On the functional morphology of a new fauna of Monogenoidea on fishes from Trivandrum and environs Part II. Opisthogynidae fam.nov. (Gastrocotyloidea) and Abortipedinae subfam.nov. (Protomicrocotyloidea)

Abstract

Opisthogynidae fam.nov. is erected for a group of Gastrocotyloidea Price (1959), in which the gastrocotylid clamps are limited to the four primary pairs, the ovarian field is posterior to the main testicular field, and the cuticle is finely plicated, producing forward-pointing serrations along the margins of the hind body. Opisthogyninae subfam.nov. have a slightly asymmetrical haptor due to unequal lengths of clamps and their pedicels, or to one row being sessile on glandular pads which may be confluent as a thick shelf on one side only. The clamps have an incipient internal asymmetry, the adaxial sector being the more developed. Opisthogyne keralae gen. et sp.nov., on Sphyraena acutipennis: with subequal clamps unequally pedunculated, retains the protohaptor with three pairs of anchors; the muscular penis opens in a lateral atrium, and the median dorsal vagina is unarmed. Gemmaecaputia corrugata Tripathi, 1959, and G. brinkmannii sp.nov., both on Sphyraena obtusata, have each a very conspicuous pre-oral gland-mass. They have unequally disposed and asymmetrical clamps on stalks but lack a protohaptor and anchors. The genital terminalis is similar. The genotype Gemmaecaputia corrugata is redescribed. The new species G. brinkmannii differs in having some post-ovarial testes, in the muscular penis being less heavily cuticularized and the egg being smaller; yet it is nearly twice the size of the genotype, and its pre-oral glands are in two groups of two rows, instead of a single continuous row. Both Allodiscocotyla chorinemi Yamag., 1953 and A. diacanthi sp.nov., occur on Chorinemus sanctipetri. In both of these, unlike the last two genera, the asymmetrical clamps have ribs in the walls. One row of clamps is sessile, on a shelf, or on separate pads, and the other is short-stalked. The protohaptor is retained by the adult. There is a median spiny eversible cirrus and a single lateral unarmed vagina. The genotype is redescribed from a new host. The new species differs in its four separate clamppads on one side, the opposite row being subsessile. There is only one pair of anchors (the largest) instead of three pairs; there are no par-ovarial testes (all are preovarial), and the internal details of the clamps differ. Pseudomazocraes Caballero & Bravo Hollis, 1955, is compared with and included in the Opisthogyninae. Pentatrinae subfam.nov. is erected for Pentatres sphyraenae Euzet & Razarihelisoa, 1959, since its gastrocotylid clamps are modified like those of Priceinae (Gastrocotylidae), but are internally symmetrical and disposed in an asymmetrical fringing-arc round the hind body; the three larger clamps are pedunculated. The muscular penis and atrium are sublateral. Vallisiinae Price, 1943, is emended to include only Vallisia and Vallisiopsis, with highly developed somatic asymmetry. Slight asymmetry is seen in the short-stalked clamps which are usually shifted backwards from the sessile row, the clamps of which are either near three marginal tabs separated by glandular clefts, or on four pads. The clamps themselves are symmetrical and gastrocotylid with ribs in the walls, but without extra effective sclerites. The protohaptor is broad and has one pair of anchors. In all there is a long median spiny eversible cirrus. Vallisia indica sp.nov. from Chorinemus sanctipetri, has sessile clamps on four separate pads and is nearest to Vallisia chorinemi Yamag. This latter, however, has three marginal tabs for the sessile clamps and the combs in the two lateral vaginae are different. V. indica has only half the number of testes and lacks oesophageal diverticula.Protomicrocotyloidea sup.fam.nov. is created and defined to include aberrant discocotyline forms in which the protohaptor is secondarily developed as a main holdfast. This is a transverse musculo-glandular organ retaining the three dissimilar pairs of larval anchors. The other main holdfast is the unique posteriorlateral glandular pit with projecting muscular lips, just anterior-dorsal to the relatively feeble clamps, which may be gastrocotylid or discocotylid, some always being inhibited. Carangixenus gen.nov. erected for Protomicrocotyle celebensis Yamag., 1953, shares Protomicrocotylinae with Protomicrocotyle mirabilis (MacCallum), since both have gastrocotylid clamps, but in the former they have additional sclerites and an asymmetry approaching that of Gotocotyla spp. (Gastrocotylidae). In Abortipedinae subfam.nov. the muscular protohaptor has anchor-like lobes at each end as in Protomicrocotylinae, but the four clamps on the uninhibited side of the euhaptor are simple discocotylid and without ribs in the capsule walls. The genital terminalia are similar, though the testes, always mainly pre-ovarial, are far more numerous. Abortipedia indica gen. et sp.nov., from the gills of Caranx hippos, differs from the second species Abortipedia pacifica (Meserve) comb.nov. in details of the clamps, in the lack of oesophageal diverticula, and in its uniquely convoluted ovary. The spines of the lateral genital atrium and penis, and those of the lateral vaginal plaque also, are different, and so are the hosts and geographical locations. Lethacotylinae subfam.nov. has been erected for Lethacotyle Manter & Prince, 1953, in which all the clamps are inhibited, and Bilateracotyle Chauhan, 1945, in which only the anterior pair of the four primary pairs is inhibited. In the latter, the clamps are simple and discocotylid. In both genera, the protohaptor is a large wide hemispherical musculo-glandular organ constricted off from the hind body, and is provided with a plicated cuticle, and bears the three characteristic pairs of anchors; and again in both genera, the posterior-lateral funnel-like organ is particularly prominent. The Protomicrocotyloidea are unique in the higher Monogenoidea in using parts of the body as holdfasts which therefore tend to be substitutes, functionally, for the clamps; they are unique with the doubtful exception of Osphyobothrus Yamag., 1958, in showing a secondary development of the protohaptor.I would like to thank, sincerely, Miss Nora G. Sproston for maintaining our correspondence and for the exchange of ideas on the present subject and particularly for her collaboration in the last section ‘Relationships of the Protomicrocotyloidea’; Dr N. K. Panikkar for providing facilities for my investigations at the Central Marine Fisheries Research Station, Mandapam Camp, and Dr C. C. John, for permission to collect material from the Marine Biological Laboratory of the University of Kerala, Trivandrum.