Schizaster floridiensis

Schizaster floridiensis (Kier & Grant, 1965)

Figure 9 E–K

Schizaster (Paraster) floridiensis Kier & Grant, 1965: 50 –54, pl. 13, figs 4–6, pl. 14, figs 1–9. Paraster floridensis Chesher, 1966: 1 –19, figs 1–6.― Manso, 2004: 20 –21, fig. 1.― Magalhães et al., 2005: 63.― Oliveira et al., 2010: 11.

Material examined. Photographic record.

Description (modified from Chesher 1966, Manso 2004 and Smith & Stockley 2005). Test small, fragile, subglobular, almost as broad as long, slightly larger than high, and vertically truncate posteriorly (Fig. 9 F–G). Test covered by slender, hyaline, and and often curved spines (Fig. 9 F–G), with slightly spatulate tips. Apical system ethmolytic, with four large gonopores. Anterior genital pores about half the size of posterior pores. Anterior paired petals (ambulacra II and IV) slightly curved and two to three times longer than posterior petals (ambulacra I and V) (Fig. 9E). Ambulacrum III forms a strongly sunken furrow extending toward peristome (Fig. 9E) that lacks primary spines. Peripetalous and lateroanal fascioles well-developed (Fig. 9G). Peripetalous fasciole crosses ambulacrum III (Fig. 8E), and anteriorly over plates 2.a.4 and 2.b.4 [4, 4:: 5+6/7, 6(7):: 10]. Lateroanal fasciole begins close to ambulacra II and IV and extends towards of periproct [–, –:: 5, 4(5):: 5+4] (Fig. 9E, G). Plates of ambulacra I and V without spines (Fig. 9F). Peristome narrow, three times as broad as long (Fig. 9F). Labrum extends to second plate of interambulacrum 5. Plastron amphisternous, covered by long, narrow spines, spatulate (Fig. 9F). Periproct large, oval, located almost vertically.

Pedicellariae. Globiferous and tridentate pedicellariae distributed over entire test. Rostrate pedicellariae found near periproct (Fig. 9H). Globiferous pedicellariae with stalk, without a neck, valves with two end teeth (Fig. 9J, K). Tridentate pedicellariae with valve having an enlarged and serrate tip (Fig. 9I). Valve of rostrate pedicellariae with a narrow, serrate and spatulate blade (Chesher 1966). Chesher (1966) provides illustrations of all the pedicellariae of this species (Fig. 9 H–K).

Colour. Test light pink to yellowish (Hendler et al. 1995). The fascioles and tube feet of petals red, tube feet of anterior groove yellow-orange (Hendler et al. 1995; Manso 2004).

Distribution. Gulf of Mexico, Florida, Bahamas, Bermudas, Belize, Puerto Rico, Honduras, Dominican Republic, Panama, Venezuela, and Brazil (Hendler et al. 1995; Lessios 1998; Manso 2004; Alvarado 2011; Rodríguez-Barreras et al. 2013; Solís-Marín et al. 2013). In Brazil, from BA and RJ (Manso 2004; Oliveira et al. 2010). From depths of 2 to 45 m (Manso 2004).

Remarks. The genus Schizaster contains nine extant species, of which only three are recorded from the tropical Atlantic [S. doederleini (Chesher, 1972), S. orbignyanus A. Agassiz, 1880 and S. floridiensis]. The first two range from the Gulf of Mexico to Venezuela and the latter has Rio de Janeiro as its southern limit. Schizaster floridiensis differs from S. doederleini by its rounded test, presence of less numerous pore-pairs in petal III, a shorter distance from the periproct to the lateroanal fasciole, and a larger petaloid. Schizaster floridiensis also differs from its congener S. orbignyanus, which has two genital pores and ambulacrum III more depressed and larger. According to Chesher (1966), details are lacking for several important taxonomic characters in the original description given by Kier & Grant (1965). Thus, Chesher (1966) redescribed the species and furnished an excellent discussion on variations found in S. floridiensis.

Ecological notes. This species lives burrowed in sandy and muddy sediments, at depths of about 25 cm into the sediment (Chesher 1966). Schizaster floridiensis frequently occurs in association with S. doederleini and other fragile, burrowing spatangoids (Hendler et al. 1995). Manso (2004) recorded S. floridiensis together with the ophiuroid Amphioplus camamuensis Manso, 2004, from Baía de Camamu (Bahia).