Andvakia manoloi Lauretta, 2013, sp. nov.

Andvakia manoloi sp. nov.

(Figures 2, 3 & 4)

Type material. Holotype: MACN-IN 39033; Punta Colorada, Río Negro, Argentina (41º 46' S, 65º 00' W), November 2010, intertidal zone. Col. Daniel Lauretta. Paratype: Invertebrate collection of MLP 3725, one specimen. Collecting data same as those of holotype. Other material examined: MACN-IN 39034, two specimens. Collecting data same as those of holotype.

Description:

External anatomy. Flat base attached to substratum (rounded in one specimen), to 9 mm diameter. Column longer than wide, 19 mm long and 10 mm wide in preserved holotype; mean of all observed specimens in preservation 19.3 mm long and 10.5 mm wide. Column divisible into physa, scapus, scapulus and capitulum (Fig. 2, 3 a). Cuticle covers scapus and scapulus (Fig. 2, 3 a, 3b). Scapus brown, with tenaculi to which sand and gravel attach (Fig. 2). Scapulus lighter brown, without tenaculi or attached particles. Capitulum white, without tenaculi (Fig. 2, 3 a). When contracted, capitulum and scapulus covered by scapus.

Tentacles very fragile, white (preserved specimens), most inverted in preservation, very difficult to count, 36 (but probably 48 according to number of mesenteries), small to 1.5 mm, inner longer than outer.

Internal anatomy. Twenty four pairs of mesenteries (48 mesenteries) in three cycles plus fourth incomplete cycle (6+6+12+24?=48). First cycle perfect (two specimens had only five pairs perfect). At actinopharynx, only mesenteries of second cycle with filaments (Fig. 3 e). Two pairs directives, one attached to more or less differentiated siphonoglyph, second attached to smooth part of actinopharynx. At least a few more mesenteries proximally than distally (Fig. 3 c). Retractor muscles strong, restricted (Fig. 3 e). Second cycle and additional mesenteries without retractors. Parietal muscles strong, asymmetrical (Fig. 3 d), present only on mesenteries of first cycle. Marginal sphincter muscle mesogloeal, strong, reticulate, occupying entire width of mesogloea in upper part of scapulus and lower half of capitulum (Fig. 3 a). Longitudinal muscles of tentacles and radial muscles of oral disc ectodermal. Acontia short, poorly coiled, white, on mesenteries of first, second, and third cycle. Basilar muscles absent (Fig. 4).

Cnidom and cnidae distribution.

Spirocysts, basitrichs, microbasic p -mastigophores and microbasic p -amastigophores (Fig. 5). See Table 1 for distribution and size. Despite making several preparations from tentacles of both specimens, I found no cnidocysts, probably because the epidermis was detached, so data for cnidae of tentacles are from a third specimen.

M p -mastigophores (28.1–32.4) x (3.0–3.7) 29.7 ± 2.3 x 3.5 ± 0.4 3 1/2

...... continued on the next page Distribution and natural history. Members of Andvakia manoloi sp. nov. are inconspicuous inhabitants of the upper intertidal zone of the rocky intertidal zone of Punta Colorada. The beach has a strong wave action and semidiurnal tidal regime with an average tide amplitude of 6.01 meters (Servicio de Hidrografia Naval).The nine specimens were found together more or less strongly attached to the rocky wall of a small cave covered by the mussel Perumytilus purpuratus (Lamark) and sand, protected from the wave action. During low tide, the specimens remained exposed to the air, but always away from sunlight and sight, so the specimens were discovered by touch. The record of Andvakia manoloi sp. nov. in Argentinean waters represents the first record of the genus Andvakia for the South Atlantic Ocean and the southernmost record worldwide.

Despite searching since 2007 in both the intertidal and subtidal zone of the patagonic coast from Rio Negro province to Tierra del Fuego province, this was the first and only time that I found this species. The species probably has a broader distribution, but since it is small and looks very similar to the substrata, it is very difficult to locate. It may also occur subtidally. No similar specimens were found in the MACN or MLP collections.

There are no other species belonging to genus Andvakia in Argentinean waters, but A. manoloi sp. nov. is not the only sea anemone from Argentina with the column covered by cuticle. Phellia exlex (McMurrich, 1904) has been recorded from Argentina from 100 m to 400 m deep off Buenos Aires Province (Riemann-Zürneck 1975; Zamponi & Acuña 1991), I compared the specimens found with specimens of P. exlex. Andvakia and Phellia Gosse, 1858 differ in the presence of basilar muscles (Daly & Goodwill 2009: 272). Despite the similarities between both species, P. exlex has well developed basilar muscles, so there is no doubt that the specimens found in Punta Colorada cannot be assigned to P. e x l e x.

Etymology. The species is named after Manuel Gallinar Marcos (Manolo), in appreciation for all the time and wisdom he has shared with me.

Differential diagnosis of Andvakia manoloi sp. nov. Forty eight tentacles. Six pairs of perfect mesenteries. More mesenteries in proximal part than in distal part of the column. Mesogloeal sphincter strong, reticulated. Retractor muscles of the mesenteries restricted, parietal muscle asymmetrical, strong. Column divided into scapus, scapulus and capitulum.