Triomicrus wumengmontis, 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 : 156-160

Triomicrus wumengmontis sp. nov.

Chinese common name: 乌®山鞭须ü甲 urn:lsid:zoobank.org:act:75EE1DDE-941D-489B-8EDD-555C30A94C7F Fig. 8

Diagnosis

Male

Body length approximately 1.8–1.9 mm. Head and pronotum coarsely punctate. Eyes much shorter than tempora. Antennomere 11 simple, lacking modifications. Pronotum distinctly transverse. Elytra with short humeral striae extending for short distance. Protibia protuberant at apex; mesotibia with spine at apex. Posterior margin of sternite VII with hook-like expansion on left side. Aedeagus with left paramere (orientation according to figure) larger than right one, endophallus armature composed of three to four short, blunt sclerotized spines at middle of posterior half of capsule.

Female

Unknown.

Etymology

The specific epithet is derived from the Wumengshan Natural Reserve, the type locality for this species. The name is a noun in the genitive case.

Type material

Holotype

CHINA • ♂; Yunnan, Zhaotong City, Wumengshan Natural Reserve, Haiziping , Dalingou ; 27.8799 ° N, 104.720011° E; 1180 m a.s.l.; 23 Jul. 2022; Wei leg.; Ǖ南昭ª乌®山AEŦū大ḢÁ魏ǡ豪*; SNUC.

Paratypes

CHINA • 1 ♂; same data as for holotype; SNUC .

Description

Male BODY ( Fig. 8A ). Length 1.78–1.86 mm; colour reddish-brown, tarsi and mouthparts paler. Head and pronotum coarsely punctate, elytra and abdomen finely punctate; vestiture covered with moderately long setae.

HEAD ( Fig. 8B ). Roundly rectangle, subtruncate at base, approximate as long as wide, length 0.47– 0.49 mm, width 0.43–0.44 mm; vertex weakly convex, with broadly separated, setose foveae (dorsal tentorial pits); antennal tubercles barely raised; frons with distinct setose fovea, forming short rostrum; clypeus fused with frons at middle, evenly descending, with coarse surface, anterior margin arcuate and markedly carinate; ocular-mandibular carinae complete. Venter with two small, well-separated gular foveae (posterior tentorial pits), median longitudinal ridge broad and greatly convex. Maxillary palpus elongate; palpomere 1 minute; 2 extremely slender and long, pedunculate basally and broadened at basal ⅓ and at apex; 3 roundly trapezoidal, with short stem at base; 4 fusiform, with distinct stem at base, broadest at basal 2 /5, with long palpal cone. Compound eye relatively small, reniform in lateral view, each composed of approximately 25 ommatidia. Antenna moderately elongate, length 0.95–0.98 mm, lacking modifications, club formed by apical two antennomeres; antennomere 1 large, subcylindrical, 2 slightly narrower and shorter than 1, 3–8 each submoniliform, gradually shorter, 9 distinctly larger than 8, transverse, 10 much larger than 9, 11 ( Fig. 8C ) largest, much longer than 8 and 9 combined (27:16), subconical, obliquely narrowed at apex.

PRONOTUM ( Fig. 8B ). Much wider than long, length 0.43–0.45 mm, width 0.54 mm, widest at middle; sides rounded, narrowing from widest point anteriorly and posteriorly, both anterior and posterior margin almost straight; disc weakly convex, lacking carina or sulcus; with moderately distinct, setose median and lateral antebasal foveae; basal portion roughened. Prosternum with basisternal (precoxal) portion approximately as long as procoxal rests; with large, widely separated and setose lateral procoxal foveae; hypomera fully demarcated from pronotum by complete hypomeral grooves, hypomeral carinae close to coxal cavities.

ELYTRA. Roundly trapezoidal, wider than long, length 0.71–0.73 mm, width 0.82–0.84 mm, truncate at bases; each elytron with two asetose basal foveae; sutural striae complete, discal striae extending from outer fovea to approximately apical ¾ of elytral length; humeri roundly prominent, with small subhumeral foveae and thin marginal striae extending for less than half of elytral length; posterior margin slightly notched laterally. Metathoracic wings present but reduced for some extent.

MESOVENTRITE. Laterally fused with metaventrite, with median mesoventral foveae in single setose oval impression, large lateral mesoventral foveae unforked, extended internally and meeting each other at middle; intercoxal process short and narrow, with round apex. Metaventrite moderately prominent admesally; with large lateral metaventral and lateral mesocoxal foveae; posterior margin broadly and roundly emarginate at middle.

LEGS. Elongate; protibia ( Fig. 8D ) with small tubercle at apex; mesotibia ( Fig. 8E ) with acute apical spine.

ABDOMEN. Narrower than elytra, widest at base of tergite 1 (IV), length 0.43–0.45 mm, width 0.71– 0.73 mm, tergites 1–4 with well-developed accompanying paratergites. Tergite 1 (IV) dorsally much longer than 2 (V) and 3 (VII) combined, lacking basal impression, with one pair of small mediobasal and one pair of larger basolateral foveae; discal carinae moderately long, subparallel posteriorly, extending posteriorly for slightly over half tergal length; 2–4 (VIII) successively shorter and narrower, each with one pair of small basolateral foveae; 5 (VIII) roundly trapezoidal, transverse, posterior margin slightly arcuate. Sternite 2 (IV) longest, with two pairs of basolateral foveae, 3–5 (V–VII) each short at middle, compact, 3 with one pair of small basolateral foveae, 4 (VI) and 5 lacking foveae, posterior margin of sternite 5 (VII) ( Fig. 8F ) with acute, hook-like expansion on left side (orientation according to figure), 6 (VIII) narrow, ring-like, 7 (IX) ( Fig. 8G ) composed of paired membranous lamellae, slightly sclerotized at apices.

AEDEAGUS ( Fig. 8H ) 0.30 mm long, dorso-ventrally asymmetric; median lobe with large, round and membranous basal capsule; left paramere wider and longer than right one, moderately broadened at apex, right paramere slightly curved, rounded at apex; endophallus armature composed of three to four small, blunt sclerotized spines at middle of posterior half of capsule.

Female

Unknown.

Remarks

The form of the modification of male sternite 5 (VII) and the aedeagus suggest a close relationship between this species and two congeners: T. punctifrons Löbl, Kurbatov & Nomura, 1998 distributed in south and southwest China (Chongqing, Shaanxi, Sichuan, Guangxi) ( Löbl et al. 1998) and T. tibialis Shen & Yin, 2015 occurring in eastern China (Zhejiang) ( Shen & Yin 2015). However, T. wumengmontis sp. nov. can be readily separated from both species by the lack of modifications on antennomere 11. While the simple antennomere 11 is shared with T. onerosus Löbl, Kurbatov & Nomura, 1998 found in Taiwan, eastern China, the male of T. onerosus has significantly more strongly thickened pro- and mesotibiae ( Löbl et al. 1998), along with a head and pronotum that are finely punctate, contrasting with the coarsely punctate features of T. wumengmontis . Previously, only one species of the genus, T. nabanhensis Shen & Yin, 2016 , has been known from Yunnan ( Shen & Yin 2016). The male of that species has modified antennomeres 11, widened protibiae, and completely different structures of sternite 5 (VII) and aedeagus.

Distribution

Southwest China: Yunnan.

Key to the species of the subfamily Pselaphinae Latreille, 1802 from the Wumenshan National Nature Reserve (males only)

1. Anterior margin of antennal scape with distinct notch at apex; parameres of aedeagus fused to ventral membranous plate, or reduced ........................................................................(Batrisitae: Batrisini ) 2

– Anterior margin of antennal scape straight, lacking distinct notch at apex; parameres of aedeagus present, fully developed .......................................... (Goniaceritae: Iniocyphini and Brachyglutini ) 7

2. Each elytron with three basal foveae; pronotal lateral margins spinose, or smooth (representing a rare case) .................................................................................................................................................. 3

– Each elytron with two or one basal foveae; pronotal lateral margins smooth, lacking spines ......... 4

3. Antennomere 10 and 11 greatly modified, 10 ( Fig. 6D ) with large cavity on ventral surface, and 11 ( Fig. 6C ) with broad basal projection; pronotal lateral margins ( Fig. 7B ) markedly protruding, with acute marginal spines; mesotibia ( Fig. 6F ) with distinct apical spine; aedeagus ( Fig. 6H–I ) stout ... ........................................................................................................... Tribasodites pectoralis sp. nov.

– Antennomere 10 and 11 ( Fig. 5C ) simple, unmodified; pronotal lateral margins ( Fig. 5B ) rounded, smooth, lacking marginal spines; mesotibia lacking apical spine; aedeagus ( Fig. 5F–G ) elongate ... ................................................................................................................ Tribasodites ocellus sp. nov.

4. Dorsal lobe of aedeagus ( Fig. 3G–I ) strongly twisted at base, recumbent .......................................... .............................................................................................................. Batrisiella ordinaria sp. nov.

– Dorsal lobe of aedeagus erect ........................................................................................................... 5

5. Abdomen modified, with central cavity on posterior half of tergite 1 (IV) ( Fig. 4E ); aedeagus with relatively small, constricted basal capsule ( Fig. 4G–H ) ......................... Batrisocenus asper sp. nov.

– Abdomen modified or unmodified, lacking central cavity on posterior half of tergite 1; aedeagus with relatively large, extended basal capsule ............................................................................................ 6

6 Dorsal surface of body ( Fig. 1A–B ) with scattered long, thick setae; head venter and prosternite unmodified; abdomen ( Fig. 1A, D ) modified, tergite 1 (IV) densely covered with anteriorly pointed setae ........................................................................................ Arthromelodes punctiventris sp. nov.

– Dorsal surface of body normally setose, lacking long, thick setae ( Fig. 2A ); head venter ( Fig. 2C–D ) with small lamellar-like protuberance at middle; prosternite ( Fig. 2E ) with deep, setose transverse sulcus; abdomen simple, lacking anteriorly pointed setae ..................... Arthromelodes weii sp. nov.

7 Head ( Fig. 7A ) greatly modified, with broad cavity on vertex; gular region lacking median carina; maxillary palpus short; pronotum ( Fig. 7B ) with transverse antebasal sulcus ................................... .......................................................................................................... Nipponobythus flamma sp. nov.

– Head ( Fig. 8A ) lacking modifications; gular region with broad median ridge; maxillary palpus markedly elongate; pronotum ( Fig. 8B ) lacking transverse antebasal sulcus .................................... .................................................................................................... Triomicrus wumengmontis sp. nov.

Figures

Fig. 8. Triomicrus wumengmontis sp. nov., holotype, ♂ (SNUC). A. Dorsal habitus. B. Head and pronotum. C. Antennal club. D. Protibia. E. Mesotibia. F. Sternite 5 (VII). G. Sternite 7 (IX). H. Aedeagus, ventral view. Scale bars: A = 0.5 mm; B = 0.3 mm; C–E = 0.2 mm; F, H = 0.1 mm; G = 0.05 mm.

Fig. 6. Tribasodites pectoralis sp. nov. A–I. Holotype, ♂ (SNUC). J. Paratype, ♀ (SNUC). A. Dorsal habitus. B. Head and pronotum. C. Antennal club. D. Antennomere 10, ventral view. E. Mesotrochanter. F. Mesotibia. 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, E–F = 0.2 mm; D, G–J = 0.1 mm.

Fig. 7. Nipponobythus flamma sp. nov., holotype, ♂ (SNUC). A. Dorsal habitus. B. Head and pronotum. C. Tergite 1 (IV). D. Sternite 6 (VIII). E. Sternite 7 (IX). F–G. Aedeagus, ventral views. Scale bars: A = 0.5 mm; B = 0.3 mm; C = 0.2 mm; D–G = 0.1 mm.

Fig. 5. Tribasodites ocellus sp. nov., holotype, ♂ (SNUC). A. Dorsal habitus. B. Head and pronotum. C. Antennal club. D. Mesotrochanter. E. Metatrochanter. F. Aedeagus, lateral view. G. Aedeagus, ventral view. Scale bars: A = 0.5 mm; B, D–E = 0.3 mm; C = 0.2 mm; F–G = 0.1 mm.

Fig. 3. Batrisiella ordinaria sp. nov., holotype, ♂ (SNUC). A. Dorsal habitus. B. Head and pronotum. C. Antennal club. D. Mesotrochanter. E. Mesotibia. F. Sternite 7 (IX). G. Aedeagus, anterior view. H. Aedeagus, lateral view. I. Aedeagus, ventral view. Scale bars: A = 0.5 mm; B, D = 0.3 mm; C, E = 0.2 mm; F = 0.05 mm; G–I = 0.1 mm.

Fig. 4. Batrisocenus asper sp. nov. A–H. Holotype, ♂ (SNUC). I. Paratype, ♀ (SNUC). A. Dorsal habitus. B. Head and pronotum. C. Protibia. D. Mesotibia. E. Tergite 1 (IV). F. Sternite 7 (IX). G. Aedeagus, lateral view. H. Aedeagus, ventral view. I. Genitalia, ventral view. Scale bars: A = 0.5 mm; B = 0.3 mm; C–E = 0.2 mm; F = 0.05 mm; G–I = 0.1 mm.

Fig. 1. Arthromelodes punctiventris sp. nov. A–G. Holotype, ♂ (SNUC). H. Paratype, ♀ (SNUC). A. Dorsal habitus. B. Head and pronotum. C. Protibia. D. Tergite 1 (IV). E. Sternite 7 (IX). F. Aedeagus, lateral view. G. Aedeagus, ventral view. H. Genitalia, ventral view. Scale bars: A = 0.5 mm; B = 0.3 mm; C–D = 0.2 mm; E = 0.05 mm; F–H = 0.1 mm.

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.