Trisiniotus jiulong Zhang, Wei & Yin, 2024

Zhang, Yong-Qin, Wei, Guo-Hao & Yin, Zi-Wei, 2024, Two new species of ant-loving beetles (Coleoptera: Staphylinidae: Pselaphinae) from Jiulong National Wetland Park, China, Zootaxa 5406 (2), pp. 336-342 : 337-339

Trisiniotus jiulong Zhang, Wei & Yin , sp. nov.

( Figs 1 , 3 )

Chinese common name: 九AEDz沟Dzm

Type material (10 exx.). HOLOTYPE: CHINA: ♂: ‘China: Zhejiang, Lishui, Jiulong National Wetland Park , 28°23’4.86”N, 119°49’29.15”E, 50 m, 22.ix.2023, fern leaves, Zhang, Wei, Ming & Jia leg. (浙江丽水九AE国NJae 地公园)’ ( SNUC) . PARATYPES: CHINA: 1 ♂, 1 ♀, same collecting data as for holotype; 4 ♀♀, same collecting data as for holotype, except ‘23.ix.23’ (浙江丽水九AE国NJae地公园)’; 1 ♂, 2 ♀♀, ‘China: Zhejiang, Lishui, Bihu To. Hongyu Vill., Jiulong Wetland Park , 28°23’6”N, 119°49’29”E, 50 m, 2.vi.2023, riverbank, sifted, Z-W. Yin leg. (丽水九AE国NJae地公园河岸®丛)’ (1 ♂, 1 ♀ in IZCAS, others in SNUC) .

Diagnosis. Male. Body length approximately 2.0 mm. Head sub-rectangular at base; vertex finely punctate, with short, transverse sulcus at anterior portion; antenna elongate; antennomeres more or less elongate, lacking obvious modifications, antennomere 10 moderately swollen and distinctly longer than 9. Pronotum lacking median longitudinal sulcus, with smooth disc, basal color roughened. Discal striae of elytra extending posteriorly to approximately apical 3/4 of elytral length. Metaventrite with pair of admesal denticulate projections. Mesotibia with moderately long apical spine. Tergite 1 (IV) predominantly large, dorsally longer than 2–4 (V–VII) combined, lacking modifications. Aedeagus strongly asymmetric; median lobe with restricted basal capsule and subtriangular foramen, ventral stalk slightly shorter than dorsal lobe, narrowed at apex. Female. Body length approximately 1.8 mm, legs and metaventrite lacking modifications, genitalia as in Fig. 1G .

Description. Male. Body ( Fig. 1A ) length 1.90–2.01 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface finely punctate, covered with short pubescence.

Head ( Fig. 1B ) sub-rectangular, truncate at base, slightly wider than long, length 0.38–0.40 mm, width across eyes 0.42–0.45 mm; vertex finely punctate, with moderately separated foveae (dorsal tentorial pits), with short, transverse sulcus at apical portion of vertex; tempora much shorter than eyes, convergent posteriorly; lacking mediobasal carina; antennal tubercles weakly raised; frons slightly impressed medially, confluent with clypeus; clypeus smooth, its anterior margin carinate and moderately raised; ocular-mandibular carinae complete, distinct. Venter with small gular foveae (posterior tentorial pits) in single pit, with distinct median carina extending from foveae anteriorly to mouthparts. Eyes greatly prominent, each composed of approximately 29–35 ommatidia. Maxillary palpus with palpomere 1 minute, 2 elongate, curved, pedunculate basally and enlarged apically, 3 short, sub-trapezoidal, 4 fusiform, widest near middle. Antenna moderately elongate, length 0.81–0.93 mm; club loosely formed by enlarged apical three antennomeres ( Fig. 1C ); antennomere 1 thick, subcylindrical, 2–7 each elongate, successively longer, 8 shortest, 9 much longer and broader than 8, 10 longer than 9, 11 longest, slightly shorter than (21:25), sub-conical.

Pronotum ( Fig. 1B ) almost as long as wide, length 0.43–0.46 mm, width 0.42–0.45 mm, widest at middle; semi-circular lateral sulci extending from dorsal surface laterally and posteriorly and then fused with lateral ends of antebasal sulcus; disc moderately convex, finely punctate, median longitudinal sulcus absent, lacking median antebasal fovea, with short mediobasal impression, lateral antebasal foveae connected by transverse antebasal sulcus. Prosternum with anterior part slightly shorter than coxal part, with small lateral procoxal foveae; hypomeral grooves short, present only on basal halves, lacking lateral antebasal hypomeral impression; hypomeral ridges close to coxal cavities.

Elytra much wider than long, length 0.61–0.66 mm, width 0.70–0.76 mm; suboval, dorsal surface with dense, short pubescence; each elytron with two large, asetose, basal foveae; discal striae long, extending from outer basal foveae posteriorly to 7.6/10 of elytral length; humeral region moderately raised, subhumeral fovea absent, with sulcate marginal stria extending from approximately middle to posterior margin. Metathoracic wings fully developed.

Mesoventrite short, demarcated from metaventrite by ridged anterior edges of impressed areas where lateral mesocoxal foveae situated at mesal ends of impressions, with pair of admesal carinae; median mesoventral foveae widely separated, originating from shared setose, transverse opening, lateral mesoventral foveae large and setose, broadly forked internally, with short intercoxal process. Metaventrite finely punctate, broadly impressed at middle, lateral margin of impression with pair of denticulate projections; with large, setose lateral mesocoxal foveae and pair of smaller, setose lateral metaventral foveae, posterior margin with small and narrow split at middle.

Legs moderately elongate; protibia slightly arcuate; mesotibia with distinct spine at apex ( Fig. 1D ); mesofemur widened to middle; each tarsus with one major and one reduced setiform pretarsal claw.

Abdomen widest at lateral margins of tergite 1 (IV), length 0.78– 0.82 mm, width 0.62–0.66 mm. Tergite 1 (IV) in dorsal view longer than 2–4 (V–VII) combined, with inner basolateral foveae embracing thin sulcus and pair of outer basolateral foveae, short, triangular discal carinae present; tergites 2 (V) and 3 (VI) lacking foveae and sulcus, 4 (VII) with pair of small basolateral foveae, slightly shorter than 2 (V) and 3 (VI) combined along middle; tergite 5 (VIII) semicircular, posterior margin narrowly and deeply emarginate at middle. Sternite 2 (IV) with mediobasal and basolateral foveae; midlength of sternite 2 approximately as long as 3–4 (V–VI) combined, 3 and 4 each short at middle, combined approximately longer than 5 (VII), 3–5 (V–VII) lacking foveae, 6 (VIII) transverse, posterior margin convex at middle.

Aedeagus ( Fig. 1E, F ) 0.29 mm in length, moderately sclerotized, dorso-ventrally strongly asymmetric; median lobe with restricted basal capsule and small, subtriangular foramen, ventral stalk elongate, widest at approximately apical 1/4 and then tapering apically; dorsal lobe broadened at base, narrowing towards apex; parameres fused and reduced to ventral membrane.

Female. General external morphology similar to male; antennomeres simple; each eye composed of about 28–30 ommatidia; humeri flat; metathoracic wings reduced. Measurements (as for male): body length 1.80–1.83 mm, length/width of head 0.37–0.38 mm / 0.44 mm, length/width of pronotum 0.43–0.46 mm / 0.42–0.44 mm, length/ width of elytra 0.58–0.59 mm / 0.71–0.73 mm, length/width of abdomen 0.52–0.56 mm / 0.64–0.67 mm; length of antenna 0.82–0.92 mm; genital complex ( Fig. 1G ) 0.22 mm wide, genital plate approximately as wide as sternite 7 (IX), with lateral arms slender and narrowing apically.

Comparative notes. The male of this species is most similar to Trisiniotus taoismus Feng & Yin , distributed in Jiangsu, eastern China by the simple male antennomeres 10. They can be separated by antennomeres 10 being distinctly longer than 9 (as long as 9 in T. taoismus ), a finely punctate pronotum (pronotum with much more distinct punctures in T. taoismus ), much larger apical spines of the mesotibiae, and a different aedeagus. Within the genus, T. taoismus is the only other species that has the female genital complex illustrated ( Feng & Yin 2022: fig. 1F). The genital complex ( Fig. 1G ) of T. jiulong sp. nov. is less transverse, and the lateral arms of the genital plate are relatively much slenderer than those of T. taoismus .

Biology. All individuals were collected from sifted fern leaf samples along or near the riverbank ( Fig. 3 ).

Distribution. Eastern China: Zhejiang.

Etymology. The name is a noun in apposition, taken from the type locality of the new species, i.e., Jiulong National Wetland Park.

Figures

FIGURE 1. Morphology of Trisiniotus jiulong sp. nov. (A–F Male. G. Female). A. Dorsal habitus. B. Head and pronotum. C. Antennal club. D. Apex of mesotibia. E, F. Aedeagus, lateral (E), and ventral (F). G. Genital complex. Scale bars: 0.5 mm in A; 0.3 mm in B; 0.2 mm in C; 0.05 mm in D; 0.1 mm in E–G.

FIGURE 3. Habitat of Trisiniotus jiulong sp. nov. and Arthromelodes lianghongbini sp. nov. along (A) and near (B) riverbank.