Comparative study on karyotypes of three Mastacembelus species (Synbranchiformes: Mastacembelidae) from Thailand

WATCHARIN SEREE (Program of Applied Science, Faculty of Interdisciplinary Studies, Khon Kaen University, Nong Khai Campus. 112 Village No. 7, Mittraphap Road, Nong Kom Ko, Muang 43000, Nong Khai, Thailand)
WEERAYUTH SUPIWONG (Program of Applied Science, Faculty of Interdisciplinary Studies, Khon Kaen University, Nong Khai Campus. 112 Village No. 7, Mittraphap Road, Nong Kom Ko, Muang 43000, Nong Khai, Thailand)
GETLEKLA NUNTAPORN (Department of Biology, Faculty of Science and Technology, Muban Chombueng Rajabhat University. 46 Village No. 3, Chom Bueng, Chom Bueng 70150, Ratchaburi, Thailand)
SUKHONTHIP DITCHAROEN (Department of Biology, Faculty of Science, Khon Kaen University. 123 Mittraparb Road, Nai-Muang, Muang 40002, Khon Kaen, Thailand)
NATTHASUDA DONBUNDIT (Department of Biology, Faculty of Science, Khon Kaen University. 123 Mittraparb Road, Nai-Muang, Muang 40002, Khon Kaen, Thailand)
KRIENGKRAI SEETAPAN (Department of Fishery, School of Agriculture and Natural Resources, University of Phayao. 19 Moo 2 Tambon Maeka, Amphur Muang Phayao 56000 Thailand)
SAMPAN TONGNUNUI (Department of Conservation Biology, Mahidol University, Kanchanaburi Campus. 199 Lumsum Saiyok 71150, Kanchanaburi, Thailand)
SITTHISAK JUNTHARAT (Department of Science, Faculty of Science and Technology, Prince of Songkla University, Pattani Campus, Mueng 94000, Pattani, Thailand)
ALONGKLOD TANOMTONG (Department of Biology, Faculty of Science, Khon Kaen University. 123 Mittraparb Road, Nai-Muang, Muang 40002, Khon Kaen, Thailand)

Biodiversitas Journal of Biological Diversity
Vol. 26 No. 1 (2025)

Abstract. Seree W, Supiwong W, Nuntaporn G, Ditcharoen S, Donbundit N, Seetapan K, Tongnunui S, Juntharat S, Tanomtong A. 2025. Comparative study on karyotypes of three Mastacembelus species (Synbranchiformes: Mastacembelidae) from Thailand. Biodiversitas 26: 246-254. Karyotype study or chromosomal study is necessary for some cases of fish taxonomy. The chromosomes of three Mastacembelus species named Zig-zag eel or Mastacembelus armatus, Fire eel or Mastacembelus erythrotaenia, and Tire track eel or Mastacembelus favus using conventional Giemsa staining and Ag-Nucleolar Organizer Region (NOR) banding techniques were investigated. The results indicated that conserved diploid number (2n) of 48 and the fundamental number or chromosome arm number (NF) as 62 for all analyzed species of male and female specimens were revealed, although varying in their karyotype structures were observed. Karyotypes of three species are as follows: 12m+2sm+2a+32t, 10m+6sm+32t, and 8m+6sm+34t in M. armatus, M. erythrotaenia, and M. favus, respectively. In each species, positive Ag-NOR markers were differentially observed adjacent to telomeric and/or sub-telomeric regions (telomeric NORs) of metacentric or submetacentric chromosomes. In M. armatus, NOR locations are at the long arm of the first metacentric chromosome pair, while in M. favus and M. erythrotaenia, NOR locations are at the short arm of the first submetacentric chromosome and the first metacentric chromosome pairs, respectively. The findings show that Mastacembelus species, despite having a conserved diploid number, differ remarkably in the patterns of Nucleolar Organizer Regions (NORs) in their karyotypes. These species-specific patterns can be useful in further characterizing and identifying different species and investigating the evolutionary mechanisms driving the evolution of these fish karyotypes.