Quadrisegmentum lowryi Guerra-García, 2006

Guerra-García, José M. & Lowry, J. K., 2009, Caprellidae *, Zootaxa 2260 (1), pp. 290-327 : 321-323

Quadrisegmentum lowryi Guerra-García, 2006

( 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).

Figures

FIGURE 16. Quadrisegmentum lowryi Guerra-García, 2006. A, Holotype male, 6.2 mm, AM P61635, B, paratype female, 3.8 mm, AM P61636, C, premature female, inside the Outer Barrier, south-east of Cape York, Great Barrier Reef. Refigured from Guerra-García (2006).