Halecium annuliforme, Galea, Horia R. & Schories, Dirk, 2012

Galea, Horia R. & Schories, Dirk, 2012, Some hydrozoans (Cnidaria) from Central Chile and the Strait of Magellan, Zootaxa 3296, pp. 19-67 : 30-33

Halecium annuliforme sp. nov.

(fig. 2F–M, table 1)

Halecium sp. Galea, 2007: 59, fig. 13E, F.

Halecium annulatum — Jäderholm, 1920: 2, pl. 1 figs 2, 3. (not H. annulatum Torrey, 1902: 49 , pl. 3 figs 30, 31). Halecium delicatulum — Blanco, 1968: 203, pl. 1 figs 14–18, pl. 2 figs 1–3. (not H. delicatulum Coughtrey, 1876 ).

Material examined. Stn. FSI — 04.i.2011, S10 (40 m): numerous minute sterile stems arising from hydrorhiza creeping on Parascyphus repens . Stn. PAR — 07.i.2011, S08 (15 m): a single, sterile stem, epizoic on Halecium pallens . Holotype — Swedish Museum of Natural History, no. 8214 (old no. 599, general catalogue), Lennox Island, 15–20 fathoms, on seaweed.

PLATE 2. A–E: Staurocladia vallentini ( Browne, 1902) —exumbrellar (A–C, E) and subumbrellar (D) views of the medusa; cross section through a medusa stained with Grenacher's alcoholic borax-carmine (insert A). F–H: Samuraia tabularasa Mangin, 1991 —group of polyps and their movements during foraging.

Remarks. This hydroid has been described previously, as Halecium sp., by Galea (2007). As with his specimens, material examined here is unfortunately sterile. Colonies from both studies bear a striking resemblance to hydroids from Lennox Island assigned by Jäderholm (1920) to Halecium annulatum Torrey, 1902 . His material, in collections at the Swedish Museum of Natural History (SMNH #8214 7), was re-examined to determine whether it is conspecific. Jäderholm’s hydroid comprises a small colony growing on seaweed, with a dozen stems (some unbranched, some sparingly-branched), up to 3 mm high, and four gonothecae. The stems are morphologically indistinguishable from those in our material (compare fig. 2F and G), except for somewhat thicker perisarc. A pseudodiaphragm is present in some hydrothecae but absent in others (fig. 2I). Gonothecae are small, stolonal, borne on rather long pedicels, lenticular in shape with a circular aperture, and with slightly thickened perisarc. Some contain a few spherical eggs, ca. 50 µm in diameter (fig. 2L). The stout habit of the colony, as well as hypertrophy of its perisarc, may be due to continual movement of its algal substrate.

Jäderholm's hydroid appears clearly different from Torrey's (1902) species in the following respects: 1) branching is spare and very irregular, while specimens of the latter had "regularly alternating branches"; 2) the internodes of the former are slender, very irregular and long, while H. annulatum forms rather short internodes giving rise to "hydrothecae alternately on either stem or branch"; 3) the hydrothecae of the former are borne on primary hydrophores varied in length, and are definitely sessile in Torrey’s species.

The hydroid from Lennox Island, misidentified earlier as Halecium annulatum , is designated as holotype of Halecium annuliforme sp. nov. Our specimens, and those of Galea (2007), are referred to this new species. Moreover, the description and figures of a hydroid assigned by Blanco (1968) to H. delicatulum Coughtrey, 1876 leave little doubt that it is conspecific.

Stout species of Halecium with wrinkled stems and branches resembling H. annuliforme include: H. corrugatissimum Trebilcock, 1928 , H. corrugatum Nutting, 1899 , and H. textum Kramp, 1911 . However, gonothecae of these species are different: those of H. corugatissimum are transversely ridged and provided with a

7. This sample also contains two other haleciids, each represented by a several millimeter high fragment. One of these is sterile and could be provisionally assigned to H. jaederholmi Vervoort, 1972 (fig. 2N), the other bears male gonothecae and is unidentifiable (fig. 2 O). If these additional species were originally present in sample #8214 and are not the result of a subsequent contamination, the finding of H. jaederholmi at Lennox Island represents the first record of this species from Chile. For a full list of distribution records, see Peña Cantero (2008).

pair of protruding hydranths ( Schuchert 2005); those of H. corrugatum are urn-shaped with a large apical aperture (see Fraser 1914); and those of H. textum are ovoid, less compressed laterally, and distally truncate at the aperture ( Schuchert 2005).

Etymology. The specific epithet refers to the annulated shape of the stems and branches.

Distribution in Chile. Lennox Island ( Jäderholm 1920, as Halecium annulatum Torrey, 1902 ), Camello Island (Galea 2007, as Halecium sp.), Strait of Magellan (present study).

World records. Isla de los Estados, Argentina ( Blanco 1968).