Myxobolus goensis N.sp (Myxozoa, Myxosporea, Myxobolidae), a parasite of the gills of Mugil cephalus (Osteichthyes, Mugilidae) from Goa, India

Abstract

Two species of Myxobolus are reported from the gills of Mugil cephalus collected at Goa, India: M. goensis n.sp. and M. parvus Shulman, 1962. Myxobolus goensis n.sp. forms digiiiform or founded plasmodia between the gill rakers. Their spores are oval in frontal view, with tapered anterior extremity, and lemon-shaped in lateral view, measuring 9.7 (9.5-10.5) mu m in length, 66 (6-7.5) mu m in width, and 5.2 (5-6) mum in thickness. The polar capsules are pyriform end unequal in size. The larger ones are 5.3 (4.5-6) mu m long and 2.4 (2-3) mum wide; the smaller ones are 2.4 (2-3) mu m long and 1.8 (1.5-2) mum wide. The polar filament forms five turns aligned perpendicularly to the longitudinal axis air the larger polar capsules. Within the smaller polar capsules The polor filament is difficult to observe and, apparently, forms three coils. The spores are distinctly different from other Myxobolus species infecting M. cephalus and other Mugil spp. Furthermore, the present material is also different from 204 Myxobolus species presenting differently sized polar capsules, representing nearly all the known species with this characteristic. The fact that only the M. cephalus specimens were infected among a sample of 206 fish specimens, comprising 27 different species, strongly suggests that this parasite is specific to M. cephalus.