Intracolonial variation in Siderastrea de Blainville, 1830 (Anthozoa, Scleractinia): taxonomy under challenging morphological constraints

Abstract

The morphology of sessile invertebrates, such as scleractinian corals, can be controlled by environmental and genetic mechanisms and, consequently, it is highly variable. Morphological variation has puzzled taxonomists by posing challenges to species classification within cryptic species complexes. The 'Atlantic Siderastrea Complex' is a suitable example. Because of overlapping diagnostic traits, the morphological interspecific limits of this group remain controversial and often resulted in doubtful synonyms. In addition, the recent identification of the Caribbean S. radians in the Southwestern Atlantic has revealed that intraspecific variation has been equivocally assessed. Traditionally, hierarchical categories of variation have been the criteria used to investigate the patterns of modular organisms as corals. However, despite its taxonomic and ecological implications, the category 'intracolonial' has been largely neglected. To evaluate the influences of intracolonial morphological variation in the identification of Atlantic siderastreids, colonies from Bahia State, northeastern Brazil, were collected and measured. Six characters were selected in S. radians and S. stellata, and the variation in these characters was analyzed with Discriminant Canonical Analysis. The columellar depth and diameter varied consistently within S. stellata and S. radians, but the septal number was the most important for differentiating the two species. The results of the study also represent the first report of S. radians on the northern coast of Bahia.

Morphological variation in the atlantic genus Siderastrea (Anthozoa, Scleractinia)

“…Best et al (1983) propose a new dimension to the analysis in Scleractinia taxonomy when suggest that in fossil record and current species, within a geographically limited area, the intraspecific variation can be 'intracolonial', 'intrapopulation' and 'interpopulation'. Menezes et al (2013) observe that intracolonial variation is not an important problem to differentiate S. stellata from S. radians. In the present study, we focus on the others categories of morphological variation, describing the intraspecific and interspecific variation of S. stellata and S. radians in Brazilian reef systems.…”

“…Most studies on morphological variation of the 'Atlantic Siderastrea Complex' were realized with S. siderea (Foster, 1979(Foster, , 1980. In Brazil, a few studies focus in describe morphological variation of siderastreids (Werner, 1996;Neves, 2004;Santos et al, 2004;Neves et al, 2010;Menezes et al, 2013).…”

“…The complete fourth cycle of septa for S. stellata has been cited by diverse authors such as Verrill (1868Verrill ( , 1901, Gravier (1909), Vaughan (1919), Yonge (1935), and posteriorly by (Neves, 2004;Neves et al, 2010 andMenezes et al, 2013). However, it is important to highlight a common confused interpretation.…”

“…Siderastrea stellata Verril, 1868 is endemic to Brazilian coast (from Parcel do Manuel Luis to northern coast of Rio de Janeiro) (Leão, 1986;Amaral et al, 2007). Siderastrea radians (Pallas, 1766) and Siderastrea siderea (Ellis & Sollander, 1789) are some of the most common corals in the Caribbean region (Neves, 2004) and, recently, they were also registered in Brazilian coast (Neves et al, 2006(Neves et al, , 2008(Neves et al, , 2010Menezes et al, 2013).…”

Serviços ecossistêmicos prestados por recifes de coral nas ilhas de Tinharé e Boipeba, Baixo Sul da Bahia, Brasil

“…A classificação "alto" se refere às áreas do mapa com um risco acumulado de >66% da pontuação máxima de risco para qualquer combinação de fator de estresse/habitat, "médio" entre 33-66%, e "baixo" risco entre 0-33%. Diante do recente estudo de Menezes et al (2013), no qual é discutida a problemática da identificação de espécies crípticas do complexo Siderastrea do Atlântico, optou-se por utilizar a abreviatura "spp." para todas as colônias identificadas dentro desse gênero para evitar identificações equivocadas.…”