Euconnus advolans
Creators: name: Jałoszyński, Paweł
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Euconnus
Euconnus advolans

description: Euconnus (s. str.) advolans (Nietner)
(Figs 24, 43–44)
Scydmaenus advolans Nietner, 1856: 549.
Scydmaenus (Scydmaenus) advolans Nietner; Csiki, 1919: 78.
Scydmaenus quinque foveolatus Motschulsky, 1863: 427. Syn. nov.
Euconnus (Euconnus) quinquefoveolatus (Motschulsky); Csiki, 1919: 51.
Type material. Lectotype (here designated): ♂, three labels: “ Ceylon / Nietner..s” (white, printed and handwritten, text in black frame], QR code label with collection number 8189, and newly added “ EUCONNUS / (s. str.) / advolans (Nietner, 1856) / LECTOTYPUS / P. Jałoszyński, 2025 ” (MIZ). Paralectotypes (3 exx.): 3 ♀♀, each with white printed copies of original label, and with identification labels with “PARALECTOTYPUS” (MIZ).
Revised diagnosis. Vertex in lateral view weakly bulging posterodorsad and with dense thick bristles; eyes conspicuously large, in lateral view longer than tempora; antennal clubs distinctly tetramerous and longer than remaining flagellomeres combined; pronotum widest slightly behind middle, strongly narrowing anteriorly and weakly posteriorly, with five antebasal pits connected by shallow transverse groove; legs of male lacking any modifications; aedeagus in ventral view pear-shaped, broadest in sub-basal region, then narrowing distally but broadened in subapical region, apex subtrapezoidal with deep and narrow median notch; membranous area conspicuously small and circular, situated in sub-basal ventral region; endophallus asymmetrical, with subapical V-shaped structure; parameres not reaching apex of median lobe.
Redescription. Body of male (Fig. 24) moderately slender, strongly convex, moderately dark brown; setae distinctly lighter than cuticle; BL 1.38 mm.
Head broadest across large and coarsely faceted eyes strongly projecting from head silhouette, HL 0.25 mm, HW 0.28 mm; frontal and anterior vertexal regions confluent, weakly convex, vertex weakly bulging posterodorsad; supraantennal tubercles weakly elevated. Punctures on frons and vertex fine and inconspicuous; setae sparse, short and weakly suberect; tempora and vertex with dense and long bristles directed posteriorly. Antennae slender, with sharply delimited tetramerous clubs longer than remaining flagellomeres combined, AnL 0.65 mm; antennomere 1–2 each strongly elongate, 3–10 each weakly transverse, 11 as broad as 10, distinctly shorter than 9–10 combined, about 1.5 times as long as broad.
Pronotum semielliptical, broadest slightly behind middle; PL 0.38 mm, PW 0.35 mm; anterior margin strongly rounded and confluent with lateral margins, which are rounded and anteriorly more strongly convergent than posteriorly; posterior corners obtuse-angled and blunt; posterior margin straight; base with two lateral pairs of small round pits and similarly small median pit, all connected by shallow transverse groove. Punctures on pronotal disc similar to those on frons and vertex, inconspicuous; setae moderately long, moderately dense and suberect, lateral margins with dense and long bristles.
Elytra together oval, broadest slightly anterior to middle; EL 0.75 mm, EW 0.55 mm, EI 1.36; humeral calli distinctly elevated, basal impressions shallow but distinct; elytral apices separately rounded. Punctures and setae similar to those on median region of pronotal disc.
Legs moderately long, slender, lacking any peculiar modifications.
Aedeagus (Figs 43–44) stout and in lateral view weakly curved;AeL 0.20 mm; median lobe in ventral view pear-shaped, broadest in sub-basal region, then narrowing distally but broadened in subapical region, apex subtrapezoidal with deep and narrow median notch; membranous area conspicuously small and circular, situated in sub-basal ventral region; endophallus asymmetrical, with subapical V-shaped structure; parameres slender and in ventral view strongly curved, not reaching apex of median lobe, each with two apical setae of unequal lengths.
Female. Externally similar to male, except for slightly smaller eyes, in lateral view about as long as tempora. BL 1.35–1.48 mm; HL 0.25 mm, HW 0.28–0.30 mm, AnL 0.58–0.63 mm; PL 0.35–0.43 mm, PW 0.35–0.40 mm; EL 0.75–0.80 mm, EW 0.55–0.60 mm, EI 1.29–1.39.
Distribution. Sri Lanka, near Colombo.
Remarks. The type series of Scydmaenus advolans is composed of four specimens (originally mounted on one card), of which only one is a male. The three females seem to be conspecific with the male.All specimens agree with the original description, except for one important difference. Nietner stated that the pronotum is “4-foveolatus”, whereas the specimens have a distinct median antebasal pit and two pairs of lateral pits. Franz (1982) did not mention this name.
Specimens from Nietner coll. belong in Euconnus (s. str.), and the aedeagus extracted from the only male is identical with that illustrated by Franz, 1982: figs 168A, B for E. quinquefoveolatus (Motschulsky) (as the name implies, it has five antebasal pronotal foveae). However, it should be noted that Franz examined a female type specimen of E. quinquefoveolatus, and that his aedeagus drawing is based on a newly collected material, that has been compared with that female. Without re-examination of the type material (deposited in Moscow), the identity of males studied by Franz is not certain, so the present placing of E. quinquefoveolatus as a junior synonym of E. advolans will require verification. The only male from the Nietner coll. (Fig. 24) is designated here as the lectotype of Scydmaenus advolans.
This species seems to differ from all SE Asian congeners in the structure of the aedeagus. However, aedeagi of some species have been inadequately illustrated, and most world species require revision.
description: Published as part of Jałoszyński, Paweł, 2025, John Nietner collection of Sri Lankan Scydmaeninae (Coleoptera, Staphylinidae), pp. 79-109 in Zootaxa 5633 (1) on pages 94-96, DOI: 10.11646/zootaxa.5633.1.4, http://zenodo.org/record/15372835