Sophrosyne abyssi, Lowry & Stoddart, 2010

Lowry, J. K. & Stoddart, H. E., 2010, Sophrosynidae, a new family in the Lysianassoidea (Crustacea: Amphipoda) with a revision of the genus Sophrosyne, Zootaxa 2370 (1), pp. 1-35 : 5-6

Sophrosyne abyssi sp. nov.

( Figs 1 –3)

Type material. HOLOTYPE, female, 5.0 mm, with long non-setose oostegites, AM P.48883, east of Cape Naturaliste , Tasmania, Australia (40°45.94'S 149°01.62'E to 40°46.54'S 149°00.27'E), 2400–2500 m, light grey clay and mud, epibenthic sled, R. T. Springthorpe, 10 December 1986, RV Franklin (stn FR 1086-04).

Type locality. East of Cape Naturaliste , Tasmania, Australia (40°45.94'S 149°01.62'E to 40°46.54'S 149°00.27'E), 2400–2500 m .

Etymology. The specific name refers to the great depth from which the type specimen was obtained.

Diagnostic description. Head lateral cephalic lobe small, narrowly rounded; eyes apparently absent. Antenna 1 peduncular article 1 short, length 1.4 x breadth; accessory flagellum medium length, 0.52 x primary flagellum, article 1 short, 0.8 x article 2; flagellum 7-articulate, without callynophore. Antenna 2 peduncular article 3 0.6 x article 4; flagellum 7-articulate. Mandible incisors with slightly convex margins; palp article 2 slender, 1.2 x article 3, with 1 submarginal posterodistal A2-seta, without D2-setae, article 3 length 3.8 x breadth, without D3-setae, with 4 apical E3-setae. Maxilla 1 outer plate with setal-teeth in a 2/3 arrangement. Maxilla 2 inner plate narrow, outer plate broader; inner plate length 0.6 x outer plate. Maxilliped inner plate subrectangular, without apical nodular robust setae; outer plate submarginal setae long, simple; palp article 2 broad, length 1.8 x breadth, 1 x article 3, article 3 slender, length 2.5 x breadth, dactylus with unguis vestigial. Gnathopod 1 basis length 1.5 x breadth, anterior margin without setae; ischium length 1.3 x breadth; merus, posterior margin with a few slender setae; carpus length 0.5 x propodus; propodus length 1.6 x breadth, posterior margin slightly concave, with robust setae and simple, slender setae, palm margin sinusoidal, posterodistal corner with produced subacute spine bearing vestigial seta. Gnathopod 2 minutely subchelate; ischium length 2.5 x breadth; carpus long, length 3.3 x breadth, posterior margin straight; propodus subrectangular, short, length 1.8 x breadth; palm acute, with convex, smooth margin. Pereopod 3 merus weakly expanded anteriorly. Pereopod 4 merus weakly expanded anteriorly. Pereopod 5 basis moderately expanded posteriorly; merus moderately expanded posteriorly. Pereopod 6 coxa small, slightly lobate posteriorly; merus slightly expanded posteriorly. Pereopod 7 basis posterior margin slightly rounded, minutely crenate, posteroventral margin rounded, posteroventral lobe not extending beyond ischium; merus slightly expanded posteriorly; propodus with setae along anterior margin. Epimeron 3 posterior margin with strong upturned spine above subquadrate posteroventral corner. Urosomite 1 with anterodorsal notch and rounded boss, without lateral flange. Uropod 1 rami subequal in length; outer ramus with 2 dorsal robust setae; inner ramus with 1 dorsal robust seta. Uropod 2 rami subequal in length; outer ramus with robust setae. Uropod 3 peduncle length 1.3 x breadth; rami subequal in length. Telson longer than broad, length 1.3 x breadth, deeply cleft (67%), distal margins incised, with 1 apical slender seta on each lobe.

Remarks. Sophrosyne abyssi has an angled posteroventral corner on epimeron 3 and a deeply cleft telson similar to S. ledoyeri . These taxa differ in the length of mandibular palp article 2, the presence of D3-setae on article 3 in S. abyssi , the setal-tooth arrangement on the outer plate of maxilla 1, the shape of maxillipedal palp article 2, the setation of the posterodistal corner of gnathopod 1 and the length of the telson.

Sophrosyne abyssi shares an angled posteroventral corner on epimeron 3 and a shallow posteroventral lobe on pereopod 7 with S. inverarae and S. murrayi , but differs from both of these species in the maxilla 1 setal-tooth arrangement and in the shape of the gnathopod 2 palm.

Distribution. East of Tasmania, Australia, in 2400–2500 m depth.

Figures

FIGURE 1. Sophrosyne abyssi sp. nov., holotype female, 5.0 mm, AM P.48883, off Cape Naturaliste, Tasmania, Australia.