Scydmaenus pselaphoides Nietner
Creators: name: Jałoszyński, Paweł
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Scydmaenus
Scydmaenus pselaphoides

description: Scydmaenus (s. str.) pselaphoides Nietner
(Figs 21, 37–38)
Scydmaenus pselaphoides Nietner, 1856: 547.
Scydmaenus (Scydmaenus) pselaphoides Nietner; Franz, 1982: 131.
Scydmaenus (Scydmaenus) singaporanus Franz, 1985a: 125. Syn. nov.
Type material. Lectotype (here designated): ♂, three labels: “ Ceylon / Nietner..s” (white, printed and handwritten, text in black frame], QR code label with collection number 8204, and newly added “ SCYDMAENUS / (s. str.) / pselaphoides Nietner, 1856 / LECTOTYPUS / P. Jałoszyński, 2025 ” (MIZ). Paralectotypes (5 exx.): 5 ♀♀, three and two on two pins, each pin with original label “ Ceylon / Nietner..s” (white, printed and handwritten, text in black frame], QR code label with collection numbers 8198 and 8202, respectively, and identification labels with “PARALECTOTYPUS” {but see Remarks for uncertain identity} (MIZ).
Revised diagnosis. Head conspicuously small, much narrower than pronotum; head and pronotum with fine, inconspicuous punctures, while those on elytra dense and distinct; aedeagus in dorsal view narrowing from base to subapical region and then strongly broadening to form rounded lateraloapical lobes clearly separated distomedially, in lateral view median lobe weakly and almost evenly curved.
Redescription. Body of male (Fig. 21) strongly elongate and strongly convex, moderately dark brown; setae distinctly lighter than cuticle; BL 1.93 mm.
Head broadest across large and finely faceted eyes weakly projecting from head silhouette, HL 0.33 mm, HW 0.36 mm; frontal and vertexal regions confluent, weakly convex, vertex not impressed posteromedially; supraantennal tubercles weakly elevated. Punctures on frons and vertex fine and inconspicuous; setae sparse, short and weakly suberect. Antennae slender, with slender trimerous clubs, AnL 1.00 mm; antennomere 1–6 each strongly elongate, 7 about as long as broad and slightly asymmetrical, 8 distinctly transverse and asymmetrical, 9 and 10 each slightly elongate, 11 slightly broader than 10, indistinctly shorter than 9–10 combined, about twice as long as broad.
Pronotum oval, broadest slightly behind anterior third; PL 0.58 mm, PW 0.53 mm; anterior margin strongly rounded and confluent with lateral margins, which are anteriorly strongly rounded and indistinctly angulate at widest site of pronotum and posteriorly nearly straight; posterior corners obtuse-angled and blunt; posterior margin weakly arcuate; base with two lateral pairs of small round pits. Punctures on pronotal disc similar to those on frons and vertex; setae moderately long, moderately dense and suberect to erect.
Elytra together oval, broadest slightly anterior to middle; EL 1.03 mm, EW 0.80 mm, EI 1.28; humeral calli distinctly elevated, basal impressions shallow but distinct, adscutellar elytral margins elevated to form rounded ridges flanking scutellum and forming V-shaped structure; elytral apices separately rounded. Punctures much larger, deeper and denser than those on pronotum, slightly unevenly distributed and separated by spaces subequal to their diameters; setae moderately long and dense, suberect to erect.
Legs long and slender, protarsi broadest proximally and distinctly narrowing distad.
Metathoracic anapleural sulcus complete.
Aedeagus (Figs 37–38) strongly elongate; AeL 0.58 mm; median lobe in dorsal view narrowing from base to subapical region and then strongly broadening to form rounded lateraloapical lobes clearly separated distomedially, in lateral view median lobe weakly and almost evenly curved; ostium distally with pair of elongate hyaline lobes projecting distally; endophallus with long flagellum.
Female. Identity of paralectotype females remains unclear, so their characters and measurements are not included in redescription.
Distribution. Sri Lanka, near Colombo; Singapore, Thailand.
Remarks. The type series of S. pselaphoides includes 13 specimens, of which 8 are males representing three different species. However, externally all 13 specimens look almost the same and the three species can only be distinguished by the male genitalia. Possibly a larger sample would make it possible to find also some morphometric features differing between these species, but with seven males at hand this is not possible. I designate the male illustrated in Fig 21 as the lectotype of S. pselaphoides. This is the only male of this species, and all remaining males are excluded from the type series. All females are treated as impossible to identify. They become paralectotypes of S. pselaphoides (some may belong to this species and become identifiable if a larger sample is available in future), but the newly added identification labels read “? Scydmaenus pselaphoides ” to indicate identity problems. The two remaining species represented by males in the original Nietner’s type series of S. pselaphoides are discussed below.
The male specimen examined by Franz and listed in his 1982 paper under the name S. pselaphoides has a different aedeagus than any of the three species of the Nietner’s type series and has been misidentified.
This species has an unremarkable external morphology, like many other members of Scydmaenus s. str. from various continents. However, its aedeagus is unique among SE Asian species in the general shape, and especially in apical structures in ventral view. Scydmaenus (s. str.) singaporanus Franz, 1985a was described based on specimens collected in Singapore and Thailand, the aedeagus illustrated in the original description is indistinguishable from that shown in Fig. 37. I have in my collection a male specimen of S. singaporanus collected in Chiang Mai, Thailand. Its external morphology and aedeagus are indistinguishable from those of the lectotype of S. pselaphoides, so this is indeed one widely distributed species currently known to occur in Sri Lanka, Singapore and Thailand. Scydmaenus singaporanus Franz becomes a junior synonym of S. pselaphoides Nietner.
The true identity of the remaining two species (Figs 22, 23, 39–42) is unclear and it will require examination of several other species described from other regions of SE Asia, and solving a long-standing problem related to three names: S. mantcioranus (Schaufuss, 1884), S. minangkabauensis Blattný, 1926, and S. hoabinhensis Lhoste, 1938. Lhoste (1938): fig. 4 illustrated (only in lateral view) the aedeagus of a specimen that he identified as S. mantcioranus. His drawing looks almost identical to the aedeagus shown in Fig. 40 of the present paper (isolated from the male illustrated in Fig. 22 and referred to as “ Scydmaenus sp. 1 ”). Franz (1984) stated that he has examined the specimen studied by Lhoste, and that it was in fact S. minangkabauensis. The latter name was placed by Franz (1984) as a senior synonym of S. hoabinhensis. A new species bearing the latter name was described based on specimens from Vietnam, China, Sumatra, Java, and Sri Lanka, but it remains unknown whether Lhoste examined aedeagi of all specimens, or only one (which one?), and the remaining ones he identified by external characters. The latter would mean that identity of all undissected specimens is unknown, because many species of Scydmaenus (s. str.) do not differ in external characters. The aedeagus of S. hoabinhensis was illustrated in the same paper in which that of S. mantcioranus sensu Lhoste was shown (Lhoste, 1938: figs 8 and 4, respectively), they both are depicted in lateral views, and are strikingly different. The aedeagus of S. hoabinhensis illustrated by Lhoste is very similar to the aedeagus of the second of two species originally placed by Nietner in the type series of S. pselaphoides, as shown in Fig. 42 of the present paper (isolated from the male illustrated in Fig. 23 and referred to as “ Scydmaenus sp. 2 ”). Also, the aedeagus of “ S. hoabinhensis ” illustrated in Franz (1982): fig. 1 and in Franz (1989): fig. 7 is highly similar to that of Lhoste’s illustration for S. hoabinhensis (and to Fig. 42), and strongly differs from that illustrated for S. mantcioranus sensu Lhoste (= S. minangkabauensis sensu Franz), which is similar to Fig. 40 of the present paper. The synonymy of S. hoabinhensis and S. minangkabauensis in Franz (1984) is therefore proven erroneous by illustrations in Lhoste (1938) and in Franz (1982), which clearly show two separate species. In Franz (1982) the pronotum of S. hoabinhensis is described as “wenig länger als breit” (a little longer than wide), but Blattný (1926): fig. 2 illustrated his S. minangkabauensis (= S. hoabinhensis according to Franz) with a strikingly elongate pronotum, much longer than wide. Lack of illustrations of the aedeagi in dorsal or ventral views for each of these species makes it impossible to clarify this problem, because different species may have aedeagi highly similar in lateral view, but otherwise strongly different. The status of these three names and identity of species must be clarified by studying the type specimens. However, if S. hoabinhensis is indeed a junior synonym of S. minangkabauensis, records of this species from China, India, Indonesia, Nepal, Pakistan, Sri Lanka, Malaysia, Thailand, Taiwan, and Vietnam are not necessarily based on correctly identified specimens, so the distribution also requires verification. The same pertains to S. mantcioranus, which was recorded from Indonesia, Malaysia and Thailand, also not necessarily based on correctly identified specimens.
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 92-93, DOI: 10.11646/zootaxa.5633.1.4, http://zenodo.org/record/15372835