Anthopleura pallida Duchassaing & Michelotti, 1864

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 : 82-83

Anthopleura pallida Duchassaing & Michelotti, 1864 Figure 4, Table 2

Anthopleura pallida Duchassaing and Michelotti 1864: 32-33; Pl. V, fig. 10.

Anthopleura Pallida [sic]: Duchassaing 1870: 20.

Gyractis pallida non Boveri 1893: 251-252.

Actinioides pallida : Duerden 1897: 453.

Actinoides pallida : Verrill 1900: 558.

Bunodactis stelloides catenulata Verrill 1905: 263.

Anthopleura pallida non Carlgren, 1949: 53.

Anthopleura catenulata : Cairns, den Hartog and Arneson 1986: 177-178; Pl. 51.

Material examined.

Alacranes reef (22°22'54"N, 89°40'59"W; four specimens).

Diagnosis.

Fully expanded oral disc and tentacles 10-19 mm in diameter. Oral disc narrow, smooth, 3-8 mm in diameter, pale green or gray (Figure 4A). Tentacles hexamerously arranged in three cycles (24 in number), smooth, slender, relatively short (to 4-9 mm), tapering distally, inner ones longer than outer ones, contractile, whitish or gray, translucent, oral side with opaque white roundish spots (Figure 4A, B). Fosse well marked (Figure 4E). Column cylindrical, relatively elongate, 3-6 mm in diameter and 6-12 mm in height, with 12 longitudinal rows of verrucae from mid-column to distal margin (Figure 4B, G). Twelve endocoelic marginal projections forming acrorhagi (Figure 4B, E) with holotrichs, basitrichs, microbasic p-mastigophores, and spirocysts. Pedal disc well-developed, 4-8 mm in diameter, slightly wider than column (Figure 4B). Pedal disc and column white to pale green (Figure 4B). Mesenteries hexamerously arranged in 2-3 cycles: only first cycle perfect or first two cycles perfect and third imperfect; same number of mesenteries distally and proximally (12-32 pairs in specimens examined). Only first two cycles fertile (except directives); gonochoric (?), only spermatic cysts observed in specimens examined (Figure 4F). Two pairs of directives each attached to a well-developed siphonoglyph (Figure 4C). Retractor muscles diffuse; parietobasilar muscles well-developed with short mesogleal pennon (Figure 4D). Basilar muscles well-developed (Figure 4H). Marginal sphincter muscle endodermal, weak and diffuse (Figure 4E). Longitudinal muscles of tentacles ectodermal. Cnidom: basitrichs, microbasic b- and p-mastigophores, holotrichs, and spirocysts (Figure 4 I–X; see Table 2).

Natural history.

Anthopleura pallida inhabits the intertidal to shallow subtidal zone attached to coral on sandy shores, at 0.5 m. It is azooxanthellate and it broadcast spawns ( Daly and den Hartog 2004).

Distribution.

Western Atlantic, from Bermuda ( Verrill 1900) to Virgin Islands ( Duchassaing and Michelotti 1864). This is the first record for the coast of Mexico; found in Alacranes reef (see Table 1).

Remarks.

Currently there are three valid species of Anthopleura in the Gulf of Mexico and Caribbean Sea: Anthopleura krebsi (Duchassaing & Michelotti, 1860), Anthopleura texaensis (Carlgren and Hedgpeth, 1952), and Anthopleura pallida ( Daly and den Hartog 2004). Anthopleura pallida is distinguished mainly in column color and shape, and the arrangement of verrucae in rows, only present from the margin to the mid-column ( Daly and den Hartog 2004). However, in Anthopleura krebsi and Anthopleura texaensis , the column is stout rather than elongate, and the verrucae are arranged in rows along the entire column length, from margin to limbus ( Daly and den Hartog 2004). Although we found the marginal sphincter muscle diffuse rather than circumscribed-diffuse, all other features including external and internal anatomy and cnidae fit well with the redescription of Anthopleura pallida by Daly and den Hartog (2004).