Halecium banyulense Motz-Kossowska, 1911

Schuchert, Peter, 2005, Taxonomic revision and systematic notes on some Halecium species (Cnidaria, Hydrozoa), Journal of Natural History 39 (8), pp. 607-639 : 632-634

Halecium banyulense Motz-Kossowska, 1911

( Figure 14 )

Halecium muricatum var. banyulense Motz-Kossowska 1911, p 338 , Figures 10 , 11 . Halecium banyulense: Stechow 1921, p 253 .

Material examined

MHNG INVE 34237 , Mediterranean , Italy, Island of Capri, coll. 22 January 1892, two colonies, one with gonothecae, one overgrown by Lafoea dumosa .

Description

Colonies erect, up to 8 cm high and 6 cm broad, much branched, branches strictly in one plane, branching pattern quite regular, stem and branches polysiphonic, thinning out to monosiphonic terminal regions. Monosipohonic parts segmented through weak nodes, these alternately oblique. Segments elongate, about 1 mm long, with a subterminal apophysis for the next segment and a hydrophore overtopping node of segment, at junction of apophysis and hydrophore a tongue-like process projecting into lumen of internode. Hydrotheca shallow, basal diameter 0.15–0.17 mm, depth 20–40 mm, walls everted, sometimes rim rolled-in, desmocytes present, opening plane of hydrotheca tilted, secondary hydrothecae frequent, first one with hydrophore (length up to twice the diameter), tertiary or higher hydrothecae with short hydrophore ( Figure 13C ). Hydranth with about 22 tentacles. Gonothecae on stem and branches, only female ones could be identified, diameter 1.1 mm, shape resembling a Pecten shell (scallop) through nine or 10 radiating depressions and elevations, these elevations and depressions rounded and without crease-lines, rim of gonotheca slightly undulated.

Further data

Motz-Kossowska (1911) describes the colonies as hermaphroditic, with male and female gonothecae occurring on the same stem. Female gonothecae contain four to six eggs. Male gonothecae are smaller, either smooth or also with ribs.

Distribution

Mediterranean. Type locality: Banyuls-sur-Mer , France .

Remarks

The characteristic female gonotheca ( Figure 13D ) leaves no doubt that the present material belongs to this rare species. The material differed from Motz-Kossowska’s description (1911) only in the more everted hydrothecae ( Figure 13C ).

Motz-Kossowska (1911) described this species as a variant of H. muricatum var. banyulense . Halecium muricatum ( Ellis and Solander, 1786) has gonothecae bearing numerous spines. The gonothecae are not dimorphic as in Motz-Kossowska’s variant. The microscopic structure of the trophosome H. muricatum is also different (cf. Cornelius 1995; Schuchert 2001): the hydrophores are much longer and they have a basal node. Halecium muricatum is a northern boreal to arctic species. The southern limit in Europe is the British Isles. The morphological and geographical differences of H. muricatum and Motz-Kossowska’s variant are evidence enough to regard both as distinct species. The combination Halecium banyulense was used in the species list of Boero and Bouillon (1993).

The female gonothecae of Halecium banyulense and of the arctic Halecium birulai Spassky 1929 resemble each other (see Schuchert 2001 for re-description of H. birulai ). The female gonotheca of the latter species, however, has radiating keels that form more or less sharp crease-lines. Additionally, the hydrothecae are much deeper. It is a purely arctic species and therefore it is very likely distinct from H. banyulense .

Halecium banyulense seems to be a particularly rare species. This report is apparently the second record only, but I suspect that infertile material has occasionally been identified as H. liouυillei Billard, 1934. The latter species was originally described as monosiphonic, but some authors also included polysiphonic colonies in that species (see Medel and Vervoort 2000 for references).

Figures

Figure 10. Halecium labrosum Alder, 1859. (A–D) MHNG INVE 33563, Iceland; (E–G) MHNG 33583, The Faroes. (A) Colony silhouette (scale bar: 1 cm); (B) segments of distal branch, note short internodes (scale bar: 0.2 mm); (C) gonotheca (scale bar: 0.5 mm); (D) distal opening of gonotheca (scale bar: 0.2 mm); (E) colony silhouette (scale bar: 1 cm); (F) segments of distal branches, note variability of internode length; (G) gonotheca (scale bar: 0.5 mm).

Figure 11. Halecium mediterraneum Weismann, 1883; after preserved Mediterranean material. (A) Silhouettes of three fertile colonies showing variability of growth (scale bar: 1 cm); (B) branching pattern of stem (scale bar: 0.2 mm); (C) distal part with geniculate segments (same scale bar as B); (D) primary and secondary hydrotheca (scale bar: 0.1 mm); (E–G) female gonothecae (same scale bar as B), (E) in frontal view and with broad opening, (F) in side view, (G) most commonly found opening size; (H–K) male gonothecae (same scale bar as B), (H) with soft tissue, (I) empty, (K) in side view; (L) empty female gonotheca cut apart to demonstrate secondary capsule within outer capsule (scale bar: 0.1 mm); (M) range of variation of distal openings of female gonothecae (same scale bar as L).

Figure 13. Halecium textum Kramp, 1911; after MHNG INVE 33592, Iceland. (A, B) Hydrothecae and internodes, note strong corrugation (scale bar: 0.1 mm); (C) part of colony with three female gonothecae, eggs stippled (scale bar: 0.5 mm).

Figure 14. Halecium banyulense Motz-Kossowska, 1911, after MHNG INVE 34237. (A) Colony silhouette (scale bar: 1 cm); (B) internode from monosiphonic part (scale bar: 0.2 mm); (C) hydrothecae with regenerated hydrothecae of second and higher degree (scale bar: 0.1 mm); (D) female gonotheca, drawn opaque to visualize radiating depressions (same scale bar as B).