Halecium beanii

Halecium beanii (Johnston, 1838)

(fig. 12A–D, table 16)

Thoa beanii Johnston, 1838: 120, pl. 7 figs 1–2.

Halecium beani (i): Hincks, 1868: 224, pl. 34 fig 2; Hartlaub, 1905: 604, figs A 3 –B 3; Fraser, 1912: 366, fig. 27; Stechow, 1919: 33; 1923: 5; Fraser, 1944: 186, pl. 33 fig. 160; Vervoort, 1959: 224, fig. 6; Ralph, 1958: 332, fig. 10A–B, E– K; Vervoort, 1966: 103, fig. 3; Rees & Rowe, 1969: 12; Naumov, 1969: 483, fig. 336; Vervoort, 1972a: 30, figs 6–7; Leloup, 1974: 10, fig. 7; Millard, 1975: 144, fig. 47A–E; Blanco, 1976: 30, pl. 1 figs 4–7; Stepanjants, 1979: 108, pl. 16 fig. 6; Rees & Vervoort, 1987: 23, fig. 4A–B; Ramil Blanco & Iglesias Dias, 1988: 71, fig. 1; Gili et al. 1989: 77, fig. 7A; El Beshbeeshy, 1991: 29, fig. 3; Cornelius, 1995a: 276, fig. 62; Hirohito, 1995 (English text): 17, fig. 3D–F, pl. 1, fig. A; Ramil et al., 1998b: 7; Medel & Vervoort, 2000: 8, fig. 1; Schuchert, 2000: 413; 2001a: 73, fig. 59; Vervoort & Watson 2003: 86, fig. 15D–H; Bouillon et al., 2004: 139, fig. 73F–J; Schuchert, 2005: 615, figs 5–6; Vervoort, 2006: 252.

Halecium beanei: Stechow, 1919: 33.

Material examined. Stn. MEL 01 —08.iii.2005, 10– 15 m, S19: six stems, 3–4 cm high, some fertile, with male gonophores, 3 slides (MHNG INVE 53173).

Type locality. Near Scarborough, Yorkshire, England.

Description. Colonies 3–4 cm high, arising from encrusting hydrorhiza; stem slightly polysiphonic basally, grading to monosiphonic distally; stem markedly geniculate with short internodes delimited by transverse to slightly oblique nodes; perisarc reatively thick and slightly brown in color. Internodes with distal hydrotheca, alternately placed left and right, rim not surpassing distal node. Branches irregularly alternate, borne on short stem apophyses situated below stem hydrothecae; structure of branches similar to that of stem; perisarc of branches becoming thinner towards tips. Cauline hydrothecae with thin walls, contrasting with thick perisarc of rest of caulus. Primary hydrothecae borne on short hydrophores, held oblique to main axis of internode. Hydrotheca shallow, walls slightly diverging distally, aperture rounded, rim even, opening plane of hydrotheca inclined; desmocytes visible as numerous refringent nodules. No secondary hydrophores have been observed in present material. Male gonophores present in some colonies: club-shaped, walls nearly parallel, distal part rounded, base tapering abruptly; borne on short pedicel inserted below hydrotheca.

Remarks. Both H. beanii and H. halecinum (Linnaeus, 1758) were reported from the Pacific (see Schuchert 2005). Vervoort & Watson (2003) pointed out that both species can be securely separated only in the presence of female gonothecae. Cornelius (1995a) showed that sterile material is still distinguishable based on the general shape of old colonies, which are regularly pinnate in H. halecinum and irregularly branched in H. beanii. However, Schuchert (2005) found some exceptions for H. halecinum, but recognized that the pinnate colony form is certainly diagnostic of this species.

The present specimens have irregularly branched colonies and fit well with the available descriptions of H. beanii (Vervoort 1972a, Schuchert 2005). Moreover, only H. beanii has been previously reported from Chile (Hartlaub 1905, Leloup 1974).

Hydroid epibionts. Halecium delicatulum Coughtrey, 1876.

World distribution. Cosmopolitan, penetrating well into the Arctic Ocean and the coasts of Patagonia, but not into the Antarctic (Medel & Vervoort, 2000).

Records from Chile. Previous records of this species are from Golfo Corcovado (Jäderholm 1905), Canal Beagle (Jäderholm 1910), Golfo de Ancud and Seno Reloncavi (Leloup 1974). The present material was found at only one station, Melinka, Guaitecas Archipelago.