Echinus melo Lamarck 1816

Echinus melo Lamarck, 1816

(Fig. 24)

Echinus melo Lamarck, 1816 — $ Koehler 1909: 232; Koehler 1921b: 118–119, fig. 79; Nobre 1938: 115–116, fig. 52; Mortensen 1943a: 53–57, pl. 9, figs. 2, pl. 13, figs. 2, pl. 17, fig. 1; Harvey 1956: 64; Tortonese 1965: 332–333, fig. 157B; Marques 1980: 105; Pereira 1997: 334; García-Diez et al. 2005: 50; Mironov 2006: 110; Schultz 2006: 190, figs. 252–253; Micael & Costa 2010: 323; Micael et al. 2012: 4;

p.p. Echinus acutus — $ Wisshak et al. 2010: 2382, fig. 2L.

See: Mortensen (1943a); Mironov (2006); Schultz (2006); Minin (2012).

Occurrence: Mediterranean Sea and northeast Atlantic, from the British Islands (Mortensen 1927a) to the northwest African coasts (Mortensen 1925), including the Azores (Koehler 1909), Canary and Cape Verde archipelagos (Agassiz 1872) and the Josephine, Ampere and Meteor seamounts (Mironov 2006).

Depth: 25– 1,100 m (Mortensen 1943a); AZO: 200–475 m (Koehler 1909, herein).

Habitat: muddy bottoms to hard substrates (Koehler 1909, 1921b).

Material examined: EMEPC L09D17B1 (E of TER, AZO, 38°39’52”N, 26°51’22”W, 2009.09. 30, 475 m; 1 spm, D = 185 mm).

Description: test globular, slightly pentagonal with a height about of 75%D; Apical disc dicyclic, about 12%D. Periproctal plates with none to two spines. Madreporite enlarged. Gonopores open. Ambulacra about half the width of the interambulacra; in general, every ambulacral plate and every second interambulacral plate aborally bearing a primary tubercle; ambulacral plating trigeminate with pore-pairs in arcs of three at a distance from the edge of ambulacra. Peristome slightly larger than the apical disc (17%D). Primary spines short (10%D) and slender; on the oral side primary spines somewhat flattened with blunt tip; each peristomal plate with a small spine. Valves of globiferous pedicellaria with one short lateral tooth on each side below the end tooth; basal part with round angles and as long as the blade. Large form of tridentate pedicellariae (up to 3 mm) with straight, narrow valves (edges with numerous small serrations). Small form with slender, slightly curved valves. Valves of ophicephalous pedicellariae constricted in the middle and with round edges armed with minute teeth. Colour: test cream white; pore areas brown; primary spines white to green with white tips; secondary spines white; madreporite ochre. For some unknown reason the preserved specimen became tinged by a light pink hue.

Remarks: Echinus melo can be easily identified from other echinid species (except Gracilechinus acutus) known to occur in the Azores by its spherical large test reaching a maximum diameter of 170 mm (Mironov 2006) to 185 mm. Another easy recognizable character is the large distance between the pore zone and the adradial suture. Echinus melo was previously documented for the Azores by a single small specimen reported by Koehler (1909) based on the material collected in the Princesse Alice Bank (Princesse Alice, sta 899: 37°57’00”N, 29°14’45”W, 200 m). The new record further substantiates the presence of this species in the Azorean deep waters. Also, during EMEPC cruise (2009) in the Azores, an animal believed to belong to this species was captured on video east of Terceira Island at similar depths (38°47'50"N, 27°28'57"W, 455 m, Fig. 24E). See also remarks below under Gracilechinus acutus.