Ampithoe hyalos, 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 : 32-37

Ampithoe hyalos sp. nov.

( Figs 22–25 )

Type material. Holotype: AM P61840, male, 8 mm, Bottle and Glass Rocks, Port Jackson, NSW, 33°51’S 151°16’E, 10 Jul 1981, A. Murray . Paratype: AM P61841, female, 11 mm, type locality .

Diagnosis. Antenna 2 slender, similar to antenna 1, with short, dense setae on ventral margin. Lower lip with lateral lobe longer than medial lobe. Maxilla 1 inner plate with slender setae absent. Gnathopod 1 carpal lobe rounded; carpus subequal to propodus; palm convex, with 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 setae absent; carpus much shorter than propodus; palm acute, entire, with rounded midmedial tooth, with small subacute posterodistal tooth defining palm, with 1 defining robust seta; dactylus subequal in length to palm. Pereopod 3 basis narrow; merus expanded. Pereopods 5–7 simple. Pereopod 5 merus subrectangular. Uropod 3 peduncle with 6 distal robust setae, outer ramus shorter than inner ramus, without patch of small conical lateral denticles, with lateral setal fringe; inner ramus with 4 distal robust setae. Telson distally rounded, apical cusps small.

Description. Based on holotype, male, 8 mm, AM P61840. Head as long as deep. Mandible molar with 6 robust setae in the accessory setal row; palp stout, long, setose along posterior margin, article 1 shorter than article 2 (0.55 x), article 2 longer than article 3 (1.24 x), article 3 longer than article 1 (1.46 x). Lower lip mandibular lobe with curved margins, rounded 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 subequal to gnathopod 2 coxa, produced distoventrally, distoventral margin rounded, anterior margin concave, ventral margin with a row of small setules along ventral margin; basis longer than coxa, with sparse (sometimes plumose) slender setae, posterodistal lobe small and rounded, 2 or 3 slender setae; merus produced to form a small, subacute distoventral lobe, anterior margin with setae absent, carpus longer than merus, subtriangular, anterior margin with slender setae only; propodus narrow (length 1.67 x width), ovoid; palm with 1 defining robust seta; dactylus inner margin denticulate. Gnathopod 2 coxa ventral margin with a row of small setules along ventral margin and with a tuft of long slender setae in the posteroventral corner; basis longer than coxa, with row of robust setae; merus produced to form a short, subacute distoventral lobe, anterior margin with setae absent; carpus longer than merus, subtriangular, anterior margin with slender setae only; propodus broad (length 1.48 x width), subrectangular, not 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 not expanded distally, subrectangular, with 2 distal simple striated robust setae; dactylus slightly 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.

Pleon. Epimeron 3 posteroventral corner broadly rounded. Uropod 1 peduncle with more than 5 robust setae, with a long setal fringe; rami subequal in length; inner ramus with 3–5 marginal robust setae, slender setae absent; outer ramus with 3–5 marginal robust setae, slender setae absent. Uropod 2 peduncle with more than 5 robust setae, slender setae fringe present; inner ramus slightly longer than outer ramus, with 3–5 mar- ginal robust setae, slender setae absent; outer ramus with 3–5 marginal robust setae, slender setae absent. Uropod 3 peduncle longer than broad (1.49 x width), short with respect to the rami length (1.97 x), with 1 or 2 marginal robust setae, marginal slender setae present, with more than 5 distal slender setae; inner ramus with more than 5 distal slender setae. Telson with apical and lateral slender setae.

Female. (Sexually dimorphic characters). Based on paratype, female, 11 mm, AM P61841. Gnathopod 1 subequal in size to gnathopod 2; basis shorter than coxa, posterodistal lobe with 1 slender seta; carpal lobe subacute; palm entire, without midmedial tooth. Gnathopod 2 basis shorter than coxa, with sparse (sometimes plumose) slender setae, posterodistal lobe small and round, with 1 slender seta; carpus shorter than propodus; propodus ovoid; palm without a midmedial tooth .

Etymology. This species name is derived from the Greek for glass, alluding to the type locality, Bottle and Glass Rocks.

Remarks. The strongly subrectangular propodus of gnathopod 2 links Ampithoe hyalos sp. nov. to A. roly sp. nov. and A. caddi Poore & Lowry, 1997 . Ampithoe hyalos is closest in morphology to A. roly . Features distinguishing A. hyalos from A. roly include: the absence of setae on the inner plate of maxilla 1 ( A. roly has one slender seta on the inner plate); gnathopod 2 has a row of robust setae on the basis, but the lobe itself on the basis does not have any setae on the margin ( A. roly gnathopod 1 has a fringe of slender, plumose setae on the basis and the basal lobe has three robust setae on the margin); gnathopods 1 and 2 carpus anterior margins have only slender setae ( A. roly has one robust seta on the anterior margin of gnathopod 1 carpus and no setae on the anterior margin of gnathopod 2 carpus); the propodus of gnathopod 2 is not produced to form an anterodistally setose lobe ( A. roly has the gnathopod 2 propodus produced to form an anterodistally setose lobe); and the palm of gnathopod 2 is acute ( A. roly has a transverse palm on gnathopod 2 propodus).

Distribution. Bottle and Glass Rocks, Port Jackson, New South Wales, Australia.

Figures

FIGURE 22. Ampithoe hyalos sp. nov., holotype, male, AM P61840, 8 mm. Paratype, female, AM P61841, 11 mm. Bottle and Glass Rocks, Port Jackson, New South Wales, Australia.

FIGURE 23. Ampithoe hyalos sp. nov., holotype, male, AM P61840, 8 mm. Bottle and Glass Rocks, Port Jackson, New South Wales, Australia. Scales represent 0.2 mm. Male and female antennae missing.

FIGURE 24. Ampithoe hyalos sp. nov., holotype, male, AM P61840, 8 mm. Paratype, female, AM P61841, 11 mm. Bottle and Glass Rocks, Port Jackson, New South Wales, Australia. Scales represent 0.5 mm.

FIGURE 25. Ampithoe hyalos sp. nov., holotype, male, AM P61840, 8 mm. Bottle and Glass Rocks, Port Jackson, New South Wales, Australia. Scales represent 0.5 mm for pereopods 3–6 and 0.2 mm for uropods 1–3 and telson. Pereopod 7 missing.