Fellodistomidae NICOLL, 1909

Sey, O., Nahhas, F. M., Uch, S. & Vang, C., 2003, Digenetic Trematodes From Marine Fishes Off The Coast Of Kuwait, Arabian Gulf: Fellodistomidae And Some Smaller Families, New Host And Geographic Records, Acta Zoologica Academiae Scientiarum Hungaricae 49 (3), pp. 179-200 : 180-186

Family Fellodistomidae NICOLL, 1909

Lintonium vibex (LINTON, 1900) STUNKARD et NIGRELLI, 1930

( Figs 1 A-B)

Host: Lagocephalus lunaris (BLOCH et SCHNEIDER, 1801) ( Tetraodontidae )

Description based on three specimens from three hosts. Body plump, 2,750 –3,505 × 1,000 –1,125 at acetabular level (3,162 × 1,058); forebody 700–1,025 (883); hindbody 1,500 –1,975 (1,767). Tegument smooth, thick. Eyespot pigment absent. Oral sucker 270–380 × 290–430 (320 × 353). Ventral sucker 550–678 × 600–775 (608 × 683) with transverse opening, 60–69% (65%) of body width. Sucker ratio 1:1.79–1:2:05 (1:1.94). Prepharynx absent; pharynx 140–190 × 190–260 (167 × 217); oesophagus 50–150 (100) long; intestinal bifurcation near mid forebody; caeca blind, not reaching posterior end of body. Gonads in mid third of body. Testes symmetrical, chiefly intercaecal; right testis 190–270 × 130–230 (230 180); left testis 150–220 × 200–260 (180 × 230). Cirrus sac ovoid 240–290 × 70–150 (270 × 110), containing bipartite spherical or ovoid seminal vesicle 80–120 × 78–120 (100 98), posterior segment larger than anterior one; pars prostatica, 125–150 × 63–100 (137 × 65) ovoid to cylindrical; cirrus short. Ovary weakly trilobed, anterior to right testis, 180–200 x 200–210 (190 × 205); seminal receptacle absent; ootype, Mehlis’ complex and Laurer’s canal not seen; uterus filling all intercaecal space posterior to ovary; metraterm well-developed, extending sinistrally to ventral sucker, entering genital pore near intestinal bifurcation. Vitelline follicles extracaecal extending from near anterior level of ovary to near posterior end of caeca. Eggs numerous, 35 – 45 × 23–28 (40 × 26). Genital pore median, bifurcal or slightly prebifurcal. Excretory vesicle covered by uterus, canals extending to junction of pharynx and oral sucker..

Remarks. The genus Lintonium has a wide distribution having been reported from various parts of the world; this distribution, however, seems to be restricted to a group of hosts belonging chiefly to species of Spheroides , Tetraodon , Arothron ( Tetraodontidae ), Abalistes, Balistis ( Balistidae ), Cantherines , and Monacanthus ( Monacanthidae ). YAMAGUTI (1971) lists five species in the genus ( L. vibex

(LINTON, 1900) STUNKARD e t NIGRELLI, 1930, L. consors (LÜHE, 1906) CROWCROFT, 1950 , L. laymani, ( LAYMAN, 1930) SKRJABIN e t KOVAL, 1957, L. pulchrum (JOHNSTON, 1913) SKRJABIN e t KOVAL, 1957) and L. novikovi BAEVA, 1965 . Lintonium novikovi from Cololabis (Scomberesox) saira (BREVOORT) ( Scomberesocidae ) does not belong in the genus and is probably a new sclerodistomid genus according to YAMAGUTI (1971). LAYMAN (1930) reported Steringotrema pulchrum from Cantherines modestus in theSea of Japan. S KRJABIN and KOVAL (1957), transferred it to Lintonium and renamed it L. laymani . SKRJABIN and KOVAL (1957), MANTER and PRITCHARD (1962) and MADHAVI (1975) recognized four species in the genus Lintonium : L. vibex , L. consors , L. pulchrum and L.

laymani . In a key to the species, SKRJABIN and KOVAL (1957) distinguished L. laymani from the other three by an equatorial ventral sucker. MANTER and PRITCHARD (1962) reviewed the history of the four species and their characteristics and concluded that “ L. vibex ” of YAMAGUTI (1934) and CROWCROFT (1950) from Japan and Tasmania, respectively, are actually L. laymani . MADHAVI (1975) agreed with MANTER and PRITCHARD’ s (1962) conclusion. STUNKARD and NIGRELLI (1930) cited a 1928 reference by ODHNER that L. (Steringotrema) pulchrum is identical with L. (Gastris) consors ; CROWCROFT (1950) examined one of JOHNSTON’ s cotypes of Steringotrema pulchrum from the Australian Museum in Sidney and indicated that “a comparison of the illustrations of Gastris consors and Steringotrema pulchrum reveals differences in size and body proportions only” and “Odhner’s view is regarded as correct”. MACHIDA (1971) considered L. laymani a synonym of L. vibex . MADHAVI (1975) redescribed L. vibex of PARUKHIN and CHIKUNOVA, 1964 from Abalistes stellaris (BLOCH e t SCHNEIDER) ( Balistidae ) from South China Sea and renamed it L. pseudovibex . MADHAVI’ s redescription was based on three specimens from one of three Monacanthus choirocephalus BLEEKER ; She admitted, however, that “ L. pseudovibex shows characters that are intermediate between L. vibex and L. laymani ”. Lintonium puriensis GUPTA et AHMAD, 1977 was described from Tetraodon (Lagocephalus) lunaris from Orissa, Bay of Bengal; the latter shows characteristics intermediate between the various species. Two of his figures show two symmetrical testes, close together, intercaecal (as in L. consors and L. pulchrum ) thethird diagonal and further apart.

KISHORE et al. (1989) described the nervous system of L. pulchrum from Lagocephalus lunaris , but the species itself was not described. Body shape and egg size of L. vibex arevariable(Y AMAGUTI 1934, CROWCROFT 1950). Populations of “ L. vibex ” reported by the various investigators seem to fall into two egg size groups 45–59 × 23–28 and 26–42 × 13–24, the narrowest, 13–22 was cited by CROWCROFT (1950); YAMAGUTI (1934) listed 42–48 × 24–27 for his specimens.

MADHAVI (1975) suggested that Paradiplangus GUPTA, 1968 and Paradiplobulbus BILQEES, 1972 aresynonyms of Lintonium , a suggestion accepted by BRAY (2002). MADHAVI (1975) collected specimens from Gastrophysus (Lagocephalus) lunaris which she identified as L. pulchrum and indicated that GUPTA’ s specimens “agree in many respects” with her L. pulchrum .

At least one other species has been added to the genus, L. srivastavai LAMOTHE-ARGUMEDO, 1969 from theintestineof Spheroides annulatus (Jenyns) from Oaxaca, Mexico. LAMOTHE-ARGUMEDO (1969) distinguished his species, based on one specimen, from L. vibex by theround shapeof theovary, and from L. consors by well-separated testes, tubular seminal vesicle, uterine coils that extend extracaecally, two caeca of unequal length, and asymmetrical distribution of vitelline follicles, one group extending posterior to the right (longer) caecum, reaching almost to the posterior end of the body, the other group slightly posterior to the left shorter caecum.

Paradiplobulbus heterorchis and P. isorchis from Tetraodon (Lagocephalus) lunaris were described by BILQEES (1972) from theKarachi coast. P. heterorchis has a plump shape, symmetrical or subsymmetrical testes, symmetrical distribution of vitelline follicles, and eggs 30–35 × 28–30. P. isorchis was described as having a fusiform body, slightly oblique testes (her illustration shows definitely oblique testes), unequal distribution of vitelline follicles, and eggs 50 × 30. MADHAVI (1975) transferred the two species to Lintonium becoming L. heterorchis and L. isorchis . There is a great deal of confusion in the literature relating to all these species. Our review of the literature suggests that there are probably only two valid species L. vibex and L. consors which can bedistinguished from each other by the presence of an indentation posterior to the acetabulum, testes relatively closer to each other, relatively shorter caeca, and vitelline follicles that do not extend to the posterior end of the caeca compared with those of L. vibex . The figures of L. consors illustrated by MANTER and PRITCHARD (1962) and BRAY (2002) show some differences; they differ in the position of the ventral sucker, location of the gonads relative to the ventral sucker, and the anterior extent of the excretory canals (the ventral sucker in the anterior body third and not filling the entire body width, the gonads in the mid hindbody, and the excretory canals extending to the junction of the oral sucker and the pharynx compared with a ventral sucker occupying almost theentiremidbody width, thegonads near theventral sucker and the excretory canals reaching only to the posterior level of the pharynx in BRAY’ s illustration. Features common to both which characterize the species are the indentation posterior to the ventral sucker, and intercaecal testes that are close to each other.

Complexobursa vjetnamensis OSHMARIN et MAMAEV, 1963

( Figs 2 A-B)

Host: Terapon theraps (CUVIER, 1829) ( Teraponidae )

Description based on six specimens, measurements on one. Body elongate, 2,550 × 480 at ventral sucker; forebody 100; hindbody 2,175. Tegument smooth. Eyespot pigment absent. Oral sucker terminal, 80 × 83. Ventral sucker 200 × 190. Sucker ratio 1:2.38. Prepharynx 5; pharynx 50 × 48; oesophagus 100; intestinal bifurcation at about anterior level of cirrus sac; caeca blind, posterior extent covered by uterus. Testes in mid third of body, smooth, tandem; anterior testis 200 × 190; posterior testis 230 × 160; intertesticular space 50; posttesticular space 1200. Cirrus sac 350 × 179, containing bipartite seminal vesicle, proximal part small, spherical, distal part long, convoluted; pars prostatica long and wide, about two thirds length of distal segment of seminal vesicle; cirrus short. Ovary trilobed, 145 × 103, pretesticular, 170 from anterior level of anterior testis; anterior lobe near posterior level of cirrus sac; seminal receptacle absent; ootype-Mehlis’ complex, Laurer’s canal not seen; uterus filling all space posterior to posterior testis; metraterm well-developed, sinistral to ventral sucker, entering genital atrium near intestinal bifurcation. Genital atrium large, complex, containing globular structure with radiating fibers. Relationship of globular structure to terminal male and female components not clear. Genital pore median, bifurcal or slightly prebifurcal. Vitelline follicles extending from near anterior level of ovary to posterior end of body, confluent in ovario-testicular and intertesticular space. Eggs numerous, 35–45 × 23–28 (43 × 27). Excretory vesicle covered by uterus.

Remarks. Five of our specimens were in bad condition; although measurements are not reported, some information was obtained from them to enhance the description, especially that of the cirrus sac. The description and measurements agree well with those of OSHMARIN and MAMAEV (1963) from thesamehost spe - cies in Vietnam except, perhaps, in the interpretation of certain aspects of the cirrus sac. There is no reason for us, however, to conclude that we have a different species. BRAY (2002) examined specimens of C. vjetnamensis from Pelates quadrilineatus CUVIER ( Teraponidae ) from Moreton Bay, Australia. He gave a somewhat different interpretation of the terminal genitalia stating “There is a bipartite seminal vesicle, with the distal part much longer than the proximal, which leads into a long, recurved pars prostatica filled with anuclear cell-like bodies. The ejaculatory duct is short, narrow and inconspicuous but leads into a more or less hemispherical chamber, which has been considered the pars prostatica by earlier workers. This organ is prominent and filled with radiating fibers. I interpret this organ as an outgrowth of the genital atrium, the remainder of which has a completely wrinkled wall”. Our interpretation of the cirrus sac and its structures vesicle is similar to his, except for the pars prostatica which seems to be a straight and wide sac-like structure.

Figures

Fig. 1. A = Lintonium vibex (LINTON, 1900) STUNKARD e t NIGRELLI, 1930, from Lagocephalus lunaris. Ventral view. Scale 1 mm. B = Cirrus sac free-hand composite drawing

Fig. 2. A = Complexobursa vjetnamensis OSHMARIN e t MAMAEV, 1963, from Terapon theraps. Ventrolateral view. Scale 1 mm. B. Cirrus sac free-hand drawing