Unraveling a 146 Years Old Taxonomic Puzzle: Validation of Malabar Snakehead, Species-Status and Its Relevance for Channid Systematics and Evolution

The current distribution of C. diplogramma and C. micropeltes is best explained by vicariance. The significant variation in the key taxonomic characters and the results of the molecular marker analysis points towards an allopatric speciation event or vicariant divergence from a common ancestor, which molecular data suggests to have occurred as early as 21.76 million years ago. The resurrection of C. diplogramma from the synonymy of C. micropeltes has hence been confirmed 146 years after its initial description and 134 years after it was synonymised, establishing it is an endemic species of peninsular India and prioritizing its conservation value

Morphological and Genetic Evidence for Multiple Evolutionary Distinct Lineages in the Endangered and Commercially Exploited Red Lined Torpedo Barbs Endemic to the Western Ghats of India

<div><p>Red lined torpedo barbs (RLTBs) (Cyprinidae: <i>Puntius</i>) endemic to the Western Ghats Hotspot of India, are popular and highly priced freshwater aquarium fishes. Two decades of indiscriminate exploitation for the pet trade, restricted range, fragmented populations and continuing decline in quality of habitats has resulted in their ‘Endangered’ listing. Here, we tested whether the isolated RLTB populations demonstrated considerable variation qualifying to be considered as distinct conservation targets. Multivariate morphometric analysis using 24 size-adjusted characters delineated all allopatric populations. Similarly, the species-tree highlighted a phylogeny with 12 distinct RLTB lineages corresponding to each of the different riverine populations. However, coalescence-based methods using mitochondrial DNA markers identified only eight evolutionarily distinct lineages. Divergence time analysis points to recent separation of the populations, owing to the geographical isolation, more than 5 million years ago, after the lineages were split into two ancestral stocks in the Paleocene, on north and south of a major geographical gap in the Western Ghats. Our results revealing the existence of eight evolutionarily distinct RLTB lineages calls for the re-determination of conservation targets for these cryptic and endangered taxa.</p></div

Results of the DNA based species delimitation methods.

<p>Results of the DNA based species delimitation methods a) Heat-map showing the fixed distance threshold method and the clustering of the specimens; b) results of the GMYC method implemented on the cytb and cox1+ cytb ultrametric trees, the coloured blocks on the right side indicates the tips clustered together by the program as a same (putative) species; c) Result of the Bayesian method applied on the RLTB species tree, values at nodes are the speciation probabilities using three different prior settings (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069741#s4" target="_blank">materials and methods</a> for details); each evolutionarily distinct lineage (tip) is denoted with a distinct colour.</p

Results of Divergence time analysis.

<p>Timetree showing the divergence times of the major RLTB lineages, node bars denote the 95% credibility interval; values at nodes indicate the mean age in million years.</p

Micro-level distribution of the eight evolutionarily distinct lineages (EDL) including the two recognized species of RLTBs in the Western Ghats.

1<p>The precise type locality of <i>P. denisonii</i> is still unclear. Three river systems, Periyar, Pampa and Achankovil drain the larger landscape in and around from where Francis Day described <i>P. denisonii</i><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069741#pone.0069741-Day1" target="_blank">[89]</a>.</p><p>Lineages in bold represent the most heavily collected locations of RLTBs, see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069741#pone.0069741.s008" target="_blank">figure S8</a>. Voucher specimen of the specimens examined in our study are currently deposited at the museum of the Conservation Research Group (CRG), Department of.</p><p>Aquaculture, St. Albert’s College, Kochi, India.</p

Map showing distribution range of RLTBs and rivers from where samples were collected.

<p>Map showing distribution range of RLTBs and rivers from where samples were collected, the species-tree built in *BEAST is shown on the left side. Posterior probability values below 1 are shown at the nodes. Photograph of a specimen considered as <i>Puntius denisonii</i> is shown; notice the absence of a black spot on the dorsal fin which is the current diagnostic character for distinguishing it from its congener <i>Puntius chalakkudiensis</i> found at location CHD in the map, the tip label codes are explained in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069741#pone-0069741-t001" target="_blank">Table 1</a>. Note that according to the current taxonomy of RLTBs <i>P. denisonii</i> (most probably population PER-D), is nested within the different populations of <i>P. chalakkudiensis,</i> the other populations of <i>P.denisonii</i> are distributed above the palaghat gap. Here we show that each of these populations (labeled) qualify as evolutionarily distinct lineages.</p

MANOVA/CVA discriminating different RLTB populations.

<p>MANOVA/CVA of 24 size adjusted biometric characters of 12 RLTB populations. (a) Clusters of all 12 populations on the first two canonical axis and (b) pair wise matrix of Fisher’s distances between the centroids of the clusters (upper diagonal) and P values for Fisher’s distances (lower diagonal). Percent discrimination by each canonical axis is shown in parenthesis.</p