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Volume 6, Issue 2, November 2002

Volume 6, Issue 2 – November 2002

06-2

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

Abstract

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.

Abstract | Full Text | PDF (104 KB)

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Pomacentrus reidi, about 70.0 mm SL, Rabaul, New Britain. Photo by G. R. Allen

 

 


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

Abstract

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.

Abstract | Full Text | PDF (124 KB)

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Predatory movement (type a)

 

 


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

Resumo

Um presumível exemplo de mimetismo Batesiano facultativo, entre uma espécie de corcoroca e uma espécie de guaivira, é descrito de manguezais no sudeste do Brasil. O juvenil de Pomadasys ramosus (Haemulidae), quando se desloca por áreas abertas ou quando ameaçado, apresenta grande semelhança de colorido e comportamento com o seu presumido modelo peçonhento, o juvenil de Oligoplites palometa (Carangidae), uma espécie com glândulas de peçonha em seus acúleos dorsais e anais. Um sumário de 24 casos publicados sobre mimetismo Batesiano entre peixes marinhos mostra que a maioria das espécies (83.3%) imita modelos peçonhentos, três espécies (12.5%) imitam modelos venenosos e apenas uma espécie (4.1%) imita um modelo que não é peçonhento nem venenoso.

Abstract | Full Text | PDF (88 KB)

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Pomadasys ramosus a larger juvenile (22.4 mm SL, ZUEC 5537) showing the dark, camouflaged, colour pattern while hovering close to plant debris (photographed in field aquarium). Photos by I. Sazima

 

 

 

 

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

Abstract

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.

Abstract | Full Text | PDF (200 KB)

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Bryconamericus mennii, n.sp., ILPLA 1251. Holotype male, 46.6 mm SL

 

 

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

Resumo

Austrolebias jaegari n. sp. de Pelotas, sul do Brasil, é descrita, e A. gymnoventris (Amato) de Rocha, leste do Uruguai, é redescrita; ambas espécies compartilham quatro sinapomorfias: ausência de escamas em ventre, órgãos de contato de macho restritos à porção anteroventral de lado de corpo, ausência de barra escura suborbital e supraorbital em exemplares vivos, e um padrão de colorido exclusivo em lado de corpo de macho. Austrolebias jaegari difere de A. gymnoventris por possuir nadadeira peitoral mais longa e macho ter órgãos de contato em nadadeira peitoral, origem de nadadeira anal mais anteriormente posicionada e barras de corpo mais estreitas.

Abstract | Full Text | PDF (100 KB)

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Austrolebias jaegari, UFRJ 5430, male, paratype, 28.4 mm SL; Brazil: Rio Grande do Sul: Pelotas. Photo by N. Jaegar

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