Cymadusa wistari, 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 : 46-51

Cymadusa wistari sp. nov

( Figs 37–40 )

Type material. Holotype: male, 6 mm, AM P62534, northern reef flat, Heron Reef, Heron Island, Great Barrier Reef, Queensland, Australia, 23°27’S 151°55’E, 14 February 1999, 0.5 m, from Dictyota sp., Padina sp. and Sargassum sp., R. Peart & S. Richards.

Paratypes: female, 8 mm, AM P62535; females and males, AM P62536, 17 specimens; females and males, AM P62537, 12 specimens; AM P62538, 4 specimens; AM P62539, 8 specimens, type locality.

Diagnosis. Antenna 1 accessory flagellum with 1 article. Maxilla 1 inner plate with 4 slender setae. Gnathopod 1 with long, dense, plumose setae on margins; merus produced to form a small, subacute distoventral lobe; carpus longer than propodus; palm acute, convex, without midmedial tooth, without posterodistal tooth defining palm, with 1 defining robust seta. Gnathopod 2 with long, dense, plumose setae on margins; merus produced to form a short, subacute distoventral lobe; carpus shorter than propodus; palm acute, entire, without midmedial tooth, with small subacute posterodistal tooth defining palm, with 1 defining robust seta; dactylus subequal in length to palm, tapering evenly, acute point. Epimeron 3 posteroventral corner broadly rounded. Uropod 3 peduncle with 5 distal robust setae; outer ramus without patch of small conical lateral denticles, without lateral setal fringe. Telson distally rounded, apical cusps small, with oblique lateral and medial rows of slender setae.

Description. Male (based on holotype male, 6 mm, AM P62534). Head as long as deep. Antenna 1 longer than antenna 2; peduncular article 1 subequal to article 2 (1 x), article 2 longer than article 3 (3.53 x), article 3 shorter than article 1 (0.28 x); primary flagellum with 45 articles. Antenna 2 slender, similar to antenna 1, not densely setose on ventral margin; peduncular article 4 subequal to article 5; flagellum 33 articulate. Mandible molar with 8 robust setae in accessory setal row; palp stout, long, setose along posterior margin; peduncular article 1 shorter than article 2 (0.45 x), article 2 subequal to article 3 (1.021 x), article 3 longer than article 1 (2.19 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 subequal to gnathopod 2 coxa, produced distoventrally, distoventral margin rounded, anterior margin concave, ventral margin with row of slender setae of different lengths, not plumose; basis shorter than coxa, with sparse (sometimes plumose) slender setae, posterodistal lobe reduced, 2 or 3 slender setae; merus anterior margin with setae absent; carpus longer than merus, ovoid, carpal lobe subacute, anterior margin with slender setae only; propodus narrow (length 1.59 x width), ovoid; dactylus subequal in length to palm, inner margin denticulate. Gnathopod 2 coxa ventral margin with a row of slender setae of varying lengths, not plumose; basis longer than coxa, with fringe of long, slender, plumose setae, posterodistal lobe reduced, with setae absent; merus anterior margin with setae absent; carpus longer than merus, subtriangular, anterior margin with slender setae only; propodus broad (length 1.16 x width), ovoid, not produced into an anterodistally setose lobe; dactylus inner margin denticulate. Pereopod 5 basis with marginal robust setae, with medial slender setae; merus subrectangular; distal articles slender; propodus not expanded distally, subrectangular, with 3 distal simple striated robust setae; dactylus strongly curved. Pereopod 6 basis posterior margin sinusoidal, with marginal robust setae, with medial slender setae; merus subrectangular; propodus slightly 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 3–5 simple robust setae.

Pleon. Uropod 1 peduncle with more than 5 robust setae, with short setal fringe; inner ramus slightly longer than outer ramus, with more than 5 marginal robust setae, slender setae absent; outer ramus with 3–5 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 (1.5 x width), short with respect to rami length (1.91 x), with 1 or 2 marginal robust setae, marginal slender setae absent, with 3–5 distal slender setae; outer ramus shorter than inner ramus; inner ramus with 5 distal robust setae, with 3–5 slender distal setae.

Female (sexually dimorphic characters; based on paratype female, 8 mm, AM P62535). Gnathopod 1 subequal in size to gnathopod 2, not densely setose on margins; coxa ventral margin with row of small setules and with long tuft of slender setae on posteroventral corner; basis subequal in length to coxa, posterodistal lobe small and round, with 1 slender seta; merus produced to form a short, rounded distoventral lobe; carpus subequal in length to propodus (1 x), carpal lobe rounded. Gnathopod 2 without densely setose margins; coxal ventral margin with row of small setules and with long tuft of slender setae on posteroventral corner; basis subequal in length to coxa, with sparse (sometimes plumose) slender setae, posterodistal lobe with 1 slender seta; merus produced to form a small, rounded distoventral lobe; carpus subequal in length to propodus; palm without tooth defining palm, defined by 1 robust seta.

Etymology. The species name is derived from Wistari Reef, near the type locality; used as a noun in apposition.

Remarks. Cymadusa wistari sp. nov. is most similar to Cymadusa brevidactyla ( Chevreux, 1907) and Cymadusa elegantis sp. nov. Cymadusa wistari is readily distinguished by having the carpus of gnathopod 1 longer than the propodus, and the palm of gnathopod 2 being entire.

Habitat. Cymadusa wistari sp. nov. lives on the brown algae, Padina australis , Dictyota sp. and Sargassum sp. from depths of 0.5 m.

Distribution. Heron Island, Queensland, Australia.

Figures

FIGURE 37. Cymadusa wistari sp. nov., holotype, male, AM P 62534, 6 mm. Paratype, female, AM P 62535, 6 mm. Heron Island, Queensland, Australia.

FIGURE 38. Cymadusa wistari sp. nov., holotype, male, AM P 62534, 6 mm. Paratype, female, AM P 62535, 6 mm. Heron Island, Queensland, Australia. Scales 0.5 mm for antennae 1 – 2 and 0.2 mm for mouthparts. Female antennae are missing.

FIGURE 39. Cymadusa wistari sp. nov., holotype, male, AM P 62534, 6 mm. Paratype, female, AM P 62535, 6 mm. Heron Island, Queensland, Australia. Scales 0.5 mm.

FIGURE 40. Cymadusa wistari sp. nov., holotype, male, AM P 62534, 6 mm. Heron Island, Queensland, Australia. Scales 0.5 mm for pereopods 4 – 7 and 0.2 mm for uropods 1 – 3 and telson. Pereopod 3 identical to pereopod 4.