Ampithoe geographe, Peart, 2007

Peart, Rachael A., 2007, A review of the Australian species of Ampithoe Leach, 1814 (Crustacea: Amphipoda: Ampithoidae) with descriptions of seventeen new species, Zootaxa 1566 (1), pp. 1-95 : 22-27

Ampithoe geographe sp. nov.

( Figs 14–17 )

Type material. Holotype, WAM C38532, male, 6 mm, Canal Rocks , S of Yallingup, SW WA, 33°40.28’S 114°59.67’E, 6 Dec 2000, 0.5 m, on brown algae on rocks near shore, R. Peart . Paratypes: WAM C38533, 1 female, 7 mm ; AM P61835, females and males, 5 specimens, type locality .

Diagnosis. Antenna 2 robust, better developed than antenna 1, not densely setose on ventral margin. Lower lip with lateral lobe longer than medial lobe. Maxilla 1 inner plate with 2 slender setae. Gnathopod 1 carpal lobe subacute; carpus shorter than propodus; palm convex, without midmedial tooth, without posterodistal tooth defining palm; dactylus subequal in length to palm. Gnathopod 2 without densely setose margins; basis posterodistal lobe large and rounded, with more than 3 robust setae and 1 slender seta; carpus much shorter than propodus; palm acute, entire, with a rounded midmedial tooth, with a small subacute posterodistal tooth defining palm, without a defining robust seta; dactylus overreaching palm. Pereopod 3 basis narrow; merus narrow. Pereopods 5–7 weakly prehensile. Pereopod 5 merus subrectangular. Uropod 3 peduncle with 7 distal robust setae, outer ramus shorter than inner ramus, with patch of small conical lateral denticles, without lateral setal fringe; inner ramus with 4 distal robust setae. Telson distally rounded, apical cusps small.

Description. Based on holotype male, 6 mm, WAM C38532. Head as long as deep. Antenna 1 longer than antenna 2; peduncular article 1 longer than article 2 (1.25 x), article 2 longer than article 3 (3.92 x), article 3 shorter than article 1 (0.2 x); primary flagellum with 25 articles. Antenna 2 peduncular article 4 longer than article 5; flagellum 20 articulate. Mandible molar with 5 robust setae in the accessory setal row; palp stout, long, setose along posterior margin, article 1 shorter than article 2 (0.53 x), article 2 subequal to article 3 (0.97 x), article 3 longer than article 1 (1.95 x). Lower lip mandibular lobe with curved margins, subacute apically. Maxilla 1 palp with apical robust setae. Maxilla 2 inner plate narrow, outer plate broader. Maxilliped outer plate with developed setation (robust setae large).

Pereon. Gnathopod 1 without densely setose margins; 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; basis shorter than coxa, with fringe of long, slender, plumose setae, posterodistal lobe small and rounded, 2 or 3 slender setae; merus produced to form a small, rounded distoventral lobe, anterior margin with setae absent; carpus longer than merus, subtriangular, anterior margin with slender setae only; propodus narrow (length 1.5 x width), ovoid; palm with 1 defining robust seta; dactylus inner margin denticulate. Gnathopod 2 without densely setose margins; coxa ventral margin with a row of small setules; basis subequal to coxa, with fringe of long, slender, plumose setae; merus produced to form a short, subacute distoventral lobe, anterior margin with setae absent; carpus subequal in length to merus, subtriangular, anterior margin with slender setae only; propodus broad (length 1.15 x width), ovoid, not produced into an antero- distally setose lobe; dactylus tapering evenly, acute, inner margin denticulate. Pereopod 5 basis with marginal robust setae, with medial slender setae; distal articles slender; propodus slightly expanded distally, subrectangular, with 4 distal simple striated robust setae; dactylus strongly curved. Pereopods 6 and 7 are missing from the specimens.

Pleon. Epimeron 3 posteroventral corner subquadrate. Uropod 1 peduncle with a short setal fringe; inner ramus slightly longer than outer ramus, with 3–5 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 (1.38 x width), short with respect to rami length (1.82 x), marginal robust setae absent, marginal slender setae absent, with more than 5 distal robust setae; inner ramus with 1 or 21 or 2distal slender setae. Telson with apical and lateral slender setae.

Female (sexually dimorphic characters). Based on paratype, female, 7 mm, WAM C38533. Antenna 1 primary flagellum with 27 articles. Antenna 2 slender, similar to antenna 1; flagellum with 25 articles. Gnathopod 1 subequal in size to gnathopod 2; coxa subequal in size to gnathopod 2 coxa; merus produced to form a short, subacute distoventral lobe; carpal lobe truncated. Gnathopod 2 basis shorter than coxa, with sparse (sometimes plumose) slender setae, posterodistal lobe small and round, with more than 3 slender setae; merus produced to form a small, rounded distoventral lobe; carpus longer than merus, shorter than propodus (0.73 x); palm without a midmedial tooth, defined by 1 robust seta; dactylus subequal in length to palm.

Etymology. Ampithoe geographe name is derived from Geographe Bay, which is located near the type locality; used as a noun in apposition.

Remarks. Ampithoe geographe sp. nov. resembles both A. boiana sp. nov. and A. rosema sp. nov. The three species all have the uropod 1 peduncle with a distoventral spur absent on both the male and female, gnathopod 1 palm is entire, gnathopod 2 propodus is not subrectangular and the palm has a midpalmar tooth. Ampithoe geographe and A. rosema differ from A. boiana by both having a subacute carpal lobe on gnathopod 1, whereas A. boiana has a rounded carpal lobe on gnathopod 1. The differences between A. geographe and A. rosema include the size of antenna 2 ( A. geographe antenna 2 is robust, whereas A. rosema has a slender antenna 2), A. geographe gnathopod 1 carpus is shorter than propodus whereas A. rosema gnathopod 1 carpus is subequal in length to propodus, and A. geographe gnathopod 1 dactylus is subequal in length to the palm, whereas A. rosema has the gnathopod 1 dactylus longer than the palm.

Habitat. Mixed brown algae at 0.5 m depth.

Distribution. Southwest Western Australia, Australia.

Figures

FIGURE 14. Ampithoe geographe sp. nov., holotype, male, WAM C 38532, 6 mm. Paratype, female, WAM C 38533, 7 mm. Canal Rocks, south of Yallingup, Western Australia, Australia.

FIGURE 15. Ampithoe geographe sp. nov., holotype, male, WAM C 38532, 6 mm. Paratype, female, WAM C 38533, 7 mm. Canal Rocks, south of Yallingup, Western Australia, Australia. Scales represent 0.5 mm for antennae 1–2 and 0.2 mm for mouthparts.

FIGURE 16. Ampithoe geographe sp. nov., holotype, male, WAM C 38532, 6 mm. Paratype, female, WAM C 38533, 7 mm. Canal Rocks, south of Yallingup, Western Australia, Australia. Scales represent 0.5 mm.

FIGURE 17. Ampithoe geographe sp. nov., holotype, male, WAM C 38532, 6 mm. Canal Rocks, south of Yallingup, Western Australia, Australia. Scales represent 0.5 mm for pereopods 3–5 and 0.2 mm for uropods 1–3 and telson. Coxae for pereopods 3–4 missing, pereopods 6–7 missing.