Lebrunia danae

Natural history. — Lebrunia danae lives in shallow waters inside holes or crevices of calcareous skeletons among corals and rocks, often between 2 – 12 m depth, in the fore and back-reef zones, although it has been reported down to 60 m (Ocaña et al. 2007). Lebrunia danae is associated with the caridean shrimps Thor amboinensis, Periclimenes yucatanicus, and Ancylomenes pedersoni (Manjarrés 1978; Cairns et al. 1986; Ritson-Williams & Paul 2007). During the day pseudotentacles (incapable of feeding) remain fully expanded, allowing zooxanthellae to capture sunlight. During night, pseudotentacles are contracted and the true feeding tentacles are expanded (Sebens & DeRiemer 1977). The nematocysts batteries in the vesicles of the pseudotentacles are hypothesized to have a defensive function (Sebens & DeRiemer 1977). The sting of this anemone can be highly irritating to humans (McMurrich 1889 a; Verrill 1905; Cairns et al. 1986; Ocaña et al. 2007).

(Figure 6, Table 2)

Diagnosis. — Fully expanded tentacles and oral disc 45 – 95 mm in diameter. Oral disc 10 – 25 mm in diameter, smooth, flat, wider than column, light brown, semi-transparent (Figure 6 B). Tentacles about 48, hexamerously arranged in four cycles, smooth but striated in appearance, tapering distally, inner ones longer than outer ones, contractile, light brown but whitish towards tips, with small white dots (Figure 6 B – C). Column cylindrical, smooth, 8 – 40 mm in diameter and 10 – 35 mm in height. Column distally with 4 – 6 branched outgrowths (pseudotentacles) with tips forked, and small round vesicles among ramifications (Figure 6 D); vesicles with batteries of macrobasic p - amastigophores. Pseudotentacles light to dark brown, vesicles white or bluish (Figure 6 A). Pedal disc well developed, 12 – 50 mm in diameter, wider than column. Pedal disc and column light brown or beige, semi-transparent (Figure 6 D). Mesenteries hexamerously arranged in four cycles (48 pairs in specimens examined): first and second cycles perfect and fertile, others imperfect and sterile. Same number of mesenteries distally and proximally. Hermaphroditic (Figure 6 F). Two pairs of directives each attached to a well developed siphonoglyph (Figure 6 E). Retractor muscles strong, diffuse to restricted; parietobasilar muscles poorly developed (Figure 6 E). Basilar muscles developed. Marginal sphincter muscle absent. Longitudinal muscles of tentacles ectodermal. Zooxanthellae present, mainly in pseudotentacles. Cnidom: basitrichs, macrobasic p - amastigophores, microbasic p - amastigophores, and spirocysts (Figure 6 G – O; see Table 2).

Remarks. — Currently Lebrunia contains two valid species, both reported in the Caribbean Sea (Fautin 2011). The species differ in the branched pseudotentacles: those of L. danae are longer, dark brown, and have forked ends, whereas those of L. coralligens are shorter, bright bluish-gray, and have rounded ends (Varela 2002). We did not observe the weak longitudinal muscles in the distal column cited in the generic diagnosis (Carlgren 1949).

Distribution. — Lebrunia danae occurs from Bermuda to Brazil, along the entire Caribbean Sea (see Table 1). In the Mexican Caribbean, Lebrunia danae is reported in Puerto Morelos and Cozumel reefs (INE 2000; Jordán- Dahlgren 2008), but these represent the first records in Punta Cancún, Punta Nizuc, Akumal, Xcalak, and Isla Contoy reefs.

Material examined. — Puerto Morelos (20 ° 49 ’ 53.2 ” N, 86 ° 52 ’ 28.02 ” W; 4 specimens); Punta Cancún (21 ° 9 ’ 10.5 ” N, 86 ° 44 ’ 41.20 ” W; 2 specimens); Punta Nizuc (21 ° 8 ’ 15.65 ” N, 86 ° 44 ’ 20.57 ” W; 1 specimen); Akumal (20 ° 23 ’ 37.03 ” N, 87 ° 18 ’ 44.51 ” W; 1 specimen), Xcalak (18 ° 13 ’ 4.7 ” N, 87 ° 49 ’ 48.8 ” W; 2 specimens); Isla Contoy (21 ° 28 ’ 16.98 ” N, 86 ° 47 ’ 27.87 ” W; 1 specimen).