Rungthip Plongsesthee’s research while affiliated with Burapha University and other places

Environmental associations favorable for benthic loaches within the families Nemacheilidae and Balitoridae were the objective of this study that was conducted at 160 sites within five river systems: Southeastern, Mekong, Chao Phraya, Maeklong and Peninsula, in the central region of Thailand. Loaches in this study represented seven genera and 19 species; one each of Tuberoschistura and Homalopteroides, two Acanthocobitis, Homaloptera and Pseudohomaloptera, four Nemacheilus and seven Schistura. Fewest species (n = 3) were found in the Southeastern system with four species from each of the Mekong, Chao Phraya and Peninsula systems and 13 species in the Maeklong system. Species diversity within all systems was greatest for Schistura. Species and relative abundance of all fishes and of loaches varied directly and inversely, respectively, with river order for the two rivers in which this was examined. Abundances varied widely among species and sites with the most abundant species being Schistura aurantiaca, Schistura cf. sexcauda, Homalopteroides smithi and Acanthocobitis zonalternans. Species' distributions across all five river systems examined by canonical correlation analysis (CCA) varied significantly with six environmental variables. Of greatest significance were elevation and water temparature followed by water velocity, ambient oxygen, pH and Silica. Several adaptations for co-existence in fast flowing water are identified and discussed.

Schistura crocotula, a new species, is described from Khanan River, Prachuap Khiri Khan Province, southern Thailand. It is distinguished from other species of Schistura in Southeast Asia by a depressed head; 6-11 dark brown bars against an orange background; the first bar is the widest, two bars are under dorsal fin; interspaces are often indistinct on posterior part of body; a thick black bar at the base of the caudal fin.

Recent fieldwork has revealed the presence of six species of Schistura McClelland 1838 in the Mae Khlong basin in south-western Thailand. These include S. sexcauda (Fowler 1937), S. balteata (Rendahl 1948), S. mahnerti Kottelat 1990, the recently described S. aurantiaca Plongsesthee et al. 2011 and S. tenebrosa Kangrang et al. 2012, and a newly discovered species described herein. Schistura sexcauda previously was the only Schistura species known in the Mae Khlong, and it was mis-identified as S. desmotes (Fowler 1934). Schistura pantherina, n. sp., is easily distinguished from all other species of Schistura by its distinctive color pattern. It appears to be endemic to the Mae Nam Kwai Noi system.

Sexually dimorphic characteristics are described for four species of Schistura from the Mae Khlong basin and peninsular Thailand. Males of S. mahnerti have a suborbital flap and rows of unculi on the upper surfaces of the pectoral-fin rays. Females of S. mahnerti have a suborbital groove. None of the morphological measurements differ significantly between males and females of S. mahnerti. In the other three species, S. aurantiaca, S. cf. aurantiaca, and S. sexcauda, all indi-viduals lack the flap or groove, but most males have a conspicuous black botch on the procurrent rays of the upper lobe of the caudal fin, a feature absent in most females. Some morphometric characteristics vary between sexes of these spe-cies. Sexually dimorphic traits presumably have a function related to reproduction; however, little is known about repro-duction in Schistura, and variation in morphology in relation to habitat or other environmental factors has not been studied.

Diversity of freshwater fishes is spatially heterogeneous but, for the most part, the reasons remain poorly understood in Thailand. This review attempts to promulgate factors linking freshwater fishes and habitats, particularly morphological, physiological and ecological, drawing on principles and information from elsewhere but with the focus being Thailand. The review identifies areas in need of improved understanding with an assurance in the future of generous dividends for the investment.

Schistura aurantiaca, new species, is described from the Mae Khlong basin in western Thailand. It is distinguished from all other species of Schistura by a unique color pattern of 3-9 orange bars on the side of the body, with the 1st bar immediately behind the head and the 2nd bar near the dorsal-fin origin and widely separated so that most of the nape and the anterior side of the body are uniformly brown. The species reaches only 41 mm SL and in-habits shallow gravel and rubble riffles in small streams.

Total length-weight regressions on logarithmic transformed data are provided for 33 species, with 26 apparently being first estimates. All regressions are highly significant with slope values between 2.5720 and 3.4436. Slopes and intercepts of length-weight regressions did not differ significantly with location for each of three species. Preservation in 10% formalin for 10 days followed by 30 days in 70% ethanol did not significantly influence regression slopes for the three species, length ranges and/or locations examined (ancova). Significance among regression intercepts was equivocal with ancova analyses mostly suggestive of differences and overlap of 95% confidence limits mostly suggestive of similarities.