Sinonychus lipinae Jiang & Chen, 2025

Jiang, Ri-Xin & Chen, Xiang-Sheng, 2025, Two new species of the genus Sinonychus (Coleoptera, Elmidae) from Guizhou, China, ZooKeys 1223, pp. 57-67 : 57-67

Sinonychus lipinae Jiang & Chen sp. nov.

Figs 1 A, C , 2 A – F , 4 A – G (李氏华溪泥甲 )

Type material.

26 exs: 11 ♂♂, 5 ♀♀, 10 exs., sex undetermined. Holotype: • China: ♂, labeled “ China: Guizhou, Qiannan Buyi and Miao Autonomous Prefecture (黔南布依族苗族自治州), Longli (龙里县), Wantanhe Town (湾滩河镇), H: 1136.10 ± 1.08 m, 26°12'52"N 106°59'27"E, 31. VIII. 2023, Jiang Ri-Xin, Hai-Tao Li, Pin Li, Yu-Hao Zhang, Yin-Lin Mu & Xiu-Dong Huang leg. ” ( GUGC) . Paratypes: • 10 ♂♂, 5 ♀♀, 10 exs., sex undetermined, with same label data as the holotype ( GUGC) .

Diagnosis.

Body broadly oval, black; mouthparts, antennae, anterior margin of pronotum, trochanters and base of tibia and tarsi (including claws) light brown. Frons, pronotum and basal elytra finely granulate. Pronotum with anterolateral marginal band of silvery, sericeous tomentum. Elytral intervals 3, 5, 6, 7 with granulate carinae; carina of interval 3 short, less than half the length of elytron; other carinae longer than half length of elytron. Aedeagus slender, apex of median lobe acute; median lobe with a pair of long sclerotizations located at apical 1 / 2.

Description.

Body broadly oval (Fig. 1 A ); black, with mouthparts, antennae, anterior margin of pronotum, trochanters and base of tibia and tarsi (including claws) light brown. Plastron setae confined to the following areas: head (both dorsal and ventral surfaces, including clypeus); pronotum (anterolateral marginal areas); elytra (lateral areas, including epipleura); prosternum (except disc); mesoventrite, metaventrite and abdomen (lateral areas); and femora.

Head (Fig. 2 A ) wider than long, surface covered with plastron setae and mixed with sparse, long setae and granules. Clypeus anterior surface microreticulate; covered with sparse, long setae; without plastron setae. Labrum transverse, narrower than clypeus; surface microreticulate, apical 1 / 2 covered with sparse, long setae; apical margin nearly straight; lateral margins rounded and with long bristles. Antenna (Fig. 1 C ) 7 - segmented with apical antennomere clubbed.

Pronotum (Fig. 2 B ) wider than long, widest at base, get narrowed from basal 1 / 3 to apex. Surface microreticulate and granulate except areas near apical margin. Apicolateral margins covered with plastron setae. Anterior 1 / 2 of disc covered with sparse, long setae distinctly longer than setae on other parts of pronotum. Median longitudinal sulcus distinct and long, extending from base nearly to anterior margin, deep at basal 1 / 2, much shallower at apical 1 / 2. Sublateral grooves distinct and straight, parallel to each other. Anterior margin strongly curved, anterior angles not produced. Lateral margins nearly parallel at base, then evenly narrowed. Basal margin trisinuate, emarginate anterior to scutellum, posterior angles nearly orthogonal. Prosternal process (Fig. 2 C ) subtriangular, with rounded apex, surface distinctly microreticulate, covered with sparse, long setae.

Scutellum (Fig. 2 B ) cordate, longer than wide, widest at basal 1 / 3; surface shiny and glabrous. Anterior margin strongly curved, lateral margins weakly curved, apex acutangular.

Elytra (Fig. 2 F ) longer than wide, widest near middle. Surface granulate near base and apex; disc microreticulate. Strial punctures large in basal 2 / 3 of elytra, mostly separated by about twice a diameter; much smaller and widely separated in other parts of elytra. Elytral intervals 3, 5, 6, 7 with granulate carinae; carina of interval 3 shortest, about 1 / 3 length of elytra; carina of interval 5 about 2 / 3 length of elytra; other two carinae long, extending from base of elytra nearly to apex. Areas from interval 5 to lateral margins with plastron setae except for apical 2 / 3 between intervals 5 and 6. Hing wings reduced.

Metaventrite (Fig. 2 D ) with disc distinctly microreticulate and covered with sparse, long setae; lateral areas with plastron setae. Median sulcus shallow and indistinct, extending from posterior margin to anterior margin.

Abdominal surface finely granulate (Fig. 2 E ). Admedian carinae of ventrite 1 obscure, straight, extending from base to apex. Median areas of ventrites 1–4 and anterior middle part of ventrite 5 distinctly microreticulate; lateral areas of ventrites 1–5 covered with plastron setae and mixed with sparse long setae.

Legs simple, surface granulate (except tarsi). Surface of femora covered with sericeous tomentum; inner side of tibiae with cleaning fringes; tarsi slightly shorter tibiae; tarsal claws simple.

Aedeagus (Fig. 4 A – D ) slender and elongate. Parameres short, not obvious, weakly sclerotized, without setae. Median lobe symmetrical, distinctly narrowed near base; apex acute; with a pair of long sclerotizations at apical 1 / 2. Sternite IX (Fig. 4 E ) with apical margin curved, without setae, median strut with base distinctly curved. Phallobase short, about 1 / 6 length of median lobe.

Measurements: CL: 1.25–1.43 mm; PL: 0.42–0.50 mm, PW: 0.58–0.63 mm; EL: 0.81–0.93 mm, EW: 0.70–0.75 mm.

Female externally similar to the male, but averaging larger. Ovipositor as in Fig. 4 F, G : valvifer about twice as long as coxite, distinctly expanded at base; coxite apex strongly expanded, broadly rounded at outer margin; stylus short, distinctly curved at middle.

Measurements: CL: 1.28–1.41 mm; PL: 0.43–0.48 mm, PW: 0.61–0.66 mm; EL: 0.85–0.93 mm, EW: 0.73–0.81 mm.

Distribution.

China. Only known from the type locality in Longli County, Qiannan Buyi and Miao Autonomous Prefecture, Guizhou Province.

Biology.

All adults were collected from gravel on the bottom of a small stream in a ravine (Fig. 5 A – E ).

Etymology.

The species epithet “ lipinae ” honors our friend and colleague Dr Pin Li (Guizhou University), one of the collectors of this new species.

Comparative diagnosis.

Sinonychus lipinae sp. nov. is highly similar to the Japanese species S. tsujunensis in appearance. The new species can be distinguished from the latter species by the following characters: 1) median longitudinal sulcus of pronotum narrower; basal 1 / 2 distinctly wider than apical 1 / 2 (vs. much wider; basal 1 / 2 weakly wider than apical 1 / 2); 2) male aedeagus with apex of median lobe acute (vs. apex rounded); 3) parameres without setae in basal parts (vs. bearing short setae in basal parts); and 4) median lobe about 6 times as long as phallobase (vs. about 5 times as long as phallobase).

Figures

Figure 1. A dorsal habitus of Sinonychus lipinae sp. nov. B dorsal habitus of S. luodianensis sp. nov. C antenna of S. lipinae sp. nov. D antenna of S. luodianensis sp. nov. Scale bars: 0.5 mm (A, B); 0.05 mm (C, D).

Figure 2. Diagnostic features of Sinonychus lipinae sp. nov. A head B pronotum C prosternal process D metaventrite E abdomen F elytron. Scale bars: 0.1 mm (A); 0.2 mm (B – F).

Figure 4. Genital features of Sinonychus species: A – G Sinonychus lipinae sp. nov. H – N, Sinonychus luodianensis sp. nov. A, H aedeagus, dorsal view B, J ditto, ventral C, I ditto, median lobe D, K ditto lateral view E, L sternite IX F, M ovipositor G, N ditto, apical part. Scale bars: 0.05 mm (G, N); 0.1 mm (A – F, H – M).

Figure 5. Habitat of Sinonychus lipinae sp. nov. at the type locality A general environment B microenvironment C living adult D collectors, left: Miss Yu-Hao Zhang, right: Dr Yin-Lin Mu E collectors, left: Dr Hai-Tao Li, right: Dr Pin Li.