Taxonomic revision and conservation assessment of the Southeast Asian freshwater mussel genusChamberlainiaSimpson, 1900

Abstract

Chamberlainia hainesiana (Lea, 1856) (Unionidae) is the most economically important freshwater mussel in Thailand and is commonly used in food, spiritual ceremonies and pearl culture. Despite the clear economic importance of this monotypic genus, the distribution and diversity of Chamberlainia Simpson, 1900 are poorly understood. We set out to re-evaluate the taxonomic and geographic boundaries of Chamberlainia using molecular and morphological data gathered from recently and historically collected material. Our cytochrome c oxidase subunit I gene tree recovered three divergent species-level lineages in the genus Chamberlainia. Fourier shape analysis of 60 digitized Chamberlainia shell outlines revealed evidence of two morphologically divergent groups that could be statistically distinguished 88% of the time. We used this evidence to recognize two genetically and morphologically divergent Chamberlainia species, C. hainesiana and C. duclerci (Rochebrune, 1882) stat. res. Geographical information from 46 museum records was used to map the distribution of Chamberlainia. These results are discussed in the context of their taxonomic, biogeographic and conservation implications.

Integrative Taxonomic Reappraisal and Evolutionary Biogeography of the Most Diverse Freshwater Mussel Clade from Southeast Asia (Pseudodontini)

“…In particular, certain hosts of all species are unknown, although an unspecified cyprinid fish was mentioned as a host of Pilsbryoconcha exilis glochidia [56]. Moreover, suitable hosts were determined for only a few freshwater mussel species from other tropical Asian tribes, that is, Hyriopsis myersiana (Lea, 1856) (Rectidentini) [103], Chamberlainia duclerci (Rochebrune, 1882) (Chamberlainiini) [104,105], Lens contradens (Lea, 1838), Physunio superbus (Lea, 1843) (Contradentini) [56], Lamellidens ferrugineus (Annandale, 1918), and L. marginalis (Lamarck, 1819) (Lamellidentini) [106]. Panha [56] listed 14 fish species and one unspecified palaemonid shrimp (Decapoda: Palaemonidae) as larval hosts of freshwater mussels from the Chao Phraya Basin in Thailand but, in most cases, it was impossible to perform a taxonomic identification of the observed glochidia.…”

A freshwater mussel species reflects a Miocene stream capture between the Mekong Basin and East Asian rivers

“…Cristaria clessini is endemic to the western parts of Honshu Island, Japan (Lopes-Lima et al 2020); C. beirensis inhabits the Amur Basin, as well as streams draining to the Sea of Japan and the Yellow Sea; the range of C. radiata crosses China (Graf and Cummings 2021); and C. truncata is distributed in Northern Vietnam (Do et al 2018). Cristaria plicata is considered to be the most widespread and abundant taxon within the genus, the range of which extends throughout the Amur (Russia, northeastern China, and Mongolia) and Yangtze (eastern China) basins, water bodies of central Sakhalin, Japan, South Korea, and northern Vietnam (Prozorova et al 2004;Klishko et al 2014Klishko et al , 2016Do et al 2018;Wu et al 2018;Bolotov et al 2020;Lopes-Lima et al 2020) as well as being known to occur in the Mekong Basin in Indochina (Haas 1969;Brandt 1974;Nahok et al 2017;Goncalves et al 2022). Consequently, the range of Cristaria, including C. plicata, covers the East Asian and Sundaland subregions, being a unique example of a unionid genus crossing the drainage divide between the Mekong and East Asian rivers (Bolotov et al 2018(Bolotov et al , 2020Goncalves et al 2022).…”

“…This author also noticed that "this species has semi-oval glochidia without hooks" and it "cannot be placed among Anodontinae as Haas (1969), Vokes (1967: 213) a.o. suggested" (Brandt 1974;Sayenko et al 2005;Goncalves et al 2022). Sayenko et al (2005) noted that what Brandt named C. plicata could be another taxon.…”