Triplophysa sanduensis, a new loach species of nemacheilid (Teleostei: Cypriniformes) from South China.

A new species of Nemacheilidae, Triplophysa sanduensis sp. nov., is described here based on specimens collected from a small cave in Dengguang Village, Zhonghe Town, Sandu County, Guizhou Province, China. The new species can be distinguished from its congeners by the following combination of characters: branched dorsal-fin rays 8-9; branched pectoral-fin rays 8-9; branched pelvic-fin rays 5; branched anal-fin rays 5; vertebrae 4+37; snout length 45.5-50.1% of head length; postdorsal length 39.0-42.8% of standard length; caudal-peduncle depth/caudal-peduncle length range from 56.4% to 71.9%; the posterior chamber of the gas bladder degenerated; body elongated, covered by scattered scales; eyes present and normal in size, not reduced or absent; and a complete lateral line. A phylogenetic analysis based on the mitochondrial cytochrome oxidase subunit 1 (COI) gene resolved Triplophysa sanduensis as sister to Triplophysa longliensis. Kimura's 2-parameter genetic distance of the COI gene sequences between these two species was 1.9%.

Lanlabeo duanensis, a new genus and species of labeonin fish (Teleostei: Cyprinidae) from southern China.

Lanlabeo, a new genus of fish belonging to the family Cyprinidae, is described from the Pearl River drainage basin in Guangxi Province, southern China. This new genus is distinguished from all other genera of the cyprinid tribe Labeonini by a combination of morphological and phylogenetic characters. It differs morphologically from all other Asian labeonins in its uniquely modified oromandibular morphology. For example, this genus has a frenum connecting the upper jaw and lower lip at the corner of the mouth, regularly arranged papillae densely scattered over the ventral margin of the rostral cap, a vestigial upper lip, a rostral cap overlying the upper jaw and with a fimbriate posterior margin, and a lower lip divided into two lateral fleshy lobes and one central plate. These two lateral fleshy lobes are small and translucent, and the median lobe of the lower lip is large and has papillae regularly arranged in many transverse rows. In the lower jaw, the dentary is transversely L-shaped in ventral view because its anterior part forms a right-angle turn and its transverse branch is anterioposteriorly expanded. In addition, analyses of four nuclear gene datasets indicate that this new genus forms a highly divergent lineage within the Labeonini, and that Lanlabeo is closely related to the genus Ptychidio. Therefore, based on morphometric differences and phylogenetic relationships, we describe this new genus herein as Lanlabeo, containing the new species Lanlabeo duanensis.

Metzia parva, a new cyprinid species (Teleostei: Cypriniformes) from south China.

A new species of a small cyprinid fish, Metzia parva sp. nov., is described here based on specimens collected from a tributary of Hongshui-He River in the Pearl River basin at Anyang Town, Du'an County, Guangxi Province, south China. It differs from congeners in having a smaller body with a standard length of 48.3-57.7 mm (vs. 58.3-151.4 mm in other species); a complete lateral line (although some specimens show interruptions on the ventral margin above the anal-fin); 12-14 branched anal-fin rays (vs. 10-11 or 15-20); 10 branched pectoral-fin rays (vs. 11-16); 6 branched pelvic-fin rays (vs. 7-9); a longer caudal peduncle (17.8-21.7% vs. 14.8-17.4% SL); a shorter preanal length (60.9-66.0% vs. 69.0-73.0% SL) and an obviously larger interorbital width (28.4-33.0% vs. 20.2-24.7% of head length). While Metzia parva shares a lateral black stripe from the gill opening to the caudal-fin base with M. formosae, the new species can be distinguished from M. formosae by a deeper head (16.4-19.2% vs. 13.3-15.7% SL) and a longer anal fin (15.4-18.9% vs. 10.0-13.6% SL) in addition to the diagnostic characters above. Kimura's 2-parameter genetic distance between the two species is 6.6% for the barcoding region of the mitochondrial COI gene and 7.3% across the complete mitochondrial genome.

Paraqianlabeo lineatus, a new genus and species of labeonine fishes (Teleostei: Cyprinidae) from South China.

Paraqianlabeo, new genus, is described from the Chishui-He and Wu-Jiang rivers of the Yangtze River basin in Guizhou Province, South China. This new genus is distinguished from all other labeonine genera by a combination of morphological and molecular evidence. It is distinguished from all other Asian garrains by a unique oromandibular morphology; i.e., an arched, wide, rudimentary sucker formed by raised front and lateral margins of lower lip, postlabial groove and mental groove between middle and lateral lobes of lower lip chevron-shaped; anteroventral margin of rostral cap arched, thin and papillose; rostral cap not overlying upper lip, upper lip connected with lower lip around corners of mouth; well developed upper lip free from upper jaw; lower lip divided into two lateral fleshy lobes and one central plate, these two lateral fleshy lobes small and short, median lobe of lower lip large; anterior and anterolateral edges of upper and lower lip finely papillose; shallow, straight groove between lower lip and lower jaw; lower jaw bears thin, cornified cutting edge. Additionally, scales on mid-ventral region from pectoral fins to pelvic fins subcutaneous and half-hidden; dorsal fin with 3 simple and 7½-8 branched rays. Paraqianlabeo lineatus, new species, type species of this genus, has longitudinal dark stripe along side of body. Analyses of mitochondrial DNA data indicate that this new genus forms a highly diverged lineage within the Garraina group of Labeoninae. 

The youngest split in sympatric schizothoracine fish (Cyprinidae) is shaped by ecological adaptations in a Tibetan Plateau glacier lake.

Although new empirical evidence shows that sympatric speciation has occurred in some species, there are few indisputable model organisms for this process of speciation. The two subspecies (Gymnocypris eckloni eckloni and G. e. scoliostomus) of the schizothoracine Gymnocypris fish species complex from a small glacier lake in the Tibetan Plateau, Lake Sunmcuo, fit several of the key characteristics of the sympatric speciation model. We used combined mitochondrial control region sequences and the cytochrome b gene (1894 bp) to address the phylogenetics and population genetics of 232 specimens of G. e. eckloni and G. e. scoliostomus, as well as all of its closely related sister species. We found that: (i) a total of four old lineages were uncovered in the widespread G. e. eckloni, of which only one was shown to be shared with all G. e. scoliostomus individuals and (ii) the new subspecies (G. e. scoliostomus) evolved in Lake Sunmcuo from the ancestral G. e. eckloni population within approximately 0.057 Ma. These two taxa of the species complex are morphologically distinct, and reproductive isolation is further suggested. Ecological disruptive selection based on morphological traits (e.g. mouth cleft characters) and food utilization may be a mechanism of incipient speciation of two sympatric populations within Lake Sunmcuo. This study provides the first genetic evidence for sympatric speciation in the schizothoracine fish.

[Phylogeny of chinese catfishes inferred from mitochondrial cytochrome b sequences].

The mitochondrial DNA cytochrome b gene was sequenced from 27 catfish species representing 11 families and 24 genera catfishes in China. Aligning with cytochrome b sequences of eight catfish species from North America and Africa retrieved from GenBank, and selecting Astyanax mexicanu, Cyprinus carpio, and Sardinops melanostictus as outgroups, we constructed a matrix of 38 DNA sequences. The phylogenetic trees were constructed by using Bayesian method and Maximum Parsimony (MP) method. The results showed that (1) there are three base pair deletions of mitochondrial cytochrome b gene compared with Characiformes, Cypriniformes, and Clupeiformes; (2) the representatives of Chinese catfish species form a monophyletic group; and (3) the molecular phylogenetic trees constructed with both methods suggest that the families Sisoridae, Akysidae and Amblycipitidae form a monophyletic group, and the families Clariidae, Schilbidae, Ariidae, Ictaluridae, Cranoglanididae, Pangasiidae, Siluridae, Claroteidae, and Bagridae also form a monophyletic group. The families Cranoglanididae from China and Ictaluridae from North America form a sister-group relationship, and the families Clariidae, Ictaluridae, Siluridae, and Sisoridae are obviously monophyletic groups. But the position of the family Plotosidae was not resolved by Bayesian analysis and maximum parsimony inference.