Zschokkella epinepheli n. sp. (Myxosporea: Myxidiidae) infecting the gallbladder of the white grouper Epinephelus aeneus (Serranidae) from Tunisian waters

A new coelozoic myxosporean species, Zschokkella epinepheli n. sp., collected from the gallbladder of the white grouper Epinephelus aeneus (Perciformes: Serranidae) from the bay of Bizerte, Tunisia, is described based on morphological and molecular characteristics. Myxospores and plasmodia were observed floating free in the bile. Mature plasmodia were polysporic and subspherical in shape, measuring 85.0–94.0 μm long and 70.0–82.0 μm wide. Mature myxospores were ovoid in valvular view, measuring 10.0 ± 1.7 (8.0–11.0) μm in length and 7.0 ± 0.3 (6.6–7.5) μm in width. Polar capsules were pyriform and equal in size, measuring 3.0 ± 0.2 (2.8–3.6) μm in length and 2.3 ± 0.3 (1.8–2.7) μm in width. Myxospore valves had 12–14 longitudinal striations. Based on the small subunit rDNA, the new species Z. epinepheli n. sp. differs from all other Zschokkella species for which there is a DNA sequence deposited in GenBank. Phylogenetic analysis revealed that Z. epinepheli n. sp. clustered in the marine subclade of Zschokkella species within the biliary tract IV clade. This is the first report of a Zschokkella species from the gallbladder of an epinephelin fishes.