Orthopyxis mollis ( Stechow, 1919 )

Galea, Horia R., 2007, Hydroids and hydromedusae (Cnidaria: Hydrozoa) from the fjords region of southern Chile, Zootaxa 1597 (1), pp. 1-116 : 86-88

Orthopyxis mollis ( Stechow, 1919)

(fig. 20E, F, table 36)

Clytia mollis Stechow, 1919: 44 , fig. L; 1923: 96.

Campanularia everta Clark, 1876: 253 : pl. 39 fig. 4; Naumov, 1969: 277, fig. 142; Blanco, 1976: 36, pl. 3 fig.4; Vervoort, 1972a: 87, fig. 26A–B.

Orthopyxis mollis: Picard, 1951: 344 , fig. 3

Campanularia ? mollis: Leloup, 1974: 13 , fig. 11.

? Campanularia sp. Millard, 1977: 18 , fig. 5F.

? Campanularia sp. Peña Cantero et al., 2004: 2299 , fig. 1J.

? Campanularia rara Stechow, 1919: 60 , fig. R.

Campanularia tincta: Hartlaub, 1905: 557 , figs D 1, E 1, F 1.

Campanularia tincta var. eurycalyx Hartlaub, 1905: 558 , figs G 1, H 1.

Eucopella crenata: Hartlaub, 1905: 568 , fig. Q 1.

Orthopyxis everta: Nutting, 1915: 67 , pl. 16 figs 6–8.

Orthoyxis hartlaubi El Beshbeeshy, 1991: 100 , fig. 23B–C.

Orthopyxis mollis: Ralph, 1957: 840 , fig. 7E–K; Vervoort & Watson, 2003: 440, fig. 107I–T.

Material examined. Stn. ICA — 13.iii. 2006, 12 m, S146: one fertile colony, epizoic on Symplectoscyphus

subdichotomus. Stn. CCO — 09.iii.2006, S144 (18 m): one sterile colony, epizoic on Symplectoscyphus sp. ; S140 (0–20 m): one fertile colony epiphytic on algae ( MHNG INVE 53428). Stn. CPA — 09.iii. 2005, 15 m, S170: numerous fertile colonies epizoic on Symplectoscyphus subdichotomus . Stn. CPI — 07.iii. 2006, 20 m, S89: one fertile colony epizoic on Bougainvillia pyramidata ( MHNG INVE 53327); S149: one sterile colony, epizoic on Bougainvillia pyramidata .

Type locality. Sète , Mediterranean coast of France .

Description. Tubular, occasionally anastomozing stolon creeping on other hydroids and algae, from which arise pedicellate hydrothecae. Pedicels unbranched, moderately long, indistinctly wrinkled, but provided with a few rings basally (not true annuli). Some pedicels showing distinct traces of breakage and subsequent regeneration by presence of transverse constrictions of perisarc. Hydrothecae long and slender, cylindrical in transverse section, proximally rounded into distinct basal chamber, internally marked by circular ring of thickened perisarc; subhydrothecal spherule present below basal chamber. Rim with 10–12 rounded cusps separated by rounded embayments; renovation of margin frequent. Aperture undulated in frontal view, just under the rim, with embayments slightly bent outwards. Gonothecae ovoid to elongated, slightly compressed laterally, springing from stolon via a short, twisted pedicel; walls of gonotheca smooth; distal end truncated, with circular aperture of moderate size.

Remarks. Vervoort (1972a) included Hartlaub’s (1905) specimens of Eucopella crenata Hartlaub, 1901 in his material identified as Campanularia (Orthopyxis) everta Clarke, 1876 . Later on, Vervoort & Watson (2003) synonymized the latter species with Orthopyxis mollis ( Stechow, 1919) and included Hartlaub’s (1905) specimens of Campanularia tincta Hincks, 1861 . These opinions are also followed here.

The trophosome of Campanularia rara Stechow, 1919 is almost indistinguishable morphologically from O. mollis . However, the lack of gonothecae in Stechow’s (1919) material prevents me from synonymizing the two with certainty. Peña Cantero et al. (2004) and Peña Cantero (2006) described two Antarctic hydroids, both similar, belonging to genus Campanularia ; unfortunately, their material was sterile, but it may prove to be conspecific with O. mollis . Millard (1977) described sterile colonies of Campanularia sp. from the Crozet shelf which entirely fit the morphology of the trophosome of O. mollis , the two probably being conspecific.

The specimens of O. mollis described by Vervoort & Watson (2003) from New Zealand have hydrothecae with unthickened perisarc, and a rim with 10–12 rounded cusps. This is the same as in Vervoort’s (1972a) C. everta Clarke, 1876 . The present material from Chile also has hydrothecae with thin perisarc and a similar number of cusps. In contrast, Hartlaub’s (1905) E. crenata and C. tincta are described and figured with pointed hydrothecal cusps and thickened perisarc. Neverthless, besides the absence of gonothecae in Hartlaub’s (1905) specimens of both species, the general morphology of their trophosome is in agreement with the available descriptions of O. mollis . Nutting’s (1915) hydrothecae of O. everta and Naumov’s (1969) hydrothecae of C. everta are also both described and figured with thickened hydrothecal walls.

The variability of the structure of the hydrothecal wall seems to be a normal rule in this species. Nutting (1915) cited the observations made by Torrey (1902), which are also reproduced here: “The rim of the hydrothecae may or may not be everted. It is usually but not always crenate. The wall of the hydrotheca may be very thick or very thin, and is either straight or convex in profile.”

The gonophore of this species was reported to be a large eumedusoid with four branched radial canals, and occupying the greater part of the gonothecal lumen ( Nutting 1915, Picard 1951, Ralph 1957). The soft parts of gonothecae in present material are poorly preserved and no detailed observations could be made.

World distribution. Pacific coast of North America ( Clark 1876), Tierra del Fuego ( Hartlaub 1905), Atlantic coasts of Argentina ( Blanco 1976, El Beshbeeshy 1991), Strait of Magellan and Falkland Islands ( Vervoort 1972a), Mediterranean ( Stechow 1919), Russia, Sea of Japan ( Naumov 1969), New Zealand ( Ralph 1957, Vervoort & Watson 2003), Antarctica (Peña Cantero & García Carrascosa, 1999).

Records from Chile. This species was previously reported from Tocopilla ( Leloup 1974). The present material was found between 49°11' S and 50°50' S .