Genus Indonaia Prashad, 1918

(type species: Unio caeruleus Lea, 1831; by original designation) (Prashad 1918).

(Fig. 3A–H)

Comments: This genus contains 12 accepted species.Based on our new phylogenetic and morphological data, we consider Indonaia corbis (Hanley, 1856) stat. rev. as an accepted species endemic to the Brahmaputra River basin (Table 1; Fig. 3A–H). Additionally, two nominal species are transferred here from Indonaia to new genera (see below). Earlier, we separated three species groups in this genus: (i) the caerulea -group; (ii) the cylindrica -group; and (iii) the involuta -group (Bolotov et al. 2022a). Indonaia corbis belongs to the first group that is well resolved in both COI -based and combined phylogenies (Fig. 2; Supporting Information, Fig. S1). The cylindrica -group is supported by the COI phylogeny but is unresolved (non-monophyletic) in the three-locus combined tree. However, this group contains two Parreysia -like species that could be distinguished from other Indonaia species by having a thick, massive, ovate shell (Bolotov et al. 2022a) and seems to be a pair of sister-species rather than two unrelated taxa. This issue needs to be checked in the future using an expanded set of DNA markers.