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karyotypes of five belontiid fishes family belontiidae betta smaragdina b simplex b sp trichopsis pumila and t schalleri thawat donsakul wichian magtoon and achariya rangsiruji department of biology faculty of science srinakharinwirot university bangkok 10110 thailand 2n=42 1 2 18 48 2 5 14 56 2n=44 2 2 18 52 2n=46 1 22 48 23 46 abstract the purpose of this research was to investigate karyotypes of five belontiid fishes including betta smaragdina b simplex b sp trichopsis pumila and t schalleri chromosome preparations for karyotype analysis were obtained either from kidney tissues or gill epithelial tissues and stained with giemsa s stain results of this study were as follows betta smaragdina and b sp possessed the same diploid chromosome number of 2n=42 and their karyotypes comprised 1 pair of meta 2 pairs of submeta and 18 pairs of acrocentric chromosomes with the arm number nf of 48 2 pairs of meta 5 pairs of submeta and 14 pairs of acrocentric chromosomes with nf=56 respectively betta simplex had 2n=44 and karyotype comprised 2 pairs of meta 2 pairs of submeta and 18 pairs of acrocentric chromosomes with nf=52 for trichopsis pumila and t schalleri an identical diploid chromosome number of 2n=46 was obtained while the former s karyotype consisted of 1 pair of meta and 22 pairs of acrocentric chromosomes with nf=48 the latter possessed only 23 pairs of acrocentric chromosomes with nf=46 35th congress on science and technology of thailand 1

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introduction betta smaragdina ladiges 1972 b simplex kottelat 1994 b sp trichopsis pumila arnold in ahl 1937 and t schalleri ladiges 1962 are freshwater fishes which belong to the family belontiidae twelve genera and 46 species have been reported worldwide [1 in thailand there are about 15 species [2 and these fishes are commonly known as fighting fishes paradise fishes and combtail gauramies this research aimed to study karyotypes of the aforementioned five representatives in the family belontiidae methodology numbers and localities of each taxon of the fishes under study were given as follows betta smaragdina 10 specimens from udon thani and sakon nakhon provinces betta simplex 20 specimens from krabi province betta sp 10 specimens from jatujak sunday market trichopsis pumila 30 specimens from suphan buri province and trichopsis schalleri 10 specimens from nakhon sawan and sakon nakhon provinces these specimens were selected according to their standard lengths i.e b smaragdina 3.5-4.6 cm b simplex 4.5-4.6 cm b sp 4.5-5.5 cm t pumila 2.3-2.5 cm and t schalleri 2.9-3.5 cm identification of these fishes followed rainboth [3 kotellat [4 and vidthayanon [5 chromosomes were prepared either from kidney tissues or gill epithelial tissues and analyzed following methods modified from those of ida and kyo [6 classification of chromosomes was adapted from levan et al [7 based on their ratios of long arms and short arms the chromosomes were described as metacentrics 1.0-1.7 submetacentrics 1.7-3.0 subtelocentrics 3.0-7.0 and acrocentrics 7.0 metacentric and submetacentric types were described as biarmed chromosomes while subtelocentric and acrocentric types were described as monoarmed chromosomes [8 results discussion and conclusion results of this study are summarized in table 1 photographs of betta smaragdina b simplex b sp trichopsis pumila and t schalleri and photomicrographs of their karyotypes are shown in figures 1a 1b 1c 1d and 1e respectively table 1 diploid chromosome numbers 2n chromosome types and arm numbers of betta smaragdina b simplex b sp trichopsis pumila and t schalleri chromosome types m betta smaragdina betta simplex betta sp trichopsis pumila trichopsis schalleri 42 44 42 46 46 1 2 2 1 0 sm 2 2 5 0 0 st 0 0 0 0 0 t 18 18 14 22 23 arm numbers nf 48 52 56 48 46 species 2n note m metacentric sm submetacentric st subtelocentric t acrocentric or telocentric chromosomes 35th congress on science and technology of thailand 2

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figure 1 photographs of betta smaragdina a betta simplex b betta sp c trichopsis pumila d trichopsis schalleri e and photomicrographs of their karyotypes each scale bar represents 5 m abbreviations m sm st and t denote metacentrics submetacentrics subtelocentrics and acrocentrics respectively the present study showed that betta smaragdina possessed the diploid chromosome number 2n of 42 with the karyotype consisting of 1 pair of metacentric m 2 pairs of submetacentric sm and 18 pairs of telocentric chromosome t with the arm number nf of 48 betta simplex had 2n=44 and comprised 2m+2sm+18t pairs nf=52 betta sp had 2n=42 and composed of 2m+5sm+14t pairs nf=56 trichopsis pumila had 2n=46 and contained 1m+22t pairs nf=48 trichopsis schalleri had 2n=46 and only consisted of 23 pairs of acrocentric chromosomes nf=46 results of this study revealed that betta smaragdina and betta sp possessed an identical diploid chromosome number of 2n=42 but with different karyotypes this diploid chromosome number was also found in b splendens 2n=42 2m 4sm 15t pairs [9 betta simplex on the other hand had 2n=44 all of these taxa had different diploid chromosome numbers from b prima 2n=34 2m +2sm 2st 11t pairs [9 trichopsis pumila and t schalleri possessed 2n=46 the same diploid chromosome 35th congress on science and technology of thailand 3

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number was also reported previously in t vittatus 2n=46 23t pairs [9 since both t schalleri and t vittatus contained similar chromosome number and karyotype these species should be regarded as closely related within the family bolontiidae it was observed that trichogaster trichopterus also possessed 2n=46 with 23 pairs of acrocentric chromosomes [9 this is the first report of karyological study in betta smaragdina b simplex b sp trichopsis pumila and t schalleri references 1 j s nelson fishes of the world 1994 600 p 2 c vidthayanon diversity of freshwater fishes in thailand 1997 102 p 3 w j rainboth fish of the cambodian mekong 1996 265 p 4 m kotellat fishes of laos 2001 198 p 5 c vidthayanon manual of freshwater fishes 2004 231 p 6 h ida and y kyo japanese journal of ichthyology 1980 27 122-128 7 a levan k fredga and a a sandberg hereditas 1964 52 201-220 8 r arai bulletin natural science museum ser a 1982 16 405-408 9 t donsakul a rangsiruji and w magtoon 33rd congress on science and technology of thailand 2007 b3-b0064 keywords betta smaragdina betta simplex betta sp trichopsis pumila trichopsis schalleri karyotype 35th congress on science and technology of thailand 4

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