Anthohebella communis ( Calder, 1991 )

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 : 13-14

Anthohebella communis ( Calder, 1991)

( Figs 3 J, Q, R; 4D)

Hebellopsis communis Calder, 1991: 42 , fig. 26.―? Castellanos Iglesias et al., 2011: 20, fig. 11.― Calder, 2013: 19 , fig. 5C.

Hebella communis ― Boero et al., 1997: 34.

? Hebella scandens ― Vannucci, 1949: 236, pl. 2 figs 22, 23; 1951: 82 [not Hebella scandens (Bale, 1888) ].

Material examined. Stn. 6, 14.ii.2012, 10– 17 m, M195: colony composed of numerous hydrothecae and four male gonothecae, epizoic on Thyroscyphus marginatus ( Allman, 1877) (MHNG-INVE-82936).

Remarks. The present material, with hydrothecae 430–500 µm long and 240–265 µm wide, the margin slightly flaring, 250–280 µm wide, and a basal diaphragm, belongs with little doubt to Calder's (1991) species. The cnidome (not previously reported) comprises at least three types of nematocysts: 1) microbasic mastigophores, ca. 6.7×2.1 µm, abundant in the tentacles and the coenosarc; 2) microbasic heteronemes, ca. 5.3×2.6 µm, with rare occurrence in the coenosarc; 3) large, fusiform capsules, ca. 20.2×5.9 µm, exclusively found in the stolon. Small, seed-shaped microbasic heteronemes as those found in the six species of hebellids discussed below, could not be found, most probably owing their rare occurrence in the coenosarc.

The material is fertile and bears four gonothecae. They are conical, 1770–1890 µm long, with slightly undulated, thin perisarc walls, widest distally (465–510 µm), tapering gradually basally into indistinct pedicel, and apically truncate. The gonophore, male in the present material, is a medusoid with four somewhat dark-colored radial canals, well visible by contrasting with the homogenous, milky white mass of sperm cells encircling the manubrium, and completely filling the subumbrellar cavity. No other morphological details could be seen in this fixed material. Given the structure of its gonophore, the allocation of this species to Anthohebella Boero et al., 1997 is required.

The validity of Hebellopsis communis has been questioned by Boero et al. (1997), partly due to the absence of knowledge of its gonothecae and gonophore, and partly to the morphological plasticity in the hebellids in relation to their hosts, suggesting that, if not doubtful, it could well represent a morphotype of Hebella scandens (Bale, 1888) . However, the present discovery of its gonosome shows that A. communis is clearly separable from the medusa-producing H. scandens .

Migotto (1996), after examining the slide material identified as H. scandens by Vannucci (1949, 1951), raised the conclusion that her specimens belong indeed to the present species. His conclusion is adopted here as provisional, pending essential data on its cnidome.

Geographical distribution.? Brazil ( Vannucci 1949, 1951), Bermuda ( Calder 1991),? Cuba ( Castellanos Iglesias5 et al. 2011), Florida ( Calder 2013), and Martinique (present study).

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).