Abstract
Within the subfamily Danioninae, rasborine cyprinids are known as a ‘catch-all’ group, diagnosed by only a few characteristics. Most species closely resemble each other in morphology. Species identification is therefore often challenging. In this study, we attempted to determine the number of rasborine species occurring in samples from the Mesangat wetlands in East Kalimantan, Indonesia, by using different approaches. Morphological identification resulted in the distinction of five species (Trigonopoma sp., Rasbora cf. hubbsi Brittan, 1954, R. rutteni Weber and de Beaufort, 1916, R. trilineata Steindachner, 1870, and R. vaillantii, Popta 1905). However, genetic species delimitation methods (Poisson tree processes (PTP) and multi-rate PTP (mPTP)) based on DNA barcodes and principal component analysis (PCA) based on homologous geometric morphometric landmarks, revealed a single cluster for Trigonopoma sp. and R. trilineata, respectively, whereas the remaining traditionally identified species were distinguished neither by DNA barcodes nor by the morphometry approach. A k-mean clustering based on the homologous landmarks divided the sample into 13 clusters and was thus found to be inappropriate for landmark data from species extremely resembling each other in morphology. Due to inconsistent results between the applied methods we refer to the traditional identifications and distinguish five rasborine species for the Mesangat wetlands.
Highlights
Sundaland (Southeastern Asia) is one of the global biodiversity hotspots [1]
Specimens identified as Rasbora trilineata and Trigonopoma sp. form a respectively distinct clade, and both show significant evolutionary distances to the rasborine species included in our analysis and available from GenBank: R. trilineata differs by a nearest neighbour distance (NND) of 4.2% K2P from the Rasbora trilineata specimen with GenBank accession EF452883 used in the study of Mayden et al [63] (Figure 2) and Trigonopoma sp. from the Mesangat area differs by a NND of 15.9% K2P from Trigonopoma gracilis (Figure 2)
The differentiation of R. cf. hubbsi from the nominal species is based on caudal fin colora
Summary
Sundaland (Southeastern Asia) is one of the global biodiversity hotspots [1]. About 400 freshwater fish species are endemic to the region [2], and species determination remains a major challenge especially in species-rich groups of freshwater fishes [3]. The Cyprinidae, with 57 species is the most species-rich family, dominated by the genera Osteochilus (10 spp.) and 11 Rasbora species (R. atranus Kottelat and Tan, 2011, R. bankanensis (Bleeker, 1853), R. cephalotaenia (Bleeker, 1852), R. elegans Volz, 1903, R. lacrimula Hadiaty and Kottelat, 2009a, R. laticlavia Siebert and Richardson, 1997, R. subtilis Roberts, 1989, R. trilineata Steindachner, 1870, R. trifasciata Popta, 1905, R. vaillantii Popta, 1905, and R. volzii Popta, 1905) [12,20,21,22,23,24,25] Both Christensen [20] and Kottelat [12] stated that their species lists are far from being complete, and that further studies are necessary. The clustering approach was applied to aid in solving discrepancies between morphological and genetic identification, and to estimate the number of rasborine species entities of the Mesangat wetlands
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