Light and scanning electron microscopic studies on eustrongylides exciscus larvae (Nematoda: Dioctophmida) from Channa punctatus bloch from India

Abstract

Fourth stage larvae of Eustrongylides exciscus were recovered from the abdominal cavity, musculature and ovaries of Channa punctatus (prevalence 24%, intensity 2 to 18 per fish). Light and Scanning Electron Microscopy (SEM) were conducted to demonstrate the surface anatomy of the worm. The worm is slender, elongated and cylindrical. The mouth is slit-like, surrounded by two lateral rows of somatic papillae, cephalic end was conical with 12 labial papillae arranged in two circles of 6 papillae each. Scanning electron microscopy on attachment structures revealed that the inner papillae had narrow bases and spine-like apices, the outer ones had wide bases and nipple like apices encircled by a conspicuous ring and embedded in the body wall. The body of the worm was striated and grooved assisting flexibility to the worm during movement. Attempts to develop the larvae in ducks Anas platyrynchas by feeding were unsuccessful up to 17 days post infection suggesting that ducks were not the final hosts of the worm. Channa punctatus serves as a paratenic host for Eustrongylides.