Friday, February 17, 2012

[Ichthyology • 2006] Tonlesapia tsukawakii | Tonle Sap dragonet • a new genus and species of freshwater dragonet (Perciformes: Callionymidae) from Lake Tonle Sap, Cambodia

Tonlesapia tsukawakii, new genus and species, is described from the northwestern part of Lake Tonle Sap, Cambodia. Tonlesapia tsukawakii is distinguished from all known genera and species of Callionymidae by the following combination of characters: first dorsal fi n absent; 8 dorsal-fi n rays; 7 anal-fi n rays; all dorsal- and anal-fin rays, except last ray, divided into 2 at base, unbranched; opercular membrane fused with body, not forming a free skin fl ap. Tonlesapia tsukawakii is the only species in the family which lives in freshwater throughout its entire life cycle.

Tonlesapia, new genus
Type species. Tonlesapia tsukawakii, new species.

Etymology. Tonlesapia is named for Lake Tonle Sap (Tonlé Sap) in Cambodia. Gender feminine.

Distribution. Currently known only from the northwestern part of Lake Tonle Sap, Cambodia. 

Ecological notes. The type specimens of T. tsukawakii were collected by small nets by a local fisherman in Siem Reap with the following species of fishes (all registered at AMS collection): Coilia lindmani (Engraulidae), Clupeoides borneensis (Clupeidae),  Albulichthys albuloides,  Cyclocheilichthys armatus, Labiobarbus leptocheila, Thryssocypris tonlesapensis (Cyprinidae),  Parambassis siamensis, Parambassis wolffii (Ambassidae), Polynemus aquilonaris (Polynemidae), Boesemania microlepis (Sciaenidae),  Glossogobius aureus (Gobiidae), and Hyporhamphus limbatus (Hemiramphidae). Of these, the dominant species were Coilia lindmani and Polynemus aquilonaris, accounting for close to 90 % of the whole catch. These two species occur offshore and have never been observed inshore, nor in channels or ponds scattered around the lake. This suggests that T. tsukawakii was likely collected offshore too. The substrate of the lake is mud.

Etymology. Named for Dr. Shinji Tsukawaki of Kanazawa University, in acknowledgment of his kind and invaluable assistance during our ichthyological surveys in Cambodia

Motomura, H.; Mukai, T. 2006: Tonlesapia tsukawakii, a new genus and species of freshwater dragonet (Perciformes: Callionymidae) from Lake Tonle Sap, Cambodia. Ichthyological exploration of freshwaters, 17(1): 43-52.: