Aldisa pikokai Bertsch and Johnson, 1982

Yonow, Nathalie, Anderson, R. Charles & Buttress, Susan G., 2002, Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean, Journal of Natural History 36 (7), pp. 831-882 : 843

Aldisa pikokai Bertsch and Johnson, 1982

(®gures 4c, 6C, D)

Aldisa pikokai Bertsch and Johnson, 1982: 208 , ®gures 1, 2, 6±8; Millen and Gosliner, 1985: 209, ®gures 6H, 12.

Halgerda rubra Bergh : Kay and Young, 1969: 194 (part).

Material. Chag96/90: 183 7 mm; Three Brothers, Great Chagos Bank; 2 March 1996; at 8 m depth.

Description. The red dorsal surface was smooth but with numerous raised red ridges forming a pattern of reticulations, the resulting polygons of which were smaller marginally than medially (®gure 4c). The raised ridges did not extend on to the mantle margin. The marginal depressions contained numerous black dots, whereas those medially contained few, with the exception of three roughly circular pits, one anterior to the rhinophores, one posterior to the rhinophores, and the third anterior to the gills. A pair of irregular light brown patches was present laterally, level with the second median dark pit. The rhinophore stalks and clubs were red, while the gills were light red with a light brown margin; tubercles were present around the rim of the gill pocket. The ventral surface was smooth, red with no markings either on the foot or hyponotum; the semi-circular head did not have oral tentacles and anterior foot margin was bilaminate without propodial tentacles.

It was not possible to determine the radular formula: the long bristle-like teeth, measuring approximately 280 m m, were tangled and impossible to count. The serrations at the distal end are present only on one side of the tooth; they continue around the tip and appear to be hollow (®gure 6C, D).