Anemonia sargassensis Hargitt, 1908

Gonzalez-Munoz, Ricardo, Simoes, Nuno, Tello-Musi, Jose Luis & Rodriguez, Estefania, 2013, Sea anemones (Cnidaria, Anthozoa, Actiniaria) from coral reefs in the southern Gulf of Mexico, ZooKeys 341, pp. 77-106 : 80-81

Anemonia sargassensis Hargitt, 1908 Figure 3, Table 2

Anemonia sargassensis Hargitt 1908: 117-118.

Anemonia antillensis Pax 1924: 94, 99-100, 119.

Anemonia sargassiensis [sic]: Carlgren 1949: 50.

Material examined.

Alacranes reef (22°31'35"N, 89°46'05"W; two specimens), Cayo Arenas reef (22°07'05"N, 91°24'17"W; three specimens), La Gallega reef (19°13'20"N, 96°07'39"W; two specimens), Ingenieros reef (19°08'41"N, 96°05'22"W; two specimens).

Diagnosis.

Fully expanded oral disc and tentacles 9-50 mm in diameter. Oral disc smooth, 4-22 mm in diameter, wider than column, dark-orange, brownish, greenish or dark-red, with white or yellowish endocoelic radial stripes tapering from tentacle bases (Figure 3A, B); mouth bright orange or pink (Figure 3B). Tentacles hexamerously arranged in 4-5 cycles (48-76 in number), moderately long (to 6-19 mm length), smooth, slender, tapering distally, inner ones longer than outer ones, contractile, dark-orange to reddish, sometimes with whitish or yellowish tips and pink or purple flashes (Figure 3 A–C). Fossa well marked (Figure 3G). Poorly marked endocoelic marginal projections, 17-35, forming acrorhagi (Figure 3G), with holotrichs and basitrichs. Column cylindrical, short, smooth, 5-11 mm in diameter and 5-12 mm in height, dark-orange to dark-red. Pedal disc well-developed, 6-16 mm in diameter, wider than column (Figure 3C), bright-orange or pink. Mesenteries irregularly arranged in four cycles: first and second cycles perfect, others imperfect; more mesenteries proximally than distally (82-89 and 44-48 pairs respectively in specimens examined). Directives absent, 5-6 siphonoglyphs in specimens examined (Figure 3D, E). Gametogenic tissue not observed in specimens examined. Larvae observed in coelenteron of one specimen examined (Figure 3E). Retractor muscles diffuse to restricted; parietobasilar muscles weak with short mesogleal pennon (Figure 3F). Basilar muscles well-developed (Figure 3H). Marginal sphincter muscle endodermal, diffuse (Figure 3G). Longitudinal muscles of tentacles ectodermal (Figure 3I). Zooxanthellae present. Cnidom: basitrichs, holotrichs, microbasic b- and p-mastigophores and spirocysts (Figure 3 J–U; see Table 2).

Natural history.

Anemonia sargassensis inhabits shallow waters of the lagoon reef zone, often above Thalassia testudinum blades, but is also found under stones and coral gravel, between 0.5-2 m. It is often reported on floating Sargassum ( Carlgren and Hedgpeth 1952). Asexual propagation by longitudinal fission is common ( Carlgren and Hedgpeth 1952) and bifurcated tentacles can occur ( Hargitt 1908, 1912, Pax 1924, Corrêa 1964, present study).

Distribution.

Western Atlantic, from the northern coast of USA and Caribbean Sea, to the northern coast of Brazil ( Carlgren and Hedgpeth 1952, Varela 2002, Zamponi et al. 1998).

Remarks.

Of the 20 valid species of Anemonia , four species have been recorded in the Gulf of Mexico and Caribbean Sea ( Fautin 2013): Anemonia sargassensis , Anemonia melanaster (Verrill, 1901), Anemonia depressa Duchassaing & Michelotti, 1860, and Anemonia elegans Verrill, 1901. The anatomy described for Anemonia sargassensis is conflicting mainly in the presence of directives, siphonoglyphs, and marginal projections (e.g. Hargitt 1908, 1912, Pax 1924, Field 1949, Carlgren and Hedgpeth 1952). Just as in Field (1949), Carlgren and Hedgpeth (1952), and Corrêa (1964), we did not find directives in our specimens but 5-6 siphonoglyphs were present. Although some authors suggest that Anemonia sargassensis and Anemonia melanaster are synonymous ( Cairns et al. 1986, Ocaña and den Hartog 2002, Wirtz et al. 2003), further studies are necessary to establish the current taxonomic status of both species. Differences between the other two species of the genus in the region, Anemonia depressa and Anemonia elegans , and Anemonia sargassensis are not clear based on the scarce information available and also require further revision.