Orthoprotella pearce Guerra-García, 2006

Guerra-García, José M. & Lowry, J. K., 2009, Caprellidae *, Zootaxa 2260 (1), pp. 290-327 : 301-302

Orthoprotella pearce Guerra-García, 2006

( Fig. 6 )

Orthoprotella pearce Guerra-García, 2006: 445 , figs 47–51. Material examined. Holotype male, 5.6 mm, AM P61740 ( QLD 1580 ). Paratype: 1 female, 5.4 mm, AM P61741 ( QLD 1580 ) .

Type locality. Pidgin Point , Watsons Bay, Lizard Island, Queensland, Australia (14°41’S 145°27’E), on the hydroid Halopteris buskii , 5–10 m.

Description. Based on holotype male, 5.6 mm and paratype female, 5.4 mm.

Head and pereonites slender. Head/pereonite 1 fused (suture present), dorsal margin convex; eye large, distinctive. Antenna 1 well developed; slender, 0.67 x body length; peduncle article 2 longest, article 3 straight; accessory flagellum absent; flagellum slightly longer than peduncle, with more than 2 articles, proximal article composed of 2 articles. Antenna 2 0.5 x antenna 1 length, slender; peduncle with several feeble setae; flagellum about 1/4 (0.25 x) of peduncular length, with 2 articles. Labrum weakly notched, forming rounded quadrilateral projections. Mandible right incisor with 5 teeth, right lacinia mobilis with 10 small teeth (+), accessory setal row with 2 setae; molar well developed; left incisor with 5 teeth, lacinia mobilis with 5 teeth, without trapezoid plate, accessory setal row with 3 setae; palp 3–articulate. Maxilla 1 outer plate with 7 stout apical setal-teeth. Maxilliped inner plate smaller than outer plate; subrectangular; 2.5 x length of inner plate; palp article 2 setose on inner margin; palp article 4 enlarged, weakly falcate.

Pereon. Pereonites 2 to 7 not fused; pereonites 3 and 4 longest, subequal in length. Pereonite 1 without projections. Gnathopod 1 distinctly smaller than gnathopod 2; propodus triangular, palm begins 1/4 to 1/3 along posterior margin, smooth, without large, rounded knob proximally; dactylus slightly curved, inner margin smooth. Pereonite 2 with small, anterolateral triangular projection. Gnathopod 2 situated toward anterior end or near middle of pereonite 2; basis subequal in length to pereonite 2, with anterodistal projection; ischium with anterodistal projection; propodus subovate, large, anterodistal margin widely concave, with large anterodistal triangular projection, without projections along mid-anterior margin; palm without proximal cavity filled with membranous sack, palm proximal projection with 1 robust (grasping) seta, palm margin irregular, smooth, without hook-like projection at base of dactylus, with broad well developed distal shelf, with two triangular projections distally, with deep, narrow sinus, with large midpalmar projection. Pereonite 3 with subacute anterolateral projection. Pereopod 3 reduced, with 1 article. Pereonite 4 with anterolateral projection. Pereopod 4 reduced, with 1 article. Pereopod 5 well developed, with 6 articles, slender. Pereopods 6 and 7 prehensile. Pereopod 6 basis longest followed by carpus. Pereopod 7 similar to pereopod 6.

Gills on pereonites 3 and 4. Pereonite 3 gill length about 1/3 of corresponding pereonite, straight, ovate. Pereonite 4 gill length about 1/3 of corresponding pereonite or length about 1/2 of corresponding pereonite, straight, ovate.

Pleon. Uropod 1 present; peduncle free, peduncle length about 1.7 x width; ramus length about 4–5 x width.

Female (sexually dimorphic characters). Pereonite 3 with anterolateral triangular projection (large). Pereonite 4 without anterolateral projection. Gnathopod 2 situated near anterior end of pereonite 2; Uropods absent.

Habitat. On the hydroids Macrorhynchia philippina and Halopteris buskii in 4–10 m depth.

Remarks. Orthoprotella pearce looks very similar to O. mayeri . They can be distinguished only with observation of the lateral view and careful examination of the mouthparts. Orthoprotella mayeri has two articles in pereopods 3 and 4, although the distal article is tiny and difficult to detect, while in O. pearce these pereopods are uni–articulate. In connection with the mouthparts, the distal article of the mandibular palp in O. mayeri presents a setal formula 1-x-y-1 with x being more than 20 and y=2-4, while the formula in O. pearce is 1-x-1 with x=7. Furthermore, the distal projection of the third article of the maxilliped palp is present in O. mayeri and absent in O. pearce .

Distribution. Australia. Queensland: Watsons Bay and Coconut Beach, Lizard Island (Guerra-García 2006).

Figures

FIGURE 6. Orthoprotella pearce Guerra-García, 2006. Lateral view. A, holotype male, 5.6 mm, AM P61740; B, paratype female, ~5.5 mm, AM P61741, Pidgin Point, Lizard Island, Great Barrier Reef. Refigured from Guerra-García (2006).