Mitrocoma annae Haeckel, 1864

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 : 120-121

Mitrocoma annae Haeckel, 1864

Fig. 85 A–D

See Kramp (1961) for a complete synonymy.

Material examined. HCUS-S 0 93 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula)—polyp stage.

Description (based on our own observations; Kramp 1932a, 1957b):

Hydroid. Hydrorhiza linear, creeping; colony stolonal; hydranths with conical hypostome; 12–16 filiform tentacles in a single whorl, without basal intertentacular membranous web; hydrothecae Cuspidella -like, cylindrical, wide, elongated, sessile, arising at irregular intervals from hydrorhiza; operculum pyramidal, with numerous sharp, pointed, triangular flaps meeting centrally, with no clear limits with the hydrotheca. Gonothecae scarcely pedicellate, on hydrorhiza, four times larger than the hydrotheca, with numerous sharp, pointed, triangular flaps meeting centrally, with few medusae (2–3) per gonotheca (F. Boero unpublished observations on material from the Ligurian Sea).

Habitat type. Rocky and/or biogenic banks (depth range: 0–90 m) ( Boero & Fresi, 1986; Morri et al. 1999).

Substrate. Algae and hydroids.

Seasonality. September–February ( Boero & Fresi 1986) in the Ligurian Sea; January–February (Brinckmann- Voss 1987) in the Tyrrhenian Sea; October–November ( Denitto 1996) in the Ionian Sea; September (Mastrototaro et al. 2010); March (this study)

Reproductive period. February ( Boero & Fresi 1986) in the Ligurian Sea.

Medusa. Adult. Umbrella flatter than a hemisphere, 30–40 mm wide, mesoglea thick; manubrium very small, 1/8–1/10 of umbrella diameter; mouth lips fairly short; radial canals and circular canal narrow; gonads linear, sinuous, along distal 1/2–3/4 of radial canals, not reaching circular canal, with a median division; 60–100 conical marginal bulbs; each marginal bulb with one wrinkled marginal tentacle; 3–8 marginal cirri between successive marginal tentacles; 60–100 open statocysts.

Developmental stages. New born medusa with umbrella almost spherical, manubrium very small, 1/3 of subumbrellar cavity, 4 mouth lips; 4 radial canals; 4 perradial tentacular bulbs (2 largers than the others); 4 perradial tentacles (2 longer than the others); 4 cirri between successive marginal tentacles; 4 statocysts.

Cnidome. Atrichous and basitrichous haplonemes.

Distribution. Endemic of Mediterranean Sea (Bouillon et al. 2004; Gravili et al. 2008a).

Records in Salento. Rare at: S.ta Maria al Bagno ( Denitto 1996; Miglietta et al. 2000; Gravili 2006; Gravili et al. 2008a); Porto Cesareo ( Faucci & Boero 2000); S. Maria di Leuca (Mastrototaro et al. 2010).

Remarks. Metschnikoff (1886a) reared the hydroid of this medusa. Gonothecae and medusae not seen in the present study.

References. Kramp (1932a, 1957b, 1961), Boero & Fresi (1986), Brinckmann-Voss (1987), Benović & Lučić (1996), Morri & Bianchi (1999), Faucci & Boero (2000), Bouillon et al. (2004), Gravili (2006), Gravili et al. (2008a), Mastrototaro et al. (2010), Bianchi et al. (2011).

Figures

FIGURE 85. Mitrocoma annae: A, general view of a colony; B, hydrothecae; C, part of colony with hydrotheca and gonotheca; D, newly liberated medusa (drawn by F. Boero). Scale bars: B, 0.1 mm; C, 250 µm; D, 0.5 mm.