Monotheca obliqua (Johnston, 1847)

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 : 121-123

Monotheca obliqua (Johnston, 1847)

Fig. 86 A–C

See Peña Cantero & García Carrascosa (2002) for a complete synonymy.

Material examined. HCUS-S 0 94 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula).

Description (based on our own observations; Cornelius 1995; Peña Cantero & García Carrascosa 2002):

Hydroid. Hydrorhiza only slightly branched; colonies erect, up to 40 mm; hydrocaulus zigzag, with distinct internal ribs, internodes slightly curved, each bearing a latero-distal apophysis, with 1–2 nematothecae at the level of the apophysis insertion and another nematotheca on the segment; hydrocladia borne on the apophyses, each comprising a basal athecate internode and another with one hydrotheca surrounded by 3 nematothecae, one median inferior reaching the base of the hydrotheca and 2 immediately above and behind hydrotheca; hydrothecal compartments not swollen distally; hydrothecae cup-shaped, entirely adnate, rim even but sinuous, aperture at right angle with the internode; nematothecae 2-chambered, basal chamber narrow, tubular, distal chamber cup-shaped. Gonothecae: male ovate, narrowing at ends, apical aperture small, female cylindrical, truncate distally, tapering basally, borne on stem below hydrothecae.

Cnidome. Microbasic mastigophores.

Habitat type. Rocks, cave, from the tidal level to 70 m depth (García Carrascosa 1981; Boero & Fresi 1986; Roca 1986).

Substrate. Epibiontic on several organisms such as algae, hydroids, bryozoans, and cirripedes; Gili (1986) found it also on rocks.

Seasonality. January–June, October, December (for a review see Bouillon et al. 2004); December, April (De Vito 2006; this study) in Salento waters.

Reproductive period. February, May–October (Bouillon et al. 2004) in the Mediterranean Sea.

Distribution. Cosmopolitan ( Stechow 1919; Picard 1955; Boero & Fresi 1986 as P. obliqua ; Medel & López- González 1996; Morri et al. 1999; Peña Cantero & García Carrascosa 2002; Bouillon et al. 2004; Bianchi et al. 2011 as P. obliqua ; Soto Ãngel & Peña Cantero 2013).

Records in Salento. Moderately frequent at: Costa Merlata ( Fraschetti et al. 2002); Grotta del Ciolo ( Moscatello & Belmonte 2007); Il Chiapparo, Otranto (De Vito 2006; Gravili 2006; Gravili et al. 2008a; this study).

Remarks. Colonies living on Posidonia oceanica leaves have been ascribed to a distinct species (see under Monotheca posidoniae ).

References. Stechow (1919); Billard (1923) and Broch (1933) both as Plumularia obliqua ; Picard (1955, 1958a) as M. posidoniae ; Riedl (1966) as Monotheca heteronoma and M. obliqua ; García Carrascosa (1981); Boero & Fresi (1986); Gili (1986), Roca (1987) all as P. obliqua ; Cornelius (1995); Medel & López-González (1996); Morri & Bianchi (1999) as P. obliqua ; Morri et al. (1999); Piraino et al. (1999) as P. obliqua ; Fraschetti et al. (2002); Peña Cantero & García Carrascosa (2002); Bouillon et al. (2004); De Vito (2006), Gravili (2006); Moscatello & Belmonte (2007); Gravili et al. (2008a); Bianchi et al. (2011) as P. obliqua .

Figures

FIGURE 86. Monotheca obliqua: A, general aspect of a colony; B, part of colony; C, hydrotheca and associated nematothecae (drawn by C. G. Di Camillo). Scale bars: A, 1 mm; B, C, 250 µm.