Luidia alternata alternata ( Say, 1825 )

Cunha, Rosana, Martins, Luciana, Menegola, Carla & Souto, Camilla, 2021, Taxonomy of the sea stars (Echinodermata: Asteroidea) from Bahia State, including ontogenetic variation and an illustrated key to the Brazilian species, Zootaxa 4955 (1), pp. 1-78 : 19-21

Luidia alternata alternata ( Say, 1825)

Figure 8

Asterias alternata Say, 1825: 144–145 .

Luidia alternata — Brito 1968: 12–13, pl. 3, fig. 4; Tommasi & Aron 1987: 5; Tommasi et al. 1988: 6; Ventura et al. 2007: 236; Miranda et al. 2012: 9; Miranda 2018: 14, fig. 10B; Torres & Torres 2019: 413.

Luidia alternata alternata — Clark & Downey 1992: 8–9, figs. 4b, c, 5d, 6f, 7a–g, q, 8a, b, pl. 1B; Pérez-Ruzafa et al. 1999: 45, fig. 1A; Entrambasaguas 2003: 68–71, fig. 1; Magalhães et al. 2005: 63; Entrambasaguas 2008: 41–43; Gondim et al. 2014: 7 , 9, figs. 3a–d; Alitto et al. 2016: 10, figs. 7c–d; Borrero-Peìrez et al. 2019: 4; Cunha et al. 2020: 47 , fig. 4F.

Material examined (1 spec, 45 mm R). BRAZIL. Bahia, Porto Seguro (16°20’S; 38°14’W)— 40 m, 30.vi.2001, 1 spec ( EQMN 2007 ) .

Comparative material. U.S.A. Florida , Dry Tortugas, 1 spec, R 170 mm ( NHM-UK 1937.5 .9.6, neotype) .

Description (R 45 mm). Flat disc ( Fig. 8A ). Five robust arms. Abactinal plates covered by paxillae of varied sizes ( Fig. 8C ). Larger paxillae with a prominent central spine (~ 1.5 mm) and two rows of peripheral spinelets with denticulate tips: first row with few short spinelets; second row with many long, denticulate spinelets. Smaller paxillae with small and robust central spinelets, and one row of long and denticulate peripheral spinelets. Madreporite inconspicuous, hidden by paxillae. Superomarginal plates paxilliform, inconspicuous. Inferomarginal plates elongated and separated by a gap. Marginal region of plates with two long spines arranged horizontally; actinal surface of inferomarginal plates densely covered by flat spines of varying shapes and sizes and three long located centrally. Three large, curved adambulacral spines arranged in a row along center of plate, perpendicular to furrow. One curved, marginal subambulacral spine larger than surrounding spines, but smaller than spines on center of plate ( Fig. 8F ). Oral plate prominent, with slender and unequal spines ( Fig. 8D ). Tube feet in two rows, sucking disc lacking ( Fig. 8B ). Pedicellariae short, with four hyaline valves, inconspicuous and placed adjacent to ambulacral furrow (likely in development).

Coloration. No record of coloration of in vivo specimens from this region but live specimens from Trindade Island ( Cunha et al. 2020) display the same coloration pattern as the fixed specimen described here: abactinal region with dark scarlet red to brown transverse bands, actinal region yellow beige, spines white. H.L. Clark (1933) noticed that the coloration of this species is not affected by alcohol or other preservation fluids.

Distribution. U.S.A. (NC, FL), Gulf of Mexico, Mexico, The The Bahamas, Caribbean Sea, Cuba, Dominican Republic, Honduras, Panama, Colombia, Venezuela, Guyana, Uruguay, Argentina, Cape Verde ( Clark & Downey 1992; Pérez-Ruzafa et al. 1999; Entrambasaguas 2003, 2008; Borrero-Peìrez et al. 2019; Mah 2020a). BRAZIL: Amapá, Pará, Paraíba, Alagoas, Bahia, Espírito Santo, Trindade Island, Rio de Janeiro, São Paulo, Santa Catarina, Rio Grande do Sul ( Verrill 1915; Brito 1962, 1968; Tommasi 1970; Carrera-Rodríguez & Tommasi 1977; Walenkamp 1979; Tommasi & Aron 1987; Magalhães et al. 2005; Ventura et al. 2007; Miranda et al. 2012; Gondim et al. 2014; Alitto et al. 2016; Miranda 2018; Torres & Torres 2019; Cunha et al. 2020). Depth. 1–200 m ( Clark & Downey 1992).

Biological notes. Luidia alternata alternata inhabits sandy and muddy bottoms, and it is also found in coral reefs and mangroves, often associated with shells and calcareous algae ( Clark & Downey 1992; Hendler et al. 1995; Cunha et al. 2020; present paper). Although this subspecies occurs in shallow water, it is rarely encountered in shallow habitats from Bahia when compared to L. clathrata and L. senegalensis . Its diet is carnivorous, mostly limited to epifaunal organisms including other sea stars such as A. articulatus and L. clathrata ( Schwartz & Porter 1977; Ventura et al. 2007).

Luidia alternata alternata is classified as “Least Concern” by the Ministry of the Environment ( MMA 2018). According to Gurjão & Lotufo (2018), its harvesting in Brazil is currently prohibited.

Neotype. NHM-UK 1937.5 .9.6.

Type locality. Dry Tortugas, FL, U.S.A.

Remarks. The only specimen examined has a total length of 60 mm, with an r of 7 mm. Because all arms are regenerating or damaged, we did not include the R/r ratio.

Gondim et al. (2014) found pedicellariae with 2–4 valves in the specimens from Paraíba (north of Bahia). The pedicellariae from the specimen described here are short and seem to be in a formation state, but they all have four valves; and the pedicellariae from the neotype are long, formed by 3–4 valves and placed around the mouth and adjacent to the ambulacral furrow. With regards to the number of inferomarginal spines, the neotype (R 170 mm) has 2–3 spines, the specimen described here has two spines, and Gondim et al. ’s (2014) specimens (R 3–20 mm) have 1–2 spines. This variation is most likely ontogenetic, with the number of inferomarginal spines increasing over time up to three. According to H.L. Clark (1933), adult specimens of L. alternata alternata have R 120–130 mm, and the largest specimen known until that date had R 175 mm.

Luidia alternata alternata differs from Luidia alternata numidica Koehler, 1911 by having only single central spinelets on many of the smaller paxillae (vs. more numerous central spinelets on many of the smaller paxillae).

Figures

FIGURE 8. Specimen (R 45 mm) of Luidia alternata alternata (Say, 1825) (EQMN 2007): (A) abactinal and (B) actinal view of body; (C) paxillae in the abactinal plates; (D) oral region; (E) abactinal paxillae and marginal spines; (F) ambulacral furrow (proximal region on the right). Scale bars: A–B, 20 mm; C, F, 2 mm; D, 4 mm; E, 5 mm.