Amphisbetia minima (Thompson, 1879)

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 : 9

Amphisbetia minima (Thompson, 1879)

( fig. 4 F, G)

Sertularia minima Thompson, 1879: 104 , pl. 17 fig. 3 .

Amphisbetia minima – Millard, 1975: 250, fig. 82H–K. – Vervoort & Watson, 2003: 107, fig. 20J–L.

Material examined. Stn. T21, 31.x.2007: two colonies 4–5 mm high, with female gonothecae, on algae ( NHM 2009.19).

Distribution. Temperate and sub-Antarctic waters of the southern hemisphere (Vervoort & Watson 2003). This is the first record of this species for Tristan da Cunha.

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).