Cymadusa heronensis, 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 : 13-18

Cymadusa heronensis sp. nov.

( Figs. 8–11 )

Type material. Holotype: male, 4 mm, AM P61906, 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 Sargassum sp., R. Peart & S. Richards.

Paratypes: AM P61907 (female, 4 mm), AM P61908 (females and males, 10 specimens), type locality.

Other material examined. AM P61909 (females and males, 24 specimens), southern reef flat, Heron Reef, Heron Island, Great Barrier Reef, 23°27’S 151°55’E, from Dictyota sp., 11 February 1999, 0.5 m, R. Peart & S. Richards. AM P61910 (2 specimens), AM P61911 (5 specimens), AM P61912 (28 specimens), AM P61913 (6 specimens), AM P61914 (3 specimens), southern reef flat, Heron Reef, Heron Island, Great Barrier Reef, 23°27’S 151°55’E, from Padina australis , 11 February 1999, 0.5 m, R. Peart & S. Richards. AM P61915 (9 specimens), northern reef flat, Heron Reef, Heron Island, Great Barrier Reef, 23°27’S 151°55’E, 14 February 1999, 0.5 m, from Caulerpa sp., S. Smith.

Diagnosis. Antenna 1 accessory flagellum with one article. Maxilla 1 inner plate with one slender seta. Gnathopod 1 with sparsely 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 a defining robust seta. Gnathopod 2 with long slender 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, without defining robust seta; dactylus shorter than palm, tapering evenly, acute point. Epimeron 3 posteroventral corner narrowly rounded. Uropod 3 peduncle with 3 distal robust setae; outer ramus with patch of small conical lateral denticles, without lateral setal fringe. Telson distally truncate, apical cusps small, with oblique lateral and medial rows of slender setae.

Description. Male (based on holotype male 4 mm, AM P61906). Head as long as deep. Antenna 1 longer than antenna 2; peduncular article 1 subequal to article 2 (1.09 x), article 2 longer than article 3 (3.06 x), article 3 shorter than article 1 (0.3 x); primary flagellum with 21–30 articles. Antenna 2 slender, similar to antenna 1, sparsely setose on ventral margin; peduncular article 4 longer than article 5; flagellum 9-articulate. Mandible triturating; with 5 robust setae in the accessory setal row; palp slender, long, apically setose, article 1 shorter than article 2 (0.56 x), article 2 longer than article 3 (1.11 x), article 3 longer than article 1 (1.61 x). Lower lip 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 smaller than 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, one slender seta; merus anterior margin with setae absent; carpus longer than merus, subtriangular, carpal lobe subacute, anterior margin with slender setae only; propodus broad (length 1.43 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 subequal to coxa, with sparse slender setae, posterodistal lobe small and rounded, with one slender setae; merus anterior margin with setae absent; carpus longer than merus, subtriangular, anterior margin with slender setae only; propodus broad (length 1.09 x width), ovoid, not 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, distally with 3 simple striated robust setae; dactylus strongly curved. Pereopod 6 basis posterior margin rounded, with marginal robust setae, without medial slender setae; merus subrectangular; propodus slightly expanded distally, with 3 distal simple striated robust setae; dactylus strongly 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 3–5 marginal robust setae, slender setae absent. Uropod 2 peduncle with 1 or 2 robust setae, setal fringe absent; inner ramus slightly longer than outer ramus, with 3–5 marginal robust setae, slender setae absent; outer ramus with 1 or 2 marginal robust setae, slender setae absent. Uropod 3 peduncle longer than broad (length 1.28 x width), short with respect to rami length (1.97 x), marginal robust setae absent, marginal slender setae absent, with 3– 5 distal slender setae; outer ramus subequal to inner ramus, with 1 recurved and 1 straight robust seta; inner ramus with 3 distal robust setae, with 3–5 distal slender setae.

Female (sexually dimorphic characters; based on paratype, 4 mm, AM P61907). Antenna 1 peduncular article 1 longer than article 2 (1.18 x), article 2 longer than article 3 (2.48 x), article 3 shorter than article 1 (0.34 x); primary flagellum with 20 articles. Antenna 2 flagellum with seven articles. Gnathopod 1 subequal in size to gnathopod 2; coxa subequal in size to gnathopod 2 coxa; basis subequal in length to coxa, posterodistal lobe reduced, without setae; merus produced to form a short, rounded distoventral lobe; carpal lobe rounded; propodus narrow (length 1.53 x width); palm convex, without midmedial tooth, without posterodistal tooth defining the palm. Gnathopod 2 without densely setose margins; basis posterodistal lobe with 2 or 3 slender setae; palm entire, with a rounded midmedial tooth, defined by 1 robust setae; dactylus subequal in length to palm.

Etymology. This species is named after the type locality, Heron Island.

Remarks. Cymadusa heronensis is similar to C. thagaay sp. nov. Both species have a 1-articulate accessory flagellum on antenna 1, the gnathopod 1 palm is entire and has a distal defining tooth, epimeron 3 does not have a defining tooth, and the uropod 3 peduncle does not have marginal robust setae. However, the two species differ because C. heronensis does not have a robust seta defining the palm of gnathopod 2 (present in C. thagaay ), the gnathopod 2 propodus is not produced to form a setose lobe (lacking in C. thagaay ), and the uropod 3 outer ramus has a patch of lateral denticles (absent in C. thagaay ).

Habitat. Cymadusa heronensis sp. nov. has been collected from the algae Dictyota sp., Padina sp., Sargassum sp. and Caulerpa sp. from 0.5 m depth on the reef flat.

Distribution. Heron Island, Queensland, Australia.

Figures

FIGURE 8. Cymadusa heronensis sp. nov., holotype, male, AM P 61906, 4 mm. Paratype, female, AM P 61907, 4 mm. Heron Island, Queensland, Australia.

FIGURE 9. Cymadusa heronensis sp. nov., holotype, male, AM P 61906, 4 mm. Paratype, female, AM P 61907, 4 mm. Heron Island, Queensland, Australia. Scales 0.2 mm.

FIGURE 10. Cymadusa heronensis sp. nov., holotype, male, AM P 61906, 4 mm. Paratype, female, AM P 61907, 4 mm. Heron Island, Queensland, Australia. Scales 0.5 mm.

FIGURE 11. Cymadusa heronensis sp. nov., holotype, male, AM P 61906, 4 mm. Heron Island, Queensland, Australia. Scales 0.5 mm for pereopods 3 – 7 and 0.2 mm for uropods 1 – 3 and telson.