Genus Triplophysa Research Articles

Mitogenomic perspectives on the origin of Tibetan loaches and their adaptation to high altitude.

Tibetan loaches are the largest group of Tibetan fishes and are well adapted to the Tibetan Plateau. To investigate the origin of Tibetan loaches and their adaptations to the Tibetan Plateau, we determined 32 complete mitochondrial genomes that included 29 Tibetan loach species, two Barbatula species and Schistura longus. By combining these newly determined sequences with other previously published mitochondrial genomes, we assembled a large mitogenomic data set (11,433 bp) of 96 species in the superfamily Cobitoidea, to investigate the phylogenetic status of the genus Triplophysa. The resulting phylogeny strongly supported that the genus Triplophysa forms a monophyletic group within Nemacheilidae. Our molecular dating time suggests that the lineage leading to the Tibetan loaches and other loaches diverged approximately 23.5 Ma, which falls within the period of recent major uplifts of the Tibetan Plateau in the Early Miocene. Selection analyses revealed that the mitochondrial protein-coding genes of Tibetan loaches have larger ratios of nonsynonymous to synonymous substitutions than do those of non-Tibetan loaches, indicating that Tibetan loaches accumulated more nonsynonymous mutations than non-Tibetan loaches and exhibited rapid evolution. Two positively selected sites were identified in the ATP8 and ND1 genes.

The complete mitochondrial genome sequence of Triplophysa stenura (Teleostei, Cypriniformes): genome characterization and phylogenetic analysis

The nemacheilid genus Triplophysa is widely distributed in the Qinghai-Tibet Plateau and its adjacent areas. The complete mitochondrial genome of the loach Triplophysa stenura collected from the Peigucuo Lake was sequenced. The genome was 16,569 bp in length, including 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and a non-coding control region (D-loop). Most of the genes were encoded on the heavy strand, except for ND6 and eight tRNA genes. The overall base composition of T. stenura was 27.8% for A, 28.4% for T, 25.4% for C, 18.4% for G, with a slight A + T rich feature (56.2%). Phylogenetic analyses showed that all Triplophysa species clustered together and T. stenura formed a sister relationship with T. tibetana. The complete mitogenome data of T. stenura would provide essential information in understanding phylogenetic relationships among Triplophysa species.

The complete mtDNA genome of Triplophysa dorsalis (Cypriniformes, Balitoridae, Cobitoidea): genome characterization and phylogenetic analysis

Based upon the morphological characters, the genus Triplophysa (plateau Loach) is a highly diverse group in the family Balitoridae (or Cypriniformes, Cobitoidea) with 133 valid species. Therefore, the taxonomic relationship of this species at the genetic level remains ambiguous. In the present study, we sequenced the complete mitochondrial genome of Triplophysa dorsalis. In order to understand its position and genetic background at the gene level, the characteristics of mitochondrial DNA sequences and phylogenetic relationship were examined. The mitochondrial genome of T. dorsalis is similar to those of the typical vertebrates, 16 572 bp in length, including 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, and a non-coding control region (D-loop). All genes were encoded on the heavy strand except for ND6 and 8 tRNA genes. The overall base composition of the heavy strand was 28.16%, 28.41%, 25.62% and 17.82% for A, T, C and G, respectively. Phylogenetic analyses showed that the seven Triplophysa species clustered together with T. dorsalis to form a sister group with Triplophysa strauchii, T. bleekeri, T. stoliczkai and T. bombifrons. The two genera Triplophysa and Barbatula formed a sister-group relationship, the species Homatula potanini located in the intermediate position, and the genus Leptobotia elongata was in the basal position in the subfamily Nemacheilidae. Further investigations with more Triplophysa species need to be performed for better understanding of the evolutionary history of this fascinating genus.

Ten polymorphic microsatellite loci developed from Triplophysa anterodorsalis

Triplophysa anterodorsalis is a genus Triplophysa (Rendahl) fish which belongs to the family Balitoridae, subfamily Nemacheilinae. There are 112 nominal species in the genus Triplophysa all over the world, and ∼60% of species are found in China (Chen and Yang 2005; Froese R. and Pauly D. 2008 FishBase: www.fishbase.org, ver. (06/2008)). T. anterodorsalis is an endemic fish, distributed in upper reaches of the Yangtze river, Jinsha river and its tributaries (Ding 1994). But, since 2002, four cascade hydropower stations were under construction in the lower reaches of Jinsha river (Chen et al. 2005). Fragmentation caused by these dams might disrupt the connectivity of hydro-ecosystem and the gene flow between local fish populations (Fu et al. 2003; Jiang et al. 2007; Huang et al. 2011). Due to human activities, such as overfishing, dam construction, water contamination and habitat alteration, wild fisheries of this species have declined dramatically, and the distribution ranges have been shrinking rapidly in the last decades (Gao et al. 2011). In the long run, a good understanding of the genetic diversity, population structure and differentiation of T. anterodorsalis is required in order to establish adequate management plans for the conservation of this species. While the need for restoration of T. anterodorsalis, has been recognized, a eight-year management project based on population genetics has been initiated to define the efficiency of these conservation measures since 2011 (Yu and Chen 2011). In the present study, we isolated and characterized 10 microsatellites from T. anterodorsalis. These markers will be a useful tool for studies of population demographic history, genetic structure and conservation purposes in this species.

The complete mitochondrial genome sequence of Triplophysa bleekeri (Teleostei, Balitoridae, Nemacheilinae)

The genus Triplophysa (plateau loach) is a highly diverse group in the family Balitoridae with 133 valid species, and they play an important role in zoogeographic study of the Qinghai-Tibet Plateau. In this study, we sequenced the complete mitochondrial genome of a Triplophysa species, Triplophysa bleekeri. Combined with the complete mitogenome sequences of other 10 balitorids, the phylogenetic position of T. bleekeri was estimated. The mitochondrial genome of T. bleekeri is similar to those of the typical vertebrates, 16,568 bp in length, including 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, and 1 non-coding control region (D-loop). In the D-loop region, two pair of motifs, “TACAT” and its reverted and complemented sequence “ATGTA”, can be found in the domain of termination-associated sequence; six conserved sequences (CSB-F, CSB-E, CSB-D, and CSB I–III) can be identified by searching some conserved motifs. Phylogenetic analyses showed that the three Triplophysa species clustered together, with T. bleekeri sister to Triplophysa stoliczkai. The two genera Triplophysa and Barbatula formed a sister-group relationship, the genus Lefua located in the intermediate position, and the genus Schistura was in the basal position in the subfamily Nemacheilinae. Further investigations with more Triplophysa species included need to be performed to better understand the evolutionary history of this intriguing genus.

A new blind loach species, Triplophysa huanjiangensis (Teleostei: Balitoridae), from Guangxi, China.

A new blind loach of the genus Triplophysa was collected in 2007 from a cave in Leyi village, located near Chuanshan Town, Huangjiang County in the Guangxi Zhuang Autonomous Region of southern China. The new species, Triplophysa huangjiangensis sp. nov, can be distinguished from its congeners by eyes and scales absent; caudal-fin forked; adipose keel present; lips with furrows; distal margin of dorsal-fin truncate, dorsal fin origin much closer to caudal-fin base than snout tip; 8-9 branched dorsal-fin rays; 6-7 branched pelvic-fin rays; 6 branched anal-fin rays; 10-11 branched pectoral-fin rays; 13-14 branched caudal-fin rays; pectoral-fin length 52.3%-70.7% the distance between pectoral-fin origin to pelvic-fin origin; dorsal-fin origin posterior to vertical line of pelvic-fin origin; outer rostral barbel longer than other two pairs of barbels, with 47.0%-73.8% of lateral head length; anterior nostril with elongate barbel-like tip; and posterior chamber of gas-bladder developed, reaching pelvic-fin origin.

Morphological classification of loaches (Nemacheilinae)

Comprehensive comparative morphological analysis of loaches from the subfamily Nemacheilinae is conducted. Forty significant phylogenetic characters are suggested, and phylogenetic relationships are reconstructed. The subfamily Nemacheilinae is subdivided into five tribes (Vaillantellini, Lefuini nov., Yunnanilini nov., Triplophysini nov., and Nemacheilini), and the relationships between these tribes can be expressed by the following formula: Vaillantellini (Lefuini (Yunnanilini (Triplophysini + Nemacheilini))). The classification of highland Asian loaches (Triplophysini) is specified, and the revised diagnoses of the genera from this tribe are given. Heterogeneity of the genus Triplophysa is demonstrated. This genus can be divided into several subgenera, and three new subgenera (Labiatophysa subgen. nov., Indotriplophysa subgen. nov., and Tarimichthys subgen. nov.) are described. A new species Hedinichthys grummorum sp. n is described from the Turpan Depression (northwest China).

A New Blind Underground Species of the Genus <I>Triplophysa</I> (Balitoridae) from Yunnan, China

A new species of the genus Triplophysa was discovered in underground water of a cave near Nijiao Village, Qiubei County (24°05′N，104°01′E), Yunnan, China, in 2002 and 2006. The new species, Triplophysa qiubeiensis is similar to T. anterodorsalis Cao et Zhu (1989), and can be distinguished from all the cave-dwelling Triplophysa in China by the following characters: 1) eyes highly degenerated vs. eyes normal; 2) branched dorsal–fin ray 7 vs. 8－9; 3) caudal fin forked vs. emarginate. The new species is also similar to T. macromaculeta Yang (1990) from the same river system, Nanpan Jiang, but can be distinguished from the latter the following characters: 1) eyes highly degenerated vs. eyes normal; 2) without blotches vs. with blotches; 3) caudal fin forked vs. emarginate.

A brief review of Triplophysa (Cypriniformes: Balitoridae) species from the Tarim Basin in Xinjiang, China, with description of a new species

Recent fieldwork allows a revision of the loaches of the genus Triplophysa inhabiting the Tarim Basin in Xinjiang, China. Eleven species were previously recorded. T. stewarti is a new record. Triplophysa papilloso-labiatus should be regarded as a valid species name. Triplophysa laterimaculata sp. n. was collected from the Kezile River, a tributary of the Tarim River, Kashigar City, Xinjiang on August 22, 2004. The new species can be distinguished from its congeners by the following combination of the characters: body compressed posteriorly; origin of dorsal fin closer to caudal base than to snout tip; pelvic fin insertion below 2 nd– 3 rd branched dorsal rays, fins extending beyond anus or nearly reaching anal fin origin; caudal fin slightly emarginate; body scaleless; lateral line complete; lips thick with strong furrows and papillae remarkable at mouth angle; anterior margin of lower lip covering anterior margin of lower jaw; intestine with 2 coils; free posterior portion of air bladder nearly equal to eye diameter, connecting to anterior encapsulated portion with long tube.

Redescription of a fossil loach Triplophysa opinata (Yakowlew, 1959) from the Miocene of Kirgizia (Balitoridae: Nemacheilinae)

The only known fossil representative of the genus Triplophysa, T. opinata from the middle-upper Miocene of Kirgizia is redescribed. It is suggested that this species is closest to the species groups “dorsalis” and “labiata” (sensu Prokofiev, 2002, 2004a). The fossil finding clearly suggests that Triplophysa developed no later than in the middle of the Neogene.