Lafoea dumosa

Lafoea dumosa (Fleming, 1820)

Fig. 27

Sertularia dumosa Fleming, 1820: 84.

Lafoea dumosa.— Segerstedt, 1889: 15, 26.— Jäderholm, 1909: 71, pl. 7, fig. 5.— Gislén, 1930: 332.— Rees & Rowe, 1969: 14.— Jägerskiöld, 1971: 63.— Cornelius, 1975b: 386.

Type locality. UK: Scotland, Arbroath (Cornelius 1975b: 386).

Museum material. Kosterhavet, 58°52.424’N, 11°06.178’E, 85 m, 06.ix.2010, Warén dredge, R / V Nereus, three colony fragments, up to 2 cm high, without gonothecae, ROMIZ B3888.

Remarks. The concept of Lafoea dumosa (Fleming, 1820) adopted here is restricted in scope to the morphotype defined in traditional accounts of the species (e.g., Jäderholm 1909; Broch 1918; Stechow 1925; Totton 1930; Kramp 1935b; Fraser 1944; Vervoort 1946; Calder 1970). As such it does not include L. fruticosa (M. Sars, 1850) and L. gracillima (Alder, 1856) as synonyms. Additional discussion of the matter is given below in remarks under L. gracillima. While synonymy of the three nominal species is possible or even likely, it seems best to keep them separate pending further evidence. Recent molecular and life cycle studies have shown taxonomic lumping in the latter half of the twentieth century to have often been excessive, and a conservative approach seems warranted in addressing this possible species complex. Indeed, preliminary molecular work by Moura et al. (2008) suggests existence of cryptic species in L. dumosa.

Fleming (1820) used the name Sertularia dumosa in conjunction with a hydroid that he briefly compared and contrasted with Sertularia verticillata Linnaeus, 1758 (now Rhizocaulus verticillatus). According to Fleming, it differed from the species described and illustrated by Ellis (1755: 23, No. 20, pl. 13, figs.a, A) as the “horse-tail coralline” (R. verticillatus) in having “...irregularly disposed, and nearly sessile cups.” Cornelius (1995a: 261) considered the name as established in Fleming’s early work a nomen nudum, implicitly regarding the four-line account insufficient as a description or definition under the International Code of Zoological Nomenclature (ICZN 1999). While the description was intentionally preliminary, and a somewhat fuller one was provided later (Fleming 1828, as Campanularia dumosa), some currently accepted names of hydroids are based on less information (e.g., see discussion of Hydractinia sodalis Stimpson, 1858 in Calder 2010: 34). The account by Fleming (1820) satisfies the requirements of Art. 12.1 of the code, in my opinion, and the specific name dumosa is taken here as available from that date. Threats to nomenclatural stability are also thereby avoided. Had the name L. dumosa not been made available until 1828, that well-known binomen would be a junior subjective synonym of the virtually unused and lesser known L. cornuta Lamouroux, 1821.

Lafoea dumosa appears to be the most common and widespread species of the genus in southwestern Scandinavia (Kramp 1935b; Rees & Rowe 1969; Jägerskiöld 1971; Christiansen 1972).

Reported distribution. West coast of Sweden.—From Säcken Reef to southern Kattegat (Rees & Rowe 1969; Jägerskiöld 1971).

Elsewhere.— North Atlantic from northern Greenland to the Cape Verde Islands (Schuchert 2001a; Vervoort 2006) in the east, and from Ungava Bay to the Caribbean Sea (Vervoort 1968; Calder 1970) in the west. Reportedly circumglobal.

FIGURE 28. Lafoea gracillima: part of branch with hydrothecae, ROMIZ B3912. Scale equals 0.5 mm.