Zanclea migottoi, Galea, Horia R., 2008

Galea, Horia R., 2008, On a collection of shallow-water hydroids (Cnidaria: Hydrozoa) from Guadeloupe and Les Saintes, French Lesser Antilles, Zootaxa 1878, pp. 1-54 : 14-15

Zanclea migottoi sp. nov.

(fig. 3J–L, tables 1–2)

Zanclea costata — Migotto, 1996: 20, fig. 5A–C (not Zanclea costata Gegenbaur, 1857: 229 , pl. 8 figs 4–6). Zanclea cf. alba — Vervoort, 2006: 200, figs 1A–B, 2.1–2.3 [not Zanclea alba sensu Calder (1988b) = Acrochordium album Meyen, 1834: 165 , pl. 28 fig. 8].

Type material. Stn. 3: 26.01.2008 —several small colonies, composed of a few hydranths, some with medusa buds, on algae ( MHNG INVE 61000).

Type locality. Petite Anse, Basse-Terre, Guadeloupe.

Description. Colonies stolonal, monomorphic, with hydranths arising from creeping hydrorhiza. Pedicels 735–1790 µm long, 45–65 µm in diameter basally, gradually widening distally to 85–180 µm. Perisarc strongly corrugated basally (not forming distinct annuli), smooth distally. Hydranths cylindrical, 635–980 µm long, 170–230 µm wide; slightly tapering basally; hypostome rounded, short. About 30–40 tentacles, of which 5–6 around mouth, the remaining ones scattered more or less regularly over 2/3 of body; all tentacles capitate, 100–160 µm long, 45–50 µm wide at base, diameter of capitulum 50–60 µm. Gonophores, medusa buds, borne in small clusters on short stalks among basal tentacles. Newly-liberated medusa not seen. Nematocysts of polyp (undischarged capsules, for dimensions see table 1): two size classes of stenoteles in tentacle tips; macrobasic euryteles, with parallel sides and rounded ends, in groups of 2–7 capsules at bases of tentacles. Nematocysts of medusa buds: stenoteles and macrobasic euryteles with bean-shaped capsules.

TABLE 1. Comparative measurements of the nematocysts from polyps of Zanclea migottoi sp. nov., from various sources, in µm. (1)Nematocysts from preserved material. (2)Nematocysts from living material.

Remarks. The various nominal species of Zanclea Gegenbaur, 1857 can be reliably identified only if the entire life cycle is known. However, recent studies ( Gravili et al. 1996, Boero et al. 2000, Puce et al. 2002) described in detail the morphological features of both the polyp and medusa stages of numerous members of the genus, and provided essential data on their nematocyst complement. As stated by Gravili et al. (1996), study of the cnidome is an essential tool for species identification in Zanclea hydroids.

The nematocyst complement of the present hydroid material was compared with the available data from the literature, and proved to be identical with the Brazilian specimens assigned to Z. costata Gegenbaur, 1857 by Migotto (1996). Although not stated in the original description given by this author, the macrobasic euryteles of the polyp are located in groups of 2–5 capsules at the tentacle bases and have the same shape as those found in the Guadeloupe hydroids. Their shaft is 10 times or more longer than the capsule itself. Moreover, the macrobasic euryteles of the Brazilian medusa are bean-shaped and thus resemble those of the medusabuds in my material (A. E. Migotto, personal communication).

From the cnidome data, it is obvious that the Brazilian material does not belong to Gegenbaur’s (1857) species. The latter is only known from the Mediterranean and has a different cnidome in both the hydroid and medusa stages, as illustrated by the detailed description given by Cerrano et al. (1997).

Additionally, the hydroid material from the Azores assigned to Zanclea cf. alba ( Meyen, 1834) by Vervoort (2006) comes very close to ours. The macrobasic euryteles, in particular, in Vervoort’s (2006) specimens have the same shape and size as those from the Guadeloupe hydroids, and are similarly located at the bases of tentacles, as illustrated in his fig. 2–2.

However, the material included by Vervoort (2006) in the synonymy of Meyen’s (1834) species is different from that attributable by Calder (1988b) to Z. alba . The latter author neither reported macrobasic euryteles in his original redescription of Z. alba (see Calder 1988b), nor found them during a recent reexamination of three different samples from Bermuda (D. Calder, personal communication).

Therefore, the Brazilian specimens are regarded here as being conspecific with the present material from Guadeloupe and that from the Azores. The macrobasic euryteles did not match any of those described in the known Zanclea species, and all the above-mentioned materials are allocated to the new species Z. migottoi . For a description of its medusa stage, see Migotto (1996). A comparison of various species of Zanclea with a known hydroid stage and monomorphic colonies is presented in table 2.

Etymology. This species is named after Dr. Alvaro E. Migotto, who found and described it for the first time.

Distribution. The Azores ( Vervoort 2006), Caribbean Sea (present study), Brazil ( Migotto 1996).