Zyras (Zyras) alternans
Creators: name: Assing, Volker
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Zyras
Zyras alternans

description: Zyras (Zyras) alternans (CAMERON, 1925)
(Figs 20, 58, 99, 166–169, Map 8)
Myrmedonia (Zyras) alternans CAMERON, 1925: 45 f.
Zyras (Zyras) optimus CAMERON, 1939a: 534; syn. n.
Type material examined: Z. optimus: Holotype ♀: “ Nilgiri Hills / Z. optimus Cam. Type / Zyras optimus Fvl n. sp., Désiré / M. Cameron. Bequest. 1955-147. / Holotype / Holotype Zyras optimus Cameron 1939, det. R.G. Booth 2016 / Zyras alternans (Cameron), det. V. Assing 2016” (BMNH).
Comment: Zyras alternans was described based on an unspecified number of syntypes from “ Sumatra, Lago Toba” (CAMERON 1925). The type material deposited in the natural history museum in Genova was revised and illustrated by PACE (2010b), who erroneously inferred from the type label attached to one of the specimens that it was the holotype.
The original description of Z. optimus is based on a unique holotype from “Nilgiri Hills” (CAMERON 1939a). This specimen is a female, but the male sexual characters, particularly the distinctive aedeagus, of the additional specimens examined from India and other regions (see below) are identical to those of the “ holotype ” of Z. alternans as figured by PACE (2010b). Thus, the holotype of Z. optimus is undoubtedly conspecific with the type material of Z. alternans.
Additional material examined: India: 1 ♂, Uttarakhand, left side of Kosi River, 5 km N Ramnagar, “N29*432 E79*140” [sic], 7–11.VI.2011, leg. Shavrin (cAss); 1 ♂, Tamil Nadu, Nilgiri Hills, Coonoor, 1700 m, 3.–5.X.1991, leg. Schuh (cAss); 1 ♂, Arunachal Pradesh, 8 km S Jamiri, Sessa env., 27°07–09'N, 92°34'E, 350 m, 26.V.–4.VI.2005, leg. Dembický (BMNH). Malaysia: 1 ♂, Pahang district, 30 km NE Raub, Laba Lembik, 3°56'N, 101°38'E, 300 m, 22.IV.–15.V.2002, leg. Jendek & Šauša (NMP); 1 ♀, Johor, 15 km N Lombong, Kota Tinggi, 27.–30.VII.1992, leg. Schuh (cAss). Indonesia: 1 ♂, West Java, Bogor, 6°33'S, 106°44'E, 180 m, rice field, flight interception trap, 6.VI.2011, leg. Puspitasari (cRou); 1 ♀, Jawa Barat, Bogor, Kebun Raya Bogor, 250 m, flight interception trap, 20.I.–7.II.2004, leg. Maruyama (cMar); 1 ♀, Sumatra-Aceh, 16 km S Kutacane, 350 m, 18.VIII.1992, leg. Barries & Cate (cAss); 1 ♂, 1 ♀, Borneo, E-Kalimantan, 55 km W Balikpapan, PT Fajar Surya Swadaya [area], 1°16'S, 116°21'E, 80 m, base camp surrounded by Acacia plantation, 23.XI.–1.XII.2011, leg. Hájek et al. (NMP, cAss).
Redescription: Body length 6.8–7.0 mm; length of forebody 3.0– 3.3 mm. Coloration (Figs 20, 58, 99): head black; pronotum pale-reddish; elytra black; abdomen reddish, with tergite VI reddish or extensively blackish (except for the anterior margin and the antero-lateral portions) and tergite VII always blackish (except for the anterior margin and the antero-lateral portions); legs pale-yellowish; antennae blackish; maxillary palpi blackish-brown with the terminal palpomere pale-yellowish.
Head (Fig. 58) transverse, 1.22–1.27 times as broad as long, broadly impunctate along middle; punctation in lateral dorsal portions moderately coarse and moderately dense. Eyes much longer than postocular region in dorsal view. Antenna (Fig. 20) 1.9–2.0 mm long; antennomeres IV approximately as long as broad, V–X of gradually increasing width and increasingly transverse, X approximately 1.5 times as broad as long, and XI approximately as long as, or slightly longer than the combined length of IX and X.
Pronotum (Fig. 58) 1.15–1.18 times as broad as long and 1.28–1.30 times as broad as head, broadest in anterior half, distinctly tapering posteriad; lateral margins straight in posterior half (dorsal view); punctation coarse, rather sparse, and irregularly distributed; laterally with extensive impunctate patches; midline broadly impunctate; lateral margins and antero-lateral portions with numerous long brown setae.
Elytra (Fig. 58) 0.80–0.87 times as long as pronotum; punctation coarse and defined, subject to sexual dimorphism; scutellum coarsely and granulosely sculptured anteriorly and smooth posteriorly. Hind wings fully developed. Metatarsomere I approximately as long as the combined length of II–IV.
Abdomen (Fig. 99) slightly narrower than elytra, with moderately deep anterior impressions on tergites III–V; tergite II with coarse non-setiferous punctation; tergites III–IV each with a transverse row or band of coarse non-setiferous punctures in anterior impressions, with a lateral setiferous puncture on either side, and with 4–6 setiferous punctures at posterior margins; tergite V with a transverse row or band of coarse nonsetiferous punctures in anterior impression, with or without a median pair of setiferous punctures, with a lateral setiferous puncture on either side, and with 6–8 setiferous punctures at posterior margin; tergite VI with a more or less extensive transverse band of coarse non-setiferous punctures anteriorly, with one or few lateral punctures on either side, and with 6–8 setiferous punctures at posterior margin; tergite VII with a more or less extensive transverse band of numerous non-setiferous punctures anteriorly, with one or two transverse series of setiferous punctures posteriorly; tergite VIII (Fig. 168) with approximately 20 black setae posteriorly, posterior margin more or less disinctly concave in the middle.
♂: punctation of elytra very dense and asperate near anterior margin and near scutellum; sternite VIII (Fig. 169) with convex posterior margin; median lobe of aedeagus 0.72–0.78 mm long and shaped as in Figs 166–167; ventral process very short and apically hooked in lateral view; paramere 0.83–0.90 mm long, with very short apical lobe.
♀: punctation of elytra defined and clearly separated, not asperate, only slightly denser anteriorly than posteriorly.
Intraspecific variation: The coloration of tergite VI, the punctation of the elytra, and the non-setiferous punctation of the abdomen appear to be highly variable in this species. Tergite VI is extensively infuscate in the middle and posteriorly in the holotype and the specimens seen from Arunachal, Malaysia and Indonesia, whereas it is uniformly reddish in the remaining non-type specimens from India.
Comparative notes: Zyras alternans is distinguished from other sympatric species with a similar colour pattern by its relatively large size, robust body, black antennae, the coarse non-setiferous punctation of the abdomen, and above all by the distinctive shape of the median lobe of the aedeagus.
Distribution and natural history: Records from North and South India, as well as from Malaysia, West Java, Sumatra, and Borneo (Map 8) indicate a vast distribution of Z. alternans. The altitudes range from 80 to 1700 m. At least most of the specimens were collected on the wing.
description: Published as part of Assing, Volker, 2017, On Zyras sensu strictu in the East Palaearctic and Oriental regions, with a focus on the faunas of the Himalaya, India, Sri Lanka, Thailand, and Sulawesi (Coleoptera: Staphylinidae: Aleocharinae: Lomechusini), pp. 117-192 in Beiträge Zur Entomologie = Contributions to Entomology 67 (1) on pages 141-142, DOI: 10.21248/contrib.entomol.67.1.117-192, http://zenodo.org/record/5742363