Scydmaenilla (Scydmaenilla) pusilla King

Jałoszyński, Paweł, 2013, Revision of subgenera of Stenichnus Thomson, with review of Australo-Pacific species (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 3630 (1), pp. 39-79 : 69-70

Scydmaenilla (Scydmaenilla) pusilla King , stat. rest.

( Figs. 74–83 )

Scydmaenilla pusilla King, 1864: 93 .

Stenichnus (Scydmaenilla) pusillus (King) ; Franz, 1975: 136 (redescription based on a misidentified specimen, not S. pusilla !).

Lectotype designation. King (1864) described S. pusilla on the basis of two syntype specimens. Although the female ( Fig. 75 ) is better preserved, the species diagnosis is based primarily on the unique aedeagus, and therefore the male ( Fig. 74 ) is here designated a lectotype to ensure the stability of nomenclature and to provide a unique name-bearing type for Scydmaenilla pusilla . The syntypes were mounted on one card ( Fig. 76 ); they were remounted on separate cards and pins during the present study and the male lectotype retained the original set of labels ( Fig. 77 ), while the female paralectotype was provided with copies.

Material studied. Lectotype (here designated) 3: three labels ( Fig. 77 ): " Scydmaenilla / pusilla / 160" [yellowish, handwritten in faded black or blue], "1523/36" [yellowish, handwritten in faded black or blue], and a more recent label with a museum collection number "K 197803" [white, printed] (AMS); paralectotype, Ƥ: labels as for lectotype (AMS)

Diagnosis. Body distinctly flattened, length ca. 1 mm; elytra moderately slender, EI nearly 1.5; antennal club symmetrical; metatibiae with sub-apical setal brushes; lateral metaventral carinae absent; short median longitudinal groove on posterior pronotal collar absent; lateral marginal pronotal carinae well-marked; aedeagus strongly elongate, with broadened apex.

Redescription. Body of male ( Fig. 74 ) flattened, elongate and moderately slender, with long appendages, BL 1.06 mm; glossy, uniformly light brown with appendages barely lighter than body; vestiture yellowish.

Head ( Fig. 79 ) approximately subtriangular, broadest at eyes, HL 0.20 mm, HW 0.23 mm; tempora distinctly shorter than eyes; vertex distinctly transverse and weakly, evenly convex, anteriorly confluent with frons; frons convex; supraantennal tubercles barely marked; eyes moderately large and convex, bean-shaped and nearly transverse in relation to the long axis of head. Punctures on head dorsum fine and sparse, inconspicuous; setae short, sparse, suberect. Antennae ( Fig. 74 ) slender, with distinctly enlarged club composed of antennomeres IX–XI, AnL 0.43 mm; antennomeres I–VI elongate, VII–VIII each about as long as broad; IX–X distinctly transverse, XI 1.6 × as long as broad.

Pronotum ( Fig. 74 ) in dorsal view with oval anterior part and short posterior collar, broadest near anterior fourth, PL 0.29 mm, PW 0.25 mm; anterior and lateral margins confluent and rounded; sides in posterior third indistinctly constricted demarcating short posterior part; hind pronotal corners blunt and obtuse; posterior margin distinctly arcuate; base of pronotum with narrow and deep ante-basal transverse groove connected laterally to shallow but distinct triangular impressions; lateral marginal carinae well-developed in posterior half of pronotum. Punctures on pronotal disc very fine and inconspicuous, those behind ante-basal groove dense and distinct but shallow and with diffused margins; setae moderately long, sparse and suberect.

Elytra ( Fig. 74 ) oval and only slightly more convex than pronotum, broadest distinctly anterior to middle, EL 0.60 mm, EW 0.41 mm, EI 1.45; humeral calli distinct, developed as elongate protuberances; elytral apices separately rounded. Punctures on elytral disc forming indistinct longitudinal rows, well-visible only near distinctly raised suture in anterior 2/3 of elytra, laterally and posteriorly punctures gradually reducing in diameters and depth; setae moderately long and sparse, suberect. Hind wings not studied.

Legs ( Fig. 74 ) long and slender; all tibiae straight or nearly straight, metatibiae with sub-apical setal brushes.

Aedeagus ( Figs. 82–83 ) strongly elongate, slender, AeL 0.25 mm, in the only known male with partly damaged apex; apical part broadened; internal armature darkly sclerotized, with a pair of subtriangular sclerites; parameres long and slender, each with one apical seta and several setae distributed latero-ventrally along distal 2/3 of paramere; bases of parameres surrounding basal orifice darkly sclerotized.

Female ( Figs. 75 , 78–81 ). Externally similar to male, differs slightly in measurements: BL 1.08 mm; HL 0.18 mm, HW 0.23 mm; AnL 0.45 mm; PL 0.28 mm, PW 0.25 mm; EL 0.63 mm, EW 0.43 mm, EI 0.47.

Distribution. Southeastern Australia: eastern New South Wales.

Remarks. According to the original description (King 1864) the syntypes were collected in Paramatta (today a suburb of Sydney).

The body silhouette of S. pusilla in dorsal view is highly similar to that of S. thompsoniana . These two species share similar proportions of body parts (including the pronotal and elytral indexes), but S. pusilla can be easily distinguished on the basis of a flattened body (strongly convex in S. thompsoniana ), much more distinct lateral marginal carinae of pronotum, less distinct elytral punctation, a raised elytral suture and a symmetrical antennomere X (slightly asymmetrical in S. thompsoniana ).

Figures

FIGURES 74 – 77. Scydmaenilla pusilla King. Dorsal habitus of lectotype male (74) and paralectotype female (75), original preparation before remounting (76), and original set of labels of syntypes, currently pinned under lectotype (77).

FIGURES 78 – 83. Scydmaenilla pusilla King, paralectotype female (78 – 81) and lectotype male (82 – 83). Venter (78), head in ventral view (79), prothorax in ventral view (80), pterothorax in ventral view (81), aedeagus in ventral (82) and lateral (83) views. Abbreviations: ai, asetose impression of mesoventrite; ar, anterior ridge; bs, basisternal part of prosternum; bst, basistipes; cd, cerdo; gal, galea; gp, gular plate; gs, gular suture; h, hypostoma; hr, hypostomal ridge; hy, hypomeron; lac, lacinia; lp, labial palp; lpi, lateral prosternal impression; lss, lateral suture of submentum; mcp, mesocoxal projection; md, mandible; mn, mentum; mscc, mesocoxal cavity; msvp, mesoventral intercoxal process; mtap, metaventral anterior process; mtfa, metafurcal arm; mtvp, metaventral intercoxal process; nss, notosternal suture; occ, occipital constriction; pcc, procoxal cavity; pcs, procoxal socket; pmn, prementum; pre, prepectus; smn, submentum; tm, temple; v 3, metaventrite.