Bunodosoma cavernatum

Diagnosis. Fully expanded oral disc and tentacles to 20 - 38 mm in diameter. Oral disc 10 - 22 mm in diameter, smooth, brown-yellowish, brown-reddish or pale olive-green, sometimes with white or yellowish radial stripes in endocoelic spaces of first two or three tentacular cycles (Figure 5 A, B). Tentacles hexamerously arranged in five cycles (about 96 in number), smooth, simple, conical, moderately long (3 - 5 mm in length), tapering distally, inner ones longer than outer ones, contractile, olive-green, reddish or pale-orange (Figure 5 A, B), often with white or yellowish spots on oral side and sometimes with purple flashes. Deep fosse (Figure 5 I). Forty-eight endocoelic rounded marginal projections forming acrorhagi (Figure 5 C, I) with holotrichs and basitrichs. Column cylindrical, 12 - 22 in diameter and 7 - 15 mm in height, densely covered with rounded vesicles, arranged in 96 longitudinal rows from margin to limbus (Figure 5 C, G). Pedal disc well-developed, 12 - 19 mm in diameter (Figure 5 C). Column and pedal disc light-brown, orange, reddish, yellowish or olive-green. Mesenteries hexamerously arranged in four cycles (48 pairs in specimens examined): first, second and some mesen teries of third cycle perfect, others imperfect; same number of mesenteries distally and proximally. All mesenteries fertile (except directives); gonochoric; oocytes and spermatic cysts well-developed in specimens collected in January and May (Figure 5 E). Two pairs of directives each attached to a well-developed siphonoglyph (Figure 5 D). Retractor muscles strong and restricted; parietobasilar muscles well-developed with a relatively long free mesogleal pennon (Figure 5 E). Basilar muscles well-developed (Figure 5 H). Marginal sphincter muscle endodermal, strong and circumscribed (Figure 5 I). Longitudinal muscles of tentacles ectodermal (Figure 5 F). Zooxanthellae present. Cnidom: basitrichs, microbasic b- and p-mastigophores, holotrichs and spirocysts (Figure 5 J-T; see Table 2).

Distribution. Western Atlantic, from North Caroline to Barbados; along the Caribbean Sea and Gulf of Mexico (Carlgren and Hedgpeth 1952); and Caroline Islands, Micronesia (Bosc 1802). This is the first record for the coast of Mexico; found in the VRS (see Table 1).