Dysactis crassicornis Hertwig, 1882a Actinostola crassicornis : Carlgren 1927 Actinostola excelsa McMurrich, 1893 Actinostola pergamentacea McMurrich, 1893 Actinostola intermedia Carlgren, 1899 Actinostola crassicornis : Fautin 1984 Actinostola intermedia Carlgren, 1899 <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> Rodríguez, Estefanía López-González, Pablo J. Zootaxa 2013 2013-03-11 3624 1 1 100 64PB9 (Hertwig, 1882) Hertwig 1882 [151,642,363,390] Anthozoa Actinostolidae Actinostola Animalia Actiniaria 43 44 Cnidaria species crassicornis  ( Figs. 14, 23–24; Table 10; Appx. 1, 2)    Dysactis crassicornisHertwig, 1882a, b; Hertwig 1888; McMurrich 1893.   Actinostola crassicornis: Carlgren 1927; Carlgren 1949; Riemann-Zürneck 1978a.   Actinostola excelsa McMurrich, 1893; Riemann-Zürneck 1978b.   Actinostola pergamentacea McMurrich, 1893; Riemann-Zürneck 1978a. ?  Actinostola intermedia Carlgren, 1899; Carlgren 1927; Carlgren 1949. non  Actinostola crassicornis: Fautin 1984.  MATERIAL EXAMINED  Polarstern ANT XIX/5: stn. PS61/150(AMNH-4704, 2 specimens); stn. PS61/153(AMNH-4698, 3 specimens).   FIGURE 23.External anatomy of  Actinostola crassicornis(Hertwig, 1882). a) Oral view of living specimen [AMNH-4704]. b) View of the pedal disc and distal margin of the column of living specimen [AMNH-4704]. c–d) Lateral view of preserved specimen [AMNH-4698]. Scale bars: a–d, 30 mm.   FIGURE 24.Cnidae of  Actinostola crassicornis(Hertwig, 1882). a, b, d, g, i) Basitrichs. c) Spirocyst. e, h, j, k) Microbasic p- mastigophores. f) Microbasic b-mastigophore. COMPARATIVE MATERIAL EXAMINED    Dysactis crassicornis(Hertwig, 1882). SMNH-Type-1183. Holotype. “Leg. Challenger,st. 313; 52ºS 68ºW, 55 fm”. Also labelled as  Actinostola (Dysactis) crassicornis(Hertwig, 1882).    Actinostola intermedia  Carlgren, 1899. SMNH-Type-1184. Holotype. “ The Strait of Magellaen, Cap. Vicente,   150 m.Dead shell and stone bottom, Leg. ¿?”.  DIAGNOSIS Pedal disc well developed, flat, to 45 mmdiameter. Column smooth, tough, cylindrical or funnel-shaped, slightly wider distally than proximally, to 43 mmdiameter and 60 mmheight in preserved specimens, not divisible into regions. Oral disc very wide, flat, to 70 mmdiameter. Living specimens with white column; tentacles and oral disc with irregular dark red spots; preserved specimens retain red colour of oral disc and tentacles. Tentacles to 190, restricted to column margin, inner longer than outer ones. Marginal sphincter muscle mesogleal, very weak, diffuse and long. More mesenteries proximally than distally. Mesenteries thin, arranged in five cycles; first and second cycles perfect and sterile, rest imperfect and fertile; fourth and fifth cycles arranged according to the  Actinostolarule (mesenteries of pair developed unequally; one facing the precedent cycle more developed). Retractor muscles weak, diffuse; parietobasilar muscles poorly developed. Longitudinal muscles of tentacles mesogleal. Juveniles internally brooded in coelenteron. Cnidom: Spirocysts, basitrichs, and microbasic b- and p-mastigophores. Relatively large microbasic b-mastigophores in base of outer tentacles, to 56 µm long; mesenterial filaments with basitrichs. For a complete description of  Actinostola crassicornis,see Riemann-Zürneck (1978a). GEOGRAPHIC AND BATHYMETRIC DISTRIBUTION    Actinostola crassicorniswas originally described by Hertwig (1882a, b; 1888) in the southeastern coast of Chile. Subsequently, the geographic range of the species was extended to the southwestern coast of Argentina(McMurrrich 1893; Carlgren 1927; Riemann-Zürneck 1978a). The material from this study considered as  A. crassicornis,has been collected in the sub-Antarctic region, in the northern branch of the Scotia Arc, east of Burdwood Bank, between 277–296 mdepth, a region that encompasses the distribution described by Riemann- Zürneck (1978a) for  A. crassicornis.   Actinostola crassicornisis distributed in the southwestern Atlantic and the sub-Antarctic region, in continental shelf and bathyal depths ( Fig. 14f).  REMARKS Austral species within the genus  Actinostolaare very difficult to distinguish based on traditional morphological characters (Riemann-Zürneck 1978a; Häussermann 2004). Fautin (1984)synonymized five austral species of  Actinostolaas  A. crassicornis(  A. excelsa,  A. pergamentacea,  A. intermedia Carlgren, 1899,  A. chilensis McMurrich, 1904, and  A. clubbiCarlgren, 1927) and identified the Antarctic specimens of the genus that she studied as  A. crassicornis( Fautin 1984). However, the specimens studied by Fautin are the only ones of  A. crassicornisin Antarctic waters. The material of Fautin’s (1984)study needs to be re-examined to confirm her conclusions. We consider here  A. crassicornis sensuRiemann-Zürneck (1978a). This species has a smooth but tough column with short and tough tentacles, and its geographic distribution only reaches sea floors north of the Polar Front. Furthermore, we consider here the identity of  A. intermediaand  A. clubbidubious until further revision. The present study suggests that none of the arguments provided by previous authors (e.g. cnidae, number of tentacles and mesenteries, etc. see Riemann-Zürneck 1978a; Fautin 1984; Häussermann 2004) to establish identities or synonymies of these species are robust. [277,1423,726,751] XIX 43 44 XIX/5 5 [463,634,1904,1928] 150 The Strait of Magellaen 44 45 150 holotype