“Neoxenodice cryophile new species
Material examined. - Holotype, adult female, 7.1 mm, USNM 143918; Moubray Bay, Cape Hallett, Antarctica; gravel and sandy-mud bottom, 250 m depth; 18 January 1972; J. K. Lowry. Paratypes, 1 adult female, 8.0 mm, Z.Cr. 1917; Moubray Bay, Cape Hallett, Antarctica; gravel and sandy-mud bottom, 250 m depth; 18 January 1972; J. K. Lowry. 1 specimen, 5.0 mm, USNM 143919; Cape Bird, Ross Island, Antarctica; gravel and sandy-mud bottom, 250 m depth; 9 January 1972; J. K. Lowry. 1 adult female, 6.0 mm, 1 juvenile female, 4.5 mm, 9 other specimens, USNM 143920; Moubray Bay, Cape Hallett, Antarctica; gravel and sandy-mud bottom, 104 m depth; 17 January 1972; J. K. Lowry.
Diagnosis. - Eyes well developed; flagellum of antenna 2 with 3 articles; palm of gnathopod 2, convex, spinose at posterior border and along margin; peduncle of uropod 2 extending just beyond tip of telson; telson with 2 large setae at apex.
Description. – Female 7.1 mm. Long, thin, caprellid-like; peraeonites 1-4 drawn out, with lateral nodes at coxal attachments 1 and 2; coxae very small, distance between coxae 1-4 over twice their width; eyes well developed, red and white in life; body translucent with areas of yellow and gold around the mouthparts and laterally near the end of each segment, antennae with specks of greenish-yellow pigment; gnathopods, peraeopods, uropods, and telson colourless.
Antenna 1 slightly longer than antenna 2, less than 1/2 body length; peduncle 1.5 times longer than flagellum, article 1 slightly more than 1/2 the length of article 2, articles 2 and 3 subequal; accessory flagellum with 1 article, 1/3 length of flagellum article 1; flagellum with 7 articles, article 1 longest, ventral surface of peduncular articles 2 and 3 and flagellum fringed with long setae. Antenna 2 gland cone present; peduncle nearly 3 times length of flagellum, article 3 nearly 1/2 length of article 4, 1/3 length of article 5; flagellum with 3 articles, article 1 longest, ventral surface of antenna 2 fringed with long setae.
Mandible palp, long, with 3 articles, article 1 shortest, article 2 longest, article 3 expanded distally with about 20 long terminal setae. Incisor serrated, lacinia mobilis present, 4 brush-tipped spines posterior to lacinia mobilis, molar non-triturating. Lower lip outer lobes well developed with man- dibular projections. Upper lip rounded, slightly incised. Maxilla 1 palp with 2 articles, article 2 longest with 6 plumose setae near distal end and 4 terminal spines; outer plate well developed with 8 terminal spines; inner plate reduced, lobate, setae absent. Maxilla 2 inner plate slightly shorter than outer plate with 4 lateral setae and about 10 terminal setae; outer plate with about 13 terminal setae. Maxillipeds well developed, inner plate extending to middle of outer plate, with 3 spines along distal border and 7 plumose setae beginning along lateral border and extending to terminus; outer plate extending just past midpoint of palp article 2, with 7-8 spines along lateral edge; palp with 4 articles, article 2 longest, equal to combined length of other 3 articles, with setae near inner edge, article 3 expanded distally, setae present near distal end, article 4 with spine at apex.
Gnathopod 1 subchelate, smaller than gnathopod 2; coxal plate reduced, situated anteriorly on peraeonite 1, article 2 longest, articles 3 and 4 with setae along ventral border, article 5 elongate, plumose setae along ventral border, article 6 subtriangular, distally truncate, slightly longer than 5, palm rugose, convex, plumose setae along border, dactyl well developed with 1 short spine near apex, dactyl about 2/3 length of propodus. Gnathopod 2 subchelate, nearly 1/4 length of body; coxa 2 smaller than coxa 1, attached along medial edge of peraeonite 2, gill tube-like, as long as article 2, article 2 robust with small setae along posterior border, articles 3 and 4 short and subequal, article 5 compressed, article 6 massive, elliptical, 1.8 times longer than wide, 5 small spines and 1 large spine at posterior edge of palm, palm 1/2 length of propodus with 9 spines and 6 plumose setae along inner surface, dactyl well developed, extending length of palm with a few small setae along posterior border.
Peraeopods 1 and 2 very similar, much reduced in size, article 2 long and narrow with 3 short setae along posterior border, articles 3-6 short with sparse setation, dactyl short; peraeopod 1 with tube-shaped gill slightly longer than article 2; peraeopod 2 with a reduced elliptical gill. Peraeopod 3 long and thin, sparsely setose, coxa 5 larger than coxa 6 or 7, article 2 longer than article 6, articles 4 and 5 subequal, both shorter than 6, dactyl well developed, slightly curved, nearly as long as article 6. Peraeopod 4 long and thin, sparsely setose, coxa small, rounded posteriorly, article 2 thicker than other articles, equal in length to article 6, article 4 shorter than article 5, posterior distal corner produced, article 6 longer than 5 with 1 short spine at articulation of dactyl, dactyl long, curved, nearly as long as article 6. Peraeopod 5 long and thin, sparsely setose, coxa small and round, article 2 thicker than following articles, shorter than article 5 or 6, articles 5 and 6 subequal, article 6 with small spine on anterior margin at articulation with dactyl, dactyl long, curved, nearly 3/4 the length of article 6.
Uropod 1 biramous, long and thin, peduncle extending just beyond tip of telson with 1 or 2 spines on outer distal corner; peduncle subequal to outer ramus; outer ramus with 5 stout spines along outer border, distal end quadrate with 1 short and 1 long spine, a subterminal spine arises from dorsal surface; inner ramus slightly longer than outer ramus with 2 or 3 bifurcate spines arising from dorsal surface, distal end quadrate with 2 subterminal spines and 1 short and 1 long terminal spine. Uropod 2 biramous; peduncle short with 1 spine at each distal corner, peduncle reaches tip of telson, about ¾ length of outer ramus; outer ramus with 3 to 4 lateral spines, 1 subterminal stout spine and 1 short and 1 long terminal spine; inner ramus 1.4 times length of outer ramus, 1 to 2 spines along ramus, 2 subterminal spines, 1 short and 1 long terminal spine. Uropod 3 short lobate peduncle with terminal seta, no rami.
Telson about as long as wide, hemielliptical, entire, with 2 long terminal setae.
Remarks. - Neoxenodice cryophile differs from N. caprellinoides, the only other species in the genus, in the characteristics shown in table I.
In addition mature females of N. cryophile have only three pairs of oostegites on peraeonites 2, 3 and 4, a characteristic as yet unknown for N. caprellinoides. Gammaridean amphipods usually have four pair of oostegites (Barnard, 1969) except Caprogammarus gurjanovae Kudrjaschov & Vassilenko, 1966, which has two pairs on peraeonites 2 and 3. Thus gammaridean amphipods show an even gradation of oostegites from four to two through the families Podoceridae and Caprogammaridae. This lessens the importance of the caprellidean characteristic of two oostegites and strengthens the case of McCain (1968) for merging the suborders Gammaridea and Caprellidea.
N. cryophile is known from the extremely cold stable waters off Cape Bird in McMurdo Sound and off Cape Hallett in Moubray Bay. At Cape Bird it lives in 30 to 200 m of water on a gravel and sandy-mud bottom in a community dominated by the tubicolous polychaete, Spiophanes tcherniai Fauvel, 1951. At Cape Hallett it was possible to observe specimens alive for a short time on the relatively undisturbed bottom collected in the sampling device. The animals were attached to the sandy-mud bottom by the last three peraeopods with their heads upright in the water. They moved in a typical caprellid fashion by attaching and detaching alternately the second gnathopods and last three peraeopods, thus inching from one area to another. I am inclined to believe that N. cryopbile may be restricted in its distribution to the Ross Sea, for it has not been reported in any of the earlier collections from the Antarctic Peninsula nor is it reported by Bellan- Santini (1972) in the recent collections from Adelie Land.”
(Lowry, 1976: 98-104)
