Hypselodoris iba Gosliner & R. F. Johnson, 2018

Location: YKK, Mabul, Borneo, Malaysia
Date: 2016/12/30
Length: 40mm
Depth: 15.0m
Water temperature: 28.0℃

Description

Living animals are large, reaching 70 mm in length. The body is wide anteriorly and tapers to a narrow, rounded posterior. Six to eight unipinnate gill branches with a white base and orange outer portion arise from a well-elevated gill pocket. Rhinophores are orange with 20-46 lamellae. The colour pattern occurs in two distinct morphs. In the first morph the body is uniformly purple, with a uniformly wide opaque white or orange marginal band; rhinophores are uniformly orange or orange to purplish orange. The second morph is generally off-white to beige with a thin white marginal band that becomes orange anteriorly and posteriorly, blood-red blotches on the central notum and base of the gill pocket and rhinophore sheaths, and a purple band near the opening of the rhinophore sheaths. Specimens of the two morphs have been observed copulating with each other.

Distribution

Known from Indonesia and the Philippines.

Etymology

Named for the Tagalog word iba, meaning different or distinctive.

Remarks

Hypselodoris iba has been considered as a synonym of Hypselodoris bullockii or as an undescribed species. Despite their strikingly different appearance, the two colour morphs of H. iba show very little genetic divergence (0.3-0.6% in COI) and have been observed copulating, confirming conspecificity. H. iba is a member of a large clade that also includes Hypselodoris reidi, Hypselodoris jacksoni, Hypselodoris cerisae, Hypselodoris krakatoa, Hypselodoris regina and Hypselodoris lacuna; none of these has a colour pattern similar to either morph of H. iba. The most reliable way to distinguish H. iba from members of the H. bullockii clade is the presence of mantle glands in H. iba, which are absent in the H. bullockii clade. The type locality is Aphol's Reef, Tingloy, Maricaban Island, Batangas, Philippines, 35 m depth.