Cymadusa jiigurru, Peart, Rachael A., 2007

Peart, Rachael A., 2007, A review of Australian Cymadusa (Crustacea: Amphipoda: Ampithoidae) with descriptions of eight new species, Zootaxa 1540, pp. 1-53 : 19-24

Cymadusa jiigurru sp. nov.

( Figs. 15–18 )

Type material. Holotype, male, 7 mm, AM P61916, off Casaurina Beach, Lizard Island, Great Barrier Reef, Queensland, Australia, 14°40.63’S 145°26.71’E, 21 November 1999, 1 m, on Padina sp., R. Peart, K. Dempsey & M. Watson.

Paratypes: AM P61917 (female, 7 mm), AM P61918 (females and males, 4 specimens), type locality.

Other material examined. AM P61919, 4 specimens, Mangrove Beach, Lizard Island, Great Barrier Reef, 14°40.99’S 145°27.63’E, 19 November 1999, 1 m, on Turbinaria sp. on reef, M. Watson. AM P61920, 2 specimens, north side of Watson’s Bay, Lizard Island, Great Barrier Reef, 14°39.64’S 145°27.05’E, 20 November 1999, 5 m, on red algae on reef, R. Peart & K. Dempsey. AM P61921, 2 specimens, off Picnic Beach, south side of Palfrey Island, Great Barrier Reef, 14°41.5’S 145°27.05’E, 21 November 1999, 5 m, on Turbinaria sp. on reef, R. Peart, K. Dempsey & M. Watson. AM P61922, 6 specimens; AM P61923, 4 specimens, off Casaurina Beach, Lizard Island, Great Barrier Reef, 14°40.63’S 145°26.71’E, 21 November 1999, 1 m, on green algae, R. Peart, K. Dempsey & M. Watson.

Diagnosis. Antenna 1 accessory flagellum with one article. Maxilla 1 inner plate with 2 slender setae. Gnathopod 1 without densely setose margins; merus produced to form a long, acute distoventral lobe; carpus longer than propodus; palm acute, excavate, without midmedial tooth, with posterodistal tooth defining palm, with 1 defining robust seta. Gnathopod 2 without densely setose on margins; merus produced to form a short, acute distoventral lobe; carpus much shorter than propodus; palm acute, excavate, with subacute midmedial tooth, with small subacute posterodistal tooth defining palm, without defining robust setae; dactylus shorter than palm, not tapering evenly, subacute point. Epimeron 3 posteroventral corner broadly rounded.

Uropod 3 peduncle with 5 distal robust setae; outer ramus without patch of small conical lateral denticles, with lateral setal fringe. Telson distally truncate, apical cusps small, with lateral and oblique medial rows of slender setae.

Description. Male (based on holotype male, 7 mm, AM P61916). Head as long as deep. Antenna 1 longer than antenna 2; peduncular article 1 subequal to article 2 (1.05 x), article 2 longer than article 3 (3.2 x), article 3 shorter than article 1 (0.298 x); primary flagellum incomplete with 19–25 articles. Mandible molar with 6 robust setae in the accessory setal row; palp stout, long, setose along posterior margin, article 1 shorter than article 2 (0.604 x), article 2 shorter than article 3 (0.8 x), article 3 longer than article 1 (2.1 x). Lower lip outer plate with lateral lobe longer than medial lobe; mandibular lobe with curved margins, rounded apically. Maxilla 1 palp well developed, with apical robust setae. Maxilla 2 inner plate narrow, outer plate broader. Maxilliped outer plate with developed setation (robust setae large).

Pereon. Gnathopod 1 coxa larger than gnathopod 2 coxa, produced distoventrally, distoventral margin rounded, anterior margin concave, ventral margin with a row of small setules along ventral margin and with long tuft of slender setae in posteroventral corner; basis longer than coxa, with sparse (sometimes plumose) slender setae, posterodistal lobe small and rounded with one slender seta; merus anterior margin with setae absent; carpus longer than merus, subtriangular, carpal lobe acute, anterior margin with slender setae only; propodus narrow (length 1.51 x width), subrectangular; dactylus overreaching palm, inner margin denticulate. Gnathopod 2 coxa ventral margin, with a row of small setules along ventral margin and with a tuft of long slender setae in the posteroventral corner; basis longer than coxa, with fringe of long, slender, plumose setae, posterodistal lobe small and rounded, with setae absent; merus anterior margin with setae absent; carpus longer than merus, subtriangular, anterior margin with slender setae only; propodus narrow (length 1.61 x width), ovoid, not produced into an anterodistally setose lobe; dactylus inner margin denticulate. Pereopod 5 basis with marginal robust setae and medial slender setae; merus subrectangular; distal articles slender; propodus slightly expanded distally. Pereopod 6 basis posterior margin rounded proximally, straight distally, with marginal robust setae, without medial slender setae; merus subrectangular; propodus not expanded distally, with 3 distal simple striated robust setae; dactylus slightly curved. Pereopod 7 basis with marginal robust setae, without medial slender setae; propodus defined distally by 1 or 2 striated simple robust setae.

Pleon. Uropod 1 peduncle with more than 5 robust setae, and a long setal fringe; inner ramus slightly longer than outer ramus, with more than 5 marginal robust setae, slender setae absent; outer ramus with more than 5 marginal robust setae, slender setae absent. Uropod 2 peduncle with 3–5 robust setae, setal fringe absent; inner ramus slightly longer than outer ramus, with more than 5 marginal robust setae, slender setae absent; outer ramus with more than 5 marginal robust setae, slender setae absent. Uropod 3 peduncle longer than broad (length 1.47 x breadth), short in relation to rami length (1.73 x), with 1 or 2 marginal robust setae, marginal slender setae absent, with 3–5 distal slender setae; outer ramus subequal to inner ramus; inner ramus with 4 distal robust setae, with 3–5 distal slender setae.

Female (sexually dimorphic characters; based on paratype female, 7 mm, AM P61917). Antenna 1 primary flagellum incomplete with 12–20 articles. Antenna 2 slender, similar to antenna 1, with sparse setae on ventral margin; peduncular article 4 longer than article 5; flagellum with 16 articles. Gnathopod 1 subequal in size to gnathopod 2; basis shorter than coxa; merus produced to form a short, subacute distoventral lobe; carpus subequal in length to propodus (1.05 x), carpal lobe truncated; propodus ovoid; palm convex, without posterodistal tooth defining the palm, defined by 2 robust setae; dactylus subequal in length to the palm. Gnathopod 2 basis shorter than coxa, with sparse (sometimes plumose) slender setae, posterodistal lobe with one slender seta; carpus subequal in length to propodus, anterior margin with setae absent; propodus broad (length 1.23 x width); palm entire, without a midmedial tooth, without tooth defining palm, defined by one robust seta; dactylus subequal in length to palm, tapering evenly, acute.

Etymology. This species name is derived from the local aboriginal name for Lizard Island, Jiigurru , the type locality.

Remarks. Cymadusa jiigurru sp. nov. and C brevidactyla ( Chevreux, 1907) are obviously similar owing to the structure of the second gnathopod. Both species have an enlarged gnathopod 2 propodus culminating in an acute, excavate palm with a large acute midmedial tooth. The dactylus does not taper evenly but is rounded and thumb-like with an acute distal tooth. The main differences between the two species lie on gnathopod 1. In C. jiigurru , anterior, coxal margin is concave (in C. brevidactyla this margin is broadly margin); the carpus is considerably longer than the propodus (in C. brevidactyla the carpus is only slightly longer than the propodus); the propodus is subrectangular (in C. brevidactyla the propodus is ovoid); the propodus has a nearly transverse palm, being slightly excavate with a small rounded midmedial tooth and a small subacute posterodistal tooth defining the palm; and the dactylus overreaches the palm (in C. brevidactyla the propodus has an acute, entire palm without either a midmedial or posterodistal tooth and the dactylus is subequal in length to the palm).

Figures

FIGURE 15. Cymadusa jiigurru sp. nov., holotype, male, AM P 61916, 7 mm. Paratype, female, AM P 61917, 7 mm. Lizard Island, Queensland, Australia.

FIGURE 16. Cymadusa jiigurru sp. nov., holotype, male, AM P 61916, 7 mm. Paratype, female, AM P 61917, 7 mm. Lizard Island, Queensland, Australia. Scales 0.5 mm for antennae 1 – 2 and 0.2 mm for mouthparts. Male antenna 2 missing.

FIGURE 17. Cymadusa jiigurru sp. nov., holotype, male, AM P 61916, 7 mm. Paratype, female, AM P 61917, 7 mm. Lizard Island, Queensland, Australia. Scales 0.5 mm.

FIGURE 18. Cymadusa jiigurru sp. nov., holotype, male, AM P 61916, 7 mm. Lizard Island, Queensland, Australia. Scales 0.5 mm for pereopods 3 – 7 and 0.2 mm for uropods 1 – 3 and telson.