Halecium petrosum Stechow 1919
Creators: name: Gravili, Cinzia
name: Vito, Doris De
name: Camillo, Cristina Gioia Di
name: Martell, Luis
name: Piraino, Stefano
name: Boero, Ferdinando
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Cnidaria
Hydrozoa
Leptothecata
Haleciidae
Halecium
Halecium petrosum

description: Halecium petrosum Stechow, 1919
Fig. 65 A–D
See Schuchert (2005b) for a complete synonymy.
Material examined. HCUS-S 0 72 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula). Description (based on our own observations; Schuchert 2005b):
Hydroid. Colonies erect; hydrocauli stiff, monosiphonic, up to 35 mm, with a thick perisarc; hydrocladia alternate, laterally at the end of each internode; hydrothecae sessile, but adcauline wall not adnate to the axis, walls gradually widening distally, rim not flared, hydrothecal renovations frequent, secondary hydrophore large and with undulated perisarc. Gonothecae: female gonothecae ovoid to spherical, big, aperture apical with 2 hydranths, borne on hydrorhiza or on hydrocauli, male gonothecae sac-shaped, elongated, arising from inside of the hydrotheca or below it.
Cnidome. Atrichous isorhizas.
Habitat type. Littoral and shelf species, but absent from the shallowest infralittoral (Peña Cantero & García Carrascosa 2002; Schuchert 2005b).
Substrate. Algae, other hydroids, Posidonia oceanica, anthozoans, incrusting sponge.
Seasonality. Always present in the western Mediterranean (Llobet i Nadal 1987; Llobet et al. 1991); April, August (De Vito 2006; this study) in Salento waters.
Reproductive period. August (Motz-Kossowska 1911; De Vito 2006; this study); September (Llobet et al. 1991; Coma et al. 1992); October (Stechow 1923; Llobet i Nadal 1987; Llobet et al. 1991; Coma et al. 1992); November (Llobet i Nadal 1987) in the Mediterranean Sea.
Distribution. Endemic to the Mediterranean (Medel & López-González 1996; Bouillon et al. 2004; Schuchert 2005b; Gravili et al. 2008a; Morri et al. 2009).
Records in Salento. Rare at: Otranto (De Vito 2006; Gravili 2006; Gravili et al. 2008a; this study); La Strea (Porto Cesareo) (Ventura 2011).
Remarks. Motz-Kossowska (1911) identified abundant material from Banyuls as Halecium robustum Pieper, 1884. Female gonothecae of Motz-Kossowska’s material differed from typical H. lankesterii, and for this reason Stechow (1919) attributed it to a new species with the name Halecium petrosum.
References. Motz-Kossowska (1911) as H. robustum; Stechow (1919, 1923), Leloup (1934), Picard (1951a, 1958a), Rossi (1961), Llobet et al. (1986, 1991), Llobet i Nadal (1987), García-Carrascosa (1981), Llobet i Nidal (1987), Coma et al. (1992), Medel & López-González (1996), Peña Cantero & García Carrascosa (2002), Bouillon et al. (2004), Schuchert (2005b), De Vito (2006), Gravili et al. (2008a), Morri et al. (2009), Puce et al. (2009), Ventura (2011).
description: Published as part of 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, pp. 1-187 in Zootaxa 3908 (1) on pages 93-94, DOI: 10.11646/zootaxa.3908.1.1, http://zenodo.org/record/242729