Empruthotrema stenophallus n. sp. (Monogenea: Monocotylidae) from the nasal tissue of Dasyatis kuhlii (Dasyatidae) from Sabah, Borneo, Malaysia

Empruthotrema stenophallus n. sp. (Monogenea: Monocotylidae) is described from specimens from the nasal tissue of the blue-spotted maskray Dasyatis kuhlii (Muller and Henle, 1841) collected in shallow waters off Pulau Banggi and Pulau Mabul, Sabah, Borneo, Malaysia. This is the first monogenean species to be described from an elasmobranch collected from Sabah. E. stenophallus can be distinguished from the other 6 members of the genus by the morphology of the sclerotized male copulatory organ, which is narrow, short, and distally tapered. E. dasyatidis Whittington and Kearn, 1992, previously documented from the nasal tissue of several of elasmobranch species from Australia, is recorded from 8 host species distributed around Malaysian Borneo. These represent new host and locality records for this monocotylid. The difficulties in identifying species of Empruthotrema and the apparent lack of host specificity by some members of the genus are discussed.     

Rhinebothrium xiamenensis n. sp. (Eucestoda: Tetraphyllidea) in Dasyatis zugei from the coast of Xiamen, China

A new species of Rhinebothrium inhabiting Dasyatis zugei is reported from the southeast coast of China. This is the first report of Rhinebothrium from D. zugei. It represents a new host and a new location. The new species resembles Rhinebothrium corymbum by having a V-shaped ovary. It differs in the fewer loculi and testes numbers, longer bothrium pedicel and cephalic peduncle, larger cirrus pouch and vitelline follicles, and an aspinose peduncle. Rhinebothrium xiamenensis differs from Rhinebothrium ezuti, Rhinebothrium walga, and Rhinebothrium hawaiiensis by having discrete vitelline follicles, fewer loculi, and ovarian shape.     

Empruthotrema dasyatidis n. sp. (Monogenea: Monocotylidae) from the olfactory sacs of Dasyatis fluviorum (Rajiformes: Dasyatidae) from Moreton Bay,Queensland

The monocotylid monogenean Empruthotrema dasyatidis n. sp. is reported from the olfactory sacs of the brown stingray, Dasyatis fluviorum Ogilby, 1908, from Moreton Bay, Queensland, Australia. This is the first record of Empruthotrema from the family Dasyatidae. E. dasyatidis n. sp. differs from other species of Empruthotrema by possessing eye pigment, which may be scattered, and by its small size. The generic diagnosis for Empruthotrema is amended.     

New data on the reproductive biology of the thorny stingray,Dasyatis centroura (pisces: Dasyatidae) from off the Tunisian coasts

Synopsis Aspects of the reproductive biology are described for the thorny stingray,Dasyatis centroura, caught off the coasts of Tunis, mainly from the Gulfs of Gabes and Tunis. Sexual maturity in males occurs at a disk width (DW) of 800 mm. Female maturation occurs between 660 mm and 1000mm DW All males and females having a DW greater than 800 and 1000mm, respectively, were adults. Females are larger than males, with adult specimens having an average DW of 1040mm in males and 1345mm in females. Gestation lasts for a minimum of about 4 months. The number of reproductive cycles per year is unknown. Vitellogenesis is completed at the end of the gestation. Parturition and ovulation occur in June. Fecundity ranges from 2 to 6 individuals per litter.     

Dendromonocotyle lasti n. sp. from the skin and Monocotyle caseyae n. sp. (Monogenea: Monocotylidae) from the gills of Himantura sp. (Dasyatidae) in Moreton Bay, Queensland, Australia

Seven specimens of rays of the genus Himantura which could not be identified to species were collected from waters near Dunwich, Stradbroke Island, Moreton Bay, Queensland, Australia. The five smallest specimens of Himanturasp. (disc width 218-302 mm; four female, one male) had a banded tail and the dorsal surface was uniformly grey/brown. The two largest individuals of Himantura sp. (disc widths 460, 533 mm; female and male, respectively) also had a banded tail but the grey/brown dorsal surface had white spots. Two new monogenean species (Monocotylidae: Monocotylinae) are described from both the plain and white-spotted specimens of Himantura. Dendromonocotyle lastin. sp. is distinguished from other species in the genus by the number of papillae on the haptor, by the morphology of the male copulatory organ and by the morphology of the proximal portion of the vagina. The muscular sheath which surrounds the male copulatory organ is also unique having sclerotised spines at the distal end. Dendromonocotyle species are skin parasites, but a total of five juvenile specimens of D. lasti were found on the gills of four rays. Monocotyle caseyae n. sp. from the gills is characterised by the morphology of the male copulatory organ and its accessory piece. One specimen of M. spiremae Measures, Beverley-Burton & Williams, 1990, originally described from the gills of Himantura fai Jordan & Seale off Heron Island, Great Barrier Reef, Queensland, Australia, was also found on the gills of one Himantura specimen. The site and host-specificity of the parasites and the identity of the hosts are discussed.     

A new species of Thaumatocotyle (Monogenea: Monocotylidae) from Dasyatis sabina (Myliobatiformes: Dasyatidae) off the coast of South Carolina

Thaumatocotyle roumillati n. sp. is described from specimens collected in the nasal fossae of the Atlantic stingray, Dasyatis sabina (Lesueur) from the southeastern coast of the United States, off South Carolina. Thaumatocotyle roumillati is distinguished from congeners by the size and shape of its penis as well as the presence of a spinelike accessory piece associated with the penis.     

Hypanocotyle bullardi n. gen. n. sp. (Monogenea: Hexabothriidae) from gill of the diamond stingray Hypanus dipterurus (Jordan et Gilbert) (Myliobatiformes: Dasyatidae) in the Southeastern Pacific Ocean off Peru

A new genus and species of monogenean belonging to Hexabothriidae, Hypanocotyle bullardi n. gen. n. sp., is described based on specimens collected from the gill filaments of the diamond stingray, Hypanus dipterurus (Jordan et Gilbert) (Myliobatiformes: Dasyatidae), a demersal chondrichthyan collected off the coast of Callao, Peru. Hypanocotyle n. gen. has the following combination of diagnostic features that differentiate it from other hexabothriid genera: haptor symmetrical; vasa efferentia having proximal (narrow, with thin glandular wall) and distal (expanded, interlaced, with thick glandular wall) portions, joining medially to form vas deferens; vas deferens having proximal (expanded, sinuous, with thick glandular wall) and distal (narrow, strongly sinuous, with thin glandular wall) portions; male copulatory organ unarmed, proximal portion slightly sinuous and tube-like, distal portion funnel-shaped; prostatic glands present, distributed around of the MCO; seminal receptacle present; ootype lacking longitudinal rows of large cells (no oötype côtelé); vaginae parallel, with well-differentiated proximal (glandular, narrow, tube-like, slightly sinuous) and distal (musculoglandular, convoluted) portions; gland cells surrounding the vaginal duct along the entire length of distal portion, densely clustered in middle portion; uterine eggs with 2 elongate filaments. Phylogenetic reconstructions by maximum-likelihood method, based on newly obtained partial 18S and 28S sequences, shows that H. bullardi n. gen. is included within the family Hexabothriidae, order Diclybothriidea. This is the second hexabothriid genus recorded from a diamond stingray (Dasyatidae), and the fourth hexabothriid species recorded from Peru. A key to hexabothriid genera is provided.     

A new species of Monocotyle taschenberg, 1878 (Monogenea: Monocotylidae) from Dasyatis guttata (Dasyatidae)

Monocotyle guttatae n. sp. is described from the gills of the ray Dasyatis guttata (Bloch and Schneider, 1801) (Dasyatidae) off the coast of Brazil The new species can be readily differentiated from the other species of the genus in having a male copulatory organ with 2 loops and an accessory piece, 5-7 sclerites on the marginal haptoral papillae, and the absence of accessory sclerites on the dorsal surface of the posterior body. The present record confirms the presence of the genus in the subtropical waters of South America.     

Neobenedenia pargueraensis n. sp. (Monogenea: Capsalidae) from the red hind, Epinephelus guttatus, and comments about Neobenedenia melleni.

Neobenedenia pargueraensis n. sp. from Epinephelus guttatus of Puerto Rico differs from all known species in possessing scoop-shaped accessory sclerites with pointed tips. It is most similar to Neobenedenia melleni and Neobenedenia longiprostata but differs from the former in having a fenestrate ovary and from the latter in that the ducts of the accessory glands are short, terminating just anterior to the vitelline reservoir rather than reaching the caudal end of the body. It differs from both species in having smooth rather than lobate testes. Neobenedenia melleni occurs throughout the tropical and subtropical western North Atlantic including Bermuda. It kills aquarium and aquaculture fishes with massive infestations and is a severe restraint on the culture of tilapia in sea water in the Caribbean.     

Structure of the testis and genital duct of freshwater stingray, Himantura signifer (Elasmobranchii: Myliobatiformes: Dasyatidae)

The light microscopic structure of the testis and genital duct system of the freshwater stingray Himantura signifer was observed. The testis is composed of lobes having numerous spermatocysts in a dorsoventral zonated arrangement. The germinal papilla at the middorsal surface of the testicular lobe is the origin site of spermatocyst development, where mesenchymal-like cells are predominantly found. The association of a Sertoli cell precursor with a spermatogonium marks the onset of spermatocyst formation and development. The newly formed spermatocysts at the dorsal end of the germinal zone replace the older ones, which are sequentially moved to the ventral side and are termed spermatogonial, spermatocyte, spermatid, spermatozoal, and degenerate zones. In the degenerate zone, the spermatocysts deteriorate after releasing the spermatozoa into the intratesticular duct, where they are further transported through the extratesticular duct system and finally stored at the seminal vesicle. The epithelial lining of the genital duct is a pseudostratified ciliated columnar with no muscular layer underneath; thus, sperm are conveyed through ciliary activity. The interesting features of the present study are the finding of mesenchymal-like cells in the germinal papilla and the nonaggregated formation of sperm in the seminal vesicle.     

Occurrence of lymphohaemopoietic tissue in the meninges of the stingray Dasyatis akajei (Elasmobranchii, chondricthyes)

The cytoarchitecture of the lymphohaemopoietic masses occurring in the "meninx primitiva" of the stingray Dasyatis akajei (Elasmobranchii, Chondricthyes) has been analyzed by light and scanning and transmission electron microscopy. Lymphohaemopoietic aggregates showing similar morphologies occurred along all the central nervous system, but they were more frequent in the telencephalon, diencephalon, and mesencephalon. In each aggregate, the granulopoietic tissue appeared in a fibroblastic stroma surrounding the large blood vessels, and the lymphoid components were present in a reticular network. Developing and mature eosinophils and heterophils--as well as lymphocytes, monocytes, macrophages, and plasma cells--are the main free cells present in these meningeal aggregates. The remarkable intimate association between macrophages and lymphoid cells to form close cell clusters suggests some immunological capacity for the meningeal lymphohaemopoietic tissue. According to their capacities, presence of lymphoid tissue, and histological organization, the meningeal lymphohemopoietic aggregates of Dasyatis akajei resemble other lymphomyeloid aggregates associated with cranium and choroid plexuses in Holocephali and Ganoidei. The phylogenetical relationships of these aggregates with mammalian bone marrow are discussed.     

Reproductive Strategies of the Insidious Fish Ectoparasite,Neobenedenia sp. (Capsalidae: Monogenea)

Fish monogeneans are lethal parasites in aquaculture. We provide the first experimental evidence that a notorious fish monogenean, Neobenedenia sp., can produce viable eggs in isolation for three consecutive generations. We infected individual, isolated, farmed barramundi, Lates calcarifer (Bloch) with a single oncomiracidium (larva) of the hermaphroditic monogenean Neobenedenia sp. Isolated parasites reached sexual maturity at day 10 post-hatch (24°C, 35‰) and laid ∼3,300 embryonated eggs over 17 days. Egg production rapidly increased following sexually maturity on day 10 (58±15 eggs) and peaked on day 15 (496±68 eggs) before gradually decreasing. Neobenedenia sp. exhibited egg laying and egg hatching rhythms. Parasites laid eggs continuously, but egg production increased in periods of darkness (64.3%), while the majority of oncomiracidia (81%) emerged from eggs in the first three hours of light. Eggs laid by isolated ‘parent’ parasites hatched and individual emerging oncomiracidia were used to infect more individual, isolated fish, with three consecutive, isolated, parasite generations (F1, F2 and F3) raised in the laboratory. Infection success and egg hatching success did not differ between generations. Our data show that one parasite, in the absence of a mate, presents a severe threat to captive fish populations.     

The subfamily Encotyllabinae (Monogenea: Capsalidae) with the description of Alloencotyllabe caranxi n. g., n. sp. and Encotyllabe kuwaitensis n. sp.

Alloencotyllabe caranxi n. g., n. sp. is found in groups of 9–15 specimens attached close together to the lower pharyngeal plate of Caranx sp. It is characterized by having an elongate body, a prohaptor with large spines, an armed penis which lies in a pouch and a vaginal pouch guarded by two sets of glands. Encotyllabe kuwaitensis n. sp. is attached individually to the lower pharyngeal plate of Caranx sp. It is characterized by having an elongate body and tandem testes. E. spari is reported from the lower pharyngeal tooth plate of Plectorhynchus cinctus, P. pictus and P. schotaf. All fish hosts were caught in Kuwaiti waters in the Arabian Gulf. The subfamily Encotyllabinae is reviewed and the genus Neoencotyllabe is regarded as a genus inquirendum. The new genus is attached to the subfamily Encotyllabinae.     

<Emphasis Type="Italic">Decacotyle cairae</Emphasis> n. sp. (Monogenea: Monocotylidae) from the gills of <Emphasis Type="Italic">Pastinachus</Emphasis> sp. (Elasmobranchii: Dasyatidae) from the South China Sea off Sarawak,Borneo, Malaysia

Decacotyle cairae n. sp. (Monogenea: Monocotylidae) is described from the gills of an unidentified species of Pastinachus collected in the South China Sea off Sematan and Mukah, Sarawak, Borneo, Malaysia. D. cairae can be distinguished from the other six members of the genus by the presence of two simple unsclerotised accessory structures on the dorsal surface of the haptor in combination with a long, narrow, looping male copulatory organ. The host specimens of Pastinachus collected in Borneo also appear to be a new species and the monogenean data support this conclusion. A key to species of Decacotyle is given and their host-specificity is discussed.     

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.     

Dasyatis laosensis,a new whiptailed stingray (family Dasyatidae), from the Mekong River of Laos and Thailand

Synopsis Dasyatis laosensis, a new species, is described from the Mekong River where it forms the border between Laos and Thailand. It is the first member of the genus Dasyatis to be described as an endemic freshwater species from Southeast Asia. Bright orange color on the ventral surface of the disc and similar meristic characters indicate that it may be closely related to Dasyatis akajei, a marine species from southern Japan and China, and to Dasyatis sp. undetermined, from the West River in Guangxi, southern China.     

A new species of Heterocotyle Scott, 1904 (Monogenea: Monocotylidae) from the gills of Dasyatis guttata (Dasyatidae) in southwestern Atlantic waters off Rio de Janeiro, Brazil

Heterocotyle sulamericana n. sp. is described from the gills of Dasyatis guttata (Bloch & Schneider) caught off the coast of Brazil near Rio de Janeiro. This species can be distinguished from all other members of Heterocotyle Scott, 1904 by a combination of the morphology of the male copulatory organ, which is a short, slightly curved, sclerotised tube with no accessory piece, and the haptor, which has a single ridge surmounting all septa. This is the first Heterocotyle species to be described from the southwestern Atlantic.     

Laticola dae n. sp. (Monogenea: Diplectanidae) from Epinephelus maculatus (Perciformes: Serranidae) off New Caledonia

Laticola dae n. sp. is described from specimens collected from the gill-filaments of the highfin grouper Epinephelus maculatus, a coral reef fish caught off Nouméa, New Caledonia, South Pacific. The species is characterised by a spoon-shaped sclerotised male copulatory organ, with four thin walls and 73–m in outer length, and a sclerotised vagina in form of a disc, 16–m in diameter, with a smaller hemisphere on one side. Laticola Yang et al., 2006 was described to accommodate diplectanids from Lates calcarifer (Centropomidae); this is the first Laticola described from a serranid. Other diplectanids, including several species of Pseudorhabdosynochus Yamaguti, 1958, were also found on the same species of fish; specimens of L. dae represented about half of the diplectanids collected; all other species were rare.

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Résumé Laticola dae n. sp. est décrit à partir de spécimens collectés sur les filaments branchiaux de la loche grisette, Epinephelus maculatus, un poisson de récif corallien pêché au large de Nouméa, Nouvelle-Calédonie, Pacifique Sud. L’espèce est caractérisée par un organe copulateur mâle sclérifié en forme de cuiller, avec quatre parois fines, long de 73–m, et un vagin sclérifié en forme de disque, de diamètre 16–m, avec un hémisphère plus petit d’un côté. Laticola Yang et al., 2006 a été décrit pour rassembler des Diplectanidae de Lates calcarifer (Centropomidae) ; ceci est le premier Laticola décrit d’un Serranidae. D’autres Diplectanidae, y compris plusieurs espèces de Pseudorhabdosynochus, ont aussi été trouvés chez ce poisson ; les spécimens de L. dae représentaient environ la moitié des Diplectanidae récoltés, toutes les autres espèces étaient rares.