Euconnus ceylanicus Nietner 2025, stat. rev.
Creators: name: Jałoszyński, Paweł
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Euconnus
Euconnus ceylanicus

description: Euconnus (incertae sedis) ceylanicus Nietner, stat. rev.
(Figs 32, 57–58)
Scydmaenus Ceylanicus Nietner, 1856: 545.
Scydmaenus (Scydmaenus) Ceylanicus Nietner; Csiki, 1919: 79.
Eumicrus crassicornis Motschulsky, 1858: 29. Placed as junior synonym in Csiki, 1919: 79.
Type material. Lectotype (here designated): ♂, three labels: “ Ceylon / Nietner..s” (white, printed and handwritten, text in black frame], QR code label with collection number 8194, and newly added “ EUCONNUS / (s. str.) / ceylanicus (Nietner, 1856) / LECTOTYPUS / P. Jałoszyński, 2025 ” (MIZ).
Revised diagnosis. Vertex not bulging posterodorsad and lacking bristles; eyes small, in lateral view half as long as tempora; antennal clubs tetramerous and longer than remaining flagellomeres combined, with antennomere 8 asymmetrical, projecting mesad; pronotum widest near middle, without antebasal pits; protarsomere 1 with elongate subtriangular anteromedian tooth on ventral surface; aedeagus in ventral view broadest slightly distad middle, with delimited apical region with rounded apical margin, endophallus with long median subtriangular sclerite flanked by groups of smaller asymmetrical sclerites, parameral apices not reaching apex of median lobe.
Redescription. Body of male (Fig. 32) strongly elongate, slender and strongly flattened, light brown; setae distinctly lighter than cuticle; BL 1.23 mm.
Head broadest across eyes, HL 0.28 mm, HW 0.33 mm; frontal and anterior vertexal regions confluent, flat at middle, vertexal region not bulging posterodorsad; supraantennal tubercles barely marked; eyes small, in lateral view half as long as tempora. Punctures on frons and vertex fine and inconspicuous; setae sparse, short and weakly suberect; tempora and vertex without bristles.Antennae slender, with tetramerous clubs, AnL 0.55 mm; antennomere 1–2 each strongly elongate, 3–7 each about as long as broad, 8 slightly transverse and distinctly asymmetrical, projecting mesad, 9 and 10 each weakly transverse and symmetrical, 11 slightly wider than 10, nearly as long as 9–10 combined, about 1.6 times as long as broad.
Pronotum oval, broadest near middle; PL 0.33 mm, PW 0.30 mm; anterior margin weakly arcuate, anterior corners poorly marked, obtuse-angled and blunt; lateral margins moderately strongly rounded; posterior corners weakly obtuse-angled and blunt; posterior margin weakly arcuate; base lacking pits and grooves. Punctures on pronotal disc similar to those on frons and vertex, inconspicuous; setae moderately long, moderately dense and suberect, lateral margins with bristles only near posterior corners.
Elytra together oval, broadest near middle; EL 0.68 mm, EW 0.43 mm, EI 1.59; humeral calli weakly elevated, basal impressions shallow and small, developed only at humeral calli; elytral apices separately rounded. Punctures and setae similar to those on median region of pronotal disc.
Legs moderately long, slender; protarsomere 1 with elongate subtriangular anteromedian tooth on ventral surface. Aedeagus (Figs 57–58) stout; AeL 0.18 mm; in ventral view broadest slightly distad middle, with subtriangular distal region abruptly demarcated from basal capsule, apical margin rounded; dorsal plate straight, not bent or curved dorsad, endophallus with long median subtriangular sclerite flanked by groups of smaller asymmetrical sclerites, parameres slender, in ventral view largely straight, parameral apices not reaching apex of median lobe, each paramere with 4 apical setae of various lengths.
Female. Unknown.
Distribution. Sri Lanka, near Colombo.
Remarks. Nietner (1856) stated that he collected S. ceylanicus from spider webs, and he did not specify the number of specimens. Therefore, the only available specimen (a male) must be treated as a syntype, and is here designated as the lectotype. Franz (1982) does not mention this species.
The type specimen clearly belongs in Stenichnini, and can be placed in Euconnus. Franz (1982) placed many very similar species in the E. nietnerianus group, as incertae sedis within Euconnus. I have examined most species that belong in this potentially distinct group and compared them with the lectotype of E. ceylanicus, to make sure that it is different from all of the Franz’s species. They all show some characters similar to the subgenus Tetramelus, and this group is a candidate for a separate subgenus endemic to Sri Lanka.
Eumicrus crassicornis Motschulsky was placed as a junior synonym of E. ceylanicus by Csiki (1919). However, Csiki did not examine any type specimens and this synonymy requires verification.
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 103-106, DOI: 10.11646/zootaxa.5633.1.4, http://zenodo.org/record/15372835