4/10/2023 0 Comments Candoll and talismaniaHowever, we do regard the presence of rostral ossicles as a putative character of elopomorphs, and it is included in our morphological data matrix ( Appendix 2, character 10). Until more extensive studies of the ontogeny of a variety of eels have been carried out, the generality of rostral ossicles and the association of the sensory canal with the premaxillae cannot be assessed. Most eels do not have an ethmoid commissure, but equally they have highly consolidated snouts that are usually regarded as resulting from a fusion between the mes-ethmoid and the vomer (the ethmovomer) and, de-batably, the premaxillae. Those eels (e.g., Anguilla) that have retained the ethmoid commissure and the premaxillae (fused with the ethmoid in the adult) have no separate rostral ossicles. In albuloids the canal pierces the premaxilla for part of its traverse across the snout, and this is presumed to have resulted from the fusion of rostral ossicles with the underlying premaxilla. The rostral ossicles surround the sensory canal as it passes from the bone-enclosed ethmoid commissure to the infraorbital sensory canal. However, the first three of these characters are not universal among elopomorphs but are restricted to the presumed plesiomorphic members (elopiforms, albuloids, and notacanthiforms). (1966) and Smith (1984), we regard the leptocephalus as a specialized larva ( Forey, 1973a,b) characterized by a leaf or ribbon shape, a gut which runs at the ventral mid-line to open just in front of the tail, and a body filled mostly by a mucinous pouch resorbed at metamorphosis during which there is marked shrinkage of the body and considerable change in fin positions and, especially, the anus.įour additional elopomorph characters have been proposed ( Forey, 1973a,b Jamieson, 1991): presence of prenasal and rostral ossicles, presence of a pectoral splint, fusion between the angular and retroarticular bones within the lower jaw ( Nelson, 1973), and sperm morphology. 1 Some authors have disputed that the leptocephalus is a derived feature of elopomorphs, preferring instead to regard it as the generalized teleost larval condition ( Harrison, 1966 Nybelin, 1971 Hulet and Robins, 1989). (1966) united them in the superorder Elopomorpha based on the fact that representatives of all subgroups have a leptocephalus larva. These fishes were widely scattered in teleost classifications until Greenwood et al. This also provides us with the opportunity to assess the relative contributions of these different types of data to a classification of elopomorphs.Įlopomorph fishes include tenpounders (Elops), Megalops, eels, the deep sea halosaurs and notacanths, and the highly derived but poorly-known gulper eels (saccopharyngoids). The purpose of this chapter is to evaluate the different theories of elopomorph interrelationship by examining a cladistic analysis of morphological data and by adding molecular data which has become available through the work of P.R. Four theories of interrelationships among elopomorph fishes, (a) Nelson (1973), Greenwood (1977) (b) Forey (1973a) (c) Greenwood et al. Knemidocoptes pilae is most commonly seen as an infestation of the skin of the cere and feet but often causes similar crusty, perforated lesions in the epidermis surrounding the vent. that have been identified are more likely to be located in the intestine or respiratory tract. 64 Cryptosporidium baileyi, a small apicomplexan parasite of birds, often replicates in the cloaca and the bursa. The first report in a nondomestic avian species of cryptosporidiosis was by Doster et al in two red-lored Amazons (Amazona autumnalis). Urogonimus macrostomus is another digenic trematode that inhabits the cloaca of temperate passerine birds. 59, 60 The intermediate host is typically an ostracod.īrachylaimid trematodes (e.g., Tinamutrema canoae of tinamous) are frequently found in the cloaca and bursa of species that consume the snail, which is an intermediate host. This tapeworm lives primarily within the coprodeum. Michael Taylor, in Current Therapy in Avian Medicine and Surgery, 2016 Parasitic cloacitisĬloacotaenia megalops is a fairly common cestode with a worldwide occurrence in waterfowl and some marsh dwelling species.
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