Pentaceration curvicornis, 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 : 7-10

Pentaceration curvicornis sp. nov.

Figures 4–5

Type fixation. Holotype, female, here designated.

Etymology. The epithet alludes to the curved lateral head spines.

Material examined. Holotype, spent Ƥ, 2.35 mm, New Zealand, east coast, 41°04.10'S, 176°22.05'E, 306 m, ring net on trawl warp, 23 February 2000, RV Kaharoa, cruise KAH0001, stn 79, NIWA 60500. Paratypes (10 specimens). Same data as holotype, NIWA 60501 (3A, 1.82 mm). Same data as holotype, NIWA 60502 (2 spent Ƥ). Same data as holotype, NIWA 60503 (5 Ƥ, 2 3).

Description (spent females). Body tapering towards pleon; width 0.38 length, widest between pereonites 2 and 3. Head length 0.18 width; length posterior to eyestalks equal to anterior length. Frontal margin mid-spine slender, pointed, length equals combined length of head and half length of pereonites 1; lateral spines equal length of midspine, curved backwards, distally up-curved, diverging at 95°. Eyestalks overreaching pereonite 1 by about half their length, pointing forward at 10°, slender, pointed, distally up-curved.

Pereonites all with single slender, upright mid-dorsal spine. Pereonite 1 lateral margins rounded, irregularly denticulate; pereonite 2 and 3 lateral spines diverging at 30°, with slender, up-curved irregularly denticulate spines, length approximately 0.25 pereonite width, margins either side of spine with single anterior denticle, posteriorly with 2 and 1 spines respectively; pereonite 4 with short, pointed lateral spines; 5–7 lateral spines subsimilar to 2 and 3 but narrower; 5 up-curved, with strong denticle on proximoposterior margin; 6 and 7 with proximoanterior lobe, 6 with strong denticle on proximoposterior margin; 5 and 6 with short row of setae on overlapping posterior bulges.

Pleon length 1.35 width. Pleonite 1 width 0.85 distance between uropods, length approximately 0.1 width. Pleotelson with distinct neck, proximal and lateral margins forming evenly merging curve, lateral margins convex, with 9–10 denticles, distal projection narrowly triangular at approximately 55°, 0.36 length of entire pleotelson, with rows of lateral simple setae, apex pointed.

Antennula article 1 approximately 0.7 length of 2, wider than 2, tubular; 2 reaching apex of eyestalks, as long as 3–6 combined, 3–4 subequal, 0.6 length of equal 5 and 6.

Antenna article 2 about 9 times length of 1, broad with convex lateral margin; article 3 width 0.2 length, with small acute spine distolaterally; article 5 4.4 length of 4; 6 twice length of 5; 6 1.5 length of 5; flagellum articles 1 and 2 slender, 1 approximately 1.2 length of 2.

Pereopod I basis length 3.3 width, with row of acute, curved spines anterodistally; ischium 0.75 length of basis, with single acute, curved spine on anterior margin; merus with single acute spine on anterior margin; carpus narrowly oval with nearly parallel anterior and posterior margins; propodus narrowing distally to insertion of dactylus, with 2 robust setae on opposing margin. Pereopod II basis with anterodistal row of acute spines, propodus with single posterodistal robust seta.

Pleopod II (operculum) ovoid with pointed apex, distal margins weakly concave, width 0.66 length, (marginal simple setae not observed).

Uropods recessed into simple cuticle fold, protopod and exopod apparently absent; endopod length 5.3 width.

Male. Similar to female, but head spines and pereonites 1 and 2 lateral spines longer and more robust than in female, the latter spines lacking strong denticles around base. Pleotelson posterior projection longer than in female. Pleopod I proximal lateral sublobe dominant, broadly rounded, completely overlapping smaller, rounded distal sublobe; width 0.27 distance to midline; distal projection length 0.37 pleopod total length, forming narrowly acute angle, with pointed apices. Pleopod II protopod rounded distally, lateral margin with simple setae; endopod article 2 (stylet) forming approximately 170° curve.

Size. Largest female (spent), 2.35 mm; largest male, 1.82 mm.

Distribution. Eastern New Zealand, 306 m.

Figures

FIGURE 4. Pentaceration curvicornis sp. nov. Holotype, Ƥ; except F, paratype Ƥ, and M, paratype 3 A. a, antenna; au, antennula; cv, head ventral view; up, uropod. Habitus scales: 0.5 mm.

FIGURE 5. Pentaceration curvicornis sp. nov. Holotype, Ƥ; except M, paratype 3 A. op, operculum (pleopod 2); p 1 – 2, pereopods 1 and 2 (not to scale); pl 1 – 2, pleopods 1 and 2.