Cirolana westbyi, (Isopoda: Cirolanidae) a new species in the 'Cirolana parva-group' from the Turneffe Atoll, Belize

Cirolana westbyi n. sp., a novel species in the 'Cirolana parva-group' is described from the Turneffe Atoll, Belize using an integrated molecular and morphological approach. The 18S ribosomal RNA gene for C. westbyi n. sp. and also for Cirolana parva Hansen, 1890 are provided, in addition to new primers, developed for the Cirolanidae 18S gene. The key morphological character for separating C. westbyi n. sp. from other Cirolana is the shape of the uropodal rami: the uropodal endopod is convex on the lateral side while the mesial side is straight. Comparison of the 18S gene shows that C. parva is 95.96% identical to C. westbyi n. sp. across 68% coverage, but due to two unique insertions ('INS-1' and 'INS-2') into the 18S gene of C westbyi n. sp., which may function as loop regions, they appear to be genetically distinct and different species. This is also supported by phylogenetic analysis, which also highlights some potential paraphyly between the three families, Cirolanidae, Aegidae and Corallanidae. Our morphological description of a new species of cirolanid along with a phylogenetic support using 18S sequence data for species within and around the Cirolanidae, provides greater context for the 'Cirolana parva-group'.