Ampithoe rosema, 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 : 78-83

Ampithoe rosema sp. nov.

( Figs 62–65 )

Type material. Holotype: WAM C39544, male, 6 mm, Tish Point , Rosemary Island, Dampier Archipelago, WA, 20°29.671’S 116°35.894’E, 30 Aug 1999, 0.5 m, on Sargassum sp. , R. Peart . Paratypes: WAM C38545, female, 7 mm ; WAM, females and males, 9 specimens, type locality ; AM P61893, 1 specimen, W side of Rosemary Island , Dampier Archipelago, WA, 20°29.590’S 116°34.446’E, 29 Aug 1999, 4 m, coral rubble , R. Peart.

Diagnosis. Antenna 2 slender, similar to antenna 1, with sparse setae on ventral margin. Lower lip with lateral lobe longer than medial lobe. Maxilla 1 inner plate with 6 slender setae. Gnathopod 1 carpal lobe subacute; carpus subequal in length to propodus; palm convex, without midmedial tooth, without posterodistal tooth defining palm; dactylus overreaching palm. Gnathopod 2 with long setae on the margins (not plumose); basis posterodistal lobe large and rounded, with more than 3 robust seta; carpus shorter than propodus; palm acute, excavate, with a subacute midmedial tooth, with a small subacute posterodistal tooth defining palm, without a defining robust seta; dactylus shorter than the palm. Pereopod 3 basis narrow; merus narrow. Pereopods 5–7 simple. Pereopod 5 merus subrectangular. Uropod 3 peduncle with 7 distal robust setae, outer ramus subequal in length to 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 C39544. Head as long as deep. Antenna 1 peduncular article 1 longer than article 2 (1.39 x), article 2 longer than article 3 (2.43 x), article 3 shorter than article 1 (0.29 x); primary flagellum with 15 articles. Mandible molar with 5 or 6 robust setae in accessory setal row; palp stout, long, setose along posterior margin, article 1 shorter than article 2 (0.34 x), article 2 subequal to article 3 (1.07 x), article 3 longer than article 1 (2.75 x). Lower lip 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 without densely setose margins; coxa subequal to gnathopod 2 coxa, produced distoventrally, distoventral margin rounded, anterior margin straight, ventral margin with a row of small setules; basis subequal to coxa, with sparse (sometimes plumose) slender setae, posterodistal lobe large and round, more than 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 more than 3 robust setae and slen- der setae; propodus broad (length 1.48 x width), subrectangular; palm with 1 defining robust seta; dactylus inner margin denticulate. Gnathopod 2 coxa ventral margin with a row of small setules; basis subequal to coxa, with sparse slender setae; merus produced to form a short, acute distoventral lobe, anterior margin with setae absent; carpus longer than merus, subtriangular, anterior margin with 3 or 4 robust setae and slender setae; propodus broad (length 1.11 x width), ovoid, produced into an anterodistally 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 3 distal simple striated robust setae; dactylus strongly curved.

Pleon. Epimeron 3 posteroventral corner narrowly rounded. Uropod 1 peduncle with more than 5 robust setae, with a long setal fringe; 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 2 peduncle with 1 or 2 robust setae, setal fringe absent; rami subequal in length; inner 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 (1.36 x width), long with respect to rami length (2 x), marginal robust setae absent, marginal slender setae absent, with 3–5 distal slender setae; inner ramus with 3–5 distal slender setae. Telson with apical and lateral slender setae.

Female. (sexually dimorphic characters). Based on paratype, female, 7 mm, WAM C38545. Antenna 1 subequal to antenna 2; primary flagellum with 11–20 articles. Antenna 2 slender, similar to antenna 1, with sparse setae on ventral margin; peduncular article 4 subequal in length to article 5; flagellum with 12 articles. Gnathopod 1 subequal in size to gnathopod 2; basis posterodistal lobe small and round, with 2 or 3 robust setae; carpus shorter than propodus (0.74 x), anterior margin with 1 robust setae and slender setae; propodus narrow (length 1.56 x width); dactylus subequal in length to the palm. Gnathopod 2 without densely setose margins; basis shorter than coxa; merus produced to form a small, rounded distoventral lobe; carpus anterior margin with slender setae only; propodus not produced anterodistally; palm entire, without a midmedial tooth, defined by 1 robust seta; dactylus subequal in length to palm.

Etymology. The species name for Ampithoe rosema sp. nov. is derived from the type locality name, Rosemary Island.

Remarks. Ampithoe rosema sp. nov. is similar to another Western Australian species, A. geographe sp. nov. and also to the Andaman sea species Ampithoe rachanoi Peart, 2002 . The differences between A. rosema and A. geographe are discussed under account of the latter.

Habitat. This species occurs mainly on brown algae at 0.5 m depth.

Distribution. Dampier Archipelago, Western Australia, Australia.

Figures

FIGURE 62. Ampithoe rosema sp. nov., holotype, male, WAM C38544, 6 mm. Paratype, female, WAM C 38545, 7 mm. Tish Point, Rosemary Island, Dampier Archipelago, Western Australia, Australia.

FIGURE 63. Ampithoe rosema sp. nov., holotype, male, WAM C38544, 6 mm. Paratype, female, WAM C 38545, 7 mm. Tish Point, Rosemary Island, Dampier Archipelago, Western Australia, Australia. Scales represent 0.5 mm for antennae 1–2 and 0.2 mm for mouthparts. Male antenna 2 missing.

FIGURE 64. Ampithoe rosema sp. nov., holotype, male, WAM C38544, 6 mm. Paratype, female, WAM C 38545, 7 mm. Tish Point, Rosemary Island, Dampier Archipelago, Western Australia, Australia. Scales represent 0.5 mm for male and 0.2 mm for female.

FIGURE 65. Ampithoe rosema sp. nov., holotype, male, WAM C38544, 6 mm. Tish Point, Rosemary Island, Dampier Archipelago, Western Australia, Australia. Scales represent 0.5 mm for pereopods 3–5 and 0.2 mm for uropods 1–3 and telson. Pereopods 6–7 missing.