Bougainvillia nana Hartlaub, 1911

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 : 10-11

Bougainvillia nana Hartlaub, 1911

Fig. 3 A–C

See Denitto et al. (2007a) for a complete synonymy.

Material examined. HCUS-S 0 0 3 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula) - polyp stage.

Description (after Denitto et al. 2007a):

Hydroid. Hydrorhiza simple; colony stolonal; hydrocaulus monosiphonic, unbranched; hydranths clavate, about 1.0 mm long, not covered by pseudohydrotheca, with 10–16 amphicoronate filiform tentacles (maximum length of 1.75 mm); hypostome short and conical. Medusa buds up to 4 per hydranth/hydrocaulus, growing in clusters on a short peduncle either on the upper part of hydrocaulus or at the base of hydranth and showing 4 distinct radial canals a few days after their first appearance. Colours: hydranths orange; hypostome milky; medusa buds orange.

Cnidome. Microbasic euryteles and desmonemes, both on tentacles and hydranth of the polyp stage.

Habitat type and substrate. Organic substrate composed by coralline algae, hydrorhizae of Aglaophenia sp. (Hydrozoa) and Ircinia sp. (Porifera) ( Denitto et al. 2007a).

Seasonality. January–May in Salento waters ( Denitto et al. 2007a).

Reproductive period. February ( Denitto et al. 2007a).

Medusa. Adult. Umbrella globular, up to 2.0 mm high and 1.4 mm wide; mesoglea thick (up to 0.7 mm); subumbrella quadrangular, 0.6 mm–0.7 mm height and 1.0 mm width, exumbrella with exumbrellar spots (not nematocysts) still visible in young yet mature medusae but disappearing in fully developed individuals; manubrium pyriform, about 0.4 mm long, not mounted on a gastric peduncle; oral tentacles branched once (some of them unbranched or branching twice). Gonads interradial, pouch-like, in females 1 or 2 big eggs armed with microbasic euryteles cnidocysts in each gonad. Two long marginal tentacles per marginal bulb, moniliform-like and with swollen and ciliated tip (cilia are visible only under high magnifications); 2 ocelli on each marginal bulb. Colours: subumbrella light greenish in colour when illuminated by a direct light, exumbrella colourless; ocelli dark-red.

Developmental stages. Newly released medusa with globular umbrella, 0.75 mm wide and 0.65 mm high, with numerous regularly distributed spots (not nematocysts) on exumbrella; manubrium cylindrical, not mounted on a gastric peduncle; oral tentacles unbranched; 2 long moniliform-like tentacles and 2 ocelli per marginal bulb. Colour: ocelli dark-red.

Distribution. Mediterranean endemic ( Denitto et al. 2007a).

Records in Salento. Rare in the following localities: Peninsula ‘La Strea’ (Marine Protected Area of Porto Cesareo), S.ta Caterina and in the submarine cave ‘Grotta delle Corvine’ (Baia di Uluzzo, Nardò) (Ionian Sea, Southeast Italy) ( Denitto et al. 2007a).

Remarks. The whole life cycle was examined in the present study. Denitto et al. (2007a) reported the complete description of medusa development. Male medusae reached maturity in five days and did not show any morphological differences compared to females, the only detected difference between males and females was the life span (shorter in males) (Denitto et al. 2007).

References. Hartlaub (1911) as Bougainvillia muscus var. nana ; Denitto et al. (2007a).

Figures

FIGURE 3. Bougainvillia nana: A, hydranth with medusa bud; B, newly released medusa; C, adult medusa (A, B, C redrawn and modified after Denitto et al. 2007 a by A. Gennari). Scale bars: A, B, 0.5 mm; C, 1.0 mm.