Distribution of the newly invasive New Guinea flatworm Platydemus manokwari (Platyhelminthes: Geoplanidae) in Thailand and its potential role as a paratenic host carrying Angiostrongylus malaysiensis larvae.

Invasive species constitute one of the most serious threats to biodiversity and ecosystems, and they potentially cause economic problems and impact human health. The globally invasive New Guinea flatworm, Platydemus manokwari (Platyhelminthes: Geoplanidae), has been identified as a threat to terrestrial biodiversity, particularly soil-dwelling native species (e.g. molluscs, annelids and other land planarians), and is listed among 100 of the world's worst invasive alien species. We report here, for the first time, P. manokwari occurrences in many locations throughout Thailand, using voluntary digital public participation from the social network portals associated with the Thailand Biodiversity Conservation Group and collections of living flatworm specimens. Mitochondrial cytochrome c oxidase subunit I (COI) sequences confirmed that all collected flatworms were P. manokwari and placed them in the "world haplotype" clade alongside other previously reported specimens from France, Florida (USA), Puerto Rico, Singapore, French Polynesia, New Caledonia, and the Solomon Islands. In addition, infective stage larvae (L3) of the nematode Angiostrongylus malaysiensis were found in the flatworm specimens, with a 12.4% infection rate (15/121 specimens examined). Platydemus manokwari occurrence in Thailand and its capacity to carry L3 of Angiostrongylus should be of concern to biodiversity conservation and human health practitioners, because this invasive flatworm species may be involved in the life cycle of angiostrongylid worms in Thailand.

Genetic differences in the rat lungworm, Angiostrongylus cantonensis (Nematoda: Angiostrongylidae), in Thailand.

This study surveyed the genetic differences among Angiostrongylus cantonensis (A. cantonensis) using the mitochondrial cytochrome b (cytb) gene. Partial cytb sequences were determined for 91 worms from eight locations in Thailand. Using morphological techniques, the nematodes were found to be A. cantonensis. Phylogenetic analysis found two main clades, which were subdivided into four subclades (clusters). Haplotype network analysis showed that 11 distinct cytb haplotypes were also present in four groups of A. cantonensis. There was no observable relationship between the genetic differentiation of gene flow and geographical distance. This low genetic variation and geographical distribution of A. cantonensis in each location indicates a founder effect, which may have resulted from multiple independent origins, and suggests that haplotypes migrated from endemic areas via human-related activities.