Ampithoe prolata, Hughes, Lauren E. & Peart, Rachael A., 2013

Hughes, Lauren E. & Peart, Rachael A., 2013, New species and new records of Ampithoidae (Peracarida: Amphipoda) from Australian Waters, Zootaxa 3719 (1), pp. 1-102 : 14-19

Ampithoe prolata sp. nov.

( Figs. 6–9 )

Type material. Holotype male, 13.3 mm, dissected, 4 slides, WAM C52208; paratype female, dissected, 1 slide, WAM C52209, Woodman Point, Western Australia (32°8’S 115°44’E), depth unknown, 20 August 1997, coll. D. Mead-Hunter.

Additional material examined. South Australia: Many specimens (including 1A male, 20.0 mm dissected, parts in microvial; 1B male, 13.8 mm, dissected, 1 slide; 1C female, 14.5 mm, dissected, 1 slide), SAMA C6684, Barker Inlet, northern end of Torrens Island, Port Adelaide, Gulf St Vincent (34°45’S 138°31’E), beach seine net, mangroves with Zostera sp. seagrass and algae, 11 December 1995, coll. T. Laperousaz and K. Jones (SARDI); many specimens, SAMA C6683, Barker Inlet, northern end of Torrens Island, Port Adelaide, Gulf St Vincent (34°45’S 138°31’E), 1–2 m, lowtide, beach seine net, mangroves with Zostera sp. seagrass and algae, 11 December 1995, coll. T. Laperousaz and K. Jones (SARDI); many specimens, SAMA C6679, southeast of Garden Island, Port Adelaide, Gulf St Vincent (34°48’S 138°32’E), beach seine net, mangroves with mud and rubble bottom, some seagrass and algae, 12 October 1995, coll. T. Laperousaz; many specimens, SAMA C6680, southeast of Garden Island, Port Adelaide, Gulf St Vincent (34°48’S 138°32’E), beach seine net, mangroves with mud and rubble bottom, some seagrass and algae, 12 October 1995, coll. T. Laperousaz and K. Jones (SARDI); many specimens, SAMA C6681, southeast of Garden Island, Port Adelaide, Gulf St Vincent (34°48’S 138°32’E), 1 m, low tide, beach seine net, mangroves with mud and rubble bottom, some seagrass and algae, 14 September 1995, coll. T. Laperousaz and K. Jones (SARDI); many specimens, SAMA C6682, southeast of Garden Island, Port Adelaide, Gulf St Vincent (34°48’S 138°32’E), beach seine net, mangroves with mud and rubble bottom, some seagrass and algae, 11 December 1995, coll. T. Laperousaz and K. Jones (SARDI); 3 specimens, SAMA C6384, Barker Inlet, Outer Harbour (33°49’00”S 121°20’50”E), September 1986, coll. N. Holmes.

Japan: 2 specimens (including male 13.5 mm), AM P.88427, Tomioka Peninsula, Itoshima, West Kyushu (32°31’N 130°02’E), 6 June 1988, coll. G.J. Edgar.

Type locality. Woodman Point, Western Australia (32°8’S 115°44’E).

Etymology. From prolata, Latin for elongate, referring to the elongate carpus of gnathopod 1.

Diagnosis. Antenna 1 primary flagellum with more than 28 or more articles; accessory flagellum scale-like, 1- articulate. Maxilla 1 outer plate palp article 2 with 9 robust setae. Gnathopod 1 coxa 1 subequal to coxa 2, anterior margin straight, anteroventral corner produced subacute; basis longer than coxa, anterodistal lobes large and rounded, without setae; carpus elongate rectolinear, 1.6 times propodus length, anterior margin lined with slender setae, posterodistal margin lined with slender setae, posterodistal corner with rounded lobe; propodus subrectangular, narrow, palm subacute, straight, defined by subquadrate corner with 1 robust seta. Gnathopod 2 basis longer than coxa, posterior margin with a few sparse slender setae, anterodistal lobes large and rounded, not reaching beyond ischium, corner without setae; ischium anterior lobes rounded; carpus subtriangular, much shorter than propodus, anterior margin without setae; propodus subrectangular, length twice width, palm subchelate, transverse to obtuse, with subquadrate midmedial tooth, subquadrate corner defined by posterodistal apically rounded tooth, without palm defining robust setae; dactylus subequal in length to palm, broad, not tapering, apically blunt, inner margin smooth. Telson apically rounded, with 3 pairs of lateral slender setae, 2 pairs of lateral plumose setae and 5 pairs of apical slender setae.

Description of holotype. Head. Antenna 1 article 1 subequal to article 2 length, posterior margin with 3 robust setae; article 3 length 0.27 times article 1; primary flagellum with 28 articles; accessory flagellum scale-like, 1- articluate. Antenna 2 similar to Antenna 1; peduncle article 4 length 1.1 to article 5; flagellum incomplete. Mandible accessory setal row with 6 robust setae; palp 3-articulate; article 2 with 2 slender setae; article 3 length 3 times width. Lower lip outer plates with slit; lateral lobe distinctly longer than medial lobe, with single pair of apical ducts; mandibular lobes with curved margins, subacute apically. Maxilla 1 inner plate with 1 slender seta; outer plate, palp broad, article 2 with 9 robust setae.

Pereon. Coxae 1–4 as long as broad. Gnathopod 1 smaller than gnathopod 2; coxa 1 subequal to coxa 2, anterior margin straight, anteroventral corner produced subacute; basis longer than coxa, posterior margin with a few slender setae, anterodistal lobes large and rounded, without setae; ischium anterior margin with lobes; merus posterodistal corner subquadrate; carpus elongate rectolinear, length 1.2 times width, 1.6 times propodus length, with broad anterodistal lobe, anterior margin lined with slender setae, posterodistal margin lined with slender setae, posterodistal corner with rounded lobe; propodus subrectangular, narrow, length 1.8 times width, palm subacute, straight, defined by subquadrate corner with 1 robust seta, palm length 0.4 times posterior margin; dactylus subequal in length to palm, inner margin crenate. Gnathopod 2 sexually dimorphic; basis longer than coxa, posterior margin with a few sparse slender setae, anterodistal lobes large and rounded, not reaching beyond ischium, corner without setae; ischium anterior lobes rounded; merus anterodistal corner subacute; carpus subtriangular, much shorter than propodus, length 0.33 times width, 0.4 times propodus length, anterior margin without setae; propodus subrectangular, length twice width, palm subchelate, transverse to obtuse, with subquadrate midmedial tooth, subquadrate corner defined by posterodistal apically rounded tooth, without palm defining robust setae, palm length 0.25 times posterior margin; dactylus subequal in length to palm, broad, not tapering, apically blunt, inner margin smooth.

Pleon. Epimera 1–3 subquadrate, posterior margin weakly convex, posterodistal corner with small acute tooth. Uropod 1 long, reaching past uropod 2 rami; peduncle distoventral spine and setal fringe absent, length 4.5 times width, with 12 robust setae; inner ramus 0.7 times peduncle length, with 8 marginal robust setae subequal in length to outer ramus; outer ramus with 3 marginal robust setae. Uropod 2 peduncle with 6 robust setae, without distoventral spine; inner ramus with 5 marginal robust setae, subequal in length to outer ramus; outer ramus with 4 marginal robust setae. Uropod 3 peduncle much longer than broad, length 2.3 times width, twice the length of the rami, with 2 marginal and 7 distal robust setae, 5 distal slender setae; inner ramus length twice breadth, subequal to outer ramus, with 2 distal robust setae, 4 distal slender setae and 4 lateral robust setae; outer ramus with 2 large recurved distal robust setae, lateral setal fringe and 1 lateral robust seta. Telson subtrapezoidal, apically rounded, with small apical cusps, 3 pairs of lateral slender setae, 2 pairs of lateral plumose setae and 5 pairs of apical slender setae.

Variation. Male from SAMA C6684, 20.0 mm. Antenna 1 primary flagellum with 33 articles.

Remarks. The large subrectangular gnathopod 2 propodus with transverse palm places Ampithoe prolata sp. nov. within the Ampithoe valida S.I. Smith, 1873 species complex, which includes: A. brevipalma Kim & Kim, 1988 ; A. ferox (Chevreux, 1902) ; A. hyalos Peart, 2007 b; A. koreana Kim & Kim, 1988 ; A. laxipodus Appadoo & Myers, 2004 ; A. mascarenensis Appadoo & Myers, 2004 ; A. plumulosa Shoemaker, 1938 ; A. plumulosa tepahue Barnard, 1979 ; A. roly Peart, 2007 b; A. valida Smith, 1873 and A. valida shimizuensis Stephensen, 1944 . Ampithoe lacertosa Bate, 1858 should also be considered within the A. valida complex though the gnathopod 2 propodus angle is developed beyond transverse and is obtuse.

The gnathopod 1 with elongate carpus and anterior setose margin in A. prolata sp. nov. is most similar to A. valida and A. lacertosa . In Ampithoe prolata sp. nov. and A. valida the palm on the male gnathopod 2 is transverse, while in A. lacertosa the palm is obtuse. Ampithoe prolata sp. nov. differs from A. valida in the presence of 3 robust setae on the antenna 1 peduncle article 1 and the absence of setae on the gnathopod 1 basis, which are absent and present respectively in A. valida .

Ampithoe prolata sp. nov. is reported from southern Australia and Tomioka Bay, Japan based on material examined here. Analysis of the closely aligned species, A. valida , highlighted well-defined genetic lineages for populations from the Atlantic and Pacific coast of North America (Pilgrim & Darling 2010; Barnard 1965). Given the large and presently disparate geographic range of A. prolata sp. nov., molecular analysis would be useful to investigate population structure.

In Australian waters, the transverse gnathopod 2 propodus palm in A. prolata sp. nov. is also known for two other Ampithoe , A. hyalos and A. roly . Ampithoe prolata sp. nov. can be distinguished from these species by the elongate carpus of gnathopod 1.

Individuals of A. prolata sp. nov. are relatively large for Australian ampithoids with the largest male from SAMA C6684 sample measuring 20 mm. Specimens were associated with seagrass meadows at both South Australian and Western Australian collection locations.

Distribution. Australia. Western Australia: Woodman Point (current study). South Australia: Port Adelaide (current study). Japan. West Kyushu: Itoshima, Tomioka Peninsula (current study).

Figures

FIGURE 6. Ampithoe prolata sp. nov., holotype male, 13.3 mm, WAM C 52208, Woodman Point, Western Australia, scales 0.1 mm.

FIGURE 7. Ampithoe prolata sp. nov., male, 13.8 mm, SAMA C 6684; female, 14.5 mm, SAMA C 6684, Torrens Island, South Australia, scales 0.1 mm.

FIGURE 8. Ampithoe prolata sp. nov., male, 20 mm, SAMA C 6684, Torrens Island, South Australia.

FIGURE 9. Ampithoe prolata sp. nov., male, 13.5 mm, AM P. 88427, Tomioka Bay, Itoshima, Japan, scales 0.1 mm.