Hepatic M i c r o s p o ri d i o s i s o f M u d s k i p p e r, 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 eight-month study from September 2017 to April 2018 revealed a prevalence of 11.6% for this parasite. Themicrosporidian showed tissue-specic 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. Therange of pyriform microsporidian spore size varied from 2.9–3.77 X 1.85–2.67 µm. Histologicalobservations of infected liver revealed large xenoma of the microsporidian lled with spores andencircled by a cyst wall-like layer. Scanning electron microscopy of the spores showed a distinct grooveon the anterior end of the spore for polar tube extrusion. Polymerase chain reaction (PCR) amplicationof the DNA extracted from the microsporidian spores using primers targeting small ribosomal subunitDNA (SSU rDNA) yielded ~ 1340 bp amplicon and the genetic distance analysis showed a 0.2% variationwith the reported M. tilanpasiri. Accordingly, in the phylogenetic tree, the present species of Microgemmaclustered 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 highersimilarity with M. tilanpasiri. Thus, we report the species of Microgemma as Microgemma aff. tilanpasirifrom a new host. This is the rst report of a microsporidian from B. dussumieri and the rst record of thegenus Microgemma from India.