Paradexamine quadratus, Myers & LeCroy, 2009

Myers, Alan A., 2009, Dexaminidae *, Zootaxa 2260 (1), pp. 393-424 : 415-417

Paradexamine quadratus sp. nov.

( Figs 17 , 18 )

Type Material. Holotype, female, 2.4 mm, AM P77999, Picnic Beach , Palfrey Island, Lizard Island (14°41.70' S, 145°26.92'E), subtidal, patch reef, rubble patch with sand bottom, 2 m, S.E. LeCroy, 3 July 2001 ( SEL /LZI-2-1) . Paratype, 1 female, AM P78000, same data as holotype .

Type Locality. Palfrey Island , Lizard Island, Queensland, Australia (14°41.70'S 145°26.92'E) .

Etymology. From the Latin 'quadratus' = square, referring to the almost square basis of pereopod 7.

Description. Based on holotype, female, 2.4 mm, AM P77999.

Head. Head lateral lobes rounded. Eye large, about half or less length of head, composed of clear ommatidia (in alcohol). Antenna 1 peduncle article 1 without process on posterior margin. Antenna 2 very short, one third or less length of body; peduncle article 4 slender, parallel sided, weakly setulose; flagellum with 5 articles. Maxilliped palp 4-articulate.

Pereon. Gnathopod 1 carpus shorter than propodus; propodus not greatly expanded distally. Gnathopod 2 carpus subtriangular, shorter 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 long robust setae. Pereopod 6 basis very broad, subovate, posterior margin strongly convex, strongly serrated. Pereopod 7 coxal gill present, basis strongly expanded, almost as broad as long, posterodistal margin strongly serrated.

Pleon. Segments with the following dorsal spine arrangement (from urosomite 1 forwards): 3.3.3.3.1. Epimeron 2 posterior margin minutely serrate, posteroventral corner subquadrate. Epimeron 3 posterior margin minutely serrate, with strong posteroventral spine and accessory spines. Urosomite 1 with dorsal spine and two dorsolateral spines. Uropod 3 rami lacking long fine setae. Telson lobes distally serrated, each lobe with only 2–3 serrations of uneven size and shape, with distal spine, without subdistal robust seta, with subdistal slender seta.

Male (sexually dimorphic characters). Unknown.

Habitat. Rubble patch with sand bottom.

Remarks. This species is close to P. mozambica Ledoyer, 1979 , but that species has a very elongate pereopod 3 coxa that is drawn out at the posterodistal corner into a long, slender triangular process. In addition, epimeron 3 is 'denticule' on its ventral margin in P. mozambicus whereas in P. quadratus the ventral margin has strong spines. Also, the basis of pereopod 6 is less broad and 'finemente dentele' in P. mozambicus , but broad and strongly serrated in P. quadratus .

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

Figures

FIGURE 17. Paradexamine quadratus sp. nov., holotype, female, 2.4 mm, AM P77999, Palfrey Island, Lizard Island, Great Barrier Reef.

FIGURE 18. Paradexamine quadratus sp. nov., holotype, female, 2.4 mm, AM P77999, Palfrey Island, Lizard Island, Great Barrier Reef.