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

description: Scydmaenus (Choleropsis) princeps (King)
Heterognathus princeps King, 1864: 98.
Scydmaenus (Cholerus) princeps (King); Csiki, 1819: 73.
Scydmaenus (Cholerus) marwillumbali Franz, 1975: 291. Syn. n.
(Figs 35–40, 55, 64–65, 73, 193)
Type material studied. Lectotype (here designated) (AUSTRALIA). ♂, with labels illustrated in Fig. 193: “K23219” [brownish, handwritten], “ Het / princeps” [brownish, handwritten], “K 197786” [white, printed], “SYNTYPE” [yellow, printed] (AMS). Paralectotype. ♂ (Fig. 36), on separated mounting card, on the same pin under lectotype, same data as for lectotype (AMS).
Specimens studied as high-quality photographs. Holotype of Scydmaenus marwillumbali Franz (AUSTRALIA: NEW SOUTH WALES): ♂ (Fig. 35), with labels illustrated in Fig. 194: “Murwillumbah / N.S.Wales ” [white, handwritten], “ Coll. F. Muir / 801919” [white, printed and handwritten], “ Scydmaenus / marwillumbali / m. / det. H.Franz ” [white, handwritten and printed], “Typus” [red, handwritten] (BM).
Revised diagnosis (based on males). Antennomere 9 only slightly shorter and narrower than 10, with conspicuously deep and abrupt lateral concavity (Fig. 64); antennomere 10 about as long as broad and only slightly impressed (Figs 64–65); aedeagus in dorsal view (Figs 37, 39) with apical margin distinctly concave and as wide as about half of total width of median lobe, lateral subapical lobes prominent, subtriangular, in lateral view (Figs 38, 40) distal region of median lobe strongly broadened, with dorsal margin strongly rounded in proximal half and weakly concave in distal half; metaventrite (Fig. 73) with shallow and diffuse median impression about as broad as half width of metaventrite and filled with short recumbent setae not differing from those on lateral regions.
Redescription. Body of male (Figs 35–36) slightly flattened, elongate and slender, BL 1.75 mm; pigmentation uniformly light to dark brown, appendages (especially antennae and palps) indistinctly lighter (difference best visible in darkest specimens); cuticle moderately glossy, covered with vestiture of yellowish setae.
Head (Fig. 36) in dorsal view transversely subrectangular, broadest at eyes, HL 0.30 mm, HW 0.35 mm; vertex and frons confluent and weakly convex, posterior margin of vertex distinctly concave, arcuate; tempora slightly longer than 3 × length of eye in dorsal view; supraantennal tubercles indistinct; frons over antennal fossae broadly subtrapezoidal and with straight anterior margin. Eyes conspicuously 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 35–36, 55, 64–65) long and slender, AnL 0.95 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 3–4 each nearly 1.5 × as long as broad, 5 twice as long as broad, 6 nearly symmetrical, about as long as broad, 7 and 8 each distinctly transverse and strongly asymmetrical, 9 strongly asymmetrical, with deep and abrupt lateral concavity, 10 slightly broader and indistinctly longer than 9, weakly asymmetrical, with shallow longitudinal (slightly oblique) impression; 11 much shorter than 9 and 10 combined, nearly twice as long as broad, slightly asymmetrical.
Pronotum in dorsal view (Fig. 36) elongate, broadest near anterior third, PL 0.48 mm, PW 0.43 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. 36) oval, broadest slightly in front of middle, EL 0.98 mm, EW 0.68 mm, EI 1.44. 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. 73) with shallow and diffuse median impression about as broad as half width of metaventrite and filled with short recumbent setae not differing from those on lateral regions
Legs (Fig. 36) 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 particularly 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 37–40) elongate but not very slender, AeL 0.28 mm, in dorsal view median lobe broadest near distal third; apical region subtrapezoidal, strongly tapering and with strongly concave apical margin about as wide as 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, flagellum with abruptly broadened and asymmetrically coiled vesicular structure; median lobe in lateral view with distinctly broadened distal portion, its dorsal surface relatively strongly rounded in proximal half and weakly concave in distal half.
Female. Unknown.
Distribution. CE and SE Australia: eastern New South Wales (known only from vicinity of Brisbane and Sydney).
Remarks. The species redescribed by Franz (1975) as S. princeps on p. 288 is in fact S. geniculatus (see Remarks for the latter species).
As many Franz’s names, also S. marwillumbali was based on a misspelled locality, in this case the town Murwillumbah in the Northern Rivers. The antennal modification in S. princeps and S. marwillumbali is identical and unique among all Choleropsis species, and these names are unambiguously synonymous.
Scydmaenus princeps is distinct within Choleropsis and can be easily distinguished from all remaining species by a deep lateral cavity of the antennomere 9. Only S. kroombitanus sp. n. has a somewhat similarly modified antennal club, although the shape of both the antennomere 9 and 10 is different, and in S. princeps the antennomere 5 is strongly elongate, whereas in S. kroombitanus the antennomere 5 is as long as broad.
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 22-24, DOI: 10.11646/zootaxa.5371.1.1, http://zenodo.org/record/10144644