Benedenia epinepheli ( Yamaguti, 1937 ) Meserve, 1938

Whittington, I. D., Deveney, M. R. & Wyborn, S. J., 2001, A revision of Benedenia Diesing, 1858 including a redescription of B. sciaenae (van Beneden, 1856) Odhner, 1905 and recognition of Menziesia Gibson, 1976 (Monogenea: Capsalidae), Journal of Natural History 35 (5), pp. 663-777 : 694-698

Benedenia epinepheli ( Yamaguti, 1937) Meserve, 1938

(®gures 16B, 18, 19D±F)

Synonyms. Epibdella (Epibdella) epinepheli Yamaguti, 1937 ; Benedeniella congeri Yamaguti, 1958 ; Neobenedeniella congeri ( Yamaguti, 1958) Yamaguti, 1963 ; Benedenia sp. of Tsutsumi and Ito (1965); Benedenia congeri ( Yamaguti, 1958) Byrnes, 1986 .

Material studied. MPM: No. 22771 (holotype and paratypes) (1 slide, 5 individuals including 1 immature specimen) ex gills of Epinephelus akaara (Temminck and Schlegel) (Serranidae) from Tarumi, Japan; KO: (2 slides; 1 slide with 2 individuals from unspeci®ed site from unspeci®ed host from Shimonoseki Aquarium, Yamaguchi Prefecture and used by Tsutsumi and Ito (1965); 1 slide with 6 individuals ex body surface and ®ns of Paralichthys olivaceus (Temminck and Schlegel) (Paralichthyidae) from Yonouzu, Oita Prefecture; MPM: No. 22356 Benedenia congeri ( Yamaguti, 1958) Byrnes,1986 [labelled as Benedeniella congeri ] (holotype) (1 slide, 1 individual) ex gills of Conger myriaster (Brevoort) (Congridae) .

All these specimens (13), except the immature individual mounted with the holotype, were measured. Comparative measurements are presented in table 2.

Observations. When we began this study, the only specimens of B. epinepheli available were the types. Of these ®ve specimens, one is immature and of little use and two specimens are poorly ®xed and stained, and similarly of limited use. Based on the remaining specimens, it is di cult to see how Yamaguti (1937) arrived at his description unless the material has deteriorated with age. Features which appear distinctive are: the marginal valve which, although folded in the material, is indented at each hooklet (®gure 16B); the lobes of the marginal valve between hooklets are mostly large and are larger and wider anteriorly (®gure 16B); the penis is broad for the proximal one-third to two-thirds of its length (®gure 18); the distal portion of the vagina is cup-shaped and conspicuous (®gure 18); there is evidence of a lobe near the common genital pore (®gure 18); glands of Goto are visible; the anterior hamuli overlap half the length of the posterior hamuli (®gure 16B). In Yamaguti’s specimens, the proximal ends of the anterior hamuli overlap the proximal tips of the accessory sclerites.

There are, however, some errors in Yamaguti’ s (1937) description. He described the vas deferens and the duct from the accessory gland reservoir as joining near the base of the male copulatory organ whereas his specimens show that these ducts remain separate almost for the entire length of the organ (®gure 18). Yamaguti also described lateral alae on the accessory sclerites but we did not observe them. Furthermore, the ®gures of the anterior and posterior hamuli drawn by Yamaguti for B. epinepheli are not representative because of the orientation at which they were drawn. The anterior hamuli have a curved distal hook (®gure 19E) compared with Yamaguti’ s representation and the posterior hamuli have a wider root and are more strongly hooked distally (®gure 19F) than shown by Yamaguti.

We have also studied specimens identi®ed as B. epinepheli by Ogawa et al. (1995). Two specimens were from an unspeci®ed host from Shimonoseki Aquarium, Yamaguchi Prefecture. They were identi®ed originally by Tsutsumi and Ito (1965) as Benedenia sp. although they mentioned that the species was`highly similar’ to B. epinepheli . Tsutsumi and Ito recorded their specimens from six species of wild-caught ®shes in two families and on three species of ®shes from three families in experimental infections. Six other parasite specimens were studied from the body surface and ®ns of Paralichthys olivaceus (Paralichthyidae) from Yonouza, Oita Prefecture which were collected and identi®ed by Ogawa et al. (1995) as B. epinepheli . Ogawa et al. (1995) made comparisons with the specimens of B. epinepheli of Yamaguti (1937), Tsutsumi and Ito (1965) and with the holotype of B. congeri from Conger myriaster (Congridae) (see Yamaguti, 1958) and with reference material of B. congeri from Alutera monoceros (L.) ( Monacanthidae ) (see Kamegai et al., 1985). They concluded that all of these specimens are B. epinepheli . Our study of the same material leads us to agree with their conclusions, although the proximal ends of the anterior hamuli of these specimens do not overlap the proximal tips of the accessory sclerites.

The material of B. epinepheli deposited by Ogawa et al. (1995) has enabled several features of the anatomy to be clari®ed. The arrangement of the number of lobes in relation to the haptoral hooklets is: one lobe between hooklets of pair II; one lobe between hooklets II and the position of the distal tips of the posterior hamuli; one lobe between posterior hamuli and hooklet III; one larger lobe between each of hooklets III and IV, IV and V, V and VI, VI and VII, and VII and VIII with the more anterior lobes being much larger and wider (®gure 16B) and possibly comprising several smaller, fused lobes. The path of tendons is shown in ®gure 16B. In the female system, an internal fertilization chamber is present in the germarium and the distal portion of the vagina has a distinctive cup-shaped end provided with a narrow section immediately posteriorly which is equipped with a sphincter (®gure 18). In the male system, the vas deferens swells within the penis towards the distal one-third to one-half of the organ (®gure 18). Furthermore, the penis is strongly muscular and characteristically swollen in the proximal two-thirds of its length (®gure 18). The accessory gland reservoir is weakly muscular, proximal to the penis and there is no muscular penis sac (®gure 18). Ogawa et al. (1995) reported two ¯aps associated with the genital openings. One ¯ap is prominent, anteriorly directed and is associated with the common genital pore and a second, smaller ¯ap originates just posterior to the vaginal pore and extends anteriorly and parallel to the terminal portion of the vagina (®gure 18).

There is considerable morphological variation in the haptoral sclerites among individual specimens in the new material collected by Ogawa et al. (1995). In some of Ogawa’ s specimens, the proximal ends of the anterior hamuli overlap the proximal tips of the accessory sclerites, while in others there is no overlap. This appears to result from proportional variation in the morphology of the sclerites including, in some specimens, the absence of the accessory sclerites and reduced development of the anterior and posterior hamuli in others ( Ogawa et al., 1995).

Type-host and locality. Epinephelus akaara (Serranidae) , Tarumi, Inland Sea, Japan.

Published record and descriptions. Yamaguti (1937); Yamaguti (1958); Tsutsumi and Ito (1965); Kamegai et al. (1985); Ogawa et al. (1995).

Published host records. Anguilliformes : Congridae : Conger myriaster (see Yamaguti, 1958); Perciformes : Chaetodontidae : Chaetodon auriga (ForsskaÊl) (see Ogawa et al., 1995); Cheilodactylidae : Goniistius zonatus (Cuvier) (see Tsutsumi and Ito, 1965); Echeneidae : Echeneis naucrates (L.) (see Tsutsumi and Ito, 1965); Labridae : Semicossyphus reticulatus (see Tsutsumi and Ito, 1965); Oplegnathidae : Oplegnathus punctatus (Kroyer) (see Ogawa et al., 1995); Serranidae : Epinephelus akaara (see Yamaguti, 1937; Ogawa et al., 1995) [type host], E. moara (Temminck and Schlegel) (see Ogawa et al., 1995), E. septemfasciatus Thunberg (see Ogawa et al., 1995), E. suillus (Valenciennes in Cuvier and Valenciennes) (see Ogawa et al., 1995); Pleuronectiformes : Pleuronectidae : Paralichthys olivaceus (see Ogawa et al., 1995); Scorpaeniformes : Scorpaenidae : Pterois volitans (L.) (see Ogawa et al., 1995); Sebasticus marmoratus (Cuvier in Cuvier and Valenciennes) (see Ogawa et al., 1995); Sebastes schlegelii (Hilgendorf) (see Ogawa et al., 1995); Tetraodontiformes : Balistidae : Balistidoides conspicillus (probably B. conspicillum Bloch and Schneider ) (see Ogawa et al., 1995); Diodontidae : Diodon holocanthus (probably D. holacanthus L.) (see Ogawa et al., 1995); Monacanthidae : Aluterus monoceros (L.) (see Kamegai et al., 1985); Ostracidae: Ostracion tuberculatus (L.) (5 O. cubicus L., see Dor, 1984) (see Tsutsumi and Ito, 1965; Ogawa et al., 1995), O. immaculatus (Temminck and Schlegel) (see Tsutsumi and Ito, 1965; Ogawa et al., 1995); Tetraodontidae : Takifugu pardalis (Temminck and Schlegel) (see Tsutsumi and Ito, 1965); T. porphyreus (Temminck and Schlegel) (see Tsutsumi and Ito, 1965); T. poecilonotus (Temminck and Schlegel) (see Tsutsumi and Ito, 1965); T. niphobles ( Jordan and Snyder) (see Tsutsumi and Ito, 1965); T. radiatus (Temminck and Schlegel) (see Tsutsumi and Ito, 1965); T. vermicularis (Temminck and Schlegel) (see Tsutsumi and Ito, 1965).

Site . Gills ( Yamaguti, 1937; Yamaguti, 1958; Tsutsumi and Ito, 1965); body surfaces ( Tsutsumi and Ito, 1965); eyes ( Kamegai et al., 1985; Ogawa et al., 1995)`mouth’ ( Ogawa et al., 1995); ®ns ( Kamegai et al., 1985; Ogawa et al., 1995).

Distribution. Japan: Inland Sea ( Yamaguti, 1937, 1958); Hibiki-nada (Tsustumi and Ito, 1965); Nagasaki Prefecture ( Kamegai et al., 1985); Ehime, Hyogo, Oita and Shimane Prefectures, Tokyo Aquarium ( Ogawa et al., 1995).

Remarks. Ogawa et al. (1995) have removed a problematic species, B. congeri , from the genus and we concur that this species is synonymous with B. epinepheli . The anatomy of B. epinepheli is better understood and the species can be distinguished from others in the genus. Benedenia epinepheli has strongly recurved and relatively broad anterior and posterior hamuli, a strongly muscular penis which is swollen in the proximal two-thirds of its length, possesses a conspicuous, anteriorly directed lobe associated with the common genital pore and a smaller lobe in association with the vaginal pore. Furthermore, the terminal part of the vagina is cup-shaped and just posterior to this, there is a sphincter.

Benedenia epinepheli is known from 25 host species in 14 families and ®ve orders. Like Neobenedenia melleni ( MacCallum, 1927) Yamaguti, 1963 (see Whittington and Horton, 1996) and B. hawaiiensis (see below), B. epinepheli has very low hostspeci®city in arti®cial con®nement and has been recorded from the wild only on Epinephelus akaara and Conger myriaster . Yamaguti (1937) originally described the species from E. akaara in the Inland Sea of Japan and observations on more specimens from the type locality are desirable. Outbreaks have been recorded in aquaculture on at least six species of ®sh and on 18 species in aquaria. Many of the abnormalities observed by Ogawa et al. (1995) in B. epinepheli may be caused by the high population densities of parasites and the range of unusual hosts exposed arti®cially in con®nement which may alter infection success by larvae and contribute to a breakdown in host-speci®city. Species that display low host-speci®city such as B. epinepheli may prove valuable as models to investigate the phenomenon of host-induced morphological variation in monogeneans.