Palaeoscydmaenus Franz

Jałoszyński, Paweł, 2012, Systematic position of Australian genus Palaeoscydmaenus Franz (Coleoptera: Staphylinidae: Scydmaeninae), Zootaxa 3501, pp. 63-73 : 68-69

Palaeoscydmaenus Franz

Palaeoscydmaenus Franz, 1975: 272 . Type species: Palaeoscydmaenus australiensis Franz, 1975: 273 , monotypy.

Revised diagnosis. Palaeoscydmaenus can be identified on the basis of broad occipital constriction; lack of frontoclypeal groove; submentum demarcated laterally from hypostomae; strongly elongate maxillary palps; pronotum with rounded and not carinate lateral margins, without ante-basal foveae but with narrow and shallow ante-basal transverse groove; procoxal cavities not demarcated from basisternum and not separated in middle; mesoventrite with pair of asetose impressions and short but narrow mesoventral intercoxal process; mesocoxal projections with posterior lobes; subtrapezoidal metaventral intercoxal process with shallow median notch; elytra without basal foveae; and aedeagus with asymmetrical and complex internal sclerotized armature.

Redescription. Body ( Fig. 10 ) small (ca. 1.3 mm), elongate, strongly convex, covered with distinct setae.

Head ( Figs. 13–14 ) elongate, without thick bristles; with occipital constriction only slightly narrower than vertex; tempora about as long as eyes; vertex and frons confluent; frontoclypeal groove absent; clypeus with rounded anterior margin; compound eyes oval, distant from bases of mandibles; antennal insertions broadly separated. Gular plate subtrapezoidal, with distinct gular sutures; posterior tentorial pits located in transverse groove separating gular plate from submentum, not visible in ventral view; submentum subtrapezoidal, nearly as long as broad, laterally demarcated by complete sutures; hypostomae elongate, triangular, laterally demarcated by hypostomal ridges; mentum subtrapezoidal, transverse; labial palps with short palpomere 1, long and broad palpomere 2 and long and slender palpomere 3; maxillae with triangular basistipes, elongate lacinia and galea, maxillary palps strongly elongate, with minute palpomere 1, elongate and broadening distally palpomere 2, long and broad, pedunculate palpomere 3, and slender, subconical and pointed palpomere 4; mandibles subtriangular, with slender and curved apical tooth and small subapical tooth, prostheca and base of mandibles not visible in the studied specimen. Antennae long and slender, with indistinctly delimited club composed of antennomeres 9–11.

Prothorax ( Figs. 10–11 , 16 ) without thick bristles, in dorsal view elongate subtrapezoidal, broadest in anterior half, with all corners rounded or blunt and obtuse; pronotum without ante-basal foveae but with ante-basal transverse groove; lateral margins without marginal edges or carinae; hypomera not delimited laterally and without ventral hypomeral carinae; prosternum short, with procoxal cavities not demarcated from basisternal part and not separated in middle; procoxal sockets nearly closed.

Mesoventrite ( Figs. 11 , 17 ) with narrow anterior ridge bearing short median process not fused with mesoventral intercoxal process and with a pair of transverse asetose impressions; mesoventral intercoxal process short and narrow, with subtriangular apex not reaching middle of mesocoxae; mesocoxal projections with distinct posterior lobes, each bearing dense marginal setae; mesocoxal cavities indistinctly demarcated anteriorly and not demarcated posteriorly.

Metaventrite ( Figs. 11 , 17 ) only slightly elongate, with rounded sides and moderately concave admetacoxal parts of posterior margin; metaventral intercoxal process subtrapezoidal, with shallow median notch.

Elytra ( Fig. 10 ) oval, with weakly marked humeral calli, without basal impressions and without basal foveae.

Legs long and slender; femora distinctly clavate with slender proximal parts; all tibiae straight; tarsi long but relatively thick.

Aedeagus ( Figs. 18–19 ) stout, with lightly sclerotized median lobe, asymmetrical and complex internal armature composed of elongate sclerites protruding distally; parameres long and slender, with apical setae.

Remarks. Within Cyrtoscydmini , Palaeoscydmaenus is most similar to Australo-Pacific subgenera of Stenichnus : Austrostenichnus Franz, 1971 and Scydmaenilla King, 1864 . In preliminary phylogenetic analysis, all these taxa were resolved as a weakly supported and polytomous branch within Cyrtoscydmini , together with Stenichnus s. str. and some Neotropical (i.e., Parastenichnaphes Franz, 1984 ) and Nearctic (e.g., Brachycepsis Brendel, 1889 ) genera (Jałoszyński, in preparation).

Figures

FIGURES 10 – 12. Holotype male of Palaeoscydmaenus australiensis. Dorsal habitus (10), simplified ventral habitus (11) and original set of labels (12).

FIGURES 13 – 17. Holotype male of Palaeoscydmaenus australiensis. Head in dorsal (13) and ventral (14) views; right antenna in dorsal view (15); prothorax in ventral view (16); and pterothorax in ventral view (17). Abbreviations: ai—asetose impression; ar—anterior ridge; bs—basistipes; cc—procoxal cavity; cd—cardo; cl—clypeus; cs—procoxal socket; fr—frons; gal—galea; gen—gena; gp—gular plate; h—hypostoma; hr—hypostomal ridge; hy—hypomeron; lac—lacinia; lp 2 – 3 — labial palpomere 2 – 3; mcc—mesocoxal cavity; mcp—mesocoxal projection; mcs—mesocoxal socket; md—mandible; mfa—metafurcal arm; mn—mentum; mxp 1 – 4 — maxillary palpomere 1 – 4; nr—neck region; nss—pronotosternal suture; occ—occipital constriction; pfa—profurcal arm; pl—posterior lobe; pre—prepectus; ps—prosternum; smn—submentum; tm—temple; v—vertex; v 2 — mesoventrite; v 3 — metaventrite; vp 2 — mesoventral intercoxal process; vp 3 — metaventral intercoxal process.

FIGURES 18 – 19. Aedeagus of Palaeoscydmaenus australiensis in ventral (18) and lateral (19) views.