Gbroidea dingaalana Lowry &amp; Azman 2008, sp. nov.
Creators: name: Lowry, J. K.
name: Azman, B. A. R.
Publisher: name: Zenodo
Year: 2008
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Cyproideidae
Gbroidea
Gbroidea dingaalana

description: <i>Gbroidea dingaalana</i> sp. nov. (Figs 2–4) <b>Type material.</b> Holotype female, 2.5 mm, AM P76155, off Watsons Beach, Lizard Island, Queensland, Australia (14º40'S 145º28'E), living in association with the zygometrid crinoid, <i>Zygometra microdiscus</i> (Bell, 1882), 21 m, stn QLD 2010, R. T. Springthorpe, 10 February 1987. Paratypes: 2 females, AM P38471, stn QLD 2011; 4 females, AM P38472, off Watsons Beach, Lizard Island, Queensland, Australia (14º40'S 145º28'E), living in association with <i>Comathus briareus</i> (Bell, 1882), <i>Comatula rotalaria</i> Lamarck, 1816 and <i>Zygometra microdiscus</i> (Bell, 1882), 21 m, stn QLD 2011, R. T. Springthorpe, 10 February 1987; 4 females, AM P38473, stn QLD 2010. <b>Type locality.</b> Off Watsons Beach, Lizard Island, Queensland, Australia (14º40'S 145º28'E), living in association with the unstalked zygometrid crinoid, <i>Zygometra microdiscus</i> (Bell, 1882), 21 m. <b>Etymology.</b> The species name, <i>dingaalana</i>, is based on the aboriginal tribe that visited Lizard Island before it was occupied by Europeans. <b>Description</b>. Based on holotype female, 2.5 mm, AM P76155. <b>Head</b>. Lateral cephalic lobes apically acute. <i>Eyes</i> large, irregularly round with deep brown core. <i>Antenna 1</i> flagellum with about 4 articles each with long aesthetascs distally; accessory flagellum 1 articulate. <i>Antenna 2</i> slightly shorter than antenna 1, slender; flagellum with 4 articles, apex of terminal segment with few long setae. <i>Mandible</i> molar absent. <i>Maxilla 2</i> reduced. <i>Lower lip</i> outer lobes apically produced with dense short apical setae. <i>Maxilliped</i> inner and outer plates reduced; inner plate not broad, apically truncate; outer plate extending beyond inner plate, apex with one small robust seta and several simple setae; palp 4-articulate, article 2 wider than long, dactylus apically falcate. <b>Pereon</b>. <i>Gnathopod 1</i> coxa vestigial; basis robust, anterior margin with 4 medium length setae, posterior margin with 1 seta posterodistally; merus not elongated, posterior margin with two setae; carpus distally expanded, anterodistally rounded with a pair of setae, posterior margin slightly produced with 3 posterodistal setae; propodus subrectangular, anterior margin with 3 setae, tooth-like process anterodistally, posterior margin straight; dactylus falcate. <i>Gnathopod 2</i> basis robust, anterior margin lined with medium length setae, posterior margin without setae; merus posterodistal margin with long setae; carpus subtriangular, subequal in length with propodus, anterior margin without setae, anterodistal margin with two setae. <i>Pereopod 3</i> coxa anterior margin expanded, rounded, posterior margin slightly concave; basis anterior margin densely setose; merus gradually expanding anterodistally. <i>Pereopod 4</i> coxa enlarged, shield-like, anterior margin almost straight, posterior margin with well developed rounded posterodistal margin; basis anterior margin straight, posterior margin slightly concave. <i>Pereopod 5</i> coxa anterior and posterior margin rounded; basis slender, rectolinear; merus posterodistal margin slightly produced. <i>Pereopod 7</i> shorter than pereopod 6; coxa anteroventral margin produced, expanded; basis anterior margin straight, with 2 setae along margin, posterior margin expanded, with distal lobe extending beyond ischium. <b>Pleon</b>. <i>Epimeron 3</i> posterodistal margin rounded. <i>Uropod 1</i> rami subequal, peduncle slightly shorter than rami, both margins of both rami pectinate. <i>Uropod 2</i> biramous, inner ramus shorter than outer ramus, both margins of both rami pectinate. <i>Uropod 3</i> biramous; peduncle subequal in length of inner ramus; inner ramus shorter than outer, outer margins pectinate. <i>Telson</i> entire. <b>Male</b>. Unknown. <b>Colour.</b> Antennae, head, eye, pereon and coxae deep brown with a diffused white stripe between pereon and coxae and between coxae 3–4; gnathopods, pereopods, pleopods, uropods and urosome translucent. <b>Habitat</b>. Living in association with the crinoids, <i>Comathus briareus</i> (Bell, 1882), <i>Comatula rotalaria</i> Lamarck, 1816 and <i>Zygometra microdiscus</i> (Bell, 1882). <b>Remarks</b>. <i>Gbroidea dingaalana</i> is the only cyproideid amphipod currently known from the Great Barrier Reef. During a 1987 expedition to Lizard Island, M. Grygier, J. Lowry and R. Springthorpe examined 10 specimens of three crinoids: <i>Comathus briareus</i>, <i>Comatula rotalaria</i> and <i>Zygometra microdiscus</i>. There were 11 specimens of <i>G. dingaalana</i> living on these crinoids or about 1 amphipod per host. We suspect that <i>G.dingaalana</i> has evolved an obligate commensal relationship with unstalked crinoids or is possibly an epiparasite. <i>Comathus briareus</i> and <i>Comatula rotalaria</i> are both deep brown in colour and <i>Zygometra microdiscus</i> is deep purple. The deep brown camouflage colouration of <i>G. dingaalana</i> makes it undetectable on the crinoid hosts and by inference, less susceptible to predators. The weakly developed mouthparts of <i>G. dingaalana</i> indicate that it is probably feeding on sloughed mucous or soft tissue, possibly epidermal tissue from the crinoid, similar to the uristid amphipod, <i>Euonyx chelatus</i>, which is an epiparasite of the regular sea urchin, <i>Echinus esculentus</i> (see Vader 1978; Comely &amp; Ansell 1988). We only have information from three species of unstalked crinoids, but Messing <i>et al</i>. (2006) found 12 species of unstalked crinoids at Lizard Island. Interestingly Potts (1915) reported a purple amphilochid amphipod, <i>Cyclotelson purpureum</i>, associated with an unnamed crinoid, from Torres Strait. We did not find this species at Lizard Island. <b>Distribution</b>. <i>Australia</i>: Queensland: Lizard Island.
description: Published as part of <i>Lowry, J. K. &amp; Azman, B. A. R., 2008, A new genus and species of cyproideid amphipod associated with unstalked crinoids on the Great Barrier Reef, Australia, pp. 59-68 in Zootaxa 1760 (1)</i> on pages 61-65, DOI: 10.11646/zootaxa.1760.1.5, http://zenodo.org/record/5123724
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