Latigammaropsis akhenateni, Myers, A. A., 2014

Myers, A. A., 2014, Amphipoda (Crustacea) from Palau, Micronesia: Families Melphidippidae, Oedicerotidae, Photidae, Pleustidae, Podoceridae, Stenothoidae, Synopiidae and Talitridae, Zootaxa 3811 (4), pp. 535-552 : 539-542

Latigammaropsis akhenateni sp. nov

( Figs 4 , 5 )

Gammaropsis atlantica . — J.L. Barnard, 1970: 174, figs 111–113. (not G. atlantica Stebbing 1888 )

Type material. Male holotype. 4.5 mm ( OUMNH.ZC.2002.24.124) Seabear Site, drop off, from rubble, 16 m depth; 07°16.419' N, 134°31.435'E; leg. S. De Grave & C. Burras, 24 May 2002.

Paratypes: 2 males, 3 females ( OUMNH.ZC.2002.24.125) same station data as holotype.

Other material. 1 male, 1 female ( OUMNH.ZC.2002.24.126) Pkuklim Reef; Halimeda clumps on reef rubble, from Halimeda (Chlorophyta) washings, 6 m depth; 07°20.542' N, 134°34.023'E; leg. S. De Grave & C. Burras, 29 May 2002; 1 male ( OUMNH.ZC.2002.24.127) Western Channel, Baobeldab Island, from Sinularia sp. ( Alcyonacea : Alcyoniidae ) and dead coral base, 20 m depth; 07°32.526' N, 134°28.287'E; leg. S. De Grave & C. Burras, 21 May 2002.

Etymology. Named after the Egyptian King Akhenaten (1352–1336 B.C.).

Description. Based on male holotype, 4.5 mm.

Head. Head elongate with extended lateral cephalic lobes, anteroventral margin deeply recessed, extending far behind posterior margin of eye. Eye large extending dorsally. Labrum without epistome. Labium with acute mandibular processes. Mandible palp article 2 longest, article 3 spatulate. Antenna 1 about three quarters body length; peduncular article 3 longer than article 1; primary flagellum with 13 articles; accessory flagellum with 5 long articles and a vestigial terminal article. Antenna 2 a little shorter than antenna 1, peduncular articles 4 and 5 subequal in length; flagellum with 9 articles.

Pereon. Gnathopod 1 coxa subrectangular, weakly produced; carpus and propodus subequal; propodus palm oblique, evenly rounded. Gnathopod 2 coxa shallow wider than deep; basis robust, anterior margin and inner face bearing profuse, very long and slender setae; carpus short, cup-shaped; propodus almost four times length of propodus; propodus anterior margin densely setose, palm with deep, broad distal excavation, defined by a small spine and with a large robust seta; dactylus stout, without teeth and slightly overlapping inner face of palm. Pereopods 3–4 similar, dactylus less than half length of propodus. Pereopod 5 basis expanded proximally, subovoid. Pereopods 6–7 similar; basis moderately expanded proximally; pereopod 7 only a little longer than pereopod 6.

Pleon. Urosomites 1–2 each with a pair of fine dorsal setae. Uropod 1 peduncle with long distoventral spine, a little over half length of peduncle; inner ramus subequal in length with peduncle; outer ramus three quarters length of inner ramus. Uropod 2 peduncle without distoventral spine; inner ramus a little longer than outer ramus. Uropod 3 peduncle twice as long as wide and longer than inner ramus; outer ramus terminating in a cluster of robust setae; inner ramus more slender than outer ramus, narrowing distally and terminating in a single weak robust seta. Telson with terminal robust seta on each side.

Female. (sexually dimorphic characters). Gnathopod 2 carpus triangular, propodus about two times length of carpus, palm oblique, evenly rounded, defined by a small spine.

Habitat. Among coral rubble and Halimeda sp. and sponge Sinularia sp. over rubble.

Remarks. Stebbing (1888) described Gammaropsis atlantica from Cape Verde. Since that time, the name has been applied to material collected widely in the Indo-Pacific from the Red Sea to Hawaii.

The material figured by Stebbing is a female. It has an enlarged gnathopod 2 of male-like appearance with a relatively deep palmar excavation and strong defining spine. A species lacking strong sexual dimorphism was described from Papua New Guinea by Myers (1995) under the name Gammaropsis gemina Myers. Only material from Eniwetok, Marshall Islands described under the name Eurystheus atlanticus (Stebbing) , by J.L. Barnard (1965), was synonymised by Myers (1995) with this species. Latigammaropsis gemina (Myers) differs from Latigammaropsis atlantica (Stebbing) in its much more strongly developed female gnathopod 2 which has a much larger, broad, flat-bottomed excavation in the palm, a non-crenulate palmar margin and a non-overlapping dactylus.

Within the Indo-Pacific, two quite different phenotypes can be found among materials described under the name Gammaropsis atlantica Stebbing. In one phenotype, the male gnathopod 2 is very setose. Abundant long setae occur on the anterior margin and inner face of the basis and on the anterior margin of the propodus. The other phenotype is weakly setiferous with mainly short setae on the gnathopod 2 basis and propodus. In the setose phenotype, the palm of the male gnathopod 2 terminates in a very weak spine, whereas in the non-setose phenotype, the male gnathopod 2 palm terminates in a strong forward-produced spine.

Material of the setose phenotype has not previously been given specific status and is here described under the name Latigammaropsis akhenateni sp. nov. Whether all world materials described under the name G. atlantica and exhibiting setose gnathopod 2 are conspecific is uncertain. Variations can be discerned among described material and it is possible that material from the Indian ocean, including the Red Sea ( Ruffo, 1969); Zanzibar ( K.H. Barnard, 1937); Madagascar (Ledoyer, 1982 [forma B]; India ( Rabindranath, 1971) and Mauritius ( Appadoo & Myers, 2004), is a distinct species from that described from Pacific in Hawaii ( J.L. Barnard, 1970). Material from Hawaii can be placed with some confidence in the synonymy of L. akhenateni , but the Indian Ocean materials cannot be assigned with certainty.

Latigammaropsis athenae Myers from the Great Barrier Reef has a similar male gnathopod 2 to that of L. akhenateni , but that species has a female gnathopod 2 propodus with an excavate posterior margin.

A species described from Papua New Guinea under the name Gammaropsis afra Stebbing by Myers, 1995, also has a setose male gnathopod 2, but in that material, the propodus of that appendage is elongate and the antennae are relatively short, with the accessory flagellum having only three articles.

Distribution. Hawaii ( J.L. Barnard 1970); Palau (present study).

Figures

FIGURE 4. Latigammaropsis akhenateni sp. nov., male, holotype, 4.5 mm, Seabear Site, Palau.

FIGURE 5. Latigammaropsis akhenateni sp. nov., male, holotype, 4.5 mm, female paratype, 5.0 mm, Seabear Site, Palau.