Molecular systematics of pinniped hookworms (Nematoda: Uncinaria): species delimitation, host associations and host-induced morphometric variation.

Hookworms of the genus Uncinaria have been widely reported from juvenile pinnipeds, however investigations of their systematics has been limited, with only two species described, Uncinaria lucasi from northern fur seals (Callorhinus ursinus) and Uncinaria hamiltoni from South American sea lions (Otaria flavescens). Hookworms were sampled from these hosts and seven additional species including Steller sea lions (Eumetopias jubatus), California sea lions (Zalophus californianus), South American fur seals (Arctocephalus australis), Australian fur seals (Arctocephalus pusillus), New Zealand sea lions (Phocarctos hookeri), southern elephant seals (Mirounga leonina), and the Mediterranean monk seal (Monachus monachus). One hundred and thirteen individual hookworms, including an outgroup species, were sequenced for four genes representing two loci (nuclear ribosomal DNA and mitochondrial DNA). Phylogenetic analyses of these sequences recovered seven independent evolutionary lineages or species, including the described species and five undescribed species. The molecular evidence shows that U. lucasi parasitises both C. ursinus and E. jubatus, whereas U. hamiltoni parasitises O. flavescens and A. australis. The five undescribed hookworm species were each associated with single host species (Z. californianus, A. pusillus, P. hookeri, M. leonina and M. monachus). For parasites of otarids, patterns of Uncinaria host-sharing and phylogenetic relationships had a strong biogeographic component with separate clades of parasites from northern versus southern hemisphere hosts. Comparison of phylogenies for these hookworms and their hosts suggests that the association of U. lucasi with northern fur seals results from a host-switch from Steller sea lions. Morphometric data for U. lucasi shows marked host-associated size differences for both sexes, with U. lucasi individuals from E. jubatus significantly larger. This result suggests that adult growth of U. lucasi is reduced within the host species representing the more recent host-parasite association. Intraspecific host-induced size differences are inconsistent with the exclusive use of morphometrics to delimit and diagnose species of Uncinaria from pinnipeds.

Cestodes from Hector's beaked whale ( Mesoplodon hectori ) and spectacled porpoise ( Phocoena dioptrica ) from Argentinean waters.

Single individuals of 2 little-known cetacean species, Mesoplodon hectori and Phocoena dioptrica , stranded and died on the coast of Argentina (Buenos Aires and Chubut provinces, respectively) and were studied for the presence of helminths. The cestodes found were described and illustrated using light microscopy. The following cestode taxa were recovered: Tetrabothrius ( Tetrabothrius ) hobergi n. sp. (several fragmented specimens, at least 1 gravid) and Tetrabothrius ( s.l. ) sp. 1 (several fragmented immature specimens) from M. hectori , and Tetrabothrius ( s.l. ) sp. 2 (single fragmented immature specimen) and 2 morphotypes of tetraphyllidean larvae from P. dioptrica. Tetrabothrius ( T. ) hobergi n. sp. can be distinguished from Tetrabothrius ( T. ) forsteri by the greater number of testes and larger eggs and oncospheres, from Tetrabothrius ( T. ) curilensis by the smaller testes and vitellarium, the shape and size of the ovary, and the larger oncospheres and longer embryonic hooks, and from Tetrabothrius ( T. ) sp. from Ziphius cavirostris by the narrower strobila, smaller scolex, and smaller number of testes. The generic designations of Tetrabothrius ( s.l. ) sp. 1 and Tetrabothrius ( s.l. ) sp. 2 were based on the scolex morphology. Tetrabothrius ( s.l. ) sp. 1 is closest to Tetrabothrius ( T. ) forsteri and Tetrabothrius ( Biamniculus ) innominatus based on the number of testes, while the scolex size of Tetrabothrius ( Tetrabothrius ) sp. 2 is within the variability range reported for Tetrabothrius ( T. ) forsteri . More definite identification of the 2 species was not possible due to the condition of the available material. The present study provides the first descriptions of cestodes from M. hectori and P. dioptrica , thus enriching the knowledge regarding the helminths of insufficiently studied marine mammals.

Parasites in stranded cetaceans of Patagonia.

There is an increasing interest in parasites of marine mammals of Argentina. Here, we examined several poorly known cetaceans, i.e., 2 spectacled porpoises and 1 Burmeister's porpoise (Phocoenidae), and 1 Gray's beaked whale and 1 Cuvier's beaked whale (Ziphidae); we also updated the parasite information for 1 sperm whale (Physeteridae). These hosts strand only occasionally. We found Anisakis simplex s.l. in 2 spectacled porpoises and the Burmeister's porpoise, and recorded its distribution among the stomach chambers. Anisakis physeteris infected the sperm whale; Corynosoma cetaceum occurred in the duodenal ampulla of the Burmeister's porpoise; Corynosoma australe was found in the posterior-most region of the intestine of 1 spectacled porpoise, while another one had Tetrabothrius sp. in the anal crypts; Corynosoma bullosum and Corynosoma sp. were found in the sperm whale. The only digenean found was Pholeter gastrophilus in the Burmeister's porpoise. Merocercoids of Phyllobothrium delphini were present in the blubber of 1 spectacled porpoise, the sperm whale, and the Gray's beaked whale, while Scolex pleuronectis infected the Gray's beaked whale and 1 spectacled porpoise. No parasites were recovered from the Cuvier's beaked whale. Poor parasite-species assemblages are consistent in marine mammals of Patagonia. Given the conservation status of these hosts, the limited parasitological information gathered is valuable for conservation or management of these hosts in Patagonia.

Parasite communities of common dolphins (Delphinus delphis) from Patagonia: the relation with host distribution and diet and comparison with sympatric hosts.

We studied the helminths of 18 common dolphins, Delphinus delphis, from northern Patagonia. Parasites were found only in the gastrointestinal tract. Four species were in the stomach, the nematode Anisakis simplex, the acanthocephalan Corynosoma cetaceum, and the digeneans Braunina cordiformis and Pholeter gastrophilus, plus 1 digenean in the hepatopancreatic ducts, Oschmarinella rochebruni. Infection levels were low (0-155 parasites). Braunina cordiformis and C. cetaceum were the most prevalent species. Anisakis simplex was mainly concentrated in the forestomach, B. cordiformis in the main stomach, and C. cetaceum in the pyloric stomach. Component diversity was low and component evenness was intermediate. Infracommunity diversity was also low, and the mean evenness was higher than at the component community level. Low prevalence in common dolphins is consistent with parasite assemblages of other cetaceans off Patagonia. None of the parasites found is specific to this host species within the study area. We suggest that potential prey are probably important in parasite transmission in this and other dolphins from the Patagonian region.

Uterine adenocarcinoma with generalised metastasis in a bottlenose dolphin Tursiops truncatus from northern Patagonia, Argentina.

An endometrial adenocarcinoma with areas of squamous differentiation and generalised metastasis was observed in a bottlenose dolphin Tursiops truncatus stranded in northern Patagonia in July 1997. This is the second report of a uterine adenocarcinoma in a free-living cetacean and the first in a Delphinidae. This neoplasm likely compromised reproduction for several years. In addition, the dolphin presented tattoo-like skin lesions and its digestive tract was infested by Anisakis simplex, Pseudoterranova sp., Braunina cordiformis and Corynosoma australe.