Asterinides folium ( Lütken, 1860 )

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 : 33-36

Asterinides folium ( Lütken, 1860)

Figures 17–18

Asteriscus folium Lütken, 1860: 60 .

Asterina folium — Clark & Downey 1992: 182, pl. 421, figs. 31–32; Hendler et al. 1995: 74, fig. 18.

Asterinides folium — O’Loughlin 2002: 293, fig. 7; O’Loughlin & Waters 2004: 17, fig. 8; Oliveira et al. 2010: 3, fig. 2a; Bena- vides-Serrato et al. 2011: 150; Gondim et al. 2014: 24, fig. 7a–e; Sandino et al. 2017: S294; Souto & Martins 2017: 304; Cunha et al. 2020: 46.

Material examined (8 specs, 2–7 mm R). BRAZIL. Bahia (12°47’– 13°05’S; 38°08’– 38°39’W)— Busca Vida beach, Guarajuba, 23 m, 1.ii.2006, 1 spec, R 2 mm ( UFBA 685 ); 23 m, i.2010, 4 specs, R 2–2.6 mm ( UFBA 983 , 1076 ); 25 m, vii.2010, 1 spec, R 1.5 mm ( UFBA 1163 ). Todos os Santos Bay , 12 m, 5.iv.1997, 1 spec, R 2 mm ( UFBA 1107 ). Salvador, Itapuã beach, 1 m, 19.ii.2007, 1 spec, R 7 mm ( UFBA 528 ) .

Comparative material. Asterinides pilosa: BRITISH VIRGIN ISLAND. Caribbean Sea, 9–12 m, 11.v.1976, 2 specs, R 3–3.8 mm ( CASIZ 112487 ). Asterinides pompom : The Bahamas. Whitehorse Cay, 9 m, 28.vi.1998, 1 spec, R 13 mm ( CASIZ 117432 ) .

Description of largest specimen (R 7 mm). Body stellate ( Fig. 17A–D ), disc inflated; R/r 1.4. Five arms. Abactinal plates regularly arranged, imbricated ( Fig. 17C ), with tufts of spinelets (up to 12 in proximal plates) in proximal edge, and thick crystalline bodies. Terminal plates naked. Madreporite large, suboval, sunk between proximal plates ( Fig. 18B ). Primary plates heart-shaped ( Fig. 18A ). Papular areas small, conspicuous, with one papula ( Fig. 18B ), forming a longitudinal series of six areas along each arm. Superomarginal plates with 15–20 slender spines. Inferomarginal plates with tufts of 17–20 spinelets projected outwards ( Fig. 18E ). Actinal plates with 2–3 pointed spines, central spine often longest ( Fig. 18F ). Three adambulacral spines, webbed, central spine often longest ( Fig. 18D ). Two to three subambulacral spines, webbed ( Fig. 18D ). Oral plates with six oral spines and four suboral spines, all webbed ( Fig. 18C ). Tube feet in two rows, sucking disc present. Pedicellariae absent.

Ontogenetic variation (R 1.5–2.6 mm). Average R/r 1.4. Differs from the largest specimen by having a pentagonal shape; juxtaposed abactinal plates; primary plates rosette-shaped ( Fig. 17E ); a pair of papular area per interradius, in proximal region; few or no actinal spines; tufts of inferomarginal spines conspicuous; two oral spines. Also, the smallest specimen (R 1.5 mm) has only one spine per adambulacral plate.

Coloration. Specimen in vivo has scarlet red abactinal region and white to yellowish actinal region, with orange edge. Specimens in ethanol are white to beige.

Distribution. Bermuda, U.S.A. (FL), Gulf of Mexico, Mexico, The The Bahamas, Puerto Rico, Belize, Jamaica, Nicaragua, Panama, Colombia, Venezuela ( Verrill 1915; Clark & Downey 1992; Hendler et al. 1995; Alvarado et al. 2008; Benavides-Serrato et al. 2011; Sandino et al. 2017). BRAZIL: Paraíba, Bahia, Trindade Island, Rio de Janeiro ( Brito 1968, 1971; Tommasi 1970; Clark & Downey 1992; Alvarado & Solís-Marín 2013; Gondim et al. 2014; Souto & Martins 2017; Cunha et al. 2020). Depth. 0–25 m ( Clark & Downey 1992; present paper).

Biological notes. Specimens from Bahia live under rocks, in sandy and calcareous bottoms, often in isolation. Specimens from Trindade Island also live under rocks but in densities of 25 specimens per site ( Brito 1968; 1971). Specimens from the Caribbean are also solitary and their coloration varies with size: juvenile specimens are white, intermediate specimens are red, yellow or yellowish, and adult specimens are blue and blue-green ( Hendler et al. 1995). Souto & Martins (2017) reported that the sites from Camaçari, Bahia, are recruitment areas for A. folium populations since only small specimens were found at those sites; their coloration was not recorded by collectors. The larger specimen was collected in the shallow subtidal region.

Syntype. NHMD 76237 [previously as ZMUC AST 69 ] (Tom Schiøtte, per. comm) .

Type locality. St. Thomas, U.S. Virgin Islands ( Lütken, 1860).

Remarks. Clark & Downey (1992), O’Loughlin (2002) and O’Loughlin & Waters (2004) reported additional intraspecific variation not observed here, including the presence of 4–6 arms (vs. 5 arms); up to 20 spinelets in the proximal plates (vs. up to 12); 2–5 spines on the actinal plates (vs. 2–3); 3–5 adambulacral spines (vs. three). The specimens described in these papers were up to R 19 mm (vs. up to R 7 mm in the present study) and although they do not mention ontogenetic variation, the higher number of spines and spinelets reported may be related to size. H.L. Clark (1933) noted that adult specimens have at least R 10 mm.

Asterinides folium differs from A. pilosa by having five arms, rays not clearly defined, and up to five spines in actinal plates (vs. six arms, distinct rays and clusters of small spines), from A. hartmeyeri by having a fringe of 15–20 inferomarginal spinelets (vs. 6–10 spinelets), and from A. pompom by having a stellate shape and single papulae (vs. pentagonal shape with indistinct rays and paired papulae in the middle of the arm). Also, A. pompom has an inflated petaloid area in the abactinal region and a granulose structure with a cluster of thin spinelets in most abactinal plates. For a thorough revision of the genus Asterinides , see O’Loughlin & Waters (2004).

Figures

FIGURE 17. Specimen (R 7 mm) of Asterinides folium (Lütken, 1860) (UFBA 528): (A) abactinal and (B) actinal view of specimen in vivo, (C) abactinal view showing imbricate proximal plates and (D) actinal view. Specimen (R 2 mm) (UFBA 1107): (E) abactinal view showing proximal petaloid structure and (F) actinal view showing ambulacral furrow and oral region. Scale bars: A–D, 5 mm; E–F, 1 mm.

FIGURE 18. Specimen (R 7 mm) of Asterinides folium (Lütken, 1860) (UFBA 528): (A) detail of disc showing heart-shaped primary plates; (B) madreporite without twists; (C) oral region; (D) ambulacral furrow; (E) abactinal view of the marginal plates with spines; and (F) spines on the interradial actinal plates. Scale bars: A–B, D–F, 1 mm; C, 2 mm.