Ultrastructural and molecular studies of Microgemma carolinus n. sp. (Microsporidia), a parasite of the fish Trachinotus carolinus (Carangidae) in Southern Brazil

Abstract

A new species of Microsporidia Microgemma carolinus n. sp. found in the marine teleost Trachinotus carolinus collected in Florianópolis, Brazil was described based on light, ultrastructural and phylogenetic studies. This parasite developed in the liver forming whitish xenomas that contained different developmental stages with monokaryotic nuclei. The periphery of the xenoma presented some vacuolization and possessed several small projections in the membrane. The mature spores, measuring 3·8 ± 0·4 μm in length and 2·4 ± 0·4 μm in width, were slightly pyriform to ellipsoidal and had rounded ends. The polaroplast was bipartite and the isofilar polar filament was coiled with 8 - 9 turns in a single or double row at the posterior end of the spore. The nucleus was voluminous and in a central position, measuring ~0·9 μm in diameter. A large posterior vacuole appeared as a pale area, occupying about a third of the spore length. The SSU rRNA gene was sequenced and analysed using maximum parsimony, maximum likelihood and neighbour-joining methods. This study allowed us to conclude that this was a new species of the genus Microgemma, being the first description of this genus from among South America fauna.

Ultrastructure and phylogeny of the parasite Henneguya carolina sp. nov. (Myxozoa), from the marine fish Trachinotus carolinus in Brazil

“…This species is appreciated both as a game and food fish, presenting high commercial value for the aquaculture industry (Riley et al 2009). Nevertheless, few parasitological surveys have been conducted on the Florida pompano inhabiting the Brazil-ian coast, and to date we know of only 1 report of microsporidian infection (Casal et al 2012).…”

Hepatic microsporidiosis of mudskipper, Boleophthalmus dussumieri Valenciennes, 1837 (Perciformes: Gobiidae), due to Microgemma sp.

“…The sequence of the present species of Microgemma (1269 bp) showed high genetic similarity (~ 98.9-99.8%) and less genetic divergence value with M. tilanpasiri (0.2%), M. carolinus (0.7%), and M. vivaresi (1.1%). Several previous studies have also reported low divergence values between M. carolinus and M. tilanpasiri (0.7%), M. tincae and M. vivaresi (0.7%), and M. caulleryi and Tetramicra brevi lum (0.3%) (Freeman et al 2015;Casal et al 2012). This could be due to the recent evolution of the species and subsequently less divergence time from their most recent common ancestor.…”

“…Lom and Nilsen (2003) stated that the level of genetic variation between closely related species of microsporidians varies as per the host group. Several reports showed a lack of su cient genetic variation among closely related species of microsporidia that infect shes (Nilsen et al 1998;Cheney et al 2000;Casal et al 2012;Freeman et al 2015). The sequence of the present species of Microgemma (1269 bp) showed high genetic similarity (~ 98.9-99.8%) and less genetic divergence value with M. tilanpasiri (0.2%), M. carolinus (0.7%), and M. vivaresi (1.1%).…”