Paradexamine saxeta Myers, 2009, sp. nov.
Creators: name: Myers, Alan A.
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Dexaminidae
Paradexamine
Paradexamine saxeta

description: <i>Paradexamine saxeta</i> sp. nov. (Figs 19, 20) <b>Type Material.</b> Holotype, female, 2.0 mm, AM P 70577, 200 m off Research Beach (14°40.83'S 145°26.75E), coarse biogenic sand with seagrass, 2.5 m, J. Just (QLD 1626). Paratype, 1 male, AM P78006, same data as holotype. <b>Additional material examined.</b> 1 female, AM P70648 (QLD 1634); 3 males, 1 female, 2 juveniles, AM P70704 (QLD 1637); 1 female, AM P70935 (QLD 1688); 1 male, 2 juveniles, AM P78007 (QLD 1732); 1 male, AM P71099 (QLD 1733); 1 female, AM P71259 (QLD 1771); 1 male, AM P71330 (QLD 1778); 3 females, AM P78009 (SEL /LZI-2-3); 1 female, AM P78008 (SEL /LZI-2-4); 2 females, AM P78010 (SEL / LZI-5-2). <b>Type Locality.</b> Off Research Beach, Lizard Island, Queensland, Australia (14°40.83'S 145°26.75E'). <b>Etymology.</b> From the Latin 'saxetus' = a rocky place, referring to the Great Barrier Reef. <b>Description.</b> Based on holotype, female, 2.0 mm, AM P70577. <b>Head.</b> <i>Head</i> lateral lobes acute or subacute. <i>Eye</i> large, about half or less length of head, with black central core. <i>Antenna 1</i> peduncle article 1 without process on posterior margin. <i>Antenna 2</i> shorter than body length; peduncle article 4 slender, parallel sided, weakly setulose; flagellum with about 20 articles. <i>Mandible</i> palp absent; incisor process with robust setal row. <i>Maxilla 1</i> palp elongate, more than four times as long as broad. <i>Maxilliped</i> palp 4-articulate. <b>Pereon.</b> <i>Gnathopod 1</i> carpus subequal in length with propodus; propodus not greatly expanded distally. <i>Gnathopod 2</i> carpus elongate, slender, longer than propodus. <i>Pereopods 3–7</i> simple or scarcely prehensile. <i>Pereopod 3</i> coxa, posterodistal corner rounded; dactylus more than half length of propodus. <i>Pereopods 5–7</i> of uniform morphology. <i>Pereopod 5</i> basis subrectangular, with posterodistal lobe, anterior margin with short robust setae. <i>Pereopod 6</i> basis pyriform, broadest proximally, posteroproximal margin convex, with few small robust setae, posterodistal margin concave, smooth. <i>Pereopod 7</i> coxal gill present; basis slender or moderately expanded, much longer than broad, posterodistal margin, smooth or weakly serrated. <b>Pleon.</b> <i>Segments</i> with the following dorsal spine arrangement (from urosomite 1 forwards): 1.3.0.0.0. <i>Epimeron 2</i> posteroventral corner produced into a weak spine. <i>Epimeron 3</i> posterior and ventral margins smooth, with a single strong posteroventral spine. <i>Urosome</i> with urosomites 2–3 fused. <i>Urosomite 1</i> with dorsal spine only. <i>Uropod 3</i> rami lacking long fine setae. <i>Telson</i> lobes distally serrated, each lobe with multiple serrations of uneven size and shape, without distal spine, without subdistal robust seta, with subdistal slender seta. <b>Male</b> (sexually dimorphic characters). Based on paratype, male, 2.2 mm, AM P78006. <i>Eye</i> huge, more than half length of head. <i>Antenna 2</i> length unknown; peduncle article 4 broader proximally, finely setulose; flagellum unknown. <i>Uropod 3</i> rami with many long fine setae. <b>Habitat.</b> Sand and rubble with coral patches. <b>Remarks.</b> The poorly developed spines on the pleon of this material, together with its relatively small size, suggests it may be juvenile. However, it does not appear to be a juvenile of any of the other currently known GBR species and the male paratype has the enlarged eye, setose peduncle article 4 of antenna 2 and setose rami of uropod 3 that are characteristic of adult males. The strongly excavate posterodistal margin of the basis of pereopod 6 is not described for any other Australian species, although it occurs in a somewhat less exaggerated state in <i>P. linga</i> J.L. Barnard, 1972a. <i>Paradexamine saxeta</i> differs from <i>P. linga</i> in the more slender basis of pereopod 7 and in the much less acute lateral cephalic lobe. It also lacks robust setae on the ventral margin of epimeron 3. These are well-developed in <i>P. linga</i>. <b>Distribution.</b> <i>Australia</i>. Queensland: Research Beach, Lizard Island (current study).
description: Published as part of <i>Myers, Alan A., 2009, Dexaminidae *, pp. 393-424 in Zootaxa 2260 (1)</i> on pages 418-420, DOI: 10.11646/zootaxa.2260.1.20, http://zenodo.org/record/5319784
description: {"references": ["Barnard, J. L. (1972 a) Gammaridean Amphipoda of Australia, Part I. Smithsonian Contributions to Zoology, 103, 1 - 333."]}