Astropecten, Gray, 1840

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 : 18

Taxonomic remarks of the genus Astropecten

As noted by Cobb et al. (2019), telling some of the Astropecten species apart is not trivial. We found several instances of misidentification in prior work from Northeastern Brazil and we hope that the present work will reduce errors in future studies. Phylogenetic relationships between some species of Brazilian Astropecten were addressed by Zulliger & Lessios (2010) and Cobb et al. (2019). Their molecular cladograms indicate that A. antillensis is more closely related to A. articulatus than to A. cingulatus . The relationship between these species and A. marginatus is uncertain as this species could be equally related to A. antillensis , A. articulatus and A. cingulatus or most closely related to A. cingulatus ( Zulliger & Lessios, 2010) . Astropencten brasiliensis was not included in these studies.

Astropecten acutiradiatus differs from A. alligator by having an enlarged spine in the first subambulacral row (vs. three (sub)equal spines); from A. antillensis by having an enlarged distal spine in the first subambulacral row (vs. enlarged central spine); from A. articulatus by having clavate paxillar spinelets (vs. paxillar spinelets granulose); from A. brasiliensis brasiliensis and A. duplicatus by the absence of enlarged spines on the distal superomarginal plates (vs. presence of enlarged spines on the distal superomarginal plates); from A. cingulatus and A. marginatus by having spines on the proximal superomarginal plates (vs. superomarginal spines absent).

Astropecten antillensis differs from A. acutiradiatus , A. articulatus , A. brasiliensis brasiliensis and A. duplicatus by having an enlarged central spine in the first subambulacral row (vs. enlarged distal spine); from A. alligator by having an enlarged spine in the first subambulacral row (vs. three (sub)equal spines); from A. cingulatus and A. marginatus by having spines on the superomarginal plates (vs. superomarginal spines absent). Astropecten antillensis also differs from A. brasiliensis brasiliensis because its inner superomarginal (not the first pair) spine is smaller than the outer spine (vs. inner spine larger than outer spine).

Astropecten brasiliensis brasiliensis differs from A. marginatus and A. cingulatus by having superomarginal spines (vs. superomarginal spines absent); from A. articulatus and A. duplicatus by having subambulacral spines with blunt tips (vs. spines truncated in two), and inferomarginal fringe spines oblique (vs. inferomarginal fringe spines horizontal); and from A. alligator by having an enlarged distal spine in the first subambulacral row (vs. (sub)equal spines).

Astropecten cingulatus differs from A. marginatus by having inferomarginal plates densely covered with overlapping squamules and spines (vs. inferomarginal plates bare or with sparse, widely spaced squamules), and these two species differ from the other Brazilian Astropecten by having no spines on the superomarginal plates (vs. spines present).