Ophiura (Dictenophiura) carnea carnea Lütken, 1858

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 : 54-56

Ophiura (Dictenophiura) carnea carnea Lütken, 1858

( Fig. 11 )

Reports for the Azores:

Ophioglypha carnea ( L̹tken, 1858)— $ Koehler 1909: 147–148;

Ophiura carnea L̹tken, 1858 — Farran 1913: 29–30, figs. 2–3; Koehler 1923: 14, 1924: 314–315; García-Diez et al. 2005: 49; Dictenophiura carnea ( L̹tken, 1858)— Tortonese 1965: 267;

Ophiura carnea Sars, 1861 — Mortensen 1927a: 243, figs. 131.3–4

Type locality: Bergen, Norway.

See: L̹tken (1858: 41, pl. 1, figs. 6a–b); Farran (1913); Madsen (1970: 233–234, fig. 46); Paterson (1985: 117, fig. 42).

Occurrence: Northeast Atlantic and Mediterranean Sea, from Reykjanes Ridge (south of Iceland; Copley et al. 1996), Scandinavia and Faeroe Islands to Senegal, including the Azores and? Cape Verde archipelagos ( Koehler 1923, Mortensen 1927a, 1933a) and Gorringe Seamount ( Pérès 1964); the subspecies O. carnea skoogi ( Koehler, 1923) is known from tropical West Africa, from Dakar to Angola ( Madsen 1970).

Depth: 14– 2,857 m ( Paterson 1985, herein); AZO: 14–599 m ( Koehler 1909, herein).

Habitat: soft (mud, sand, gravel, detritic) to hard substrates ( Cherbonnier 1969, 1970).

Larval stage: planktotrophic ( McEdward & Miner 2001).

Material examined: DBUA-ECH 065 (Vila Franca do Campo, SMG, AZO, c. 37°42’50”N, 25°25’58”W, 1991.08.03, 70–80 m; 4 spms, DD = 5–6 mm); DBUA-ECH 066 (Água d’Alto, SMG, AZO, c. 37°42’55”N, 25°28’27”W, 1991.07.30; 4 spms, DD = 5 mm); DBUA-ECH 068 (off Ribeira das Tainhas, Vila Franca do Campo, SMG, AZO, 37°42’16”N, 25°24’45”W, 2006.07. 21, 72 m; 2 spms, DD = 3–4 mm); DBUA-ECH 134 (Vila Franca do Campo, SMG, AZO, 37°42’43”N, 25°21’33”W, 2006.07. 26, 38 m; 4 spms, DD = 3–5 mm); DBUA-ECH 135 (Vila Franca do Campo, SMG, AZO, 37°41’39”N. 25°27’11”W, 2006.07. 21, 95–121 m; 1 spm, DD = 4 mm); DBUA-ECH 136 (off Praia de Água d’Alto, SMG, AZO, 37°42’24”N, 25°28’59”W, 2006.07. 26, 66 m; 2 spms, DD = 4–5 mm); DBUA-ECH 137 (off Ribeira das Tainhas, SMG, AZO, 37°41’57”N, 25°25’08”W, 2006.07. 24, 144– 198 m; 1 spm, DD = 6 mm); DBUA-ECH 332 (off Praia da Vinha da Areia, SMG, AZO, 37°42’15”N, 25°24’28”W, 2006.07. 21, 14 m; 1 spm, DD = 4 mm); DBUA-ECH 333 (off Ponta Garça, SMG, AZO, 37°42’01”N, 25°23’07”W, 2006.09.05, 318 m; 1 spm, DD = 4 mm); DBUA-ECH 335 (off Vila Franca do Campo, SMG, AZO, 37°41’52”N, 25°23’13”W, 2006.07. 21, 46–47 m; 1 spm, DD = 3 mm).

Description: disc round to subpentagonal, high with almost vertical sides; five short arms mostly broken off at the tip, about twice the DD; disc scales rather coarse and naked, with distinct centrodorsal and primary plates. Radial shields rounded to almost teardrop-shaped in larger specimens (length> breadth), contiguous distally, about one third of the disc radius in length. Arm combs prominent, almost vertical, extending up towards the dorsal surface of the disc; outer comb with about 10 to 12 conical and slightly rounded spinelets; inner comb with smaller and pointed spinelets. Innermost dorsal plate with a distinct groove. One pointed apical papilla flanked on each side by one triangular and two block-like oral papillae. Adoral shields narrow, slightly curved in appearance. Oral shields rounded pentagonal somewhat elongated (length> breadth) about one third to one half of the disc radius, with an obtuse proximal angle and a convex distal edge. Genital papillae small, pointed. Second oral tentacle slit, with three to four rounded tentacle scales on each side increasing to five to six in the larger specimens (DD = 6 mm). Dorsal arm plates fan-shaped, distal edge with a weak point, contiguous only on the first 2–3 proximal arm segments and swollen in profile. First ventral arm plate triangular to trapezoidal; subsequent plates become more rounded with an obtuse proximal angle and a rounded distal edge; they are separated from one another. First proximal tentacle pores large with one larger rounded tentacle scale opposing one to two smaller ones; in largest specimens (DD = 6 mm), one to two extra scales are also present, summing the total tentacle scales per pore to 4–5; the number of tentacle scales is reduced to one by the fourth proximal arm segment. Lateral arm plates swollen, with three relatively small arm spines of about the same size and evenly spaced, distally decreasing progressively in size. Colour (in ethanol): most specimens presented a more or less uniform white colour pattern, with dorsal side of the disc slightly darker with clear white radial shields; the original colour seems better preserved in one specimen (DBUA-ECH 332, Fig. 11 ), having the dorsal surface of the disc light brown and the arms banded light pink, white and light brown; ventral surface uniformly white or cream.

Remarks: the examined specimens share many diagnosing characters of O. carnea , distinct from the close resembling O. albida and O. imprudens : a thick almost vertical disc; comparatively small arms; well developed almost vertical arm combs; a distinct longitudinal furrow in the inner-most dorsal arm-plate; arm plates with overall swollen appearance; small rounded radial shields and somewhat longer oral shields. The examined specimens did not present the arm spines arranged as described by Paterson (1985) in O. carnea (i.e., two adjacent to the tentacle pore and another towards the dorsal surface). However, this appears to be a variable character in this species, and animals of this species may present arm spines arranged in an evenly manner (e. g., Koehler 1898, Mortensen 1927 a, Gl̹ck et al. 2012). Previously, O. carnea was known in the Azores based on a single specimen collected by Princesse Alice (sta 866: 38°52’50”N, 27°23’05”W, 599 m; Koehler 1909).

H.L. Clark (1923: 361) selected O. carnea as the genotype of Dictenophiura , a genus characterised by a longitudinal furrow dividing the inner-most dorsal plate. Madsen (1970: 234) downgraded Dictenophiura to a subgenus of Ophiura , on the basis that this is not a constant character in O. carnea , occasionally absent in larger specimens (see also Mortensen 1933a: 82). In view of this, we agree with Paterson (1985: 118, table 3), that this species closely resembles O. imprudens . In the absence of a medium furrow in the inner-most dorsal plate, O. carnea differs only slightly from O. imprudens : by the shape/size of the radial and mouth plates. Also, the arm combs in O. imprudens appear not to be prominent as in O. carnea . The former species is known by very little material, a total of seven reported specimens ( Koehler 1906 a, Gage et al. 1985). As more material becomes available, it will be necessary to re-address O. imprudens specific status in relation to O. carnea . Additionally, the subspecies African O. carnea skoogi is distinguished from O. carnea carnea by relatively more swollen dorsal and lateral arm plates ( Mortensen 1936). We believe that our material belongs to the NE Atlantic variety despite the remarks by Madsen (1970: 234), who observed that O. carnea skoogi can only be diagnosed with certainty in fully grown animals (6–7 mm disc diameter).

Koehler (1923) included Cape Verde in the geographical distribution of O. carnea , which was repeated by subsequent references (e.g., Koehler 1924, Mortensen 1927a, 1936, Tortonese 1965, Madsen 1970). We could not trace the original material on which Koehler (1923) based his record, though the occurrence of this species in Cape Verde is not unlikely considering the wide distribution of O. carnea in East Atlantic waters.

Figures

FIGURE 11. Ophiura (Dictenophiura) carnea carnea Lütken, 1858 (DBUA-ECH 332). Dorsal view (A); ventral view (B); detail of the disc and arm, dorsal view (C) and ventral view (D).