Peripheral Loculi Research Articles

The ultrastructure of nymphal dermal pores and the genitalia of adult male of Phenacoccus solenopsis (Hemiptera: Pseudococcidae)

The cotton mealybug, Phenacoccus solenopsis, has established itself as an invasive insect pest worldwide. It causes structural and physiological damage to various crops and can cause substantial financial losses in their production. The successful reproduction of this pest under a wide range of conditions is a key to its success. Despite this, the morphology of its genitalia, genital sensilla, and wax-producing dermal pores has received little attention, with little descriptions of their ultrastructure. By investigating those features with SEM, the present study revealed considerable new insights into the identification of the nymphal and adult stages of P. solenopsis. In addition, the description of the ultrastructural genital morphology of the immature stages of P. solenopsis has revealed characteristics that facilitate their discrimination. Trilocular pores were observed on both sides of the body, while the quinquelocular pores were distributed only on the ventral surface in both the first and second nymphal instars. The adult male is characterized by two pairs of waxy caudal filaments surrounded by clusters of 55 to 60 stellate pores, and each pregenital segment bears a pair of stellate pores composed of 4 or 5 peripheral loculi. Sensilla trichodea and numerous microtrichia are present on the pregenital segments. The penile sheath bears three subtypes of sensilla basiconica and also campaniformia, whereas the style bears three subtypes of sensilla campaniformia. The findings of this study could assist in the identification of the adult and nymphal stages of P. solenopsis, and also provide insights into the structures found on the genitalia of the adult male that possibly have an important role in mating events and copulatory behavior. Furthermore, these findings were able to contribute to better understanding the functional morphology of P. solenopsis.

Septitrema lichae n. g., n. sp. (Monogenea: Monocotylidae) from the nasal tissues of the deep-sea kitefin shark, Dalatias licha (Bonnaterre) (Squaliformes: Dalatiidae), off Algeria.

Septitrema lichae n. g., n. sp. (Monogenea: Monocotylidae: Merizocotylinae) is described from the nasal tissue of the deep-sea kitefin shark, Dalatias licha (Bonnaterre) (Dalatiidae) collected off Algiers, Algeria. The new genus is distinguished from the other genera in the subfamily by the number and arrangement of the loculi on the haptor having one central and seven peripheral loculi. The diagnosis of the Merizocotylinae is amended to accommodate this species and a key to the genera of the Merizocotylinae is provided. Terminology of the haptoral loculi in the Merizocotylinae and the status of some of the genera in the subfamily are also discussed.

Holocephalocotyle monstrosaen. gen. n. sp. (Monogenea, Monocotylidae) from the olfactory rosette of the rabbit fish,Chimaera monstrosa(Holocephali, Chimaeridae) in deep waters off Algeria

Based on a molecular and morphological study, a new monocotylid genus, Holocephalocotyle n. gen. is proposed to accommodate Holocephalocotyle monstrosae n. sp., found on the olfactory rosette of the rabbit fish, Chimaera monstrosa Linnaeus (Chondrichthyes, Chimaeridae), from the Mediterranean Sea off Algeria. Identification of fish hosts was confirmed by molecular barcoding of the COI gene. A partial 28S rDNA sequence (D1–D2 domain) of Holocephalocotyle monstrosae was obtained; it was distinct from all known monocotylid sequences (p-distance: 15.5–23%). A phylogenetic tree constructed from available monocotylid sequences showed that Holocephalocotyle monstrosae was included, and basal, in a robust group including species of Merizocotyle, Mycteronastes and Empruthotrema, confirming that the species is a member of the Merizocotylinae. The new genus is unique among the Merizocotylinae in having a distinctive pattern of haptoral loculi with one central, five peripheral and seven “interperipheral loculi” partially inserted between peripheral loculi and a compartmentalised sclerotised male copulatory organ. The diagnosis of the Merizocotylinae is amended to include this new genus. The new genus represents the second monocotylid genus recorded from holocephalans.

Electrocotyle whittingtoni n. gen., n. sp. (Monogenea: Monocotylidae: Heterocotylinae) from the gills of a captive onefin electric ray, Narke capensis (Narkidae) at Two Oceans Aquarium, Cape Town, South Africa.

Electrocotyle whittingtoni n. gen., n. sp. (Monogenea: Monocotylidae) is described from the gills of a captive female onefin electric ray, Narke capensis, collected for exhibition at Two Oceans Aquarium in Cape Town, South Africa. Electrocotyle n. gen. is most similar to the heterocotyline genera Heterocotyle and Potamotrygonocotyle but could not be accommodated easily in either of these groups. The new genus is characterised by a haptor with one central and eight peripheral loculi, four unsclerotised structures on the dorsal surface of the haptor, a single unsclerotised non-sinous ridge on the ventral surface of the haptoral septa, large hamuli with a long handle and reduced guard, a vagina with sclerotised walls, and tetrahedral eggs. Molecular phylogenetic analyses based on 28S sequences strongly support the separate genus status of Electrocotyle n. gen and thus support our morphological conclusion. The Heterocotylinae is amended to accommodate the new genus, and the new species is fully described and illustrated herein. This is the first record of a monocotylid from the Narkidae. Electrocotyle whittingtoni n. gen. n. sp. is considered potentially pathogenic given its negative impact on the health of its captive host kept in the quarantine facility at Two Oceans Aquarium.

Triloculotrema euzeti n. sp. (Monogenea, Monocotylidae) from the nasal tissues of the blackspotted smooth-hound Mustelus punctulatus (Carcharhiniformes, Triakidae) from off Tunisia.

Triloculotrema euzeti n. sp. (Monogenea, Monocotylidae, Merizocotylinae) is described from the nasal tissues of the blackspotted smooth-hound Mustelus punctulatus collected from the coastal marine waters off Tunisia. The new parasite species is distinguished from the other two species of the genus, T. japanicae Kearn, 1993 and T. chisholmae Justine, 2009, by the morphology of the sclerotised male copulatory organ which has longitudinal ridges. The species is also characterised by its oötype with short descending and ascending limbs (long and more convoluted in the other two species). The presence of three peripheral loculi, which is the main characteristic of the genus Triloculotrema Kearn, 1993, is unconfirmed. This is the first description of a species of this genus in the Mediterranean Sea and the first record from a coastal shark.

Denarycotyle gardneri n. gen., n. sp. (Monogenea: Monocotylidae: Euzetiinae), from the gills of Rhinoptera steindachneri (Rhinopteridae) from Acapulco, Guerrero, Mexico

Denarycotyle gardneri n. gen., n. sp. (Monogenea: Monocotylidae) is described from the gills of the stingray, Rhinoptera steindachneri (Myliobatidae), collected in marine waters off Acapulco, Guerrero, Mexico. The genus is assigned to Euzetiinae because it has a haptor with one central loculus, one additional loculus on either side of the central loculus and 10 peripheral loculi. However, the genus described herein can be distinguished from Euzetia, the only genus currently assigned to Euzetiinae, by the presence of two accessory structures on the dorsal surface of the haptor and hamuli with a sclerotized accessory piece on each hamulus. Specimens of D. gardneri n. gen., n. sp. were found on the gills of 4 of 18 individuals of R. steindachneri (22%) but were not present on Rhinobatos glaucostigma Jordan and Gilbert (1 individual), Urotrygon rogersi (Jordan and Starks) (2), Narcine entemador Jordan and Starks (3), Aetobatus narinari (Euphrasen) (1) or Dasyatis longa (Garman) (3). This is the third genus and the fourth species of a monogenean recorded from Rhinoptera and the second member of Euzetiinae from Mexico and from the neotropics. Keys to the subfamilies of Monocotylidae and to the species of Euzetiinae, as well as a hypothesis of phylogenetic relationships between Heterocotylinae, Decacotylinae, and Euzetiinae are provided.

Merizocotyle euzeti sp. n. (Monogenea: Monocotylidae) from the nasal tissue of three deep sea skates (Rajidae) in the southwestern Atlantic Ocean.

A new species of Merizocotyle Cerfontaine, 1894 (Monogenea: Monocotylidae) is described from the nasal tissues of three deep sea rajid skates: the southern thorny skate, Amblyraja doellojuradoi (Pozzi), broadnose skate, Bathyraja brachyurops (Fowler), and yellownose skate, Zearaja chilensis (Guichenot), collected off Buenos Aires Province, Argentina, southwest Atlantic Ocean. Two additional species of sympatric rajid, the white-dotted skate, Bathyraja albomaculata (Norman), and the Patagonian skate, Bathyraja macloviana (Norman), were also examined but no merizocotylines were found. The taxonomy of the Merizocotylinae is not widely accepted and, as a result, the status of Thaumatocotyle and Mycteronastes, and their proposed synonymy with Merizocotyle are currently under discussion. The new species differs from its congeners by having a unique haptoral structure, 6 peripheral loculi that are asymmetrically arranged (one much smaller, indistinctly located in the left or right side of the haptor). The presence of the new species in three sympatric species of Rajidae belonging to distinct genera and subfamilies, as well as its absence in sympatric congenerics indicates the lack of phylogenetic host specificity. Host ecology and geographical distribution appear to be more important than host phylogeny in determining the distribution of this parasite across potential hosts in the region. This constitutes the first record of Merizocotyle in the southwestern Atlantic Ocean.

Septesinus gibsoni n. g., n. sp. (Monocotylidae: Heterocotylinae), from the gills of Himantura walga (Dasyatidae) off Sarawak, Borneo

Septesinus gibsoni n. g., n. sp. (Monocotylidae: Heterocotylinae) is described from the gills of the dwarf whipray Himantura walga (Müller & Henle) collected in marine waters off Sarawak (Borneo), Malaysia. Septesinus n. g. is distinguished from other genera in the Monocotylidae by a combination of characters, including a haptor with one central and seven peripheral loculi, the presence of a highly sinuous ridge surmounting all haptoral septa, four rounded accessory structures on the dorsal surface of the haptor, and the anterior region with two pairs of anteromedian and three pairs of anterolateral gland-duct openings. Septesinus n. g. is accommodated in the Heterocotylinae. Septesinus gibsoni n. sp. is described and fully illustrated, and a key to the genera of Heterocotylinae is provided. The composition of the ridges surrounding the mouth of a number of heterocotyline species and their usefulness as a taxonomic character are examined. The identity of four specimens of Monocotyle Taschenberg, 1878, also recovered from the gills of this host species, is discussed.

Malalophus jensenae n. g., n. sp. (Monogenea: Monocotylidae) from the gills of Aetomylaeus vespertilio (Myliobatidae) off northern Australia

Malalophus jensenae n. g., n. sp. is described from the gills of the ornate eagle ray Aetomylaeus vespertilio (Bleeker) collected off the eastern coast of the Gulf of Carpentaria, northern Queensland. The new genus is similar to Heliocotyle Neifar, Euzet & Ben Hassine, 1999, with which it shares a haptor bearing seven peripheral loculi and a single dorsal haptoral accessory structure. M. jensenae can be distinguished from species of Heliocotyle by the presence of numerous sclerotised sinuous ridges covering the ventral surfaces of the peripheral loculi of the haptor. It also lacks pseudosepta which are present on the haptor of Heliocotyle species. This is the first published record of a monogenean from an elasmobranch in the Gulf of Carpentaria, Australia.

Revision of Potamotrygonocotyle Mayes, Brooks & Thorson, 1981 (Platyhelminthes: Monogenoidea: Monocotylidae), with descriptions of four new species from the gills of the freshwater stingrays Potamotrygon spp. (Rajiformes: Potamotrygonidae) from the La Plata river basin

The only known monocotylid genus to parasitise Neotropical freshwater stingrays (Potamotrygonidae) is Potamotrygonocotyle Mayes, Brooks & Thorson, 1981, a monotypic genus erected to accommodate P. tsalickisi Mayes, Brooks & Thorson, 1981. For more than 20 years, no other species has been recognised in this genus, but new efforts to survey the diversity of parasites inhabiting potamotrygonids have revealed the existence of new species and the need to redefine the genus. Here, the generic diagnosis of Potamotrygonocotyle is amended, P. tsalickisi is redescribed and four new species are recognised and described based on samples collected from the gills of freshwater potamotrygonids from the La Plata river basin: Potamotrygonocotyle chisholmae n. sp. and P. dromedarius n. sp. from Potamotrygon motoro; Potamotrygonocotyle eurypotamoxenus n. sp. from Potamotrygon cf. motoro (type-host), P. castexi, P. falkneri and P. histrix; and Potamotrygonocotyle uruguayensis n. sp. from Potamotrygon brachyura. Potamotrygonocotyle is characterised by species possessing: (1) slightly sinuous sclerotised ridges on all septa; (2) two pairs of the dorsal haptoral accessory structures associated with the four posterior peripheral loculi and with anterior dorsal haptoral accessory structure bilobate or semicircular; and (3) male copulatory organ without an accessory piece.

Euzetia occultum n. g., n. sp. (Euzetiinae n. subf.), a monocotylid monogenean from the gills of Rhinoptera neglecta (Rhinopteridae) from Moreton Bay, Queensland, Australia.

Euzetia occultum n. g., n. sp. (Monogenea: Monocotylidae) is described from the gills of the Australian cownose ray Rhinoptera neglecta Ogilby collected in Moreton Bay, Queensland, Australia. Euzetia has one central and ten peripheral loculi, which is similar to species in Decacotyle Young, 1967. However Euzetia is distinguished from other genera in the family by the presence of an additional loculus on either side of the central loculus. Because Euzetia does not fit into any of the six existing subfamilies in the Monocotylidae Taschenberg, 1879, as currently recognised, we propose the Euzetiinae n. subf. to accommodate the new genus. Euzetia occaltum is described and illustrated fully. This is the first published record of a monocotylid from a species of Rhinoptera Cuvier.

Heliocotyle ewingi sp. n. (Monogenea: Monocotylidae) from the gills of Myliobatis australis (Myliobatididae) from Tasmania, Australia.

Heliocotyle ewingi sp. n. (Monogenea: Monocotylidae) is described from the gills of Myliobatis australis Macleay, 1881 (Myliobatididae) collected from Norfolk Bay near Hobart, Tasmania, Australia. Heliocotyle ewingi can be distinguished readily from the only other species in the genus, Heliocotyle kartasi Neifar, Euzet et Ben Hassine, 1999, by the presence of a single pseudoseptum on each of the peripheral loculi except the posteriormost, eyespots and by the morphology of the male copulatory organ which is a short, straight sclerotised tube which lacks a sclerotised accessory piece. The generic diagnosis is revised to accommodate the new species and the anterior glands are discussed.

Merizocotyle-Icopae, Sp-Nov, and Thaumatocotyle-Australensis, Sp-Nov, (Monogenea, Monocotylidae) From the Nasal Cavities of Rajiform Elasmobranchs of the Great-Barrier-Reef

Monocotylid monogeneans were found in the nasal cavities of rajiform fishes taken off Heron I., Great Barrier Reef. Merizocotyle icopae, sp. nov., is proposed for worms from Rhinobatos batillum and differs from all other named Merizocotyle spg in that the haptor has five loculi arranged symmetrically round the central depression, and 18 peripheral loculi. Also, eye spots are present. Thaumatocotyle australensis, sp. nov., is proposed for worms from Himantura uarnak and differs from all other named Thaumatocotyle spp. in the morphology of the penis and the presence of a conspicuously muscular accessory genital bulb. In order to accommodate the new species emended generic diagnoses are provided, and the diagnoses for the Monocotylidae and Merizocotylinae are modified.

A Rare Cœlom-Dwelling Trematode

CŒLOM-dwelling trematodes are very rare. The only monogenetic form ever found in the cœlom of a vertebrate is Dictyocotyle cœliaca Nybelin, 1941. A solitary specimen was found at Goteborg on April 1, 1940, attached to the surface of the liver in a ray (Raja lintea Fries) caught the previous day near Skagen. At first sight the trematode was mistaken for the well-known cloacal parasite Calicotyle kroyeri, but closer inspection revealed several distinctive characters, notably the irregular arrangement of numerous shallow loculi on the posterior disk (opisthaptor), which was devoid of hooks, the reticular nature of the testes and the five finger-like terminations of the filiform ovary1. In contrast, the opisthaptor of Calicotyle has one central loculus and seven peripheral loculi and bears one pair of hooks with recurved points, the testes are diffuse and follicular and the ovary terminates in a single lobe.