Anamixis bananarama, James Darwin, Thomas & Krapp-Schickel, Traudl, 2011

James Darwin, Thomas & Krapp-Schickel, Traudl, 2011, A new species of Leucothoid Amphipod, Anamixis bananarama, sp. n., from Shallow Coral Reefs in French Polynesia (Crustacea, Amphipoda, Leucothoidae), ZooKeys 92, pp. 1-8 : 3-7

Anamixis bananarama sp. n. Figures 13

Type material.

Holotype, Anamorph male “A”, 2.34mm, UF 26542, Paratype, leucomorph female “B”, 2.10mm; UF 26543; Cook’s Bay, Moorea, French Polynesia, J.D. Thomas collector, 4 December 2009, JDT Moorea 09-4 (South-17.48220:West-149.82530). Wash of backreef rubble, 1-2m. Additional paratypes , female leucomorphs (7 specimens), UF 26544, Cook’s Bay, Moorea, French Polynesia, J.D. Thomas collector, 11 December 2009, JDT-Moorea 09-10 (South 17.59205:West-149.835211) coral rubble, coralgal sand, and coral heads, 2-3m.

Additional material.

Hans-Georg Mueller collector; 27 February to 6 March 1988, shallow reef, Bora Bora.

Diagnosis.

Terminal anamorph males: Eyes with 7 scattered ommatidia; gnathopod 1 greatly reduced, shriveled, persisting in post-transformational stages. Gnathopod 2, basis greatly elongated, narrow; carpus elongate, apically blunt, with reduced setal tufts on medial margin; propodus with sparse mediofacial setal row. Telson elongate for genus, 1.72 times longer than wide.

Description.

Head margin broadly rounded, lacking any defining processes; ventral keel, anterior margin rounded, with small midapical indentation; eyes reduced, consisting of 7 scattered ommatidial facets. Antenna 1, ratio of segments 1-3, 43:33:28, peduncle segment 1 and 2 with 3 and 2 plumose setae respectively; flagellum 6-articulate, articles 3-6 with aesthetascs. Antenna 2, flagellum short, 4-articulate. Maxilliped, inner plates fused, apically produced, apical margin with small concave excavation; outer plates lacking inner lobes; palp article 4, 1.36 times length of article 3. Pereonite 1 with small lateral locking ridge.

Gnathopod 1, coxa greatly reduced, apically bifid; remainder of appendage a small bud, articles 2-5 extremely reduced and shriveled. Gnathopod 2, coxa extending deeper than coxa 3-4, distal margin evenly rounded, bearing 10 mediodistal submarginal setules; basis thin, elongate; carpus slightly curved, blunt, reaching 85 percent of propodus, with 6 medial clusters of setae: 2:(2+3):(3+3):(4+1):3:1, distal margin with 5 small submarginal setules; propodus with single row of 7 mediofacial feeding setae, extending 43 percent of propodus length, posterior margin smooth with 3 submarginal setae, anterior margin with 2 prominent apically truncate processes; dactyl straight, inner surface smooth with paired setae on small process near apex, reaching 83 percent on propodus.

Pereopod 3, coxa smaller than 4, rounded ventrally, anterior and posterior margins straight; remainder of pereopods unremarkable. Pereopod 4, coxa slightly larger than 3, posterior margin slightly expanded, remainder of peropod similar to pereopod 3. Pereopods 5-6, coxae bilobed; pereopod 7, coxa entire. Epimera normal for genus. Uropods 1-2, outer rami shortened, approximately 40 percent of inner ramus. Uropod 3, outer ramus 40 percent of inner ramus, outer and inner rami with 1 and 2 marginal spines respectively. Telson 1.70 times longer than wide, with 2 apical setae.

Leucomorph. Description of female leucomorph. Head, anterior margin rounded, smooth, eyes consisting of 7 scattered ommatidial facets. Antenna 1, ratio of segments 1-3, 33:26:23; flagellum 5-articulate, articles 4 and 5 with aesthetascs. Antenna 2, flagellum short, 5-articulate. Gnathopod 1, coxa moderately reduced, extending to ventral margin of head, apically bifid; carpus shorter than propodus, with two apical recurved spines, anterior margin bare; propodus, posterior margin finely serrate, bearing a thick recurved apical seta. Gnathopod 2, anterior margin of coxa broadly rounded, ventral margin slightly produced, posteroventral corner with small cusp, posterior margin straight; propodus, palm angle transverse, palmar margin defined by series of concavities and processes, corner of palm defined by distinct cusp; dactyl reaching to end of palm. Telson 1.72 times longer than wide, with 2 apical setae.

Etymology.

This species is named for the long recurved carpal lobe on the second gnathopod that resembles the shape of a banana.

Relationships.

Anamixis bananarama shares it closest affinity with Anamixis jebbi from the Madang Lagoon, Papua New Guinea, (Thomas, 1997), with both species having 7 ommatidial facets in both leucomorph and anamorph stages, and a reduced, vestigial first gnathopod in the post transformational anamorph stage. The second gnathopod of Anamixis bananarama differs from Anamixis jebbi in the elongate basis, the more blunt and less setose carpus, and reduced mediofacial setal row (7 in Anamixis bananarama ; 14 in Anamixis jebbi ). Anamixis bananarama exhibits an elongated telson typical of ratios found in Nepanamixis (Thomas, 1997). Both Anamixis jebbi and Anamixis bananarama show transitional characters placing them in a clade by themselves with the elongate telson of Anamixis bananarama placing it nearer to Nepanamixis in this regard. The telson of Anamixis bananarama at 1.70 times longer than wide exceeds that of Anamixis jebbi at 1.32 and approaches the telson ratios typical of the genus Nepanamixis at 1.8-2.0 times longer than wide.

Remarks.

Color in life and in freshly collected and preserved material of both leucomorph and anamorph stages are pale translucent pink. There is faint thin reddish banding on posterior thoracic and abdominal segments. Eyes are red. Ovigerous females contain an average of 7-10 yellow eggs in the marsupium.

The vestigial first gnathopods found in Anamixis bananarama and Anamixis jebbi are persistent morphologies in post transformational anamorphs in both taxa. A number of specimens were examined by the first author to ensure these were not transitional transformational features as reported by Thomas (1997) in Paranamixis clarkae from the Seychelles Islands. In Paranamixis clarkae , transformational anamorphs exhibit small shrunken vestiges of gnathopod 1 which are lost in subsequent molts. Ren (2006) described Paranamixis vestigium from the South China Sea, illustrating similar reduced first gnathopods. In all other aspects Paranamixis vestigium resembles Paranamixis misakiensis described by Thomas (1997) from Japan and examination of a series of anamorph specimens of Paranamixis vestigium is needed to resolve whether these vestigial first gnathopods persist in post-transformational molts.

Habitat.

Specific habitat/host undocumented but assumed to be small asconoid calcareous sponges in protected rubble habitats in backreef environments.

Distribution.

Moorea and Bora Bora, French Polynesia, Pacific Ocean. 1-3m.