Bolocera kerguelensis Studer, 1879

Gusmão, Luciana C. & Rodríguez, Estefanía, 2021, Deep-Sea Anemones (Cnidaria: Anthozoa: Actiniaria) From The South Atlantic, Bulletin of the American Museum of Natural History 2021 (444), pp. 1-73 : 18-21

Bolocera kerguelensis Studer, 1879

Figures 7–8, table

MATERIAL: MNRJ 8175 (1 specimen) ; locality: Ak. Ioffe Cruise 29, Shirshov st. 2184–5, Superestação 1, Sta. 201, series #1030, Mid-Atlantic Ridge, 29°27.12′ S 10°08.72′ W, collected on 20 November 2009 by MAR-ECO #36066 (4120 m). MNRJ 8181 (1 specimen) ; locality: Ak. Ioffe Cruise 29, Shirshov st. 2184–5, Superestação 7, Sta. 201, series #1030, Mid-Atlantic Ridge, 29°27.12′ S 10°08.72′ W, collected on 20 November 2009 by MAR-ECO #36038 (4120 m) .

MATERIAL EXAMINED: Bolocera kerguelensis: AMNH 4653 (5 specimens) ; locality: ANT XIX/5 Cruise , LAMPOS Program , RV Polastern , Sta. 61/150, Burdwood / Namuncurá Bank, 54°30.22′ S 56°08.20′ W, collected on 6 April 2002 by E. Rodríguez (286 m). AMNH 4912 (1 specimen) ; locality: ANT XXI/2 Cruise , BENDEX Program , RV Polastern, Sta. PS 65/109- 1, Antarctica, North Kapp Norvegia, 70°47.88′ S 11°21.56′ W, collected on 10 December 2003 by E. Rodríguez (1488 m) .

EXTERNAL ANATOMY (fig. 7): Pedal disc well developed, circular, with well-marked limbus, 49–62 mm in diameter in preserved specimens. Column funnel shaped, short, cylindrical, smooth, not divided into regions, much wider than pedal disc; margin not tentaculate. Column beige, 45–49 mm in diameter and 35–44 mm in length in preserved specimens. Oral disc circular, wide, nonretractile, same color as column, with large central mouth with two visible siphonoglyphs; specimens with everted actinopharynx due to sampling process (fig. 7D); 44–62 mm in diameter in preserved specimens. Tentacles deciduous with basal marginal endodermal sphincter, numerous, smooth, thick, with longitudinal ridges, 170–182 in 6 cycles (6+6+12+24+48+n) in most of oral disc (fig. 7D); many tentacles autotomized and detached from oral disc of preserved specimens, their absence marked by holes in oral disc (fig. 7D). Inner and outer tentacles of similar or dissimilar size due to regeneration (fig. 7D); longest tentacle up to 50 mm in preserved specimens.

INTERNAL ANATOMY AND HISTOLOGY (fig. 7): Body wall thickness uniform throughout column: gastrodermis (316–537 μm), mesoglea (314–595 μm), and epidermis (287–542 μm) (fig. 7B). Marginal sphincter endodermal musculature diffuse (fig. 7C). Longitudinal musculature of tentacles ectodermal.

Mesenteries in five cycles (6+6+12+24+n = 90–93) spanning most of body length (fig. 7E, F): mesenteries of first and second cycles perfect, fertile, except for two pairs of sterile directives (fig. 7E); each pair of directives associated with one siphonoglyph; third cycle mostly imperfect, sometimes perfect, fertile (fig. 7F, G); fourth and fifth cycles imperfect (fig. 7G, H and fig. 7G, I, J, respectively). Mesenteries of first to fourth cycles with filaments (fig. 7F, G); those of fifth cycle without filaments (fig. 7F, H). Same number of mesenteries distally and proximally. All specimens collected in November males; major axis of spermatic cysts 113–405 μm (fig. 7G, H). Species inferred gonochoric. Retractors of all mesenteries strong, diffuse (fig. 7F–H, I); parietobasilar musculature in all mesenteries (fig. 7F–L), but particularly strong and well developed with free mesogleal flap in mesenteries of first to fourth cycles (fig. 7F, G, K); mesenteries of fifth cycle with weak parietobasilar musculature (fig. 7K).

CNIDOM (fig. 8): Spirocysts, basitrichs, b -mastigophores, p -mastigophores A. See figure 8 and table 3 for size and distribution.

DISTRIBUTION AND NATURAL HISTORY: The two specimens of Bolocera kerguelensis were collected in the area west of the Mid-Atlantic Ridge in the South Atlantic at 4120 m. The specimens were not attached to any solid substrate, which suggests they might rest loosely on the sediment as noted by other authors ( Dunn and Bakus, 1977; Riemann-Zürneck, 1979). Our new records extend the geographic range of the species—which is widespread in the Southern Ocean (plus doubtful records in the South African coast: see Rodríguez and López-González, 2013) and on both sides of South America ( Dunn, 1983; Riemann-Zürneck, 1986; Rodríguez and López-González, 2013)—to include the area surrounding the SMAR region above the 35° S parallel (fig. 1). The closest previous record to the Mid-Atlantic Ridge is from the area around the Traversay Islands ( Dunn, 1983) but at a much shallower depth (1532–1590 m). We also extend slightly the bathymetric range of this eurybathic species known from the continental shelf to bathyal depths in the Antarctic and sub-Antarctic regions ( Rodríguez et al., 2007; Rodríguez and López-González, 2013) from 45–3947 m to 45–4120 m. These new records represent a third instance of a deep-sea anemone found in Antarctica and sub-Antarc- cnidae of specimens examined in this study tica whose geographic range extends beyond agrees with the cnidom given by Rodríguez and the Southern Ocean, the others being Galathe- López-González (2013) for B. kerguelensis from anthemum profundale Carlgren, 1956, and Lipo- Antarctica, except for our finding of p - mastigonema multiporum Hertwig, 1882 (see Rodríguez phores A in the column (fig. 8C) and nemato- et al., 2007). cysts we identified as b -mastigophores in the REMARKS: The differentiation of species in the filament of our specimens (fig. 8L), both of genus Bolocera based on morphology or cnidae which have never been described in B. kerguelis difficult, particularly for species recorded for ensis. It is possible these two nematocysts were the South Atlantic (Rodríguez and López- not found in previous studies due to their scar- González, 2013). The circumscription of the city, particularly of the p -mastigophores A of the genus Bolocera in the South Atlantic and Antarc- column, but their presence has been confirmed tic region has varied from two species—either B. in histological sections. The b -mastigophores kerguelensis and B. tuediae occidua (Riemann- found in the filaments are similar to those found Zürneck, 1980) or B. kerguelensis and B. pauci- in other actiniids (e.g., Epiactis Verrill, 1869a , cornis Dunn, 1983 —to only one, B. tuediae Glyphoperidium Roule, 1909 , Isosicyonis Carlkerguelensis ( Riemann-Zürneck, 1986). However, gren, 1927).

because Rodríguez and López-González (2013)

found inconsistencies in the morphological and

Genus Isotealia Carlgren, 1899

cnidae characters used by Riemann-Zürneck

(1980) and Dunn (1983) to differentiate Bolocera DIAGNOSIS (modified from Carlgren, 1949; species in the Southern Ocean, the authors syn- modifications in bold): Actiniidae with wellonymized all species under B. kerguelensis until developed pedal disc. Column smooth, divisible further studies (Rodríguez and López-González, into scapus and scapulus. Scapus with easily 2013). For this reason, until a thorough morpho- deciduous cuticle. Margin with perforated logical and molecular revision of the genus is pseudoacrorhagi with basitrichs. Endodermal carried out, we identify our specimens as B. ker- marginal sphincter well developed, circumguelensis as the morphology of our specimens scribed. Tentacles short, hexamerously arranged, generally agree with previous descriptions of that inner longer than outer ones. Two siphospecies (e.g., Riemann-Zürneck, 1980; Rodríguez noglyphs. Approximately same number of mes- and López-González, 2013). One exception is the enteries proximally and distally. Retractors fertility of the mesenteries of the fourth cycle, strong, diffuse. Parietobasilar and basilar muswhich was previously described as sterile (Rodrí- culature distinct. Mesenteries of first and secguez and López-González, 2013), but they were ond cycle sterile. Cnidom: spirocysts, basitrichs, fertile in our specimens (fig. 7F, G). Similarly, the p -mastigophores A.