Macrobrachium chainatense sp. nov. (Decapoda: Palaemonidae): a freshwater prawn from Thailand based on morphology and molecular phylogeny

Abstract

Many species of freshwater prawns, large and small, inhabit Southeast Asian countries. In Thailand alone, there have been recent reports of new species in the genus Macrobrachium. Morphological differentiation and, recently, DNA sequence differences have been used to distinguish new species from valid ones. Macrobrachium chainatense (Decapoda: Palaemonidae), a small freshwater prawn found in Thailand, is now established as a new species based on both morphological and genetic criteria. Among Thailand Macrobrachium prawns, M. chainatense has smallest body size, largest egg size, and 3–5 teeth on the cutting edges. The most closely related Macrobrachium species to M. chainatense in terms of COI and 18S DNA sequences is M. niphanae. Their COI sequences differ by 7.3% while their 18S sequences are basically identical in all but one site. Observations of some aspects of this prawn in captivity are also utilized to establish its unique species status. This prawn may be useful as a source of cooked food for human consumption.

Peer Review #1 of "Molecular phylogeny and species delimitation of the freshwater prawn Macrobrachium pilimanus species group, with descriptions of three new species from Thailand (v0.1)"

“…In the past, Thai freshwater prawn and shrimp fauna were referred to in some taxonomic revisions among the oriental crustacean fauna (Holthuis 1950;Holthuis 1955;Johnson 1963). Twenty-eight described species of freshwater prawns of the genus Macrobrachium Spence Bate, 1868 have been reported in Thailand (Cai et al 2004;Naiyanetr 2001;Naiyanetr 2007;Saengphan et al 2018;Saengphan et al 2019). All Macrobrachium species in Thailand are found abundantly within two major riverine systems, namely the Chaophraya and Greater Mekong Basins, as reported by previous taxonomic studies (Cai & Ng 2002;Hanamura et al 2011).…”

“…Three standard molecular loci for Macrobrachium were selected for phylogenetic study, including the barcode regions of mitochondrial cytochrome c oxidase subunit I (COI), 16S rRNA (16S), and nuclear 18S rRNA (18S). The criteria for DNA marker selection were 1) sequences of closely related taxa for sequence comparison are available in a public database such as GenBank and BOLD ((Liu et al 2007;Wowor et al 2009), 2) marker is commonly used for phylogenetic tree reconstruction of genus Macrobrachium (Rossi et al 2020;Saengphan et al 2018;Saengphan et al 2019) and 3) a sufficient amount of variation, conserved and parsimony informative sites for multi-locus phylogenetic study (Liu et al 2017;Matzen da Silva et al 2011;Pileggi & Mantelatto 2010). The PCR primers used in amplification and sequencing are presented in Table 2.…”

“…Previously, the study of freshwater prawn genus Macrobrachium mainly focused on the commercial species due to their economic value both globally and at a local scale (New & Nair 2012). Recently, two newly named species, M. suphanense and M. chinatense were described from freshwater tributaries in central Thailand (Saengphan et al 2018;Saengphan et al 2019). There is also some genetic evidence of Thai Macrobrachium species exhibiting distinct geographical populations (Khanarnpai et al 2019;Saengphan et al 2018).…”

“…Systematic studies of Asian shrimp and prawn species have been increasingly pursued due to evidence of unreported species and underestimation of genetic diversity (Bernardes et al 2017;de Bruyn & Mather 2007;de Mazancourt et al 2019;von Rintelen et al 2007). New native species have been reported from several remote areas throughout both continental and insular Asia (Cai & Ng 2002;Chong 1989;Saengphan et al 2018;Saengphan et al 2019;Wowor & Short 2007;Xuân 2012).…”

Molecular phylogeny and species delimitation of the freshwater prawnMacrobrachium pilimanusspecies group, with descriptions of three new species from Thailand

“…Systematic studies of Asian shrimp and prawn species have been increasingly pursued due to evidence of unreported species and underestimation of genetic diversity ( Bernardes et al, 2017 ; De Bruyn & Mather, 2007 ; De Mazancourt et al, 2019 ; Von Rintelen, Von Rintelen & Glaubrecht, 2007 ). New native species have been reported from several remote areas throughout both continental and insular Asia ( Cai & Ng, 2002 ; Chong, 1989 ; Saengphan et al, 2018 ; Saengphan et al, 2019 ; Wowor & Short, 2007 ; Xuan, 2012 ).…”