Ampithoe hiana, 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 : 27-32

Ampithoe hiana sp. nov.

( Figs 18–21 )

Type material. Holotype: AM P61836, male, 5 mm, shallow lagoon, Heron Reef , Heron Island, Great Barrier Reef, QLD, 23°27’S 151°55’E, 13 Feb 1999, 1.4 m, on Dictyota sp. , R. Peart & S. Richards . Paratypes: AM P61837, female, 6 mm ; AM P61838, 52 females and males ; AM P61839, 15 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 1 slender seta. Gnathopod 1 carpal lobe subacute; carpus shorter than propodus; palm excavate, with midmedial tooth, with posterodistal tooth defining palm; dactylus overreaching palm. Gnathopod 2 with long setae on margins, not plumose; basis posterodistal lobe small and rounded, with 2 or 3 robust setae; carpus shorter than propodus; palm acute, excavate, with a subquadrate midmedial tooth, with a small subacute posterodistal tooth defining palm, without a defining robust seta; dactylus subequal in length to the palm. Pereopod 3 basis narrow; merus narrow. Pereo- pods 5–7 simple. Pereopod 5 merus subrectangular. Uropod 3 peduncle with 3 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 3 distal robust setae. Telson distally rounded, apical cusps small.

Description. Based on holotype, male, 5 mm, AM P61836. Head as long as deep. Antenna 1 longer than antenna 2; peduncular article 1 longer than article 2 (1.2 x), article 2 longer than article 3 (2.7 x), article 3 shorter than article 1 (0.298 x); primary flagellum with 18–26 articles. Antenna 2 peduncular article 4 longer than article 5; flagellum 10-articulate. Mandible molar with 5 robust setae in accessory setal row; palp slender, long, setose along posterior margin, article 1 shorter than article 2 (0.43 x), article 2 subequal to article 3 (1 x), article 3 longer than article 1 (2.3 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 reduced setation (robust setae small).

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; basis subequal to coxa, with sparse (sometimes plumose) slender setae, posterodistal lobe small and rounded, 1 slender seta; merus produced to form a long, subacute distoventral lobe, anterior margin with setae absent; carpus longer than merus, subtriangular, anterior margin with three robust setae; propodus narrow (length 1.51 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 longer than coxa, with sparse slender setae; merus produced to form a short, subacute distoventral lobe, anterior margin with setae absent; carpus longer than merus, subtriangular, anterior margin with 1 robust seta and slender setae; propodus broad (length 1.03 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. 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 without marginal robust setae, without medial slender setae; propodus defined distally by 3–5 simple robust setae.

Pleon. Epimeron 3 posteroventral corner broadly rounded. Uropod 1 peduncle with more than 5 robust setae, with a 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 3–5 robust setae, setal fringe absent; inner ramus slightly longer than outer ramus, with 3–5 marginal robust setae, slender setae absent; outer ramus with three marginal robust setae, slender setae absent. Uropod 3 peduncle longer than broad (1.29 x width), long with respect to rami length (2 x), with marginal robust setae absent, marginal slender setae absent, distal slender setae absent; inner ramus with 1 or 21 or 2distal slender setae. Telson with oblique lateral and medial rows of slender setae.

Female. (sexually dimorphic characters). Based on paratype, female, 6 mm, AM P61837. Antenna 1 peduncular article 1 subequal in length to article 2 (1.06 x); primary flagellum with 20-articulate. Antenna 2 slender, similar to antenna 1; flagellum with 14-articulate. Gnathopod 1 subequal in size to gnathopod 2; basis shorter than coxa; merus produced to form a short, subacute distoventral lobe; carpus anterior margin with slender setae only; propodus broad (length 1.42 x width), ovoid; palm entire, without midmedial tooth; dactylus subequal in length to the palm. Gnathopod 2 without densely setose margins; basis shorter than coxa, posterodistal lobe with 1 slender seta; carpus anterior margin with slender setae only; propodus not produced anterodistally; palm entire, without a midmedial tooth, defined by 1 robust seta.

Etymology. This species name is a combination of letters (in part taken from the type locality) to form a word.

Remarks. Ampithoe hiana sp. nov. belongs to the group of species in the genus that includes A. ngana Poore & Lowry, 1997 , A. eremitis Peart, 2002 , A. pseudongana sp. nov. and A. peronana sp. nov., but is morphologically closest to A. pseudongana . The main differences between A. hiana and A. pseudongana are: the setation of maxilla 1 palp ( A. hiana has only 1 slender seta whereas A. pseudongana has 3 slender setae); the shape of the propodus and palm of gnathopods 1 and 2 ( A. hiana has a midpalmar tooth on the palm of gnathopod 1 and the dactylus is longer than the palm and gnathopod 2 is covered with long slender simple setae, the basis posterodistal lobe is small with 3 robust setae, the palm is excavate with a subquadrate midpalmar tooth and is not defined by a robust seta, whereas A. pseudongana gnathopod 1 does not have a midpalmar tooth and the dactylus is subequal in length to the palm, gnathopod 2 is only sparsely setose, the basis posterodistal lobe is large with greater than 3 slender setae, the palm is entire, has a rounded midpalmar tooth and is defined by a single robust seta); and the setation on the rami and peduncle of uropods 3 ( A. hiana uropod 3 peduncle has 3 distal robust setae, the outer ramus is subequal in length to the inner ramus, and the inner ramus possesses 3 distal robust setae, whereas A. pseudongana uropod 3 peduncle has 10 distal robust setae, the outer ramus is shorter than the inner ramus and the inner ramus possesses 7 distal robust setae).

Habitat. Brown algae, mainly Dictyota sp.

Distribution. Heron Island, Queensland, Australia.

Figures

FIGURE 18. Ampithoe hiana sp. nov., holotype, male, AM P61836, 5 mm. Paratype, female, AM P61837, 6 mm. Heron Island, Queensland, Australia.

FIGURE 19. Ampithoe hiana sp. nov., holotype, male, AM P61836, 5 mm. Paratype, female, AM P61837, 6 mm. Heron Island, Queensland, Australia. Scales represent 0.5 mm for antennae 1–2 and 0.2 mm for mouthparts. Right mandible twisted.

FIGURE 20. Ampithoe hiana sp. nov., holotype, male, AM P61836, 5 mm. Paratype, female, AM P61837, 6 mm. Heron Island, Queensland, Australia. Scales represent 0.5 mm.

FIGURE 21. Ampithoe hiana sp. nov., holotype, male, AM P61836, 5 mm. Heron Island, Queensland, Australia. Scales represent 0.5 mm for pereopods 3–7 and 0.2 mm for uropods 1–3 and telson.