Trigonidium albarum Ma, Yuan & Gu, 2025

Trigonidium albarum Ma, Yuan & Gu sp. nov.

Chinese name: ƦỄÜḃ

( Figs. 1 View FIGURE 1 , 2 View FIGURE 2 , 3 View FIGURE 3 )

Type materials. Holotype. China: male, Guancunzi, Ningnan , Sichuan, 1-Ⅴ-2023, Yuan, Wei, Zheng, Chengjie coll. ( SICAU) . Paratypes. China: 4♂♂ 5♀♀, Guancunzi, Ningnan , Sichuan, 1- Ⅴ -2023, Yuan, Wei, Zheng , Chengjie coll. ( SICAU) ; 1♂ 1♀, Guancunzi, Ningnan , Sichuan, 1- Ⅴ -2023, Yuan, Wei, Zheng , Chengjie coll. ( IZCAS) ; 2♂ 1♀, Huaguoshan, Xiangyun , Yunnan, 19-VII-2024, Yuan, Wei coll. ( SNNU) .

Etymology. The specific epithet is from the Latin ‘ albarum ’, means white dorsal area of the forewings of this species.

Diagnosis. Metafemur with dark coloration of the upper part and light coloration of the lower part ( Fig. 2 A, B View FIGURE 2 ); tegmina with light dorsal area and dark lateral area ( Fig. 1 View FIGURE 1 ), compound eyes black.

Description. Male ( Figs. 1A View FIGURE 1 , 2A View FIGURE 2 ): Body small, slender; profemur, mesofemur and abdomen black; protibia, mesotibia and most part of metatibia with light color; tegmina mostly light, lateral area dark. Vertex wide and flat, with sparsely setae; frontal wide, not protruding in the dorsal view, slightly wider than antennal scape; compound eyes large, not protruding in the dorsal view; ocellus present, with compound eyes linked by two light stripes; antennal scape broad, cylindrical, flagellum longer than body length; clypeus wide, oval; maxillary palp five segments, terminal segment with obtuse end; labial palpi three segments, the terminal segment enlarged with obtuse end. Pronotum trapezoidal, posterior margin slightly wider than the anterior; anterior, posterior and lateral margins with long setae; the median area of disc with dark marks, lateral area with light marks; lateral lobe mostly black. Procoxa cylindrical with sparsely setae; profemur and protibia covered with hairs; profemur ventral margin with two distinct ridges; tympana absent, protibia terminal with one, slender apical spur; probasitarsus covered abundant short setae; second tarsomeres flattened; third tarsomere shorter than basitarsus, with two curved, serrated claws. Mesofemur and mesotibia covered with small hairs; mesotibia with two apical spurs; tarsus is similar to the prothoracic leg. Metatibia with six subapical spurs (inner three and outer three) and five apical spurs (inner two and outer three), inner longer than outer spur; metabasitarsi not serrulated, with abundant short setae on ventral, apical with one inner and one outer spur, second tarsomeres short, third tarsomere with two curved and serrated claws. Tegmina present and developed, lateral field narrow, with few branches of Sc; R, M+CuA, CuP, PCuA, PCuP, AA and AP neither fused nor branched, without prominent cross-veins between the main veins. Genitalia ( Fig. 3 View FIGURE 3 ). In dorsal view, epiphallus broadened, inner margin of lateral lobe concave, serrated, tapering at the end; in lateral view, lateral lobe with obtuse end, ectoparamere invisible, protrude slightly; in ventral view, ectoparamere short and bifurcated, with straight lower branch.

Female ( Figs. 1B View FIGURE 1 , 2B View FIGURE 2 ). Similar to males, tegmina only with longitudinal veins. Ovipositor sword-shaped.

Measurements. Male (n=2). BL 5.21±0.34, PL 0.92±0.10, TL 2.35±0.24, HFL 3.16±0.11; Female (n=2). BL 6.12±0.31, PL 0.85±0.06, TL 2.74±0.23, MFL 4.98±0.11 OL 0.43±0.10.

Remarks. Based on the absent of tympana, similar vein patterns of wings in both sexes, and developed and bifurcated ectoparamere, this new species can be assigned to Trigonidium . The new species shares similar features of epiphallus (broad, concave, serrated lateral lobe, and tapering at the end) and ectoparamere (short and bifurcated) with Trigonidium cicindeloides Rambur, 1838 , Trigonidium nigripes Yuan, Ma & Gu, 2022 , and Trigonidium japonicum Ichikawa, 2001 , but new species with narrower lateral lobe in lateral view, and can be distinguished from these species by the coloration (colored dark of profemur, mesofemur, and abdomen; colored light of protibia and mesotibia; and colored dark and light of metafemur). The new species shares similar coloration (black profemur, mesofemur and abdomen, light protibia, mesotibia and most part of metatibia, and the tegmina dorsal area mostly white, lateral area black) with Trigonidium rubrumoculum He & Ma, 2022 , but T. rubrumoculum has different ectoparamere possessing long and thin upper branch and epiphallic lateral lobe not serrated of its inner margin, and T. rubrumoculum has red compound eyes.