Nuuanu stuckeyorum, Hughes, L. E. & Bopiah, A., 2013

Hughes, L. E. & Bopiah, A., 2013, New species of Nuuanu (Amphipoda: Nuuanuidae) from Norfolk Island, Torres Strait and the Cocos (Keeling) Islands, Zootaxa 3641 (2), pp. 165-176 : 172-174

Nuuanu stuckeyorum sp. nov.

( Figs 5–7 )

Type material. Holotype, male, 4.9 mm, dissected, 4 slides, AM P.90058; paratype, 1 male, SEM pin mount, AM P.89311; paratype, 2 juvenile females, AM P.90060, off West Island Jetty, Cocos (Keeling) Islands, Indian Ocean (12°05'15"S 96°50'14"E), floating wrack, brown alga Turbinaria sp., 14 October, 2008, coll. L.E. Hughes (MI WA 844).

Type locality. West Island, Cocos (Keeling) Islands, Indian Ocean.

Etymology. Named in honour of Michael and Kate Stuckey, who were tremendous support during fieldwork at Cocos (Keeling) Islands.

Diagnosis. Antenna 1 peduncular article 1 with 2 posteroventral robust setae. Gnathopod 2 propodus rectolinear, posterior margin straight, densely setose, palm extremely acute with 10 robust setae including 2 large palm defining robust setae; dactylus stout, one third the length of the propodus posterior margin. Pereopods 5–6 basis posterior margin straight. Pleonites 1–2 with dorsodistal spine. Epimera 1–3 posterior margin straight, corner subquadrate without tooth. Urosomite 1 without carina.

Description. Based on holotype male, 4.9 mm, AM P.90058.

Head lateral cephalic lobe subquadrate with anteroventral slit; anteroventral corner rounded. Eyes poorly developed, ommatidia separated. Antenna 1 longer than antenna 2; peduncular article 1 subequal in length to article 2, with 2 posteroventral robust setae; article 2 not geniculate, longer than article 3; primary flagellum with 19 articles; accessory flagellum 3-articulate. Antenna 2 peduncular article 2 not produced dorsodistally, article 4 subequal in length to article 5; flagellum with 13 articles. Mandible molar well-developed, triturative, accessory setal row as a dense line of short setae; palp article 1 twice as long as broad, shorter than article 2; article 3 subequal in length to article 2.

Pereon. Gnathopod 1 merus posterodistal corner acute; carpus longer than propodus; propodus palm defined by corner with 2 bifurcate robust setae. Gnathopod 2 merus subquadrate distoventrally; carpus as long as wide, lobate, projecting between merus and propodus; propodus rectolinear, posterior margin straight, densely setose, palm extremely acute with 10 robust setae including 2 large palm defining robust setae; dactylus stout, one third the length of the propodus posterior margin. Pereopod 3 coxa subequal in length to coxa 2. Pereopod 4 coxa posteroventral lobe well-developed, subacute. Pereopods 5–7 distally slender, length increasing sequentially; basis margin castellate. Pereopods 5–6 basis posterior margin straight. Pereopod 7 basis posterior margin convex.

Pleon. Pleonites 1–2 with dorsodistal spine. Epimera 1–3 posterior margin straight, corner subquadrate without tooth. Urosomite 1 without carina. Uropod 1 peduncle with 1 basofacial robust seta; inner ramus subequal to outer ramus, shorter than peduncle. Uropod 2 inner ramus subequal to outer ramus, longer than peduncle. Uropod 3 inner ramus reduced, length twice breadth, 0.5 times length of outer ramus; outer ramus 2-articlute; article 1 length twice breadth, without lateral setae; article 2 minute, length 1.9 times breadth. Telson as long as broad, deeply cleft (greater than 66%), each lobe with 1 apical robust seta.

Remarks. Nuuana stuckeyorum sp. nov. has the dorsal pattern of pleonites 1–2 only with a single dorsodistal spine and urosomite 1 without carina, other species with this formula include N. amikai ; N. castellana ; N. kata ; N. numbadi ; N. rectimana and N. titaseyi . Of these taxa N. stuckeyorum and N. rectimana have the male gnathopod 2 propodus palm extremely acute with posterior margin straight, also seen in N. utwe which lack dorsal spines.

Nuuanu stuckeyorum can be differentiated from N. rectimana and N. utwe by the male gnathopod 2 with the dactylus only one third the length of the palm and the palm defined by two robust setae. In Nuuanu stuckeyorum and N. utwe the male gnathopod 2 propodus posterior margins smooth for the length of the margin, while in N. rectimana the posterior margin has a small projection at the proximal end. The uropod 3 outer ramus is without lateral robust setae in N. stuckeyorum , has one seta in N. utwe and has 2 robust setae in N. rectimana .

Nuuanu stuckeyorum is similar to N. numbadi , in the rounded lateral cephalic lobe, dorsal spine and carina pattern, uropod 3 inner ramus length and the telson form. Unfortunately N. numbadi is only known from female specimens, but can be differentiated by the geniculate antennae 1 and pereopods 5 to 7 bases which are broader and minutely castellate.

Distribution. Australian Territory: Cocos (Keeling) Islands, Indian Ocean (current study).

Figures

FIGURE 5. Nuuanu stuckeyorum sp. nov., male, AM P. 89311, 5.2 mm, off West Island Jetty, Cocos (Keeling) Islands, Indian Ocean. SEM photographs: (A) head lateral view (scale 100 µm); (B) pereopod 7 lateral view (scale 200 µm); (C) whole animal lateral view (scale 200 µm); (D) whole animal dorsal view (scale 100 µm); (E) telson and uropod 3 dorsal view (scale 100 µm); and (F) urosome dorsal view (scale 100 µm).

FIGURE 6. Nuuanu stuckeyorum sp. nov., holotype male, AM P. 90058, 4.9 mm, off West Island Jetty, Cocos (Keeling) Islands, Indian Ocean (scales represent 0.1 mm).

FIGURE 7. Nuuanu stuckeyorum sp. nov., holotype male, AM P. 90058, 4.9 mm, off West Island Jetty, Cocos (Keeling) Islands, Indian Ocean (scales represent 0.1 mm).