Morphological and molecular diversity patterns of the genus Tropodiaptomus Kiefer, 1932 (Copepoda, Calanoida, Diaptomidae) in Thailand

Tropodiaptomus is one of the most specious genera in the family Diaptomidae, but it is often rare in terms of distribution and abundance. Moreover, Tropodiaptomus species show a noteworthy variability in some of the morphological characters considered of prime importance in diaptomid taxonomy, and the presence of cryptic or pseudocryptic species is likely. Thus, through a geographically-wide sampling in Thailand, we aimed to investigate the local diversity of the genus and to compare the morphological and molecular diversity pattern based on mitochondrial and nuclear genes sequences. DNA taxonomy was also implemented in order to check whether the Tropodiaptomus lineages were independent species according to the “evolutionary genetic species concept”. Six Tropodiaptomus morphospecies were found, three of which are putative species new to Science pending a formal description. The finding of such a high incidence of undescribed species stresses the existence of a significant “Linnean shortfall” affecting Thai diaptomids. The molecular results showed that most of the studied species could be identified consistently with their morphology-based taxonomy. However, Tropodiaptomus vicinus and T. cf. lanaonus showed a high level of genetic diversity, suggesting that traditional morphological techniques might be inadequate for correctly assessing their taxonomical status

Taxon richness and biogeography of the Cladocera (Crustacea: Ctenopoda, Anomopoda) of Thailand

At present, 99 species of cladocerans are known from Thailand, but up to ten more have not been identified to species, particularly in Chydorus, Ephemeroporus and Pleuroxus. Cosmopolitan species are a minority, while wide-ranging circumtropical taxa are an important element, beside species that only occur in the tropics-subtropics of two continents. At least three species are suspected of a neotropical - southeast Asian disjunction, while three more are provisionally considered endemic of Thailand. Daphnia, as usual in the tropics, is rare and reduced to the single D. lumholtzi