Richness and palaeo-zoogeographical significance of the benthic Ostracoda (Crustacea) from the oceanic Island of Trindade and Rocas Atoll, Brazil

Abstract

-Twenty-one ostracode species from Trindade Island and 23 species from Rocas Atoll are herein recorded. The collective fauna shows low richness and low abundance compared with other oceanic islands. Nevertheless, the presence of tropical pandemic species such as Kotarocythere inconspicua (Brady) and Triebelina sertata Triebel, of the almost exclusively Pacific genus Australimoosella, the Atlanto-Caribbean taxa such as Glyptobairdia coronata (Brady) and Caudites obliquecostatus Bold, together with species typical of the Brazilian shelf, reveals a mixed fauna likely influenced by dispersal of shallow-water taxa between seamounts during Quaternary sea-level lowstands. In contrast to other oceanic islands, endemic ostracode taxa are apparently absent in these two islands. Tenedocythere trindadensis sp. nov., a species also recorded on the Brazilian equatorial shelf, is described and illustrated.Key words: oceanic island, ostracodes, Rocas Atoll, Trindade Island, zoogeography, paleozoogeography.RESUMO -Foram registradas 21 espécies de ostracodes para a Ilha da Trindade e 23 para o Atol das Rocas. Ambas ostracofaunas mostram baixa riqueza e abundância de espécies quando comparadas com outras ilhas oceânicas. Contudo, a presença de espécies tropicais pandêmicas, como Kotarocythere inconspicua (Brady) e Triebelina sertata Triebel, do gênero Australimoosella que é quase exclusivo do Pacífico, e de táxons atlântico-caribenhos como Glyptobairdia coronata (Brady) e Caudites obliquecostatus Bold, juntamente com espécies típicas da plataforma brasileira, revela uma fauna mista provavelmente influenciada pela dispersão de táxons de águas rasas entre montes submarinos durante períodos de mar baixo ao longo do Quaternário. Contrastando com outras ilhas oceânicas, estas duas ilhas parecem não apresentar espécies endêmicas de ostracodes. Tenedocythere trindadensis sp. nov., uma espécie também registrada na plataforma equatorial do Brasil, é aqui descrita e ilustrada.Palavras-chave: ilhas oceânicas, ostracodes, Atol das Rocas, Ilha da Trindade, zoogeografia, paleozoogeografia.

Ostracoda (Crustacea) from the Archipelago of São Pedro and São Paulo, Equatorial Atlantic, with emphasis on a new Hemicytheridae genus

“…Coimbra & Carreño (2012), based on a small number of samples, recorded 21 ostracode species from Trindade Island (20°30'S, 29°18'W) and 23 species from Rocas Atoll (03°52'S, 33°09'W), while herein only 14 species were registered. Wouters (2003) described 13 species recovered from five intertidal samples collected from the island São Vicente (16°36'N, 24°34'W), Archipelago of Cabo Verde.…”

“…Therefore, it is also very likely that the tiny area of the ASPSP together with its great isolation, contribute to the low diversity of ostracode registered there. Finally, it is worth remembering that the Trindade Island and Rocas Atoll are not only much larger than ASPSP, but also components of two chains of seamounts associated with the Trindade-Vitória Alignment and the Fernando de Noronha Fracture Zone, respectively (Coimbra & Carreño, 2012). Thus, it was expected that these latter two oceanic islands have a greater diversity of Ostracoda than the ASPSP.…”

“…Larwood & Whatley, 1993), that areas isolated over millions of years have higher levels of endemism than those with continual or intermittent shallow submarine connections with the mainland or other islands. Although the other three Brazilian oceanic islands, i.e., Fernando de Noronha Archipelago, Trindade/Martim Vaz and the Rocas Atoll have submarine connections with the mainland (see Coimbra & Carreño, 2012), the ASPSP fits well in the first case since it is distant ~1,100 km from the coast of Brazil and its rocks rise from a depth of ~3,800 m (Motoki et al, 2009). This isolation is a major contributor to the high endemism among benthic invertebrates in this archipelago (see Amaral et al, 2009;Moraes et al, 2009;Oliveira et al, 2009).…”

New species of Xestoleberididae (Crustacea, Ostracoda) from Archipelago of São Pedro and São Paulo, Equatorial Atlantic

“…In Coimbra (2008), in a study of littoral benthic meiofauna of the State of São Paulo, recorded only five specimens of a species of this genus that remained in open nomenclature. Coimbra et al (2009) and Coimbra & Carreño (2012), in a preliminary study of ostracodes from the Trindade Island (20°30'S, 29°18'W) and Rocas Atoll (03°52'S, 33°09'W), two oceanic Brazilian islands, recorded Xestoleberis sp. in Trindade and Xestoleberis spp.…”

“…In recent decades, the study of the Brazilian oceanic islands and their flora and fauna has grown significantly with the financial support of the governmental program known as PROARQUIPÉLAGO. This program is also responsible by the logistical support to the researches performed in the Archipelago of São Pedro and São Paulo, that is a group of very small rocky islets in the Equatorial Atlantic Ocean (Campos et al, 2003;Coimbra et al, 2009Coimbra et al, , 2013antonietto et al, 2012;Coimbra & Carreño, 2012). Coimbra et al (2013) is an important contribution to the knowledge of the ostracod fauna from the Archipelago of São Pedro and São Paulo.…”