Mitochondrial COI and nuclear RAG1 DNA sequences and analyses of specimens of the three morphologically established species in the genus Trichopsis (Perciformes: Osphronemidae) reveal new/cryptic species

Abstract

Air-breathing fish species of the genus Trichopsis have been reported in Cambodia, Lao PDR, Indonesia, Malaysia, Singapore, Thailand and Vietnam. It is only in Thailand that all three recognized species (Trichopsis vittata, Trichopsis schalleri and Trichopsis pumila), as judged by distinct external features, are found. Cambodia and Lao PDR harbor two species each. The present work involves first-time DNA sequencing and analysis based on mitochondrial (COI) and nuclear (RAG1) DNA of numerous specimens of these species and specimens of a controversial Phetchaburi (Thailand) fish population with a mixed outward appearance. In addition to confirming the morphologically clear-cut taxonomic division of the three fish species, our DNA results show that whereas the T. pumila populations form one single species, there are cryptic species in the T. vittata and T. schalleri populations and possibly a new one in the latter. Members of the putative Phetchaburi fish population have been proven to be hybrids between T. pumila and T. vittata. In addition, a new the phylogenetic tree indicating ancestral relationships is also presented. This study should generate further research to find new/cryptic species of the genus Trichopsis in all countries harboring the fish.

First records of Croaking Gourami, Trichopsis vittata (Cuvier, 1831) (Teleostei: Osphronemidae), from Myanmar and Bangladesh

“…vittata) 3" (BIN cluster ID BOLD:ACS9775), from western and central Thailand, but dissimilar (> 2.4% p-distance) to all individuals of T. vittata from other areas. This supports the conclusion by Panijpan et al (2015) that the current T. vittata is a species complex, and indicates that T. vittata sold in the ornamental fish trade in Europe and the introduced populations in Bangladesh and Myanmar all originates from central and western Thailand. According to Panijpan et al (2015), "Trichopsis sp.…”

“…The COI sequences of T. vittata from Myanmar, Bangladesh, and the ornamental fish trade are similar (≤ 0.6% p-distance) to each other and to 78 published COI sequences, corresponding to a clade Panijpan et al (2015) referred to as "Trichopsis sp. (cf.…”

“…No T. vittata were found in southeastern Bangladesh (Chittagong Division) during a survey in 2015, or in northeastern Bangladesh (Sylhet Division), surveyed in 2016, despite the presence of suitable habitat. Panijpan et al (2015) analyzed mitochondrial COI and nuclear RAG1 DNA sequences of a large number of Trichopsis from Southeast Asia, and found that T. vittata is not a single species but a species complex comprising 4 ecologically and morphologically similar but genetically distinct biological species. However, there were no DNA sequences available from Java, the type locality of T. vittata (Roberts 1996), and Panijpan et al (2015) were unable to determine which, if any, of these 4 clades represented the true T. vittata.…”

“…Panijpan et al (2015) analyzed mitochondrial COI and nuclear RAG1 DNA sequences of a large number of Trichopsis from Southeast Asia, and found that T. vittata is not a single species but a species complex comprising 4 ecologically and morphologically similar but genetically distinct biological species. However, there were no DNA sequences available from Java, the type locality of T. vittata (Roberts 1996), and Panijpan et al (2015) were unable to determine which, if any, of these 4 clades represented the true T. vittata. Dahruddin et al (2016) published 6 sequences of T. vittata from Java, which in our analysis correspond to the clade that Panijpan et al (2015) referred to as "Trichopsis cf.…”

“…However, there were no DNA sequences available from Java, the type locality of T. vittata (Roberts 1996), and Panijpan et al (2015) were unable to determine which, if any, of these 4 clades represented the true T. vittata. Dahruddin et al (2016) published 6 sequences of T. vittata from Java, which in our analysis correspond to the clade that Panijpan et al (2015) referred to as "Trichopsis cf. vittata 4", from southern Thailand (BIN cluster ID BOLD:AAB9368).…”