Podocerus casuarinensis, Kilgallen, 2009

Kilgallen, Niamh M., 2009, Podoceridae *, Zootaxa 2260 (1), pp. 841-860 : 844-845

Podocerus casuarinensis sp. nov.

( Figs 3 , 4 , Pl. 6B)

Type material. Holotype, female, 3 mm, AM P71219, Casuarina Beach , Lizard Island (14°40.38’S 145°26.69’E), fine sediment in grass beds, sandy bottom with rubble, algae & sparse seagrass, 1 m, S. LeCroy, 2 March 2005 ( QLD 1771 ).

Type locality. Casuarina Beach , Lizard Island, Queensland, Australia (14°40.38’S 145°26.69’E) .

Additional material examined. 1 female, AM P76252 ( QLD 1625 ) ; 1 female, AM P70576 ( QLD 1627 ) ; 1 female, AM P70651 ( QLD 1635 ) .

Etymology. Named for the type locality.

Description. Based on holotype, female, 3 mm, AM P71219.

Head. Eyes large, protruding. Antenna 1 between 0.3–0.5 body length; accessory flagellum present, 1- articulate; primary flagellum about 40% of peduncle length, with 4–5 articles. Antenna 2 distinctly longer than antenna 1, flagellum with 4–5 articles. Mandible incisor with 5 teeth; molar well developed. Maxilliped inner plate smaller than outer plate, quadrilateral; outer plate about twice length of inner plate, inner margin with row of robust setae, with a few fine setae; palp article 2 scarcely setose on inner margin; article 3 with few distal setae; article 4 reduced, blunt.

Pereon. Pereonites not fused; pereonites 2–6 with gills; pereonites 6–7 posterodorsally produced; pereonite 7 with clump of dorsal setae. Gnathopod 1 propodus triangular to subtriangular; palm transverse, minutely serrate, beginning less than halfway along posterior margin of propodus; dactylus fitting palm, with 1 accessory tooth. Gnathopod 2 coxa reduced; basis with rounded anterodistal lobe; merus with short, blunt distal projection; propodus large, subovate, length about 1.5 x width; palm defined by small proximal projection with 2 robust setae, minutely serrate, without distal shelf sinus or midpalmar projection. Pereopods 3–4 well developed; basis narrow, cylindrical. Pereopod 5 basis subrectangular, slightly longer than merus; carpus distinctly longer than merus; propodus slightly shorter than carpus and merus combined; dactylus longer than half propodus length. Pereopod 6 basis and carpus subequal in length, shorter than merus; propodus subequal in length to carpus and merus combined; dactylus longer than half propodus length. Pereopod 7 similar to pereopod 6; propodus shorter than carpus and merus combined.

Pleon. Pleonites not fused; pleonites 1 and 2 posterodorsally produced; pleonite 1 with clump of dorsal setae. Uropods 1 and 2 well developed; peduncle without distoventral spine; biramous with inner ramus distinctly longer than peduncle, lacking marginal row of robust setae, but with row of fine denticles on inner margins. Uropod 3 uni-articulate. Telson apically rounded, posterodorsally produced into subacute knob with 2 apical setae.

Habitat. In sea grass beds on fine sediment, and on rubble algae and seagrass over sandy substrate, 1–2.5 m.

Male (sexually dimorphic characters). Males not known.

Remarks. The present species differs from the female of Podocerus crenulatus Myers, 1985 , by the 1- articulate accessory flagellum; the shape of articles 4 and 5 of the second antenna; the more transverse nature of the gnathopod 1 palm; the lack of dorsolateral lobes on pereonite 7 and pleonites 1–2; and the apically rounded telson. Podocerus crenulatus females, conversely, have a 2-articulate accessory flagellum, a distomedial inflated article 4 and a curved article 5 of antenna 2, an oblique gnathopod 1 palm, distinct dorsolateral lobes on pereonite 7 and pleonites 1–2, and a subtriangular telson.

Podocerus casuarinensis differs from the female of P. sandroruffoi Ortiz & Lalana, 2003 , by the serrated gnathopod 1 palm margin; the lack of serrations on the inner margin of the gnathopod 1 dactylus; the more ovate gnathopod 2 propodus; the relative lengths of the uropods 1–2 rami; and the shape of the telson. In P. sandroruffoi the gnathopod 1 palm is not serrated, but the inner margin of the dactylus of the same appendage is serrated, the gnathopod 2 propodus of the female is more subtriangular in shape, the inner rami of uropods 1 and 2 are shorter than their respective peduncles, and the telson is subquadrate in shape.

Podocerus inconspicuus ( Stebbing, 1888) is also morphological similar, but lacks the dorsal carination of this species, and the gnathopod 1 palm begins more than halfway along the posterior margin of the gnathopod 1 propodus, whereas it begins about one-third of the way along the posterior margin in P. casuarinensis .

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

Figures

FIGURE 3. Podocerus casuarinensis sp. nov., holotype, female, 3 mm, AM P71219, Casuarina Beach, Lizard Island, Great Barrier Reef.

FIGURE 4. Podocerus casuarinensis sp. nov., holotype, female, 3 mm, AM P71219, Casuarina Beach, Lizard Island, Great Barrier Reef.