Stegocephaloides gunnae, Jørgen Berge, 2003

Jørgen Berge, 2003, Stegocephalidae (Crustacea: Amphipoda) from Australia and New Zealand, With Descriptions of Eight New Species, Records of the Australian Museum 55, pp. 85-112 : 100-103

Stegocephaloides gunnae n.sp.

Figs. 11–13

Type material. HOLOTYPE: MV J40615 , ♀ 5 mm: 38°16.40'S 149°27.60'E, 800 m, south of Point Hicks , Victoria, Australia, 23 Jun. 1986. Collector: M.F. Gomon and party . PARATYPES: MV J24059 , 25 specimens: 38°16.40'S 149°27.60'E, 800 m, south of Point Hicks , Victoria, Australia, 23 Jun. 1986. Collector: M.F. Gomon and party .

Additional material. MV J24004 , 1 immature, 37°07.30'S 150°20.20'E, 520 m, New South Wales, off Eden, 20 Jul. 86 ; MV J24056 , 1 specimen, 38°24.14'S 149°13.07'E, 1220 m, Victoria, south of Point Hicks , 23 Jul. 1986 ; MV J40620 , 24 specimens, 38°21.90'S 149°20.00'E, 1000 m, Victoria, south of Point Hicks , 23 Jul. 1986 ; MV J40621 , 26 specimens, 38°19.60'S 149°24.30'E, 930 m, Victoria, south of Point Hicks , 23 Jul. 1986 ; MV J40626 , 19 specimens, 42°2.20'S 148°38.70'E, 800 m, Tasmania, off Freycinet Peninsula , 27 Jul. 1986 ; MV J24062 , 12 specimens, 42°0.20'S 148°37.70'E, 720 m, Tasmania, off Freycinet Peninsula , 27 Jul. 1986 .

Distribution. Tasmania, Victoria and New South Wales, 500–1220 m.

Diagnosis (see also Table 3): Pleonites dorsally smooth. Antenna 1 flagellum with 5 articles. Antenna 2 peduncle article 4 as long as article 5. Epistome not produced laterally, epistomal plate present. Labrum as long as broad, left lobe reduced. Mandibular incisor toothed, lateral. Lacinia mobilis powerful, expanded laterally. Maxilla 1 outer plate with ST in a pseudocrown, palp uni-articulate. Maxilla 2 outer plate gaping and geniculate. Maxilliped palp dactylus simple and pointed. Pereopod 6 basis posteriorly expanded, expansion rudimentary. Uropod 3 outer ramus uniarticulate. Articulation between urosomites 2 and 3 absent. Telson longer than broad, pointed, cleft.

Description. Rostrum reduced, inconspicuous. Antenna 1 as long as antenna 2; accessory flagellum article 2 present. Antenna 2 peduncle articles 3–5 longer than flagellum; article 3 short, about as long as broad. Epistome curved (convex) and smooth; epistomal plate produced into a small elongate medial ridge covering the entire epistome. Maxilla 1 palp not reaching above the apex of outer plate; outer plate distally subrectangular; ST first row with 6 setae (ST1– 5, ST7); ST 6 absent; gap between ST 5 and ST 7 present; ST A present, located distally, part of first row; ST B present, part of second row; ST C present; inner plate with pappocuspidate setae. Maxilla 2 outer plate setae with distal hooks, setae without distal cleft; inner plate setae row A covering about two thirds of the margin, clearly separated from row B; row A setae pappose; row B setae proximally pappose, distally with cusps present; row C present; row D present, expanded, row elongated towards and beyond row A, setae with many small cusps distally. Maxilliped palp 4-articulate; article 2 distal inner margin weakly produced; inner plate not exceeding base of palp article 2; 2 nodular setae; medial setae-row reduced and transverse, setae pectinate; distal setae-row present; inner setae-row reduced, setae not conspicuously large; outer propodus subovate. Pereopod 2 longer and thinner than pereopod 1; ischium elongate, ratio length to breadth exceeding 1.5, distal posterior margin with plumose setae; propodus subrectangular but distally weakly narrowing, palm absent. Pereopod 4 basis posterior margin with long setae; ischium with plumose setae on distal posterior margin. Pereopod 6 basis submarginally with a row of long plumose setae. Pereopod 7 basis anterior margin straight, distally rounded; medial row of setae present, setae short and robust. Oostegites on pereopods 2–5, gills on pereopods 2–7. Uropods: Uropod 1 peduncle longer than rami; outer ramus longer than inner. Uropod 2 peduncle as long as rami; outer ramus weakly longer than inner. Uropod 3 peduncle about half the length of rami; outer ramus as long as inner. Telson longer than peduncle uropod 3; submarginal setae on apex of each lobe absent.

Male. Pereopod 2 propodus larger in males than in females, urosome ordinary (similar to females).

Etymology. The present species is named after the first author’s mother, Gunn Berge.

Remarks. The morphology of the mouthparts, antennae, pereopod 6 and the uropods makes this a “typical” member of the genus, and closely related to Stegocephaloides tori . Both species are separated from its congeners mainly by the absence of several features (see Table 3), but also by the presence of an epistomal plate.