Hydrallmania falcata ( Linnaeus, 1758 )

Calder, Dale R., 2012, On a collection of hydroids (Cnidaria, Hydrozoa, Hydroidolina) from the west coast of Sweden, with a checklist of species from the region 3171, Zootaxa 3171 (1), pp. 1-77 : 36

Hydrallmania falcata ( Linnaeus, 1758)

Fig. 35

Sertularia falcata Linnaeus, 1758: 810 .

Hydrallmania falcata .— Winther, 1880a: 251.— Jäderholm, 1909: 104, pl. 11, fig. 17.— Rees & Rowe, 1969: 20.— Jägerskiöld, 1971: 63.

Hydrallmannia falcata .— Segerstedt, 1889: 19, 27 [incorrect subsequent spelling of Hydrallmania Hincks, 1868 ].

Type locality. England: north Kent, coastal waters ( Cornelius 1979: 273) .

Museum material. Kosterhavet, 58°52.536’N, 11°06.229’E, 6–30 m, 07.ix.2010, SCUBA , one old and quite heavily fouled colony with some new growth, 8 cm high, without gonothecae, coll. B.E. Picton, ROMIZ B3900 .

Remarks. Hydrallmania falcata ( Linnaeus, 1758) is common in the boreal zone on both European and American coasts of the North Atlantic Ocean, and it is frequent in waters of southern Scandinavia ( Kramp 1935b; Jägerskiöld 1971; Christiansen 1972). Its abundance is reflected by the large number of references (>180) with information about the species in the synonymy list of Medel & Vervoort (1998). At one time this hydroid constituted part of the “white weed” fishery in Europe, together with Sertularia argentea Linnaeus, 1758 and S. cupressina Linnaeus, 1758 (e.g., Hancock et al. 1956; Berghahn & Offermann 1999; Wagler et al. 2009). Dryed hydroid colonies were dyed and used for decorative purposes, but the market collapsed due to lack of demand.

Reviews of the biology of H. falcata are given in Cornelius (1979, 1995b). Colony ontogeny of the species, with eventual development of spirally arranged branches having hydrothecae in a single densely-packed series on the upper surface, was described by Kosevich (2006).

An overview of species assigned to Hydrallmania Hincks, 1868 was given by Vervoort (1993), who reported H. falcata from deep waters (1665– 1590 m) off New Caledonia in the western Pacific.

Reported distribution. West coast of Sweden.—Koster area to Öresund ( Winther 1880a; Jägerskiöld 1971).

Elsewhere.—North Atlantic from Svalbard and the Kara Sea ( Kramp 1938; Ramil & Vervoort 1992) to Morocco ( Medel & Vervoort 1998) in the east, and from the Strait of Belle Isle to Long Island Sound ( Calder 2004) in the west.