Bioacoustics of Cancellus heatherae

Remarks. The three other known western Atlantic species of Cancellus , C. spongicola , C. viridis , and C. orna-tus , all range into the eastern Gulf of Mexico or waters off Yucatan , and may in some settings occur sympatrically with C. heatherae n. sp. However, they are readily distinguished by morphology, even when separations cannot be based upon the distinctive coloration of fresh specimens. As in C. ornatus and C. viridis , the frontal rim of the carapace shield in C. heatherae n. sp. is continuous between the blunt lateral projections ( Fig. 1A ), extending continuously across the concave margin behind each eye and crossing the rostrum, and thus distinct from the subdivided front, interrupted behind each eye ( Mayo 1973 : fig. 2a) in C. spongicola . Also, while the lower palms of the chelipeds are to varied degrees, rugose in C. ornatus , C. viridis and C. heatherae n. sp. , none of these three species has a distinctly circumscribed patch of stridulating ridges on this surface comparable to that found in C. spongicola ( Mayo 1973 : fig. 3a). Morphological separation of C. heatherae n. sp. from C. ornatus can in turn be based on the former having paired spines arming the tip of each ocular acicle, as in C. viridis , rather than a single spine as in C. ornatus . However, the anterior rim of the cephalothoracic shield does not match that of C. viridis , being flattened, much as in C. ornatus , rather than inflated. Finally, the shape of the pleon, despite its soft texture, clearly appears more elongate in C. heatherae n. sp. than in any of its western Atlantic congeners, both pre- and post-preservation. The longitudinal groove or fold along the left side of the pleon in the holotype of this new species does not appear to be an artifact or abnormality, and thus is considered another distinguishing feature. For the other three species, the pleon is described as spherical to ellipsoid, with no mention of a fold or groove ( Mayo 1973 ). Finally, the female pleopods appear to be striking larger in relative size on the pleon of C. ornatus ( Fig. 3H ), than in the female holotype of C. heatherae n. sp. ( Fig. 3A ) or examined females of C. viridis ( Fig. 3F ). With only one specimen of C. heatherae n. sp. to judge from, it cannot for present be determined whether this might vary with size or maturation. For fresh specimens, the conspicuous orange coloration ( Fig. 3 A–D) readily distinguishes C. heatherae n. sp. from its two morphologically closest western Atlantic relatives, C. viridis and C. ornatus . Cancellus viridis , named for the green pigment of its patterning ( Fig. 3E, F ; Mayo 1973 : 30 , 33), consistently exhibits grades of this color in the types and specimens collected since its original description, and none of these specimens was noted to have extensive orange pigmentation. The coloration of C. heatherae n. sp. is also in stark contrast to that of C. ornatus in which pigmentation ranges from deep scarlet over the ocular peduncles, proximal surfaces of the ambulatory legs, and much of the dorsal thoracic integument, to varied shades speckled or diffuse brick red elsewhere, including on the pleon ( Fig. 3G, H ).