Epiactis 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 : 18-23

Epiactis georgiana Carlgren, 1927

( Figs. 3 , 8–9 ; Table 4; Appx. 1, 2)

Epiactis georgiana: Carlgren, 1927 ; Carlgren 1949; Carlgren 1959; Dunn 1983.

Epiactis crateriformis Carlgren & Stephenson, 1929 ; Carlgren 1949.

Epiactis adeliana Carlgren & Stephenson, 1929 ; Carlgren 1949.

? Epiactis brucei Carlgren, 1939 ; Carlgren 1949.

MATERIAL EXAMINED

Polarstern ANT XV/3: stn. PS48/050 ( BEIM: ANT-4272, 1 specimen) ; stn. PS48/062 ( BEIM: ANT-4373, 4 specimens) ; stn. PS48/071 ( BEIM: ANT-4277, 2 specimens; BEIM: ANT-4987, 1 specimen) ; stn. PS48/077 ( BEIM: ANT-4375, 3 specimens; BEIM: ANT-4400, 1 specimen) ; stn. PS48/082 ( BEIM: ANT-4372, 3 specimens) ; stn. PS48/084 ( BEIM: ANT-4274, 1 specimen) ; stn. PS48/095 ( BEIM: ANT-4240, 2 specimens) ; stn. PS48/189 ( BEIM: ANT-4266, 1 specimen; BEIM: ANT-4279, 2 specimens) ; stn. PS48/197 ( BEIM: ANT-4294, 2 specimens) ; stn. PS48/222 ( BEIM: ANT-4367, 5 specimens) ; stn. PS48/336 ( BEIM: ANT-4276, 2 specimens; AMNH-4286, 6 specimens; BEIM: ANT-4406, 2 specimens; AMNH-4407, 2 specimens; BEIM: ANT-4408, 2 specimens; BEIM: ANT-4409, 2 specimens; BEIM: ANT-4413, 1 specimen; BEIM: ANT-4414, 1 specimen; BEIM: ANT-4415, 1 specimen; BEIM: ANT-4416, 1 specimen; BEIM: ANT-4417, 1 specimen; BEIM: ANT-4418, 1 specimen; BEIM: ANT-4419, 2 specimens; BEIM: ANT-4420, 1 specimen; BEIM: ANT-4421, 1 specimen; BEIM: ANT-4422, 2 specimens; BEIM: ANT-4423, 1 specimen; BEIM: ANT-4424, 1 specimen; BEIM: ANT- 4425, 1 specimen; BEIM: ANT-4426, 1 specimen; BEIM: ANT-4427, 1 specimen) ; stn. PS48/338 ( BEIM: ANT- 4229, 1 specimen; BEIM: ANT-4237, 2 specimens) .

Polarstern ANT XVII/3 : stn. PS56/65-1 ( BEIM: ANT-4485, 4 specimens; BEIM: ANT-4486, 2 specimens); stn. PS56/85-1 ( BEIM: ANT-4481, 2 specimens; BEIM: ANT-4559, 1 specimen); stn. PS56/102 ( BEIM: ANT- 4489, 1 specimen; BEIM: ANT-4493, 1 specimen; BEIM: ANT-4495, 1 specimen; BEIM: ANT-4552, 2 specimens); stn. PS56/119-1 ( BEIM: ANT-4494, 1 specimen) ; stn. PS56/166-1 ( BEIM: ANT-4458, 2 specimens) .

Polarstern ANT XIX/3 : stn. PS61/048-1 (AMNH-4124, 6 specimens) ; stn. PS61/052-1 (AMNH-4121, 10 specimens); stn. PS61/060-1 (AMNH-4085, 3 specimens); stn. PS61/061-1 (AMNH-4116, 1 specimen; AMNH- 4132, 1 specimen); stn. PS61/062-1 ( BEIM: ANT-4115, 4 specimens) ; stn. PS61/063-1 (AMNH-4073, 2 specimens); stn. PS61/064-1 (AMNH-4001, 19 specimens; BEIM: ANT-4728, 1 specimen; BEIM: ANT-4729, 1 specimen; BEIM: ANT-4742, 12 specimens; AMNH-4743, 13 specimens; BEIM: ANT-4744, 12 specimens; BEIM: ANT-4745, 12 specimens; BEIM: ANT-4746, 12 specimens; BEIM: ANT-4748, 12 specimens; AMNH- 4749, 12 specimens; AMNH-4750, 10 specimens; BEIM: ANT-4751, 10 specimens; BEIM: ANT-4752, 12 specimens; AMNH-4753, 10 specimens; BEIM: ANT-4754, 14 specimens; BEIM: ANT-4755, 12 specimens; AMNH-4756, 12 specimens; AMNH-4757, 10 specimens; BEIM: ANT-4758, 12 specimens; BEIM: ANT-4759, 8 specimens; BEIM: ANT-4760, 1 specimen); stn. PS61/065-1 (AMNH-4161, 5 specimens) ; stn. PS61/068-1

( BEIM: ANT-4118, 5 specimens; BEIM: ANT-4164, 9 specimens); stn. PS61/069-1 ( BEIM: ANT-4088, 2 specimens) ; stn. PS61/070-1 ( AMNH -4055, 1 specimen; AMNH -4130, 1 specimen); stn. PS61/071-1 (AMNH- 4063, 1 specimen) ; stn. PS61/093-1 (AMNH-4069, 1 specimen).

Polarstern ANT XIX/5 : stn. PS61/253 ( BEIM: ANT-4665, 1 specimen; BEIM: ANT-4679, 1 specimen; AMNH-4691, 1 specimen; AMNH-4692, 1 specimen) .

Polarstern ANT XXI/2 : stn. PS65/121-1 (AMNH-4918, 1 specimen) ; stn. PS65/132-1 (AMNH-4916, 2 specimens); stn. PS65-166-1 (AMNH-4932, 1 specimen); stn. PS65/174-1 (AMNH-4838, 5 specimens; AMNH- 4890, 1 specimen); stn. PS65/245-1 (AMNH-4868, 4 specimens); stn. PS65/248-1 (AMNH-4855, 4 specimens; AMNH-4882, 3 specimens); stn. PS65/265-1 (AMNH-4849, 6 specimens; BEIM: ANT-4883, 4 specimens); stn. PS65/274-1 (AMNH-4825, 3 specimens) ; stn. PS65/276-1 (AMNH-4841, 18 specimens; AMNH-4842, 6 specimens; AMNH-4872, 3 specimens); stn. PS65/280-1 (AMNH-4850, 7 specimens); stn. PS65/292-1 (AMNH- 4896, 1 specimen).

COMPARATIVE MATERIAL EXAMINED

Epiactis georgiana Carlgren, 1927 . SMNH-type-4870. Syntypes. “Leg. Swedish South Polar Exp. 1901–1903. st. 30, 54º24’S 36º26’W, 26/5, 1902, depth 125 m, South Georgia, Moränenfjord mud with some stones”. (2 specimens).

DIAGNOSIS

Flat, well developed pedal disc, to 57 mm diameter. Column smooth, cylindrical, to 58 mm diameter and 76 mm height, divided into scapus and capitulum, with parapet and fosse well developed. Living specimens whitish to light orange in colour, preserved specimens tan to yellowish. Mesenterial insertions visible. Juveniles attached to distal column, which often folds into a marginal collar. Tentacles tough, to 96. Marginal sphincter muscle endodermal, circumscribed. More mesenteries proximally than distally. Mesenteries to 54 pairs, arranged in 5 cycles, all perfect and fertile except youngest cycles. Retractor muscles strong, diffuse, parietobasilar muscles well developed with free mesogleal pennon. Cnidom: Spirocysts, basitrichs, and microbasic p -mastigophores. For a complete description of Epiactis georgiana , see Dunn (1983).

GEOGRAPHIC AND BATHYMETRIC DISTRIBUTION

Epiactis georgiana occurs between 50–935 m depth, in the Ross Sea and Adélie Land (close to the Ross Sea, specimens cited as E. crateriformis ), and in the other side of Antarctica, in the Scotia and Weddell seas ( Carlgren & Stephenson 1929; Dunn 1983). Epiactis georgiana is also cited from the Chilean coast ( Carlgren 1959); this record represents the most northern (41ºS) and shallowest record, but is based in a sole, poorly preserved specimen. In light of the synonymy of E. brucei with E. georgiana —see remarks—the depth range of the species is 50– 2,580 m ( Carlgren 1939).

Excoffon & Acuña (1995) extended the geographic distribution of Epiactis georgiana to Argentina (38º10’S 57º12’W). According to Riemann-Zürneck (1986a) this species has a disjunt distribution along the cold waters of the Argentinean coast. This unusual distribution is also cited for Isosicyonis alba Studer, 1879 and other benthic cnidarians ( Riemann-Zürneck 1973, 1980, 1986a, 1991) and it is caused by the hydrographic features of the southeastern Atlantic (see Zenk 1981; Riemann-Zürneck 1991; Häussermann & Försterra 2005).

The specimens examined in this study are mainly from the eastern Weddell Sea, Drake Passage, and Elephant Island, between 118– 1,227 m depth; however, this species is most abundant at about 400–500 m depth.

Epiactis georgiana is considered an Antarctic and sub-Antarctic circumpolar species from continental shelf and bathyal depths ( Fig. 3e ).

REMARKS

Epiactis adeliana is considered different from E. crateriformis (synonymy of E. georgiana ) by some authors ( Carlgren & Stephenson 1929; Dunn 1983) based on the hexamerous arrangement of the mesenteries in E. adeliana , the form of the parietobasilar muscles, and differences in the cnidae. However, the original description of E. adeliana is based in a sole specimen ( Carlgren & Stephenson 1929). After examining hundreds of specimens, we found that the morphology of the parietobasilar muscles changes proximally and distally within a single specimen and thus we do not consider this feature enough to distinguish species in this genus. The cnida data from E. adeliana corresponds with that of E. georgiana ( Carlgren & Stephenson 1929 and Table 4). Furthermore, E. adeliana and E. crateriformis are sympatric and thus there is no geographical reason to distinguish both species.

TABLE 4. Size ranges of the cnidae of Epiactis georgiana Carlgren, 1927 ; for comparative cnidae data of the species see Carlgren (1927, 1939), Carlgren and Stephenson (1929), and Dunn (1983). 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 on fewer than 40 capsules.

(1) Named as basitrichs by Dunn (1983).

Carlgren (1939) distinguished Epiactis brucei from the other species of Epiactis in the marginal sphincter muscle and cnidae: the marginal sphincter muscle is strong and circumscribed with a relative thick main mesogleal lamella in E. brucei ; the basitrichs in the scapus are larger and the microbasic p -mastigophores in the actinopharynx are shorter in E. brucei than in other species of Epiactis . The type locality of E. brucei is located in the Weddell Sea (71º22’S 16º34’W, 2,580 m, off Kapp Norvegia) from where most of the material of this study comes. The slight differences in cnidae and marginal sphincter muscle morphology are attributable to the intraspecific variability and thus we consider E. brucei a synonymy of E. georgiana .

Genus Glyphoperidium Roule, 1909

Figures

FIGURE 3. Distribution map of species. a) Overview. b) Actinernus antarcticus (Carlgren, 1914). c) Aulactinia sulcata (Clubb, 1902). d) Bolocera kerguelensis Studer, 1879. e) Epiactis georgiana Carlgren, 1927. f) Glyphoperidium bursa Roule, 1909. Green triangles, type locality; green circles, previous localities; red circles, localities from this study; dark line, Subtropical Front; light line, Polar Front. AP, Antarctic Peninsula; DP, Drake Passage; RS, Ross Sea; SS, Scotia Sea; WD, Weddell Sea.

FIGURE 8. External anatomy of Epiactis georgiana Carlgren, 1927. a) Lateral view of living specimen brooding juveniles on margin of the column [BEIM(ANT-4489)]. b) Oral view of preserved specimen with free embryos (yellowish dots) in the coelenteron visible through the expanded oral disc [AMNH-4882]. c) Oral view of semi-contracted specimen [AMNH-4868)]. d–e) Lateral view of preserved specimen [AMNH-4868], [AMNH-4286)]. Scale bars: a, d, 20 mm; b, 10 mm; c, 15 mm; e 30 mm.

FIGURE 9. Cnidae of Epiactis georgiana Carlgren, 1927. a, c, g) Spirocysts. b, d, f, h, i, k, l, n) Basitrichs. e, m, o, p) Microbasic p-mastigophores. j, q) Microbasic b-mastigophores.