New gnathiid isopod crustaceans (Cymothoida) from Heron Island and Wistari Reef, southern Great Barrier Reef Author Svavarsson, Jörundur Author Bruce, Niel L. text Zootaxa 2019 2019-05-22 4609 1 31 67 journal article 26729 10.11646/zootaxa.4609.1.2 a349f585-a56b-4aee-b082-58d671a15523 1175-5326 3150433 68F78949-4006-424B-8CA4-432CD2955264 Gnathia cornuta Holdich and Harrison, 1980 ( Fig. 18 A–E) Gnathia cornuta Holdich & Harrison, 1980 : 225 , fig. 4A–I. — Poore & Lew Ton, 2002 : 188 . Material examined . ♂ ( 3.1 mm ), Heron Island , ‘ Canyons’ , reef slope, 23°28.389’S , 151°57.835’E , 8 December 1979 , in dead coral, 7 m , coll. N.L. Bruce ( MTQ W10701) . 2 ♂ (3.1, 3.4 mm ), Wistari Reef , off northern side of reef, 7 November 1978 , in sediments, 22 m , coll. D. Fisk ( MTQ W10700) . Remarks. This species is easily recognized on basis of the large paraocular tubercle, with its two V-shaped ridges and the internal lobe of the mandible ( Fig. 18E ) having a coarse crenulation. The mandibular lobe is short ( Fig. 18A, B ) in some specimens, while in larger specimens it reaches almost to the margin of the blade. Additional characteristic of the species is a fine crenulation laterally on the basal neck of the mandible ( Fig. 18B, C ). This is the first report of the species from Heron Island. The species was previously only recorded from the Pallarenda, Townsville, Northern Queensland. Distribution. Northern Queensland (Townsville, Heron Island); from the intertidal to depths of 22 m .