Ampithoe eremits, 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 : 18-22

Ampithoe eremits sp. nov.

( Figs. 11–13 )

Type material. Holotype: AM P51251, female, ovigerous, 11.0 mm, on algae, Split Solitary Island , Coffs Harbour, NSW, 30°14’30”S 153°10’44”E, 5 Feb 1996, 16 m, I. Takeuchi . Paratypes: AM P51252, male, 10.5 mm, living on red algae, South Solitary Island , Coffs Harbour, NSW, 30°12’19”S 153°15’54”E, 5 Feb 1996, 12 m I. Takeuchi ; AM P51253, males and females (5), 8–10 mm, on algae, Split Solitary Island , Coffs Harbour, NSW, 30°14’30”S 153°10’44”E, 5 Feb 1996, 16 m, I. Takeuchi ; AM P51254, male and females (3), 8– 10 mm, living on red algae, South Solitary Island , Coffs Harbour, NSW, 30°12’19”S 153°15’54”E, 5 Feb 1996, 12 m, I. Takeuchi .

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 three slender setae. Gnathopod 1 carpal lobe subacute; carpus subequal in length to the propodus; palm slightly excavate with a small rounded midmedial tooth, with a small subacute posterodistal tooth defining the palm; dactylus subequal in length to the palm. Gnathopod 2 without densely setose margins; basis posterodistal lobe large and rounded, with more than 3 robust setae; carpus subequal in length to propodus; palm acute, excavate without a midmedial tooth, with a small, subacute posterodistal tooth defining the palm, without a defining robust seta; dactylus subequal in length to the palm. Pereopod 3 basis slightly expanded; merus narrow. Pereopods 5–7 weakly prehensile. Pereopod 5 merus subrectangular. Uropod 3 peduncle with 6 distal robust setae, outer ramus shorter than inner ramus, with patch of small conical lateral denticles, with lateral setal fringe; inner ramus with 7 distal robust setae. Telson distally truncate, apical cusps small.

Description. Based on paratype, male, 10.5 mm, AM P51252. 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 (2.9 x), article 3 shorter than article 1 (0.3 x). Antenna 2 robust, better developed than antenna 1; peduncle article 4 longer than article 5. Mandible molar with 6 robust setae in the accessory setal row; palp stout, long, setose along posterior margin, article 1 shorter than article 2 (0.4 x), article 2 subequal to article 3, article 3 longer than article 1 (2.3 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 subequal to gnathopod 2, without densely setose margins; coxa larger than gnathopod 2 coxa, slightly produced anteroventrally, anteroventral margin produced, rounded, anterior margin convex or straight without setal fringe; basis shorter than coxa, with sparse slender setae, posterodistal lobe large and rounded, with three robust 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 2.1 x width), ovoid, palm excavate, with small rounded, midmedial tooth, with small, subacute posterodistal tooth defining palm; dactylus subequal in length to palm, inner margin denticulate. Gnathopod 2 without densely setose margins; coxa without setal fringe; basis subequal in length to 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 slender setae; propodus broad (length 1.8 x width), ovoid, not produced to form 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, with 3 distal robust setae; dactylus hooked. Pereopod 6 with marginal robust setae, with medial slender setae; basis posterior margin rounded; propodus slightly expanded distally, with 3 distal robust setae; dactylus strongly curved. Pereopod 7 with marginal robust setae, with medial slender setae; propodus slightly expanded distally, with 3 distal robust setae; dactylus strongly curved.

Pleon. Epimeron 3 posteroventral corner narrowly rounded. Uropod 1 peduncle with a short setal fringe; inner ramus longer than outer ramus, with 9 marginal robust setae, slender setae absent; outer ramus with 13 marginal robust setae, slender setae absent. Uropod 2 peduncle with 6 marginal robust setae, setal fringe absent; rami subequal in length; inner ramus with 13 marginal robust setae, slender setae absent; outer ramus with 13 marginal robust setae, slender setae absent. Uropod 3 peduncle longer than broad (1.6 x), short with respect to rami length (2 x), with 2 marginal robust setae, marginal slender setae absent; inner ramus with 7 distal slender setae. Telson with apical slender setae only.

Female (sexually dimorphic characters). Based on holotype, female, 11.0 mm, AM P51251. Antenna 2 slender, similar to antenna 1, not densely setose on ventral margin; peduncle article 4 subequal to article 5; flagellum 28-30 articulate Gnathopod 1 coxa produced anteroventrally, rounded, anterior margin concave; propodus narrow (length 1.6 x width); palm acute, entire, without midmedial tooth, with a single robust setae near inner base of dactylus, with a posterodistal tooth defining palm. Gnathopod 2 propodus broad (length 1.8 x width); palm acute, entire, without a midmedial tooth, with a single robust setae near inner base of dactylus, with a small subacute posterodistal tooth defining palm.

Etymology. The name is Latin for solitary, alluding to the type locality.

Remarks. Ampithoe eremitis sp. nov. is similar to A. caddi Poore & Lowry, 1997 and the species group of A. waialua, J.L. Barnard 1972 , A. ngana Poore & Lowry, 1997 , A. platycera Sivaprakasam, 1970 and A. hinatore J.L. Barnard, 1972 . Ampithoe eremitis and A. caddi both have elongated gnathopods, though differing in structure as follows: the merus of both gnathopod 1 and 2 is produced anteriorly into an acute lobe on A. eremitis , and not so in A. caddi .

The palm structure is more similar to that of species of the Ampithoe waialua species group comprising of A. waialua, J.L. Barnard 1972 , A. ngana Poore & Lowry, 1997 , A. platycera Sivaprakasam, 1970 and A. hinatore J.L. Barnard, 1972 . This group shares an excavate palm on gnathopod 1 in males. Ampithoe waialua and A. ngana both have an anteriorly produced merus on both gnathopods 1 and 2. However, A. eremitis differs from A. waialua by having an excavate palm on gnathopod 2, and by having a more excavate gnathopod 1 palm. The female of A. eremitis also differs from the females of A. waialua by having small posterodistal tooth defining the palms of gnathopods 1 and 2.

The specimens of this new species are also much larger (10–11 mm) than those of A. waialua (4–5 mm), slightly larger than A. hinatore (7–8 mm) and similar in size to A. ngana (10–13 mm).

Habitat. Living on red algae in 12–16 m depth.

Distribution. Coffs Harbour, New South Wales, southeastern Australia.

Figures

FIGURE 11. Ampithoe eremitis sp. nov., holotype, female, 11.0 mm, AM P51251, male, 10.5 mm, AM P51252, Split Solitary Island, Coffs Harbour, New South Wales, Australia.

FIGURE 12. Ampithoe eremitis sp. nov., holotype, female, 11.0 mm, AM P51251, male, 10.5 mm, AM P51252, Split Solitary Island, Coffs Harbour, New South Wales, Australia.

FIGURE 13. Ampithoe eremitis sp. nov., holotype, female, 11.0 mm, AM P51251, male, 10.5 mm, AM P51252, Split Solitary Island, Coffs Harbour, New South Wales, Australia.