Zanclea giancarloi Boero, Bouillon and Gravili, 2000

Gravili, Cinzia, Vito, Doris De, Camillo, Cristina Gioia Di, Martell, Luis, Piraino, Stefano & Boero, Ferdinando, 2015, The non-Siphonophoran Hydrozoa (Cnidaria) of Salento, Italy with notes on their life-cycles: an illustrated guide, Zootaxa 3908 (1), pp. 1-187 : 70-72

Zanclea giancarloi Boero, Bouillon and Gravili, 2000

Fig. 48 A–E

See Schuchert (2010) for a complete synonymy.

Material examined. HCUS-S 053p and HCUS-S 053m (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula)—polyp and medusa stages.

Description (based on our own observations; Gravili et al. 1996 as Zanclea sp.; Boero et al. 2000; Schuchert 2010):

Hydroid. Hydrorhiza reticular; colony stolonal; hydrocaulus as hydranth pedicel, covered by slightly corrugated perisarc; hydranths cylindrical, elongated; with 4–8 oral capitate tentacles in one whorl; 50–60 aboral capitate tentacles scattered over the whole hydranth body; medusa buds in clusters among tentacles in the lower third of the hydranth. Colours: perisarc brownish, hypostome whitish, hydranth transparent, gastric wall pinksalmon.

Habitat type. The colonies have been found in depths from nearly the water surface to 30 m ( Gravili et al. 1996; this study).

Substrate. The polyps of this species grow on a variety of substrates, including Bryozoa, where colonies grow under the skeleton of the bryozoan host, algae, sponges, concretions, rocks.

Seasonality. In Salento waters, Z. giancarloi occurs from June to September (Boero et al. 2000), November–July (De Vito 2006; this study), January–June, September ( Gravili et al. 1996; Boero et al. 2000; C. Gravili unpublished observations).

Reproductive period. In Salento waters, fertile colonies occur from August to September ( Gravili et al. 1996; Boero et al. 2000).

Medusa. Adult. Mature medusa short-lived (matures within 5 days), not much different from young one, tentacles and manubrium longer, gonads interradial, females with 2 eggs per quadrant.

Developmental stages. Newly released medusa almost spherical; with 4 perradial, oval nematocyst patches containing stenoteles on exumbrella; manubrium tubular, simple, spanning about half of the subumbrellar cavity; 4 radial canals, well visible, no linear swellings; without visible gonads; 4 marginal bulbs, one opposite pair large, the other very small; each large bulb bearing one long, tapering, contractile tentacle with cnidophores, cnidophores all on one side of tentacles, contractile, each with usually 3–5 macrobasic euryteles, distally with long cilia.

Cnidome. Stenoteles of two sizes in tentacle capitations; apotrichous macrobasic euryteles of two sizes, both with shaft coiled along the long axis of capsule, the larger ones with spines for one fifth of their length when extruded, the smaller ones with spines for one tenth of their length, both present in hydrorhiza and hydranth body (polyp); two size classes of stenoteles; telotrichous macrobasic euryteles in cnidophores; very rare microbasic euryteles may be on exumbrella.

Distribution. Mediterranean Sea to Bay of Biscay (Boero et al. 2000; Bouillon et al. 2004; Gravili et al. 2008a; Schuchert 2010).

Records in Salento. Rare in the following localities: S.ta Caterina, Ionian Apulian coast ( Gravili et al. 1996 as Zanclea sp.; Miglietta et al. 2000); La Strea, Porto Cesareo ( Faucci & Boero 2000); Otranto (De Vito 2006; Gravili 2006; Gravili et al. 2008a; Piraino et al. 2013; this study).

Remarks. The whole life cycle was examined in the present study. As remarked by Gravili et al. (1996), the hydroid of Z. giancarloi is similar to that of Z. costata , but the two species differ in cnidome and host (a bryozoan instead of a bivalve). The two types of macrobasic euryteles in the Z. giancarloi hydroid are a distinctive character, readily differentiating the species.

References. Gravili et al. (1996) as Zanclea sp.; Boero et al. (2000), Faucci & Boero (2000), Miglietta et al. (2000), Bouillon et al. (2004), De Vito (2006), Gravili (2006), Gravili et al. (2008a), Schuchert (2010), Piraino et al. (2013).

Figures

FIGURE 48. Zanclea giancarloi: A, hydranth; B, cnidome of hydroid, comprising undischarged stenoteles of two sizes and undischarged and discharged macrobasic euryteles of two sizes; C, newly released medusae (same scale as E); D, cnidome of medusa comprising undischarged stenoteles of two sizes, undischarged and discharged macrobasic euryteles from cnidophores and undischarged microbasic euryteles (?) from exumbrella (same scale as B); E, adult female medusa (modified after Boero et al. 2000). Scale bars: A, 1.0 mm; B, D, 10 µm; C, E, 0.5 mm.