Hepatic Microsporidiosis of Mudskipper, Boleophthalmus Dussumieri Valenciennes, 1837 (Perciformes: Gobiidae), due to Microgemma Sp.

Abstract

The present study reports a case of hepatic microsporidiosis caused by Microgemma sp in brackishwater sh, Boleophthalmus dussumieri (Valenciennes, 1837) (n = 60), from north-west coast of India. An eightmonth study from September 2017 to April 2018 revealed a prevalence of 11.6% for this parasite. The microsporidian showed tissue-specic infection and did not reveal any gross pathology in infected sh. Large whitish cysts containing microspores of size 0.3–0.5 mm were observed in the liver of sh. The range of pyriform microsporidian spore size varied from 2.9–3.77 X 1.85–2.67 µm. Histological observations of infected liver revealed large xenoma of the microsporidian lled with spores and encircled by a cyst wall-like layer. Scanning electron microscopy of the spores showed a distinct groove on the anterior end of the spore for polar tube extrusion. Polymerase chain reaction (PCR) amplication of the DNA extracted from the microsporidian spores using primers targeting small ribosomal subunit DNA (SSU rDNA) yielded ~ 1340 bp amplicon and the genetic distance analysis showed a 0.2% variation with the reported M. tilanpasiri. Accordingly, in the phylogenetic tree, the present species of Microgemma clustered with M. tilanpasiri. Even though, the morphomeristic characters of the present Microgemma sp. was marginally different from the reported M. tilanpsasiri; the SSU rDNA showed considerably higher similarity with M. tilanpasiri. Thus, we report the species of Microgemma as Microgemma aff. tilanpasiri from a new host. This is the rst report of a microsporidian from B. dussumieri and the rst record of the genus Microgemma from India.