Microichthyurus falcatus Y. Yang, Liu & X. Yang, 2025

Lin, Hanqing, Liu, Haoyu, Yang, Xingke & Yang, Yuxia, 2025, Taxonomy of the genus Microichthyurus Pic (Coleoptera, Cantharidae, Chauliognathinae), with descriptions of nine new species from China, Deutsche Entomologische Zeitschrift 72 (1), pp. 27-56 : 27-56

Microichthyurus falcatus Y. Yang, Liu & X. Yang sp. nov.

Figs 1 C, D , 2 C, D , 3 B , 4 E ‒ H , 5 C, D

Etymology.

The specific name is derived from the Latin falcatus (sickle-shaped, hooked, curved), referring to its median lobe of aedeagus with a horn-shaped protrusion.

Type material.

Holotype. China ‒ Yunnan Prov. • ♂; Mangshi ; 900 m; 19-V-1955; Popov leg.; IZAS.

Paratypes. China ‒ Yunnan Prov. • 2 ♀♀; same data as holotype; IZAS • 1 ♂ 1 ♀; Longling ; 1600 m; 19-V-1955; Busik & L. Wu. leg.; IZAS • 1 ♀; Longling ; 1600 m; 19-V-1955; Popov leg.; IZAS • 1 ♂; Longling ; 1200 m; 19-V-1955; Krebolanovsky leg.; IZAS • 1 ♀; Jingdong ; 900 m; 31-V-1956; Popov leg.; IZAS .

Diagnosis.

The species resembles M. flavicollis Y. Yang, Liu & X. Yang, 2024 , in the general shape of male abdominal sternite VIII and aedeagus, but can be easily distinguished from the latter by the following characters: pronotum dark brown (Fig. 1 C ‒ D ); abdominal sternite VIII of male (Fig. 2 D ) with lateral portions acute at latero-apical angles; median lobe of aedeagus ( Lin et al. 2024 a: fig. 2 a, b) present with a horn-shaped protrusion (Fig. 4 E, H ). Unlike in M. flavicollis , pronotum is uniformly yellow; abdominal sternite VIII of male ( Lin et al. 2024 a: fig. 3 a) is rounded at latero-apical angles; median lobe of aedeagus ( Lin et al. 2024 a: fig. 6 a) is present with a fork-shaped protrusion.

Description.

Body length (both sexes): 4.9‒6.8 mm (6.8 mm in holotype); body width (both sexes): 1.0‒ 1.6 mm (1.6 mm in holotype).

Male (Fig. 1 C ). Coloration. Body black, but yellow at antennomeres I ‒ II, coxae, trochanters, and bases of femora and apical parts of elytra, forming a pair of triangular yellow areas, as well as lateral margins of abdominal ventrites II ‒ VI.

Eyes large, interocular distance about half as wide as diameter of an eye. Antennae extending to posterior margin of abdominal tergite II, antennomeres II about 1 / 3 length of I, III ‒ XI subequal in length and about twice longer than II.

Pronotum 1.1 times wider than long, anterior margin arcuate, posterior margin slightly bisinuate, lateral margins subparallel, anterior angles rounded, and posterior angles nearly rectangular. Elytra 1.3 times longer than wide, 1.8 times longer than pronotum, with lateral margins sinuate, sutures slightly dehiscent from posterior 2 / 3 part, distance between sutures slightly wider than width of the elytron, apices rounded.

Abdominal tergite VIII (Fig. 2 C ) as long as wide, with lateral margins moderately arcuate, postero-lateral projections about 1 / 4 length of the tergite and straight at inner margins. Abdominal sternite VIII (Fig. 2 D ) trilobed, with lateral portions nearly inverted triangular, as long as wide, inner and outer apical angles sharply projecting, each with an obtuse tooth at posterior margin; middle portion about 1.5 times as long as wide, feebly narrowed posteriorly, nearly straight at posterior margin, and acute and feebly projecting at latero-apical angles. Proctiger (Fig. 3 B ) semicircular, slightly exceeding over paraproct, covered with short pubescence on surface. Paraproct (Fig. 3 B ) twice wider than proctiger and feebly narrowed posteriorly, covered with slightly long pubescence along posterior margin, with tergal flange long and almost 4.0 times as long as paraproct, basal 2 / 5 part strongly broadened and subquadrate, which heart-shapely convex near outer apical angles, apical 3 / 5 part slender and bent inwards.

Aedeagus (Fig. 4 E ‒ H ): left ventral paramere rod-like, progressively thinned apically and feebly hooked at apex, moderately sinuate (Fig. 4 F, H ); left dorsal paramere about 1.1 times longer than left ventral paramere, rod-like, progressively thinned apically and rounded at apex, feebly sinuate (Fig. 4 F, H ); right paramere nearly as long as left ventral paramere (Fig. 4 F, G ), abruptly thinned near apex and sharply hooked at apex (Fig. 4 E, H ); median lobe strongly sclerotized, about 1.2 times longer than parameres, grooved at basal part, long cone-shaped at apical half, rounded at apex, present with a strongly sclerotized and horn-shaped protrusion on ventro-lateral part (Fig. 4 E, H ).

Female (Fig. 1 D ). Similar to males, but body larger. Abdominal tergite VIII (Fig. 5 C ) about 1.2 times longer than wide, with lateral margins arcuate at base, lateral projections about 1 / 4 length of the tergite, and slightly sinuate at inner margins. Abdominal sternite VIII (Fig. 5 D ) about 1.2 times longer than wide, with lateral margins moderately converging posteriorly, posterior margin concave in middle, and latero-apical angles rounded.

Distribution.

China (Yunnan).

Figures

Figure 1. Habitus of Microichthyurus, dorsal views. A ‒ B. M. robusticeps Pic, 1923; C ‒ D. M. falcatus sp. nov. A, C. holotype males; B, D. paratype females. Scale bars: 2.0 mm.

Figure 2. A ‒ B. M. robusticeps Pic, 1923; C ‒ D. M. falcatus sp. nov. A, C. male abdominal tergite VIII, ventral view; B, D. male abdominal sternite VIII, ventral view. Scale bars: 0.2 mm.

Figure 3. Proctiger and paraproct of Microichthyurus species, ventral views. A. M. robusticeps Pic, 1923; B. M. falcatus sp. nov. Abbreviations: p – proctiger; pp – paraproct; tf – tergal flange. Scale bars: 0.2 mm.

Figure 4. Aedeagi of Microichthyurus species. A ‒ D. M. robusticeps Pic, 1923; E ‒ H. M. falcatus sp. nov. A, E. ventral views; B, F. right-lateral views; C, G. left-lateral views; D, H. dorsal views. Abbreviations: ldp – left dorsal paramere; lvp – left ventral paramere; rp – right paramere; ml – median lobe. Scale bars: 0.2 mm.

Figure 5. A ‒ B. Microichthyurus robusticeps Pic, 1923; C ‒ D. M. falcatus sp. nov. A, C. female abdominal tergite VIII, ventral view; B, D. female abdominal sternite VIII, ventral view. Scale bars: 0.2 mm.