Stephanthus antarcticus Rodríguez & López-González, 2003

Rodríguez, Estefanía & López-González, Pablo J., 2013, <strong> New records of Antarctic and Sub-Antarctic sea anemones (Cnidaria, Anthozoa, Actiniaria and Corallimorpharia) from the Weddell Sea, Antarctic Peninsula, and Scotia Arc </ strong>, Zootaxa 3624 (1), pp. 1-100 : 36-38

Stephanthus antarcticus Rodríguez & López-González, 2003

( Figs. 14 , 18 ; Appx. 1, 2)

Stephanthus antarcticus Rodríguez & López-González, 2003 .

MATERIAL EXAMINED

Polarstern ANT XV/3: stn. PS48/336 ( ZMH: C-11680, Holotype; ZMH: C-11681, paratype; KUNHM- 001610, paratype) .

Polarstern ANT XIX/3 : stn. PS61/103-1 ( BEIM: ANT-1282, 1 specimen) ; stn. PS61/106-1 ( BEIM: ANT- 1281, 1 specimen) ; stn. PS61/107-1 ( BEIM: ANT-1609, 1 specimen) .

Polarstern ANT XXIII/8 : stn. PS69/689-3 (AMNH-6000, 1 specimen); stn. PS69/726-4 (AMNH-5015, 1 specimen) .

DIAGNOSIS

Aboral rounded, physa-like. Column not differentiated into regions, elongated or more or less ovoid, but with a parapet and deep fosse, to 40 mm diameter and 56 mm height in preserved specimens. Column smooth, corrugated in preserved specimens; larger specimens with non-adherent pale spots proximally. Column beige with irregular orange spots in living specimens, tentacles whitish; preserved specimens pink to tan. Tentacles long, only partially retracted, to 24, arranged in three cycles. Marginal sphincter muscle absent. Equal number of mesenteries proximally and distally. Mesenteries to 12 pairs, arranged in two cycles, only first cycle perfect but both fertile. A single, strong siphonoglyph, enlarged proximally. Retractor muscles diffuse at the actinopharynx level, restricted distally; parietobasilar muscles well developed, strong. Cnidom: Spirocysts, basitrichs, and microbasic b - mastigophores. Basitrichs in the tentacles very long, to 107 mm. For a complete description of Stephanthus antarcticus , see Rodríguez & López-González (2003).

GEOGRAPHIC AND BATHYMETRIC DISTRIBUTION

Stephanthus antarcticus is only known off the South Shetland Islands (near Antarctic Peninsula); lives burrowed in soft bottoms between 256– 1,227 m depth ( Rodríguez & López-González 2003). Additional material from this study was collected in Joinville and Seymour islands (Antarctic Peninsula) between 213–292 m depth.

Stephanthus antarcticus is an Antarctic endemic species, inhabiting continental shelf and bathyal depths ( Fig. 14c ).

Family LIPONEMATIDAE Hertwig, 1882

Genus Liponema Hertwig, 1882

Figures

FIGURE 14. Distribution map of species. a) Isotealia antarctica Carlgren, 1899. b) Capnea georgiana (Carlgren, 1927). c) Stephanthus antarcticus Rodríguez & López-González, 2003. d) Liponema multiporum Hertwig, 1882. e) Dactylanthus antarcticus (Clubb, 1908). f) Actinostola crassicornis (Hertwig, 1882). Green triangles, type locality; green circles, previous localities; red circles, localities from this study; yellow circles, localities from this study from underwater photography survey; dark line, Subtropical Front; light line, Polar Front.

FIGURE 18. External anatomy of Stephanthus antarcticus Rodríguez & López-González, 2003. a–b) View of living specimens [AMNH-6000], [BEIM(ANT-1282, 1281, 1609)]). c–d) Lateral view of preserved holotype [ZMH C11680] and paratype [ZMH C11681]. e) Longitudinal section of the distal column and oral disc [ZMH C11680]. f–g) Detail of the proximal column showing non-adherent spots. Scale bars: a–b, d, 10 mm; c, 20 mm; e, 2.5 mm; f–g, 5 mm.