The first record of Gnathostenetroididea Kussakin, 1967 from Australian waters with description of four new species of Gnathostenetroides Amar, 1957 (Crustacea: Isopoda: Asellota) from the Great Barrier Reef Author Malyutina, Marina V. Author L. Bruce, Niel text Zootaxa 2019 2019-02-11 4554 2 301 350 journal article 27574 10.11646/zootaxa.4554.2.1 f2fd53f0-4029-4df6-bd91-d9b2ea0fc8c2 1175-5326 2623588 24BF4E57-F9EA-440C-8D07-069A0756FBC0 Gnathostenetroides renbourni sp. nov. ( Figs 13–17 ) Material examined. All material Great Barrier Reef. Holotype : Terminal ♂ , ( 1.9 mm ), Heron Island—Wistari Reef channel, Capricorn Group, 23°27.248’S , 151°55.005’E , 25 November 2009 , small rubble, 29–30 m , CReefs stn HI09-106B, coll. K. Schnabel and S. Smith (MTQ W34282). Paratypes : Capricorn Group region : 1 ♂ , 4 ♀ , the same data as holotype (MTQ W34958) ; 3 specimens . same data as for the holotype, HI09-106B (MTQ W34281) . 2 specimens , Sykes Reef , 23.4316°S , 152.0493°E 14 November 2010 , sand, 27m , CReefs stn HI10-009F, coll. S. Smith (MTQ W33688) . Lizard Island region : 5 specimens , Yonge Reef, 14.60694°S , 145.62310°E , 20 April 2008 , back reef, dead coral heads 13 m , CReefs stn CGLI-047A, coll. M. Błażewicz-Paszkowycz (MTQ W31945). Etymology . Named for the late John Renbourn ( 1944–2015 ), an inspirational, brilliant and musically diverse British virtuoso guitarist. Description . Terminal male. Body ( Fig. 13A, B ) length 5.20 width, body height 0.10 of body length. Cephalon almost as long as wide, lateral margin with small seta anteriorly, rostrum 0.20 head length and 0.45 cephalon width. Eyes of 5 loose situated ommatidia. Pereonites lateral margin with 3 setae, anterolateral projections of pereonites 1 – 4 acute, distinctly protruded, distal stout UB seta long. Pereonite 4 length 0.55 pereonite 1 length. Posterior body part length 0.45 body length. Pereonite 7 length 1.65 pereonite 5 length. Pleotelson as long as wide, 0.20 body length; lateral margins to posterolateral indentation almost straight, posterior margin between indentations subtriangular, length 0.30 pleotelson length, lateral margin with 3 small setae and 5 long setae: two anterior, one middle and two in front of denticle; posterolateral margin with 4 long ventrolateral setae directed posteriorly and 3 long dorsolateral setae directed laterally, 4 setae posteriorly. Antennula ( Fig. 13C , 15A ) length 0.20 body length. Article 1 length 2.30 width, 0.70 as long as rostrum, distolaterally 1 broom seta, distomedially 2 simple setae; length ratios of articles 2–5 to article 1: 0.65, 0.50, 0.55, 0.50. Article 2 distomedially with 1 long broom seta and 2 long spine-like setae, distolaterally with 2 long broom setae; article 3 distolaterally with 1 simple seta medially and 3 setae laterally; article 4 with 1 simple short distomedial seta, article 5 with tuft of 4 long simple distal setae and 3 aesthetascs. Antenna ( Fig. 14A ): antenna length 0.75 body length, peduncle articles 1 – 4 not reaching tip of antennula article 3. Article 3 scale with 3 distoventral setae. Article 4 with 2 small distal setae. Article 5 length 1.50 articles 1 – 4 total length; article 6 length 1.35 article 5 length, with scattered long setae, length together 0.55 body length. Flagellum of 17 articles, first article about 3 times longer than following articles, each article with 2 small distal setae. Mandible ( Fig. 15B, C ) pars incisiva with 5 cusps; lacinia mobilis of left mandible broadening distally, not reaching tip of pars incisiva , with 6 teeth; spine row with 8 and 10 spines on left and right mandibles respectively; molar process with 2 distal setae, length 0.65 pars incisive length. Palp length 0.90 mandibular body length, article 1 with 2 long distal setae. Article 2 length 1.90 article 1 length, with 3 short setae and 2 long distally serrated setae on distolateral half. Article 3 with rows of short cleaning setae on distal half and 1 long distal seta. Maxilla 1 ( Fig. 15D ) lateral endite width 2 mesial endite width, distally with 11 denticulate setae, setae length 0.70 endite width. Maxilla 2 ( Fig. 15E ) lateral and middle endite subequal in length, with 4 long distal setae each; mesial endite shortest, as wide as middle and lateral endites together, with numerous distal setae and distomedially few comblike setae. Maxilliped ( Fig. 15F ) basis length 4.40 width, endite length 1.50 width, with 3 coupling hooks, distal margin slightly concave, with 5 broad fan-like setae and numerous simple slender setae. Palp 0.50 as long and 0.70 as wide as basis and inserted after 0.50 basis length, article 2 as long as wide, medial margin length 1.25 lateral margin length, medial margin with 4 whip setae; articles 3 – 5 subequal in length as long as article 2 laterally, article 3 medial margin length 0.80 medial length of article 2, with 6 long setae; article 4 with 5 long distal setae; article 5 slender, with 4 long distal setae. Epipod length 4 width and 0.80 basis length. Pereopod 1 ( Fig. 16C ) length 0.45 body length, length ratios of ischium–dactylus to basis: 0.5, 0.45, 0.30, 1.15, 0.75. Basis length 2.40 width, with 1 distoventral seta. Ischium length 1.25 width, with 3 dorsal setae. Merus length 0.5 width, dorsal projection with 5 strong marginal setae, ventral margin with 6 setae. Carpus length 0.70 width, with 9 ventral long setae. Propodal palm subrectangular, length 1.60 width, ventral margin convex proximally, length 0.55 dorsal margin length, with dense row of about 20 long strong setae, distoventral spine-like UB seta length 0.45 anterior margin length, anterior margin with 6 slender plumose setae, length Ẽ 0.70 spine-like seta length; dactylus with claw length 5.50 width, ventral (inner) margin with 6 slender short setae, claw length 0.20 dactylus length, small serrated seta ventrally, one long slender seta in between, 2 whip setae proximally to claw, two long setae ventrally to claw. Length ratios of pereopods 2–7 to pereopod 1: 0.75, 0.60, 0.60, 0.70, 0.75, 0.75. FIGURE 13. Gnathostenetroides renbourni sp. nov. : male (1.9 mm), holotype MTQ W34282: A, dorsal view; B, lateral view; C, antennula; D, uropod. FIGURE 14. Gnathostenetroides renbourni sp. nov. : male (2.1 mm), paratype MTQ W34281: A, lateral view; B, pleotelson ventral view; C, pleopod 2; D, penis. Female, paratype MTQ W34281: E, pleopod 3; F, pleopods 4 and 5; G, pleopod 2. FIGURE 15. Gnathostenetroides renbourni sp. nov. : male (1.5 mm), holotype MTQ W34282: A, head, dorsal view; B, right mandible; C, left mandible; D, maxilla 1; E, maxilla 2; F, maxilliped. FIGURE 16. Gnathostenetroides renbourni sp. nov. : female paratype MTQ W34281: A, pereopod 1; B, pereopod 2; male (1.9 mm), holotype MTQ W34282: C, pereopod 1; D, pereopod 2. Pereopod 2 ( Fig. 16D , 17A ) length 0.77 pereopod 1 length, length ratios of ischium–dactylus to basis: 0.70, 0.40, 0.75, 0.80, 0.30; basis length 2.30 width, dorsal margin with 2 small setae and 1 distoventral seta, ischium length 2.70 width, with 1 strong dorsal seta; merus length 1.70 width, with 1 distoventral simple seta and 1 strong distodorsal seta; carpus length 3.90 width, with 3 ventral setae and 1 small distodorsal seta; propodus length 5.30 width, with 5 stout ventral whip setae and 1 distoventral UB seta, 3 simple setae dorsally; dactylus claws length 0.30 total length, 3 setae midlength, 1 seta between claws. Pereopod 3 ( Fig. 17B ) length ratios of ischium–dactylus to basis: 0.65, 0.35, 0.75, 0.80, 0.30; basis length 2.80 width, dorsal margin with 2 small setae; ischium length 2.65 width, with 1 stout dorsal seta and 1 small ventral seta; merus length 1.70 width, with 2 distoventral and 4 small dorsal setae; carpus length 3.80 width, with 3 whip ventral and 1 small distodorsal seta; propodus length 5 width, with 4 ventral whip setae, 1 stout UB distoventral seta and 2 dorsal simple setae; dactylus length 2.20 width, with 1 serrated small ventral seta, claw length 0.50 dactylus length. FIGURE 17. Gnathostenetroides renbourni sp. nov. : male, holotype MTQ W34282: A–F, pereopods 2–7. Pereopod 4 ( Fig. 17C ) shortest, 0.6 pereopod 1 length, length ratios of ischium–propodus to basis: 0.65, 0.45, 0.85, 0.95; 0.35; basis length 2.40 width, with 2 dorsal simple setae; ischium length 2.20 width, 2 dorsal and 2 ventral setae; merus length 1.65 width, with 1 distoventral and 1 distodorsal setae; carpus length 4.15 width, with 3 ventral whip setae and 2 dorsal simple setae; propodus length 6.60 width, with 6 ventral and 2 dorsal simple setae; dactylus length 2.20 width with 1 serrated small ventral seta. Pereopod 5 ( Fig. 17D ) length ratios of ischium–dactylus to basis: 0.65, 0.35, 0.75, 0.80, 0.30; basis length 2.40 width, with 2 dorsal setae; ischium length 2.70 width, with 3 dorsal setae; merus length 1.25 width, with 1 distodorsal seta and 1 distoventral seta; carpus length 3.10 width, with 2 distodorsal and 2 ventral setae; propodus length 4.0 width with 4 long whip ventral setae and 1 distoventral UB and 2 distodorsal small setae; dactylus length 2.50 width, claw length 0.40 dactylus total length, ventral claw broader than dorsal claw. Pereopod 6 ( Fig. 17E ) length ratios of ischium–dactylus to basis: 0.65, 0.40, 0.75, 0.95, 0.30; basis length 2.50 width, with 2 dorsal and 2 ventral setae; ischium length 2.90 width, with 2 strong and 1 small dorsal setae and 2 small ventral setae; merus length 1.4 width with 1 distoventral and 1 distodorsal setae; carpus length 2.70 width, with 3 ventral and 2 distodorsal simple setae; propodus length 4.40 width, with 3 long whip ventral setae, 1 UB distoventral seta and 3 distodorsal small setae; dactylus of same size. Pereopod 7 ( Fig. 17F ) length ratios of ischium–dactylus to basis: 0.70, 0.35, 0.70, 0.70, 0.25; basis length 2.60 width, with 1 dorsal and 3 ventral simple setae; ischium length 2.75 width, with 1 whip dorsal seta and 3 small ventral setae; merus length 1.70 width, with 1 distoventral and 1 distodorsal setae; carpus length 3.3 width, with 2 ventral and 2 distodorsal setae; propodus length 3.50 width, with 3 long whip ventral setae, 1 distoventral UB seta and 2 distodorsal small setae; dactylus length 2.60 width. Pleopod 1 ( Figs 14B ) length 1.3 pleopod chamber length; pleopod length 1.50 width, distal margins rounded, with 9 – 11 setae each. Pleopod 2 ( Figs 14C ) protopod length 1.65 width, 0.35 pleopod 1 length, lateral margin without setae, endopod article 1 length 0.50 protopod length, article 2 length 0.70 protopod length, exopod length 1.35 width, 0.20 protopod length. Pleopod 3 ( Figs 14E ) protopod length 0.90 width, endopod length 1.85 width, distal plumose setae 0.50 endopod length, position: 1 distomedial seta separated from 2 distolateral setae closely located to each other; exopod length 6.90 width, 1.60 endopod length and 0.45 endopod width, article 1 with 3 slender setae laterally, distal article separated, length 0.40 basal article length, with two distal setae. Pleopod 4 ( Figs 14F ) endopod length 1.80 width, exopod length 0.65 endopod length, width 0.30 endopod width, 2 simple fine setae laterally. Pleopod 5 ( Figs 14F ) length 2.05 width. Uropod ( Fig. 14B ) 0.6 pleotelson length. Protopod length 1.55 width, lateral margin with 3 distal setae, medial margin slightly convex with 2 – 3 setae; 5 setae distally; endopod length 6 width and 1.90 protopod length, with 3 medial setae and 6 simple long and 1 – 2 broom setae distally; exopod length 6.0 width, 0.60 endopod length, with 5 – 6 long distal setae. Female largely similar to male, differences: Pereopod 1 ( Fig. 16A ) length 0.3 body length, length ratios of ischium–dactylus to basis: 0.50, 0.50, 0.30, 1.0, 0.70. Basis length 2.65 width. Ischium length 1.20 width, with 1 small and 1 stout dorsal setae. Merus length 0.90 width, with 3 dorsal setae, distodorsal projection terminating with spine-like seta. Carpus length 0.80 width, with row of ventral long setae. Propodal palm length 1.70 width, ventral margin length 0.70 dorsal margin length, ventral margin with 13 stout long setae, distoventral spine-like UB seta length 0.60 anterior margin width, anterior margin with 4 comb-like long setae and 4 slender simple setae. Dactylus together with claw length 6.0 width, claw length 0.40 total length. Dactylus ventral (inner) margin with 5 stout short setae, 3 long whip setae proximally to claw, two long slender setae ventrally to claw. Pleopod 2 ( Fig. 14G ) length 1.35 width, distal margin rounded, lateral and distal margins fringed with 7 long setae each, 1 small simple seta laterally, indentation length 0.05 pleopod length. Remarks . Gnathostenetroides renbourni sp. nov . can be identified by the following characters: propodal palm broad in both sexes (L/W 1.60 – 1.70), differing from other species that have a broad palm by the subrectangular shape of the palm with a proximally convex ventral margin in males ( Fig. 33 ); the merus has the distodorsal lobe as broad as article itself. The palm is similar to that of G. polynesica , but has a proximal projection on ventral margin and the denticulate anterior margin that is lacking in G. polynesica Müller, 1992 . G. renbourni sp. nov . differs from G. blazewiczae sp. nov . which has a similarly elongate body of similar proportions by having a broader and longer rostrum and eyes with more widely spaced ommatidia. Distribution . Southern Great Barrier Reef, Capricorn–Bunker Group at the Heron Island–Wistari Reef channel and Sykes Reef; northern Great Barrier Reef, Lizard Island region at Yonge Reef; at depths from 13 to 30 metres.