Three new species of Cichlidogyrus Paperna, 1960 (Monogenea, Ancyrocephalidae) parasitic on Tylochromis jentinki (Steindachner, 1895) (Pisces, Cichlidae) in West Africa

Trois monogènes nouveaux : #Cichlidogyrus berrebii n. sp., #C. pouyaudi n. sp. et #C. kothiasi n. sp., parasites branchiaux de #Tylochromis jentini (Cichlidae), sont décrits en Afrique de l'Ouest (Côte d'Ivoire et Guinée). Ces trois nouvelles espèces sont considérées comme primitives à cause de la morphologie caractéristique de la barre transversale dorsale du hapteur, mais elles sont cependant situées dans le genre #Cichlidogyrus$. (Résumé d'auteur

Cichlidogyrus Paperna, 1960 (Monogenea, Ancyrocephalidae) : gill parasites from West African Cichlidae of the subgenus Coptodon Regan, 1920 (Pisces), with descriptions of six new species

Une étude des parasites branchiaux de poissons appartenant au sous-genre #Coptodon Regan, 1920 (#Cichlidae) : #Tilapia coffea Thys van den Audenaerde ; #T. dageti Thys van den Audenaerde ; #T. guineensis (Bleecker) ; #T. louka Thys van den Audenaerde ; #T. walteri Thys van den Audenaerde ; and #T. zillii (Gervais) ; provenant de différentes localités en Afrique de l'Ouest (Burkina Faso, Congo, Côte d'Ivoire, Guinée, Mali et Sénégal) a révélé la présence de 19 espèces du genre #Cichlidogyrus Paperna, 1960 (#Monogenea, #Ancyrocephalidae). Six sont considérées comme nouvelles : #C. amphoratus n. sp., #C. levequei n. sp., #C. microscutus n. sp., #C. ornatus n. sp., #C. ouedraogoi n. sp. et #C. yanni$ n. sp. Nous discutons de la spécificité de ces parasites. (Résumé d'auteur

Can host body size explain the parasite species richness in tropical freshwater fishes ?

The variability of monogenean gill ectoparasite species richness in 19 West African cyprinid species was analyzed using the following seven predictor variables : host size, number of drainage basins, number of sympatric cyprinid species, host diversity, association with mainland forest, host ecology, and monogenean biological labelling. The size of the host species accounted for 77% of the variation in the number of parasite species per host, and host ecology and additional 8%. Together the effects of host size and host ecology accounted for 85% of the variation in monogenean species richness. This study shows that the deciding factors for explaining monogenean species richness in West African cyprinid fishes are host species size and host ecology. These results were compared with main factors responsible for parasite species richness in fish communities. Other possible explanations of monogenean community structure in West African cyprinids are discussed. (Résumé d'auteur

Experimental infections, using a fluorescent marker, of two elasmobranch species by unciliated larvae of Branchotenthes octohamatus (Monogenea: Hexabothriidae): invasion route, host specificity and post-larval development

The infection biology of Branchotenthes octohamatus (Monogenea: Hexabothriidae) from the gills of the southern fiddler ray, Trygonorrhina fasciata (Rhinobatidae), was studied using the fluorescent dye, 5(6)-carboxyfluorescein diacetate N-succinimidyl ester (CFSE). This is the first use of this technique on a monogenean species with unciliated larvae and the first for any monogenean larva infecting an elasmobranch host. CFSE-labelled post-larvae were recovered from gills of T. fasciata within 30 min of exposure to the host, providing strong evidence that larvae invade host gills directly and do not migrate after initial attachment elsewhere. The rapidity with which larvae settled suggests that the mode of infection may deliver larvae directly to the gills via the host's inhalant respiratory current. The specificity of B. octohamatus was investigated by exposing a sympatric rhinobatid host species, the western shovelnose ray, Aptychotrema vincentiana, to B. octohamatus larvae newly emerged from eggs laid by adult parasites from gills of T. fasciata. Experimental exposure of A. vincentiana to freshly hatched B. octohamatus larvae resulted in a persistent infection, indicating that B. octohamatus may not be strictly host specific. Post-larval development charted on these experimentally infected A. vincentiana specimens was slow. Parasites appeared to be sexually mature at 91 days at 21–25°C. Branchotenthes octohamatus larvae bear only 4 pairs of hooklets on the haptor whereas all other hexabothriid larvae described so far have 5 hooklet pairs. Ontogenetic changes to the haptor revealed that it is probably hooklet pair III that is lost from B. octohamatus prior to larval development.V. Glennon, L. A. Chisholm and I. D. Whittingto

Three unrelated species, 3 sites, same host monogenean parasites of the southern fiddler ray, Trygonorrhina fasciata, in South Australia: egg hatching strategies and larval behaviour

The southern fiddler ray, Trygonorrhina fasciata (Rhinobatidae), is parasitized by 3 monogenean (platyhelminth) species from 3 families on 3 different sites of the host: Calicotyle australis (Monocotylidae) from the cloaca, Pseudoleptobothrium aptychotremae (Microbothriidae) from the skin and Branchotenthes octohamatus (Hexabothriidae) from the gills. Cues that promote egg hatching were investigated for each species and the behaviour of their larvae was also documented. Eggs were laid by parasites in vivo and maintained at 22 °C. Three different egg hatching and host finding strategies were discovered. Calicotyle australis eggs hatched spontaneously with a strong diurnal rhythm that is likely to be under circadian control. The larva is ciliated, photo-responsive and can survive for up to 24 h at 22 °C after hatching. Pseudoleptobothrium aptychotremae may have a ‘bet-hedging’ strategy. Some eggs hatched spontaneously and rhythmically. However, since the hatching success was low, it is possible that other eggs require a different cue provided by the host. The larva is also ciliated but shows no photo-response and was observed to remain active for <4 h at 22 °C after hatching. Branchotenthes octohamatus has a ‘sit-and-wait’ strategy that depends on mechanical disturbance to stimulate hatching. The larva is unciliated, shows no photo-response but may survive for more than 2 days at 22 °C after hatching. The implications of hatching strategy, larval behaviour and morphology in the goal to find a host are discussed for each species.V. Glennon, L. A. Chisholm and I. D. Whittingto