Vědecká prezentace v zoologii Zadání posteru: Velikost 80 cm (šířka) x 100 cm (výška) TWO REMARKABLE NEMATODES OF THE AFRICAN SNAKE FISH, ERPETOICHTHYS CALABARICUS, FROM NIGERIA JMÉNO autora (autorů) posteru Department of Zoology and Ecology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic Pokud si vymyslíte spoluautora s jinou adresou …. nezapomeňte k uvedenému jménu a adrese přidat odpovídající symbol/číslo INTRODUCTION The family Polypteridae (bichirs), confined to the freshwaters of tropical Africa, contains nine species of Polypterus Lacepède, 1803 and only one species of Erpetoichthys Smith, 1865. Bichirs are popular aquarium fishes, and among them, E. calabaricus (snake fish or reedfish) is imported in particularly large quantities from the natural habitats of Nigeria. Whereas the species of Polypterus are already known to harbour 5 nematode species of 4 families (see Conclusion), the parasite fauna of E. calabaricus has not yet been studied. Presented in this study are the first records of two nematode species in this host. MATERIALS and METHODS Fish hosts (n = 2) of Erpetoichthys calabaricus (Fig. 1) were obtained from a pet store in the Czech Republic where they had been directly imported from Nigeria. Eight specimens of nematodes were removed from the intestine of the fish, fixed in 4 % formaldehyde and cleared with glycerine for light microscopy examination. A light microscope equipped with differential interference contrast (Nomarski DIC) and digital image analysis (Micro Image 4) were used for the morphometrical study. Drawings were made, using an Olympus microscope drawing attachment. RESULTS Batrachocamallanus siluranae Jackson et Tinsley, 1995 Description (one female specimen): Small, yellowish nematode; body length 3.50 mm, maximum width 0.17mm. Cuticle thick, with marked transverse striations. Orange-brown buccal capsule barrel-shaped; its inner surface smooth, outer surface with sclerotised granules different in size (Fig. 3). Oesophagus divided; anterior muscular portion claviform, about the same length as the glandular one. Deirids somewhat posterior to nerve ring. Vulva preequatorial, situated at 44 % of body length (Figs. 2C,4). Tail terminating in a crown of 5 mucrons (Fig 2D). Remarks Representatives of Batrachocamallanus Jackson et Tinsley, 1995 (Spirurida: Camallanidae) have so far only been described in aquatic clawed toads (Xenopus sp.) from Africa. The finding of a member of the genus in the freshwater polypterid fish may indicate an accidental infection acquired by E. calabaricus while feeding infected copepods, probable intermediate hosts of the parasite. Considering the subadult stage of the presented nematode specimen, E. calabaricus may well serve as a paradefinitive host of B. siluranae. Gendria polypteri Vassiliadès et Chevalier, 1973 Description (3 male, 4 female specimens): Small-sized, whitish to yellowish nematodes; cuticle with very fine transverse striations. Head surrounded by a distinct cephalic vesicle (Figs. 5A, 6). Oesophagus undivided, consisting of cylindrical anterior muscular portion and longer posterior muscular-glandular portion (Fig. 5A). Male: Body length 2.78 – 2.92 mm, maximum width 0.15 – 0.17 mm. Precloacal sucker well developed; twelve paired and one unpaired caudal papillae present; caudal alae absent (Fig.5E). Spicules equal, 0.12 – 0.15 mm long (Fig. 5F). Female: Body length 2.50 – 3.67 mm. Vulva postequatorial, situated at 57.20 - 71.42 % of body length; vulvar lips slightly elevated; uteri opposed. Remarks The genus Gendria Baylis, 1930 (Ascaridida, Quimperiidae) includes six species parasitizing freshwater fishes and amphibians. Three species occur in hosts with African distribution, two of them are parasitic in fishes only: G. Tilapiae Baylis, 1930 in Tilapia galilaea (Cichlidae) and G. polypteri in Polypterus senegalus (Polypteridae). The morphology of specimens from E. calabaricus is more or less identical with that described for G. polypteri by Vassiliadès et Chevalier (1973). CONCLUSION Fishes of Polypteridae are so far known to host 5 nematode species: Camallanus polypteri Kabré et Petter, 1997 from the Nile bichir (P. bichir Lacepède, 1803); Amplicaecum sp. (larva, type I) and Spirocamallanus spiralis (Baylis, 1923) from the saddled bichir (P. endlicheri Heckel, 1847); and Amplicaecum sp. (larva, type I), Gendria polypteri Vassiliadès et Chevalier, 1973 and Rhabdochona congolensis Campana-Rouget, 1961 from the grey bichir (P. senegalus Cuvier, 1829). The present finding of G. polypteri in Erpetoichthys calabaricus represents a new host record as well as the first record of this parasite from Nigeria. As to the finding of Batrachocamallanus siluranae, currently a parasite of clawed toads, E. calabaricus may well serve as a paradefinitive host of the nematode species, which cannot attain gravidity in fishes. ACKNOWLEDGEMENTS This study was supported by the Grant Agency of Academy of Sciences of the Czech Republic, grant No IAA 6093404 and grant No 524/03/0061. Figure Captions (popisky k obrázkům) Figure 1 Erpetoichthys calabaricus Smith, 1865 Family: Polypteridae (Bichirs) Order: Polypteriformes Class: Actinopterygii (ray-finned fishes) Distribution: Africa - Ogun River mouth in Nigeria to Chiloango River in Congo Importance: aquarium Figure 2 Batrachocamallanus siluranae female from reedfish, Erpetoichthys calabaricus. A – anterior part of body; B – cephalic end; C – region of vulva; D – posterior end, lateral view. Scale bars in mm. Figure 3 Photomicrograph of buccal capsule covered with sclerotised granules. Scale bar = 50 mm. Figure 4 Photomicrograph of vulva; anterior lip provided with prominent rugose cuticular process directed posteriorly. Scale bar = 50 mm. Figure 5 Gendria polypteri Vassiliadès et Chevalier, 1973. A – anterior part of female, lateral view; B – posterior end of female, lateroventral view; C – region of vulva; D – egg; E – posterior end of male, lateral view; F – spicules. Scale bars in mm. Figure 6 Photomicrograph of cephalic vesicle. Scale bar = 50 mm. Figure 7 Photomicrograph of spicule supported with slightly sclerotised wing-shaped sheath. Scale bar = 100 mm.