Microscydmus (Scydmomicrus) styxianus, Jałoszyński, Paweł, 2014

Jałoszyński, Paweł, 2014, The smallest Cyrtoscydmini of Australia: revision of Microscydmus Saulcy & Croissandeau and Penicillidmus gen. n. (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 3774 (1), pp. 1-30 : 22-23

Microscydmus (Scydmomicrus) styxianus sp. n.

( Figs. 24 , 33 , 56 , 62 )

Material studied. Holotype: ♂: three labels: " 30.44S 152.05E NSW / Styx River SF., / Cedar Pit Flor. Res. / 42km SE Wollomombi / 935m, 10 June 1993 / D.S. Chandler" [white, printed], "Berlesate ANIC 1638 / old subtr. closed forest / mixed litter" [white, printed], " MICROSCYDMUS / (SCYDMOMICRUS) / styxianus m. / det. P. Jałoszyński, 2013 / HOLOTYPUS " [red, printed] ( ANIC).

Diagnosis. Male: body uniformly light brown; frons subtriangular with tiny antero-median projection; punctures on head fine but distinct, clearly more distinct than those on pronotum; BL <0.60 mm; pronotum as broad as head, with ante-basal transverse groove; EI <1.50; aedeagus with distinct internal armature containing a pair of lightly sclerotized strongly elongate sub-median sclerites surrounded at the level of basal foramen by a pair of darkly sclerotized loops and with subapical lateral groups of densely assembled microscopic needle-like structures. Females and their diagnostic characters unknown.

Description. Body of male ( Fig. 24 ) moderately convex, strongly elongate and slender, with moderately long appendages, BL 0.587 mm; cuticle glossy; body uniformly light brown with slightly lighter appendages; vestiture yellowish.

Head ( Fig. 33 ) subtrapezoidal, broadest at eyes, HL 0.100 mm, HW 0.150 mm; tempora much shorter than eyes, strongly convergent postero-mesally; vertex weakly convex; frons subtriangular with small antero-median projection. Eyes large but moderately projecting laterally from the head silhouette, coarsely faceted. Punctures on head dorsum sparse and small but distinct; setae short, sparse and suberect. Antennae slender, AnL 0.250 mm; antennomeres I–II elongate, III–X transverse; XI as long as broad.

Pronotum ( Fig. 33 ) in dorsal view oval, broadest near anterior third, PL 0.137 mm, PW 0.150 mm; anterior and lateral margins rounded; posterior margin shallowly bisinuate; base of pronotum with two pairs of small and shallow pits, internal pair connected by transverse impression. Punctures on pronotal disc fine and inconspicuous; setae sparse, thin, short and suberect.

Elytra oval, slightly more convex than pronotum, broadest near middle, EL 0.350 mm, EW 0.237 mm, EI 1.474; basal impressions short; elytral apices separately rounded. Punctures on elytral disc slightly more distinct than those on pronotum but still fine and unremarkable; setae short, sparse and suberect. Hind wings well developed, about twice as long as elytra.

Legs moderately long and slender, without modifications.

Aedeagus ( Fig. 56 ) large, AeL 0.13 mm; moderately slender, with distinct internal armature containing several well-defined components: a pair of lightly sclerotized strongly elongate sub-median sclerites extending from base to subapical region of median lobe, sub-basally located pair of dark lateral sclerites forming elongate loops, and subapical lateral groups of densely assembled microscopic needle-like structures; each paramere with long apical seta.

Female. Unknown.

Distribution ( Fig. 62 e). E Australia (NE New South Wales).

Etymology. Locotypical, after the Styx River, near which the holotype was collected.

Remarks. Microscydmus styxianus is the most slender Australian species; it can be easily identified on the basis of the very short pronotum in relation to the elytra. The ratio EL/PL for M. styxianus is 2.545, while for all remaining species it equals 1.857–2.400.

Figures

FIGURES 20 – 28. Dorsal habitus of holotypes. Microscydmus (Scydmomicrus) australiensis Franz, female (20); M. (Sc.) nasicornis Franz, female (21); M. (Sc.) capitiseboraci sp. n., male (22); M. (Sc.) queenslandicus sp. n., male (23); M. (Sc.) styxianus sp. n., male (24); M. (Sc.) edithensis sp. n., male (25); M. (Sc.) tooloomensis sp. n., male (26); Penicillidmus masseyensis sp. n., male (27); P. unicolor sp. n., male (28).

FIGURES 29 – 37. Body silhouette of holotypes. Microscydmus (Scydmomicrus) australiensis Franz, female (29); M. (Sc.) nasicornis Franz, female (30); M. (Sc.) capitiseboraci sp. n., male (31); M. (Sc.) queenslandicus sp. n., male (32); M. (Sc.) styxianus sp. n., male (33); M. (Sc.) edithensis sp. n., male (34); M. (Sc.) tooloomensis sp. n., male (35); Penicillidmus masseyensis sp. n., male (36); P. unicolor sp. n., male (37).

FIGURES 54 – 61. Aedeagi in ventral views. M. (Sc.) capitiseboraci sp. n. (54); M. (Sc.) queenslandicus sp. n. (55); M. (Sc.) styxianus sp. n. (56); M. (Sc.) edithensis sp. n. (57); M. (Sc.) tooloomensis sp. n. (58 – 59); Penicillidmus masseyensis sp. n. (60); P. unicolor sp. n. (61).

FIGURES 62 – 63. Distribution of Microscydmus (Scydmomicrus subgen. n.) (62) and Penicillidmus gen. n. (63). Microscydmus (Scydmomicrus) australiensis Franz (62 a); M. (Sc.) nasicornis Franz (62 b); M. (Sc.) capitiseboraci sp. n. (2 c); M. (Sc.) queenslandicus sp. n. (62 d); M. (Sc.) styxianus sp. n. (62 e); M. (Sc.) edithensis sp. n. (62 f); M. (Sc.) tooloomensis sp. n. (62 g); Microscydmus (Sc.) sp. (62 h); Penicillidmus masseyensis sp. n. (63 a); P. unicolor sp. n. (63 b); Penicillidmus sp. (63 c).