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Anentome helena is a widespread freshwater snail, especially in Thailand. It is a successful predator in the ecosystem and an intermediate host of trematodes. The radula is a specific character of gastropods for feeding and often uses to limited species. However, it’s neither all morphological features of radulae and radular teeth are functionally adaptive or optimized for a specific function, nor all morphology should be viewed in an evolutionary context. This study aims to compare the radular morphology of assassin snail A. helena from different microhabitats in Northern Thailand and performs DNA fingerprints analysis using the high annealing temperature-random amplified polymorphic DNA marker (HAT-RAPD) of A. helena and related species. A total of 140 adult individuals of A. helena were collected from 14 different localities throughout Northern Thailand. There were 4 different types of microhabitats of A. helena including sand, mud, cement and plant root. The results showed that there were two morphotypes in the A. helena complex. The radula was investigated by using a light microscope and scanning electron microscope (SEM). The radula of all A. helena was stenoglossan but different in number and size of cusps on a central tooth and lateral teeth. Moreover, the radular teeth of A. helena from sand differed from those other microhabitats with more blunt-cusps teeth. HAT-RAPD analysis with 8 primers could be identified species-specific banding patterns for each freshwater snail species. In addition, it was separated two morphotypes of A. helena into two groups and showed the result that it was not related to their microhabitats. This finding has demonstrated morphological adaptation of A. helena radula in number and size of cusps which seems to be related to preferred substrata. This study will help to understand the ecology that can affect to the radular morphology of A. helena. In addition, HAT-RAPD profiling was a useful tool to determine the genetic relationship between freshwater snail species and variation that might occur on their radular morphology.
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