Astropecten aff. antillensis Lütken, 1859

Cunha, Rosana, Tavares, Marcos & Jr, Joel Braga De Mendonça, 2020, Asteroidea (Echinodermata) from shallow-waters of the remote oceanic archipelago Trindade and Martin Vaz, southeastern Atlantic, with taxonomic and zoogeographical notes, Zootaxa 4742 (1), pp. 31-56 : 47-49

Astropecten aff. antillensis Lütken, 1859

Figure 9

Astropecten antillensis Lu ̈tken, 1859: 47 [type locality: St. Thomas, Virgin Islands, viz. Clark & Downey, 1992]; Benavides- Serrato et al. 2011: 114; Alvarado & Solis-Marin, 2013: 605.

Trindade specimens. Brazil, Espírito Santo, Trindade Island, Ponta da Calheta , 20°30’20.29”S, 29°18’32.86”W , 10.viii.2018, 30 m: 1 spm R=40, r=5 ( MZUSP 2090 ) .

Comparative material. Astropecten brasiliensis Müller & Troschel, 1842 : Brazil, Rio de Janeiro, Ilha Grande, Ponta do Aripeba, 23º 07’05”S, 44º16’53”W, 21.i.2000, 1 spm R=65, r=11 ( MZUSP 2095). São Paulo, Ubatuba , 23°31’S, 45°02’W, 25.ix.2002, 9 m: 1 spm R=110, r=15 ( MZUSP 2099 ) . Caraguatatuba , 23°45’S, 45°13’W, 16.x.2001, 1 spm R=60, r=15 ( MZUSP 116 ) ; 19 m: 1 spm R=65, r=15 ( MZUSP 2098 ) . São Sebastião Island , 23°53’S, 45°26’W, 13.ii.2001: 4 spms R=55, r=8; R=53, r=8; R=32, r=6; R=19, r=4 ( MZUSP 118 ) ; xii.1915: 3 topotypes R=125, r=20; R=105, r=20; R=65, r=13 ( MZUSP 2096 ) ; 14.xii.2001, 20.3 m: 1 spm R=55, r=10 ( MZUSP 2097 ) . Astropecten marginatus Gray, 1840 : Brazil, São Paulo, Ubatuba , 23º31’S, 45º09’W, 16.iv.2002, 14 m: 2 spms R=36, r=24; R=18, r=12 ( MZUSP 00002 ) .

Distribution. Astropecten antillensis s. str., has been reported from Gulf of Mexico, Greater and Lesser Antilles, Colombia ( Sladen, 1889; Bayer et al., 1970; Clark & Downey, 1992; Abreu-Pérez et al., 2005; Alvarado & Solis-Marin, 2013). Brazil: Bahia ( John, 1948). Depth range: 3–278 m ( Clark & Downey, 1992).

Recognition characters. Two prominent spines in first pair of superomarginal plates, spines decreasing in size distally in remaining plates. Inferomarginal plates projecting beyond superomarginal ones. Inferomarginal spines broad, opaque. Two rows of subambulacral spines. First subambulacral row with three spines; middle spine wider and longer than proximal and distal ones, longer than furrow spines. Conspicuous bare area at center of actinal surface of inferomarginal plate. No pedicellariae ( Clark & Downey, 1992; Benevides-Serrato et al., 2011; Cobb et al., 2019; present study).

Color in life. Pale yellow (Lütken, 1859). The specimen in the photograph given by Benevides-Serrato et al. (2011) had orange body, with darker midline along each arm, and bright-red bands at the base of the inferomarginal fringe spines and superomarginal spines. The Trindade specimen was not photographed alive prior to preservation.

Habitats. The Trindade specimen was found on a whitish sandy bottom, around 30 meters depth.

Comments. The species in Astropecten can be separated into two groups according to the presence or absence of superomarginal spines. Among the eight species so far recorded from the Brazilian coasts, only A. cingulatus Sladen, 1833 and A. marginatus Gray, 1840 , are devoid of superomarginal spines. The six species with superomarginal spines are as follow: A. acutiradiatus Tortonese, 1956 , A. alligator Perrier, 1881 , A. antillensis Lütken, 1859 , A. articulatus ( Say, 1825) , A. brasiliensis Müller & Troschel, 1842 , and A. duplicatus Gray, 1840 .

Astropecten brasiliensis and A. cingulatus have both been previously recorded from Trindade ( Brito, 1962; Ventura et al. 2006; 2007). However, the Trindade specimen can be immediately distinguished from A. cingulatus in having superomarginal spines ( Fig. 9A, U ), and stands apart from A. brasiliensis in presenting three spines in the first subambulacral row ( Fig. 9F ) (versus two spines in A. brasiliensis ).

Astropecten aff. antillensis actually appears to be morphologically more closely related to A. antillensis , a species previously known from the Brazilian coasts only from Bahia ( John, 1948). However, the insular specimen differs from A. antillensis s. str. (cf., Clark & Downey, 1992) in having two prominent spines on the inner edge of the first pair of superomarginal plates, and one row of spines decreasing in size distally in the other plates ( Fig. 9A ) (versus prominent spines present on the inner edge of first 5–6 superomarginal plates, and a much smaller spine on the outer edge of all superomarginals in A. antillensis ); and two rows of subambulacral spines ( Fig. 9F ) (versus one row in A. antillensis ). However, the syntype ZMUC-AST-4-22 (R= 29 mm) of A. antillensis s. str. also shows a second row of subambulacral spines in some plates. The Trindade specimen and the Caribbean Colombian specimens assigned to A. antillensis by Benavides-Serrato et al. (2011) agree with one another in having inferomarginal plates projecting beyond the superomarginal ones. Conversely, in A. antillensis sensu Clark & Downey (1992) , the inferomarginals plates do not project beyond the superomarginals. According to Lütken (1859), morphology greatly varies over ontogeny in A. antillensis .

Astropecten aff. antillensis differs from its Brazilian congeners with superomarginal spines in that it has a large spine in the first subambulacral row. That spine is wider and longer than the proximal and distal spines and longer than the furrow spines ( Fig. 9F ). It further stands apart in having long, narrow arms and narrow disk; the inferomarginal plates usually have two ambital fringe spines (sometimes a much smaller one in the proximal region) ( Fig. 9A ). The fringe spines are about equal in length, or the distal spine is slightly longer. Conspicuous bare area in the center of the actinal surface of the inferomarginal plate ( Fig. 9G ). Paxillae with 1–5 central and about 12 peripherals spinelets. Three ambulacral spines truncated, the middle one larger than the lateral ones. No pedicellariae.

Figures

FIGURE 9. Astropecten aff. antillensis Lütken, 1859. A–Y. MZUSP 2090: A, B. Abactinal and actinal views. C. Paxillae. D. Madreporite. E. Mouth. F. Ambulacral spines. G. Squamules and spines, inferomarginal plate. H–Y. Scanning electron microscope. H–J. Superomarginal plates. K–M. Inferomarginal plates. N–P. Ambulacral plates. Q, R. Adambulacral plates. S, T. Haste, paxillae. U. Superomarginal spine. V, X. Inferomarginal spines. Z–Y. Furrow spines. Scale bars: A–B, 10 mm; C–D, G, 1 mm; E–F, 2 mm; H–J, N–R, U–X, Y, 200 μm; K–M, 300 μm; S, Z–W, 100 μm; T, 60 μm.