Male genitalia of four morphospecies A–D type mA, Biasticus taynguyenensis Ha, Truong & Ishikawa, sp. nov., paratype, ♂, TXL2016-545 E–I type mB, B. griseocapillus Ha, Truong & Ishikawa, sp. nov., paratype, ♂, TXL2016-546 J–N type mC, B. luteicollis Ha, Truong & Ishikawa, sp. nov., holotype, ♂, HNL2018-025 O–R mF, B. flavus (Distant, 1903), ♂, HEM-TH2004-018. A, E, J, O pygophore with paramere(s) in dorsal view B, F, K, P phallus in dorsal view C, G, L, Q phallus in lateral view D, I, N, R articulatory apparatus H, M distal dorsal lobe of endosoma.