Abstract
Alien crayfish, Cherax quadricarinatus (von Martens, 1868) is one of the potential cultivated freshwater species in Malaysian waters; however, its establishment in freshwater ecosystems may alter the native taxa due to the high environmental tolerance and capability of transmitting parasites. We report here the first evidence of the ectosymbiont Craspedella pedum (Cannon and Sewell, 1995) described by morphological observations and species identification using molecular techniques, originating from C. quadricarinatus collected in Malaysian freshwater. A 940-base pair long 18S ribosomal rDNA fragment, in particular, was successfully sequenced and aligned. The Neighbour-Joining and Maximum Likelihood analyses revealed a high degree of similarity with a low genetic distance between C. pedum from this study and C. pedum from Thailand. This finding represents the second discovery of temnocephalid symbionts in Malaysian waters, but first made using molecular data. This clarification may help to improve understanding of the temnocephalid infestation in Malaysia, as well as potential threats to native species and changes in ecosystem diversity where the host was introduced.
