Dactylanthus antarcticus ( Clubb, 1908 )

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 : 40-44

Dactylanthus antarcticus ( Clubb, 1908)

( Figs. 14 , 21–22 ; Table 9; Appx. 1, 2)

Cystiactis antarctica Clubb, 1908 .

Dactylanthus antarcticus: Carlgren 1911 ; Stephenson 1918a; Pax 1923; Carlgren 1940; Carlgren 1949; Dunn 1983; England & Robson 1984; Dayton et al. 1997; Riemann-Zürneck 1990; Cappola & Fautin 2000.

MATERIAL EXAMINED

Polarstern ANT XVII/3 : stn. PS56/159-1 (AMNH-4526, 1 specimen) .

Polarstern ANT XIX/3 : stn. PS61/48-1 ( BEIM: ANT-4089, 1 specimen) .

Polarstern ANT XIX/5 : stn. PS61/182-1 ( BEIM: ANT-4657, 1 specimen) .

TABLE 8. Size ranges of the cnidae of Liponema multiporum Hertwig, 1882 ; for comparative cnidae data of the pecies see Dunn (1983). 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 (Χ) and standard deviation ( SD) no calculated because are based on fewer then 40 capsules.

TABLE 9. Size ranges of the cnidae of Dactylanthus antarcticus ( Clubb, 1908) ; for comparative cnidae data of the species see 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 in fewer than 40 capsules.

(1) Named as heterotrichs by England and Robson (1994).

DIAGNOSIS

Pedal disc well developed, flat, to 35 mm diameter. Column delicate, not differentiated into regions, elongated or more or less ovoid, to 47 mm diameter and 45 mm height in preserved specimens. Living and preserved specimens whitish to yellowish. Column with 24 longitudinal rows of tentaculate vesicles in endo-and exo-coels, about ten vesicles per row. Mesenterial insertions visible. Column beige with irregular orange spots in living specimens, tentacles whitish; preserved specimens pink to tan. Tentacles digiform, to 24; short (to 6 mm) and long (to 9 mm) tentacles alternate. Marginal sphincter muscle absent. Mesenteries delicate, to 12 pairs, arranged in two cycles, only first cycle perfect but both fertile. Mesenteries fused at different levels; mesenterial filaments without ciliated tracts. Retractor muscles weak, diffuse, double; parietobasilar muscles not developed. Cnidom: Spirocysts and holotrichs. For a complete description of Dactylanthus antarcticus , see Dunn (1983) and Cappola and Fautin (2000).

GEOGRAPHIC AND BATHYMETRIC DISTRIBUTION

Dactylanthus antarcticus is distributed in the Antarctic (Ross Sea, Drake Passage, and Antarctic Peninsula) and in the sub-Antarctic region (Tierra de Fuego [ Argentina] and Chilean fiords), between 37–610 m depth ( Dunn 1983; Dayton et al. 1997).

The material from this study confirms the geographic distribution of the species in Antarctic Peninsula, and represents the first record for the species in South Georgia, between 214–343 m depth. Although specimens were not collected, the presence of the species in the eastern Weddell Sea is here cited for the first time based on an underwater photography survey (Rodríguez unpubl. data); the species was identified in eight stations, between 66–366 m depth (see Appx. 2).

Dactylanthus antarcticus is a circumpolar Antarctic and sub-Antarctic species, from continental shelf and bathyal depths ( Fig. 14e ).

REMARKS

Molecular studies showed that Dactylanthus antarcticus belongs within endomyarian actiniarians (Daly et al. 2008, Rodríguez and Daly 2010; Rodríguez et al. 2012) and does not deserve the taxonomic rank of suborder ( Ptychodacteae ) as established by Cappola and Fautin (2000); thus we included it within Endomyaria.

MESOMYARIA Stephenson, 1921

Family ACTINOSTOLIDAE Carlgren, 1893

Genus Actinostola Verrill, 1883

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 21. External anatomy of Dactylanthus antarcticus (Clubb, 1908) a) Oral view of living specimen [AMNH-4526]. b) Oral-lateral view of preserved specimen [AMNH-4526]. c–d) lateral view and base of preserved specimen [BEIM(ANT- 4089)]. Scale bars: a, 45 mm; b, 30 mm; c–d, 35 mm.

FIGURE 22. Cnidae of Dactylanthus antarcticus (Clubb, 1908). a, c, d, f–i) Holotrichs. b, e) Spirocyst.