| Channa diplogramma | |
|---|---|
| Malabar snakehead, Channa diplogramma | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Perciformes |
| Family: | Channidae |
| Genus: | Channa Scopoli, 1777 |
| Species: | Channa diplogramma Day, 1865 |
The Malabar snakehead [C. diplogramma], is one of the most enigmatic and least known of all channids. Sir Francis Day [1] described Ophiocephalus diplogramma in 1865 based on one juvenile specimen (42 mm in length) collected near the mouth of the Cochin River in the port city of Cochin (Southwestern India), and called it Malabar snakehead. The color pattern of this juvenile matched with that of juveniles of another species of snakehead, O. micropeltes originally described by Cuvier and Valenciennes [2] from Java, Indonesia. This possibly led Francis Day to synonymise C. diplogramma with C. micropeltes in 1878 [3]. The close similarity, rarity of adult specimens in museum collections, and the fact that no taxonomist has studied this snakehead since its description, resulted in the acceptance of the synonymy by subsequent taxonomists. In 2011 the C. diplogramma, has been shown to be a valid species 134 years after it was synonymised [4], making it a valid endemic species of peninsular India.
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Channa diplogramma shows multiple color phases during its life history, which makes local fishers, believe that they are different species. The different specimens are also known by different vernacular names (Pulivaka, Karivaka, Manalvaka, and Charalvaka). All these specimen in different color phases occur sympatrically and utilize the same ecological habitat.
Channa diplogramma is endemic to the southern Western Ghats of peninsular India. It is known from the Rivers (including its principal reservoirs) Meenachil, Manimala, Pampa, Achenkovil and Kallada in Kerala state, as well as the Chittar and Tambraparini Rivers (and its reservoirs) in Tamil Nadu state in India.
Channa diplogramma differs from all other species in the genus by its high number of lateral line scales (103–105 vs. 36–91). It further differs from all other Channa species, except C. bankanensis, C. lucius, C. micropeltes and C. pleurophthalma by the presence of gular scales, a patch of scales between the anterior tips of the lower jaws, visible in ventral view. Channa diplogramma differs from C. bankanensis, C. lucius, and C. pleurophtalma by having a very different color pattern. C. diplogramma differs from its sister species C. micropeltes by a combination of characters viz., number of caudal fin rays, lateral line scales, scales below lateral line; total vertebrae, pre-anal length and body depth.
Channa diplogramma is listed as a 'Vulnerable' species in the IUCN Red List of Threatened Species in view of its restricted distribution and threats including fishing, habitat loss and pollution.