Quadrisegmentum triangulum Hirayama 1988
Creators: name: Guerra-García, José M.
name: Lowry, J. K.
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Caprellidae
Quadrisegmentum
Quadrisegmentum triangulum

description: <i>Quadrisegmentum triangulum</i> Hirayama, 1988 (Fig. 17) <i>Quadrisegmentum triangulum</i> Hirayama, 1988: 1089, figs 1–3. —Guerra-García, 2006: 440, fig. 39. <b>Material examined.</b> 1 male, ~ 7.7 mm, 1 female, ~ 5.5 mm, AM P61725 (QLD 1565). See station list for occurrences (Lowry &amp; Myers 2009) and Guerra-García (2006) for complete material examined. <b>Type locality.</b> West Islet, Ashmore Islands, north-west Western Australia (12º41.28'S 122º59.14'E), on gorgonian host, <i>Isis hippurus</i> Linnaeus, 18 m depth. <b>Description.</b> Based on 1 male, ~ 7.7 mm, 1 female, ~ 5.5 mm, AM P61725 <b>Head</b> and pereonites slender. <i>Head/pereonite 1</i> fused (suture absent), slightly concave along dorsal margin; eye large, distinctive, or large, protruding. <i>Antenna 1</i> well developed; slender, about 0.5 x body length; peduncle article 2 longest, article 3 straight; accessory flagellum absent; flagellum 0.4 x peduncular length or 0.5 x peduncular length, with more than 2 articles. <i>Antenna 2</i> 0.75 x antenna 1 length, slender; peduncle without setae; with more than 4 articles (5–7 articles). <i>Labrum</i> notched, forming rounded quadrilateral projections. <i>Mandible</i> right incisor with 5 teeth, right lacinia mobilis transformed into a plate, accessory setal row with 7 setae; molar absent; left incisor with 4 teeth, lacinia mobilis transformed into a serrated plate, with 3 trapezoid plates decreasing in size; palp 3–articulate, palp setal formula 1-0-1. <i>Maxilla 1</i> outer plate with 6 stout apical setal-teeth. <i>Maxilliped</i> inner plate smaller than outer plate; serrate distally; outer plate subequal to inner plate; palp article 2 scarcely setose on inner margin; palp article 4 not enlarged, not falcate. <b>Pereon</b>. Pereonites 2 to 7 not fused; pereonite 5 longest. <i>Pereonite 1</i> without projections. <i>Gnathopod 1</i> distinctly smaller than gnathopod 2; propodus triangular, palm begins 2/5 along posterior margin, smooth, without large, rounded knob proximally; dactylus curved, inner margin smooth. <i>Pereonite 2</i> without projections. <i>Gnathopod 2</i> situated near middle of pereonite 2; basis about 1.5 x length of pereonite 2, without anterodistal projection; ischium without anterodistal projection; propodus elongate, massive, anterodistal margin straight, without anterodistal triangular projection, without projections along mid-anterior margin; palm without proximal cavity filled with membranous sack, palm proximal projection with 2 robust (grasping) setae, palm margin concave, smooth, without hook-like projection at base of dactylus, with broad well developed distal shelf, without projection, without sinus, without midpalmar projection. <i>Pereonite 3</i> without projections. <i>Pereopod 3</i> well developed, with 6 articles. <i>Pereonite 4</i> without projections. <i>Pereopod 4</i> well developed, with 6 articles. <i>Pereopod 5</i> reduced or vestigial, with 4 slender articles. <i>Pereopod 6</i> basis longest followed by merus. <i>Pereopod 7</i> similar to pereopod 6. <i>Gills</i> on pereonites 2 to 4. <i>Pereonite 2</i> gill rounded. <i>Pereonite 3 gill</i> length about 2/3 of corresponding pereonite, straight, elongate, cylindrical. <i>Pereonite 4 gill</i> length about 2/3 of corresponding pereonite, straight, elongate, cylindrical. <b>Pleon</b>. <i>Uropod 1</i> present. <i>Uropod 2</i> ramus well developed. <b>Female</b> (sexually dimorphic characters). <i>Gnathopod 2</i> situated near anterior end of pereonite 2; basis (proximal-most article) subequal in length to pereonite 2; large; palm margin convex or straight. <b>Habitat.</b> Patch reefs, algae and coral rubble, associated with the hydroid <i>Halopteris buskii</i> and the sponge <i>Clathria reinwardti</i>, 2– 30 m. <b>Remarks.</b> <i>Quadrisegmentum triangulum</i> is one of the most abundant caprellid species on the Great Barrier Reef. <b>Distribution.</b> <i>Australia</i>: Queensland: off Coconut Beach; off Crystal Beach; Mangrove Beach, Blue lagoon; between Bird Islet and South Island; Chinamans Ridge, Watsons Bay; Mermaid Cove; Pidgin Point; North Point; south of "Washing Machine", north-east side of Lizard Island (Guerra-García 2006). Lord Howe Island. Middleton Reef (Guerra-García 2006). Western Australia: Ashmore Islands (Hirayama 1988). <i>Papua New Guinea</i>: Motupore Island and Madang (Guerra-García 2003a).
description: Published as part of <i>Guerra-García, José M. &amp; Lowry, J. K., 2009, Caprellidae *, pp. 290-327 in Zootaxa 2260 (1)</i> on pages 323-325, DOI: 10.11646/zootaxa.2260.1.12, http://zenodo.org/record/5320964
description: {"references": ["Hirayama, A. (1988) A ghost shrimp with four-articulate fifth pereopods (Crustacea: Caprellidea: Phtisicidae) from Northwest Australia. Zoological Science, 5, 1089 - 1093.", "Lowry, J. K. &amp; Myers, A. A. (2009) Foreword. In: Lowry, J. K. &amp; Myers, A. A. (Eds), Amphipoda of the Great Barrier Reef, Australia. Zootaxa, 2260, 17 - 108.", "Guerra-Garcia, J. M. (2003 a) Caprellids (Crustacea: Amphipoda) from Papua New Guinea, with the description of a new species. Helgoland Marine Research, 57, 100 - 109."]}