Corallimorphus rigidus Moseley, 1877

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 : 87-91

Corallimorphus rigidus Moseley, 1877

( Figs. 41 , 48–49 ; Table 18; Appx. 1, 2)

Corallimorphus rigidus Moseley, 1877 ; Hertwig 1882a, b; Andres 1883; Hertwig 1888; Carlgren 1899; Stephenson 1920b;

Stephenson 1922; Carlgren 1928; Carlgren & Stephenson 1929; Carlgren 1943; Carlgren 1949; Fautin 1984; Fautin et al.

2002; Hartog & Grebelny 2003; Fautin 2011b. Corallimorphus obtectus Hertwig, 1888 ; Stephenson 1920b; Stephenson 1922; Carlgren & Stephenson 1929; Carlgren 1949. Corynactis sp. : Hertwig 1888. Isocorallion Hertwigi Carlgren, 1900 . Isocorallion hertwigi: Stephenson 1922 . Chalmersia sp. : Delage & Hérouard 1901.

MATERIAL EXAMINED

Polarstern ANT XXII/3 : stn. PS67/059–10 ( BEIM: ANT-3434, 1 specimen) .

ADDITIONAL MATERIAL EXAMINED

Corallimorphus rigidus Moseley, 1877 . BEIM: ANT-4739. RV Sonne SO 156/3, stn. 7166–6, 36º48.48’S 73º78.42W, 25/04/2001, AGT, 1,300 m. (1 specimen).

DIAGNOSIS

Pedal disc well developed without basilar muscles. Column cylindrical, shorter than diameter of discs (to 13 mm); column hyaline but cartilaginous and rigid in consistency, with mesenterial insertions visible. Sparse tan epidermis may be attached to column; brown epidermis may persist near base of tentacles; oral disc wider than pedal disc, with raised lips around slit mouth. Relatively short, capitate tentacles. Marginal tentacles to 48, 24 relatively short (1.3 mm in length) in exocoels, 12 communicating with primary and secondary endocoels (6.1 mm in length) and 12 with tertiary endocoels (2.4 mm in length). Marginal and discal tentacles in approximately 2:1 marginal:discal ratio. Discal tentacles to 24 (26); six communicating with primary endocoels near the month, six with primary endocoels near the margin, and 12 with tertiary endocoels near the margin. No marginal sphincter muscle. Mesenteries thin, to 24 pairs, arranged in three cycles, first and second cycles perfect. Retractor muscles diffuse. Cnidom: Spirocysts, holotrichs, basitrichs, and microbasic b - and p -mastigophores. For a detailed description of Corallimorphus rigidus , see Hertwig (1882a, b) and Fautin (1984).

GEOGRAPHIC AND BATHYMETRIC DISTRIBUTION

Corallimorphus rigidus has been cited in Indian and Pacific sub-Antarctic waters, between 274– 4,429 m depth ( Fautin 1984, 2011b) but also in the northern hemisphere (see Fautin 2011a, b for complete distribution of the species).

The only specimen of Corallimorphus rigidus in this study was collected in the Weddell Sea (67º30.37'S 00º03.74'W), between 4,646–4,648 m depth. This new record represents the most southern record for the species, and the first record in the Antarctic region (south of the Polar Front) and in the Atlantic side .

Corallimorphus rigidus is a deep-sea species in the Antarctic and sub-Antarctic regions, inhabiting continental shelf and abyssal depths (see Fig. 41e , only southern hemisphere localities represented).

TABLE 18. Size ranges of the cnidae of Corallimorphus profundus Moseley, 1877 and C. rigidus Moseley, 1877 ; for comparative cnidae data of the species see Fautin (1984) and Riemann-Zürneck and Iken (2003). 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 hoplotelic Mc. p -mastigophores by Fautin (1984). (2) Named as lanceolate basitrichs by Riemann-Zürneck and Iken (2003). REMARKS

The additional material of Corallimorphus rigidus examined in this study (from Chile) was larger than the Antarctic specimen we examined; this additional specimen presented larger numbers of mesenteries and tentacles (48 mesenteries, 96 marginal and 48 discal tentacles) corresponding to the larger size of the specimen (column 80 mm in diameter).

We found three valid species of Corallimorphus in the Antarctic and sub-Antarctic regions: C. profundus , C. rigidus , and C. niwa Fautin, 2011b . The three species can be distinguished in external morphology and consistency of the column. Although the differences are in population-level trends rather than in absolute differences between any two specimens, these three species also differ in the ratio of marginal:discal tentacles: approximately 1: 1 in C. niwa , 2: 1 in C. rigidus , and usually higher, 2–6:1, in C. profundus .

Figures

FIGURE 41. Distribution map of species. a) Actinauge verrillii McMurrich, 1893. b) Hormathia armata Rodríguez & López- González, 2001. c) Hormathia lacunifera (Stephenson, 1918). d) Corallimorphus profundus Moseley, 1877. e) Corallimorphus rigidus Moseley, 1877. Green triangles, type locality; green circles, previous localities; red circles, localities from this study; dark line, Subtropical Front; light line, Polar Front.

FIGURE 48. External anatomy of Corallimorphus rigidus Moseley, 1877. a) Oral view of preserved specimen [BEIM(ANT- 3434)]. b) View of the pedal disc of preserved specimen [BEIM(ANT-3434)]. c) Oral view of preserved specimen [BEIM(ANT-4739)]. d) Lateral view showing the pedal disc of specimen preserved [BEIM(ANT-4739)]. Scale bars: a–b, 15 mm; c, 40 mm; d, 50 mm.

FIGURE 49. Cnidae of Corallimorphus rigidus Moseley, 1877. a, d, h, k) Microbasic p-mastigophores. b, e, g, l) Microbasic b- mastigophores. c, i, j, m) Holotrichs. f) Spirocyst. Note h is at different scale.