Clypeaster subdepressus ( Gray, 1825 )

Gondim, Anne Isabelley, Moura, Rafael Bendayan De, Christoffersen, Martin Lindsey & Dias, Thelma Lúcia Pereira, 2018, Taxonomic guide and historical review of echinoids (Echinodermata: Echinoidea) from northeastern Brazil, Zootaxa 4529 (1), pp. 1-72 : 29-30

Clypeaster subdepressus ( Gray, 1825)

Figure 10 A–H

Echinanthus subdepressus Gray, 1825: 427 .

Clypeaster subdepressus L. Agassiz, 1836: 20 .― Rathbun, 1879: 144.― Krau, 1956: 415 –416, figs 5–10, 13, 15, 17 and 19.― Tommasi, 1957: 21; 1959: 602.― Alves & Cerqueira, 2000: 547.― Ventura et al., 2007b: 279, tab.11.2; 2014: 65.– Xavier, 2010: 75.–Ventura, 2013: 106, fig. 122a, b.

Stolonoclypus subdepressus Lambert & Thiéry, 1914: 301 .

Clypeaster (Stolonoclypus) subdepressus Mortensen, 1948a: 112 –116, pl. 23, figs 1–3, pl. 24, fig. 3, pl. 25, fig. 6, pl. 26, figs 1, 6, pl. 27, fig. 4, pl. 45, figs 4, 11, 14, 15.― Tommasi, 1957: 30 –31, figs 22―24, pl. 2, figs 3―4; 1964: 84–87; 1966a: 24.― Cherbonnier, 1959: 368 –370.― Brito, 1962: 6; 1968: 24–25, pl. 12, fig. 3.― Magalhães et al., 2005: 63.

Clypeaster (Stolonoclypus) subdepressus lobatus Bernasconi, 1956: 35 .― Brito, 1960a: 3 ―4; 1968: 25–26.― Tommasi, 1964: 84 –87; 1966b: 240–241.

Clypeaster subdepressus subdepressus Tommasi, 1959: 602 , 603.– Ventura et al., 2007b: 290, app. 11.1.

Clypeaster latissimus Krau, 1956: 413 –427.

Clypeaster (Stolonoclypus) subdepressus subdepressus Brito, 1960a: 3 , pl. 1d.― Tommasi, 1972: 31.

Material examined. Bahia: 1 spm, Salvador, 14.IX.1997 [UFBA00072]; 1 spm, 12°54′S 28°29′W, Salvador, 22.VIII.1993 [UFBA00461].

Description. Test large (TL = 139 mm; TW = 118 mm), oval, with rounded margin, uniformly covered by short, thin spines, petaloid region slightly inflated ( Fig. 10 A–C). Apical system central, monobasal, with five gonopores ( Fig. 10F ). Petaloid large, slightly longer than 50% of test ( Fig. 10A, D ). Petals large, leaf-shaped ( Fig. 10A, D ). Paired petals nearly closed distally ( Fig. 10A, D ). Lunule lacking. Aboral primary spines long, slightly club-shaped. Oral primary spines long, terminating in a small hyaline point. Tubercles perforate. Areoles of aboral primary tubercles uniform in size. Oral surface flat, slightly concave around peristome ( Fig. 10B, E ). Peristome circular, central ( Fig. 10B, E, G ). Food grooves unbranched, fairly deep, not reaching ambitus ( Fig. 10E ). Periproct oral, towards posterior margin, located between third and fifth pairs of post-basicoronal interambulacral plates ( Fig. 10B, E ). Periproctal membrane densely covered by spines, with some small bivalved triphyllous pedicellariae.

Pedicellariae. Tridentate pedicellariae more abundant in areas close to peristome and to food grooves. Ophicephalous pedicellariae more abundant on margins and triphyllous pedicellariae distributed over entire test. Tridentate pedicellariae with short stalk and neck. Valves long, narrow, with denticulate margin and slightly enlarged tip. Ophicephalous pedicellariae short, without a neck. Valves narrow, with enlarged tips, and foramen (sensu Coppard et al. 2012) denticulate ( Fig. 10H ). Bivalved triphyllous pedicellariae small, with long neck and small head. Valves rounded. Some quadridentate pedicellariae were also observed.

Colour. Colour in life yellowish, reddish, very deep brown ( Mortensen 1948a), or olive green ( Tommasi 1966a). Spines brownish-green. Preserved specimens are light brownish ( Mortensen 1948a). Naked test white.

Distribution. Florida, North Carolina, Mexico, Cuba, Jamaica, Dominican Republic, Panama, Colombia, Venezuela, and Brazil ( Alvarado 2011; Tommasi 1966a). In Brazil from BA, RJ, SP and SC ( Tommasi 1966b; Alves & Cerqueira 2000; Magalhães et al. 2005; Xavier 2010). From 5 to 210 m, more common between 5 and 50 m ( Serafy 1979; Hendler et al. 1995; Laguarda-Figueras et al. 2005a).

Remarks. Presently 49 extant species of Clypeaster are known, making it the most speciose extant echinoid genus ( Mihaljević et al. 2011). In Brazil, there are records of five species [ C. rosaceus ( Linnaeus, 1758) , C. subdepressus , C. lamprus H.L. Clark, 1914 , C. aloysioi ( Brito, 1959) and C. oliverai Krau, 1952 ]. Both C. aloysioi and C. oliverai are endemic to southeastern Brazil. Clypeaster aloysioi differs from C. subdepressus in its pentagonal test, and narrower and more widely open petals. Clypeaster oliverai differs by having a large petaloid occupying almost the entire aboral surface, and slightly conical test in lateral view. Clypeaster lamprus differs by having a brown-reddish colour, a slightly pentagonal test with thick borders, and spatulate oral spines. Mortensen (1948a) subdivided Clypeaster into ten subgenera. In a study on the architecture of the test Mihaljević et al. (2011) suggested that the subgenera proposed by Mortensen (1948a) do not represent clades. Thus, Mihaljević et al. (2011) agree with Serafy (1970), Mooi (1989) and Kroh & Mooi (2016) in not adopting any subgenera, although recognizing considerable heterogeneity among the species. In the present study, only two adults were examined, in which no morphological variations were observed. Tommasi (1964) gave a good discussion on the possible morphological variations found in C. subdepressus .

Ecological notes. This species lives in sandy substrates or sediments formed by shell fragments. It can be found in seagrass and on sandy bottoms near coral reefs (del Valle García et al. 2005). Telford et al. (1978) studied the feeding activities of C. subdepressus and established that individuals select particles above 400 µm in diameter for ingestion. According to Gladfelter (1978), the gastropod Cassis tuberosa is a common predator of this species. Clypeaster subdepressus is common along the littoral region of southeastern Brazil, but appears to be rare in northeastern Brazil.

Figures

FIGURE 10. Morphological characters of Clypeaster subdepressus (UFBA00072). (A) Aboral view; (B) Oral view; (C) Lateral view; (D) Aboral view of naked test; (E) Oral view of naked test; (F) Madreporic plate; (G) Peristome and basicoronal plates; (H) Valve of ophicephalous pedicellariae.