Gbroidea dingaalana Lowry & Azman, 2008

Azman, B. A. R., 2009, Cyproideidae *, Zootaxa 2260 (1), pp. 380-392 : 385-388

Gbroidea dingaalana Lowry & Azman, 2008

( Figs 4 , 5 , Pl. 2H)

Gbroidea dingaalana Lowry & Azman, 2008: 61 , figs 2–4.

Type locality. Off Watsons Beach , Lizard Island, Queensland, Australia (14º40’S 145º28’E) .

Material examined. Holotype female, 2.5 mm, AM P76155 (QLD 2010). Paratypes : 4 females, AM P38473 (QLD 2010) ; 2 females, AM P38471(QLD 2011) ; 4 females, AM P38472 (QLD 2011) .

Description. Based on holotype female, 2.5 mm, AM P76155.

Head. Head lateral cephalic lobes apically acute. Eyes large, irregularly round with deep brown core. Antenna 1 flagellum with about 4 articles each with long aesthetascs distally; accessory flagellum 1 articulate. Antenna 2 slightly shorter than antenna 1, slender; flagellum with 4 articles, apex of terminal segment with few long setae. Lower lip outer lobes apically produced with dense short apical setae. Maxilliped 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.

Pereon. Gnathopod 1 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. Gnathopod 2 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. Pereopod 3 coxa anterior margin expanded, rounded, posterior margin slightly concave; basis anterior margin densely setose; merus gradually expanding anterodistally. Pereopod 4 coxa enlarged, shield-like, anterior margin almost straight, posterior margin with well developed rounded posterodistal margin; basis anterior margin straight, posterior margin slightly concave. Pereopod 5 coxa anterior and posterior margin rounded; basis slender, rectolinear; merus posterodistal margin slightly produced. Pereopod 7 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.

Pleon. Epimeron 3 posterodistal margin rounded. Uropod 1 rami subequal, peduncle slightly shorter than rami, both margins of both rami pectinate. Uropod 2 biramous, inner ramus shorter than outer ramus, both margins of both rami pectinate. Uropod 3 biramous; peduncle subequal in length of inner ramus; inner ramus shorter than outer, outer margins pectinate. Telson entire.

Male (sexually dimorphic characters). Unknown.

Habitat. Living in association with the unstalked crinoids, Comathus briareus, Comatula rotalaria and Zygometra microdiscus .

Remarks. As Lowry & Azman (2008) pointed out, Gbroidea dingaalana has been observed on three crinoid species: Comathus briareus, Comatula rotalaria and Zygometra microdiscus . The weakly developed mouthparts of G. dingaalana indicate that it is probably feeding on soft tissue, possibly epidermal tissue from the crinoid. This relationship appears to be very similar to that mentioned by Vader (1978) and Comely & Ansell (1988) for the uristid amphipod, Euonyx chelatus , which is an epiparasite of the regular sea urchin, Echinus esculentus .

Morphologically Gbroidea dingaalana appears to be most closely related to the genera Cyproidea and Mokuoloe by having similar shape and embellishment especially the rectolinear basis of pereopod 5 to 6, however both of the genera differ from the present species by having subchelate gnathopod 1. Ultimately Gbroidea dingaalana has no agreement with any other species shown in its unique association with the three crinoid species, apart from that it is easily distinguished by the, (1) absence of molar, (2) gnathopod 1-2 simple, (3) pereopod 5-6 basis rectolinear, (4) urosomite 1 elongate, without dorsal keel, (5) urosomite 3 not projecting over telson, (6) telson laminar, shorter than apex of uropod 3 rami.

Distribution. Australia. Queensland: Lizard Island ( Lowry & Azman 2008).

Figures

FIGURE 4. Gbroidea dingaalana Lowry & Azman, 2008, holotype, female, 2.5 mm, AM P76155, off Watsons Beach, Lizard Island, Great Barrier Reef (after Lowry & Azman 2008).

FIGURE 5. Gbroidea dingaalana Lowry & Azman, 2008, holotype, 2.5 mm, AM P76155, off Watsons Beach, Lizard Island, Great Barrier Reef (after Lowry & Azman 2008).