Clytia hemisphaerica (Linnaeus, 1767)

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 : 142-143

Clytia hemisphaerica (Linnaeus, 1767)

Fig. 101 A–D

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

Material examined. HCUS-S 108p and HCUS-S 108m (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula)—polyp and medusa stages.

Description (based on our own observations; Cornelius 1995; Schuchert 2001a):

Hydroid. Hydrorhiza as a creeping stolon system; colonies usually stolonal but occasionally erect; hydrothecal pedicels borne at close intervals, straight, with one to several rings at top and bottom and in some specimens also centrally, sometimes forking, secondary pedicels having characteristic upward curved basal region; hydranths 3–4 times as long as broad when fully extended; with usually 24–30 amphicoronate tentacles; hydrothecae campanulate, diaphragm thin, rim with ca 8–14 broad rounded-triangular cusps. Gonothecae tubular, with wide opening, walls smooth in some specimens but typically with trasverse folds arising from hydrorhiza on short, slender pedicels.

Cnidome. b-mastigophores, 2 types (polyp), isorhizas (medusa).

Habitat type. Clytia hemisphaerica is a eurybathic species that, in the Mediterranean, has been found from the tidal level to about 140 m depth ( Broch 1933; Boero & Fresi 1986; Roca 1986); records from the Baltic ( Cornelius 1995) indicate tolerance to brackish water.

Substrate. Algae, phanerogams, hydrozoans, other invertebrates, floating objects.

Seasonality. January–December ( Boero & Fresi 1986; Puce et al. 2009; De Vito 2006; this study) in the Mediterranean Sea.

Reproductive period. January ( Stechow 1923; Boero & Fresi 1986; Puce et al. 2009), February ( Stechow 1923; Picard 1951a; Gili 1986; Boero & Fresi 1986; De Vito 2006; Puce et al. 2009; this study), March ( Stechow 1923; Rossi 1961; Roca 1986; Boero & Fresi 1986; De Vito 2006; Puce et al. 2009; this study), April ( Stechow 1919; Picard 1955; Roca 1986; De Vito 2006; Puce et al. 2009; this study), May ( Stechow 1919; Gili 1986; Roca 1986; Piraino & Morri 1989; De Vito 2006; Puce et al. 2009; this study), June ( Stechow 1919; Roca 1986; Morri & Bianchi 1999; De Vito 2006; this study), July ( Peña Cantero & García Carrascosa 2002; De Vito 2006; this study), August ( Boero & Fresi 1986; Peña Cantero & García Carrascosa 2002; De Vito 2006; Puce et al. 2009; this study), September ( Boero & Fresi 1986; De Vito 2006; Puce et al. 2009; this study), October ( Boero & Fresi 1986; Puce et al. 2009), November ( Rossi 1961; Boero & Fresi 1986; Piraino & Morri 1989; Puce et al. 2009), and December ( Boero & Fresi 1986; Puce et al. 2009) in several localities of the Mediterranean Sea.

Medusa. Adult. Umbrella nearly hemispherical or flatter, up to 20 mm wide, mesoglea fairly thin; manubrium small, quadrate, with small base; 4 simple lips; usually 4 straight radial canals (sometimes more, up to 12); gonads oval or linear, 1/2–3/4 of length of radial canals without median furrow, nearer to margin than to manubrium; velum narrow; typically 32 (16–58) marginal tentacular bulbs, globular, prominent, each with one tentacle, also with few partially developed marginal bulbs; 1–3 usually 2 statocysts between successive tentacles. Colours: coloration varied, marginal tentacle bases and stomach yellowish, yellow brown, reddish brown, greenish or purple; gonads yellowish.

Developmental stages. The size range for medusae and the numbers of tentacles, including developing bulbs, vary depending on the seasonal variation; in the spring and early summer the medusae grow to a larger size than at other times of the year (for more details see Russell 1938).

Distribution. Polyp nearly cosmopolitan in temperate waters of all oceans ( Fraser 1944; Naumov 1969; Marinopoulos 1979; Cornelius 1995; Medel & López-González 1996; Schuchert 2001a; Peña Cantero & García Carrascosa 2002; Bouillon et al. 2004; Gravili et al. 2008a; Soto Ãngel & Peña Cantero 2013).

Records in Salento. Common at: Torre dell’Inserraglio, Torre S. Emiliano, La Rotonda, Porto Badisco, Marina di Corsano, Palude del Capitano, Torre Vado ( Presicce 1991); Otranto (De Vito 2006; Gravili 2006; Gravili et al. 2008a; Ventura 2011; Piraino et al. 2013; this study); Torre Lapillo, S.ta Caterina ( Andreano 2007); La Strea (Porto Cesareo) ( Andreano 2007; Ventura 2011); Il Chiapparo (C. Gravili unpublished observations).

Remarks. The whole life cycle was examined in the present study. Clytia hemisphaerica can be difficult to identify in the absence of gonothecae, when it is often confused with C. gracilis (for more details see Cornelius 1995). Reports about medusae with multiple radial canals might be referred to Clytia gracilis (see above). Many supposed variations of this species might be referrable to other, distinct species.

References. Lo Bianco (1909), Mayer (1910) as Phialidium hemisphaericum ; Hadzi (1911) as Clythia johnstoni ; Neppi & Stiasny (1911, 1913) as Thaumantias hemisphaericum ; Broch (1912, 1933 as Campanularia (Phialidium) johnstoni f. typica and f. crassa), Neppi (1912, 1918, 1919, 1920), Pell (1918, 1938), Stechow (1919, 1923), Kramp (1924, 1961), Vatova (1928), Billard (1931, 1936), Ranson (1933), Leloup (1934), Babnik (1948), Picard & Roch (1949), Rossi (1950, 1961, 1971), Picard (Picard 1951a, 1952, 1958 a), Russell (1953), Trégouboff & Rose (1957), Tortonese (1958), Riedl (1959, 1970, 1991), Rossi (1961), Goy (1973), Schmidt (1973), Chimenz Gusso & Rivosecchi Taramelli (1976), Montanari & Morri (1977), Relini et al. (1977), Repetto et al. (1977), Morri (1979c, 1980b, 1981a, b, 1985), Relini et al. (1979), Boero (1981a, b, c), García Carrascosa (1981), Fresi et al. (1982), Morri & Bianchi (1982, 1983), Boero et al. (1985), Bavestrello (1985), Boero et al. (1985), Boero & Fresi (1986), Gili (1986), Llobet et al. (1986, 1991), Benović & Bender (1987), García-Rubies (1987, 1992), Llobet i Nidal (1987), Östman et al. (1987), Roca (1987), Goy et al. (1988, 1990, 1991), Ramil (1988), Piraino & Morri (1989, 1990), Morri et al. (1991), Roca et al. (1991), Morri et al. (1992), Bianchi et al. (1993a, b), Altuna (1994), Benović & Lučić (1996), Migotto (1996), Mills et al. (1996), Medel & López-González (1996), Morri & Bianchi (1999), Piraino et al. (1999), Medel & Vervoort (2000), Peña Cantero & García Carrascosa (2002), Bouillon et al. (2004), Benović et al. (2000, 2005), Milos & Malej (2005) as P. hemisphaericum ; De Vito (2006), Gravili (2006), Batistić et al. (2007), Galea (2007), Gravili et al. (2008a), Morri et al. (2009), Puce et al. (2009), Touzri et al. (2010), Giovannetti et al. (2010), Bianchi et al. (2011), Ventura (2011), Piraino et al. (2013).

Figures

FIGURE 101. Clytia hemisphaerica: A, hydranth and gonotheca; B, diagram of hydrothecal rim; C, young, and D, fully-grown medusa (drawn by C. G. Di Camillo). Scale bars: A, 0.5 mm; C, 1.0 mm; D, 6.0 mm.