Halopteris diaphana ( Heller, 1868 )

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 : 102-103

Halopteris diaphana ( Heller, 1868)

Fig. 72 A–E

See Schuchert (1997) for a complete synonymy.

Material examined. HCUS-S 0 79 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula). Description (based on our own observations; Schuchert 1997):

Hydroid. Hydrorhiza stolonal; colonies erect, pinnate; hydrocauli monosiphonic, unbranched, up to 12 mm, basal parts with a varied number of segments separated by transverse nodes bearing a row of median nematothecae, first segment quadrangular and lacking nematothecae, second segment long, ending in oblique node, with 2 nematothecae on upper side, remainder part of the axis heteromerously segmented, with alternate oblique and transverse nodes; hydrocladia alternate, on apophyses lateral to the hydrothecae, hydrothecate internodes of the main axis and hydrocladia composed of one hydrothecae and 3 nematothecae, one median inferior and 2 laterals, non-hydrothecate segments with 1–2 median nematothecae (usually one on the hydrocladia); hydrotheca cupshaped, walls slightly widening, in the middle of the segment, 1/2 adnate, rim even, aperture at 50º–60º from the axis; nematothecae all two chambered and movable, with adcauline embayment, median inferior nematotheca not reaching the hydrotheca, lateral ones on very short apophyses, just reaching the hydrothecal border. Gonothecae of both sexes on separate colonies, on stem and hydrocladia, with 2 segmented pedicels, female ones evenly curved for its entire length, narrowed basally, with 2–4 basal nematothecae, distal end truncate, with a convex lid, male ones oval, slightly curved, obliquely truncated, with 2 basal nematothecae. Colour: transparent.

Cnidome. Microbasic mastigophores.

Habitat type. From the tidal level to 75 m ( Stechow 1923; García Carrascosa 1981; Boero & Fresi 1986; Morri & Bianchi 1999).

Substrate. Algae, Posidonia , hydroids, bryozoans, sponges, bivalve shells, cirripedes.

Seasonality. January, February, April–October ( Boero & Fresi 1986; Gili 1986; Morri & Bianchi 1999; Peña Cantero & García Carrascosa 2002); from January to December (De Vito 2006; this study) in Salento waters.

Reproductive period. April, June–September (Gili 1986; Boero & Fresi 1986; Morri & Bianchi 1999; Peña Cantero & García Carrascosa 2002); from April to May (De Vito 2006; this study) in Salento waters.

Distribution. Although this species has sometimes been thought to be circumtropical, according to Schuchert (1997), it is actually known only from the Mediterranean and from Brazil. It has recently been reported from Florida ( USA) ( Medel & López-González 1996; Schuchert 1997; Peña Cantero & García Carrascosa 2002; Bouillon et al. 2004; Gravili et al. 2008a; Calder 2013).

Records in Salento. Common at Torre dell'Inserraglio ( Presicce 1991), and Otranto (De Vito 2006; Gravili 2006; Gravili et al. 2008a; Stabili et al. 2008; this study).

Remarks. Halopteris diaphana has a rather complicated taxonomic history and very often other species have erroneously been allocated to this species (for more details see Schuchert 1997). The most characteristic trait of H. diaphana is the cornucopia-shaped female gonotheca.

References. Heller (1868) as Anisocalyx diaphana ; Leloup (1934), Stechow (1923) as T. diaphana ; Broch (1933), Picard (1958a), Riedl (1970) as T. diaphanus ; Boero (1981a, b, 1985), García Carrascosa (1981), Isasi (1985), Boero & Fresi (1986), Riedl (1991), Altuna (1994), Medel & Vervoort (1995), Medel & López-González (1996), Schuchert (1997), Morri & Bianchi (1999), Piraino et al. (1999), Ansín Agís et al. (2001), Peña Cantero & García Carrascosa (2002), Bouillon et al. (2004), De Vito (2006), Gravili (2006), Gravili et al. (2008a), Morri et al. (2009).

Figures

FIGURE 72. Halopteris diaphana: A, part of colony; B, part of hydrocladium with hydrotheca and associated nematothecae; C, particular of hydrotheca and associated nematothecae; D, nematotheca; E, female gonotheca (A, E drawn by L. Basso; B, C, D drawn by C. G. Di Camillo). Scale bars: A, E, 0.5 mm; B, C, 0.1 mm; D, 50 µm.