Halopteris catharina

Halopteris catharina (Johnston, 1833)

(Fig. 3F)

Halopteris catharina: Ramil & Vervoort, 1992: 145–148, fig. 37e–g; Cornelius, 1995b: 126–128, fig. 29; Schuchert, 1997: 107–110, fig. 38; Ansín Agís et al., 2001: 159–163, fig. 68.

Material examined. MAURIT-0911, stn MUDR 01, 16º08´24”N, 16º57´12”W, 488 m, 5-XII-2009: 25 colonies, six colonies growing on bryozoans, one on sponge, three on Aglaophenia lophocarpa, three on Plumularia filicula, one on Halecium sibogae marocanum and one on Nemertesia sp.; without gonothecae.

MAURIT-0911, stn MUDR02, 16º08´50”N, 16º57´01”W, 462 m, 5-XII-2009: seven colonies, no gonothecae.

MAURIT-1011, stn MUDR20, 16º08´11”N, 16º56´08”W, 405 m, 7-XII-2010: two colonies, one of them attached to Aglaophenia lophocarpa, without gonothecae.

MSM 16/3, stn GeoB 14796–1, ROV, 20°14.840’– 20°14.575’N, 17°40.193’– 17°40.071’W, 487–642m, 3-XI- 2010: five colonies 7–17 mm high, one on a sponge, two on Lophelia pertusa, two on Halecium beanii; without gonothecae.

MSM 16 /3, stn GeoB 14801–1, BG, 20°14.762’N, 17°40.173’W, 568 m, 3-XI-2010: two colonies 7 mm high, one on Aglaophenia lophocarpa, no gonothecae.

MSM 16 /3, stn GeoB 14802–1, BG, 20°14.791’N, 17°40.188’W, 595 m, 3-XI-2010: one colony on Lophelia pertusa, no gonothecae.

MSM 16/3, stn GeoB 14886–1, ROV, 18°39.013’– 18°38.476’N, 16°43.580’– 16°43.757’W, 484–640 m, 12-XI- 2010: two colonies 12 mm high, one on Acesta excavata, one on Madrepora oculata, no gonothecae.

Biology. Halopteris catharina has been collected frequently from other hydroids and algae, sponges, corals, worm tubes and ascidians (Ramil & Vervoort 1992; Ansín Agís et al. 2001; Gravili et al. 2013). The gonothecae have been found in February and from April to September (Ansín Agís et al. 2001).

In our material, some colonies were found growing on sponges, other hydroid species, the scleractinians L. pertusa and M. oculata and the bivalve A. excavata.

Distribution. This species has a wide distribution on both sides of the Atlantic Ocean, from the Arctic to the southern-boreal regions, including the Mediterranean Sea (Ramil & Vervoort 1992). For a detailed distribution, see Ansín Agís et al. (2001). In West Africa, H. catharina was collected from Morocco (Ramil & Vervoort 1992), Mauritania (Gil & Ramil 2017a) and Cape Verde Archipelago (Ansín Agís et al. 2001; Vervoort 2006). Its bathymetric range stretches from 1 to 627 m (Ansín Agís et al. 2001; Gil & Ramil 2017a).

The material studied by us was collected from depths of 405 to 642 m.

Remarks. The plumose aspect of the colony with opposed hydrocladia and presence of a supplementary pair of lateral nematothecae helped in accurate identification of this species.