashi, Yui, 2018, Evolution of Mastigitae: Mesozoic and Cenozoic fossils crucial for reclassification of extant tribes (Coleoptera: Staphylinidae: Scydmaeninae), Zoological Journal of the Linnean Society 184, pp. 623-652 : 635

PAPUSINI JAŁOSZYŃSKI & BRUNKE TRIB. NOV.

urn:lsid:zoobank.org:act:9346A6D8-168A-4FAD-8491-7D7152B6D7BE

Type genus: Papusus Casey, 1897 , here designated.

Diagnosis

Papusini differs from all remaining Mastigitae genera by the unique, very large compound eyes located at the middle, or slightly behind the middle, of the head capsule, and a set of synapomorphies known (in different combinations) in other tribes: scape about as long as head, lacking bristles; pedicel not enlarged; maxillary palpomere 3 strongly elongate, with its apical margin nearly perpendicular to the long axis of palpomere, gradually broadening distally; maxillary palpomere 4 subtriangular, broadest at base, much shorter than 3 and distinctly narrower than 3 at apex; vertex and frons lacking median longitudinal groove; posterior margin of vertex lacking a pair of modified setae or large chaetopores; pronotum lacking posterior collar; mesoventral intercoxal process elongate, slender and parallel-sided; posterior margins of mesocoxal cavities carinate; mesocoxa with longitudinal row of several (typically 5) long and thick bristles; admetacoxal margin of metaventrite at each side with indistinct expansion (i.e. not evenly concave but slightly angulate near the mesal third of metacoxa); elytra with longitudinal rows of shallow punctures; aedeagus symmetrical, with slender parameres and straight flagellum.

Remarks

The placement of Papusus has been problematic for the past 120 years. Casey (1897) placed it in Clidicini , based on a similar form of the maxillary palpomere 4 of Papusus to that of Clidicus . Franz (1985) transferred Papusus to Scydmaenini of Scydmaenitae, but later synonymized it under Leptochromus , automatically moving it back to Clidicini . Papusus was resurrected as a valid name and separate genus by O’Keefe (1998), who carried out a phylogenetic analysis focused on resolving relationships between species of Papusus , but used only Leptochromus as the outgroup. Later, O’Keefe (2002) proposed a sister-group relationship between Papusus and († Palaeoleptochromus + Leptochromus ), but his analysis was restricted to three genera only, with Clidicus as the outgroup. A broader taxon sampling was done by Jałoszyński (2012a, 2016b), who included all genera of Mastigitae known at that time and obtained ambiguous results concerning the placement of Papusus . It was placed, with equal parsimony, as (1) a sister-group to all remaining Clidicini (in a broad, traditional sense) vs. (2) sister to Leptomastacini + all remaining Clidicini ( Jałoszyński, 2012a) , or as (3) sister to Leptomastacini vs. (4) sister to a clade Clidicus + (remaining Clidicini + Mastigini ) ( Jałoszyński, 2016b). Consequently, Papusus remained the most problematic of all extant genera and its placement was unclear. Papusus was not placed together with the remaining genera traditionally placed in Clidicini in our phylogenetic reconstructions (neither in parsimony nor in Bayesian analyses), and although its relationships within Mastigitae are still far from being solved, it is clear that Papusus cannot be maintained as a member of Clidicini , based on: the emarginate male sternite 8; the absence of a pronotal collar; uniform setae on frons, vertex and maxillary palpomere 2; narrowly separated antennal cavities; and the presence of a row of mesocoxal bristles.