Joeropsis varanus, Bruce, Niel L., 2015

Bruce, Niel L., 2015, Joeropsididae Nordenstam, 1933 (Crustacea, Isopoda, Asellota) from the Lizard Island region of the Great Barrier Reef, Queensland, Australia, ZooKeys 491, pp. 1-62 : 42-45

Taxon classification Animalia Isopoda Joeropsididae

Joeropsis varanus sp. n. Figs 25, 26, 27

Material.

Holotype. ♂ (3.0 mm), North Point, Lizard Island, 14.64553°S, 145.45335°E, 12 April 2008, compacted dead Acropora , 0.5 m, stn CGLI-20C, coll. NLB (MTQ W31921).

Paratypes. ♂ (2.0 mm; dissected, two slides), Seabird Islet, Lizard Island, 14.69497°S, 145.4657°E, 23 February 2009, outer reef front, dead coral heads, 6-8 m, stn LIZ09-19B, coll. MB-P & NLB (MTQ W31923). Juv. (1.3 mm), same data as holotype (MTQ W13976). Juv. (1.8 mm), same data as holotype (MTQ W31922).

Description.

Body 3.1 as long as greatest width, dorsal surfaces smooth, without setae. Cephalon length 0.6 width, lateral margins evenly weakly convex, strongly serrate (anterior 4 teeth prominent). Pseudorostrum 0.6 as long as proximal width, anterior margin acute. Eyes sublateral, with ~18 ommatidia, colour dark brown. Pereonites compact, close to each other, without dorsal carinae; tergite lateral margin subtruncate, lateral margins smooth; median keels not observed. Pleotelson width 1.3 length; dorsal surface with single median and paired submedian low ridges, caudomedial lobe narrowly rounded; lateral margins convex, each with 8 spines (prominent).

Antenna 1 with 5 articles; article 1 1.2 as long as wide, distolateral angle not lobed, with serrations, distomesial margin not serrate; article 2 0.5 as long as article 1, 1.3 as long as wide; lateral margins of articles 1 and 2 without cuticular scales; article 3 0.6 as long as article 2; article 4 0.7 as long as article 3; article 5 1.2 as long as article 3, 2.0 as long as proximal width, distally with 2 aesthetascs (and 2 simple setae). Antenna 2 peduncle article 5 1.3 as long as articles 1-4 combined, 4.3 as long as article 3, 1.8 as long as wide, lateral margin weakly convex, distally concave, with small cuticular scales, mesial margin weakly convex; article 6 1.2 as long as width, distally weakly expanded, distal width 1.8 proximal width, 0.5 as long as article 5, lateral margin without cuticular scales, mesial margin with 2 simple setae, distodorsal surface without setae; flagellum with 5 articles, article 1 0.8 as long as peduncle article 6, 1.2 as long as combined lengths of remaining articles.

Mandible palp article 2 not observed. Right incisor with symmetrical cusps, margins convex, distally acute; left mandible incisor similar to right incisor. Molar process entirely smooth. Right mandible spine row composed of 8 spines; left mandible spine row composed of 9 spines, not divided by truncate lobe; without lacinoid spine. Maxilla 1 lateral lobe with 12 strongly serrate RS, and 2 simple RS; mesial lobe with 3 long, simple RS. Maxilla 2 lateral lobe with 4 long, curved, finely serrate setae; middle lobe with 4 long serrate setae, mesial lobe with 1 serrate and 3 long simple setae and many long setules. Maxilliped endite 2.1 as long as greatest width, extending to middle of palp article 4, distal margin evenly rounded, finely serrate (laterally), with shallow distomesial concavity, with 3 mesial tubercular RS (plus 1 triangular RS and one serrate RS at distomesial angle), distomesial margin with 4 coupling setae. Maxilliped palp article 2 2.6 as long as article 1, mesial lobe extending to mid-margin of article 3, distomesial margin with 3 simple setae; article 3 0.5 as long as article 2, distomesial margin with 1 simple seta; article 4 4.2 as long as wide, mesial margin straight, distally with 3 setae; article 5 0.2 as long as 4, with 5 terminal setae.

Pereopod 1 basis 3.2 as long as wide, superior margin with 1 simple seta; ischium 0.8 as long as basis, 3.1 as long as wide (superior margin with 3 stiff setae); merus 0.5 length of ischium, 1.8 as long as wide; carpus 1.1 as long as ischium, 5 as long as wide (inferior margin with 3 long stiff setae); propodus 5.2 as long as wide, superior margin 3 simple setae (and prominent penicillate seta at distal angle); inferior margin with 3 acute RS (distal three-quarters with cuticular scale-setae), dactylus 0.4 as long as propodus, with 2 claws. Pereopods 2-7 sub-similar, more slender than pereopod 1, each with 3 claws. Pereopod 7 basis 3.7 as long as wide; superior margin with 1 short simple seta, inferior margin with 3 simple setae; ischium 0.7 as long as basis, 3 as long as wide, superior margin weakly convex at midpoint, with 2 simple setae, inferior distal margin with 1 seta; merus 0.7 as long as ischium, 1.7 as long as wide, superodistal angle with 2 simple setae, inferior margin with 2 simple setae; carpus 1.1 as long as ischium, 4.4 as long as wide, inferior margin with 5 simple setae, superior margin with 1 simples seta, distal angle with 1 prominent pappose seta; propodus 1.1 as long as ischium (1.13), 5.8 as long as wide, inferior margin with 3 acute RS, superior margin with 4 simple setae; dactylus 0.5 as long as propodus.

Pleopod 1 1.9 as long as greatest width, lateral margin weakly concave, apical lobe narrowly rounded with strongly oblique mesial margin, with long marginal setae, lateral margin with slender setae, distolateral lobe acute, not extending to distal margin. Pleopod 2 protopod 2.7 as long as midwidth, lateral margin mid-half weakly convex, without setae, distal margin weakly concave, with long marginal scales, apex narrowly rounded; stylet in retracted position reaching apex. Pleopod 3 endopod 2.6 midwidth; exopod article 1 4.4 as long as wide, extending beyond apex, lateral margin densely fringed with cuticular scale-setae; article 2 0.4 as long as article 1, lateral and mesial margins with long cuticular scale-setae (lateral only).

Uropod peduncle extending slightly beyond margin of pleotelson, mediodistal corner strongly produced and acute, distolateral margin with 2 simple submarginal setae, mesial margin serrate. Exopod 0.5 as wide as endopod, 1.2 as long as wide, with 5 simple setae. Endopod 0.9 as long as wide, 0.3 as long as peduncle proximolateral margin, apex with 8 long simple setae.

Female. No females present in material.

Colour pattern.

Head with narrow, brown band running between the eyes and to lateral margin, occupying 30% of head length. Pereonites and pleotelson clear in holotype, in smaller male paratype tergite lateral margin of pereonite 2 with chromatophores; in the juvenile (MTQ W31922) tergite lateral margin of pereonites 2, 4, 6, 7 and anterior of pleotelson with chromatophores.

Size.

Adult males 2.0-3.0 mm.

Remarks.

Joeropsis varanus sp. n. may be identified by the short interocular head band, lateral margins of the head with strong serrations, pleotelson lateral margin with eight serrations and an acute pseudorostrum. The pereopods of Joeropsis varanus are more slender than in many other species.

Distribution.

Fringing reef at North Point and Seabird Islet, Lizard Island (Fig. 1); intertidal to 8 metres.

Etymology.

The epithet is the genus name for the Sand Monitor, Varanus gouldi , from which Lizard Island got its English name.