Filellum serpens ( Hassall, 1848 )

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 : 27-28

Filellum serpens ( Hassall, 1848)

Fig. 26

Campanularia serpens Hassall, 1848: 2223 [the specific name serpens Hassall, 1848 conserved and placed on Official List of Specific Names in Zoology, Opinion 1485 (ICZN 1988)].

Filellum serpens .— Segerstedt, 1889: 15, 25.— Lönnberg, 1898: 53.— Jäderholm, 1909: 76, pl. 7, fig. 11.— Kramp, 1935b: 125.— Jägerskiöld, 1971: 62.— Cornelius, 1975b: 379; 1995a: 255, figs. 58A–C.

Type locality. Ireland: Dublin ( Cornelius 1975b: 379) .

Museum material. Kosterhavet, 58°53.039’N, 11°05.602’E, 160 m, 09.ix.2010, biological dredge, R / V Nereus , three colonies, two on Tubularia indivisa stems and one on Abietiniaria abietina , without gonophores, ROMIZ B3905.

Remarks. The genus Filellum Hincks, 1868 and species assigned to it, including F. serpens ( Hassall, 1848) , were reviewed and revised by Peña Cantero et al. (1998) and Marques et al. (2011). Threats to nomenclatural stability of both generic and specific names of F. serpens by lesser known senior synonyms were removed under a ruling (Opinion 1485) by the ICZN (1988).

Ten species were recognized as valid in Filellum worldwide by Marques et al. (2011). Trophosomes in these hydroids are stolonal and simple, comprising sessile and tubular hydrothecae, and identification of species can be difficult or impossible in the absence of gonophores. Gonothecae are aggregated to form a coppinia, the form of which can be diagnostic.

Filellum serpens , type species of the genus by monotypy, is common in southwestern Scandinavia ( Kramp 1935b; Jägerskiöld 1971; Christiansen 1972). It is a boreal, eurybathic species, often found growing on other hydroids and especially on sertulariids ( Cornelius 1995a; Peña Cantero et al. 1998; Marques et al. 2011). Christiansen (1972: 297) also observed it on “...algae, stones, shells, dead Lophelia , calcareous polychaete tubes and tests of the foraminifer Rhabdammina .”

Reported distribution. West coast of Sweden.—From near the border with Norway ( Jägerskiöld 1971) to the Öresund ( Lönnberg 1898; Kramp 1935b).

Elsewhere.—North Atlantic from Spitzbergen and northern seas of the Russian Federation ( Calder 1970) to the Mediterranean Sea ( Peña Cantero et al. 1998) in the east, and from northern Foxe Basin in the Canadian Arctic to Buzzard’s Bay, Massachusetts ( Calder 2004) in the west. Although reports suggest that the species is virtually cosmopolitan, many records are suspect in the absence of coppinia ( Marques et al. 2011). It is likely restricted largely to boreal regions.