Gnathostenetroides renbourni, Malyutina & L.Bruce, 2019

Malyutina, Marina V. & L. Bruce, Niel, 2019, 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, Zootaxa 4554 (2), pp. 301-350 : 319-326

publication ID	https://doi.org/ 10.11646/zootaxa.4554.2.1
publication LSID	lsid:zoobank.org:pub:24BF4E57-F9EA-440C-8D07-069A0756FBC0
DOI	https://doi.org/10.5281/zenodo.5923016
persistent identifier	https://treatment.plazi.org/id/78733D4B-FFDB-FF9A-8DC2-F8FB8539F806
treatment provided by	Plazi
scientific name	Gnathostenetroides renbourni
status	sp. nov.

Treatment

Gnathostenetroides renbourni View in CoL sp. nov.

( Figs 13–17 View FIGURE 13 View FIGURE 14 View FIGURE 15 View FIGURE 16 View FIGURE 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) GoogleMaps .

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 View FIGURE 13 ) 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 View FIGURE 13 , 15A View FIGURE 15 ) 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 View FIGURE 14 ): 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 View FIGURE 15 ) 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 View FIGURE 15 ) lateral endite width 2 mesial endite width, distally with 11 denticulate setae, setae length 0.70 endite width. Maxilla 2 ( Fig. 15E View FIGURE 15 ) 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 View FIGURE 15 ) 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 View FIGURE 16 ) 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.

Pereopod 2 ( Fig. 16D View FIGURE 16 , 17A View FIGURE 17 ) 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 View FIGURE 17 ) 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.

Pereopod 4 ( Fig. 17C View FIGURE 17 ) 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 View FIGURE 17 ) 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 View FIGURE 17 ) 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 View FIGURE 17 ) 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 View FIGURE 14 ) length 1.3 pleopod chamber length; pleopod length 1.50 width, distal margins rounded, with 9 – 11 setae each. Pleopod 2 ( Figs 14C View FIGURE 14 ) 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 View FIGURE 14 ) 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 View FIGURE 14 ) 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 View FIGURE 14 ) length 2.05 width.

Uropod ( Fig. 14B View FIGURE 14 ) 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 View FIGURE 16 ) 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 View FIGURE 14 ) 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 View FIGURE 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.