Oreaster reticulatus (Linnaeus, 1758)

Gondim, Anne Isabelley, Christoffersen, Martin Lindsey & Pereira Dias, Thelma Lucia, 2014, Taxonomic guide and historical review of starfishes in northeastern Brazil (Echinodermata, Asteroidea), ZooKeys 449, pp. 1-56 : 11-13

Oreaster reticulatus (Linnaeus, 1758) Figure 8a-g, 12c

Asterias gigas Linnaeus, 1753: 114.

Asterias reticulata Linnaeus, 1758: 661.

Pentaceros reticulatus Gray, 1840: 276.

Oreaster reticulatus Linnaeus, 1758. Tommasi 1958: 16-17, pl. 3, fig. 2; 1970: 10-11, fig. 31. Brito 1962: 3; 1968: 5-6, pl. 2, figs 1-3. Lima-Verde 1969: 11. Fernandes et al. 2002: 422. Magalhães et al. 2005: 63. Ventura et al. 2007: 238. Manso et al. 2008: 185, fig. 8c, d, e. Xavier 2010: 75. Alves et al. 2010: 757. Miranda et al. 2012: 143, 144.

Oreaster aculeatus Müller & Troschel, 1842: 50.

Oreaster lapidarius Grube, 1857: 342.

Oreaster tuberosus Möbius, 1859: 6.

Oreaster gigas Lütken, 1860: 64-75.

Oreaster reticulatus var. bermudensis H.L. Clark, 1942: 372, figs 1-2.

Material examined.

Ceará: off Fortaleza, 1spec., UFPB/ECH.1255, Geomar XXIV, V.1985. Paraíba: 1spec., UFPB/ECH.1579, 26.X.1980; Cabedelo, Farol de Cabedelo Reef, UFPB/ECH.1254, 22.I.1981, 26m; 1spec., UFPB/ECH.1588, 26.X.1980; 6°39'S; 34°49'W, 1spec., UFPB/ECH.1575, 28.V.1981, 20m; 6°39'5"S; 34°46'W, 1spec., UFPB/ECH.1429, 1spec., 29.V.1981, 35m; 6°39'05"S; 34°49"W, 1spec., UFPB/ECH.1251, 28.V.1981, 20m; 6°39'05"S; 34°49'W, 1spec., UFPB/ECH.1578, 28.V.1981, 20m; 6°50'S; 34°47'W, 1spec., UFPB/ECH.1253, 11.V.1981, 18m; 6°52'S; 34°46'W, 1spec., UFPB/ECH.1872, 19.II.1981, 18m; 6°52'S; 34°48'W, 1spec., UFPB/ECH.1590, 04.II.1981, 10m; 6°52'S; 34°49'W, 1spec., UFPB/ECH.1593, 04.II.1981, 12m; 6°57'S; 34°41'W, 1spc., UFPB/ECH.1577, 12.II.1981, 26m; 7°01'S; 34°47'05"W, 2spec., UFPB/ECH.1252, 02.V.1981, 11m; 7°04'S; 34°41'W, 2spec., UFPB/ECH.1576, 17.II.1981, 22m; 07°04'24,4"S; 034°47'49"W, 1spec., UFPB/ECH.1871, 24.VI.2005, 6m; 7°07'S; 34°47'W, 1spec., UFPB/ECH.1430, 05.II.1981, 10m; 7°10'S; 34°38'W, 1spec., UFPB/ECH.1873, 26.03.1981, 25m; 7°13'S; 34°42'W, 1spec., UFPB/ECH.1574, 27.III.1981, 10m; 7°34'S; 34°39'W, 1spec., UFPB/ECH.1594, 1spec., 7°34'S; 34°39'W, Paraíba, 22.I.1981, 26m. Pernambuco: Itamaracá Island, 4spec., UFPB/ECH.1581, VIII.1980, 20m; Suape Beach, 1spec., UFPB/ECH.1580, I.1980.

Type locality.

'Las Antillas Occidentales’ or 'Spanish West Indies’ ( Clark and Downey 1992).

Description.

Body pentagonal. Disk high, inflated, concave on actinal side (Fig. 8a, b). Five short arms (Fig. 8a). Abactinal figs with one thick, short, blunt spine (~2.43 mm). Among these figs there occur papular areas, which are covered by small granules and bivalve pedicellariae (Fig. 8c). These granules cover the entire body, including the bases of the spines. Superomarginal figs with one short, thick and blunt spine (~3.38 mm), determining the margin of the body. Inferomarginal figs similar to superomarginal figs, with one or two small and thick spines. Papular areas restricted to abactinal surface. Actinal surface granulose, with a great number of pedicellariae, especially in areas near the mouth and abulacral groove. Actinal figs with 1-2 short, conical, and blunt spines (~1.53 mm). Ambulacral figs with 5-6 short and flattened spines, of which the median spines are the largest (Fig. 8e). Short, conical, spines (~3.16 mm) form a well defined row of spines on the margins of the ambulacral grooves. Four short, thick, blunt oral spines (Fig. 8d). Sessile bivalve pedicellariae distributed over entire body of animal (Fig. 8f). Skeleton formed by conical, abactinal figs interconnected by secondarily elongated and widened figs, arranged into a reticulum (Fig. 8g).

Colour. According to Hendler et al. (1995) and Verrill (1915) the colour pattern of this species is very variable, even among individuals from a same population. Along the Brazilian coast the most common colour is orange or brownish red. Yet juvenile individuals differ significantly from adults. According to Benavides-Serrato et al. (2011) and Hendler et al. (1995) the aboral surface of juveniles is frequently olive-green and usually presents green-grey or coffe-coloured spots. In the adults, on the other hand, this colour is orange with lighter or darker tubercles on the disk and arms. The oral surface in both stages is beige or cream-coloured.

Distribution.

North and South Carolina, the Bermudas, the Bahamas, Belize, Guatemala, Honduras, Cuba, Nicaragua, Costa Rica, Venezuela, Brazil, and Cabo Verde ( Tommasi 1970, Walenkamp 1976, Hendler et al. 1995, Ventura et al. 2007, Alvarado et al. 2008, del Valle García et al. 2008). In Brazil: MA, CE, PB, PE, AL, BA, RJ, SP, and SC, incluinding Abrolhos and Trindade Island ( Rathbun 1879, Verrill 1915, Clark 1942, Tommasi 1958, 1970, Brito 1962, 1968, Lima-Verde 1969, Fernandes et al. 2002, Magalhães et al. 2005, Xavier 2010, Miranda et al. 2012). In this study we record the species for the first time in the States of Rio Grande do Norte, and Alagoas. From 0 to 800 m in depth, being most abundant up to 50 m.

Remarks.

Only two species of the genus Oreaster are known for the Atlantic Ocean, Oreaster clavatus and Oreaster reticulatus . The first is known only from the Island of Cape Verde, São Thomé and the Gulf of Guinea. The second, occurs widely throughout the West Atlantic, from North Carolina to the south of Brazil ( Clark and Downey 1992), its known southern limit being located in the State of Santa Catarina. Oreaster reticulatus differs from its congeneric Oreaster clavatus for presenting an inflated body and abactinal figs with tubercules or spines. Clark (1942) described the variety Oreaster reticulatus var. bermudensis on the basis of the irregular placement of spines and papulae on the abactinal surface and of the presence of only one spine on the actinal figs. However, these characters also occur in other specimens from the Atlantic and thus do not sustain the name. According to Hendler et al. (1995) the species may attain a disk diameter of up to 500 mm. We observed morphological variations in both juveniles and adults, but were not able to correlate these with colour patterns in this preserved material.

Ecological notes.

The species lives in shallow reef environments with calm water, coastal lagoons, seagrass beds ( Thalassia , Halodule and Syringodium ), and mangrove channels ( Benavides-Serrato et al. 2011). In this study the species was recorded in rhodolite beds and coastal reefs below 6 m. According to Verrill (1915) Oreaster reticulatus was the most abundant species in the States of Bahia and Pernambuco. Presently it is difficult to find along the northeastern coast of Brazil, and is listed as vulnerable to extinction ( Machado et al. 2008). This is an omnivorous species, feeding mainly on microorganisms from organic matter associated with the sand of seagrass beds and algal substrates. However, it is also an opportunistic predator of echinoderms, such as Tripneustes ventricosus (Lamarck, 1816) and Meoma ventricosa ventricosa (Lamark, 1816), as well as of individuals belonging to its own species and to a large variety of sponges ( Hendler et al. 1995). The only known predator of adults belonging to this species is the gastropod Charonia variegata (Lamarck, 1816), while young individuals are known to be eaten by a great variety of fishes ( Scheibling 1980).