Luidia senegalensis (Lamarck, 1816)

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 : 5-6

Luidia senegalensis (Lamarck, 1816) Figures 4e-h, 12a

Asterias senegalensis Lamarck, 1816: 567.

Luidia senegalensis Müller & Troschel, 1842: 78. Tommasi 1958: 9, pl. 2, fig. 1; 1970: 8, fig. 21; 1985: 3. Brito 1968: 10-11, pl. 3, fig. 1. Lima-Verde 1969: 10. Nomura and Fausto Filho 1966: 19. Fernandes et al. 2002: 422. Magalhães et al. 2005: 63. Manso et al. 2008: 185, fig 8c-e. Lima and Fernandes 2009: 58. Xavier 2010: 75.

Luidia marcgravii Steenstrup in Lütken 1859: 43-46.

Material examined.

Rio Grande do Norte: Timbau Beach, 3 spec., UFPB/ECH.1582, 28.II.1980; Areia Branca, Ponta do Mel, 1spec., UFPB/ECH.1428, 23.VI.1982. Paraíba: Lucena, Costinha Beach, 5 spec., UFPB/ECH.1673, 08.XI.2003; Cabedelo, Miramar Beach, 4spec., UFPB/ECH.1256, 03.II.1983; Cabedelo, Santa Catarina Beach, 1spec., UFPB/ECH.1583, 18.V.2007; Paraíba do Norte River Estuary, 1spec., UFPB/ECH.89, 18.06.1980; 1spec., UFPB/ECH.1586. 13.VI.1983.

Type locality.

Supposedly Senegal ( ‘L’ océan d’Afrique, les côtes du Senegal’), but probably West Indies ( Clark and Downey 1992).

Description.

Body flattened. Disk rounded. Nine long and narrow arms (rarely 7) (Fig. 4e, f). Paxillae on abactinal surface. Paxillae small, arranged irregularly, occupying center of disk and of arms. Paxillae of carinal regions rounded, with 1-4 central, short, rounded spinelets and 12-16 marginal spinelets disposed into two rows. Adradial paxillae quadrangular, disposed in regular longitudinal and tranversal rows, bearing 4-10 central, short, rounded spines (Fig. 4g). Inferomarginal figs with two short, conical and slightly compressed spines (~2.20 mm), the upper one being the smallest. Towards the mouth the inferomarginal figs are covered by short, lanceolate spines (Fig. 4f). Between these and the lateral margins slender spinelets occur. Adambulacral figs with four spines, two elongate, compressed and slightly curved adambulacral spines, and two elongate, flattened and lanceolate subambulacral spines (Fig. 4h). Oral spines long (~2.59 mm) and thin, forming a dense tuft of spines on the apex of jaw. Ocular figs well developed and grunuliform. Pedicellariae absent.

Colour. Dorsally bluish-grey or greenish-gray, with a strong dark line along the central region of the disk and of the arms. The actinal surface is white to cream-coloured.

Distribution.

Florida, Cuba, Jamaica, Honduras, Nicaragua, Costa Rica, Panama, Venezuela and Brazil ( Tommasi 1958, Clark 1982, Abreu-Pérez et al. 2005, Alvarado et al. 2008, del Valle García et al. 2008). In Brazil: PI, CE, PB, PE, AL, BA, RJ, SP, and SC ( Rathbun 1879, Verrill 1915, Bernasconi 1943, Krau 1950, Tommasi 1958, 1970, Brito 1962, 1968, Lima-Verde 1969, Fernandes et al. 2002, Magalhães et al. 2005, Gondim et al. 2008, 2013, Gondim and Giacometti 2010, Xavier 2010, Miranda et al. 2012). This study provides the first record for the coast of Rio Grande do Norte. From 1 to 64 m in depth, being rare below 40 m ( Clark and Downey 1992).

Remarks.

Distinguished from the remaining species from Brazil by the presence of 7 to 9 arms. Luidia barbadensis Perrier, 1881, recorded for Bahamas, Florida, Gulf of Mexico and south Brazil is the closest species, but it may be distinguished from Luidia senegalensis for having 6 arms, inframarginal figs with two long and narrow spines, and the usual presence of pedicellariae. Walenkamp (1979) identified one specimen with 6 arms from Guyana as Luidia senegalensis . His identification was questioned for some time, but the presence of dark bands on the carinal region of the arms and disk and the depth of collection (32 m, while the minimum known depth of Luidia barbadensis is 73 m) confirm the validity of this identification ( Clark and Downey 1992). Our observation of both juvenile (dd ≤ 15 cm) and adult individuals permitted the conclusion that morphological characters do not vary during ontogeny. Thus forms with less than 7 arms or more than 9 arms (this later condition never having been observed in nature) must be the result of failures during metamorphosis ( Hotchkiss 2000). As for the remaining Paxillosida , the structure of the paxillae represent a key taxonomic character for the identification of species.

Ecological notes.

The species lives in environments of low hydrodynamism, in sediment containing sand, mud, or a combination of both of these ( Hendler et al. 1995). It feeds mainly on molluscs, but also of other echinoderms such as sea-stars of the genus Astropecten and irregular echinoids, as well as ophiuroids, copepods, decapods, scaphopods, and polychaetes ( Penchaszadeh and Lera 1983). Sometimes a small commensal crustacean ( Minyoceras angustus Dana, 1852) is found in the interior of its ambulacrum. This crustacean was also observed in Luidia clathrata ( Brito 1960). According to Hendler et al. (1995), individulas may attain 30-40 cm in disk diameter (dd), and attain sexual maturity when at 15 cm in diameter. Presently it is considered vulnerable to extinction along the Brazilian littoral. The main causes of population decline are its high succeptibility to the effects of pollution of the water column and the frequent accidental capture in trawling nets ( Machado et al. 2008).