Riwo mizeui Lowry &amp; Stoddart 1995
Creators: name: Lowry, J. K.
name: Stoddart, H. E.
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Lysianassidae
Riwo
Riwo mizeui

description: <i>Riwo mizeui</i> Lowry &amp; Stoddart, 1995 (Figs 5, 6) <i>Riwo mizeui</i> Lowry &amp; Stoddart, 1995: 127, figs 17–19. <b>Material examined.</b> Female, 3.6 mm, AM P69376; male, 2.8 mm, AM P69377; 36 unsexed, AM P69378; (QLD 727). 1 unsexed, AM P69379 (QLD 683). <b>Type locality.</b> Wongad Natun reef, Madang Lagoon, Papua New Guinea, western South Pacific Ocean (5°08.31'S 145°49.36'E), 4 m depth. <b>Description.</b> Based on female, 3.6 mm, AM P69376. <b>Head and body</b>. <i>Body</i> without dorsal carina. <i>Head</i> lateral cephalic lobes subtriangular, with apically rounded margins; eyes oval. <i>Antenna 1</i> subequal to antenna 2; flagellum article 1 slightly longer than article 2, with weak 1-field callynophore, robust setae absent from proximal articles; calceoli absent; accessory flagellum with 4 articles. <i>Antenna 2</i> less than 40% of body length; peduncular article 3 long; calceoli absent. <i>Mouthparts</i> forming a subquadrate bundle. <i>Epistome</i> / <i>upper lip</i> separate, epistome less produced than upper lip, straight; upper lip produced, rounded apically. <i>Mandible</i> molar a small, smooth flap with finely setose margins; palp attached proximally, article 3 without A3–setae. <i>Maxilla 1</i> outer plate with 10 setal-teeth in reduced 6/5 arrangement; setal-tooth 7, left and right symmetrical, cuspidate distally; palp distal margin with apical robust setae and serrations. <i>Maxilliped</i> inner plates poorly developed, not reaching half the length of the outer plate; outer plates without apical robust setae; palp 4–articulate, article 4 well developed. <b>Pereon.</b> <i>Gnathopod 1</i> simple; coxa large, about as long as coxa 2, subrectangular with straight anterior margin; basis without setae along anterior margin; ischium short; carpus short (length 1.9 x breadth), subequal in length to propodus, without posterior lobe; propodus longer than broad, margins tapering; dactylus inner margin not serrated. <i>Gnathopod 2</i> chelate; carpus longer than (2.4 x) propodus; palm slightly obtuse; dactylus minute. <i>Pereopod 4</i> coxa with well developed posteroventral lobe. <i>Pereopod 5</i> coxa anterior lobe slightly deeper than posterior lobe; basis about as long as broad. <b>Pleon.</b> <i>Epimeron 3</i> posterior margin smooth, posterodistal corner narrowly rounded. <i>Urosomite 1</i> without anterodorsal notch, slightly rounded dorsally, without boss. <i>Uropod 1</i> rami subequal. <i>Uropod 2</i> rami subequal, inner ramus without marginal constriction. <i>Uropod 3</i> rami distinctly unequal, without plumose setae; outer ramus 2–articulate, article 2 short; inner ramus not reaching end of article 1 of outer ramus. <i>Telson</i> subequal in length and breadth, notched, without dorsal robust setae. <b>Male</b> (sexually dimorphic characters) based on male, 2.8 mm, AM P69377. Antenna 1 with weak 2-field callynophore; calceoli present. Antenna 2 calceoli present. <b>Habitat.</b> Scavenger living among soft and hard corals in 3 to 50 m depth. <b>Remarks.</b> According to Lowry &amp; Stoddart (1995) <i>Riwo mizeui</i> is a scavenger which occurs on living coral bottoms. It is the only lysianassid known from the Great Barrier Reef which has both a simple first gnathopod and distinctly unequal rami on uropod 3. <i>Pseudambasia acuticaudata</i> also has unequal rami on uropod 3, but the first gnathopod is weakly subchelate. <i>Riwo mizeui</i> differs from <i>Shoemakerella barnardi</i>, which also has a simple gnathopod 1, in the size of the eyes which cover most of the head (smaller in <i>S. barnardi</i>), the presence of robust setae on the distal margin of maxilla 1 palp (serrate in <i>S. barnardi</i>) and epimeron 3 which is narrowly rounded (broadly rounded in <i>S. barnardi</i>). Living specimens <i>R. mizeui</i> have a black-speckled chromatophore pattern on the body (body white in <i>S. barnardi</i>). <b>Distribution.</b> <i>Australia</i>. Queensland: Ashmore Reef (current study), inside Outer Barrier (current study). <i>Papua New Guinea</i>. Madang Lagoon (Lowry &amp; Stoddart 1995).
description: Published as part of <i>Lowry, J. K. &amp; Stoddart, H. E., 2009, Lysianassidae *, pp. 561-597 in Zootaxa 2260 (1)</i> on pages 568-571, DOI: 10.11646/zootaxa.2260.1.31, http://zenodo.org/record/5308147
description: {"references": ["Lowry, J. K. &amp; Stoddart, H. E. (1995) The Amphipoda (Crustacea) of Madang Lagoon: Lysianassidae, Opisidae, Uristidae, Wandinidae and Stegocephalidae. Records of the Australian Museum, Supplement, 22, 97 - 174."]}