Pseudopleonexes burney, Peart, Rachael A., 2006

Peart, Rachael A., 2006, A revision of Pseudopleonexes Conlan, 1982 (Crustacea: Amphipoda: Ampithoidae) with description of three new species from Australia, Zootaxa 1344, pp. 1-22 : 3-9

Pseudopleonexes burney sp. nov.

( Figs. 1–4 )

Type material. Holotype: male, 3 mm, WAM C 38104, reef close to shore, Champion Bay, Geraldton, Western Australia, Australia, 28°45.88’S 114°36.83’E, 28 November 2000, 0.5 m, on Ecklonia radiata on shallow rocky reef at low tide, R. Peart, WA-718.

Paratypes: AM P62561 (female, 4 mm), WAM C 38101 (5 specimens), AM P62562 (3 specimens, type locality; AM P62563 (2 specimens), AM P62564 (2 specimens), AM P62565 (3 specimens), rock platform south of Greenough River mouth, Cape Burney , south of Geraldton, 28°51.77’S 114°38.06’E, 30 November 2000, 0.5 m, mixed brown algae on rock platform, mainly Sargassum sp. and Cystophora sp., R. Peart.

Diagnosis. Antenna 1 subequal in length to antenna 2. Antenna 2 robust, peduncle more expanded than antenna 1 peduncle, not densely setose on ventral margin. Maxilla 1 palp with 2 articles. Gnathopod 1 carpus shorter than propodus, carpal lobe subacute; propodus narrow; palm transverse, entire, without midmedial tooth, without posterodistal tooth defining palm, with one defining robust seta; dactylus overreaching palm. Gnathopod 2 with long setae on margins, not plumose; basis posterodistal lobe large and rounded, with more than three robust setae; carpus longer than merus, shorter than propodus; propodus broad, ovoid, not produced into an anterodistally setose lobe; palm acute, entire, without midmedial tooth, with small subacute posterodistal tooth defining palm, with one defining robust seta; dactylus subequal in length to palm. Pereopod 5 merus ovoid; distal articles very broad. Pereopod 6 distal articles slender. Pereopod 7 distal articles broad. Uropod 3 peduncle without distal robust setae.

Description. Based on holotype male, 3 mm, WAM C38104. Head longer than deep. Epistome and upper lip angle directed posteriorly, at more than 45 degrees. Antenna 1 peduncular article 1 longer than article 2 (1.68 x), article 2 longer than article 3 (1.57 x), article 3 shorter than article 1 (0.38 x); primary flagellum with 11 articles; accessory flagellum absent. Antenna 2 peduncular article 4 subequal in length to article 5; flagellum with 11 articles. Mandible molar well developed, triturating; with four robust setae in the accessory setal row; palp with three articles, stout, long, setose along posterior margin, article 1 shorter than article 2 (0.76 x), article 2 longer than article 3 (1.15 x), article 3 longer than article 1 (1.14 x). Lower lip outer plate notched, with medial and lateral lobes equal in size; mandibular lobe with curved margins, subacute apically. Maxilla 1 palp with 2 articles, with apical slender setae; inner plate with one slender seta. Maxilla 2 inner plate narrow, outer plate broader. Maxilliped outer plate with large robust setae.

Pereon. Coxae long. Gnathopod 1 smaller than gnathopod 2, without densely setose margins; coxa smaller than gnathopod 2 coxa, not produced distoventrally, distoventral margin rounded, ventral margin with a row of small setules and a long tuft of slender setae on the posteroventral corner; basis longer than coxa, with sparse (sometimes plumose) slender setae, posterodistal lobe small and rounded, with one slender seta; merus produced to form a small, rounded distoventral lobe, anterior margin without setae; carpus longer than merus, subtriangular, anterior margin without setae; propodus subrectangular; dactylus inner margin denticulate. Gnathopod 2 coxa ventral margin with a row of small setules; basis longer than coxa, without setae, posterodistal lobe large and rounded, with more than three robust setae; merus produced to form a short, rounded distoventral lobe, anterior margin without setae; carpus subtriangular, anterior margin with slender setae only; dactylus tapering evenly, acute, inner margin denticulate. Pereopod 3 basis expanded; merus anteriorly expanded. Pereopod 4 basis and merus similar to pereopod 3. Pereopods 5–7 strongly prehensile. Pereopod 5 basis with marginal robust setae, without medial slender setae; propodus strongly expanded distally, subrectangular, with three distal simple striated robust setae; dactylus slightly curved. Pereopod 6 basis posterior margin rounded proximally, straight distally, with marginal robust setae, without medial slender setae; merus subrectangular; propodus subrectangular, slightly expanded distally, with three distal simple striated robust setae; dactylus slightly curved. Pereopod 7 basis with marginal robust setae, without medial slender setae; propodus subrectangular, defined distally by one to two simple, striated robust setae.

Pleon. Epimeron 3 posteroventral corner broadly rounded. Uropod 1 reaching to the middle of the peduncle of uropod 2, peduncle with three to five robust setae and a short setal fringe, with distoventral spur absent; inner ramus slightly shorter than outer ramus, with three to five marginal robust setae, slender setae absent; outer ramus with marginal robust setae absent, slender setae absent. Uropod 2 peduncle with broad, rounded laterodistal projection, with more than five robust setae, setal fringe absent; inner ramus slightly longer than outer ramus, with three to five marginal robust setae, slender setae absent; outer ramus with marginal robust setae absent, slender setae absent. Uropod 3 peduncle longer than broad (1.76 x width), long in relation to rami length (2.55 x), marginal robust setae absent, marginal slender setae present, with more than five distal slender setae; rami broad; outer ramus subequal in length to inner ramus, with two large recurved distal robust setae; inner ramus with three to five distal slender setae. Telson subtriangular, with lateral slender setae, denticles absent.

Female (sexually dimorphic characters). Based on paratype, 4 mm, AM P62561. Antenna 1 primary flagellum with 12 articles. Antenna 2 slender, similar to antenna 1; flagellum with seven articles. Gnathopod 1 subequal in size to gnathopod 2; coxa subequal in size to gnathopod 2 coxa; carpal lobe rounded. Gnathopod 2 without densely setose margins; basis shorter than coxa; palm transverse; dactylus overreaching palm.

Etymology. This species name, burney , is taken from Cape Burney near the type locality; used as a noun in apposition.

Remarks. The new Australian Pseudopleonexes species are very similar to the recently described P. s h e a rd i Just, 2002. The three species differ from P. s h e a rd i by maxilla 1 palp having two rather than one article. Pseudopleonexes burney differs from P. justi by: a robust antenna 2 with a peduncle more expanded than antenna 1 peduncle rather than being slender and similar to antenna 1; gnathopod 1 carpal lobe is subacute rather than absent, the carpus is shorter than the propodus rather than subequal in length to the propodus; pereopods 5–7 are strongly prehensile rather than weakly prehensile; pereopod 5 bears very broad distal articles rather than slightly broad distal articles; and pereopod 7 bears broad distal articles rather than slender distal articles. Pseudopleonexes burney differs from P. n e x i s by: a robust antenna 2, with a peduncle more expanded than, rather than similar to the antenna 1 peduncle; the gnathopod 1 carpus has a subacute rather than rounded lobe; gnathopod 2 has simple rather than plumose setae on the margins; the pereopod 7 distal articles are slender rather than broad.

Habitat. Shallow water on algae, usually on Ecklonia radiata , Sargassum sp. and Lobophora sp.

Distribution. The vicinity of Geraldton, Western Australia, Australia.

Figures

FIGURE 1. Pseudopleonexes burney sp. nov., holotype, male, WAM C 38104, 3 mm. Paratype, female, AM P 62561, 4 mm, Champion Bay, Geraldton, Western Australia, Australia.

FIGURE 2. Pseudopleonexes burney sp. nov., holotype, male, WAM C 38104, 3 mm. Paratype, female, AM P 62561, 4 mm, Champion Bay, Geraldton, Western Australia, Australia. Scales represent 0.5 mm for antennae 1 – 2 and 0.2 mm for mouthparts.

FIGURE 3. Pseudopleonexes burney sp. nov., holotype, male, WAM C 38104, 3 mm. Paratype, female, AM P 62561, 4 mm, Champion Bay, Geraldton, Western Australia, Australia. Scales represent 0.5 mm for pereopods 3 – 7 and 0.2 mm for uropods 1 – 3 and telson.

FIGURE 4. Pseudopleonexes burney sp. nov., holotype, male, WAM C 38104, 3 mm. Paratype, female, AM P 62561, 4 mm, Champion Bay, Geraldton, Western Australia, Australia. Scales represent 0.5 mm for pereopods 3 – 7 and 0.2 mm for uropods 1 – 3 and telson.