(Fig. 16)

Quadrisegmentum lowryi Guerra-García, 2006: 437, figs 34–38.

Material examined. Holotype male, 6.2 mm, AM P61635 (QLD 674). Paratypes: 1 female, AM P61636 (QLD 674). See station list for occurrences (Lowry & Myers 2009) and Guerra-García (2006) for complete material examined.

Type locality. Inside the Outer Barrier, south-east of Cape York, Queensland (10º56.90’S 144º 0.51’E), coral rubble, 20 m depth (QLD 674).

Description. Based on holotype male, 6.2 mm, AM P61635 paratype female, 3.8 mm, AM P61636.

Head and pereonites slender. Head/pereonite 1 fused (suture absent) concave along dorsal margin or dorsal margin straight; eye large, distinctive. Antenna 1 well developed; slender, as long or longer than body; peduncle articles 2 and 3 subequal in length, article 3 straight; accessory flagellum absent; flagellum subequal in length to peduncle, with more than 2 articles. Antenna 2 0.5 x antenna 1 length, slender; peduncle without setae; flagellum 0.75 x peduncular length, with more than 4 articles. Labrum notched, forming rounded quadrilateral projections (very rounded). Mandible right incisor with 5 teeth, right lacinia mobilis absent, three plates accessory setal row with 3 setae; molar absent; left incisor with 5 teeth, lacinia mobilis with 4 teeth, with 3 trapezoid plates decreasing in size, accessory setal row with three setae; palp 3–articulate, palp setal formula 1-0-1. Maxilla 1 outer plate with 6 stout apical setal-teeth. Maxilliped inner plate larger than outer plate; subrectangular; outer plate 2/3 (0.66 x) length of inner plate; palp article 2 scarcely setose on inner margin; palp article 4 not enlarged, falcate.

Pereon. Pereonites 2 to 7 not fused; pereonite 5 longest. Pereonite 1 without projections. Gnathopod 1 distinctly smaller than gnathopod 2; propodus subtriangular, palm begins 2/5 along posterior margin, smooth, without large, rounded knob proximally; dactylus slightly curved, inner margin smooth. Pereonite 2 with small mid-dorsal hump. Gnathopod 2 situated toward anterior end of pereonite 2; basis greater than 2 x length of pereonite 2, without anterodistal projection; ischium without anterodistal projection; propodus subovate, massive, anterodistal margin straight, without anterodistal triangular projection, without projections along mid-anterior margin; palm with proximal cavity filled with a membranous sack, palm proximal projection with 1 robust (grasping) seta, palm margin straight or irregular (slightly), smooth, without hook-like projection at base of dactylus, without distal shelf, without sinus, without midpalmar projection. Pereonite 3 without projections. Pereopod 3 well developed, with 6 articles. Pereonite 4 without projections. Pereopod 4 well developed, with 6 articles. Pereopod 5 reduced or vestigial, with 4 slender articles. Pereopods 6 and 7 simple. Pereopod 6 basis longest followed by merus. Pereopod 7 similar to pereopod 6.

Gills on pereonites 2 to 4. Pereonite 2 gill triangular, pereonite 3 gill length about 1/3 of corresponding pereonite, straight, elongate, cylindrical. Pereonite 4 gill length about 1/3 of corresponding pereonite, straight, elongate, cylindrical.

Pleon. Uropod 1 present. Uropod 2 ramus well developed.

Female (sexually dimorphic characters). Antenna 1 flagellum 7–articulate; Antenna 2 flagellum 3– articulate. Gnathopod 2 carpus about 3 x as long as wide, more elongate than in male, with 3 robust (grasping) setae and without membranous sack proximally. Pereopods 6 and 7 6–articulate, propodus with 4 robust (grasping) setae and 1 seta on pereopod 6 and 3 robust (grasping) setae and 1 seta on pereopod 7. Oostegites not setose.

Habitat. Coral rubble, 8 to 20 m depth.

Remarks. Quadrisegmentum lowryi is very similar to its only congener Q. triangulum. The main differences between the two species are: (1) the antennae, gnathopods and pereopods 6 and 7 are clearly longer in Q. lowryi; (2) the propodus of the gnathopod 2 male is provided with a developed distal triangular projection in Q. triangulum while this projection is absent in Q. lowryi; (3) the abdominal appendages are 2– articulate in Q. triangulum and 1–articulate in Q. lowryi.

Besides these differences, the membranous sack present on the male propodus palm of Q. lowryi is apparently not present in Q. triangulum (Hirayama, 1988).

Distribution. Australia. Queensland: south-east of Cape York and Palfrey and South Islands, Lizard Island (Guerra-García 2006).