Novaculina siamensis Morlet, 1889

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

Novaculina siamensis Morlet, 1889 Fig. 3A

Novaculina siamensis Morlet, 1889: 198, pl. 9, fig. 4. Type locality: "Marais de Chantakam Siam".

Material examined.

MUMNH.PHA.001, MUMNH.PHA.002

Distribution and habitat.

Tonle Sap River in Kampong Chhnang Province (locality no. 41 and 43); tough clay bottom substrate, in which it makes cylindrical holes.

Remarks.

The discovery of Novaculina siamensis in Tonle Sap River is a new record for Cambodia and fills in the distribution gap of the genus in Indochina. This species was first described from "Chantakam, Siam" [Prachantakham District, Prachinburi Province, Thailand], but the type series is thought to be lost ( Bolotov et al. 2018). The type locality is probably a tributary of Bang Pakong River, in eastern Thailand. Brandt (1974) reported an additional population from Pasak River in Thailand. Sayenko et al. (2017) reported another abundant population from the Mekong Delta in Vietnam. The Tonle Sap River population is smaller, with more prominent umbo and lower posteriorly than the Thai population. All the collected shells were found empty, inside their cylindrical holes, under the shallow water near the riverbank. Only one living animal was obtained.

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.