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aqua International Journal 6(2)



Volume 6, Issue 2 – November 2002

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Volume 6, Issue 2 – November 2002

Gerald R. Allen: Description of two new species of damselfishes (Pomacentridae: Pomacentrus) from Madagascar, pp. 45-52


Two new species of pomacentrid fishes are described from north-western Madagascar, based on specimens collected during a Conservation International coral reef survey in January 2002. Pomacentrus atriaxillaris is described from three specimens 25.4-64.0 mm SL, collected in areas where the bottom is sand-rubble, at depths of 10-27 m. It is related to P. reidi Fowler & Bean from the Philippines, eastern Indonesia, Papua New Guinea, Palau, Solomon Islands, Vanuatu, and the northern Great Barrier Reef, Australia. P. atriaxillaris is readily distinguished by the relatively large black spot at the upper pectoral fin base and particularly by the black coloration of the pectoral fin axil, as well as having a more angular posterior dorsal and anal fin profile. Pomacentrus caeruleopunctatus is described from four specimens, 62.0-72.9 mm SL, collected in areas of mixed live coral and rubble at depths of between 7-10 m. It is most similar to P. caeruleus Quoy & Gaimard, which is widely distributed in the western Indian Ocean. The two species differ in colour pattern details, body depth (P. caeruleus is more slender), and the greater maximum size of P. caeruleopunctatus.

Marta S. C. Soares, João Pedro Barreiros, Luis Sousa & Ricardo S. Santos: Agonistic and predatory behaviour of the lizardfish Synodus saurus (Linnaeus, 1758) (Actinopterygii: Synodontidae) from the Azores, pp. 53-60


The behaviour of the lizardfish Synodus saurus, a common demersal predator in Azorean waters, is described. A total of 25 hours’ qualitative diurnal underwater observations were carried out between July 2000 and January 2001. Behavioural aspects are presented, illustrated with diagrams based on in situ observations. S. saurus is a cryptic predator that feeds mainly of small pelagic, gregarious fish; it is primarily associated with soft bottom substrate. Besides remaining camouflaged buried beneath the sand, S. saurus is a highly mobile predator capable of rapidly swimming more than five meters to capture its prey. S. saurus maintains a territory through agonistic interactions, and also interacts non-agonistically with heterospecifics such as Bothus podas maderensis.

Ivan Sazima: Juvenile grunt (Haemulidae) mimicking a venomous leatherjacket (Carangidae), with a summary of Batesian mimicry in marine fishes, pp. 61-68


A presumed example of facultative Batesian mimicry between a grunt and a leatherjacket is described from tidal streams and mangrove zones in south-eastern Brazil. While moving over open areas or when threatened, juvenile Pomadasys ramosus (Haemulidae) closely resemble, and behave like, their presumed venomous model, juvenile Oligoplites palometa (Carangidae), a species with venom glands in its dorsal and anal spines. A summary of 24 published examples of Batesian mimicry in marine fishes shows that most species (83.3%) mimic venomous models, three species (12.5%) imitate poisonous models and only one species (4.1%) mimics a model which is neither venomous nor poisonous.

Amalia M. Miquelarena, Lucila C. Protogino, Ramiro Filiberto, and Hugo L. López: A new species of Bryconamericus (Characiformes: Characidae) from the Cuña-Pirú creek in north-eastern Argentina, with comments on accompanying fishes, pp. 69-82


A new species of the characid genus Bryconamericus is described from a tributary of the upper Paraná River, in the province of Misiones, Argentina. The new species can be distinguished from all other species of the genus by the presence of an irregular series of tricuspid teeth on the outer premaxillary row; branched anal fin rays 16-19; perforated scales on lateral line 37-40; a different coloration pattern, with a wide, silvery lateral band and a vertically-elongated humeral spot; very weak sexual dimorphism and the absence of bony hooks on fins in males. A list of fish incidentally collected with the new species is also included.

Wilson J. E. M. Costa and Morevy M. Cheffe: Austrolebias jaegari (Cyprinodontiformes: Rivulidae: Cynolebiatinae): a new annual fish from the Laguna dos Patos system, southern Brazil, with a redecription of A. gymnoventris (Amato), pp. 83-88


Austrolebias jaegari n. sp. from Pelotas, southern Brazil, is described, and A. gymnoventris (Amato) from Rocha, eastern Uruguay, is redescribed; both species share four synapomorphies: absence of scales on venter, body contact organs of male restricted to anteroventral portion of body side, absence of suborbital and supraorbital dark bars in live specimens, and a unique colour pattern on male body side. Austrolebias jaegari differs from A. gymnoventris by possessing a longer pectoral fin and, in the male, having contact organs on pectoral fin, a more anteriorly positioned anal fin origin, and narrower body bars.

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