Morphological and molecular description of a new species of Myxobolus (Myxosporea: Myxobolidae) infecting Planiliza macrolepis (Smith, 1846) from India

The description of Myxobolus meijiangensis n. sp. (Myxozoa: Myxobolidae) and its pathogenicity to the gills of goldfish

Myxobolus Bütschli, 1882 is the most speciose myxozoan genus, although some species have only been described according to the morphological characteristics of spores. In the present study, a new Myxobolus species infecting the gill lamellae of goldfish from Chongqing, China, was described using a comprehensive analysis of morphological, molecular, and histological data. Mature spores were flat-pear in valvular view with tapering anterior and rounded posterior ends, measuring 11.0 ± 0.4 (10.4-11.6) μm in length and 10.3 ± 0.3 (9.6-11.0) μm in width. Two equal-sized elongate pyriform polar capsules were 5.6 ± 0.6 (4.5-6.4) μm long and 3.5 ± 0.5 (2.4-4.1) μm wide. Polar tubules were coiled with 8 or 9 turns. The small-subunit ribosomal DNA gene sequence length of the present species was 1951 nt, and the highest similarity was 97.99% with M. pyramidis. Comparative analysis of the morphological and molecular data revealed that the present species was distinct from other known myxosporeans. Plasmodia were located at the interlamellar troughs nearing the top of the primary gills. Infection by the present species destroyed the original structure of gill lamellae and caused an inflammatory response, eventually leading to fish dyspnea. The morphological, molecular, and pathological data from the present study can be used for aquaculture since they provide guidance for easy detection and future control of this myxosporidiosis.

An update of the species of Myxosporea (Cnidaria, Myxozoa) described from Indian fish

A synopsis of Myxosporea (Cnidaria, Myxozoa) species described in about the last 14 years in Indian fish is provided. The synopsis include a total of 97 new species, and 18 species redescribed including significant new data, namely molecular characterization, distributed by 19 genera. For each species are indicated, in tabulated format, the morphological characteristics and the Gen Bank Accession Number whenever possible. Data about the type host and type locality are included also, and a complete list of references is provided. The information presented, combined with former synopsis, allow an update general view about these parasites infecting Indian fish hosts.

Morphological and Molecular Characterization of Myxobolus planilizae n. sp. (Cnidaria; Myxosporea; Myxobolidae) Infecting the Largescale Mullet Planiliza macrolepis (Smith, 1846) Collected From Cochin Backwaters, India

PURPOSE

Myxobolus planilizae n. sp. is described from the intestinal muscles of the largescale mullet Planiliza macrolepis from Cochin backwaters, Kerala, India.

METHODS

Host fishes inhabiting Cochin backwaters were collected using Chinese nets/gill nets. The morphometry and morphological studies were carried out using Nomarski differential interference contrast (DIC) optics, followed by molecular and phylogenetic analyses of the small subunit ribosomal DNA gene (SSU rDNA).

RESULTS

Plasmodia small, pale white, and infect the muscles of the intestine; measured 0.13-0.22 (0.17) × 0.09-0.14 (0.13) mm. Mature myxospores pyriform in valvular view, and biconvex in sutural and apical views with a short anterior extension, and measured 7.45-8.75 (8.40) × 6.04-6.86 (6.25) µm. Shell valves with sutural ornamentations. Polar capsules two, equal, pyriform, measured 3.96-4.54 (4.45) × 2.22-2.94 (2.52) µm. Polar filament arranged in five coils, measured 24.41-34.44 (28.52) µm when extruded. In morphological and morphometric analysis, the present species exhibit remarkable variations from other species of the genus Myxobolus. In molecular analysis, the present species revealed the highest identity of 91.85% and divergence of 9.95% with related species, underlining its molecular uniqueness. In phylogenetic analysis, species of Myxobolus infecting mullets appeared as a separate clade and the present species was positioned distinctly with a high bootstrap value.

CONCLUSIONS

Based on morphology, morphometry, and molecular and phylogenetic analyses, along with tissue/host specificities and geographic location, the present parasite is treated as new and is reported here as M. planilizae n. sp.