Trissemus (Trissemus) melinus
Creators: name: Yin, Zi-Wei
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Trissemus
Trissemus melinus

description: Trissemus (Trissemus) melinus (Solsky, 1870)
(Fig. 2)
Chinese common name: ffioiūḎƤ
Bryaxis melina Solsky, 1870: 462 (replacement name for B. rubra Motschulsky, 1851: 492, nec. B. rubra Aubé, 1844: 115).
Bryaxis tychoides Reitter, 1877: 291.
Bryaxis (Reichenbachia) melina; Reitter 1882: 475.
Reichenbachia melina; Raffray 1904: 360, 1908: 240, 1911: 102.
Trissemus lindbergi Jeannel, 1959: 19.
Trissemus melinus; Besuchet 1961a: 2, 1961b: 42, I. Löbl & Besuchet 2004: 302, Schülke & Smetana 2015: 406, Hlaváč & Nakládal 2014: 536.
Material examined. 3 ♁♁, labeled ‘ Xinjiang, Fukang, Baisihumu Vill.; N44.2711, E88.0894, 500 m, dry land; 2018. VIII.06, light trap; Shi H & Yang G. leg., ỀṞḌDzfflpḄOiϮϋ ’ (SNUC).
Diagnosis. Male. Body length 1.6–1.8 mm; antennomere 5 enlarged, 6 to 8 each broadened at their mesal margin; mesotrochanter with distinct ventral projection, mesotibia with long preapical spine; median lobe of aedeagus with one small, acute protrusion at middle of apex, parameres enlarged apically, endophallus composed of numerous spine-like structures.
Redescription. Male. Body (Fig. 1A) length 1.64–1.78 mm; color reddish-brown, tarsi and mouthparts paler. Dorsal vestiture finely punctate and covered with short setae.
Head (Fig. 2A) truncate at base, approximate as long as wide, length 0.38–0.40 mm, width 0.38 mm; vertex weakly convex, with large, setose foveae (dorsal tentorial pits); antennal tubercles barely raised; frons with distinct setose fovea, lacking rostrum; clypeus fused with frons, evenly descending, its surface finely punctate, anterior margin rounded and weakly carinate; ocular-mandibular carina absent. Venter with two small, well-separated gular foveae (posterior tentorial pits), median longitudinal ridge moderately convex. Maxillary palpus distinct, palpomere 1 minute, 2 pedunculate basally and broadened apically, 3 roundly trapezoidal, 4 truncate at base, broadest at approximately basal 1/3 and gradually narrowing apically, with long palpal cone. Compound eye greatly prominent, roundly reniform in lateral view, each composed of approximately 36 ommatidia. Antenna moderately elongate, length 0.87–0.89 mm, with modified antennomeres 5–8 (Fig. 1C) and clubbed 9–11; antennomere 1 large, subcylindrical, 2 slightly narrower and much shorter than 1, 3 as long as 2 but distinctly narrower, 4 much shorter than 3, 5 enlarged, slightly shorter than 6 and 7 combined, 6–8 each broadened at mesal margin and successively shorter, 9 as wide as 8 but much longer, subquadrate, 10 slightly broader and longer than 9, 11 largest, longer than 9 and 10 combined, roundly truncate at base, broadest near middle, narrowing from widest point toward apex.
Pronotum (Fig. 2B) slightly wider than long, length 0.35–0.36 mm, width 0.41 mm, widest at middle; sides rounded, narrowing from widest point anteriorly and posteriorly, both anterior and posterior margin slightly arched; disc moderately convex, lacking carina or sulcus; with small, punctiform median and large, setose lateral antebasal foveae. Prosternum with anterior part much shorter than coxal part at middle, with large, asetose lateral procoxal foveae widely separated; hypomeron with short ridge in basal half that separates it from pronotum; margin of coxal cavity non-carinate.
Elytra much wider than long, length 0.56–0.61 mm, width 0.76–0.78 mm, truncate at bases; each elytron (Fig. 2D) with three asetose basal and one tiny subbasal fovea; sutural stria complete, discal one extending from outer fovea to apical 1/10 of elytral length; humeral region lacking subhumeral fovea or marginal stria; posterolateral margin slightly notched laterally. Metathoracic wings fully developed.
Mesoventrite laterally fused with metaventrite, with single median mesoventral fovea greatly extended internally, large lateral mesoventral foveae unforked, extended internally and meet each other at middle; inter-coxal process moderately long, with round apex. Metaventrite moderately prominent admesally; with large lateral metaventral and moderately large lateral mesocoxal foveae; posterior margin broadly and roundly emarginate at middle.
Legs elongate; mesotrochanter with curved ventral projection accompanied with one macroseta, metatibia with large, long preapical spine.
Abdomen widest at base of tergite 1 (IV), length 0.45–0.59 mm, width 0.69–0.72 mm, segments 1–4 with well-developed paratergites. Tergite 1 (IV) dorsally much longer than 2 (V) and 3 (VII) combined, basal impression weak, with two pairs of basolateral foveae; discal carinae long, moderately divergent posteriorly; 2 to 4 (VIII) successively shorter, each with one pair of basolateral foveae; 5 (VIII) transverse, posterior part greatly narrowing toward middle. Sternite 2 (IV) longest, with one pair of basolateral foveae, 3 to 5 (V–VII) each short at middle, compact, lacking sulcus or fovea at base, 6 (VIII) transverse, posterior margin slightly roundly emarginate at middle, 7 (IX) (Fig. 2F) with pair of membranous lamellae.
Aedeagus (Fig. 2E, F) 0.41 mm long, dorso-ventrally symmetric; median lobe with large, round basal capsule and small acute spine at middle of apex; parameres broad, enlarged at apices; endophallus composed of numerous small spines.
Female. Not examined.
Biology. All individuals were collected together with Brachygluta iranica by a light trap set in a dryland with few desert plants.
Distribution. Russia (southern European part), Armenia, Azerbaijan, Kazakhstan, Tadzhikistan, Turkmenistan, Uzbekistan, Afghanistan (Newton 2022), China (Xinjiang). New country record for China.
Remarks. This species is newly recorded and represents the second Trissemus from China (the first being T. implicitus (Raffray, 1912) on Taiwan island). In China the genus is much more diverse than is presently documented, and more than 50 new species have been examined by the author (pers. obs.).
A few specialists (e.g., Chandler 2001) have questioned the validity of Trissemus. Except for having three basal foveae on each elytron, the genus appears to possess no distinct characteristics that may serve to separate it from Reichenbachia Leach. The male of Reichenbachia spatulifer Casey, 1897 from Canada and USA has the antennae and mesotibiae modified in a similar form, and also has three basal elytral foveae. It may be separated from T. melinus by the larger body size (2.1 mm vs. 1.6–1.8 mm), deeper discal striae of the elytra, and angularly inflated metatibiae of the male (metatibiae simple in T. melinus).
description: Published as part of Yin, Zi-Wei, 2022, First pselaphine beetles from Xinjiang Uygur Autonomous Region, China (Coleoptera: Staphylinidae: Pselaphinae), pp. 495-500 in Zootaxa 5222 (5) on pages 497-499, DOI: 10.11646/zootaxa.5222.5.8, http://zenodo.org/record/7471965