ABSTRACT
Some nudibranchs are predators of scleractinian corals, but little is known about their diversity. Here we describe Phestilla fuscostriata sp. nov., the first species of nudibranch that preys on Pavona decussata, a structure-forming agariciid species in the South China Sea. This new species has a white body with brown pigmentation on the dorsum and cerata, and exhibits excellent mimicry by matching the colour of its coral host. The nudibranch lays crescent-shaped egg masses on the coral surface, where the embryos develop and hatch in 2-3 weeks. This new species possesses a large number of cerata that are arranged in widely-spaced rows, with each row having one dorsal ceras and zero to several ventral cerata, which distinguishes it from all other congeneric species. A comparison of the mitochondrial COI and 16S rRNA genes and the nuclear H3 gene between P. fuscostriata sp. nov. and other Phestilla spp. found that their interspecific distances are large enough to justify the recognition of the new species.
ABSTRACT
Members of the nudibranch genus Phestilla are common predators of scleractinian corals, but currently this genus has 10 described species only. Here we describe Phestilla goniophaga sp. nov., the first formally named predatory nudibranch species of the stony corals from the genus Goniopora. The new species can be distinguished from its congeneric species by the large number of long cerata (up to 16 rows and 23 cerata per row), and white rounded hump on the notum. The hump resembles the mouth of the coral poly, while the cerata resemble the coral tentacles. The egg masses of P. goniophaga sp. nov. are unique among Phestilla spp. egg masses in being bright orange in color, and forming a coiled ribbon. Analysis of the COI, 16S rRNA and H3 genes of P. goniophaga sp. nov. also showed that this species is distinct from other congeneric species.
