Paradexamine aequiserrata, Myers & LeCroy, 2009

Myers, Alan A., 2009, Dexaminidae *, Zootaxa 2260 (1), pp. 393-424 : 403-404

Paradexamine aequiserrata sp. nov.

( Figs 7 , 8 )

Type Material. Holotype, male, 2.5 mm, AM P77993, Third Beach, small bay in lee of wind (14°40.2' S 145°26.55' E), hand netting in water column, night lights, 2 m, J.K. Lowry, A.A. Myers & L. Hughes ( QLD 1805 ) . Paratypes, 8 males, 1 female, AM P77994, same data as holotype .

Additional material examined. 1 female, P77995 ( QLD 1732 ) ; 1 male, AM P71344 ( QLD 1805 ) ; 29 males, AM P71407 ( QLD 1805 ) ; 3 males, AM P71527 ( QLD 1805 ) .

Type Locality. Third Beach , Lizard Island, Queensland, Australia (14°40.2'S 145°26.55'E) .

Etymology. From the Greek 'aequalis' = similar and 'serrata' = saw-toothed, referring to the even-sized spines on the distal end of each telson lobe.

Description. Based on holotype, male, 2.5 mm, AM P77993.

Head. Head lateral lobes acute or subacute. Eye huge, more than half length of head, with black central core. Antenna 1 peduncle article 1 without process on posterior margin. Antenna 2 equal to body length; peduncle article 4 broader proximally, finely setulose; flagellum with 30+ articles. Mandible palp absent; incisor process lacking robust setal row. Maxilla 1 palp stout, about three times as long as broad. Labium mandibular lobes acute. Maxilliped palp 4-articulate.

Pereon. Gnathopod 1 carpus longer than propodus; propodus not greatly expanded distally. Gnathopod 2 carpus elongate, slender, longer than propodus. Pereopods 3–7 simple or scarcely prehensile. Pereopod 3 coxa, posterodistal corner rounded; dactylus more than half length of propodus. Pereopods 5–7 of uniform morphology. Pereopod 5 basis subrectangular, with posterodistal lobe, anterior margin with short robust setae. Pereopod 6 basis pyriform, broadest proximally, posteroproximal margin convex, weakly serrate, posterodistal margin concave, smooth. Pereopod 7 coxal gill present; basis slender or moderately expanded, much longer than broad, posterodistal margin concave or straight, smooth or weakly serrated.

Pleon. Segments with the following dorsal spine arrangement (from urosomite 1 forwards): 3.3.3.0.0. 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 serrated, each lobe with multiple serrations of even size and shape, without distal spine, with subdistal robust seta, without subdistal slender seta.

Female (sexually dimorphic characters). Based on paratype, female, 2.5 mm, AM P77994. Eye large, about half or less length of head. Antenna 2 shorter than body length; peduncle article 4 slender, parallel sided, weakly setulose; flagellum with 10–12 articles. Uropod 3 rami lacking long fine setae .

Habitat. Sand bottom in shallow water.

Remarks. This species is very similar to P.rewa Myers, 1985 , from Fiji, from which it differs in the more slender and less serrated basis of pereopod 7, in the more elongated carpus of gnathopod 2 and in the acute eye lobes of the male (rounded in P.rewa ).

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

Figures

FIGURE 7. Paradexamine aequiserrata sp. nov., holotype, male, 2.5 mm, AM P77993, Third Beach, Lizard Island, Great Barrier Reef.

FIGURE 8. Paradexamine aequiserrata sp. nov., holotype, male, 2.5 mm, paratype, female, 2.5 mm, AM P77993,Third Beach, Lizard Island, Great Barrier Reef.