Antedon bifida moroccana (A.H. Clark, 1914 )

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 : 14-15

Antedon bifida moroccana (A.H. Clark, 1914)

( Fig. 4 )

Reports for the Azores:

Antedon sp.— $ Simroth 1888: 231;

Antedon rosacea Norman, 1865 — $ Barrois 1888: 32, 33, 115;? $ Koehler 1898: 3;

Antedon bifida ( Pennant, 1777) —A.H. Clark 1911: 38–39; $ Chapman 1955: 338; Tortonese 1965: 27; Nichols 1994: 113–134; Pereira 1997: 332; $ Morton et al. 1998: 150, fig. 7.5C; Micael & Costa 2010: 321; Micael et al. 2012: 3;

Antedon moroccana A.H. Clark, 1914: 307 ; Mortensen 1927a: 27;

Antedon bifida moroccana (A.H. Clark, 1914) — $ A.H. Clark & A.M. Clark 1967: 226–234, fig. 13c; $ Marques 1983: 1.

Type locality: Tangier, Morocco.

See: A.H. Clark & A.M. Clark (1967); Domenico et al. (2009).

Occurrence: Northeast Atlantic and Mediterranean Sea, from Morocco to west of Sierra Leone and Liberia, including the Azores, Madeira and Canaries (A.H. Clark & A.M. Clark 1967); the subspecies A. bifida bifida ( Pennant, 1777) is distributed further north in the Northeast Atlantic, from Portugal northwards to the British Islands (A.H. Clark & A.M. Clark 1967).

Depth: 0–200 m (A.H. Clark & A.M. Clark 1967); AZO: 3–60 (?130) m ( Koehler 1898, Marques 1983).

Habitat: present in waters with strong tidal currents and related upwelling phenomena ( Domenico et al. 2009); in shallow waters, it lives in relatively protected areas, clinging to rocks, algae or other sessile fauna ( Mortensen 1927a, Nichols 1994, Morton et al. 1998).

Larval stage: the females Antedon bifida brood the eggs, which produced a doliolaria larvae (non-feeding pelagic larvae, c. 5 days; Lahaye & Jangoux 1988; Nichols 1994).

Material examined: DBUA-ECH 071 (Piscina da Lagoa, Lagoa, SMG, AZO, c. 37°44’29”N, 25°34’27”W, 1996.07. 25, 12 m; 9 spms, AL = 46–74 mm); DBUA-ECH 072 (Baixa do Ouro, Caloura, SMG, AZO, c. 37°43’32”N, 25°32’47”W, 1996.12.05, 15 m; 3 spms, AL = 37–64 mm).

Description: disc naked, with ten slim pinnate arms about 37–74 mm in length; centrodorsal discoidal, bearing crowded and irregular cirrus sockets in two or three more or less alternating rows; cirri XXV–XXXIV, 13–16, from 7 to 11 mm long; in lateral view the cirri are twice as broad distally as proximally with the distal half strongly recurved; the cirrals in the outer part of the cirri are almost as broad as long dorsally, becoming terminally slightly longer, about one third again as long as broad; overall cirral outline not centrally constricted or appressed but strongly compressed laterally; conspicuous group of perisomic interradials in each interradius; division series short and well separated laterally; first pinnule (P1) composed for the most part of elongated segments, though a few of the basal segments may be shorter; P1 composed of 25–31 segments (c. 12 mm long) to about 19–20 segments (c. about 6–7 mm) in smaller specimens (arm length ± 46 mm); P1 is at least twice as long as the second pinnule (P2), which is similar in size to the third pinnule (P3), the first genital pinnule; gonads absent from the first two pinnules (P1 and P2) and confined to proximal half of the pinnule; the production of the distal ends of the segments of the proximal pinnules is marked; in ethanol, the anterior side is more or less cream colour with ambulacral grooves and pinnules dark reddish-brown or dark purple; posterior side uniformly light cream.

Remarks: the Antedon species present in the Atlantic show a great morphological variation resulting in somewhat overlapping interspecific diagnosing characters, which historically have puzzled taxonomists. A.H. Clark (1914) believed that the overall variation was essentially a result of different environmental settings. Later, A.H. Clark & A.M. Clark (1967) again questioned if the several forms of Antedon , from the west and east tropical Atlantic waters ( A. duebeni B̂hlsche, 1866 and A. hupferi Hartlaub, 1890 , respectively) and from the temperate and boreal Northeast Atlantic waters [ A. bifida subspecies and A. petasus ( D̹ben & Koren, 1846), respectively] could be all conspecific, a matter still to be settled.

The first report of an Antedon to the archipelago was made by Barrois (1888) under the name Antedon rosacea , a known synonymy of the European A. bifida . Simroth (1888) also listed an Antedon among the Azorean echinoderm fauna, but failed to assign it to a particular species. Koehler (1898) examined a very small and damaged specimen collected in the archipelago by Hirondelle at 130 m and commented that he could not ascertain if it belonged to Antedon rosacea . Chapman (1955) remarked that the animals from the Azores differ slightly from the typical A. bifida by having fewer segments in the first pinnule. A.H. Clark & A.M. Clark (1967) examined material from the Azores and concluded that the Antedon bifida present in the archipelago belonged to the subspecies moroccana . This subspecies differs essentially from the typical form by the overall aspect of the cirri segments. The first two pinnules (P1 and P2) seem also slightly smaller with fewer segments in A. b. moroccana . The overall cirrus shape exhibited by the Azorean material examined herein agrees with descriptions and illustrations of the moroccana form presented by A.H. Clark & A.M. Clark (1967) and by de Domenico et al. (2009). Nevertheless, smaller specimens showed slightly smaller P1 and P2, with fewer segments, similar to what was presented by A.H. Clark & A.M. Clark (1967) for Antedon bifida moroccana . These discrepancies were dismissed as size-related individual variations in view of the overall similarity with A. bifida particularly with the subspecies moroccana .

Figures

FIGURE 4. Antedon bifida moroccana (Clark, 1914) (DBUA-ECH 071). Dorsal view (A, C); ventral view (B, E); lateral view (D); detail of the disc, dorsal view (H), lateral view (E) and cirri (G).