Lafoea dumosa ( Fleming, 1820 )

Soto, Joan J. & Peña, Álvaro L., 2019, Benthic hydroids (Cnidaria, Hydrozoa) from the Weddell Sea (Antarctica), Zootaxa 4570 (1), pp. 1-78 : 23

Lafoea dumosa ( Fleming, 1820)

( Fig. 6 i–j)

Material examined. ANT XV/3: 48-50, one colony, up to 55 mm high; 48-194, one colony, up to 50 mm high; 48- 276, one colony, up to 10 mm high, on Sc. nana ; 48-297, one colony, up to 15 mm high, on B. subrufa and ascidian; ANT XVII/3: 111-5, one colony, up to 35 mm high, on O. terranovae ; 111-6, one colony, up to 40 mm high; 111-18, some stems, up to 40 mm high, on O. terranovae and polychaete tube; 111-19, one colony, up to 20 mm high, on Sc. unifurcata ; ANT XXI/2: PS65/121, some stems, up to 40 mm high, on Sc. nana and Sy. curvatus ; PS65/278, one colony, up to 40 mm high, on H. secundum ; PS65/279, one colony, up to 10 mm high, on sponge.

Remarks. Lafoea dumosa has been considered a cosmopolitan species with a wide range of variation in colony shape, pedicel length and hydrothecal morphology [see Schuchert (2001) for a detailed account on the taxonomic history of the species]. Some authors included Lafoea fruticosa (Sars, 1851) and Lafoea gracillima (Alder, 1856) within the synonymy of L. dumosa (e.g. Cornelius 1975; Peña Cantero et al. 2004). However, recent evidence have challenged these previous concepts. Schuchert (2001) found differences in nematocyst size between pedicellate and non-pedicellate colonies of L. dumosa , but some exceptions were noticed by the author. Moura et al. (2008) found two divergent lineages within L. dumosa , suggesting the existence of cryptic species. Finally, Calder (2012) tentatively considered L. fruticosa and L. gracillima as valid species waiting for further molecular work. Given that L. dumosa was originally described from Scotland bearing “nearly sessile cups” ( Fleming 1828: 548; see also Cornelius 1975), the Antarctic representatives of Lafoea , often bearing long and twisted pedicels (figs 6i–j), might belong to a different species. However, in the absence of further molecular evidence, this issue remains open.

Ecology and distribution. In Antarctic waters, reported from 12 ( Stepanjants 1979, as Lafoea fruticosa ) to 1157 m depth ( Peña Cantero 2014a); present material was collected between 65– 417 m. Worldwide distributed, known from both East and West Antarctica (Peña Cantero et al. 2004), as well as the Scotia Arc ( Soto Àngel & Peña Cantero 2015).

Figures

FIGURE 6. a–b Acryptolaria frigida: a stem; b hydrotheca; c–f Filellum antarcticum: c hydrotheca; d coppinia; e section of a coppinia showing gonothecae and eggs; f detail of gonothecal aperture. g Filellum cf. magnificum: hydrotheca. h Filellum cf. bouvetensis: hydrotheca. i–j Lafoea dumosa: i stem; j detail of the stem showing hydrothecal arrangement. k Lafoea gaussica: hydrotheca. l-m Abietinella operculata: l stems; m detail of the stem showing hydrothecal arrangement. n Hebella cf. plana: hydrotheca.