Fish diversity of a spring field in Hopong Town, Taunggyi District, Shan State, Myanmar (the Salween River Basin), with genetic comparisons to some “species endemic to Inle Lake”

Abstract

Hopong, a small town in the Salween (Thanlwin) River Basin, Myanmar, is located 35 km northeast of Inle Lake, a famous ancient lake with numerous endemic fish species. We surveyed the fish fauna of a spring pond in Hopong in 2016, 2019 and 2020 and identified 25 species. Of these, seven, including Inlecypris auropurpureus and Sawbwa resplendens, had been considered endemic to Inle Lake and at least three species were genetically unique. Eight were suspected or definite introduced species, including Oreochromis niloticus and Gambusia affinis. We were unable to identify a nemacheilid species of the genus Petruichthys, which would need a taxonomic examination. The Hopong area is being developed rapidly and, hence, it is crucial to conserve its native fish species and the freshwater ecosystems.

Cryptic genetic divergence of the red dwarf rasbora,Microrasbora rubescens, in and around Inle Lake: implications for the origin of endemicity in the ancient lake in Myanmar

“…A total of 95 specimens of M. rubescens (68 for genetics and 83 for morphometrics) were collected from eight sites in the Inle region covering its distribution range from 2014 to 2016 (Table 1; Kano et al ., 2016, 2022): Nyaungshwe, north of Inle Lake; Ye Byong Gyi (YBG) and Min Ywar Village (Min), south of Inle Lake; Mobye Dam Lake, downstream of Inle Lake; Loikaw, downstream of Mobye Dam; Heho, 20 km northwest of Inle Lake; Aungpan, 10 km further west of Heho; and Hopong, 30 km northeast of Inle Lake (Figure 1; Table 1 and Supporting Information Table S1). Of these, Nyaungshwe, YBG, Min, Mobye Dam Lake and Loikaw were collectively referred to as Inle.…”

“…Hopong and Inle Lake are close in terms of linear distance but are separated by highlands. A small river in Hopong joins the downstream river of Inle Lake at a point approximately 20 km east of Loikaw, and Hopong and Inle Lake are about 400 km apart through the rivers (Kano et al ., 2022). In the analysis, the specimens from YBG and Min were pooled because they were close to each other in the same water system (Figure 1).…”

“…(2022) investigated the ichthyofauna of Hopong, which is located approximately 30 km northeast of Inle Lake in a basin of the other branch of the Salween River, and reported that seven fish species thought to be endemic to Inle Lake also inhabited Hopong ( i.e ., Channa harcourtbutleri (Annandale, 1918), Danio erythromicron (Annandale, 1918), Inlecypris auropurpureus (Annandale, 1918), Mastacembelus caudiocellatus (Boulenger 1893), Microrasbora rubescens Annandale, 1918, Petruichthys brevis (Boulenger 1893) and Sawbwa resplendens Annandale, 1918). Furthermore, genetic differentiation among regions has been suggested for some of these fishes ( e.g ., M. rubescens and I. auropurpureus ) (Kano et al ., 2022). In this study, the authors use the term “Inle region” to refer to Inle Lake and the surrounding inflow and outflow river areas, such as Heho and adjacent Hopong area (Figure 1).…”

“…The most closely related species of M. rubescens are not known; nonetheless, Devario acuticephala (Hora, 1921) and Devario horai (Barman, 1983) from northeastern India, and Devario sondhii (Hora & Mukerji, 1934), which occurs sympatrically with M. rubescens in some areas, are suspected to be related to M. rubescens because of their similarity in body colour (Bleher, 2018). Although M. rubescens was considered “endemic to Inle Lake,” it is now widely found in the Inle region, including Heho and Hopong (Annandale, 1918; Fuke et al ., 2021; Kano et al ., 2016; Kano et al ., 2022). Furthermore, mtDNA barcode information suggests the regional differentiation in M. rubescens with at least two (Collins et al ., 2012) or three (Kano et al ., 2022) distinct lineages, possibly reflecting topographical features in this region.…”

“…Although M. rubescens was considered “endemic to Inle Lake,” it is now widely found in the Inle region, including Heho and Hopong (Annandale, 1918; Fuke et al ., 2021; Kano et al ., 2016; Kano et al ., 2022). Furthermore, mtDNA barcode information suggests the regional differentiation in M. rubescens with at least two (Collins et al ., 2012) or three (Kano et al ., 2022) distinct lineages, possibly reflecting topographical features in this region. M. rubescens is found in slow or stagnant flowing environments (Annandale, 1918), yet data on its habitat, ecology or life history are limited.…”