Halisiphonia galatheae Kramp, 1956

Marques, Antonio Carlos, Cantero, Alvaro Luis Peña & Migotto, Alvaro Esteves, 2006, Revision of Halisiphonia Allman, 1888 (Cnidaria, Hydrozoa, Hebellidae), with comments on its taxonomic position, Journal of Natural History 40 (17 - 18), pp. 1047-1062 : 1052-1055

Halisiphonia galatheae Kramp, 1956

( Figure 2D ; Table II)

Halisiphonia galatheae Kramp 1956, p 17 –18, Figure 3 ; Vervoort 1966, p 121–122, Figures 22, 23; Belyaev 1972, p 48.

Material examined

Holotype: Halisiphonia galatheae Kramp, 1956 ; colony with gonothecae in alcohol ( ZMUC no number).

Type locality

Kermadec Trench (north of New Zealand), 35 ° 169S, 178 ° 409W, 8210–8300 m, 14 February 1952, on rock (bottom grey clay with pumice), ‘‘Galathea’’ Expedition Sta. 649. Description of holotype

Colony stolonal, with many hydrothecae and two gonothecae arising from hydrorhiza. Hydrorhiza 0.12–0.16 mm wide, forming a sparse network of branching tubes of thin perisarc. Pedicel straight, cylindrical, elongated, 3.96–11.00 mm long, 0.10–0.16 mm wide, smooth but with two to six complete basal annuli; slightly and progressively widening to base of hydrotheca, merging into it almost imperceptibly. Hydrotheca deep conical, 0.70–1.20 mm high (from diaphragm up to distal renovation), 0.16–0.36 mm wide at diaphragm, 0.28–0.80 mm wide at aperture, with straight and smooth walls, and thin perisarc; margin entire, not flaring, with up to six renovations; aperture perpendicular to long axis of hydrotheca. Diaphragm membraneous, transversal, not conspicuous and sometimes lacking; desmocytes not seen. Hydranths not present.

Gonothecae spatulate, laterally compressed, rounded basally, truncated apically, with a narrow transverse slit as superior aperture, arising singly from hydrorhiza on short, annulated pedicels. Pedicel 0.40–0.50 mm high, 0.10–0.14 mm wide. Gonotheca 1.80– 2.04 mm high, 1.44–1.48 mm wide at aperture, 0.16–0.26 mm wide at base.

Nematocysts of one category, heterotrichous?microbasic mastigophores (not seen discharged), 9.0–10.0X2.0–3.0 Mm, rice grain-shaped, common.

Remarks

Kramp’s (1956) description of H. galatheae is brief, particularly with regard to colony dimensions; the range of variation or average values of important characters are not given. Kramp (1956, p 17–18) did not recognize gonothecae in the holotype and overlooked that the hydrothecal pedicels are annulated at their bases. He reported pedicels much longer (25 mm) than those found by us (11 mm), but the other measurements given by him are within the range of variation we obtained, except the width of the pedicel, which is slightly thinner than the ones we measured. Nonetheless, H. galatheae is a well-characterized species due to the straight hydrothecal margin (not everted) and longer pedicels. Rees and Vervoort (1987, p 34) regarded H. galatheae as conspecific with H. megalotheca , due to the existence of intermediate specimens, regarding the pedicel length, and the similarity of their gonothecae. Contrary to their argument, H. galatheae have much longer and more slender pedicels than those studied by them or by previous authors ( Rees and Vervoort 1987, p 33, Table 4). Moreover, the demarcation between pedicel and hydrotheca in H. galatheae is indistinct, whereas in the holotype of H. megalotheca hydrotheca and pedicel are clearly distinct. The illustrations of material identified as H. megalotheca by Vervoort (1972, p 60, Figure 17a) and Rees and Vervoort (1987, p 31, Figure 6a, b) are also distinct from H. galatheae in this aspect. On the contrary, H. galatheae assigned by Vervoort (1966, p 122, Figure 24), later considered as H. megalotheca by Rees and Vervoort (1987), agrees well with the holotype of H. galatheae , having comparable long pedicels and straight margins. The type specimens of H. galatheae and H. megalotheca also differ in the presence of annuli on the pedicel and non-flaring hydrothecal rim of the former.

Distribution

The species is known from north of New Zealand ( Kramp 1956) and Celebes Sea ( Vervoort 1966), at depths varying from 4940 ( Vervoort 1966) to 8300 m ( Kramp 1956).

Figures

Figure 2. (A–C) Halisiphonia megalotheca Allman, 1888: (A) gonotheca (left) and hydrotheca, lateral view; (B) base of hydrotheca; (C) base of hydrotheca showing desmocytes; (D) Halisiphonia galatheae Kramp, 1956: gonotheca, lateral view. Scale bars: 800 Mm (A); 500 Mm (B); 25 Mm (C); 450 Mm (D).

Figure 3. Halisiphonia nana Stechow, 1921. (A) Hydrothecae, lateral view; (B) portion of a colony; (C) terminal part of hydrotheca with renovations; (D) base of hydrotheca, showing diaphragm. Scale bars: 250 Mm (A); 125 Mm (B); 100 Mm (C); 25 Mm (D).