Omanicotyle heterospina n. gen. et n. comb. (Monogenea: Microcotylidae) from the gills of Argyrops spinifer (Forsskål) (Teleostei: Sparidae) from the Sea of Oman

A Monogenean Gill Parasite within the Genus Haliotrema (Ancyrocephalidae) Infecting Argyrops filamentosus Fish: Morphology and Molecular Studies

Due to the presence of different parasite taxa and other disease-causing agents, all fish species are extremely prone to dangers. As a result, the current study focused on some of the monogenean parasites that infect one of the economically important fish species, the soldier bream Argyrops filamentosus, from the Red Sea coast of Jeddah, Saudi Arabia. Following that, thirty A. filamentosus fish specimens were examined for monogenean parasites. The parasitic species were isolated and morphologically and molecularly studied. The presence of one monogenean species of Haliotrema susanae (F: Ancyrocephalidae) infecting gills was observed in 50% of the investigated fish species. The ancyrocephalid species Haliotrema susanae is characterized by having all generic features within the genus Haliotrema. It could be distinguished from other species within this genus by the male copulatory organ including a copulatory tube with no accessory piece and a haptor made up of two pairs of anchors, two bars, and seven pairs of marginal hooks. As ectoparasitic taxa of the investigated sparid fish, the current study of Haliotrema species constitutes the first report of this genus. A molecular phylogenetic analysis based on the partial 28S rRNA gene region was analyzed to investigate the phylogenetic affinity of this parasite with the genus Haliotrema belonging to Ancyrocephalidae. This study considers the addition of a new genetic sequence for this parasite species.

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.

Heteromicrocotyla polyorchis Unnithan, 1961 (Monogenea: Heteromicrocotylidae), a gill parasite of the yellow-spotted trevally, Carangoides fulvoguttatus (Carangidae) from Saudi Arabia: Morphology and phylogeny

Little information for parasitic infections of Carangoides fulvoguttatus was recorded. The present study was intended to investigate the gill parasite Heteromicrocotyla polyorchis of this fish and to provide a full morphological description and clarify its taxonomic status through phylogenetic analysis of the 28S rRNA gene region. A total of sixty fish specimens have been collected from the studied area (the Red Sea in Jeddah Province, Saudi Arabia) and gills were isolated and examined for identification of parasites. Using light electron microscopy, the recovered monogenean parasite's morphology was exhaustively characterized and described. Microscope examinations found that this parasite species represent Heteromicrocotyla polyorchis, and it could be distinguished from congeners of the same genus by armed genital atrium and cirrus sac, follicular post-ovarian testes, unique shape and number of clamps on both haptor sides, and the dorsally curved tip of the male copulatory organ. Morphological features were combined with molecular analysis of the 28S rRNA gene region. The selected gene for the isolated Heteromicrocotyla species was analyzed using appropriate primers to assist in phylogeny with those in the GenBank database. The present monogenean species was characterized by unique genetic sequences that were analyzed and deposited in the GenBank for the first time under the accession number MW406473. Phylogenetic analyses reported that the maximum identity between the current Heteromicrocotyla species and taxa of Heteromicrocotylidae was between 91.42 and 92.09% and confirmed its taxonomic status in this family with a well-distinct clade. The present study supported the second report of H. polyorchis as carangid fish ectoparasites and investigates the first appearance in C. fulvoguttatus inhabiting Saudi Arabia.

A sucker for the job: morphology and functioning of suckers of polystomatid monogeneans

Monogeneans rely on firm attachment to often flexible and uneven surfaces and are renowned for their effective posterior attachment structures in the form of adhesives, clamps, hamuli and suckers. Polystomatids do not secrete adhesives and do not have clamps. While only some have hamuli, all have suckers in the adult form. Three different types of haptoral suckers have been described based on basic morphology but have never been studied in depth. Using enzyme digestion and light (differential interference contrast), confocal and scanning electron microscopy, we examined representatives and propose four sucker types. Haptoral sucker Type I are symmetrical soft, flexible, cup- to disk-shaped suckers and are found in all polystomes infecting frogs and salamanders. Type II suckers are symmetrical soft, flexible, cup-shaped suckers with a hollow continuous skeletal ring and no other skeletal elements. They are found in species of Nanopolystoma Du Preez, Wilkinson et Huyse, 2008 infecting caecilians. Type III suckers are symmetrical firm, cup-shaped suckers with elaborate skeletal elements that contribute to a secure grip on the host tissue. This type of sucker is found in all polystomes infecting freshwater turtles and the common hippopotamus. Type IV suckers are asymmetrical with an elaborate series of long, thin sclerites with terminal spines or hooks. This type of sucker is only known from Concinnocotyla australensis (Reichenbach-Klinke, 1966) infecting the Australian lungfish. These different sucker types are crucial for the survival of polystomatid flatworms within their respective microhabitats.

Paracaesicola nanshaensis n. gen., n. sp. (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.

Microcotyle visa n. sp. (Monogenea: Microcotylidae), a gill parasite of Pagrus caeruleostictus (Valenciennes) (Teleostei: Sparidae) off the Algerian coast, Western Mediterranean

Parasite biodiversity of fish of the southern part of the Mediterranean sea is still incompletely explored. We describe here Microcotyle visa n. sp. from the gill filaments of the bluespotted seabream Pagrus caeruleostictus (Valenciennes) (Sparidae) collected off the Algerian coast. The identity of fish hosts was confirmed by barcoding. Microcotyle visa n. sp. is herein described and illustrated. Analysis of the cox1 gene of the monogeneans revealed minor intraspecific variation (1.4%), an order of magnitude lower than the distance between this species and other Microcotyle species (10-15 %). Microcotyle visa n. sp. is distinguished from Microcotyle erythrini van Beneden & Hesse, 1863, a congener infesting sparids, on the basis of morphological (size of clamps, number of testes) and molecular (cox1) differences. This is the fourth member of the genus known to parasitise a sparid host. A species of Paramicrocotyle sp. included in the molecular analysis was nested within a robust Microcotyle + Paramicrocotyle clade; in the absence of demonstrated molecular and morphological differences, we consider that Paramicrocotyle Caballero & Bravo-Hollis, 1972 is a junior synonym of Microcotyle van Beneden & Hesse, 1863 and transfer two species of Paramicrocotyle as Microcotyle danielcarrioni (Martinez & Barrantes, 1977) n. comb. and Microcotyle moyanoi (Villalba & Fernandes, 1986) n. comb.

Three-dimensional morphology of rigid structures as a tool for taxonomic studies of Dactylogyridae (Monogenea)

Dactylogyridae is overwhelmingly the most abundant and diverse taxon among monogeneans in continental waters of South America. Their small body size requires considerable sampling effort and training for collecting and identifying the worms from the gills, skin, nasal cavities, and other microhabitats. Indeed, diagnostic characteristics as sclerites and male copulatory complex are generally less than 100-μm long and are essential for taxonomic description and identification of species. Here, a combination of simple and routine methods for three-dimensional morphological studies on hard structures is proposed for dactylogirids: SDS treatment for clarification of specimens and enzymatic digestion with proteinase K for freeing sclerotized structures, followed by laser confocal microscopy. This method is applicable to fresh or fixed specimens and does not require staining or dehydration. Indeed, stable autofluorescence emission is detectable at 500-530 nm for bars, anchors, and male copulatory complex when excited by argon laser. Advantages of this protocol over previous methodologies for taking laser confocal images are discussed. Open access software for image processing was used for three-dimensional reconstruction of sclerotized structures generating models and full 360° rotation videos.