Blacus (Ganychorus) castaneus, Lu & Chai & Achterberg & Tang & Chen, 2025

Blacus (Ganychorus) castaneus sp. nov.

( Figs 5–6 View FIGURE 5 View FIGURE 6 )

Material examined. Holotype: ♀, China, Yunnan, Xishuangbanna, Forest Park , 31.VII.2003, Xu Zaifu, No. 20053493 ( ZJUH).

Diagnosis. The new species is similar to B. (G.) obscuripes van Achterberg, 1988 because it shares the sparsely setose frons, whole hind femur dark brown, first discal cell of fore wing truncate anteriorly, middle claws with blackish bristles, propodeum smooth, length of first tergite approx. 2.5 × its apical width, notauli only crenulate anteriorly, propodeal tubercles present, and propodeum without areola, but differs by having yellow subapical antennomeres (whole antenna dark brown in B. (G.) obscuripes ), base of second tergite with short oblique sculpture laterally (smooth), length of hind tibia 12.3 × its width (10.5 ×), precoxal sulcus complete, wide and striate-rugose (absent anteriorly and sparsely sculptured posteriorly), and length of malar space 1.6 × basal width of mandible (1.2 ×).

This new species is also similar to B. (G.) longitergitus sp. nov., because of the short oblique sculpture at base of second tergite, length of ovipositor sheath approx. 0.20 × length of fore wing, first metasomal tergite slender and length of first tergite 2.5 × its apical width, but differs by having narrow notauli that are smooth posteriorly (wide and rugose posteriorly in B. (G.) longitergitus sp. nov.), frons sparsely setose (more densely setose), area between dorsal carinae of first tergite smooth (reticulate-rugose), propodeum smooth between carinae (rugose), and hind femur and tibia brown (pale yellow).

Description. Female. Length of body 2.5 mm, length of fore wing 2.35 mm.

Head. Antennomeres 20 ( Fig. 6C View FIGURE 6 ); length of first flagellomere 1.25 × length of second flagellomere; length of first, second and penultimate flagellomere 5.7, 4.6 and 2.1 × their width, respectively; length of maxillary palp 1.1 × height of head; occipital carina complete; frons smooth and sparsely setose, frontal suture present; OOL: OD: POL = 9: 4: 5; length of eye in dorsal view 1.3 × length of temple; face with weak transverse rugae; malar suture present, length of malar space 1.6 × basal width of mandible.

Mesosoma. Length of mesosoma 1.5 × its height; side of pronotum smooth dorsally, rugose ventrally; whole mesopleuron with long sculpture ( Fig. 6F View FIGURE 6 ); precoxal sulcus wide and striate-rugose; notauli narrow, crenulate anteriorly and smooth posteriorly ( Fig. 6D View FIGURE 6 ); area near notauli setose; scutellum smooth, protruding dorsally; propodeal tubercles absent; surface of propodeum between carinae smooth, carinae lamelliform, medial area absent ( Fig. 6E View FIGURE 6 ).

Wings. Fore wing: first discal cell rather widely truncate anteriorly; 1-CU1: 2-CU1 = 9: 17 ( Fig. 6K View FIGURE 6 ).

Legs. Hind coxa with several carinae dorsally; length of femur, tibia and basitarsus of hind leg 6.5, 12.3 and 11.7 × their width, respectively; fore and middle claws with blackish bristles, hind claws simple.

Metasoma. Length of first tergite 2.5 × its apical width, slender and slightly widened apically, smooth between the dorsal carinae, remainder of tergite longitudinally rugose ( Fig. 6H View FIGURE 6 ); base of second tergite with short oblique sculpture laterally ( Fig. 6I View FIGURE 6 ); length of ovipositor sheath 0.21 × length of fore wing.

Colour. Brown; several subapical antennomeres, palpi, fore leg, middle coxa and 2-5 th hind tarsal segments yellow; basal half of metasoma ventrally pale yellow and subhyaline; wing membrane infuscated.

Male. Unknown.

Biology. Unknown.

Distribution. China (Yunnan).

Etymology. “ Castaneus ” is Latin for brown and refers to the brown colour of the body.