Sphaeronectes irregularis, C. Carre, 1968

P. R. Pugh, 2009, A review of the family Sphaeronectidae (Class Hydrozoa, Order Siphonophora), with the description of three new species, Zootaxa 2147, pp. 1-48 : 46-47

Sphaeronectes irregularis (Claus 1873, 1874) (see Figures 16 & 17)

Monophyes irregularis Claus, 1873, p. 259 ; 1874, p. 32, Pl. 4, figs. 5–6, 15–18; Chun, 1888, p. 1154; Haeckel, 1888b, p. 128; Chun, 1892, p. 82; 1897b, p. 102; Trégouboff & Rose, 1957, p. 372, [non Pl. 83, fig. 11 copy of Sphaeronectes brevitruncata (Chun, 1888) ].

Diplophysa sp. Claus, 1874 , p.27, P1.4 figs. 5–7.

Diplophysa truncata Haeckel, 1888a, p. 32 (in partim).

Sphaeronectes truncata Schneider 1898, p. 78 (in partim).

Sphaeronectes irregularis C. Carré, 1968c, p. 86 , Pl. I, fig. 3, Pl. II, figs. 5–6; D. Carré, 1969, p. 34, Pl. I, figs. 9–11.

? Ersaea truncata Will, 1844, p. 82 , Pl. 2 figs. 28, 29, 31; Moser, 1925, p. 97.

? Diplophysa inermis Gegenbaur, 1853, p. 291 , Pl. 16 fig. 3; Fewkes, 1881, p. 166, Pl. 6 fig. 12; Haeckel, 1888b, p. 107; Chun, 1892, p. 85.

? Praya inermis Metschnikoff, 1874, p. 46 , Pl. 7, fig. 16.

? Sphaeronectes ptacilis Vanhoeffen, 1906, fig. 13 [copy of Fewkes, 1881, Pl. 6, fig. 12 as Diplophysa inermis ].

? Sphaeronectes köllikeri Trégouboff & Rose, 1957 , Pl. 76, fig. 10 [copy of Fewkes, 1881, Pl. 6, fig. 12 as Diplophysa inermis ].

? Sphaeronectes irregularis Gamulin & Kršinić, 2000 , text-fig. 81.

? Sphaeronectes gracilis [eudoxid] Bouillon et al., 2004, fig. 142F; 2006, fig. 231F [copy of Fewkes, 1881, Pl. 6, fig. 12

as Diplophysa inermis ]. non Sphaeronectes irregularis Moser, 1925, p. 93 , text-fig. 19 [copy of Sphaeronectes brevitruncata (Chun, 1888) ];

Stepanjants, 1967, text-fig. 53(I); 1973, text-fig. 1A [copy of Sphaeronectes brevitruncata (Chun, 1888) ]; Daniel,

1985, p. 293, text-fig. 78b [= S. koellikeri ]; Bouillon et al., 2004, Fig. 142G [copy of Sphaeronectes brevitruncata

(Chun, 1888)]. non Sphaeronectes irregularis var. C. Carré, 1968c, Pl. I, fig. 2 [= Sphaeronectes brevitruncata (Chun, 1888) ].

Distribution: The records for Sphaeronectes irregularis are far fewer than those for S. koellikeri , and mostly come from the Mediterranean, from whence it was first described (see Gamulin & Kršinić, 2000), with the great majority of specimens having been collected within the top 200 m of the water column. It often co-occurs with S. koellikeri but in considerably fewer numbers. The records for S. irregularis by Chun (e.g. Chun, 1892) from the Canary Islands appear to be the only published ones for the whole of the Atlantic Ocean. However, it has been collected by SCUBA divers off Bermuda (Pugh, personal data), and Margulis (1992) maps an unpublished record from Josephine Bank (c. 36°N, 14°W).

For the Pacific Ocean there are again numerous records from off Chile (e.g. Apablaza & Palma, 2006; Palma, 2006, and references therein), and Kitamura et al. (2003) have recorded it off Japan, but there are no records for the China Sea. Margulis (1992), in her Figure 2, shows many records for the South-East Pacific, but the only record for the North-East Pacific appears to come from Margulis & Vereshchaka (1988) from off California, although the exact position is unclear.

This last record again raises the question as the accuracy of identification as, like Sphaeronectes koellikeri , S. irregularis has not been collected by SCUBA divers off California. Of the six Sphaeronectes species , excluding the new ones described herein, only S. koellikeri can be readily distinguished by the shape of its hydroecium, extending over the top of the nectosac, and the straight radial canals all arising together from the pedicular canal. All the other species have a relatively small hydroecium confined to the ventral side of the nectophore and, apart from S. bougisi , looped lateral radial canals. The shape of the somatocyst and the size of the nectophore are then the main characters distinguishing the species. However, the differences between the structures of the somatocyst for what are obviously distinct species can be slight. Thus I am inclined to believe that the record for S. irregularis given by Margulis & Vereshchaka (1988) for off California actually pertains to another species. The same also probably applies to the records of S. irregularis given by Margulis (1992) for the Antarctic Sector of the Indian Ocean. These, as noted above, may well belong to the new Sphaeronectes species mentioned by Pagès & Kurbjeweit (1994) and Pagès & Schnack-Schiel (1996) from the Weddell Sea (Atlantic Sector of the Antarctic Ocean). Margulis (1992) Figure 2 also shows the presence of " S. irregularis " off New Zealand and to the south of Tasmania.

Margulis (1992) also records Sphaeronectes irregularis in the Indian Ocean, in the region of the Maldives, and Patriti (1970) has found it off Madagascar. Daniel (1985) has also recorded the species from the Bay of Bengal but, judging by her illustration (ibid, Fig. 78b), she may actually have been referring to S. koellikeri .