Schizotricha nana Peña Cantero, Svoboda and Vervoort, 1996

Peña Cantero, A. L. & Vervoort, W., 2005, Species of Schizotricha Allman, 1883 (Cnidaria: Hydrozoa: Halopterididae) from US Antarctic expeditions with the description of two new species, Journal of Natural History 39 (11), pp. 795-818 : 808

Schizotricha nana Peña Cantero, Svoboda and Vervoort, 1996

Schizotricha nana: Peña Cantero and Vervoort 1999, p 367 (synonymy).

Material examined. 000AF, one incipient stem ca 11 mm long ( USNM 1025581); 12/1001, one stem ca 175 mm high, with gonothecae ( USNM 1025582; RMNH-Coel. 30945; MNCN 2.03/324); 12/1002, one hydrocladium ( USNM 1025583); 12/1003, one fragmented stem (largest fragment ca 110 mm long), with gonothecae ( USNM 1025584; RMNH-Coel. 30946; MNCN 2.03/325); 27/1869, a few stem fragments up to 60 mm long ( USNM 1025585); 32/1996, one distal fragment ca 6 mm long ( USNM 1025586); 32/ 2054, one stem fragment composed of only two cauline internodes (in slide) ( USNM 1025587); 32/2120, several fragments and stems up to 95 high ( USNM 1025588; RMNH- Coel. 30947; MNCN 2.03/326); 32/2121, seven stem fragments up to 43 mm long ( USNM 1025589); 575/061, one fragmented and branched stem (largest fragment ca 130 mm long), with gonothecae ( USNM 1025590; RMNH-Coel. 30974; MNCN 2.03/ 327); 575/067, one fragmented stem at least 150 mm high ( USNM 1025591; RMNH- Coel. 30953; MNCN 2.03/328); 575/070, numerous fragments up to 165 mm long, with gonothecae ( USNM 1025592; RMNH-Coel. 30954; MNCN 2.03/329); 575/071, several fragments and stems up to 220 mm high ( USNM 1025593; RMNH-Coel. 30955; MNCN 2.03/330); 575/073, several stem fragments up to 90 mm long, almost without hydrocladia ( USNM 1025594).

Diagnosis. Colonies with branched stems. Main cauline tube with single hydrothecate internodes with one or two infrathecal nematothecae. Hydrocladia up to second order. Hydrocladia heteromerously divided into internodes; with ahydrothecate internode, provided with one nematotheca, following cauline and hydrocladial apophyses. Unforked hydrocladial internodes with one infrathecal nematotheca. Hydrotheca low. Forked hydrocladial internodes with one infrathecal nematotheca.

Ecology and distribution. Schizotricha nana had previously been considered a shelf species (Peña Cantero et al. 1996), being known from depths between 43 ( Stepan’yants 1972) and 385 m ( Vanhöffen 1910) on sandy, stony and rocky bottoms ( Stepan’yants 1979). Our present material comes from 91 to 1890 m, once occurring on gravel, considerably increasing the bathymetric range which now reaches bathyal depths. Peña Cantero et al. (1996) reported fertile colonies in January and February, whereas we observed gonothecae in colonies collected in March, May and June. We found colonies of Billardia sp., Campanularia sp., Clytia sp., Eudendrium sp., Halecium sp., Lafoea sp. and Symplectoscyphus sp. epibiotic on S. nana .

Schizotricha nana has a circum-Antarctic distribution (Peña Cantero et al. 1996), being known from both East and West Antarctica. In the former it has been recorded at Gauss Station (65 u 219S–86 u 069E) ( Vanhöffen 1910), in the Davis Sea ( Briggs 1938; Stepan’yants 1972) and off Adélie Coast ( Naumov and Stepan’yants 1972). In West Antarctica it has been reported from the eastern part of the Weddell Sea (Peña Cantero et al. 1996) and in the South Shetland Islands area (cf. Peña Cantero and Vervoort 1999). Our material comes from off Budd Coast (Wilkes Land), Cape Adare and Pennell Coast (Victoria Land), and from Moubray Bay (Ross Sea), in East Antarctica, and from NE of Joinville Island (Antarctic Peninsula), off Elephant Island (South Shetland Islands), and off Visokoi and Zavodovski Islands ( South Sandwich Islands), in West Antarctica.