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A. Caridina cf. rangoona, from Phang Nga Province, Takuatung District, Khum Mut Stream; B. C. johnsoni, from Surat Thani Province, Mueang District, Phunphin Stream; C, D. C. nangroma sp. nov. from Chumphon Province, Lamae District, Lamae Stream; E, F. C. srivijaya sp. nov., from Surat Thani Province, Phrasaeng District, Bang Sawan Spring; G. C. takkola sp. nov., from Surat Thani Province, Mueang District, Phunphin Stream; H. C. tambralinga sp. nov., from Songkhla Province, Ranot District, Thale Noi NHA. Macharoenboon, von Rintelen, Klotz, Sutcharit, Siriwut & Jeratthitikul, 2026 |
Abstract
A comprehensive taxonomic review of the genus Caridina in southern Thailand is presented, integrating extensive field surveys with comprehensive morphological and molecular analyses to document the species diversity. Phylogenetic tree reconstructed from partial sequences of two mitochondrial genes (16S rRNA and COI) indicated 18 distinct lineages, recognized as species in our study, belonging to six species groups, from southern Thailand. Five of these are new to science and are described as Caridina kuehnei sp. nov., C. nangroma sp. nov., C. srivijaya sp. nov., C. takkola sp. nov., and C. tambralinga sp. nov. Including historical records, there are 21 species of Caridina found in southern Thailand of which almost half are endemic to the region. Updated distribution maps and a key to all known species in the region are also provided. Our findings highlight that while morphological identification is challenging due to significant intraspecific variation and interspecific similarity, molecular data is essential for helping taxonomists to delineate species boundaries.
Key words: Amphidromous, crustacean, freshwater fauna, landlocked, Malay Peninsula, molecular phylogeny, Thailand
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| Living specimens of Caridina species. A. C. thai, topotype MUMNH-CAR861-F1 from Nakhon Ratchasima Province, Pak Chong District, Muak Lek Waterfall; B, C. C. gracillima, specimens; B. MUMNH-CAR626-P1 from Trang Province, Mueang District, Trang River; C. MUMNH-CAR631-P1 from Krabi Province, Mueang District, Tha Hindarn Stream; D. C. gracilipes, specimen MUMNH-CAR462-P1 from Nakhon Si Thammarat Province, Khanom District, Khao Phlai Dam; E. C. macrophora, specimen MUMNH-CAR800 from Nakhon Si Thammarat Province, Bang Khan District, Lam Dang Stream; F. C. peninsularis, specimen MUMNH-CAR633-P1 from Phang Nga Province, Khum Mut Stream; G. C. excavatoides, specimen MUMNH-CAR616-F2 from Nakhon Sri Thammarat Province, Thung Song District, Tha-Luang Stream; H. C. temasek, specimen MUMNH-CAR835-P1 from Pattani Province, Mueang District, Pattani River. Scale bar: 4 mm. |
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| Living specimens of Caridina species. A. C. cf. rangoona, specimen MUMNH-CAR434-P1 from Phang Nga Province, Takuatung District, Khum Mut Stream; B. C. johnsoni, specimen MUMNH-CAR471-P1 from Surat Thani Province, Mueang District, Phunphin Stream; C, D. C. nangroma sp. nov.; C. paratype MUMNH-CAR404-P1 and D. specimen MUMNHCAR474-P1 from Chumphon Province, Lamae District, Lamae Stream; E, F. C. srivijaya sp. nov., paratypes; E. MUMNH-CAR502-P1; F. MUMNH-CAR502-M1; G. C. takkola sp. nov., paratype MUMNH-CAR469-P1; H. C. tambralinga sp. nov., specimen MUMNH-CAR489-P1 from Songkhla Province, Ranot District, Thale Noi Non-Hunting Area. Scale bar: 3 mm. |
Caridina kuehnei sp. nov.
C. nangroma sp. nov.
C. srivijaya sp. nov.
C. takkola sp. nov.
C. tambralinga sp. nov.
Kongkit Macharoenboon, Thomas von Rintelen, Werner Klotz, Chirasak Sutcharit, Warut Siriwut and Ekgachai Jeratthitikul. 2026. A Taxonomic Review of the freshwater shrimp Genus Caridina H. Milne Edwards, 1837 (Decapoda, Atyidae) from southern Thailand, with Descriptions of Five New Species. ZooKeys. 1292: 1-126. DOI: doi.org/10.3897/zookeys.1292.193168 [15 Sep 2026]
