Echinocardium cordatum ( Pennant, 1777 )

Madeira, Patrícia, Kroh, Andreas, Cordeiro, Ricardo, De, António M., Martins, Frias & Ávila, Sérgio P., 2019, The Echinoderm Fauna of the Azores (NE Atlantic Ocean), Zootaxa 4639 (1), pp. 1-231 : 126

Echinocardium cordatum ( Pennant, 1777)

( Fig. 30A )

Reports for the Azores:

Echinocardium flavescens (M̹ller, 1776)—? $ Barrois 1888: 110 [early juveniles, identification doubtful];

Echinocardium cordatum ( Pennant, 1777) — $ Marques 1983: 6; $ Pereira 1997: 334; Wirtz & Debelius 2003: 261; Micael & Costa 2010: 323; Madeira et al. 2011: 257; Micael et al. 2012: 4.

See: Mortensen (1927a: 331–334, figs. 194.1–2); Higgins (1974, 1975); De Ridder et al. (1987); Schultz (2006: 411, fig. 772).

Occurrence: antitropical, present in the W Pacific, E Atlantic and Mediterranean Sea ( Egea et al. 2016); in the east from Scandinavia and the British Isles to Morocco (H.L. Clark 1925, Mortensen 1925), including the Azores ( Marques 1983), Madeira ( Jesus & Abreu 1998) and Canaries ( Hernández et al. 2013); also present in South Africa ( Mortensen 1951b).

Depth: 0–230 m ( Mortensen 1927a); AZO: 15–20 m (herein).

Habitat: buried in mud, sand to gravel ( Mortensen 1927a, Higgins 1974).

Larval stage: planktotrophic (31–35 days; Schipper et al. 2008);

Fossil record: fossil remains belonging to the genus Echinocardium were documented in the Pliocene fossiliferous outcrops of Santa Maria ( Madeira et al. 2011).

Material examined: DBUA-ECH 083 (Baia do Rosto do C„o, S„o Roque, SMG, AZO, c. 37°44’37”N, 25°38’19”W, 1990.07. 5, 15–20 m; 1 broken spm; TL = 38 mm);

Description: test very fragile (oral side missing) with a subrounded (greatest weight = TL). Anterior end truncated in lateral view; frontal ambulacrum sunken. Larger tubercles mostly absent, except for the edge of the anterior ambulacrum. Apical disc posterior with four genital pores. Internal fasciole shield-shaped, longer than wide (width = 42% length), almost half of the test length; 35–36 pores on each side of ambulacrum III within the fasciole, arranged in the following manner: small pores aligned proximally in a single series relatively; in the mid-section larger pores somewhat transversely elongated and more crowded forming an irregular biserial arrangement (area of largest weigh of the fasciole); at the anterior end circular pores more widely spaced, forming again a single series. Specialized penicillate tube feet present. Rows of the pair petals somewhat convergent and depressed; petal IV and V with 9(IVa)–14(IVb) and 12(Vb)–11(Va) pore pairs, respectively. Periproct round and truncated. Anal fasciole expanding along the sides of the periproct onto the aboral side. Spines relatively uniform through the aboral region with the exception of elongated spines of the frontal ambulacrum forming an apical tuft. No pedicellaria were found, except for a few small tridentate (=200 μm) with leafshaped valves with irregularly serrate edge. Colour: naked test cream, spines light brown and brown tube feet.

Remarks: Marques (1983) was the first to report Echinocardium cordatum from the archipelago. We have not found the specimen(s) in the Vasco Marques collection at the Bocage Museum. Nevertheless, later Wirtz & Debelius (2003) published a photograph portraying an E. cordatum in situ in Faial Island. Unfortunately, none of the authors have specified at which depth this species seems to occur in the archipelago (see below remarks under E. flavescens ).

The specimen housed in DBUA-ECH collection was rather damaged, lacking the entire oral area. Regardless, this specimen presents the typical double arrangement of the pores of ambulacrum III of E. cordatum . In contrast, the specimen lacks many features expected in a typical E. cordatum , having a weakly sunken ambulacrum III ab- orally. On the other hand, E. cordatum is characterised by a high degree of morphological variation and the observed departure from the norm is well inside the documented variability of this species (see Higgins 1974, 1975). Unfortunately, only one type of pedicellariae was found. The small tridentate pedicellariae are similar to what Mortensen (1907) described for E. cordatum . However, this type of pedicellariae is not diagnostic, and similar morphologies can be found in other species known from the NE Atlantic such E. flavescens ( Mortensen 1907) .

Figures

FIGURE 30. Echinocardium cordatum (Pennant, 1777) (DBUA-ECH 083: A) and Echinocardium sp. (DBUA-ECH 084: B–D; DBUA-ECH 278: E–H). Apical view (A, B, E); oral view (C, F); posterior view (G); lateral view (D, H).