Luidia senegalensis (Lamark, 1816)

Figures 11–12

Asterias senegalensis Lamarck, 1816: 567 .

Luidia senegalensis — Tommasi 1958: 9, fig. 1, pl. 2; 1985: 3; Brito 1968: 10–11, fig. 1, pl. 3; Lima-Verde 1969: 10; Nomura & Fausto Filho 1966: 19; Nunes 1975: 183, figs. 3–4; Clark & Downey 1992: 21–22, pl. 4A; Hendler et al. 1995: 69–71, fig. 15; Fernandes et al. 2002: 422; Magalhães et al. 2005: 63; Manso et al. 2008: 185, fig. 8c–e; Lima & Fernandes 2009: 58; Magris & Deìstro 2010: 59, 61; Xavier 2010: 75; Benavides-Serrato et al. 2011: 107–108; Gondim et al. 2014: 14–15, figs. 4e–h, 12a; Nisperuza et al. 2016: 115; Alvarado et al. 2017: S276; Alitto et al. 2016: 10, figs. 7e–f; Sandino et al. 2017: S294; Bueno et al. 2018: 180, fig. 10; Gurjão & Lotufo 2018: 11; Miranda 2018: 14, fig. 10A; Rubio-Polania et al. 2018: 190; Borrero-Peìrez et al. 2019: 4; Torres & Torres 2019: 413; Turra et al. 2019; Magris & Giarrizzo 2020: 3.

Material examined (2 specs, 19–146 mm R). BRAZIL. Bahia, Todos os Santos Bay (12°46’– 12°51’S; 38°33’– 38°39’W)— 48 m, 29.iv.1997, 1 spec, R 19 mm (UFBA 592); 3 m, 22.v.1997, 1 spec, R 146 mm (UFBA 496) .

Description (R 146 mm). Nine long, flattened and slender arms (Fig. 11A–C); R/r 6.1. Abactinal surface covered by paxillae. Disc and central region of arm with small paxillae (Fig. 11D). Paxillae covered by 10–15 small, central granules and a fringe of fine peripheral spinelets. Paxillae in disc interradius are larger than others. Arm margins with two rows of rectangular paxillae (Fig. 11F). Madreporite irregularly shaped, often hidden by paxillae (Fig. 11E). Superomarginal plates paxilliform. Inferomarginal plates elongated and separated by a gap. Marginal region of plates with 1–2 short and pointed spines; below these, a fringe of fine, minute spines. Actinal surface of inferomarginal plates densely covered by flat spines, large in central region and minute in marginal region (Fig. 11G). Four adambulacral spines. Two curved spines, innermost spine smallest; two flattened spines of same size, side by side (Fig. 11H). Oral plate narrow, armed with a tuft of strong, long, slender spines (Fig. 11I). Tube feet in two rows, sucking disc lacking. Pedicellariae absent.

Ontogenetic variation (R 19 mm). R/r 3.8 (Fig. 12A–B); 1–3 central granules in paxillae (Fig. 12C). Central paxillae spaced out and not tightly packed as in large specimen (Fig. 12E). Inferomarginal plate with only one spine (Fig. 12G). Three adambulacral spines, the innermost curved.

Coloration. Specimen in vivo has greyish abactinal region, yellow beige marginal and actinal regions; specimens in ethanol are faded but generally maintain the same pattern.

Distribution. U.S.A. (FL), Gulf of Mexico, Mexico, The The Bahamas, the Caribbean, Cuba, Dominican Republic, Jamaica, Haiti, Puerto Rico, Honduras, Nicaragua, Costa Rica, Panama, Colombia, Venezuela, Guyana (Nisperuza et al. 2016; Alvarado et al. 2017; Sandino et al. 2017; Rubio-Polania et al. 2018; Borrero-Peìrez et al. 2019; Mah 2020a). BRAZIL: Amapá, Pará, Rio Grande do Norte, Paraíba, Pernambuco, Bahia, Rio de Janeiro, São Paulo, Paraná, Santa Catarina (Rathbun 1879; Brito 1960, 1968; Walenkamp 1976; 1979; Clark & Downey 1992; Manso et al. 2008; Gondim et al. 2008; 2014; Magris & Deìstro 2010; Alvarado & Solís-Marín 2013; Alitto et al. 2016; Bueno et al. 2018; Miranda 2018; Torres & Torres 2019; Turra et al. 2019). Depth. 1–64 m (Clark & Downey 1992).

Biological notes. Specimens from Bahia live in calm waters, on sandy or muddy bottoms (Manso et al. 2008; present paper), sometimes in regions of low salinity (21 ppt), such as the delta of the Paraguaçu River. Astropecten and Luidia species often live in sympatry, partitioning food resources (Ventura 1991; Queiroz 2006; Fernandez et al. 2017); however, populations from Ilhéus, Bahia, live in allopatry, with L. senegalensis mainly at around 15 m of depth and A. marginatus mainly at around 35 m (Pelaes 2008). None of the specimens of Astropecten and Luidia reported in this paper were collected in the same locality. Separation of resources may also occur within populations of L. senegalensis . Turra et al. (2019) noticed that adult individuals seem to migrate to deeper regions, possibly to use different resources. Interestingly, the specimens reported here have a different pattern, in which the smaller specimen was found in a deeper region than that of the large specimen.

Luidia senegalensis is not an abundant species. It has a yearly reproductive cycle in Southeastern Brazil, with spawning happening mainly during the rainy season (Turra et al. 2019). This species predates mainly on bivalves, but also feed on other invertebrates such as polychaetes and crustaceans (Monteiro & Pardo 1994), and it is preyed upon by other species of sea stars and sea shorebirds (Brites et al. 2008). With regards to behavior, Tagliafico et al. (2017) observed specimens from Cubagua Island, Venezuela, moving with only four arms in contact with the substrate, while the other five arms were held upright. Luidia senegalensis is used for medicinal purposes in Brazil to treat asthma, cough and metrorrhagia (Costa-Neto & Marques 2000; Alves & Rosa 2007; Alves & Alves 2011). Tangerina et al. (2018) presented a preliminary description of the chemical composition of specimens from São Paulo, but nothing related to pharmaceutical uses so far.

Luidia senegalensis is affected by shrimp fisheries, which collects this species as bycatch (Tangerina et al. 2018). In addition to this threat, Magris & Giarrizzo (2020) estimated that L. senegalensis is one of the most vulnerable species impacted by the oil spill recorded in the Brazilian coast in 2019. This species is classified as “Vulnerable” (baseline data indicates that the population size has been reduced by at least 30%) by the Ministry of the Environment (MMA 2018), and its harvesting in Brazil is currently prohibited (Gurjão & Lotufo 2018).

Syntypes. MNHN 2014-651, 2014-655, Muséum National d’Histoire Naturelle, Paris .

Type locality. Probably West Indies (Clark & Downey 1992).

Remarks. Walenkamp (1979) identified a specimen of L. senegalensis from Guyana with only six arms; Clark & Downey (1992) suggested this specimen could belong to L. barbadensis, but because of the presence of a dark stripe along the central region of the arm (vs. stripes in arms) and the depth that the specimen was collected (32 m vs. above 73 m in L. barbadensis), they confirmed Walenkamp’s identification. This specimen should certainly be re-examined since it is the only record of a L. senegalensis with six arms.