Podocerus uncinatus, Kilgallen, 2009

Kilgallen, Niamh M., 2009, Podoceridae *, Zootaxa 2260 (1), pp. 841-860 : 856-859

Podocerus uncinatus sp. nov.

( Figs 10 , 11 )

Type material. Holotype, female, 2.5 mm, AM P70848, Cobia Hole, Lizard Island (1439.154’S 14526.851’E), coral rubble, patches of reef and sand, 17.2 m, P.B. Berents, 25 February 2005 ( QLD 1669 ).

Additional material examined. 1 female, AM P70690 ( QLD 1640 ) .

Type locality. Cobia Hole , Lizard Island, Queensland, Australia (1439.154’S 14526.851’E).

Etymology. After the Latin ‘ uncinatus ’, meaning ‘hooked’ and referring to the hook-like dactylus of pereopod 5.

Description. Based on holotype, female, AM P70848. Gills on pereonites 2–6. Pereonites, pleonites not fused, not produced posterodorsally, and with few dorsal setae.

Head. Antenna 1 peduncle article 2 slightly longer than article 3; accessory flagellum 1-articulate; primary flagellum short, approximately 40% peduncle length, with 3 articles. Antenna 2 distinctly longer than antenna 1. Mandible right incisor with 5 teeth; lacinia mobilis with 4 teeth; accessory setal row with 3 setae; left incisor with 5 teeth; palp stout, article 2 less than twice as long as broad, article 3 about 1.5 times as long as broad, densely setose distally. Maxilla 1 outer plate with 9 stout apical setal-teeth. Maxilliped inner plate quadrilateral; outer plate about twice length of inner plate, inner margin smooth; palp article 2 setose on inner margin; article 3 with moderately dense distal setae; article 4 blunt.

Pereon. Pereonites not fused; not produced posterodorsally, and with few dorsal setae; pereonites 2–6 with gills. Gnathopod 1 coxa acutely produced anterodistally; propodus subtriangular, with about 5 rows of submarginal setae near anterior margin; palm convex, beginning about one-third along posterior margin of propodus, minutely serrate near dactyl hinge, without robust seta at corner of palm; dactylus with 2 accessory teeth, fitting palm. Gnathopod 2 merus with rounded distal projection; propodus large, subovate, length about 1.25 x width; palm margin slightly convex, smooth, without distal shelf, sinus, or midpalmar projection; dactylus short, with distal accessory tooth. Pereopods 3 and 4 well developed. Pereopod 5 basis posterior margin with flange; merus shorter than basis; propodus subequal in length to carpus and merus combined; dactylus short and strongly curved, hook-like, about one-third propodus length. Pereopod 6 basis with flange; merus shorter than basis; propodus shorter than merus and carpus combined; dactylus about half propodus length. Pereopod 7 basis lacking flange; merus about subequal in length to basis; propodus shorter than carpus and merus combined; dactylus about half propodus length.

Pleon. Pleonites not fused, not produced posterodorsally, and with few dorsal setae. Uropod 1 well developed; peduncle lacking distoventral spine; biramous, with inner ramus distinctly longer than peduncle and lacking marginal row of robust setae, outer ramus shorter than peduncle. Uropod 2 well developed; peduncle lacking distoventral spine; biramous with inner ramus about twice peduncle length and lacking marginal row of robust setae, outer ramus slightly shorter than peduncle. Uropod 3 reduced, uni-articulate. Telson apically rounded, posterodorsally produced into subacute knob with 2 apical setae.

Male (sexually dimorphic characters). Males not known.

Habitat. Coral rubble and sandy substrates, 8– 18 m.

Remarks. The female of Podocerus uncinatus is similar to that of P. walkeri walkeri Rabindranath, 1972 (= Platophium laeve Walker, 1904 ), but may be distinguished from that species by the lack of dorsal carinations on the body. The gnathopod 1 propodus of P. uncinatus is stouter and subtriangular in shape, compared to that of P. w. walkeri , which is longer and more triangular. The gnathopod 2 merus of P. w. walkeri is also more acutely produced than that of P. uncinatus .

Though the Australian species described by Haswell are sketchily illustrated and poorly described, thus making accurate comparisons difficult, P. uncinatus appears to differ from P. laevis ( Haswell, 1885) by the relative length and shape of the first antennae. It differs from P. lobatus ( Haswell, 1885) in this character also, as well as lacking the dorsal carination of that species.

Podocerus inconspicuus ( Stebbing, 1888) females have a more elongate, triangular-shaped gnathopod 1 propodus, with a transverse palm compared to the more rounded and oblique palm of this species. The present species also lacks a distal lobe on the basis of gnathopod 2. It also differs from Podocerus t. talegus J.L. Barnard, 1965 , in this latter respect, the P. t. talegus female having an acute process at the anterodistal margin of the basis. In addition, the mandibular palp of P. t. talegus is much more slender and elongate, the gnathopod 1 dactylus is distinctly serrate, while the gnathopod 2 dactylus lacks the accessory tooth of present in P. uncinatus . It is also quite similar to P. talegus lawai J.L. Barnard, 1970 , and P. cristatus ( Thomson, 1879) but lacks the dorsal carination of those species, as well as having a more convex gnathopod 1 palm. Finally it differs from P. talegus levuensis Myers, 1985 , in the form of the gnathopod 1 dactylus, lacking the deep serrations of that species.

Distribution. Australia. Queensland: Lizard Island (current study).

Figures

FIGURE 10. Podocerus uncinatus sp. nov., holotype, female, 2.5 mm, AM P70848, Cobia Hole, Lizard Island, Great Barrier Reef.

FIGURE 11. Podocerus uncinatus sp. nov., holotype, female, 2.5 mm, AM P70848, Cobia Hole, Lizard Island, Great Barrier Reef.