Actinostola georgiana Carlgren, 1927

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 : 46-51

Actinostola georgiana Carlgren, 1927

( Figs. 25–27 ; Table 10; Appx. 1, 2)

Actinostola georgiana Carlgren, 1927 ; Carlgren 1928; Carlgren 1949.

? Actinostola clubbi Carlgren, 1927 ; Carlgren 1949.

MATERIAL EXAMINED

Polarstern ANT XVII/3 : stn. PS56/178-2 (AMNH-4303, 1 specimen; AMNH-4304, 3 specimens; AMNH-4305, 1 specimen; AMNH-4306, 3 specimens; BEIM: ANT-4306, 4 specimens) .

Polarstern ANT XIX/5 : stn. PS61/174 (AMNH-4661, 1 specimen; AMNH-4696, 6 specimens); stn. PS61/ 182 (AMNH-4667, 1 specimen) ; stn. PS61/231 (AMNH-4712, 4 specimens; AMNH-4766, 1 specimen; AMNH- 4767, 4 specimens; AMNH-4768, 1 specimen; BEIM: ANT-4769, 3 specimens) .

Polarstern ANT XXI/2 : stn. PS65/019-1 (AMNH-4790, 3 specimens; AMNH-4791, 1 specimen; AMNH- 4792, 1 specimen; AMNH-4802, 1 specimen; AMNH-4803, 1 specimen) .

TABLE 10. Size ranges of the cnidae of Actinostola crassicornis (Hertwig, 1882) and A. georgiana Carlgren, 1927 ; for comparative cnidae data of the species see Carlgren (1927), Riemann-Zürneck (1978a), Fautin (1984), and Häussermann (2004). Χ: mean. SD: standard deviation. S: ratio of number of specimens in which each cnidae was found to number of specimens examined. N: total number of capsules measured. F: Frequency, +++ = very common, ++ = common, + = rather common, --- = sporadic. Abbreviations: Mc, Microbasic. (*) Mean values based in fewer than 40 capsules.

(1) Named as Mc. b -mastigophores by Riemann-Zürneck (1978a). (2) Data from type material (SMNH-Type-4015)

COMPARATIVE MATERIAL EXAMINED

Actinostola georgiana Carlgren, 1927 . SMNH-Type-4015. Syntypes. Also labelled as: “ Syntypes according to D. Fautin (2002) ” (4 specimens).

Actinostola clubbi Carlgren, 1927 . SMNH-Type-4009. Holotype. “Leg. Discovery Exp., sta. Disc, Antarctic, Oates Land, 67º21’S, 155º21’E, 254 fm. Also labaelled as: “SMNH-Type-4009, according to D. Fautin (2002), A. crassicornis (Hertwig, 1882) ”.

DIAGNOSIS

Pedal disc well developed, flat, to 61 mm diameter. Column smooth, firm, cylindrical or funnel-shaped, slightly wider distally than proximally, to 95 mm diameter and 103 mm height in preserved specimens, not divisible into regions; preserved specimens with corrugated column. Oral disc very wide, flat, to 100 mm diameter. Living specimens white or with a light pink tone, column hyaline in texture; preserved specimens all white to beige. Tentacles relatively long (to 11 mm), to 192, 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 (to six) cycles; first and second cycles perfect and sterile, others imperfect and fertile; fourth and fifth cycles arranged according to the Actinostola rule. Retractor muscles weak and 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 at base of outer tentacles, to 44 µm long; mesenterial filaments without basitrichs. For a complete description of Actinostola georgiana , see Carlgren (1927).

GEOGRAPHIC AND BATHYMETRIC DISTRIBUTION

Actinostola georgiana has been previously collected in the Scotia Sea ( South Georgia Island) and in Bouvet Island, between 250–567 m depth (Carlgren 1927, 1928).

The material from this study confirms the presence of the species in South Georgia and Bouvet Islands, extending its geographic distribution to the South Orkney Islands and to the west of Deception Island (north of Antarctic Peninsula). The depth range of the species is also extended here, to 247–930 m depth.

Actinostola georgiana is an Antarctic endemic from bathyal depths ( Fig. 27a ).

Genus Hormosoma Stephenson, 1918a

Figures

FIGURE 25. External anatomy of Actinostola georgiana Carlgren, 1927. a) Lateral view of living specimen [AMNH-4766]. b) Lateral view of preserved specimen [AMNH-4766]. c) oral view of preserved and contracted specimen [AMNH-4792]. d) Oral view of preserved specimen [AMNH-4766]. Scale bars: a, 10 cm; b, d, 40 mm; c, 50 mm.

FIGURE 26. Cnidae of Actinostola georgiana Carlgren, 1927. a, c, e, h) Basitrichs. b, f, i–k) Microbasic p-mastigophores. d) Spirocyst. g) Microbasic b-mastigophore.

FIGURE 27. Distribution map of species. a) Actinostola georgiana Carlgren, 1927. b) Hormosoma scotti Stephenson, 1918. c) Stomphia selaginella (Stephenson, 1918). d) Galatheanthemum profundale Carlgren, 1956. e) Actinoscyphia plebeia (McMurrich, 1893). f) Eltaninactis infundibulum Dunn, 1983. Green triangles, type locality; green circles, previous localities; red circles, localities from this study; dark line, Subtropical Front; light line, Polar Front.