Antennella tubitheca, Galea, Horia R., 2013

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 : 31-32

Antennella tubitheca sp. nov.

(Fig. 7T–W; Table 4 )

Material examined. Stn. 8, 31.i.2012, 9– 15 m, M129: small, fertile (female) colony on sponge (holotype: MHNG- INVE-82932).

Description. Stems up to 7 mm high, arising from creeping, branching hydrorhiza. Basal part, of varied length, devoid of hydrothecae, carrying up to 4 nematothecae in a fontal row, ending distally with oblique node. Remainder of stem divided heteromerously, with prominent oblique nodes and faintly indicated transverse nodes, not reaching the posterior side of the stem. Hydrothecate segments with proximal oblique node and distal transverse node; a hydrotheca placed in middle region, and four nematothecae. Hydrotheca tubular, adnate for half its length, walls parallel; free adcauline wall straight, abcauline wall slightly flaring distally; rim circular. Nematothecae: a mesial inferior (with the rim of upper chamber notably lowered adaxially), a pair of laterals (with rounded, central, adaxial lobe), and an axiallar one (with slightly lowered rim adaxially). Ahydrothecate segments, nearly the same length as their hydrothecate counterparts, with proximal transverse node and distal oblique node, carrying two frontal nematothecae. Gonothecae, female in present material, arising from below the bases of hydrothecae through a two-segmented pedicel; barrel-shaped, with a pair of nematothecae basally; aperture distal, circular, rim with thickened perisarc, operculum watch-glass shaped. Cnidome: 1) banana-shaped microbasic mastigophores, abundant in the tentacles, also present in the coenosarc; 2) elongate, parallel-sided microbasic mastigophores, in the nematophores, also scattered in the coenosarc.

Remarks. At first glance, this species recalls A. secundaria (Gmelin, 1791) through the segmentation of the stem, the presence of an axillar nematotheca, and the similar shape of the female gonotheca. Mediterranean specimens of this ubiquitous species, as well as colonies from Martinique (notably sample M118), have been used for comparison with the species under discussion. The most significant difference relies in the tubular, comparatively deeper and narrower hydrotheca in the latter species. Additionally, in all the specimens assigned to A. secundaria from Martinique, the ahydrothecate segments are significantly longer than in A. tubitheca . Moreover, discrete differences are noted among the cnidomes of both species: while the new species possesses elongate, parallel-sided microbasic mastigophores in the nematophores and the coenosarc, the same category of capsules has a typically ovoid shape in A. secundaria .

Etymology. From the Latin tubus/tuba, meaning tube, an allusion to the tubular shape of the hydrotheca. Geographical distribution. Only known from Martinique.