Aglaophenia parvula Bale, 1882

(fig. 4 P, R)

Aglaophenia parvula Bale, 1882: 23, pl. 14 fig. 3. – Svoboda & Cornelius, 1991: 25, figs 7–9, 10A–E, 13H, 18, 22–23. – Ansín Agís et al., 2001: 53, fig. 28.

Material examined. Stn. T10, 15.ii.2005: one sterile, unbranched plume, 4.9 cm high (NHM 2009.22). Stn. T17, 06.iii.2005: several stems and fragments, mostly unbranched, up to 4.5 cm high, some bearing corbulae, on algae and sponges. Stn. T18, 06.iii.2005: three sterile, unbranched stems, 6–9 mm high. Stn. T21, 31.x.2007: two sterile, unbranched stems, 1.5 and 4.5 cm high, respectively. Stn. I7, 27.xi.2007: one unbranched, 3 cm high plume, bearing a corbula. Stn. I10, 28.xi.2007: four sterile stems, of which one is branched, up to 3.2 cm high. Stn. N5, 12.xi.2007: several unbranched plumes, up to 4 cm high, some with corbulae, on sponge. Stn. N8, 15.xi.2007: a few stems, up to 3.5 cm high, among which one branched, and one unbranched bearing a corbula. Stn. N10, 17.xi.2007: two sterile, branched stems, 3 and 4 cm high, respectively (NHM 2009.23).

Distribution. Widely spread in the warm and temperate waters around the world (Svoboda & Cornelius 1991). This is the first record of this species for Tristan da Cunha, despite it being the most abundant hydroid in shallow water, particularly on wave-exposed reef crests to 15 m and in exposed littoral pools. For a list of records outside the study area, see Ansín Agís et al. (2001).