Laodicea undulata (Forbes and Goodsir, 1851)

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 : 114-115

Laodicea undulata (Forbes and Goodsir, 1851)

Fig. 81 A–E

See Russell (1953) and De Vito et al. (2006) for a complete synonymy.

Material examined. HCUS-S 089p and HCUS-S 089m (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula—polyp and medusa stages).

Description (based on our own observations; Russell 1953; Cornelius 1995; De Vito et al. 2006):

Hydroid. Hydrorhiza as creeping stolons; colonies stolonal; hydranth long, very extensile, hypostome tall, conical; 8–14 amphicoronate filiform tentacles in a single whorl, without intertentacular membranous web; hydrothecae Cuspidella -like, cylindrical, sessile, with delicate diaphragm; old hydrothecae with transverse growth rings; with a multi-valve operculum with 12–16 triangular flaps demarcated by a crease line, originating from the upper hydrothecal margin, opercular flaps demarcated by a crease line; gonotheca similar to hydrotheca in shape, but about twice as long, with a tapered basal constriction and multi-valve operculum, without visible growth rings, each with 3–5 medusa buds at differing stages. Gonothecae similar to hydrotheca, but about twice as long, with a basal constriction and multi-valved operculum, without visible growth rings, each with 3–5 medusa buds at differing stages.

Habitat type. Rocky substrate, Posidonia (depth range: 10–170 m of depth) ( Russell 1957; Boero & Fresi, 1986; Ramil & Vervoort 1992; De Vito et al. 2006).

Substrate. Several organisms such as Posidonia , hydroids, Scalpellum sp. (barnacle), algae (often on the underneath side of Peyssonnelia spp.), sponges, anthozoans, bryozoans, shells.

Medusa. Adult. Umbrella slightly flatter than a hemisphere, up to 37 mm wide; manubrium short, with square base and short perradial lobes; mouth with short, slightly folded, crenulated, recurved lips; 4 simple radial canals; circular canal narrow; gonads elongated, with sinuous pendent folds issuing from corners of manubrium along perradial lobes and half part of radial canals or almost to umbrella margin, gonads may be developed even in small specimens and the same individual may present more than one sexual cycle; up to 400–600 faintly developed marginal tentacular bulbs, small abaxial spurs on young marginal bulbs, often absent in adults ones; each marginal bulb with one hollow marginal tentacle; 1–2 spiral cirri (often lost by preservation) between tentacles; usually 1 cordylus between marginal bulbs; ocelli on each third or fifth tentacle when adult, on each tentacle when juvenile. Colour: ocelli black.

Developmental stages. Newly released medusa with bell-shaped umbrella, diameter ≤ 1 mm; 4 marginal tentacular bulbs; 2–4 tentacles; without ocelli; after 10–11 days they develop 2 additional tentacles and 1–2 spiral cirri on each inter-tentacular quadrant along the bell margin; the cordyli develop only after the formation of cirri.

Cnidome. Holotrichous and basitrichous isorhizas.

Seasonality. January–December (De Vito 2006; this study) in Salento waters.

Reproductive period. October (De Vito 2006; this study) in Salento waters.

Distribution. Atlantic, Indo-Pacific?, Mediterranean ( Medel & López-González 1996; Bouillon et al. 2004; De Vito et al. 2006; Gravili et al. 2008a).

Records in Salento. Rare at: Otranto Torre Inserraglio, Nardò (De Vito 2006; De Vito et al. 2006; Gravili 2006; Gravili et al. 2008a; Piraino et al. 2013; this study); S. Maria di Leuca (Mastrototaro et al. 2010).

Remarks. The whole cycle was examined in the present study. Laodicea undulata is the commonest Laodicea species in the Mediterranean Sea, and possibly is the only valid species of the genus. In fact, the occurrence of L. fijiana Agassiz and Mayer, 1899 in the Mediterranean Sea is questionable, and doubts about the validity of L. ocellata Babnik, 1948 are still unresolved. Laboratory rearing of L. undulata medusae led to the discovery of their potential for life cycle reversal: the medusa stage of this species can asexually transform back into the polyp stage (for details see De Vito et al. 2006).

References. Mayer (1910) as Laodicea cruciata ; Ranson (1933), Russell (1936, 1953, 1957), Hure (1955), Trégouboff & Rose (1957), Picard (1958a), Kramp (1959, 1961), Dekeyser & Derivot (1961), Rossi (1971), Repetto et al. (1977), Bouillon et al. (1991), Riedl (1991), Ramil & Vervoort (1992), Medel & López-González (1996), Mills et al. (1996), Buecher & Gibbons (1999), Bouillon et al. (2004), Touzri et al. (2004), Benović et al. (2005), De Vito (2006), De Vito et al. (2006), Gravili (2006), Batistić et al. (2007), Galea (2007), Gravili et al. (2008a), Puce et al. (2009), Mastrototaro et al. (2010), Piraino et al. (2013).

Figures

FIGURE 81. Laodicea undulata: A, polyp; B, hydrotheca with a multi-valve operculum; C, gonotheca and medusa buds; D, newly liberated medusa with two or E, four tentacles (D and E same scale bar) (modified after De Vito et al. 2006). A, 600 µm; B, 250 µm; C, 500 µm; D, E, 1.0 mm.