Species of Symplectoscyphus Marktanner-Turneretscher, 1890 (Cnidaria: Hydrozoa, Sertulariidae) from recent Antarctic expeditions with R. V. Polarstern, with the description of four new species Author Peña Cantero, A. L. text Journal of Natural History 2002 36 1509 1568 journal article 1464-5262 Symplectoscyphus so ae sp. nov. (gures 13, 14; table 13) Material examined. ANT VIII-5 Stn 16-421, one stem ca 75 mm high, with gonothecae ( holotype , RMNH-Coel. 29 198, slide 4843); ANT VIII-5 Stn 16-423 , several stems up to 20 mm high, on Billardia sp. (RMNH-Coel. 29 199, slide 4844). 2014 February 13 38: 23 at] Bath of University [by Downloaded FIG. 13. Symplectoscyphus so ae sp. nov.: colony from ANT VIII-5 Stn 16-421 (holotype). Scale bar: 10 mm. Description. Colony composed of a discoidal hydrorhiza giving rise to an erect, branched stem ca 75 mm high and polysiphonic over almost its total length (gure 13). Stem giving rise to branches irregularly arranged in approximately one plane, sometimes with alternate arrangement (gure 13). Some branches distinctively longer, also polysiphonic and bearing lower order branches (gure 13). Hydrothecal internodes either straight or slightly geniculate (gure 14A, B). Hydrothecae alternately arranged in one plane (gure 14A, B); usually one hydrotheca per internode. Occasionally, however, internodes with two hydrothecae present, though in this situation second hydrotheca situated at the place usually occupied by the gonothecae. Hydrotheca cylindrical, but markedly curved abcaudally (gure 14A–E). Adcauline hydrothecal wall typically adnate to internode for more than half its length. Free part of adcauline wall straight or slightly convex. Abcauline wall concave. Cusps of hydrothecal aperture sharp, separated by deep embayments (gure 14A–E). Hydrothecal rim with numerous renovations. Immature gonotheca cone-shaped, truncated distally and with maximum diameter at distal end. Gonothecal walls provided with six/seven rings (gure 14F). Remarks. Though the Polarstern material has only immature gonothecae, we found colonies of Symplectoscyphus so ae sp. nov. in the Antarctic material collected 2014 February 13 38 : 23 at ] Bath of University [ by Downloaded by several Russian expeditions (unpublished data), provided with mature gonothecae. These are oval, provided with a trimming of approximately ten rings and a funnel-shaped neck ( ca 120 m m long) bearing the aperture ( ca 150 m m diameter). The gonothecae are ca 1400 m m long and ca 640 m m width. FIG. 14. Symplectoscyphus so ae sp. nov.: (A, B) two fragments of branches showing hydrothecal arrangement; (C) branching; (D, E) hydrothecal internodes; (F) immature gonotheca. (A–C, F from ANT VIII-5 Stn 16-421; D, E from ANT VIII-5 Stn 16-423.) Scale bar: 500 m m. Symplectoscyphus so ae sp. nov. shares with most of the species of the genus the Table 13. Measurements of Symplectoscyphus so ae sp. nov. (in m m). 2014 February 13 38: 23 at] Bath of University [by Downloaded Internodes Length 600–680 Diameter 200–230 Hydrothecae Length abcauline wall 370–390 Length free part of adcauline wall 180–300 Length adnate part of adcauline wall 270–320 Maximal diameter 160–170 Diameter at aperture 130–150 Gonothecae Length 720 Maximal diameter 720 shape of the gonotheca, since the gonotheca has a pattern of rings. Colonial structure and hydrothecal shape and size, however, distinguish it as a new species. The colonial structure of Symplectoscyphu s so ae sp. nov., characterized by erect and polysiphonic stems, is similar to that found in S. cumberlandicus (Jäderholm, 1905) . However, they are clearly distinguishable by hydrothecal shape and size. Concerning the latter, the hydrothecae are much larger (e.g. 430–550 m m abcauline length and 190–240 m m diameter at the aperture) in S. cumberlandicus whereas the hydrothecae are almost straight and provided with large and sharp cusps. The diVerences from the remaining Antarctic species of the genus are larger, since they include both colony structure and hydrothecal shape and size. From S. anae sp. nov. , S . frigidus sp. nov. , S. glacialis , S. hero , S. naumovi and S. plectilis , it also diVers in shape of the gonotheca. Symplectoscyphus so ae sp. nov. resembles the material identi ed by Ritchie (1913) as S. cumberlandicus . They share colonial structure, hydrothecal size and shape of the gonotheca. However, the gonothecae described by Ritchie are distinctly larger than those present in S. so ae sp. nov. and are also larger than those found in the type material of S. cumberlandicus (cf. table 3). On the other hand, they also share the presence of accessory hydrothecae arising at the position usually occupied by the gonothecae. Ritchie’s material should be re-examined to determine whether it belongs to S. cumberlandicus or to S . so ae sp. nov. Ecology and distribution. Symplectoscyphus so ae sp. nov. was collected at depths from 420 to 470 m . It has been found growing epibiotic on hydroids ( Billardia sp. ) and is used as substratum by other hydroids (campanulinids). The colony with immature gonothecae was collected in January. The material comes from the east coast of the Weddell Sea (oV McDonald Ice Rumples ) . Etymology. We dedicate this species to Dr So a Stepan’yants, St Petersburg , Russia , for her important contributions to the taxonomy of Antarctic hydroids.