Indonaia Prashad, 1918

Bolotov, Ivan N., Sonowal, Jyotish, Kardong, Devid, Pasupuleti, Rajeev, Subba Rao, Nalluri V., Unnikrishnan, Suresh Kumar, Gofarov, Mikhail Y., Kondakov, Alexander V., Konopleva, Ekaterina S., Lyubas, Artem A. & Vikhrev, Ilya V., 2024, Discovery of an endemism hotspot of freshwater mussels (Bivalvia: Unionidae) in Assam, with a description of two new genera, Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) 202 (4), pp. 1-19 : 6

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.

Figures

Figure 1. Map of the Indian subcontinent with location of the study region (the frame) (A) and enlarged map of the study region in northeastern India (B). Assam is indicated by green filling (A) and cross-hatching (B). Green circles with numbers indicate the sampling localities in Assam:Burhidihing River, Dibrugarh (1); Gelua River, Dhemaji (2); an oxbow lake of Dhansiri River, Golaghat (3); old channel/pond, Telam River basin, Telam, Dhemaji (4); an oxbow lake of Tongani River (Tongani beel), Dhemaji (5); Dhansiri River, Golaghat (6); Sesa River, Dibrugarh (7); and a pond, Sutar Gaon, Kamrup (Rural) District (8). The maps were created using ESRI ArcGIS 10 software (www.esri. com/arcgis); the topographic base of the maps was created with Natural Earth Free Vector and Raster Map Data (www.naturalearthdata.com), Global Self-consistent Hierarchical High-resolution Geography (https://www.soest.hawaii.edu/wessel/gshhg), GEBCO_2022 (https://www. gebco.net/data_and_products/historical_data_sets/#gebco_2022), and Global Edge-matched Subnational Boundaries (https://fieldmaps. io). Maps: Mikhail Yu. Gofarov.

Figure 2. Maximum likelihood (IQ-TREE v.1.6.12) phylogeny of the Parreysiinae based on the combined alignment of the two mitochondrial and one nuclear gene fragments (three codons of COI + 16S rRNA + 28S rRNA). The labels of species recorded from Assam (Brahmaputra River basin) are red.The scale bar indicates the branch lengths.The information on DNA sequences is presented in the Supporting Information, Dataset S2. Outgroup taxa are not shown.

Figure 3. Shells of Indochinellini species from Assam (outer view of the left valve and inner view of the right valve).(A–H) Indonaia corbis (Hanley, 1856) stat. rev.: topotypes IX-BDH-1 (A), IS-TLM-3 (B), IA-GEL-5 (C), X2-SES (D), X1-SES (E), I2-SES-2 (F), TZ-BDH-2 (G); holotype of Trapezoideus dhanushori Annandale and Prashad, 1921 with its labels (ZSI M11962/2), Dhanushori Stream at a distance of about a mile from Dimapur, Assam (H). (I–K) Pseudoscabies scobina (Hanley, 1856) gen.et comb. nov.: topotypes SC-SES-1 (I), IO-BDH-5 (J), and IO-BDH-4 (K). Scale bars = 10 mm. The shell vouchers of the new samples are deposited in FBRC ZSI (Supporting Information, Dataset S1). Photos: J. Sonowal and D. Kardong (A–G, I–K); A.Mukhopadhyaya and S. Sajan (H).