Scydmaenus subglabratus Jałoszyński 2023, sp. n.
Creators: name: Jałoszyński, Paweł
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Scydmaenus
Scydmaenus subglabratus

description: Scydmaenus subglabratus sp. n.
(Figs 163–181)
Type material studied. Holotype (AUSTRALIA: QUEENSLAND): ♁ (Figs 171–173), “ QUEENSLAND (SEQ) / Curtis Farm, Canungra / 25 Feb 1979 / G.B.Monteith ” [white, printed], “Q.M. BERLESATE NO. 79 / 28.03S 153.07E / Rainforest / Stick brushings” [white, printed], “ SCYDMAENUS / (ASCYDMAENUS) / subglabratus m. / P. Jałoszyński, 2023 / HOLOTYPUS ” [red, printed] (QM). Paratypes (7 exx.). QUEENSLAND: 1 ♀, with the same number of QM Berlesate as for holotype, but lacking locality label (QM); 1 ♁, “AUST:QLD:ME: / Nob Creek, Byfield / 27 Apr1979 / G. Monteith ” [white, printed], “QM Berlesate No. 72 / 22.52S 150.37E / Rainforest / Sieved litter” [white, printed] (cPJ); NEW SOUTH WALES: 4 ♀♀, “ 33.33S 151.18E NSW / Pearl Beach, 9 Apr. / 1977 #2413 P.Ward / ex nest Rhyditoponera / chalybaea in rotting / log,wet scler.forest” [white, printed] (ANIC, cPJ); 1 ♀, “Cherry Tree SF. NSW / 15 May 1977 # 2546 / P.Ward, ex nest of / Rhyditoponera cyrus / under stone in dry / rainforest” [white, printed] (ANIC). All paratypes with yellow printed “ PARATYPUS ” labels.
Diagnosis. Body small, below 2 mm in length; dorsum (Fig. 171) nearly glabrous, with very few sparse and short setae; head in dorsal view (Fig. 171) strongly narrowing posteriorly but occipital constriction broader than half width of head; pronotum (Fig. 171) strongly narrowing in posterior half; elytral base (Fig. 171) much wider than pronotal base; in male profemoral tooth minute, short and broad; aedeagus in dorsal view (Fig. 174) with lateral margins in subapical region broadly rounded.
Description. Body in male (Figs 171–173) strongly convex and stout, BL 1.84–1.93 mm; pigmentation uniformly light brown (including appendages); cuticle strongly glossy, covered with barely discernible vestiture of setae slightly lighter than body.
Head (Figs 163–168, 171–173) in dorsal view about as long as broad, somewhat subhexagonal, broadest at eyes, HL 0.34–0.35 mm, HW 0.35–0.36 mm; vertex and frons confluent and weakly convex, posterior margin of vertex nearly straight; tempora about 2.5 × as long as length of eye in dorsal view; supraantennal tubercles indistinct; frons over antennal fossae broadly subtrapezoidal and with nearly straight anterior margin. Eyes small, oval, strongly oblique in relation to long axis of head, not emarginate posteriorly. Punctures on frons and vertex fine, inconspicuous; setae extremely short and nearly recumbent, unevenly distributed, denser on median region of frons and above mesal upper margins of eyes. Genae (Fig. 164) nearly asetose. Anterior (exposed) region of head capsule demarcated from neck region by short abrupt impression around occipital constriction, anterior margin of gular plate on neck region lacking anteriorly-directed projection. Submentum (Figs 164, 168) with prominent submental lobes; hypostomal ridges (Fig. 164) somewhat diffuse. Antennae (Fig. 171) long and slender, AnL 1.33–1.35 mm; three terminal antennomeres forming indistinctly delimited club; scape slightly more than twice as long as broad, distinctly broadening distally; pedicel slightly more than twice as long as broad; antennomere 3 2.5 × as long as broad, 4 1.5 × as long as broad, 5 slightly more than twice as long as broad, 6 1.6 × as long as broad, 7 and 8 each about 1.5 × as long as broad, 9 nearly 2.5 × as long as broad, distinctly broadening distally, 10 1.4 × as long as broad, slightly broadening distally and narrowing in short distal region, 11 much shorter than 9 and 10 combined, about twice as long as broad and nearly symmetrical.
Pronotum in dorsal view (Figs 163, 165, 171–173) about as long as broad, broadest near anterior third, strongly convex anteriorly and flattened in posterior half, PL 0.58 mm, PW 0.59–0.60 mm; anterior and lateral margins together strongly rounded; posterior corners sharply marked, acute and slightly projecting posteriorly; posterior margin nearly straight; posterior marginal carina narrow and distinct. Pronotal disc virtually impunctate and asetose. Ventrally (Fig. 164) prothorax with asetose and impunctate hypomera; basisternal region about as long as procoxal rests, sparsely covered with short recumbent setae, with long and distinctly impressed anterior ‘collar’, and with distinct vestiges of notosternal sutures visible as notches on sides of anterior prothoracic margin; hypomeral ridges diffuse but complete, demarcating narrow inner (adcoxal) region of each hypomeron, anteriorly running along procoxal rests and connecting at middle to form indistinct (i.e., weakly elevated and not sharply marked) anteprocoxal carina demarcating basisternal region posteriorly.
Elytra (Figs 163, 165, 171–173) semioval, broadest near middle, EL 0.93–1.00 mm, EW 0.78–0.80 mm, EI 1.19–1.25. Humeri angulate and projecting anteriorly, but not elevated, basal impressions lacking; apices separately rounded. Elytra virtually impunctate; setae extremely sparse, short, suberect. Hind wings completely reduced.
Mesoventrite (Fig. 169) asetose, metaventrite (Fig. 169) unevenly covered with sparse, short and recumbent setae.
Legs (Figs 164–165, 169, 171–173) moderately long, robust; profemur with minute, inconspicuous distal tooth broader than long; protibia slightly broadened distally; protarsus with barely discernibly broadened proximal half and tarsomeres 1–3 covered ventrally with dense setae, of which only a few have spatulate adhesive tips. Protarsomere 1 indistinctly elongate, 2–4 each about as long as broad, 5 about 2.5 × as long as broad; mesotarsi longer than protarsi, mesotarsomere 1 about 2.5 × as long as broad, tarsomeres 2–4 each weakly elongate, tarsomere 5 about 2.5 × as long as broad; metatarsi indistinctly longer than mesotarsi, metatarsomere 1 2.5 × as long as broad, tarsomeres 2–4 each about 1.5 × as long as broad, tarsomere 5 about 2.5 × as long as broad.
Aedeagus showing small variability, illustrated specimens come from Curtis Farm (Figs 174–177) and Nob Creek (Figs 178–181); elongate and moderately slender, AeL 0.50 mm, in dorsal view median lobe broadest near base, narrowing distally but slightly broadening in subapical region, where lateral margins are broadly rounded; apex rounded and with distinct median notch, with barely discernible, extremely short lateral groups of distal setae; flagellum broadened in proximal region to form three poorly discernible consecutive symmetrical chambers; ostium situated in distal third of median lobe, far from its apex.
Female. Externally differs from male in profemora lacking distal teeth. BL 1.83–1.95 mm; HL 0.35–0.38 mm, HW 0.31–0.33 mm, AnL 0.95–1.03 mm; PL 0.50–0.55 mm, PW 0.41–0.48 mm; EL 0.98–1.05 mm, EW 0.70–0.75 mm, EI 1.37–1.45.
Etymology. The specific adjective subglabratus refers to the nearly asetose dorsum of this Scydmaenus.
Distribution. Known only from SE Australia: CE and SE Queensland and CE and NE New South Wales.
Remarks. The nearly glabrous dorsum, and the shapes of the head, pronotum and elytra are not unique for this species. Three females from Queensland were seen, each representing one undescribed species, which share these characters with S. subglabratus, but clearly differ in proportions of antennomeres (in all of them at least some antennomeres are much shorter than in S. subglabratus). For this reason, shapes and measurements of all body parts, as well as the aedeagus must be carefully examined to identify newly collected specimens with a similarly glabrous dorsum.
description: Published as part of Jałoszyński, Paweł, 2023, Scydmaenus Latreille of Australia: Revision of species in subgenera Choleropsis Franz, Kingius Franz, Mascarensia Franz, Parallomicrus Franz, Scottiscydmaenus Franz, and description of Ascydmaenus subgen. n. (Coleoptera, Staphylinidae, Scydmaeninae), pp. 1-75 in Zootaxa 5371 (1) on pages 64-68, DOI: 10.11646/zootaxa.5371.1.1, http://zenodo.org/record/10144644