taxonID	type	description	language	source
5FDEEB171FA05F25A9FA0D099E66D316.taxon	type_taxon	Type species. Songkhlanaia tamodienica Konopleva, Lheknim, Sriwoon, Kondakov, Vikhrev & Bolotov in Konopleva et al. 2023 (by original designation).	en	Jeratthitikul, Ekgachai, Sutcharit, Chirasak, Prasankok, Pongpun (2025): An integrative approach to a revision of the freshwater mussel genus Songkhlanaia (Bivalvia, Unionidae), with the description of a new species. ZooKeys 1224: 187-209, DOI: 10.3897/zookeys.1224.140549
5FDEEB171FA05F25A9FA0D099E66D316.taxon	diagnosis	Diagnosis. Shell medium to large, rectangular or subrhomboidal, rather compressed to inflated. Anteriorly constricted, dorsal margin straight or slightly curved, slightly elevated posteriorly. One or two folds on posterior slope. Shell surface with fine or irregular growth lines, roughened on posterior slope or border of shell. One pseudocardinal tooth on each valve; lateral teeth obsolete.	en	Jeratthitikul, Ekgachai, Sutcharit, Chirasak, Prasankok, Pongpun (2025): An integrative approach to a revision of the freshwater mussel genus Songkhlanaia (Bivalvia, Unionidae), with the description of a new species. ZooKeys 1224: 187-209, DOI: 10.3897/zookeys.1224.140549
5FDEEB171FA05F25A9FA0D099E66D316.taxon	distribution	Distribution. Endemic to Indochina, including Songkhla Lake Basin, Tonle Sap Basin, and Middle to Lower Mekong basins.	en	Jeratthitikul, Ekgachai, Sutcharit, Chirasak, Prasankok, Pongpun (2025): An integrative approach to a revision of the freshwater mussel genus Songkhlanaia (Bivalvia, Unionidae), with the description of a new species. ZooKeys 1224: 187-209, DOI: 10.3897/zookeys.1224.140549
9BDBEDA98C975EA793681649DEF9E8B2.taxon	description	Figs 2 C – F, 5 B, Table 1	en	Jeratthitikul, Ekgachai, Sutcharit, Chirasak, Prasankok, Pongpun (2025): An integrative approach to a revision of the freshwater mussel genus Songkhlanaia (Bivalvia, Unionidae), with the description of a new species. ZooKeys 1224: 187-209, DOI: 10.3897/zookeys.1224.140549
9BDBEDA98C975EA793681649DEF9E8B2.taxon	diagnosis	Diagnosis. Shell large, subrhomboidal to ovate, moderately thickened, rather inflated. Anteriorly constricted, dorsal slightly curved, slightly elevated posteriorly. Posterior slope with one or two faint folds. Umbo rounded, moderately elevated. Shell surface with irregular growth lines, roughened on posterior slope and border of shell. Right valve with one smooth tubercular pseudocardinal tooth, left valve with hill-like or triangulate pseudocardinal tooth, subcompressed. V-shaped furrow on posterior end of hinge structure prominent, wide. Anterior adductor muscle scar impressed, ovate, separated from anterior protractor muscle scar. Umbo cavity moderately deep.	en	Jeratthitikul, Ekgachai, Sutcharit, Chirasak, Prasankok, Pongpun (2025): An integrative approach to a revision of the freshwater mussel genus Songkhlanaia (Bivalvia, Unionidae), with the description of a new species. ZooKeys 1224: 187-209, DOI: 10.3897/zookeys.1224.140549
9BDBEDA98C975EA793681649DEF9E8B2.taxon	distribution	Distribution. Tonle Sap Basin in Thailand and Cambodia (Crosse and Fischer 1876; Deshayes and Jullien 1876; this study), and the Lower Mekong Basin in Cambodia (Morlet 1884) (Fig. 3).	en	Jeratthitikul, Ekgachai, Sutcharit, Chirasak, Prasankok, Pongpun (2025): An integrative approach to a revision of the freshwater mussel genus Songkhlanaia (Bivalvia, Unionidae), with the description of a new species. ZooKeys 1224: 187-209, DOI: 10.3897/zookeys.1224.140549
F504AFD90E3258EFA2C7C5A745CCB2C8.taxon	description	Figs 4, 5 C Tables 1, 4	en	Jeratthitikul, Ekgachai, Sutcharit, Chirasak, Prasankok, Pongpun (2025): An integrative approach to a revision of the freshwater mussel genus Songkhlanaia (Bivalvia, Unionidae), with the description of a new species. ZooKeys 1224: 187-209, DOI: 10.3897/zookeys.1224.140549
F504AFD90E3258EFA2C7C5A745CCB2C8.taxon	diagnosis	Diagnosis. Shell large, subrhomboidal to ovate, thick, rather inflated. Anteriorly constricted, dorsal slightly curved, slightly elevated posteriorly. Posterior slope with one or two faint folds. Umbo rounded, wide, moderately elevated. Shell surface with irregular growth lines, roughened on posterior slope and border of shell. Right valve with one smooth triangular or high tubercular pseudocardinal tooth, left valve with well-developed, rectangular, rather broad and high pseudocardinal tooth. V-shaped furrow on posterior end of hinge structure prominent and wide. Anterior adductor muscle scar impressed, somewhat droplet-like, separated from anterior protractor muscle scar. Umbo cavity moderately deep and wide.	en	Jeratthitikul, Ekgachai, Sutcharit, Chirasak, Prasankok, Pongpun (2025): An integrative approach to a revision of the freshwater mussel genus Songkhlanaia (Bivalvia, Unionidae), with the description of a new species. ZooKeys 1224: 187-209, DOI: 10.3897/zookeys.1224.140549
F504AFD90E3258EFA2C7C5A745CCB2C8.taxon	description	Description. Shell large-sized (shell length 104.7 – 120.5 mm, shell height 73.8 – 78.5 mm, shell width 46.2 – 55.3 mm; Table 4), thick, rather high (H / L ratio = 0.65 – 0.70), inequilateral, subrhomboidal to ovate shape, rather inflated. Anterior margin rounded; posterior margin oblique above, subtruncate below; ventral margin slightly curved to straight. Dorsal margin curved to slightly curved; anterior low, rather constricted, slightly elevated to posterior end; posterior end high, resembling posterior wing in young specimens (Fig. 4 C). Umbo rounded, wide, moderately elevated, usually eroded. Posterior ridge wide and obtuse, not prominent; posterior slope with one or two faint folds running as curved line from umbo to posterior margin; lower one more prominent, ending at approximately middle of posterior margin, forming angulate point. Periostracum moderately thick, dark brown to black, eroded part white to coppery-brown. Shell surface with irregular growth lines, roughened on posterior slope and border of shell. Inner side of shell: ligament long, narrow, dark brown in color. Pseudocadinal teeth one on each valve; smooth, triangular or high tubercular shape on right valve; well-developed, smooth, rectangular shape, rather broad and high on left valve; in shell coupling position, pseudocadinal tooth on right valve situated well anteriorly. Lateral teeth obsolete. Posterior end of hinge structure with wide V-shaped furrow. Anterior muscle scars impressed; anterior adductor muscle scar somewhat droplet-like, contiguous with anterior pedal retractor, but separated from anterior protractor muscle scars; pedal retractor muscle scar rounded, protractor muscle scar bean-shaped. Posterior adductor muscle scar large, drop-like to ovate, shallow. Pallial line well-marked and continuous. Umbo cavity deep, wide, with one row of 5 – 10 muscle scars. Nacre whitish blue to yellowish. Siphon apertures with strip of dark pigmentation running along aperture edge. Exhalant aperture smooth, shorter than inhalant. Inhalant aperture with one row of conical papillae, varying in length, with more of the longer papillae near ventral edge. Small epithelial fold divides exhalant and inhalant aperture. Gills elongated and slightly ribbed; outer gills narrower than inner gills; anterior margin of inner gills slightly longer than outer gills. Labial palps elongate, somewhat pointed at tip. Glochidia unknown.	en	Jeratthitikul, Ekgachai, Sutcharit, Chirasak, Prasankok, Pongpun (2025): An integrative approach to a revision of the freshwater mussel genus Songkhlanaia (Bivalvia, Unionidae), with the description of a new species. ZooKeys 1224: 187-209, DOI: 10.3897/zookeys.1224.140549
F504AFD90E3258EFA2C7C5A745CCB2C8.taxon	etymology	Etymology. The species name songkhramensis refers to the Songkhram Basin, a sub-river basin of the Middle Mekong Basin in northeastern Thailand, in which this species is highly abundant. The type locality of the species is also situated in the Songkhram Basin.	en	Jeratthitikul, Ekgachai, Sutcharit, Chirasak, Prasankok, Pongpun (2025): An integrative approach to a revision of the freshwater mussel genus Songkhlanaia (Bivalvia, Unionidae), with the description of a new species. ZooKeys 1224: 187-209, DOI: 10.3897/zookeys.1224.140549
F504AFD90E3258EFA2C7C5A745CCB2C8.taxon	distribution	Distribution. The new species occurs in the Songkhram Basin and tributaries of the Mekong River in northeastern Thailand. It is a common freshwater mussel in the middle to upper part of Songkhram Basin (Fig. 3) and is usually found in high abundance.	en	Jeratthitikul, Ekgachai, Sutcharit, Chirasak, Prasankok, Pongpun (2025): An integrative approach to a revision of the freshwater mussel genus Songkhlanaia (Bivalvia, Unionidae), with the description of a new species. ZooKeys 1224: 187-209, DOI: 10.3897/zookeys.1224.140549
CFCEEF67CC9F5CE4A8B9B106AAACC3E3.taxon	description	Figs 2 A, B, 5 A, Table 1	en	Jeratthitikul, Ekgachai, Sutcharit, Chirasak, Prasankok, Pongpun (2025): An integrative approach to a revision of the freshwater mussel genus Songkhlanaia (Bivalvia, Unionidae), with the description of a new species. ZooKeys 1224: 187-209, DOI: 10.3897/zookeys.1224.140549
CFCEEF67CC9F5CE4A8B9B106AAACC3E3.taxon	diagnosis	Diagnosis. Shell medium, rectangular, thin, rather compressed. Anteriorly constricted, dorsal margin straight, slightly elevated posteriorly. Posterior slope with two prominent folds. Umbo tiny, slightly elevated. Shell surface with fine irregular growth lines, roughened on posterior slope. Right valve with one smooth tubercular or triangular pseudocardinal tooth, left valve with somewhat lingula-shaped tooth. V-shaped furrow on posterior end of hinge structure weak, not prominent. Anterior adductor muscle scar shallow, somewhat drop-like, contiguous with anterior protractor muscle scar. Umbo cavity shallow.	en	Jeratthitikul, Ekgachai, Sutcharit, Chirasak, Prasankok, Pongpun (2025): An integrative approach to a revision of the freshwater mussel genus Songkhlanaia (Bivalvia, Unionidae), with the description of a new species. ZooKeys 1224: 187-209, DOI: 10.3897/zookeys.1224.140549
CFCEEF67CC9F5CE4A8B9B106AAACC3E3.taxon	distribution	Distribution. So far, known only from the type locality in Songkhla Lake Basin, southern Thailand (Fig. 3).	en	Jeratthitikul, Ekgachai, Sutcharit, Chirasak, Prasankok, Pongpun (2025): An integrative approach to a revision of the freshwater mussel genus Songkhlanaia (Bivalvia, Unionidae), with the description of a new species. ZooKeys 1224: 187-209, DOI: 10.3897/zookeys.1224.140549
