Gnathia trimaculata n. sp. (Crustacea: Isopoda: Gnathiidae), an ectoparasite found parasitising requiem sharks from off Lizard Island, Great Barrier Reef, Australia

Abstract

Gnathia trimaculata n. sp. is described from one black tip reef shark Carcharinus melanopterus Quoy & Gaimard and four grey reef sharks C. amblyrhynchos Bleeker collected off Lizard Island, Great Barrier Reef, Australia. Third-stage juveniles (praniza 3) were maintained in fresh seawater until they moulted into adults. Male adults emerged seven days post-removal (d.p.r) of pranizae from host fishes, whereas the female pranizae completed their moult into adult females 24 d.p.r. Distinctive features include the relatively large size of all stages and the unique mediofrontal process of the male, which is divided into two lobes forming a key-hole shape between them. The female frontal border is characterised by paired simple, pappose setae on the sides of the mid-dorsal area, as well as four long, pappose setae on the mid-dorsal region. The pranizae have eight teeth on each mandible. Live pranizae have stripes and three pairs of distinctive black spots within yellow circles on the sides of the pereonites and this pigmentation pattern persists in the adults. This represents the second description of a gnathiid parasitising elasmobranchs off Australia.

168 million years old “marine lice” and the evolution of parasitism within isopods

“…In representatives of Aegidae and Cymothoidae the maxillula is also elongated, as it is in larval, parasitic forms of Gnathiidae [12, 68–70]. The structure seen in the fossil could thus be interpreted as the maxillula.…”

Description of a Small-headed Gnathiid Isopod (Crustacea), <i>Gnathia capitellum</i> sp. nov., from Coastal Japan

“…Of 24 Gnathia species known from Japanese coastal and adjacent waters, larval morphologies have been described in 12 species (Nunomura and Honma 2004;Tanaka 2004;Ota et al 2007;Coetzee et al 2008Coetzee et al , 2009Ota and Hirose 2009a, b;Ota 2011Ota , 2014Ota , 2015. Most of the species (10) have been reported from elasmobranch fishes.…”

Three new gnathiid species with larvae ectoparasitic on coastal sharks from southwestern Japan (Crustacea: Isopoda)

“…had relatively large eyes and the inner margins of the eyes reached the base of the antenna while the distal margins were close to the base of the antenna. In most other species, the inner margins of the eyes do not reach the base of the antenna and the base of the antenna and the distal margin of the eyes are separated by a space (Smit & Davies 2002;Coetzee et al 2009;Ota & Hirose 2009a;Ota, 2011). Gnathia grandilaris also has relatively large eyes but its pleotelson is narrower than that of the present species (Coetzee et al 2008).…”