Histocidaris purpurata ? (Thomson 1872

Histocidaris purpurata ? (Thomson, 1872b) Reports for the Azores:

Porocidaris purpurata Thomson, 1872 b—? $ Pérès 1992: 252.

Type locality: about 100 miles to the north of the Hebrides.

See: Mortensen (1928: 104–107, pl. 1, fig. 6, pl. 3, figs. 3–5, as Poriocidaris purpurata); Gage et al. (1985: 179 as Poriocidaris purpurata).

Occurrence: North Atlantic; in the East from southern Iceland south to the Canaries and Western Sahara (Koehler 1909, Mortensen 1927b, 1928); in the west known only from the Caribbean (Phelan 1970); reported elsewhere in South African waters (Filander et al. 2019).

Depth: 300– 1,800 m (Gage et al. 1985); AZO:? 800 m (Pérès 1992).

Habitat: soft sediments, from sandy mud to muddy bottoms (Koehler 1909, Mortensen 1928); gut contents revealed bottom material and fragments of crustaceans (Mortensen 1928).

Larval stage: lecithotrophic (Emlet 1995).

Remarks: on a dive made by the bathyscaphe Archimède in the Azores, Pérès (1992) reported to have observed animals of Histocidaris purpurata with their typical long spines with alternating bands of purple and violet. This cidaroid species has a wide distribution in the Atlantic, thus its report in the Azores could be easily considered as an intermediate location between its distribution in the Caribbean and the European or NW Africa records. However, no specimen was collected in the Azores that on a close examination in the laboratory could substantiate Pérès observations. Another cidaroid species known to occur in area Cidaris cidaris is characterised by high morphological variability, including the colour of its spines (primary or secondary) which can vary from the typical white or pinkish to brownish-purplish spines (Fig. 20; see also Mortensen 1928). Historically, the Azores was extensively dredged at depths similar to the observations by Pérès (e.g., Koehler 1898, 1909). As a result, abundant material of Cidaris cidaris became available, but remarkable none of the oceanographic cruises managed to secure a single specimen of H. purpurata. Thus, until animals collected in the area prove to belong to this species, the record of this species in the archipelago should be treated with caution.