Hacelia attenuata Gray, 1840

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 : 91-92

Hacelia attenuata Gray, 1840

( Fig. 18 )

Reports for the Azores:

Ophidiaster attenuatus ( Gray, 1840) — $ Sladen 1889: 403;

Hacelia attenuata ( Gray, 1840) — $ Koehler 1909: 89, pl. 2, fig. 1, pl. 20, fig. 5; Koehler 1914b: 274, 1924: 165; H.L. Clark 1921a: 87; Koehler 1921b: 40, fig. 29; $ Tortonese 1965: 164–166, fig. 78; $ Marques 1983: 2, fig. 1; A.M. Clark & Downey 1992: 272–273; $ Wirtz & Vader 1996: 17–22; Pereira 1997: 335; $ Morton et al. 1998: 66, 76, figs. 3.6O, 4.2A; García-Diez et al. 2005: 47; Micael & Costa 2010: 322; Micael et al. 2012: 6.

See: A.M. Clark & Downey (1992).

Occurrence: Mediterranean Sea and Northeast Atlantic, in the Gulf of Guinea (A.M. Clark & Downey 1992), the Azores ( Marques 1983), Canaries ( Bacallado et al. 1985) and Cape Verde ( Nataf & Cherbonnier 1975).

Depth: 1–190 m ( Koukouras et al. 2007); AZO: 1–165(?823) m ( Sladen 1889, Morton et al. 1998); in the Azores this species tends to be particularly abundant at depths deeper than 40 m ( Marques 1983).

Habitat: hard substrates to biogenic detritus, gravel, sand and shells to sandy silt ( Koehler 1909, Koukouras et al. 2007); also associated with deep-water coral communities of Dendrophyllia ramea ( Linnaeus, 1758) ( Bacallado et al. 1985) .

Material examined: DBUA-ECH 074 (Baixa do Ouro, Caloura, SMG, AZO, c. 37°43’32”N, 25°32’47”W, 1996.12.05, 15 m; 3 spms, R = 75–99 mm, r = 13–17 mm).

Description: disc of moderate size, five arms, long, rounded abactinally and flattened actinally, tapering gently to rather acute tip. Body covered with densely packed granules. Abactinal plates small, flat, arranged in regular longitudinal rows. Each of the ten pore areas containing up to 32 papular pores; Lowermost row nearest adambulacrals with double pore areas but each containing less than half the number of pores. Both marginal series more distinct distally; last few plates in each series enlarged, tumid and bare (as are the last few carinal plates). Three rows of actinal plates proximally, the outermost one not extending to end of arm. Adambulacral plates with two blunt, flattened, parallel furrow spines, proximal one larger; one large, blunt, slightly flattened subambulacral spine. No pedicellaria. Colour (in ethanol) white.

Remarks: Hacelia attenuata can be easily distinguished from the only other ophidiasterid known from the shallow waters of the Azores (± 50 m), Ophidiaster ophidianus ( Lamarck, 1816) by the overall shape of the body whereas in the first species the arms tend to be flattened ventrally and in the second species tubular. Also in H. attenuata the number of longitudinal rows of papular areas tends to be higher than in O. ophidianus , ten and eight respectively. Regardless, these two sea stars tend to be bathymetrically separate as O. ophidianus occurs typically in the first few meters and H. attenuata becomes abundant in waters below 40 m. Also, H. attenuata can be easily distinguished from H. superba the only other species of genus Hacelia known to occur in the Atlantic, as the latter has typically less pores in each of the papular areas (8–22), thicker broad-based arms and an ridged abactinal surface due to its the tumid plates and sunken popular areas (A.M. Clark & Downey 1992). See below remarks under O. ophidianus .

Sladen (1889) reported Hacelia attenuata (= Ophidiaster attenuatus ) among the material collected by H.M.S. Challenger in the Azores, presumably at a depth of 823 m (sta 75: 38°38’00”N, 28°28’30”W), which is notably deep for a shallow-water species. Moreover, this species was identified together with other species that are generally found at depths lower than 150 m, suggesting a misprint in the dredge depth. It is very likely that the maximum reported depth lay somewhere between 92–165 m (see remarks under Astropecten hermatophilus ).

Figures

FIGURE 18. Hacelia attenuata Gray, 1840 (DBUA-ECH 074). Dorsal view (A); ventral view (B); detail of the arm and disc, dorsal view (C), ventral view (D).