Aglaophenia parvula Bale, 1882

Galea, Horia R., 2010, Notes on a small collection of thecate hydroids (Cnidaria: Hydrozoa) from Tristan da Cunha, south Atlantic, Zootaxa 2336, pp. 1-18 : 10-11

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).

Figures

FIGURE 3. A and B: Filellum sp. (material from station Stn. I 10) – portion of colony (A); hydrotheca (B). C: Halecium sp. – four erect stems. D: Halecium cf. beanii (Johnston, 1838) – fragment of monosiphonic part of stem with origin of a side branch. E and F: Halecium cf. delicatulum (Coughtrey, 1876), morphotype 1 – portion of stem (E); hydrotheca (F). G to P: Halecium? delicatulum (Coughtrey, 1876), morphotype 2 (part) – whole colony on piece of alga (G); cross section through the stolon (H); basal part of stem (I); portion of colony (J); various branching patterns (K – M); fragment of stem showing internodes (N); various shapes of primary hydrophores (O); gonotheca arising from primary hydrophore (P). Scale bars: 50 µm (H); 100 µm (F); 200 µm (B, F, O); 300 µm (A, E, I, P); 400 µm (D, K, L, M); 500 µm (N); 2 mm (J); 1 cm (G).

FIGURE 4. A to E: Halecium? delicatulum (Coughtrey, 1876), morphotype 2 (continued) – gonotheca replacing a hydrotheca (A) or arising from stolon (B); mature female gonotheca with eggs (C); various shapes of female gonotheca (D); cross section through gonotheca (E). F and G: Amphisbetia minima (Thompson, 1879) – basal portion of stem (F); gonotheca (G). H to M: Sertularella sp. – basal part of stem (H); fragment of stem showing its straight shape (I) and mode of branching (J); two internodes (K); shape of hydrotheca (L); frontal views of two hydrothecal apertures showing 3 and 5 internal projections of perisarc (M). N and O: Sertularella gayi (Lamouroux, 1821) – fragment of monosiphonic part of stem with basal parts of three side branches (N); various shapes of the hydrotheca (O); P and R: Aglaophenia parvula Bale, 1882 – hydrotheca and detail of its margin (P); female corbula (R). S: Antennella quadriaurita Ritchie, 1909 – detail of stem in lateral (left) and frontal (right) views. Scale bars: 100 µm (M, P); 200 µm (F, S); 300 µm (A, B, E, K, L, O); 400 µm (J); 500 µm (C, D, G); 750 µm (H); 1 mm (I, R); 1.5 mm (N).