Comparação morfométrica do esqueleto Agaricia agaricites (Linnaeus, 1758) e Siderastrea stellata Verrill, 1868 (Cnidaria: Seleractina) no Litoral Paraibano e Norte - Rio - Grandense.

Abstract

The study of morphological variation of the scleractinian coral exoskeleton is important for the taxonomy and also to elucidate how the adaptive process of this animal to the environment occurs. The aim of this study was to describe, qualitatively and quantitatively, the morphology of the coral skeleton of Agaricia agaricites and Síderastrea stellata of reef environments of Picãozinho and Carapibús in the state of Paraíba/Brazil and Pirangi, in the state of Rio Grande do Norte/Brazil, comparing the specimens of each locality. Samples were collected in July/ 2010, by apnea diving with the aid of a hammer and chiesel, and it was collected tive fragments of S. stellata coral in each studied area and tive fragments of A agaricites in the Reefs of Picãozinho, totaling twenty colonies analyzed. In the Laboratório de Pesquisa de Invertebrados Marinhos (LAPEIMAR I UFCG), the specimens were placed in a solution of sodium hypochlorite (30%) to remove the soft tissue, and dried naturally. Twenty corallite per colony were analyzed and among the studied aspects with the aid of a stereoscopic microscope, relevant literatura, we present: the colony and corallites form; height and diameter of the colony; corallites diameter; number of septa per corallites; columellar distance and number of columella centers per cm2 ; epibiont number and substrate type. Quantitativa data were through the STATISTICA ® program, v. 4.0. The main results of the analysis were the occurrence of a uniform morphology of S. stellata colonies. As for A agaricites, the shape of the colony was predominantly flat. The mean diameter of corallites of S. stellata was 4.51 mm (± 0.92) for colonies in Picãozinho and 4.22 mm (± 0.67) for specimens in Carapibús. Comparing the diameter of S. stellata corallites by Student's t test, there was a significant difference (t= 2,56; gl= 198; p<0,05) between the population analyzed. A agaricites exhibited a mean diameter of the coralfites of 2.17 mm (± 0.48). The number of columella average per cm2 was similar to S. stellata in both environments (Picãozinho = 16.27; Carapibus = 17.27). Dueto the morphological peculiarities of A agaricites, this feature presented an average value numerically higher (45.80 colu/cm2 ) . The latter species also showed the existence of coral conspicuous epibiont organisms in the exoskeleton in relation to S. stellata in the same place, registering an average of 49.20 epibiont (± 56.37) for the former and 5.4 (± 2.07) for the latter. Through these results we consider differences between specimens S. stellata, from both localities and morphological peculiarities of the species A agaricites, showing the need to investigate a greater number of morphological structures of these species of scleractinian coral.