Myxobolus saladensis, Marcotegui & Martorelli, 2017

Marcotegui, Paula & Martorelli, Sergio, 2017, Myxobolus saladensis sp. nov., a new species of gill parasite of Mugil liza (Osteichthyes, Mugilidae) from Samborombón Bay, Buenos Aires, Argentina, Iheringia, Série Zoologia (e 2017026) 2017, pp. 1-5 : 2-3

Myxobolus saladensis sp. nov.

( Figs 1-7 )

urn:lsid:zoobank.org:act:51F1772D-C806-4B52-9A59-CB70F10D47A5

Diagnosis. Spherical Pmd containing numerous spores located in the gill filaments and rakers. Pyriform fresh spores tapering anteriorly 10.63±0.36 (range 10.05- 11.13) µm long, 9.24±0.50 (range 8.42-9.79) µm wide, and 4.13±0.36 (range 2,65-4,9) µm thick. Two equal-sized pyriform PC measuring 3.84±0.27 (range 3.33-4.03) µm long and 2.30±0.12 (2.14-2.43) µm wide. Polar filament coiled in four or five turns.

Site of infection: spores located in epithelium of gill rakers.

Etymology. The specific epithet refers to the type locality, Salado River.

Type material. One glass slide with semithin sections of the cyst containing spores (Hapantotype) was deposited in the Museo de La Plata collection, number MLP-Pr-095.

Type Locality. Salado River , Samborombón Bay, Buenos Aires, Argentina .

Type Host: Mugil liza .

Prevalence: 12.7%.

Description. Spores typical of Myxobolus Bütschli, 1882 , rounded in valvular view and biconvex in sutural view, shell valves smooth and without projections. Fresh mature spores pyriform in shape ( Fig. 2 ). Mean spore measurements ± standard deviations as follows: 10.63±0.36 (range 10.05-11.13) long, 9.24±0.50 (range 8.42-9.79) wide, and 4.13±0.36 (range 2.65-4.91) thick. Spore wall thin and smooth comprising two symmetrical and equal shell valves adhering together along the prominent longitudinal sutural line ( Figs 3-6 ). Internally, two equal and elongated pyriform polar capsules (PCs), located side by side at the same level, measured 3.84±0.27 (range 3.33-4.03) long, 2.30±0.12 (range 2.14-2.43) wide ( Figs 3-6 ). Intercapsular appendix not observed. Inside the PCs, polar filament coil displayed four or five slightly oblique to the longitudinal axis ( Fig. 6 ). Apical end of the PCs contained a circular stopper formed by electron-lucent material ( Fig. 6 ). At the posterior pole of the spore, a binucleated sporoplasm contained numerous light vesicles, numerous sporoplasmosomes ( Figs 4 , 5 ).

Nuclei located at the same level, contained uniform chromatin without evident nucleoli ( Fig. 3 ). A schematic drawing of spore morphology ( Fig. 7 ) shows the arrangements of the different structures and organelles.

Figures

Figs 1-4. Light and transmission electron micrographs of the myxosporean Myxobolus saladensis sp. nov. infecting gills and gills rakers of Mugil liza Valenciennes, 1836: 1, semithin section of a plasmodium; 2, isolated spores observed in differential interference-contrast (DIC); 3, ultrathin section of a plasmodium showing several spores at different levels (S); 4, sectioned spore showing the shell valves (V); polar capsules (PC); Sporoplasm (SP) and transverse section of the polar filament (arrows).

Figs 5, 6. Myxobolus saladensis sp. nov. parasite of Mugil liza Valenciennes, 1836: 5, sectioned spore showing valves (V) and their suture lines (arrows), polar capsules (PC), different sections of the polar filaments (arrowheads) and some sporoplasmosomes (Sps); 6, detail of apical region of the PCs showing the PC wall (arrows) composed of two layers and the apical stopper (double arrows) and the different sections of the polar filament (arrowheads).

Fig. 7. Schematic drawing of the morphology of a spore of Myxobolus saladensis sp. nov. witch infects Mugil liza Valenciennes, 1836 from Argentina.