Cymadusa thagaay, 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 : 36-41

Cymadusa thagaay sp. nov

( Figs. 29–32 )

Type material. Holotype: male, 4 mm, AM P62518, Mangrove Beach, Lizard Island, Great Barrier Reef, Queensland, Australia, 14°40.99’S 145°27.63’E, 19 November 1999, 3 m, on Turbinaria sp. and green algae on reef, M. Watson & R. Peart. Paratypes: female, 4 mm, AM P62519; AM P62520, 3 specimens; AM P62521, 8 specimens, type locality.

Other material examined. AM P62522, 2 specimens, Mermaids Cove, Lizard Island, Great Barrier Reef, Queensland, Australia, 14°38.96’S 145°27.14’E, 16 November 1999, 5 m, on Sargassum sp., R. Peart, M. Watson & K. Dempsey. AM P62523, 5 specimens, on coral rubble; AM P62524, 4 specimens, on seagrass and sediment, Coconut Beach, Lizard Island, Great Barrier Reef, Queensland, Australia, 14°40.81’S 145°28.41’E, 17 November 1999, 1.5 m, M. Watson. AM P62525, 35 specimens; AM P62526, 21 specimens, on Turbinaria sp. on reef; AM P62527, 5 specimens, on green algae on reef, Mangrove Beach, Lizard Island, Great Barrier Reef, Queensland, Australia, 14°40.99’S 145°27.63’E, 19 November 1999, 1 m, R. Peart. AM P62528, 2 specimens, south side of Watsons Bay, Lizard Island, Great Barrier Reef, Queensland, Australia, 14°39.96’S 145°26.97’E, 20 November 1999, 5 m, on red algae on reef, K. Dempsey, M. Watson & R. Peart. AM P62529, 21 specimens, off Picnic Beach, southeast side of Palfrey Island, Great Barrier Reef, Queensland, Australia, 14°41.5’S 145°27.05’E, 21 November 1999, 5 m, on Turbinaria sp. on reef, K. Dempsey, M. Watson & R. Peart. AM P62530, 8 specimens, on Padina sp.; AM P62531, 2 specimens, on green algae on reef, off Casaurina Beach, Lizard Island, Great Barrier Reef, Queensland, Australia, 14°40.63’S 145°26.71’E, 21 November 1999, 1 m, on reef, K. Dempsey, M. Watson & R. Peart.

Diagnosis. Antenna 1 accessory flagellum with 1 article. Maxilla 1 inner plate with 1 slender seta. Gnathopod 1 without densely setose margins; merus produced to form a small, subacute distoventral lobe; carpus shorter than propodus; palm acute, entire, with midmedial tooth, with posterodistal tooth defining palm, with 1 defining robust seta. Gnathopod 2 with long setae on margins, not plumose; merus produced to form a short, subacute distoventral lobe; carpus shorter than propodus; palm acute, excavate, without midmedial tooth, with small subacute posterodistal tooth defining palm, with 1 defining robust seta; dactylus subequal in length to palm, tapering evenly, acute. Epimeron 3 posteroventral corner broadly rounded. Uropod 3 peduncle with 3 distal robust setae; outer ramus without patch of small conical lateral denticles, without lateral setal fringe. Telson distally rounded, apical cusps small, with lateral and oblique medial rows of slender setae.

Description. Male (based on holotype, male, 4 mm, AM P62518). Head as long as deep. Antenna 1 longer than antenna 2; peduncular article 1 subequal to article 2 (1.1 x), article 2 longer than article 3 (2.62 x), article 3 shorter than article 1 (0.34 x); primary flagellum incomplete with 3–20 articles. Antenna 2 slender, similar to antenna 1, not densely setose on ventral margin; peduncular article 4 subequal to article 5; flagellum 16 articulate. Mandible molar with 3 robust setae in the accessory setal row; palp stout, long, apically setose, article 1 shorter than article 2 (0.7 x), article 2 longer than article 3 (1.3 x), article 3 subequal to article 1 (1.08 x). Lower lip outer plate with lateral lobe longer than medial lobe; mandibular lobe with curved margins, subacute apically. Maxilla 1 palp well developed, with apical robust setae. Maxilla 2 inner and outer plates narrow. Maxilliped outer plate with developed setation (robust setae large and numerous).

Pereon. Gnathopod 1 coxa subequal to gnathopod 2 coxa, produced distoventrally, distoventral margin rounded, anterior margin straight, ventral margin with a row of slender setae of different lengths, not plumose; basis shorter than coxa, with sparse (sometimes plumose) slender setae, posterodistal lobe small and rounded, setae absent; merus anterior margin with setae absent; carpus longer than merus, subtriangular, carpal lobe subacute, anterior margin with slender setae only; propodus broad (length 1.44 x width), ovoid; dactylus subequal in length to palm, inner margin denticulate. Gnathopod 2 coxa ventral margin with row of slender setae of varying lengths, not plumose; basis subequal to coxa, with sparse slender setae, posterodistal lobe small and rounded, with 1 slender seta; merus anterior margin with setae absent; carpus longer than merus, subtriangular, anterior margin with slender setae only; propodus broad (length 1.22 x width), ovoid, produced into an anterodistally setose lobe; dactylus inner margin denticulate. Pereopod 5 basis with marginal robust setae, without medial slender setae; merus subrectangular; distal articles broad; propodus slightly expanded distally, subrectangular, with 3 distal simple striated robust setae; dactylus strongly curved. Pereopod 6 basis posterior margin rounded proximally, straight distally, with marginal robust setae, without medial slender setae; merus subrectangular; propodus slightly expanded distally, with 2 distal simple striated robust setae; dactylus slightly curved. Pereopod 7 basis with marginal robust setae, without medial slender setae; propodus defined distally by 3–5 simple robust setae.

Pleon. Uropod 1 peduncle with more than 5 robust setae, with long setal fringe; inner ramus slightly longer than outer ramus, with 1 or 2 marginal robust setae, slender setae absent; outer ramus with 3–5marginal robust setae, slender setae absent. Uropod 2 peduncle with 3–5robust setae, setal fringe absent; inner ramus slightly longer than outer ramus, with 3–5marginal robust setae, slender setae absent; outer ramus with 3– 5marginal robust setae, slender setae absent. Uropod 3 peduncle longer than broad (1.32 x width), long in relation to rami length (2.29 x), marginal robust setae and marginal slender setae absent, 3–5 distal slender setae; outer ramus subequal to inner ramus; inner ramus with 2 distal robust setae, with 3–5 distal slender setae.

Female (sexually dimorphic characters; based on paratype female, 4 mm, AM P62519). Antenna 1 primary flagellum incomplete with 9–20 articles. Antenna 2 peduncle article 4 longer than article 5; flagellum with 12 articles. Gnathopod 1 subequal in size to gnathopod 2; merus produced to form a short, rounded distoventral lobe; propodus narrow (length 1.66 x width), subrectangular; palm convex, without midmedial tooth, without posterodistal tooth defining the palm. Gnathopod 2 without densely setose margins; merus produced to form a small, rounded distoventral lobe; palm entire, with a rounded midmedial tooth.

Etymology. The species name is derived from the local Aboriginal word, thaagay, for the large monitor lizards that inhabit Lizard Island (the type locality).

Remarks. Cymadusa thagaay sp. nov. is morphologically similar to C. heronensis sp. nov. In both species the accessory flagellum on antenna 1 is 1-articulate, the gnathopod 1 propodus bears an entire palm and a distal defining tooth, epimeron 3 does not have a defining tooth, and the uropod 3 peduncle does not have marginal robust setae. The two species can be distinguishded as follows: C. thagaay has a robust seta defining the palm of gnathopod 2 (absent in C. heronensis ), the gnathopod 2 propodus is produced to form a setose lobe (not produced in C. heronensis ), and the uropod 3 outer ramus does not have a patch of lateral denticles (present in C. heronensis ).

Habitat. Cymadusa thagaay occurs mostly on brown algae, usually Turbinaria sp. and Sargassum sp, but also on red and green algae.

Distribution. Lizard Island, Queensland, Australia.

Figures

FIGURE 29. Cymadusa thagaay sp. nov., holotype, male, AM P 62518, 4 mm. Paratype, female, AM P 62519, 4 mm. Lizard Island, Queensland, Australia.

FIGURE 30. Cymadusa thagaay sp. nov., holotype, male, AM P 62518, 4 mm. Paratype, female, AM P 62519, 4 mm. Lizard Island, Queensland, Australia. Scales 0.2 mm.

FIGURE 31. Cymadusa thagaay sp. nov., holotype, male, AM P 62518, 4 mm. Paratype, female, AM P 62519, 4 mm. Lizard Island, Queensland, Australia. Scales 0.2 mm.

FIGURE 32. Cymadusa thagaay sp. nov., holotype, male, AM P 62518, 4 mm. Lizard Island, Queensland, Australia. Scales 0.2 mm.