Austrostenichnus Franz

Jałoszyński, Paweł, 2013, Revision of subgenera of Stenichnus Thomson, with review of Australo-Pacific species (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 3630 (1), pp. 39-79 : 54-55

Genus Austrostenichnus Franz , stat. nov.

Austrostenichnus Franz, 1971: 45 (as subgenus of Stenichnus ). Type species: Stenichnus caledonicus Franz, 1971 (monotypy).

Revised diagnosis. Eyes located posteriorly; occipital constriction nearly as broad as vertex; fronto-clypeal groove absent; mandibles subtriangular, with broad and abruptly demarcated basal part and subapical tooth on mesal margin; submentum trapezoidal, completely demarcated from hypostomae by lateral sutures; hypostomae elongate and demarcated from genae by complete hypostomal ridges; posterior tentorial pits hidden in deep groove separating submentum from gular plate; antennae gradually thickening distally; pronotum with one pair of lateral ante-basal pits connected by transverse groove, without lateral marginal carinae; prosternum with moderately narrow basisternal part demarcated from procoxal cavities by carina, procoxal cavities not separated in middle; hypomera not demarcated from pronotum; mesoventrite with asetose impressions not separated in middle and setose lateral impressions broadly separated in middle and broadly separated from mesocoxal cavities; mesoventral intercoxal process broad and nearly flat, posteriorly fused with metaventrite; mesocoxal projections with posterior lobes; metaventrite without metaventral anterior process, with short and broad metaventral intercoxal projection bearing median notch; aedeagus with free parameres.

Redescription. Body ( Figs. 52–53 ) strongly convex, strongly elongate and slender, with long appendages, cuticle glossy, distinctly setose.

Head ( Figs. 57–59 ) subtriangular, broadest at posteriorly located eyes; neck region ( Fig. 58 ; nr) short and subcylindrical, only slightly broadened in middle; occipital constriction ( Figs. 58–59 ; occ) in the narrowest place as wide as vertex; tempora ( Fig. 58 ; tm) much shorter than eyes; vertex ( Fig. 58 ; vt) and frons ( Fig. 58 ; fr) between eyes confluent and convex, frons between antennal insertions flattened; fronto-clypeal groove absent.

Labrum ( Figs. 58–59 ; lb) transverse with rounded sides and anterior margin. Mandibles ( Fig. 58 ; md) symmetrical, each with broad basal part and abruptly demarcated, moderately slender distal part, without noticeable prostheca, mesal margin with median tooth.

Each maxilla with elongate galea and lacinia ( Fig. 59 ; gal, lac) and long maxillary palp ( Fig. 59 ; mxp) composed of minute palpomere I, strongly elongate and broadening distally palpomere II, long and pedunculate palpomere III broadest near middle and slender, strongly elongate subconical and pointed palpomere IV.

Labium with trapezoidal submentum ( Fig. 59 ; smn) posteriorly demarcated from gular plate ( Fig. 59 ; gp) by deep transverse groove in which posterior tentorial pits are hidden, laterally demarcated from hypostomae ( Fig. 59 ; h) by complete lateral sutures ( Fig. 59 ; lss); mentum subtrapezoidal ( Fig. 59 ; mn); prementum short with narrowly separated, small 3-segmented labial palps ( Fig. 52 ; lp). Laterally mouthparts demarcated from genae by long and complete hypostomal ridges ( Fig. 59 ; hr).

Gular plate ( Fig. 59 ; gp) large and trapezoidal in shape, with distinct gular sutures ( Fig. 59 ; gs).

Antennae ( Figs. 52–53 ) gradually thickening towards apices, slender.

Prothorax ( Figs. 52–53 , 57, 60 ) in dorsal view with rounded anterior and lateral margins of pronotum, at base with transverse groove connecting one pair of lateral ante-basal foveae, without lateral marginal carinae or edges; hypomera ( Fig. 60 ; hy) not demarcated from notum. Prosternum ( Fig. 60 ) with moderately short basisternal part ( Fig. 60 ; bs); procoxal cavities ( Fig. 60 ; pcc) with anterior marginal carina and not separated in middle; procoxal sockets ( Fig. 60 ; pcs) closed by lateral expansion of sternum; notosternal sutures ( Fig. 60 ; nss) complete.

Mesoventrite ( Figs. 57, 61 ) with narrow anterior ridge ( Fig. 61 ; ar), lateral asetose impressions ( Fig. 61 ; ai) not separated in middle and large lateral setose impressions ( Fig. 61 ; si) broadly separated in middle and broadly separated from mesocoxal cavities ( Fig. 61 ; mscc); mesocoxal projection ( Fig. 61 ; mcp) without carina and with posterior lobe ( Fig. 61 ; pl) bearing dense setae along posterior margin; mesoventral intercoxal process ( Fig. 61 ; msvp) relatively broad and nearly flat, posteriorly fused to metaventrite

Metaventrite ( Figs. 57, 61 ) broader than long, without metaventral anterior process; metaventral intercoxal process ( Fig. 61 ; mtvp) broad and short, with distinct median notch.

Elytra ( Figs. 52–53 ) oval, with well-marked humeral calli; each elytron with one rudimentary basal fovea barely noticeable in dry-mounted specimens. Hind wings well-developed.

Legs ( Figs. 52–53 ) long and slender; femora clavate, tibiae nearly straight, tarsi strongly elongate.

Abdominal sternites VII and VIII separated by indistinct suture.

Aedeagus ( Figs. 55–56 ) with complex and symmetrical internal armature composed of elongate, moderately darkly sclerotized structures; parameres free and slender, with apical setae.

Distribution and composition. Three species were described in Stenichnus (Austrostenichnus) , one from New Caledonia and two from New Zealand. However, the species from New Zealand clearly represent a separate genus described in a further part of this paper, and Austrostenichnus , elevated here to the genus rank, comprises only A. caledonicus known to occur in southern New Caledonia.

Remarks. Austrostenichnus differs from Stenichnus in the lack of fronto-clypeal groove; different shape of mandibles; different sculpture of the basal part of pronotum; lack of prosternal carina separating procoxal cavities; the mesoventrite bearing asetose impressions confluent in middle and broadly separated setose impressions; the shape of mesoventral intercoxal process; lack of carina on mesocoxal projection; lack of metaventral anterior process; and the elytral base with only one rudimentary fovea (major differences are compiled in Table 1 ). Such a large number of significant differences justifies the placement of Austrostenichnus as a separate genus.

Although in the available specimens it was not possible to examine details of the prementum, the approximate bases of labial palps suggest that labial discs, characteristic of Stenichnus , are absent.

Figures

FIGURES 52 – 56. Austrostenichnus caledonicus Franz, holotype male (52, 54 – 56) and non-type female (53). Dorsal (52) and lateral (53) habitus, set of original labels of holotype (54), aedeagus of holotype in ventral (55) and lateral (56) views.

FIGURES 57 – 61. Austrostenichnus caledonicus Franz; paratype female. Venter (57), head in dorsal (58) and ventral (59) views, prothorax in ventral view (60) and pterothorax in ventral view (61). Abbreviations: aest 2, mesanepisternum; ai, asetose impression of mesoventrite; ar, anterior ridge; bs, basisternal part of prosternum; bst, basistipes; cd, cardo; cl, clypeus; cx 3, metacoxa; fr, frons; gal, galea; gp, gular plate; gs, gular suture; h, hypostoma; hr, hypostomal ridge; hy, hypomeron; lac, lacinia; lb, labrum; lp, labial palp; lss, lateral suture of submentum; mcp, mecocoxal projection; md, mandible; mn, mentum; mscc, mesocoxal cavity; msvp, mesoventral intercoxal process; mtfa, matefurcal arm; mtvp, metaventral intercoxal process; mxp, maxillary palp; nr, neck region; nss, notosternal suture; occ, occipital constriction; pcc, procoxal cavity; pcs, procoxal socket; pl, posterior lobe of mecocoxal projection; pre, prepectus; si, setose impression of mesoventrite; smn, submentum; tm, temple; v 3, metaventrite; vt, vertex.