Biodiversity assessment of freshwater fishes : Thailand as a case study

A key challenge in biodiversity is: How many species are there on earth? This issue is especially acute in poorly surveyed regions with high diversity, particularly Southeast Asia that also experiences many limitations such as lack of funds, documents and experts. To help meet this challenge, I have developed a five-tiered approach for diversity measurement of freshwater fish for use in Thailand. This is: (1) the creation of a newly updated species inventory that uses existing data; (2) exploration of the patterns of species richness, endemism, and uniqueness; (3) estimation of the total species richness; (4) investigation of patterns of rarity; and (5) integration of this knowledge into conservation practice. The system should be applicable to other regions and other taxa where a similar challenge exists. My work shows that eight hundred and seventy-two species in 17 orders, 55 families and 255 genera of freshwater fishes, accounting for roughly 10% of the world’s freshwater fish diversity, have been reported for Thailand to date. This number was derived from information in the museum collections, literature and all other available sources, including reports written in Thai as well as in English. During this work I uncovered many gaps in biodiversity information, in terms of taxonomic and spatial records, though some families and basins are better represented than others. Taxonomic uncertainty also continues to be a challenge for taxonomists and users. The high diversity of freshwater fishes in Thailand is the result of both high alpha (α) diversity (diversity within a particular locality) and beta (β) diversity (diversity differences between localities). I concluded that the substantial beta diversity I detected is associated with the geographical separation of the six river basins in Thailand. For example, the species composition of freshwater fishes in the Salween Basin dramatically differs from all other basins of Thailand. In contrast, the Chao Phraya Basin and the Mekong Basin contain the greatest number of shared species. Approximately 55% of species have a wide distribution range (being reported from more than two basins), whereas 45% are highly restricted within a single basin. Analyses using species richness estimators suggest that the figure of 872 species is an underestimate and that there may be between 1000 and 1300 fish species in Thailand, in other words an increase of between 14.7% and 49.1% over the list I compiled (which is itself an increase of 52.2% over the last report in 1997). Freshwater fish have become increasingly vulnerable to anthropogenic activities. Of the 872 Thai fish species, 6.8% and 15.1% are globally and nationally threatened, respectively. Nonetheless, a striking feature of the database is that the conservation status of the vast majority of species has not so far been assessed, either globally or nationally. Scientists and policy makers will find these results useful in appreciating the magnitude of the tasks involved in surveying, describing and conserving the country’s freshwater fish biota. My work highlights localities and taxa where conservation is a priority and is thus an important resource for policy makers and conservation planners concerned with the management of freshwater fish in Thailand

A new species of the ant Platythyrea clypeata species group (Hymenoptera, Formicidae, Ponerinae) from continental Asia

The Platythyrea clypeata species group is reviewed and three species, including one new species, P. homasawini sp. nov., are recognized. This species group is distinguished from the P. parallela species group by the reddish-brown body, the elliptical shape of the propodeal spiracle, the elongate antennal scape, and the distinctly narrowed posteriad space between frontal carinae. Platythyrea homasawini sp. nov., from Thailand and China, is described based on the worker caste. The type series of the new species was collected on the forest floor from dead wood in an advanced stage of decomposition. A key to the Oriental species of the genus Platythyrea based on the worker caste is provided

An updated checklist of the ants of Thailand (Hymenoptera, Formicidae)

Thailand has a great diversity of ant fauna as a zoogeographical crossroads and biodiversity hotspot. The last publication presenting a Thai ant checklist was published in 2005. In the present paper, based on an examination of museum specimens and published records, a comprehensive and critical species list of Thai ants is synthesized. Currently, 529 valid species and subspecies in 109 genera among ten subfamilies are known from Thailand with their diversity and distribution within 77 provinces presented and assigned to six geographical regions. Furthermore, Thailand is the type locality for 81 ant species. Forty-one species are here newly recorded for Thailand with photographs illustrating these species. The checklist provides information on distribution and a comprehensive bibliography. This study will also serve as a guide for the upper northeast and central Thailand, which are poorly sampled; a comprehensive reference list relating to endemic taxa and localities where conservation is an important priority, thus an essential resource for policy makers and conservation planners concerned with the management of insect diversity in Thailand; and a list of exotic ant species found in Thailand, which could possibly impact the ecological balance

The diversity of acorn barnacles (Cirripedia, Balanomorpha) across Thailand’s coasts: The Andaman Sea and the Gulf of Thailand

The acorn barnacle is a sessile crustacean, inhabiting the intertidal areas of tropical and temperate regions worldwide. According to current practices on Cirripedia morphology, shell, opercular valves, and arthropodal characters including cirri and mouthparts are used as a tool for taxonomic classification, and using these characteristics the present study aimed to provide better resolution for the barnacle diversity and geographical distribution within coastlines of Thailand: the Andaman Sea and the Gulf of Thailand. A total of ten species belonging to three families (Chthamalidae, Tetraclitidae, and Balanidae) were identified in this study. Subsequently, five species were newly recorded for the first time from Thailand’s coasts: Newmanella spinosus Chan & Cheang, 2016, Euraphia hembeli Conrad, 1837, Euraphia depressa (Poli, 1795), Tetraclita kuroshioensis Chan, Tsang & Chu, 2007, and Tetraclita singaporensis Chan, Tsang & Chu, 2007. The others, already mentioned in previous records, include: Tetraclita squamosa (Bruguière, 1789), Chthamalus malayensis Pilsbry, 1916, Amphibalanus amphitrite (Darwin, 1854), Amphibalanus reticulatus (Utinomi, 1967), and Megabalanus tintinnabulum (Linnaeus, 1758). Interestingly, acorn barnacles along the Andaman Sea occur abundantly, and are much higher in number of species (up to 8 species) than those found in the Gulf of Thailand’s coast (up to 6 species). This biased trend of species’ preferences is possibly due to the differences in oceanographic nature between two coastlines and the history of barnacle colonization

Discovery of Neonrosella vitiata (Darwin) and Newmanella spinosus Chan & Cheang (Balanomorpha, Tetraclitidae) from the Andaman Sea, eastern Indian Ocean

In this present study, distantly related acorn barnacle species in the subfamily Newmanellinae (Cirripedia, Thoracica, Tetraclitidae), including Neonrosella vitiata (Darwin, 1854) and Newmanella spinosus Chan & Cheang, 2016, were discovered in the Andaman Sea of Thailand. Neo. vitiata can be readily distinguished from other newmanellids by shell plate and operculum morphology (external shell, tergum geometry, and pattern of parietal tube) and arthropodal characters (presence of basi-dorsal point at base of penis and triangular spines on cirri, setal type, and mouth parts). Both species were found to share overlapping territories on rocks at the rockweed zone, an area submerged under seawater most of the time throughout the year. This study highlights the first discovery of Neonrosella in the eastern Indian Ocean, whose ultrastructure compared to Newmanella is redescribed and illustrated here based on scanning electron microscopy