First record and molecular characterisation of two Gnathia species (Crustacea, Isopoda, Gnathiidae) from Philippine coral reefs, including a summary of all Central-Indo Pacific Gnathia species

Abstract

Due to their unusual life cycle that includes parasitic larval and free living adult stages, gnathiid isopods are typically overlooked in biodiversity surveys, even those that focus on parasites. While the Philippines sits within the region of highest marine biodiversity in the world, the coral triangle, no gnathiid species have been identified or described from that region. Here we present the first records of two gnathiid species collected from the Visayas, central Philippines: Gnathia malaysiensis Müller, 1993, previously described from Malaysia, and G. camuripenis Tanaka, 2004, previously described from southern Japan. This paper provides detailed morphological redescriptions, drawings and scanning electron microscope images as well as the first molecular characterisation of both species, Furthermore, a summary of the Central-Indo Pacific Gnathia species is provided.

 Gnathia pipinde sp. nov. (Crustacea, Isopoda, Gnathiidae), a temporary parasite of the pufferfish, Amblyrhynchotes honckenii, from temperate southern Africa

“…nov. These are G. falcipenis from the Great Barrier Reef, Australia; G. cooki from Morea, Society Islands in the tropical Pacific; and G. camuripenis from southern Japan and the Philippines (Shodipo et al 2021). According to Holdich and Harrison (1980), the mediofrontal process of G. falcipenis is conical and, thus, distinctly different from the bifid mediofrontal process of G. pipinde sp.…”

“…Gnathiid isopods have traditionally been described from the free-living adult males collected from dredge sampling, elutriation and sorting of coral rubble, from sponge collections, and other standard techniques used to collect small marine crustaceans. However, since the early 2000s, new gnathiid species have been described by moulting final (P3) larval stages into adults, either collected by light (Farquharson et al 2012) and baited traps (Shodipo et al 2021) or collected directly from the host (Ferreira et al 2010). This latter method also provides the opportunity to obtain morphological and ecological information on the larval stage as well as host information that is generally lacking for most species of gnathiids.…”