Irengbam Linthoingambi’s scientific contributions

A new species of the genus Garra is described from the Chalou River in Manipur, northeastern India. The new species, Garra chingaiensis, belongs to the "proboscis with a transverse lobe species group". It further belongs to the unilobed proboscis group and can be distinguished from its congeners in having a combination of the following characters: a prominent 3-4 unicuspid tubercles on the unilobed proboscis, a transverse lobe with an irregular 11-13 unicuspid tubercles, lateral surface of the snout with 2-3 minute tubercles; a narrow black 5 stripes, laterally more distinct towards caudal peduncle, 3 stripes below the lateral line and 2 stripes above lateral line; black stripes in the middle of caudal fin; chest and belly scaled; 12 circumpeduncular scales; 34-35 lateral scales; 8 ½ branched dorsal fin rays; and 5 ½ branched anal fin rays.

The present work is a result of a Preliminary survey on the fish diversity of two major rivers of Arunachal Pradesh i.e Siang river and Lohit river at Pasighat and Tezu. A total of 24 species belonging to 5 families of Cyprinidae, Siluridae, Sisoridae, Belonidae and Bagridae were collected. Among them, Barilius, Garra, Tariqilabeo, Glyptothorax were commonly found in both the rivers. While in Lohit River of Tezu a greater number of species of the genera Raiamas, Xenentodon, Pterocryptis, Pseudocheneis, Schizothorax, Batasio, Puntius, Wallago were collected. A new species of garra is also reported belonging to "Smooth snout group", having prominent, regular scales on abdomen, moderately large gular disc, broader than long (length 37.4% HL,55.3 width % HL), anus posteriorly positioned, a black spot at upper angle of gill opening.

Garra lungongza sp. nov., is described from the Dei-thung Shumang River, Nagaland. It belongs to the member of "smooth snout" group. It differs from its congeners in having the following characteristics: head strongly depressed; snout tip with 23-34 rounded hollow pits; Gular disc elliptical; torus crescentic; labellum covered by lateral distal margin of rostral cap; pre-dorsal scales irregularly arranged with 12-14 scale rows; lateral line with 37+ 2(1)-3(5) scales.

Scanning electron microscopy (SEM) on the associated structures of mouth of Psilorhynchus ngathanu and Garra abhoyai has been carried out. SEM structures of mouth parts of P. ngathanu reveal the presence of elongate and pointed tubercles on the rostral cap. Papillae studded with unculi and taste buds are seen along with numerous mucus. In G. abhoyai hexagonal epithelial cells with elevated cell boundaries and scantly mucous gland opening are observed. Taste buds present at the apex of epithelial cells with micro-ridges pattern have also been observed. Histology of rostral cap and parts of Gular disc of Garra abhoyai are also carried out. Fringed and papillated rostral cap on upper lip are observed. Clavate cell, sensory cell, pigment cell of central callous are seen.