Allodiaptomus nongensis, a new diaptomid copepod (Copepoda: Calanoida) from a tributary of the Mekong River, with notes on its consumption by local people in Central Laos

Abstract

A new calanoid copepod, Allodiaptomus nongensis n. sp., is herein described based on samples collected from the Xe Lanong River (a tributary of the Mekong River), and 13 other localities in Central Laos. This is the sixth species of the genus Allodiaptomus Kiefer, 1936. The other five members in the genus were recorded from India, South China, Cambodia, Thailand, and Vietnam. The features that stand out in the new species are in the male: the right caudal ramus has a large, biacuminate, conical process proximally, and the Exp-2 of the right P5 has a hook-shaped principal spine proximally. The new species is abundant in both temporary and permanent waters, but is restricted to Savannakhet Province. This Laotian endemic copepod is referred to by local people as “Pa Khayong”, which means tiny fish. Since high densities of this copepod can be found in the dry season (December until May), several man-made copepod traps are placed by local people along the river banks in Muang Nong District. Interestingly, large concentrations of individuals (body length: ~1 mm) belonging to the new species are harvested and consumed by these villagers. Additional information about this species and the copepod fisheries by local people in this area is provided herein. In this paper, the reassignment of Allodiaptomus rarus to the genus Mongolodiaptomus is proposed.