Paradexamine exilis, Myers & LeCroy, 2009

Myers, Alan A., 2009, Dexaminidae *, Zootaxa 2260 (1), pp. 393-424 : 406-408

Paradexamine exilis sp. nov.

( Figs 9 , 10 )

Type Material. Holotype, male, 1.9 mm, AM P77996, Third Beach (14°40.20'S 145°26.548'E), water column sample at night, small bay in lee of wind, with lights and hand nets over 2 m depth, J. Lowry, A. Myers & L. Hughes ( QLD 1805 ) . Paratype, male, AM P77997, same data as holotype .

Additional material examined. 9 males, AM P77998 ( QLD 1805 ) .

Type Locality. Third Beach , Lizard Island, Queensland, Australia (14°40.20'S 145°26.548'E) .

Etymology. From the Latin 'exilis' = slender, referring to the very slender gnathopod 2.

Description. Based on holotype, male, 1.9 mm, P77996.

Head. Head lateral lobes rounded. Eye huge, more than half length of head, with black central core. Antenna 1 peduncle article 1 with posterodistal blunt process tipped with long setae. Antenna 2 length unknown; peduncle article 4 broader proximally, finely setulose; flagellum unknown. Mandible palp absent; incisor process with robust setal row. Maxilla 1 palp elongate, more than four times as long as broad. Maxilliped palp 4-articulate.

Pereon. Gnathopod 1 carpus subequal in length with propodus; propodus distinctly expanded distally. Gnathopod 2 carpus elongate, slender, subequal in length with propodus. Pereopods 3–7 simple or scarcely prehensile. Pereopod 3 coxa, posterodistal corner with multiple spines; dactylus more than half length of propodus. Pereopods 5–7 of uniform morphology. Pereopod 5 basis weakly ovate, anterior margin with short robust setae. Pereopod 6 basis moderately broad, subovate, posterior margin convex, weakly serrate. Pereopod 7 coxal gill present; basis strongly expanded, almost as broad as long, posterodistal margin scalloped.

Pleon. Segments with the following dorsal spine arrangement (from urosomite 1 forwards): 3.3.3.1.0. Epimeron 2 posteroventral corner produced into a strong spine. Epimeron 3 posterior and ventral margins smooth, with a single strong posteroventral spine. Urosome with urosomites 2–3 fused. Urosomite 1 with dorsal spine and two dorsolateral spines. Uropod 3 rami with many long fine setae. Telson lobes distally smooth, with distal spine, with subdistal robust seta.

Female (sexually dimorphic characters). Unknown.

Habitat. Unknown. Males collected in water column at night.

Remarks. With its elongate and slender gnathopod 2 and posterodistal extension on antenna 1, peduncle article 1, this species resembles P. micronesicus Ledoyer, 1979 . It differs from that species in its rounded lateral cephalic lobes (strongly acute in P. micronesicus ), the pleonal spine formula (1.3.3.3.0 in P. micronesicus , 3.3.3.1.0 in P. exilis ), the projection on antenna 1, peduncle article 1 being a blunt process (acute in P. micronesicus ), the multilobed posterodistal corner on coxa 3 (single spine in P.micronesicus ) and the broad basis of pereopod 7 with its scalloped posterior margin (moderately expanded and serrate in P. micronesicus ).

Distribution. Australia. Queensland: Third Beach, Lizard Island (current study).

Figures

FIGURE 9. Paradexamine exilis sp. nov., holotype, male, 1.9 mm, AM P77996, Third Beach, Lizard Island, Great Barrier Reef.

FIGURE 10. Paradexamine exilis sp. nov., holotype, male, 1.9 mm, AM P77996, Third Beach, Lizard Island, Great Barrier Reef.