Archiclaviger gaofani, Yin & Hlaváč & Cuccodoro, 2020

Yin, Zi-Wei, Hlaváč, Peter & Cuccodoro, Giulio, 2020, The first record of Archiclaviger in continental Asia, with description of a new species from China (Coleoptera: Staphylinidae: Pselaphinae), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 60 (2), pp. 537-544 : 539-543

Archiclaviger gaofani sp. nov.

( Figs 1–3 ; 5 )

Chinese common name: Ŕ氏Ŝ寡Ṫȃm

Type material. Hඈඅඈඍඒඉൾ: CHINA: J, ‘ China: Jiangsu,Changzhou, Jintan Dist., nr. cross of S240/S340 HWY, 31º45′45.64″N, 119º36′38.40″N E, 2 m, 18.iii.2020, F. Gao leg., 常州ȑ坛 S240/S340 交叉ñ口 (four workers of the host ant are pinned under the specimen)’ (SNUC). Pൺඋൺ- ඍඒඉൾ: CHINA: 1 ♀, same collection data as holotype (one worker and one male of the host ant are pinned under the specimen) (SNUC).

Comparative diagnosis. The female of the new species can be readily separated from A. overbecki from Java (known from a single female) by the relatively much shorter antennomeres 4–5, the presence of a pair of admesal carinae on the gular plate of the head (lacking in A. overbecki ), the posterior margin of the elytra and the base of the abdomen with only few setae (with row of dense, long golden setae in A. overbecki ), the more convex disc of the abdomen with fewer long, thick setae, and the relatively longer sternite 2 (IV) in relation to sternite 3 (V). Description. [ Figs 2 and 3B are based on a female specimen, but the morphology is the same in both sexes.] Male ( Figs 1A, B ). Body length (from anterior margin of clypeus to apex of abdomen) 2.27 mm; reddish-brown. Head ( Figs 2B–D, C ) longer than wide, length from anterior margin of clypeus to head base along midline (excluding neck region) 0.40 mm, width across eyes 0.33 mm; anteri- or margin of clypeus protuberant and slightly arcuate, gular plate ( Fig. 2C ) with pair of admesal carinae extending from posterior tentorial pits (gular foveae) to mouthpart; each eye composed of approximately 30 facets. Antenna ( Fig. 2A ) clubbed, length of exposed part 0.71 mm; scape and pedicel short, antennomere 3 elongate, slightly and evenly broadening distally, antennomere 4 shorter and slightly broader than 3, elongate, antennomere 5 shorter and at apex slightly broader than 4, broadening from base toward apex, antennomere 6 much broader than 5, shorter than 4 and 5 combined, with truncate and densely setose apex. Pronotum ( Fig. 2B ) subglobose, slightly transverse, length along midline 0.38 mm, maximum width 0.41 mm, with broad median longitudinal impression. Prosternum ( Fig. 2C ) with weak median carina, anterior margin of procoxal cavities slightly carinate. Elytra ( Figs 1A, B ; 2D ) roundly trapezoidal, much wider than long, length along suture 0.61 mm, maximum width 0.92 mm; lacking trichomes at posterior margins. Mesoventrite ( Fig. 2E ) with golden setae along midline, with short carinae at base; metaventrite ( Fig. 2E ) medially strongly convex, with scattered long, golden setae, with microsculpture in area posterior to coxal cavities. Legs short; mesofemur ( Fig. 3A ) with large, curved ventral projection at base, apex of projection bifid; mesotibia ( Fig. 3A ) with large triangular preapical spine in apical fourth.Abdomen ( Fig. 1A ) rounded, approximately as long as wide, and slightly narrower than elytra, length along midline 0.80 mm, maximum width 0.86 mm, disc ( Fig. 1B ) strongly convex dorsally; composite tergite ( Fig. 2D ) broadly and deeply concave at base, lacking basolateral trichomes; both paratergites of first pair bearing group of linear trichome. Sternite 1 (III) and basal margin of sternite 2 (IV) ( Fig. 3B ) with rhombic microsculpture, sternite 2 (IV) along middle 1.35 times as long as sternite 3 (V), sternites 3 (V) and 4 (VI) along middle each approximately twice as long as their next segment. Aedeagus ( Figs 3C–E ) strongly sclerotized, symmetrical, length 0.59 mm; median lobe undivided, apex pointed; endophallus composed of two elongate sclerites.

Female ( Fig. 1C ). Similar to male in external morphology; body size slightly larger; each eye composed of approximately 30 facets. Measurements (as for male): body length 2.32 mm, length/width of head 0.41/ 0.33 mm, pronotum 0.38/ 0.41 mm, elytra 0.60/ 0.89 mm, abdomen 0.85/ 0.87 mm, length of antenna 0.69 mm.

Etymology. The new species is named after Fan Gao (Nanjing University, Jiangsu, China), who collected this interesting species, and kindly donated the material to the SNUC.

Biology and host ant. Both individuals were collected in March with a Nylanderia ant nesting under concrete blocks in a small green space in a highly industrial area of Jintan City ( Figs 5A, B, D ). An attempt to find additional specimens in the same locality by the first author on August 24, 2020 failed, possibly because it was already too late in season, but the presence of the same ant species was confirmed.

Distribution. Eastern China: Jiangsu ( Fig. 5C ).

Figures

Fig. 1. Archiclaviger gaofani sp. nov. A–C – habitus (A – dorsal, male; B – lateral, male; C – dorsal, female); D – frontoventral view of antennal bases, showing antennal fossae and scapes.Abbreviations: a1–3 = antennomere 1–3. Scale bars: 0.5 mm in A–C; 0.2 mm in D.

Fig. 2. Morphology of Archiclaviger gaofani sp. nov. A – antenna; B – head and pronotum; C – head venter and prosternum; D – elytral apex and base of abdomen; E – meso- and metaventrite. Abbreviations: a2–6 = antennomere 2–6. Scale bars: 0.2 mm in A, D; 0.3 mm in B, C, E.

Fig. 3. Morphology of Archiclaviger gaofani sp. nov. A – middle leg; B – abdominal sternites; C–E – aedeagus, dorsal (C), lateral (D), and ventral (E). Scale bars: 0.3 mm in A, B; 0.2 mm in C, D, E.

Fig. 5. Collection site, distribution and host ant of Archiclaviger. A – environment of the collection site of A. gaofani sp. nov.; B – the collection site of A. gaofani sp. nov. is located in a highly industrial area of Jintan District, Changzhou; C – distribution of Archiclaviger species in Asia; D – a living adult of A. gaofani sp. nov. was discovered in a nest of Nylanderia ants after a concrete block had been turned over (photo by F. Gao).