Anterior Hamuli Research Articles

Redescription ofAllobenedenia dischizosepta(Suriano, 1975) n. comb. (Monogenoidea: Capsalidae: Trochopodinae) from the Gills of Argentine Sea Basses (Acanthistius) in the Southwestern Atlantic Ocean

We herein redescribe Allobenedenia dischizosepta (Suriano, 1975) n. comb. (Monogenoidea: Capsalidae) based on light microscopic analysis of the holotype and 18 paratypes from the gill of Acanthistius brasilianus (Cuvier, 1828) (Perciformes: Serranidae) along with light and scanning electron microscopy of 25 newly collected specimens from the gill of Acanthistius patachonicus (Jenyns, 1842) (new host record) in the southwestern Atlantic Ocean off Argentina. Contradicting the original description of this species and its generic diagnosis, all specimens had 5 loculi (2 anterior plus 3 posterior loculi) plus 5 corresponding haptoral septa only (central loculus absent). The original description of this species erroneously specified 6 loculi, including 2 small anterolateral loculi. Because A. dischizosepta was the type species for Tetrasepta Suriano, 1975 and because it fits the diagnosis of Allobenedenia Yamaguti, 1963, the genus therefore is regarded a junior synonym of Allobenedenia. Allobenedenia dischizosepta differs from its congeners by lacking a haptoral peduncle as well as by having 5 haptoral loculi, accessory sclerites that lack a conspicuous dorsal protuberance and that are weakly bifid, by posssesing robust anterior hamuli that are strongly recurved for half of their total length, by having a male accessory gland reservoir in the extreme posterior portion of the penis sac and lateral to the vitelline reservoir abutting the ovary, and by the presence of a straight (not coiled) proximal portion of the ejaculatory duct within the penis sac.

New Benedenia Species (Monogenea: Capsalidae) from Diagramma labiosum (Perciformes: Haemulidae) On the Great Barrier Reef, Australia, With Oncomiracidial Descriptions and A Report of Egg Attachment to the Host

The slate sweetlips, Diagramma labiosum Macleay, 1883 (Perciformes: Haemulidae), off Heron Island, Great Barrier Reef, Queensland, Australia, hosts 2 new species of Benedenia Diesing, 1858 (Monogenea: Monopisthocotylea: Capsalidae). Benedenia beverleyburtonae n. sp. infects proximal regions of the primary gill lamellae and gill arches. The adult is characterized by a dorsal vaginal pore anterior to the common genital pore and a voluminous, highly coiled vas deferens. This species also has fine muscle fibrils concentrically arranged in the haptor. Its ciliated oncomiracidium differs little from larvae of other Benedenia species, with the exception of at least 4 gland cells containing a granular secretion on each side of the body at the level of the excretory bladders, with fine ducts opening anterior to the eyes. Benedenia disciliata n. sp. infects gill arches and gill rakers, and the adult is characterized by its small total length, anterior hamuli with a small proximal notch, posterior hamuli with a broad, triangular shape proximally, a conspicuous internal fertilization chamber, and asymmetrical eggs. None of the 5 specimens collected had testes, but their definite absence is undetermined. Their absence and the fact that the vas deferens was discernable only distally in the specimens of B. disciliata examined may represent atrophying of the male organs. Benedenia disciliata is unique among Benedenia species because eggs are attached to the host's gill arches by tight wrapping of the appendages around spines on the gill rakers and the larva is not ciliated. Among Capsalidae species, these features are shared only with species of Dioncus Goto, 1899. Recent molecular evidence has indicated Benedenia is polyphyletic, but with no clear morphological characters available to divide the genus, the 2 new species fit the current concept for the genus more closely than other capsalid genera. Proposal and description of these taxa and accounts of their oncomiracidia and other aspects of their biology indicate potentially useful characters for division of the genus in the future.

Revision of Benedeniella Johnston, 1929 (Monogenea: Capsalidae), its assignment to Entobdellinae Bychowsky, 1957 and comments on subfamilial composition

Benedeniella macrocolpa (Lühe, 1906) Yamaguti, 1963 is redescribed from new material collected from ventral skin surfaces of the Australian cownose ray, Rhinoptera neglecta Ogilby (Elasmobranchii: Myliobatidae) from waters in Moreton Bay and from captive rays in a public display aquarium in Townsville, from R. cf. neglecta and Rhinoptera sp. from Weipa, Queensland, Australia and from R. javanica Müller & Henle caught in the Arabian Gulf north of Dubai, United Arab Emirates. Benedeniella posterocolpa (Hargis, 1955) Yamaguti, 1963 is redescribed from new specimens collected from the cownose ray, R. bonasus (Mitchill) (Myliobatidae) from several localities in the Gulf of Mexico and in the Chesapeake Bay region of the south-eastern and eastern USA, respectively. Detailed anatomical redescriptions demonstrate that each Benedeniella species share several dorsal structures (paired anterior horns, excretory papillae and posterior conical structures at the junction of the body with the haptor), anterolateral grooves on the ventral surface of each anterior attachment organ, a similar route for tendons associated mostly with the accessory sclerites and the anterior hamuli and a long vagina. The different path of the vagina and the position of the vaginal pore are the simplest characters to discriminate the two species. Benedeniella unnithani Gupta & Chanana, 1976 from the gills of a Caranx sp. (Teleostei: Perciformes: Carangidae) off Kavaratti, Laccadive Islands, Arabian Sea, India is considered a species incertae sedis. Morphological parallels are identified, in particular concerning the anterior attachment organs of species in Benedeniella, Branchobdella Kearn, Whittington & Evans-Gowing, 2007, Entobdella Blainville in Lamarck, 1818, Neoentobdella Kearn & Whittington, 2005 and Pseudoentobdella Yamaguti, 1963. Of these entobdelline genera, species in three of them parasitise principally the skin of elasmobranch rays (Dasyatidae; Myliobatidae; Rhinobatidae); only species in Branchobdella and Entobdella parasitise flatfish teleosts (Paralichthyidae; Pleuronectidae; Soleidae). On the basis of the redescriptions presented here plus morphological similarities, host associations and recently published molecular genetic data, Benedeniella is moved from the Benedeniinae Johnston, 1931 and the diagnosis for the Entobdellinae Bychowsky, 1957 is amended to unite Benedeniella, Branchobdella, Entobdella, Listrocephalos Bullard, Payne & Braswell, 2004, Neoentobdella and Pseudoentobdella. The affinities of species in a seventh capsalid genus, Trimusculotrema Whittington & Barton, 1990 (currently in Benedeniinae), are considered briefly based on morphology and host association and reassigned to the Entobdellinae.

A revision of Entobdella Blainville in Lamarck, 1818, with special emphasis on the nominal (type) species “Entobdella hippoglossi (Müller, 1776) Blainville, 1818” (Monogenea: Capsalidae: Entobdellinae) from teleost flatfishes, with descriptions of three new species and a new genus

Species of Entobdella Blainville in Lamarck, 1818, from skin (less commonly gills) of teleost flatfishes and occasionally from round-bodied teleosts are reviewed, with special reference to the nominal (type) species “Entobdella hippoglossi (Müller, 1776) Blainville, 1818” (Monogenea: Capsalidae: Entobdellinae) and to E. pugetensis Robinson, 1961. In the late 20th century the following 5 species were synonymised with E. hippoglossi: E. brattstroemi Brinkmann, 1952; E. curvunca Ronald, 1957; E. rosaceus Crane, 1972; E. squamula (Heath, 1902) Johnston, 1929; E. steingroeveri (Cohn, 1916) Johnston, 1929. We have shown that E. brattstroemi and E. squamula are valid, E. curvunca is a synonym of E. hippoglossi and E. rosaceus and E. steingroeveri are species inquirendae. Specimens of E. steingroeveri, first described in 1916 by Cohn, have been re-examined. Parasites from the Pacific Ocean on Hippoglossus stenolepis Schmidt, 1904 (Pacific halibut) and Eopsetta jordani (Lockington, 1879) (Petrale sole) (Pleuronectiformes: Pleuronectidae) and parasites geographically isolated in the Atlantic Ocean on H. hippoglossus (Linnaeus, 1758) (Atlantic halibut) and Reinhardtius hippoglossoides (Walbaum, 1792) (Greenland halibut) (Pleuronectiformes: Pleuronectidae) have all been regarded as E. hippoglossi. We confirm that E. hippoglossi sensu stricto is a parasite of the Atlantic halibut, but is accompanied on the same host by a second entobdelline species, E. vanbenedeni n. sp. It differs from the type species, E. hippoglossi in the anatomy of the distal region of the vagina and in the number, distribution and shape of papillae on the ventral surface of the haptor. Parasites from H. stenolepis are morphologically similar to E. hippoglossi on H. hippoglossus (no second species has been found on H. stenolepis), but differences in the number and shapes of haptor papillae support proposal of the parasites from H. stenolepis as a distinct species, E. stenolepis n. sp. Our anatomical studies of these parasites, with the exception of E. pugetensis, have revealed a cluster of several seminal receptacles opening into the ovo-vitelline duct. Previous reports of a single seminal receptacle in E. stenolepis (as E. hippoglossi) and E. steingroeveri are erroneous. Furthermore, reports of the vagina opening proximally into the alleged single seminal receptacle are also incorrect; direct and indirect evidence suggests that in all these parasite species, including E. pugetensis, the vagina opens proximally into the vitelline reservoir. Entobdella squamula from Paralichthys californicus (Ayers, 1859) (California flounder) (Pleuronectiformes: Paralichthyidae) differs from E. stenolepis, E. hippoglossi and E. vanbenedeni in the relative lengths of the accessory sclerites and anterior hamuli. Parasites originally identified as E. squamula from Hippoglossina macrops Steindachner, 1876 (Bigeye flounder) (Pleuronectiformes: Paralichthyidae), caught off the coast of Chile by the Lund University Chile Expedition (1948 – 49), differ from E. squamula in the shapes of the accessory sclerites and are regarded as a new species, E. brinkmanni n. sp. E. aegyptiacus Amer, 1990 must be regarded as a species inquirenda. A key to the 7 valid species of Entobdella recognised by us is included. Entobdella pugetensis differs in the following ways from all other species of Entobdella: the parasite is found on gills (less commonly on skin) of Atheresthes stomias (Jordan & Gilbert, 1880) (Arrowtooth flounder) (Pleuronectiformes: Pleuronectidae); the penis sac has a thick, possibly muscular, wall; the vagina is a relatively wide, short, straight tube with a conspicuous opening; no seminal receptacles have been observed; there are no papillae on the ventral surface of the haptor. We regard these distinctions as sufficient to erect a new genus, Branchobdella n. gen. to accommodate B. pugetensis n. comb. Assimilation of spermatophores in skin-parasitic Entobdella spp. and in the gill parasite B. pugetensis is discussed.

The precocious oncomiracidium of Neoentobdella parvitesticulata (Monogenea: Capsalidae: Entobdellinae)

The oncomiracidium (larva) of the entobdelline Neoentobdella parvitesticulata (Monogenea: Capsalidae), adults of which parasitise the skin of the stingray Himantura fai (Dasyatidae) at Heron Island, Great Barrier Reef, Queensland, Australia, is described. The larva undergoes precocious development (progenesis) in the freely deposited egg. At >600 microm long, the fully embryonated, free-swimming oncomiracidium is more than twice as long as the larva of the related species N. diadema. Furthermore, the larva of N. parvitesticulata has a total of 60 flame bulbs compared with only 18 in N. diadema. The anterior hamuli in the oncomiracidium of N. parvitesticulata have well-developed distal hooks and may already be functional for secure attachment whereas those of N. diadema are rod-shaped, have no distal hook and would be unable to function in this way in newly attached larvae.

A New Species of Metabenedeniella (Monogenea: Capsalidae) from the Dorsal Fin of Diagramma pictum (Perciformes: Haemulidae) from the Great Barrier Reef, Australia with a Revision of the Genus

Metabenedeniella parva n. sp. is described from the marine teleost Diagramma pictum from Heron Island, Queensland, Australia. The type species of the genus, Metabenedeniella hoplognathi, is redescribed and the generic diagnosis emended. Metabenedeniella parva differs from M. hoplognathi in many respects: M. parva is smaller; in M. parva the accessory sclerites and anterior hamuli are of similar length, but the posterior hamuli are smaller, whereas in M. hoplognathi the accessory sclerites are longer than the anterior hamuli and the anterior and posterior hamuli are of similar length; in M. parva the anterior hamuli span the distance between accessory sclerites and posterior hamuli and the anterior hamuli overlap the posterior hamuli considerably, but in M. hoplognathi the anterior hamuli partially overlap the posterior hamuli and do not extend anteriorly to reach the accessory sclerites; a sclerite close to the common genital aperture in M. parva is absent from M. hoplognathi. The 2 species differ also in some of their soft body parts. Specimens reported previously from the gills of Plectorhynchus chaetodonoides off Okinawa, Japan as M. hoplognathi are considered to be M. parva. The discovery of M. parva from only the dorsal fin of D. pictum at Heron Island enhances the notion that some benedeniine monogeneans from the body surfaces of fish exhibit strong site specificity.

The rate of development and longevity of the monogenean skin parasite Entobdella soleae

Using soles (Solea solea) infected experimentally with oncomiracidia of the monogenean skin parasite Entobdella soleae, it was found that the parasite begins to assemble eggs at about 85 days post infection and may survive for as long as 6 1/2 months at 12 +/- 1 degrees C. Growth of the anterior hamuli continues throughout life but the growth rate decreases with time. The oldest (largest) parasites recovered from laboratory soles were similar in size to the largest parasites collected in the wild.