Six species of nonmazocraeid monogeneans including two new species from clupeiform fishes of Visakhapatnam coast, Bay of Bengal

During a survey on monogenean parasites of clupeiform fishes of Visakhapatnam coast, Bay of Bengal, apart from typical mazocraeids, 6 species of nonmazocraeids, including two new species were encountered. These belonged to 5 genera distributed over 4 families: Family Gastrocotylidae: Engraulicola thrissocles from Thryssa mystax, T. setirostris, T. malabarica; Engraulicola longisomum n.sp. from Thryssa mystax, T. setirostris, T. malabarica; Pellonicola elongatus from Ilisha filigera; family Megamicrocotylidae: Megamicrocotyle chirocentrus from Chirocentrus dorab; family Microcotylidae: Microcotyle clupei n.sp. from Thryssa mystax and T. setirostris; family Diclidophoridae: Keralina opisthopterus from Opisthopterus tardoore. Engraulicola longisomum n. sp. differs from E. thrissocles in the larger body size, in the relatively smaller size of haptor and also in the number of clamps and alignment of reproductive organs. Microcotyle clupei n.sp. the first species of the genus to be reported from clupeiform fishes differs from other species of the genus, mainly in the presence of a circlet of spines on the oral sucker. Descriptions are provided for all the species collected. Megamicrocotyle johnstoni is synonymized with M. chirocentrus.

(Monogenea: Microcotylidae) from the Gills of the Cardinal Fish Apogon imberbis (Teleostei: Apogonidae) off the Algerian Coast of the Western Mediterranean

PURPOSE

A new monogenean Microcotyle justinei n. sp. (Monogenea: Microcotylidae) is described based on specimens found on the gill filaments of the cardinal fish Apogon imberbis (Apogonidae) off the Algerian coast of the Western Mediterranean.

METHODS

Monogeneans were examined, measured and drawn for a comparative morphological study with other species of Microcotyle and characterised molecularly using a partial fragment of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. The identification of fish was confirmed by molecular barcoding using the cox1 gene.

RESULTS

The new species is distinguished from all other species of the genus by a combination of features, such as the number and size of the clamps, the shape and size of the genital atrium and the number of testes. The molecular analysis of the cox1 gene sequences showed that interspecific differences between Microcotyle justinei n. sp. and published sequences of Microcotyle spp. was greater than 8.8%, strongly suggesting that the new species is distinct from other congeners with sequences available on GenBank.

CONCLUSION

The morphological and molecular analyses support the status of M. justinei as a new species. The present finding extends the list of Microcotyle spp. to 72.

australiensis (Microcotylidae)

This study determines the occurrence and molecular characterisation of Monogenea from three commercially important Australian fish: Australian sardine Sardinops sagax (Jenyns), Australian anchovy Engraulis australis (White), and eastern school whiting Sillago flindersi McKay. Earlier studies have provided only morphological species identification, whereas this study combines both morphological and molecular methods. A total of 247 fish across 3 species, sourced from the New South Wales and Victorian coasts, were examined for Monogenea. A total of 187 monogenean parasites were recovered from the gills. The overall prevalence, mean intensity, and mean abundance were 34%, 2.23, and 0.78, respectively. The parasites were initially classified morphologically as three species across two families. Family Mazocraeidae was represented by Mazocraes australis Timi et al. J Parasitol 85:28-32, 1999, and family Microcotylidae by Polylabris sillaginae (Woolcock, Parasitology 28:79-91, 1936) Dillon, Hargis, and Harrises, 1983 and P. australiensis Hayward, 1996. Molecular identification of parasites was conducted through sequencing of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. The fish hosts in the present study were also barcoded (mitochondrial cox1 gene) to confirm specific identities. There was no comparable cox1 sequence available in GenBank for the parasites found in the present study. However, the phylogenetic tree clustered the monogenean species identified in this study according to their familial groups of Mazocraeidae and Microcotylidae. The presence of M. australis on E. australis and S. sagax was confirmed in this study. Polylabris australiensis was only found on S. sagax but Si. flindersi was found to be a host for both Polylabris species. This study is the first to explore the mitochondrial cox1 genes of these three-monogenean species. These findings will serve as a foundation for future monogenean research in Australian waters and elsewhere.

Occurrence and molecular identification of Monogenea from blue-spotted flathead Platycephalus caeruleopunctatus (Scorpaeniformes: Platycephalidae) in Australian waters

This study describes the occurrence and molecular identification of Monogenea from blue-spotted flathead Platycephalus caeruleopunctatus (McCulloch) (Scorpaeniformes: Platycephalidae) from waters off the NSW coast, Australia. Platycephalus spp. are favoured by consumers for delicate, white, mild flavoured flesh and therefore are commercially important species within Australia. Platycephalus spp. are also extensively targeted by Australian recreational fishers. There has been no previous study that has exclusively focused on Pl. caeruleopunctatus in Australia or globally. Although a single study by Dillon (1985), of monogeneans infecting Platycephalus spp. from Australian waters, identified Microcotyle bassensis Murray, 1931 in Pl. caeruleopunctatus. The present study combines both morphological and molecular methods to identify both host and parasites. A total of 116 fish, sourced from the waters off the coast of New South Wales, Australia, were examined. A total of 1498 Monogenea were recovered from the gills. The overall prevalence, mean intensity, and mean abundance were 72%, 18.05, and 12.91, respectively. Monogenea were initially classified morphologically as two different species M. bassensis (family: Microcotylidae) and Platycephalotrema bassense (Hughes, 1928) Kritsky & Nitta, 2019 (family: Ancyrocephalidae). Molecular identification of Monogenea was conducted through sequencing of their mitochondrial cytochrome c oxidase subunit 1 (cox1) and nuclear 28S genes. The specific identification of host Pl. caeruleopunctatus was confirmed through sequencing the cox1 gene. There was no comparable sequence for cox1 and 28S genes available in GenBank for the monogenean species found in the present study. Only a single sequence (obtained from the nuclear ITS2-rDNA) was deposited in GenBank for M. bassensis. However, the phylogenetic analyses of mitochondrial and nuclear sequences revealed that the identified Monogenea clustered according to their familial groups. Platycephalotrema bassense was identified for the first time in Pl. caeruleopunctatus in the present study. This study has provided the first evidence for the exploration of both cox1 and 28S sequences of all Monogenea. The findings of this study serve as a foundation for future monogenean research on other Platycephalus spp. from Australian waters.

Novel molecular data for monogenean parasites of sparid fishes in the Mediterranean and a molecular phylogeny of the Microcotylidae Taschenberg, 1879

During a study of the monogeneans of four sparid fishes (Diplodus vulgaris, Pagellus bogaraveo, Pagrus pagrus and Sparus aurata) from the Western Mediterranean off Algeria, a large collection of parasites was characterised molecularly (28S rRNA and cox1 genes). A total of 46 partial sequences (23 for each gene) were generated from 38 isolates of monogeneans which included four species (Atrispinum acarne, Microcotyle erythrini (sensu stricto), Sparicotyle chrysophrii and Prostatomicrocotylinae gen. sp.) of the family Microcotylidae, two putative species of the family Capsalidae (Encotyllabe spp.), and one species (Choricotyle chrysophryi) of the family Diclidophoridae. Our study provides (i) the first molecular data for the Capsalidae in the Mediterranean; (ii) the first record of a member of the Prostatomicrocotylinae in the Mediterranean and in a sparid fish (D. vulgaris); (iii) the first cox1 sequences for A. acarne; (iv) the second record of M. erythrini (s.s.) from P. pagrus; and (v) the second confirmed by molecular data record of S. chrysophrii in wild populations of S. aurata. The first phylogenetic hypotheses for the family Microcotylidae developed here, revealed the monophyly of the subfamily Prostatomicrocotylinae and the genus Microcotyle but the relationships among the subfamilies were still largely unresolved with the best represented subfamily Microcotylinae being polyphyletic. Our results highlight the importance of molecular methods in the assessment of monogenean diversity and the need for a thorough taxon-sampling approach to increase the accuracy of phylogenetic reconstruction of the relationships of the large and taxonomically complex polyopisthocotylean family Microcotylidae.

Morphology and molecular phylogeny of Pauciconfibuloides amazonica gen. n. sp. n. (Platyhelminthes, Monogenoidea) parasitizing the Amazonian croaker Plagioscion squamosissimus

An integrative study was performed to understand the phylogenetic relationships of an undescribed, freshwater species of microcotylid parasitizing Plagioscion squamosissimus from the Amazon River Basin. Based on morphological and molecular analysis (18S rDNA and partial 28S rDNA genes), a new genus is proposed to accommodate this new species, Pauciconfibuloides amazonica gen. n. sp. n. The new genus is closely related to Protastomicrocotylinae and Pauciconfibula by sharing the vagina, male copulatory organ, and genital atrium all unarmed. However, Pauciconfibuloides gen. n. can be distinguished from those taxa by the prostatic system and position of the vaginal pore. Molecular phylogenetic inference suggests a sister relationship with species of Polylabris (Prostatomicrocotylinae), but to date, there are no available 18S or 28S rDNA sequences of Pauciconfibula to be compared. This is the first report of a microcotylid parasitizing a freshwater sciaenid from South America.

(Monogenea, Microcotylidae) a gill parasite of Paracaesio sordida (Teleostei, Lutjanidae) from the South China Sea

Paracaesicola n. gen., is erected herein to accommodate a new microcotylid species, Paracaesicola nanshaensis n. sp., collected from the Yongshu Reef, South China Sea. This species is the first monogenean to be recorded from the gills of Paracaesio sordida. The new species is characterized by the following features: (i) haptor short, with clamps arranged in two equal bilateral rows; (ii) testes numerous, arranged in two roughly alternating longitudinal rows, extending into the haptor; (iii) genital atrium armed with 16 robust spines, which are vertically arranged on top of the sausage shaped muscular male copulatory organ; and (iv) single vagina, bottle-shaped, with a distinctly bulbous vaginal atrium. The terminals of the reproductive system discriminate Paracaesicola n. gen. from all other genera in the Microcotylidae. Molecular phylogenetic analyses, based on partial 28S rDNA, places Paracaesicola nanshaensis n. sp. within the microcotylid clade, but its sequence differs from all known available microcotylid sequences.

Bivagina Pagrosomi Murray (1931) (Monogenea: Polyopisthocotylea), a Microcotylid Infecting the Gills of the Gilt-head Sea Bream Sparus Aurata (Sparidae) from the Red Sea: Morphology and Phylogeny

Introduction

Monogenea is a class of ectoparasitic flatworms on the skin, gills, or fins of fish. Microcotylidae is a family of polyopisthocotylean monogeneans parasitising only marine fishes. This work describes and taxonomically determines a microcotylid polyopisthocotylean monogenean in an important fish in Saudi aquaculture.

Material and Methods

Thirty gilt-head sea bream captured alive from the Red Sea of Saudi Arabia were examined for monogenean infection. Worms were described morphologically and morphometrically by light microscopy and multiple sequence alignments and phylogenetic trees were also constructed after maximum likelihood analysis of the 28S rRNA sequences.

Results

Seventeen fish were infected by a monogenean parasite in the gill lamellae. It showed a bilobed anterior extremity, two rows of numerous unequal clamps of microcotylid type, and paired muscular vaginae crowned by differently sized spines. The vaginal number and its relative armature suggested the species’ affiliation to group D; the parasite possessed large, muscular vaginae with a full corona of spines over almost the entire width resembling Bivagina pagrosomi Murray (1931). The molecular analysis of the parasite 28s rRNA revealed 97% homology with B. pagrosomi (AJ577461.1).

Conclusion

The results confirmed the taxonomic status of the parasite recorded. On the basis of morphology and molecular data, we consider that several conclusions on the systematic status of microcotylids from Red Sea fishes in Saudi Arabia should be discussed.