Astropecten alligator Perrier, 1881

Gondim, Anne Isabelley, Christoffersen, Martin Lindsey & Pereira Dias, Thelma Lucia, 2014, Taxonomic guide and historical review of starfishes in northeastern Brazil (Echinodermata, Asteroidea), ZooKeys 449, pp. 1-56 : 6

Astropecten alligator Perrier, 1881 Figure 5a-d

Astropecten alligator Perrier, 1881: 30.

Astropecten nuttingi Verrill, 1915: 181, pl. 12, fig. 2e, pl. 21, figs 1-2.

Material examined.

Paraíba: 7°01'S; 34°41'05"W, 1 spec., UFPB/ECH.881, 13.II.1981, 24m.

Type locality.

Alligator Reef, Florida Keys, Florida ( Clark and Downey 1992).

Description.

Body flattened dorso-ventrally. Disk small, with five long and narrow arms (~4.93 mm) (Fig. 5a, b). Epiproctal cone pronounced (this region of the disk and the surrounding areas are inflated) (Fig. 5a). Abactinal surface flat and covered by small paxillae disposed in regular rows (Fig. 5a). Paxillae with a central spinelet and 8-10 (usually 9) thick, marginal spinelets with blunts extremities. Superomarginal figs short (~1.14 mm) and narrow (~1.59 mm), covered by short and blunt spinelets, giving a granulose appearance to animals. Each of these figs has an elongate, conical and pointed spine (Fig. 5a, c), which has the same length from the interbrachial area to the extremity of each arm. Inferomarginal figs with two long, flattened and pointed spines, placed in parallel to each other. These figs are also covered by short and narrow spinelets. Towards the mouth the inferomarginal figs are covered by many flattened and pointed spines, which become elongated at the margins. Adambulacral figs with three long, flattened adambulacral spines, placed in parallel to each other, the median one being slightly longer than the other two (Fig. 5d). There are three to four long and flattened subambulacral spines, the median of which is longer and wider than the other two.

Colour. Reddish-brown dorsally, with conspicuous dark bands along the center of each arm ( Clark and Downey 1992), or uniformly orange-red.

Distribution.

North Carolina, the Bahamas, Florida, Honduras, Nicaragua Colombia, and Brazil ( Verrill 1915, Gray et al. 1968, Clark and Downey 1992, Benavides-Serrato et al. 2005, 2011, Alvarado et al. 2008). In Brazil: Benavides-Serrato et al. (2005) cite its occurrence in the north of Brazil. This study expands the distribution southward to the State of Paraíba, being the first reference for the northeast region of Brazil. From 22 to 576 m in depth ( Benavides-Serrato et al. 2011), most frequent between 22 and 114 m ( Clark and Downey 1992).

Remarks.

Astropecten alligator difers from the remaining species in the genus recorded for Brazil for presenting a single, elongate, erect conical spine on all the superomarginal figs. This character is present in both juvenile and adult individuals (dd = 41.0 mm). For a long time it was believed that Perrier (1881) had described Astropecten alligator based on a juvenile specimen and the recognition of this species remained uncertain. Clark and Downey (1992) analised the type material of Astropecten alligator . They were able to validate the species and consider Astropecten nuttingi Verrill, 1915 a junior synonym of this taxon. In a molecular phylogenetic analysis of Astropecten , Zulliger and Lessios (2010) concluded that Astropecten alligator and Astropecten americanus probably belong to the same species and that the species needs to be extensively revised.

Ecological notes.

Usually inhabits muddy environments, but may also be found associated to communities of azooxanthelate corals ( Benavides-Serrato et al. 2011). It is common along the coast of Florida ( Clark and Downey 1992), but for a long time it has been erroneously cited there as Astropecten nuttingi . In other areas Astropecten alligator is a rare species, being little cited in the literature.