Species Composition and Distribution of Freshwater Calanoida and Cyclopoida (Copepoda) of Northeast Thailand

A series of samples, collected from different types of freshwater habitats in northeastern Thailand during 1993-1997, contained 16 species of Calanoida and 15 of Cyclopoida. Of these, seven species (Eucyclops serrulatus, Ectocyclops phaleratus, Ectocyclops rubescens, Mesocyclops as-pericornis, Mesocyclops splendidus, Thermocyclops decipiens, and Thermocyclops taihokuensis) are new to the fauna of Thailand. Three species (Phyllodiaptomus praedictus, Phyllodiaptomus christineae, and Allodiaptomus rarus) appear to be endemic to Thailand. The most frequently encountered species of calanoids were Neodiaptomus botulifer, Neodiaptomus yangtsekiangensis, Allodiaptomus calcarus, and Phyllodiaptomus praedictus, while those for the Cyclopoida were Mesocyclops thermocyclopoides, Thermocyclops crassus, and Microcyclops varicans. The peculiarity of the Thai Calanoida is a high degree of co-occurrence of several species in the same habitats.