Pentaceration kermadecia, Just, Jean, 2011

Just, Jean, 2011, Remarkable Australasian marine diversity: 18 new species in Pentaceration Just, 2009 (Crustacea, Isopoda, Paramunnidae), Zootaxa 2813, pp. 1-54 : 20-21

Pentaceration kermadecia sp. nov.

Figures 12–13

Type fixation. Holotype, female, here designated.

Etymology. The species is named for the type locality, the Kermadec Trench.

Material examined. Holotype, Ƥ, 2.9 mm, Kermadec Trench, 36º07'S, 175º52'W, 5340– 5230 m, 23 February 1952, Galathea Expedition 1950 –1952, stn 661, ZMUC CRU- 20443 (with 2 slides).

Description (adult female, holotype). Body elongate, slightly tapering towards pleon; width 0.28 length, widest between pereonites 2 and 3. Head length 0.30 width; length posterior to eyestalks 0.7 anterior length. Frontal margin mid-spine 50º triangle, length equals mid length of pereonite 2, lateral spines similar to, but slightly longer than mid-spine, diverging at 115°, all 3 spines with denticulate margins. Eyestalks overreaching pereonite 1 with approximately half their length, pointing directly laterad, anterior and posterior margins parallel, apex distally denticulate with small terminal spine.

Pereonites 1–4 with single broad, bluntly pointed middorsal spine, pereonites 5–6 with single smaller round mid-dorsal spine. Pereonite 1 lateral margins rounded with denticulate margins; pereonite 2 and 3 lateral spines diverging at 35°; pereonites 2 and 3 and 5–7 lateral spines triangular with broad base, acutely pointed, with denticulate margins, 6 and 7 with rounded projection on mid-anterior margin; pereonite 4 lateral spines approximately 1/ 4 length of adjacent pereonite spines; pereonites 5 and 6 with fringe of simple setae posterolaterally where overlapping succeeding pereonite.

Pleon length 1.25 width. Pleonite 1 width 0.72 distance between uropods, length 0.15 width. Pleotelson with short proximal neck; proximal and lateral margins forming evenly merging curve, lateral margins evenly convex, with 11 to 12 denticles; distal projection triangular at 85°, 0.24 length of entire pleotelson, apex broadly rounded.

Antennula articles 1 and 2 of equal length ( Fig. 12 habitus; these articles foreshortened in Fig. 12 au), 1 slightly wider than 2, tubular, 1 and 2 combined reaching to about apex of eyestalk; articles 3, 5 and 6 of subequal length, all approximately 1/3 longer than 4.

Antenna (both antennae broken after peduncle article 4). Article 2 as wide as long, round, approximately twice length of 1; article 3 length 3.4 width, cylindrical.

Pereopod I basis length 4.7 width; ischium 0.8 length of basis, mid-anterior margin with single short spine; carpus narrowly oval, robust setae on posterior margin with small translucent flanges either side and in middle; propodus narrowing distally to insertion of dactylus, with 2 robust setae on opposing margin and small translucent flanges either side of and in the middle between robust setae. Pereopod II slender; propodus with 3 slender robust setae on posterior margin.

Pleopod II (operculum) ovoid with slightly concave distal margins, width 0.74 length.

Uropods recessed into low protruding cuticle tubes with denticulate rim; protopod hidden; exopod vestigial, hidden, with 2 setae protruding; endopod length 1.8 width.

Size. Largest female, 2.9 mm.

Distribution. South-western Pacific, Kermadec Trench, 5340-5230 meters.

Figures

FIGURE 12. Pentaceration kermadecia sp. nov. Holotype, Ƥ. a, antenna; au, antennula; cv, head, ventral view; op, operculum (pleopod 2); p 1 – 2, pereopods 1 (p 1 enl, enlarged) and 2; up, uropod. Habitus scale: 0.5 mm.

FIGURE 13. Pentaceration kermadecia sp. nov. Holotype, Ƥ. ll, lower lip; md l, left mandible; mx 1 – 2, maxilla 1 and 2; mxp, maxilliped; pl 3 – 5, pleopods 3 – 5.