Ensidens ingallsianus (Lea, 1852)

Ng, Ting Hui, Jeratthitikul, Ekgachai, Sutcharit, Chirasak, Chhuoy, Samol, Pin, Kakada, Pholyotha, Arthit, Siriwut, Warut, Srisonchai, Ruttapon, Hogan, Zeb S. & Ngor, Peng Bun, 2020, Annotated checklist of freshwater molluscs from the largest freshwater lake in Southeast Asia, ZooKeys 958, pp. 107-141 : 107

Ensidens ingallsianus (Lea, 1852) Fig. 3D

Unio ingallsianus Lea, 1852: 282, pl. 24, fig. 41. Type locality: “Siam”.

Ensidens ingallsianus ingallsianus : Brandt 1974: 288, pl. 24, fig. 47.

Ensidens ingallsianus : Muanta et al. 2019: 224-231.

Material examined.

CIFI.MOL.019, CIFI.MOL.020, CIFI.MOL.021, CIFI.MOL.022, MUMNH.UNI.2617, MUMNH.UNI.2626, MUMNH.UNI.2634, MUMNH.UNI.2642, MUMNH.UNI.2644, MUMNH.UNI.2649, MUMNH.UNI.2655, MUMNH.UNI.2657, MUMNH.UNI.2666, MUMNH.UNI.2668, MUMNH.UNI.2672, MUMNH.UNI.2673, ZRC.MOL.015640, ZRC.MOL.015641, ZRC.MOL.015642, ZRC.MOL.015643.

Distribution and habitat.

Tonle Sap Lake at Kampong Chhnang, Siem Reap and Kampong Thom Provinces, Sen River in Kampong Thom Province, Sangkae River in Battambang Province, Chi Kraeng River and Kralanh River in Siem Reap Province, Tonle Sap River in Kandal Province (locality no. 3, 7, 8, 12, 13, 21, 23, 24, 30, 36, 40 and 44); in soft muddy substrate.

Remarks.

Not sold for food, collected as by-catch of Corbicula and Mekongia harvests, and were often observed to be discarded along with other large unionids. The species previously identified as Ensidens ingallsianus has recently been revealed as a complex of two species ( Muanta et al. 2019), one clade that is restricted to the Chao Praya River basin in Thailand, and another clade from the Tonle Sap and Bang Prakong River basins ( Muanta et al. 2019). These two clades could be separated by using the position of the umbo, which is more anterior than in the Tonle Sap clade. As far as we know, there is no other available name for the species from the Tonle Sap basin. Therefore, the name Ensidens ingallsianus is herein used until the systematic revision of this species complex is completed.

Figures

Figure 3. Freshwater bivalves of the Tonle Sap basin, Cambodia (Pharidae and Unionidae) A Novaculina siamensis B Bineurus mouhotii C Contradens contradens D Ensidens ingallsianus E Hyriopsis bialata F Hyriopsis delaportei G Monodontina cambodjensis H Physunio micropterus I Pilsbryoconcha linguaeformis J Pilsbryoconcha lemeslei and K Scabies mandarinus. Scale bars: 10 mm, unless stated otherwise. Photographs by K Macharoenboon.