Plectostoma klongsangensis (Panha, 1997)

From a conchological point of view, this species appears not to be related to Plectostomaspecies from the Malay Peninsula and Sumatra. Instead, it is almost identical to Plectostomamirabile, an endemic species from Gomantong Cave, Sabah, Borneo. These two species are separated by the South China Sea and located more than 2000 km apart. It remains to be determined whether this similarity is due to a disjunct distribution of closely related forms, or rather convergent shell evolution.

The taxonomic status of the species remains doubtful. In the original publication, Panha (1996)compared it with Plectostoma heteropleuron (Vermeulen 1994) and Plectostoma perspectivum(Vermeulen, 1994) from Northern Borneo, but not with Plectostoma mirabile (Smith, 1893), which has an almost identical shell as Plectostoma klongsangensis. This is all the more remarkable, asPlectostoma mirabile (Smith, 1893) was treated in Vermeulen (1994), where both Plectostomaheteropleuron and Plectostoma perspectivum were originally described.

In conclusion, more data are needed to verify the taxonomic status and the interesting biogeography of this species.