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

description: Scydmaenus (Choleropsis) kroombitanus sp. n.
(Figs 46–50, 57, 68–69, 75)
Type material studied. Holotype (AUSTRALIA: QUEENSLAND), ♂ (Fig. 46), “ Kroombit Tops, 65km SW / Gladstone.Q. 1000-1100m / 22-26 Feb. 1982,Open for. / Monteith,Thompson&Yeates” [white, printed], “ SCYDMAENUS / (CHOLEROPSIS) / kroombitanus m. / P. Jałoszyński, 2023 / HOLOTYPUS” [red, printed] (QM).
Diagnosis (based on male). Antennomeres 9 and 10 of subequal width (Fig. 57); antennomere 9 with deep abrupt lateral concavities both on mesal and outer surface (Fig. 57); antennomere 10 weakly asymmetrical (Figs 68–69); aedeagus in dorsal view (Figs 47, 49) with apical margin with subtriangular emargination and as wide as about half of total width of median lobe, lateral subapical lobes subtriangular, each about as long as broad and projecting strongly laterally, in lateral view (Figs 48, 50) distal region of median lobe weakly broadened, with dorsal margin broadly rounded in proximal 3/4 and concave near apex; metaventrite (Fig. 75) with deep median impression about as broad as half width of metaventrite and filled with setae shorter than those on lateral regions.
Description. Body of male (Fig. 46) slightly flattened, elongate and slender, BL 1.90 mm; pigmentation uniformly moderately dark, appendages indistinctly lighter; cuticle moderately glossy, covered with vestiture of yellowish setae.
Head (Fig. 46) in dorsal view transversely subrectangular, broadest at eyes, HL 0.33 mm, HW 0.43 mm; vertex and frons confluent and weakly convex, posterior margin of vertex distinctly concave, arcuate; tempora as long as 2 × length of eye in dorsal view; supraantennal tubercles indistinct; frons over antennal fossae broadly subtrapezoidal and with straight anterior margin. Eyes small, nearly semicircular in shape, indistinctly emarginate posteriorly and oblique in relation to long axis of head. Punctures on frons and vertex fine, inconspicuous; setae short, sparse, suberect, those on tempora as sparse as those on head dorsum. Genae as sparsely setose as frons and vertex. Anterior (exposed) region of head capsule demarcated from neck region by narrow abrupt impression around occipital constriction, anterior margin of gular plate on neck region accentuated by minute rounded anteriorly-directed projection. Antennae (Figs 46, 57, 68–69) relatively short (compared to other members of Choleropsis), slender, AnL 0.98 mm; three terminal antennomeres forming sharply delimited club; scape about 3 times as long as broad, distinctly broadening distally; pedicel twice as long as broad; antennomeres 3–5 each as long as broad, 6 nearly symmetrical, distinctly transverse, 7 and 8 each strongly transverse and strongly asymmetrical, 9 strongly asymmetrical, about as long as broad, with deep step-wise abrupt concavities both on outer and inner (mesal) surface, 10 indistinctly longer and broader than 9, asymmetrical, with shallow impression; 11 much shorter than 9 and 10 combined, nearly twice as long as broad, slightly asymmetrical.
Pronotum in dorsal view (Fig. 46) elongate, broadest near anterior third, PL 0.53 mm, PW 0.48 mm; anterior and lateral margins confluent and rounded; posterior corners obtuse-angled and blunt; posterior margin nearly straight; base with narrow but distinct posterior marginal carina and with two pairs of small, distinct, sharply marked and relatively deep antebasal pits, each distinctly transverse. Pronotal disc covered with fine and inconspicuous punctures; setae similar to those on frons and vertex, short, moderately dense, suberect. Ventrally prothorax with nearly asetose and impunctate hypomera; basisternal region sparsely covered with short recumbent setae.
Elytra (Fig. 46) oval, broadest slightly in front of middle, EL 1.05 mm, EW 0.78 mm, EI 1.35. Humeral calli weakly elevated; basal impression on each elytron barely marked; basal elytral foveae lacking; apices separately rounded. Punctures fine and inconspicuous; setae similar to those on pronotum. Hind wings not studied.
Metaventrite (Fig. 75) with deep median impression about as broad as half width of metaventrite and filled with setae shorter than those on lateral regions.
Legs (Fig. 46) long and slender; unmodified, except for distal penicillus on mesotibiae and weakly broadened protarsomere 1 and ventral tenent setae distributed on protarsomeres 1–3; protarsi short, tarsomere 1 about 1.5 × as long as broad, 2–4 each about as long as broad, tarsomere 5 3 × as long as broad and slightly shorter than tarsomeres 2–4 combined; mesotarsi long, tarsomere 1 nearly 4 × as long as broad and subequal in length to tarsomeres 2–4 combined, tarsomeres 2–4 each about 1.5 × as long as broad, tarsomere 5 nearly 3 × as long as broad, subequal in length to tarsomeres 3–4 combined; metatarsi as long as mesotarsi, tarsomere 1 about 3. × as long as broad, tarsomeres 2–4 each elongate but decreasing in length distally, tarsomere 5 3 × as long as broad, subequal in length to tarsomeres 3–4 combined.
Aedeagus (Figs 47–50) elongate but not very slender, AeL 0.38 mm, in dorsal view median lobe broadest near distal 2/3; apical region subtrapezoidal, strongly tapering, apical margin with broad subtriangular emargination, as wide as about half of total width of median lobe; lateral subapical lobes prominent and sharply demarcated from median lobe, each subtriangular, about as long as wide, strongly projecting laterally; ostium situated in subapical third of median lobe, flagellum with abruptly broadened and asymmetrical vesicular structure; median lobe in lateral view with slender distal portion demarcated by deep submedian constriction, its dorsal surface strongly rounded in proximal 2/3, distinctly concave near apex.
Female. Unknown.
Distribution. CE Australia: SE Queensland.
Etymology. The adjective kroombitanus is derived from the type locality, Kroombit Tops.
Remarks. Males of Scydmaenus kroombitanus are easy to identify by unusually short antennae with the antennomere 5 not elongate, as in all remaining members of Choleropsis, but as long as broad, and the unique antennal modification.
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 26-29, DOI: 10.11646/zootaxa.5371.1.1, http://zenodo.org/record/10144644