Arthromelodes weii, Zhang & Yin, 2025

Zhang, Yong-Qin & Yin, Zi-Wei, 2025, The ant-like litter beetle fauna from the Wumenshan National Nature Reserve, China, with description of eight new species (Staphylinidae: Pselaphinae), European Journal of Taxonomy 1007, pp. 133-162 : 138-141

Arthromelodes weii sp. nov.

urn:lsid:zoobank.org:act:E0D65BA1-22CD-4063-8879-6E243C5409CA

Fig. 2

Chinese common name

魏oi丽º甲.

Diagnosis

Male

Body length approximately 2.0– 2.1 mm. Head and pronotum coarsely punctate. Head subrectangular, truncate at base; vertexal foveae small and asetose, lacking sulcus connecting them; gular with small, lamellar-like protuberance at middle; antenna relatively long, antennomeres each more or less elongate, lacking modifications. Prosternite densely setose at middle. Elytra constricted and truncate at bases; shallow discal striae extending posteriorly to approximately 3 / 5 of elytral length. Mesotrochanter with short tubercle on ventral margin. Abdomen with tergite 1 (IV) slightly longer than 2–4 (V–VII) combined, simple. Aedeagus strongly asymmetric, median lobe with large basal capsule and subtriangular foramen, ventral stalk of median lobe broad in ventral view, narrowing apically in lateral view; dorsal lobe as long as ventral stalk, expanded at middle in lateral view, with narrowed apex.

Female

Body length approximately 1.8–2.0 mm; gular, prosternite and mesotrochanter simple; genitalia as in Fig. 2J .

Etymology

This species is named in honour of Guo-Hao Wei, who collected the type series. The specific epithet is a patronym formed as a noun in the genitive singular case.

Type material

Holotype

CHINA • ♂; Yunnan, Zhaotong City, Wumengshan Conservation Area, Laziping ; 28°9′0″ N, 103°33′49″ E; 1952 m a.s.l.; 15 Jul. 2022; Wei leg.; Ǖ南昭ª市乌®山小ẽữ, 魏ǡ豪*; SNUC.

Paratypes

CHINA • 3 ♂♂, 7 ♀♀; same data as for holotype; SNUC .

Description

Male

BODY ( Fig. 2A ). Length 2.04–2.08 mm; colour reddish-brown, tarsi and mouthparts lighter in colour. Dorsal surface of body covered with relatively short pubescence.

HEAD ( Fig. 2B ). Subrectangular, truncate at base, slightly wider than long, length 0.42–0.45 mm, width 0.48–0.49 mm; vertex coarsely punctate, with small, asetose and moderately separated vertexal foveae (dorsal tentorial pits), lacking mediobasal carina; antennal tubercles moderately raised; frons broadly and shallowly impressed medially, anteriorly fused with clypeus; clypeus short, roughened, its anterior margin carinate and moderately raised; ocular-mandibular carinae complete. Venter with tiny gular foveae (posterior tentorial pits) in shared small opening, with small lamellar-like protuberance ( Fig. 2C– D ) at middle, with faint median carina present for short distance posterior to mouthparts. Compound eyes prominent, each composed of approximately 25 ommatidia. Antenna 1.0– 1.14 mm long, lacking modifications; antennomere 1 thick and short, anterolateral margin with dense setae, antennomeres 2–7 each slightly elongate, 8 smallest, moniliform, 9 and 10 approximately subequal in width, 11 slightly longer than 9 and 10 combined (24:20), subconical.

PRONOTUM ( Fig. 2B ). Slightly wider than long, length 0.45–0.48 mm, width 0.46–0.49 mm, widest at middle; lateral margins rounded; disc moderately convex, coarsely punctate, with median longitudinal sulcus slightly longer than semicircular lateral sulci in dorsal view; with median antebasal impression, with complete, deep transverse antebasal sulcus connecting lateral antebasal foveae. Prosternum ( Fig. 2E ) with basisternal (precoxal) portion longer than procoxal rests, at middle with deep, setose transverse sulcus, anterior margin of sulcus protruding and densely setose; hypomeral grooves obliquely extending from base anteriorly to half-length of hypomera, with lateral antebasal hypomeral impression, hypomeral ridges short, close to margins of coxal cavities.

ELYTRA. Much wider than long, length 0.61–0.66 mm, width 0.73–0.74 mm; distinctly constricted and truncate at bases; each elytron with one small basal fovea; shallow discal striae extending from bases posteriorly to 3 /5 of elytral length; humeri lacking prominence or denticle; subhumeral foveae absent, thin marginal striae extending posteriorly from foveae to posterior margins of elytra. Metathoracic wings absent.

MESOVENTRITE. Short, laterally fully demarcated from metaventrite by oblique ridges; median mesoventral foveae moderately separated, originating from shared setose, transverse opening, lateral mesoventral foveae large and setose, forked internally; prepectus massive, collar-shaped; mesoventral intercoxal process short, apically acute; marginal striae complete. Metaventrite weakly impressed at middle, with large, setose lateral mesocoxal foveae and pair of smaller, setose lateral metaventral foveae, metaventral intercoxal process with small and narrow split at middle.

LEGS. Elongate, fore and hind legs simple; mesotrochanter ( Fig. 2F ) with short, blunt tubercle on ventral margin.

ABDOMEN. Distinctly narrower than elytra, widest at basolateral margins of tergite 1 (IV), length 0.63– 0.65 mm, width 0.66–0.67 mm; lacking modifications. Tergite 1 (IV) slightly longer than 2–4 (V–VII) combined, thin basal sulcus interrupted by one pair of mediobasal and two pairs of basolateral foveae, discal carinae short and distinct; tergites 2 and 3 (V and VI) each short, lacking fovea, 4 (VII) slightly shorter than 2 and 3 combined along middle, with one pair of small basolateral foveae, tergite 5 (VIII) semicircular, transverse. Sternite 2 (IV) with one pair of mediobasal foveae and two pairs of large basolateral sockets, lacking lateral carinae; midlength of sternite 2 slightly shorter than 3–5 (V–VII) combined, 3–5 each short, successively shorter, lacking fovea, 6 (VIII) transverse, posterior margin roundly emarginate at middle, sternite 7 (IX) ( Fig. 2G ) with weakly sclerotized, rounded apex and few setae along apical margin.

AEDEAGUS ( Fig. 2H–I ). 0.36 mm long, strongly asymmetric; median lobe with large basal capsule and subtriangular foramen, basoventral projection short, ventral stalk of median lobe in lateral view narrowing apically, dorsoventrally broad through length; dorsal lobe in lateral view elongate and expanded at middle, with narrowed apex; parameres reduced.

Female Similar to male in external morphology; antenna slightly shorter, mesotrochanter lacking tubercles; each compound eye composed of approximately 20 ommatidia; head venter and prosternum lacking modifications. Measurements (as for male): body length 1.86–1.94 mm; length/width of head 0.39–

0.40/ 0.44–0.46 mm, pronotum 0.42–0.43/ 0.42–0.43 mm, elytra 0.57–0.59/ 0.59–0.66 mm; abdomen 0.61–0.65/ 0.61 mm; length of antenna 0.92–0.97 mm; genitalia ( Fig. 2J ) moderately sclerotized, broad, maximum width 0.26 mm.

Remarks

This species of Arthromelodes is easily recognizable based on its coarsely punctate head and pronotum, as well as the simple male abdomen. Notably, the modifications present on the head venter and prosternite are uniquely observed within the genus, making this species particularly distinctive.

Distribution

Southwest China: Yunnan.

Figures

Fig. 2. Arthromelodes weii sp. nov. A–I. Holotype, ♂ (SNUC). J. Paratype, ♀ (SNUC). A. Dorsal habitus. B. Head and pronotum. C. Head venter. D. Head, in lateral view. E. Prosternum. F. Mesotrochanter. G. Sternite 7 (IX). H. Aedeagus, lateral view. I. Aedeagus, ventral view. J. Genitalia, ventral view. Scale bars: A = 0.5 mm; B = 0.3 mm; C–F = 0.2 mm; G = 0.05 mm; H–J = 0.1 mm.