Anaclasiger zhudaiae Yin & Huang, 2012

Yin, Zi-Wei, 2023, Range extension and male description of a rare clavigerite beetle in China (Coleoptera: Staphylinidae: Pselaphinae), Zootaxa 5357 (4), pp. 595-600 : 596-600

Anaclasiger zhudaiae Yin & Huang, 2012

( Figs 1–3 )

Anaclasiger zhudaiae Yin & Huang in Yin et al. 2012: 600. Type locality: “ China: Guangdong Prov., Shenzhen, Yantian Dist., Yantian Station [22°36′33″N, 114°15′30″E]”.

Chinese common name: ̐ṣ̊ssfȉăş

Material examined. 4 ♁♁, 6 ♀♀, ‘ China: Hunan, Changsha City, Xiangbiwo Forest Park, 28°9′43.95″N, 112°50′52.77″E, 120 m, 12.viii.2023, ant nest, under stone, Ming Li leg., DZẐẗ ̋ĸāġ¨̈ȓǡṛēffl ’ ( SNUC) .

Updated diagnosis. Male. Habitus elongate, with relatively long antennae and legs. Body length approximately 2.0 mm. Head much longer than wide, 1.43× as long as wide, frontal rostrum broad and projected; antenna elongate, with short antennomeres 1 and 2 and long 3 and 4; antennomere 4 distinctly curved at middle, 2.28× as long as 3. Pronotum elongate, lateral margins with deep incisions posterior to middle. Discal striae of elytra extending posteriorly for 2/3 elytra length (along shoulder), posterior margin of elytra with scattered long setae, lacking trichomes. Metaventrite projecting posteromedially and with long bunch of setae. Mesotibia broadly and roundly expanded before apex.Abdomen suboval; composite tergite deeply concave at base, with small patches of trichomes and long sinuate lateral carinae. Aedeagus dorso-ventrally slightly asymmetric, divided into basal and apical part, apical part gradually narrowing toward apex; endophallus armature composed of two twisted, elongate sclerites. Female. Body length approximately 2.1–2.2 mm; mesotibia before apex lacking expansion; metaventrite lacking posteromedial projection and bunched setae; genital structures see Yin et al. 2012: figs 6–8.

Redescription (based on population of Hunan). Male. Body ( Fig. 1A ) length 1.96 mm; color reddish-brown, tarsi and mouthparts lighter in color. Dorsal surface of body covered with sparse, short pubescence.

Head ( Fig. 1B ) subcylindrical, much longer than wide, length 0.38 mm, width across eyes 0.26–0.27 mm; vertex at middle weakly convex, with distinct, asetose vertexal foveae (dorsal tentorial pits) situated below level of posterior margin of eyes; frons broadening and rising anteriorly, forming distinct rostrum; clypeus sharply descending, densely setose. Venter with rough surface, gular region broadly and deeply concave, tiny gular foveae (posterior tentorial pits) widely separated, lacking median carina. Compound eyes prominent, each composed of approximately 25 ommatidia. Cervical part sub-globose, dorsal surface with distinct reticulate microsculpture. Antenna ( Fig. 1C ) 0.89–0.92 mm long, lacking modification; antennomere 1 thick and short, only partially visible dorsally, 2 as long as 1, subcylindrical, 3 approximately 2.5× as long as 2, slightly curved at middle, 4 largest, approximately 2.3× as long as 3, greatly curved at middle, rounded at apex, lacking truncate apical cavity.

Pronotum ( Fig. 1B ) distinctly longer than wide, length 0.36–0.37 mm, width 0.32 mm, widest at approximately 1/4; lateral margins rounded at widest point, deeply incised at basal 2/5; disc at middle broadly concave in basal half, lacking fovea, posterior margin with transverse linear microsculpture. Prosternum with anterior part longer than coxal part, lacking procoxal foveae; hypomera largely fused with sternum, with faint hypomeral carinae.

Elytra subtrapezoidal, much wider than long, length 0.52–0.54 mm, width 0.70–0.72 mm, lacking foveae; anterior margin carinate, extending laterally to form angulate anterolateral corners; discal striae long, oblique, extending from humeral corners to apical 2/3 of elytral length; each elytron with roundly convex posterior margin, margin with few scattered long setae. Metathoracic wings fully developed.

Mesoventrite short, fused with metaventrite; small, asetose median mesoventral foveae separated by median keel, which is angularly projecting at middle. Metaventrite greatly convex at middle and descending laterally, lacking foveae, median part with distinct linear and small lateral area with reticulate microsculpture, posterior margin ( Fig. 1D ) at middle angularly elevated and with long bunch of setae on projection.

Legs elongate; mesotibia ( Fig. 1E ) roundly and broadly expanded before apex.

Abdomen as wide as elytra, oval, widest at basolateral margins of composite tergite, length 0.63–0.68 mm, width 0.70–0.72 mm. Tergite 1 (composite tergite formed by tergites IV–VI) deeply concave at base, with pair of basolateral foveae in large sockets, small patches of trichomes lateral to sockets, with long, sinuate lateral carinae extending from posterior margins of sockets to posterior margin of tergite, 2 (VII) short, transverse, with pair of lateral nodules, 3 (VIII) (Fig, 1F) transverse, with pair of small basolateral foveae, posterior margin broadly emarginate at middle. Sternites with distinct reticulate microsculpture, 2 (IV) broadly and deeply concave in basal half, with two large basal lateral foveae, 3 (V) at middle as long as 4 (VI) and 5 (VII) combined, 6 (VIII) ( Fig. 1G ) transverse, posterior margin shallowly emarginate at middle, 7 (IX) ( Fig. 1H ) composed of paired membranous plates.

Aedeagus ( Fig. 1I, J ) 0.45 mm long, dorsoventrally slightly asymmetric; median lobe divided into basal capsule and apical lobe, lacking parameres; basal capsule elongate, thick and rounded at base, with distinct ventral projection and small foramen, dorsally with large, oval diaphragm, apical lobe in lateral view sinuate, narrowing apically and with pointed apex; endophallus armature composed of two elongate and twisted sclerites in apical half.

Female. Similar to male in external morphology; each eye composed of 23–26 ommatidia; mesotibia lacking expansion near apex; metaventrite lacking posteromedial projection and bunched setae; metathoracic wings fully developed; abdomen relatively larger. Measurements (as for male): body length 2.09–2.16 mm; length/width of head 0.38–0.41/ 0.27–0.29 mm, pronotum 0.37–0.39/ 0.33–0.35 mm, elytra 0.53–0.56/ 0.74–0.79 mm; abdomen 0.76–0.78/ 0.77–0.81 mm; length of antenna 0.91–0.95 mm.

Comparative notes. Although only a single female was known before this study, the species is well separated from its sole congener, A. sinuaticollis , by its much more elongate habitus, antennae, and legs. After the discovery of the male, additional characters such as the broadened mesotibiae and the modified metaventrite further separate them ( A. sinuaticollis has simple male mesotibiae and metaventrite). The general shape and structure of the endophallus armature of the aedeagus are similar to those of A. sinuaticollis , suggesting a close relationship between these species.

Biology. All specimens were collected from colonies of Nylanderia flaviabdominis (Wang) ants nesting under stones or in decaying logs. The host ( Fig. 3B–D ) is the same as that for the type locality population. The beetles and a small group of ant workers were kept alive in the laboratory for observation for a few days ( Fig. 2 ); and it appeared that the clavigerites were ignored by the hosts most of the time.

Distribution. Central China: Hunan; South China: Guangdong ( Fig. 3A ). New provincial record for Hunan.

Figures

FIGURE 1. Habitus and morphological details of Anaclasiger zhudaiae, male. A. Dorsal habitus. B. Head and pronotum. C. Antenna, ventral. D. Metaventrite, showing posteromedial projection and setae. E. Mesotibia. F. Tergite 5 (VIII). G. Sternite 6 (VIII). H. Sternite 7 (IX). I, J. Aedeagus, ventral (I), and lateral (J). Scale bars: 0.5 mm in A; 0.3 mm in B–E; 0.1 mm in F–H; 0.2 mm in I, J.

FIGURE 2. A, B. Ex-situ photographs of Anaclasiger zhudaiae beetles with their host, Nylanderia flaviabdominis ants.

FIGURE 3. A. Distribution of Anaclasiger; circle—A. sinuaticollis, rectangle—A. zhudaiae, dotted outline indicates new record. B–D. Nylanderia flaviabdominis, host of A. zhudaiae; habitus, lateral (B), dorsal (C), and full face (D). Scale bars: 0.5 mm in B, C; 0.3 mm in D.