Cymadusa alyxis Hughes &amp; Lowry 2009, sp. nov.
Creators: name: Hughes, L. E.
name: Lowry, J. K.
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Ampithoidae
Cymadusa
Cymadusa alyxis

description: <i>Cymadusa alyxis</i> Hughes &amp; Lowry sp. nov. (Figs 11, 12, Pl. 1D) <b>Type material.</b> Holotype, male, 7.7 mm, 6 slides, AM P76245 (QLD 1716) Picnic Beach, Palfrey Island, near Lizard Island (14°41.69’S 145°26.89’E), green alga <i>Codium</i> sp., reef flat, 2 m, T. Krapp-Schickel, 27 February 2005. Paratypes: female, 8.7 mm, 5 slides, AM P76246 (QLD 1716); 7 unsexed, AM P71098 (QLD 1716). <b>Additional material examined.</b> 1 dissected male ‘A’, 3 slides, AM 76247 (QLD 1632); 1 dissected female ‘C’, 3 slides, AM P76248 (QLD 1632); 1 dissected juvenile ‘B’, 4 slides, AM P76249 (QLD 1632); 8 unsexed, AM P70166 (QLD 1704); 2 unsexed, photo 4, AM P70949 (QLD 1704); 6 unsexed, AM P71014 (QLD 1705); 4 unsexed, AM P71265 (QLD 1757); 2 unsexed, AM P71295 (QLD 1769); 13 unsexed, AM P76250 (SEL /LZI-5-2). <b>Type locality.</b> Picnic Beach, Palfrey Island, near Lizard Island, Queensland, Australia (14°41.69’S 145°26.89’E), living on green alga <i>Codium</i> sp., 2 m. <b>Etymology.</b> From the Latin <i>alyxis</i> – ‘an escape’ – in reference to the history of the type locality, Lizard Island, where the early English explorer Captain Cook climbed to the top of the island and charted a passage out of the Great Barrier Reef. <b>Description</b>. Based on holotype, male, 7.7 mm, AM P76245. <b>Head.</b> <i>Antenna 1</i> primary flagellum 20 articles, accessory flagellum with 1 article. <i>Antenna 2</i> peduncle not densely setose on ventral margin, flagellum 24 articles. <i>Upper lip</i> lateral margins each with midlateral notch. <i>Mandible</i> molar well developed, triturating, accessory setal row with 8 serrate setae; palp 3–articulate, article 3 marginally setose; article 1 subequal in length to article 2; article 2 shorter than article 3; article 3 longer than article 1. <i>Lower lip</i> outer plates notched, lateral lobe distinctly longer than medial lobe; mandibular lobe with curved margins, rounded apically. <i>Maxilla 1</i> inner plate with 4 setae. <i>Maxilla 2</i> inner plate narrower than outer plate; palp article 2 broad. <i>Maxilliped</i> outer plate with row of large robust setae along medial margin. <b>Pereon.</b> <i>Coxae 1–4</i> deeper than broad. <i>Gnathopod 1</i> smaller than gnathopod 2; coxa distinctly larger than coxa 2, produced, anterior margin straight, anteroventral corner rounded, with tuft of long slender setae in posteroventral corner; basis shorter than coxa, anterodistal lobe absent, without setae; merus posterodistal lobe subacute; carpus about 2 x as long as broad, subequal in length to propodus, anterior margin without setae, posterior margin straight; propodus broad, subrectangular; palm acute, straight, with obtuse posterodistal corner, with 1 robust seta defining palm; dactylus subequal to palm, inner margin crenate. <i>Gnathopod 2</i> coxa with tuft of long slender setae in posteroventral corner; merus with short, acute anterodistal lobe; carpus much shorter than propodus, cup-shaped; propodus broad, less than 1.5 x as long as broad, subrectangular, not produced into an anterodistally setose lobe; palm acute, straight, without palm defining robust setae; dactylus slightly shorter than palm, tapering evenly, apically acute, inner margin crenate. <i>Pereopods 3–4</i> basis narrow; merus subequal in length to carpus. <i>Pereopods 5–7</i> weakly prehensile. <i>Pereopod 5</i> basis with medial slender setae; distal articles slender; propodus not expanded distally, with 2 anterodistal striated robust setae. <i>Pereopod 6</i> basis posterior margin rounded proximally, straight distally, with several marginal robust setae; distal articles slender; propodus not expanded distally, with 2 anterodistal striated robust setae. <i>Pereopod 7</i> similar to pereopod 6. <b>Pleon.</b> <i>Epimera 2–3</i> with small acute cusp. <i>Uropod 1</i> peduncle with 3–8 robust setae, with long fringe of slender setae (greater than 0.5 x length of peduncle), with large, acute distoventral spine; outer ramus length about 5–6 x as long as broad, with 6 lateral robust setae; inner ramus with 6 lateral robust setae. <i>Uropod 2</i> peduncle with 4 robust setae; outer ramus with 10 lateral robust setae; inner ramus with 9 lateral robust setae. <i>Uropod 3</i> peduncle longer than broad, less than 2 x length of rami, without marginal slender setae, with 5 distal robust setae, with 4 distal slender setae; outer ramus with 2 large striated recurved distal robust setae, with 1 lateral robust seta and 8 lateral slender setae; inner ramus with 5 distal robust setae, 9 distal slender setae and 1 lateral seta. <i>Telson</i> subtrapezoidal, apically truncated, with small apical cusp on each distolateral corner, with oblique medial rows of slender setae, with 1 pair of lateral slender setae, and with 2 pair of lateral and one pair of apical plumose setae. <b>Female</b> (sexually dimorphic characters). Based on paratype, female, 8.7 mm, AM P76246. <i>Gnathopod 1</i> subequal is size to gnathopod 2; basis subequal in length to coxa, anterodistal lobe rounded, with 1 slender seta; carpus anterior margin with slender setae; propodus subtriangular; palm straight. <i>Gnathopod 2</i> propodus with 1 robust palm defining seta. <b>Colour.</b> Body clear to white with mottle brown patches and white spots. <b>Habitat.</b> Green alga, <i>Codium</i> sp. <b>Remarks.</b> <i>Cymadusa alyxis</i> <b>sp. nov.</b> is similar to <i>C. panwa</i> Peart, 2002, from Thailand and <i>C. vadosa</i> Imbach, 1967, from Vietnam. In <i>C. alyxis</i> the male gnathopod 2 palm is straight, and in <i>C. panwa</i> and <i>C. vadosa</i> it is sinusoidal. These species can also be differentiated by the anterior margin of the gnathopod 1 coxa, which is convex in <i>C. alyxis</i>, straight in <i>C. panwa</i> and <i>C. vadosa</i>. The anterodistal corner of the gnathopod 1 coxa is also more broadly rounded in <i>C. alyxis</i> than in the other two species. <i>Cymadusa alyxis</i> can be distinguished from other GBR <i>Cymadusa</i> species by the male gnathopod 2 which is not densely setose and has a straight, entire propodus palm. Adults of <i>C. alyxis</i> are particularly large amphipods, 12+ mm. Subadult males (~ 10 mm) have a gnathopod 2 palm which is slightly sigmoidal. <b>Distribution.</b> <i>Australia</i>. Queensland: Lizard Island (current study).
description: Published as part of <i>Hughes, L. E. &amp; Lowry, J. K., 2009, Ampithoidae *, pp. 153-219 in Zootaxa 2260 (1)</i> on pages 171-174, DOI: 10.11646/zootaxa.2260.1.8, http://zenodo.org/record/5322208
description: {"references": ["Peart, R. A. (2002) New species of Ampithoidae (Crustacea, Amphipoda, Corophioidea) from the eastern Andaman Sea. Phuket Marine Biological Center Special Publication, 23 (1), 229 - 252.", "Imbach, M. C. (1967) Gammaridean Amphipoda from the South China Sea. Naga Report, 4 (1), 39 - 167."]}