Unexpected species diversity within Sri Lanka's snakehead fishes of the Channa marulius group (Teleostei: Channidae).

The taxonomic status of the large snakeheads of the Channa marulius group that occur in Sri Lanka is reviewed and clarified. Two species are recognized from the island, based on both morphological and molecular (cytochrome c oxidase subunit 1: cox1) differentiation: C. marulius Hamilton from the northern dry zone and C. ara Deraniyagala from the middle and lower regions of the Mahaweli basin. Channa ara is endemic to Sri Lanka and can be distinguished from its Marulius group congeners, C. marulius, C. aurolineata and C. auroflammea, by having fewer dorsal- and anal-fin rays, fewer lateral-line scales and fewer vertebrae; from C. marulioides by a different adult colour pattern; and from C. pseudomarulius by having more vertebrae. At the cox1 barcoding locus, Channa ara is at least 3.6% genetically different from C. marulius, and at least 8% different from the other described species in the group. Specimens collected from the southwestern wet zone in Sri Lanka are a puzzling third component of the Marulius group's diversity, uncovered in this study, and identified here as C. cf. ara. Whilst genetically more similar to C. marulius, C. cf. ara possesses fewer dorsal- and anal-fin rays, fewer lateral-line scales and fewer vertebrae and is therefore morphologically more similar to C. ara. Channa ara can be distinguished from C. cf. ara, however, by differences in circumpeduncular scale count, adult colour pattern, and by an uncorrected pairwise genetic distance of 3.7% in cox1 sequences. A neotype is designated for Ophicephalus marulius ara Deraniyagala.

Channa auroflammea, a new species of snakehead fish of the Marulius group from the Mekong River in Laos and Cambodia (Teleostei: Channidae).

Channa auroflammea is a new freshwater fish species of the Marulius group from the Mekong River system. Previously reported as C. marulius, C. cf. marulius, or C. aff. marulius, C. auroflammea is readily distinguished from C. marulius and other members of the Marulius group by a different colour pattern, and a DNA barcode sequence at least 6.5% divergent from other members of the group. Comparison of counts of vertebrae, dorsal-fin rays, and lateral-line scales reveals that these counts are lower in the Mekong C. auroflammea than in C. aurolineata from the Salween and Irrawaddy-Chindwin, higher than in the Marulius group species C. pseudomarulius and C. marulioides, but similar to those in C. marulius. Channa auroflammea is known from the Mekong river and tributaries in Laos and Cambodia, where it forms a regular component of the wild fisheries catch from the rivers Tonle San and Tonle Srepok. Literature records of Channa marulius from China appear to be based on confusion originating with Cuvier's description of Ophiocephalus grandinosus.

The snakehead fish Channa aurolineata is a valid species (Teleostei: Channidae) distinct from Channa marulius.

Channa aurolineata is a valid species of the Marulius group. Previously treated as a synonym of C. marulius, C. aurolineata is readily distinguished from C. marulius by a different colour pattern, in which a conspicuous white posterior margin is present on the black scales that form the dark lateral blotches in larger juveniles and adults (vs. scales without white margin but with white spots in C. marulius). Channa aurolineata also differs from C. marulius by having more lateral line scales (65-71 vs 62-65), more dorsal-fin rays (55-58 vs 52-56) and more vertebrae (63-66 vs 59-63). In addition to these morphological differences, C. aurolineata is genetically more than 8% different (uncorrected p-distance) from C. marulius at the COI barcoding gene, a difference consistent with levels of genetic divergence observed among different species. The same characters that distinguish C. aurolineata from C. marulius also distinguish it from C. pseudomarulius, the other Indian member of the Marulius group. Channa aurolineata has a widespread distribution in larger rivers in Myanmar, including the Chindwin, Ayeyarwaddy, Sittaung and Thanlwin river basins. The Indo-Burman ranges appear to delineate the western geographical limit of this species, with C. marulius restricted to the western side of this mountain chain.

DNA barcoding of Malaysian commercial snapper reveals an unrecognized species of the yellow-lined Lutjanus (Pisces:Lutjanidae).

Management of wild fisheries resources requires accurate knowledge on which species are being routinely exploited, but it can be hard to identify fishes to species level, especially in speciose fish groups where colour patterns vary with age. Snappers of the genus Lutjanus represent one such group, where fishes can be hard to identify and as a result fisheries statistics fail to capture species-level taxonomic information. This study employs traditional morphological and DNA barcoding approaches to identify adult and juvenile Lutjanus species harvested in Malaysian waters. Our results reveal a suite of species that differs markedly from those that have previously been considered important in the Malaysian wild-capture fishery and show that official fisheries statistics do not relate to exploitation at the species level. Furthermore, DNA barcoding uncovered two divergent groups of bigeye snapper ('Lutjanus lutjanus') distributed on either side of the Malay Peninsula, displaying a biogeographical pattern similar to distributions observed for many co-occurring reef-distributed fish groups. One of these bigeye snapper groups almost certainly represents an unrecognized species in need of taxonomic description. The study demonstrates the utility of DNA barcoding in uncovering overlooked diversity and for assessing species catch composition in a complicated but economically important taxonomic group.

Exploring hidden diversity in Southeast Asia's Dermogenys spp. (Beloniformes: Zenarchopteridae) through DNA barcoding.

Members of the freshwater halfbeak genus Dermogenys are hard to identify to the species level, despite several previous attempts to isolate fixed meristic, morphometric and colour pattern differences. This has led to ongoing confusion in scientific literature, records of species occurrence, and entries in museum collections. Here, a DNA barcoding study was conducted on the genus to gain further understanding of its taxonomic status across the Southeast Asian region. Fish were collected from 33 localities, spanning freshwater and brackish habitats in Malaysia, Western Indonesia, Thailand and Vietnam. In total, 290 samples of Dermogenys spp. were amplified for a 651 base pair fragment of the mitochondrial cytochrome oxidase c subunit I (COI) gene. Analysis was able to successfully differentiate the three species: D. collettei, D. siamensis, D. sumatrana; reveal the presence of a new putative species, Dermogenys sp., that was sampled in sympatry with D. collettei at three locations; as well as uncovering two genetic lineages of a fifth species, D. bispina, that display non-overlapping geographical distributions in drainages of northern Borneo; Kudat and Sandakan. This study expands the barcode library for Zenarchopteridae, demonstrates the efficacy of DNA barcoding techniques for differentiating Dermogenys species, and the potential thereof in species discovery.

A reappraisal of the evolution of Asian snakehead fishes (Pisces, Channidae) using molecular data from multiple genes and fossil calibration.

Freshwater snakehead fishes (Channidae) provide an interesting target for phylogenetic analysis for the following reasons, their unusual biology, potential for cryptic diversity and availability of a good fossil record. Here, a multi-locus molecular phylogeny was constructed and calibrated using two fossil dates to estimate divergence times within the family. Sampling aimed to explore interspecific divergence of Channa species across Southeast Asia and intra-specific variation where species possessed natural geographical ranges that were extensive. Results contradict divergence times estimated previously independently from single locus mitochondrial data or the fossil record and suggest that after divergence from African taxa 40-50 Ma, evolution of Asian snakeheads has been heavily influenced by multiple broad scale dispersal events across India and Southeast Asia. A similar pattern of divergence within multiple clades suggests that west-east dispersal was limited for many taxa during the Miocene. Deep intra-specific divergence was inferred for C. striata, indicating that long historical periods of isolation ( approximately 8Ma) have not resulted in the evolution of reproductive isolation within this species. Results support suggestions that C. marulia like fishes in northern Cambodia may constitute an undescribed species, and that Indian C. diplogramma warrants taxonomic recognition as being distinct from Southeast Asian C. micropeltes, with the two taxa last sharing a common ancestor in the mid- to late-Miocene.