Hebella

Galea, Horia R., 2013, New additions to the shallow-water hydroids (Cnidaria: Hydrozoa) of the French Lesser Antilles: Martinique, Zootaxa 3686 (1), pp. 1-50 : 15

Hebella sp. 1

( Figs 3 M, Z; 4G)

Material examined. Stn. 1, 18.ii.2012, 13 m, M217: several hydrothecae on three cormoids of Aglaophenia rhynchocarpa Allman, 1877 .

Description. Stolon linear, occasionally branched, creeping mostly on the posterior side of the host's stem, giving rise irregularly to rather short (210–550 µm), slightly wrinkled pedicels, carrying large (1160–1645 µm long, 560–610 µm wide), campanulate hydrothecae; walls smooth or nearly so, rounded and slightly asymmetrical basally, with thin, membranous diaphragm; margin circular, strongly everted, 770–940 µm wide at aperture, occasionally renovated once; hydranths with 18–19 tentacles. Gonothecae absent. Nematocysts: 1) egg-shaped microbasic heteronemes, ca. 5.8×3.4 µm, of rare occurrence in the coenosarc; 2) microbasic mastigophores, (7.8– 9.0)×(2.6–2.9) µm, abundant in the tentacles, also present in the coenosarc; 3) ovoid microbasic heteronemes with a lateral "beak" at insertion of the shaft, (7.4–8.0)×(2.9–3.2) µm, sparsely distributed in the coenosarc; 4) large microbasic heteronemes, ca. 22.3×7.2 µm, occurring rather rarely in the stolon.

Remarks. In the absence of knowledge of its gonosome, this hydroid, as well as the three following species, could not be linked to any known taxa. According to Fig. 4 D–J, in which the cnidomes of the seven hebellids discussed here are compared, it appears that at least some of them produce capsules with a very characteristic shape. These, together with the features of their trophosomes alone, could possibly allow a specific identification in some cases, provided that their life cycles are already known and specific names are introduced for those that appear as new. Unfortunately, the review by Boero et al. (1997) paid little attention to the cnidomes, thus preventing any reliable comparisons based on the nematocysts and trophosomes alone.

Geographical distribution. Only known from Martinique.

Figures

FIGURE 3. A, B: Clytia hemisphaerica (Linnaeus, 1767) ― hydro- (A) and gonotheca (B). C, D: Clytia noliformis (McCrady, 1859) ― hydro- (C) and gonotheca (D). E:? Gastroblasta sp. ― hydrotheca. F, G: Orthopyxis sargassicola (Nutting, 1915) ― hydro- (F) and gonotheca (G). H, I: Egmundella humilis Fraser, 1936 ― hydro- and nematothecae from samples M 231 (H) and M 007 (I). J – P: Relative sizes of the hydrothecae of the hebellids discussed in the text. J, Q, R: Anthohebella communis (Calder, 1991) ― hydrothecae (J, Q) and gonotheca with medusoid gonophore (R). K, S, T: Hebella dyssymetra Billard, 1933 ― hydrothecae. L, U – Y: Hebella scandens (Bale, 1888) ― hydrothecae (L, U); gonotheca seen laterally (V) and apically (X), showing the four-flapped operculum; gonophore (Y). M, Z: Hebella sp. 1 ― hydrotheca. N: Hebella sp. 2 ― hydrotheca. O: Hebella sp. 3 ― hydrotheca. P: Hebella sp. 4 ― hydrotheca. Scale bars: 200 µm (H, I, Z), 300 µm (A – E, S, T), 500 µm (Q, R, U – Y), 1 mm (F, G, J – P).

FIGURE 4. A: Hebella sp. 2 ― hydrothecae. B: Hebella sp. 3 ― hydrothecae. C: Hebella sp. 4 ― hydrothecae. D – J: Comparison of the cnidomes of Anthohebella communis (Calder, 1991) (D), Hebella dyssymetra Billard, 1933 (E), Hebella scandens (Bale, 1888) (F), Hebella sp. 1 (G), Hebella sp. 2 (H), Hebella sp. 3 (I), Hebella sp. 4 (J). K – Q: Halecium dichotomum Allman, 1888 ― various stems (K); male (L, M) and female (N, P) gonothecae; aperture of a female gonotheca in frontal view, showing twin hydrotheca (O); cnidome (Q). Scale bars: 10 µm (D – J, Q), 300 µm (K – P), 500 µm (C), 1 mm (A, B).