Elaphognathia queenslandica, Svavarsson & Bruce, 2019

Svavarsson, Jörundur & Bruce, Niel L., 2019, New gnathiid isopod crustaceans (Cymothoida) from Heron Island and Wistari Reef, southern Great Barrier Reef, Zootaxa 4609 (1), pp. 31-67 : 32-37

Elaphognathia queenslandica sp. nov.

(Figs 1–4)

Material examined. Holotype . ♂ (1.7 mm), Heron Island , 23.4445°S, 151.9114°E, 8 January 1979, mid reef flat in dead coral, coll. N.L. Bruce (MTQ W10690).

Paratypes. ♂ (1.8 mm, dissected, 7 microslides), Heron Island, ‘Blue Pools’, 23.4354°S 151.9224°E, 17 January 1979, intertidal boulder zone, coll. N.L. Bruce (MTQ W10691). ♂ (1.6 mm), Heron Island, 14 January 1979, outer reef flat, from dead coral, coll. N.L. Bruce (MTQ W10692). 2 ♂ (1.7, 1.8 mm), Lamont Reef, 23°35.671’S, 152°03.855’E, 19 November 2009, coral rubble, southern side, 11.5 m, CReefs stn HI09-059A, coll. K. Schnabel and N.L. Bruce (MTQ W31664). ♂ (1.8 mm), Lamont Reef, 23°35.671’S, 152°03.855’E, 19 November 2009, Acropora rubble, northern side, base of live Acropora bank near reef crest, 10.5 m, CReefs stn HI09-059C, coll. K. Schnabel and N.L. Bruce (MTQ 31665).

Description. Body (Fig. 1A) 2.4 times as long as greatest width, widest at pereonite 3 and pereonite 4; dorsal surfaces polished, without setae. Cephalosome (Fig. 1B–E) quadrate, 0.7 times as long as wide, lateral margins convex; dorsal surface smooth; dorsal sulcus wide, deep, short; translucent region absent; paraocular ornamentation ab-

Antennula ( Fig. 2A ) article 3 1.8 times as long as article 2, 2.5 times as long as wide; flagellum 0.8 times as long as article 3, with 3 articles. Antenna ( Fig. 2B ) peduncle article 4 1.2 times as long as wide, 1.3 times as long as article 3, with 2 penicillate setae, and 1 simple setae; article 5 1.9 times as long as article 4, 2.6 times as long as wide, inferior margin with 2 penicillate setae, with 4 simple setae; flagellum as long as article 5, with 7 articles.

Mandible (Fig. 1B–E, 2A) 0.5 times as long as width of cephalosome, mandible oval, weakly curved, distally; mandible apex 8 % total length; mandibular seta present. Carina present, smooth. Incisor knob-like, distal denticulation present. Blade present, dentate, unevenly convex, distally convex, dentate along 40 % of margin. Pseudoblade absent; internal lobe present, rounded, large, smooth; dorsal lobe absent; basal neck short; erisma present; lamina dentata absent.

Maxilliped ( Fig. 2C ) 5-articled. Maxilliped article 1 lateral margin with continuous marginal scale-setae; article 2 lateral margin with 4 plumose setae; article 3 lateral margin with 4 plumose setae; article 4 lateral margin with 5 plumose setae; article 5 with 8 plumose setae; endite extending to distal margin of article 2; without coupling setae. Pylopod ( Fig. 2D ) article 1 1.3 times as long as wide, without distolateral lobe; posterior and lateral margins forming rounded curve; lateral margin with 17 large PMS (one missing in illustrations); mesial margin with continuous scale-setae, distal margin with 2 simple setae; article 2 ( Fig. 2E ) 1.3 times as long as wide; article 3 absent.

Pereopods 2–6 without long plumose setae; propodus distal RS 1.5 times length of proximal RS; lateral and inferior margins with prominent tubercles, pereopod 2 with weak tubercles on merus and carpus. Pereopod 2 ( Fig. 3A ) basis 2.1 times as long as greatest width, superior margin with 4 setae, inferior margin with 4 setae; ischium 0.6 times as long as basis, 1.5 times as long as wide, superior margin with 3 setae, inferior margin with 6 setae; merus 0.4 as long as ischium, 0.7 as long as wide, superior margin distally with 3 setae (one biserrate), inferior margin with 6 setae; carpus 0.6 times as long as ischium, 1.5 times as long as wide, superior margin with 2 setae, inferior margin with 3 setae (one biserrate); propodus ( Fig. 3B ) 0.8 times as long as ischium, 2.8 times as long as wide, superior margin with 2 setae, inferior margin with 2 simple setae and 2 RS; dactylus ( Fig. 3B ) 0.6 times as long as propodus. Pereopods 3 and 4 similar to pereopod 2. Pereopod 5 similar to pereopod 6. Pereopod 6 ( Fig. 3C ) with weak tubercles on ischium to carpus, basis 2.4 times as long as greatest width, superior margin with 1 simple seta and 3 penicillate setae, inferior margin with 4 setae; ischium 0.7 times as long as basis, 1.8 times as long as greatest width, superior margin with 2 setae, inferior margin with 2 setae; merus 0.5 times as long as ischium, 1.3 times as long as wide, superior margin with 3 setae (two biserrate), inferior margin with 3 setae, without dense patch of scale-setae; carpus 0.4 times as long as ischium, 1.4 times as long as wide, superior margin with 1 seta, inferior margin with 2 setae; propodus ( Fig. 3D ) 0.7 times as long as ischium, 3.1 times as long as wide, superior margin with 3 setae, inferior margin with 2 setae, and 2 RS; dactylus ( Fig. 3D ) 0.6 times as long as propodus. Penes opening flush with surface of sternite 7.

Pleotelson ( Fig. 4B ) 0.9 times as long as anterior width, lateral margins smooth, anterolateral margins weakly convex, posterolateral margin straight; posterolateral margin with 4 submarginal setae, apex with 2 setae.

Pleopod 2 ( Fig. 4A ) exopod 2.2 times as long as wide, with 9 PMS; endopod 1.9 times as long as wide, with 8 PMS. Pleopod 2 appendix masculina absent.

Uropod ( Fig. 4B ) rami extending beyond pleotelson, apices broadly rounded. Peduncle with 1 dorsal seta. Endopod 2.2 times as long as greatest width, dorsally with 6 sensory setae; lateral margin proximally convex, distally straight, lateral margin with 1 simple seta; mesial margin strongly convex, with 6 long plumose setae. Exopod not extending to end of endopod, 3.1 times as long as greatest width; lateral margin straight, with 6 simple setae; proximomesial margin straight, mesiodistal margin with 4 long PMS.

Remarks. Elaphognathia queenslandica sp. nov. is most similar to Elaphognathia forceps Holdich & Harrison, 1980 and Elaphognathia australis Svavarsson & Bruce, 2012 , both species occurring in Australia. It differs from E. forceps in the shape of the excavation of the frontal margin, being narrow and deep in E. forceps ( Holdich & Harrison 1980) . The species differs from E. australis in having the mediofrontal process rounded, being strong and acute in E. australis ( Svavarsson & Bruce 2012) .

Etymology. The name refers to the region of Australia where the species was collected, i.e. Queensland.

Distribution. Heron Island, southern Great Barrier Reef; intertidal to 10.5 m.

Figures

FIGURE 2. Elaphognathia queenslandica sp. nov., ♂, paratype, 1.8 mm (MTQ W10691). A, mandible and antennula in situ, dorsal view, left side. B, antenna in situ. C, maxilliped. D, pylopod. E, second article of pylopod.

FIGURE 3. Elaphognathia queenslandica sp. nov., ♂, paratype, 1.8 mm (MTQ W10691). A, pereopod 2. B, propodus and dactylus of pereopod 2. C, pereopod 6. D, propodus and dactylus of pereopod 6.

FIGURE 4. Elaphognathia queenslandica sp. nov., ♂, paratype, 1.8 mm (MTQ W10691). A, pleopod 2. B, pleotelson and uropod.