Two New Species of Quadrisegmentum (Phtisicidae: Amphipoda: Crustacea) from the Central Indo-Pacific, with Notes on the Type Species Q. triangulum Hirayama, 1988 Author Hughes, Lauren Elizabeth Author Takeuchi, Ichiro text Records of the Australian Museum 2016 2016-11-16 68 5 231 244 http://dx.doi.org/10.3853/j.2201-4349.68.2016.1663 journal article 10.3853/j.2201-4349.68.2016.1663 2201-4349 4676871 Quadrisegmentum triangulum Hirayama, 1988 Fig. 5 Quadrisegmentum triangulum — Hirayama, 1988: 1090– 1093 , figs. 1–3. not Quadrisegmentum triangulum . — Guerra-Garcia, 2003: 104–105 , fig. 9a. — Guerra-Garcia, 2006: 440 , fig. 39. —Guerra-Garcia & Lowry, 2009: 323–325 (= Q. yirrgay sp. nov. ). Type material examined . Paratypes 1 ♂ (no. 1) 8 mm , and 2 ♀♀ (nos. 2–3) 5.2 mm and unmeasured, NTM Cr. 00447, taken from gorgonian host, Isis hippuris Linnaeus, 1758 in 18 m on west islet of Ashmore Reef , Northwest Australia ( 12°14.28'S 122°59.14'E .), 24 July 1986 , coll. H. K. Larson. ( Holotype carcass and slide material not found, presumed lost) . Type locality . Ashmore Reef , Timor Sea , north-west Western Australia ( 12°14.28'S 122°59.14'E ) . Remarks . Examination of Q. triangulum type material recognizes the absence of projections on pereonite 2 in both sexes and also records the presence of anterolateral projections on the male pereonite 3. These anterolateral projections on pereonite 3 were not recorded in the original description by Hirayama (1988) . Additional material attributed to Q. triangulum by the first and second reviewer from Queensland, Australian and Papua New Guinea ( Guerra-García, 2003 , 2006 ), contained specimens where pereonite 2 projections were observed on males and females. This latter material was reassessed as part of this study and determined to be a separate species. These records are transferred to the new species name Q. yirrgay described below. The name Quadrisegmentum triangulum is once again restricted to the original type material and presently known only from the type locality. Distribution . Ashmore Reef ( Hirayama, 1988 ).