Hebella scandens (Bale, 1888)

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 scandens (Bale, 1888)

( Figs 3 L, U– Y; 4F)

Material examined. Stn. 3, 19.ii.2012, 10– 15 m, M226: fertile colony on Thyroscyphus marginatus ( Allman, 1877) .

Remarks. For a description of this species and a list of synonyms, see Boero et al. (1997). A medusa bud obtained from a dissected gonotheca showed the presence of a wide manubrium with no apparent gonads, at least two (possibly three) long tentacles and four large marginal bulbs, each bearing a black pigment spot ( Fig. 3 Y). Altuna (1996) reported medusae at liberation with 3–4 marginal tentacles, and ocelli appearing after one day of free living, while the medusae examined by Migotto (1996) had 2 perradial tentacles at liberation, and the ocelli only became apparent in 3-day old medusae.

The cnidome of the polyp (not thoroughly documented previously) comprises four types of capsules: 1) microbasic heteronemes, ca. 5.3×3.4 µm, of rare occurrence in the coenosarc; 2) a fusiform microbasic mastigophore, (5.9–6.4)×(2.1–2.4) µm, abundant in the tentacles and the coenosarc; 3) a rare microbasic heteroneme occurring in the coenosarc, rather poorly distinguishable from the former mastigophores (type 2), except for its globally more swollen capsule, ca. 5.9×2.4 µm; 4) a large microbasic mastigophore, (17.6– 19.1)×(5.3–5.8) µm, quite abundant in the stolon.

The cnidome of the medusa bud comprises apparently only two types of microbasic mastigophores: 1) one with small, fusiform capsules, (6.4–6.9)×(2.1–2.4) µm; 2) larger, ovoid capsules, (9.3–10.1)×(4.8–5.0) µm. Their distribution could not be checked in the present material, though both Altuna Prados (1996) and Migotto (1996) found the former in the tentacles, as well as in the atentaculate marginal bulbs, and the latter scattered on the exumbrella.

Geographical distribution. Circumglobal (Millard 1975), except for polar seas.

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).