Pentaceration dentifera, 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 : 26-27

Pentaceration dentifera sp. nov.

Figures 17–18

Type fixation. Holotype, male, here designated.

Etymology. The epithet reflects the highly regular, dense fringe of denticles on head and pereonite spines.

Material examined. Holotype, 3, 1.85 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 60498.

Paratypes (7 specimens). Same data as holotype, NIWA 60499 (4 ovigerous Ƥ including ƤA, 2 young Ƥ, 13).

Description (adult male, holotype). Body very flat, tapering from pereonite 1 to pleotelson; width 0.40 length, widest between pereonites 1 and 2. Head length 0.68 width; length posterior to eyestalks 1.0 anterior length. Frontal margin mid spine as long as head and half pereonite 1 combined; lateral spines slightly longer and broader than mid spine, nearly straight, diverging at 105°; all 3 head spines with regularly denticulate margins. Eyestalks straight, just overreaching pereonite 1, pointing forward at 20º, apex rounded with tiny protruding point; few ocelli present.

Pereonite 1 lateral margins convex, widest anterolaterally; pereonites 2 and 3 lateral spines diverging at 35°; pereonites 2, 3 and 5 lateral spines of similar size, 2 pointing forward at approximately 50° to body mid line, 3 and 5 pointing nearly directly laterad; pereonite 4 with tiny lateral point; pereonite 6 lateral spine the longest, pointing backwards at 35° to mid line; pereonite 7 lateral spines approximately 0.33 length of 6, pointing backwards as in 6, with tiny apical point. Pereonites 1–3 and 5–6 with regularly denticulate margins.

Pleon length 1.35 width. Pleonite 1 width 0.6 distance between uropods, length 0.25 width. Pleotelson proximally concave, merging evenly into convex lateral margins with 15–18 denticles; distal projection narrowly triangular at 50°, 0.30 length of entire pleotelson, apex broadly rounded.

Antennula and Antenna (see Female, below).

Pereopod I basis length 3.47 times width; ischium 0.6 length of basis; carpus narrowly oval, distal posterior margin weakly concave; propodus narrowing distally to insertion of dactylus, with 2 robust setae on opposing margin. Pereopod II propodus with 3 slender robust setae on posterior margin.

Pleopod I lateral sublobes unequal, distal lobe elongate, broadly rounded, nearly hiding small triangular proximal lobe; width 0.35 distance to midline; distal projection length 0.30 pleopod total length, forming acute angle, with bluntly rounded apices. Pleopod II protopod rounded distally, lateral margin with simple setae; endopod article 2 (stylet) forming curve of approximately 135°.

Uropods recessed into simple cuticle fold, in groove bordered medially by denticulate ridge; protopod and exopod not observed; endopod length 2.6 width.

Female (ovigerous). Similar to male, though pereon somewhat vaulted. Antennula articles 1 and 2 combined reaching to apex of eyestalks; articles 1 and 2 of subequal length, 1 broader than 2, tubular; 3 and 4 of equal length, 2/3 length of equal length 5 and 6. Antenna article 2 in ventral view at least four times length of barely visible article 1; 3 width 0.25 length; 5 length 3.6 times 4; 6 1.8 length of 5; first and second flagellar articles of equal length. Pereopod I as shown in male. Pereonite 1 shoulders less well developed. Head spines and pereonites 2–3 lateral spines slightly shorter and broader than in male. Operculum (pleopod II) ovoid with slightly concave distal margins; width 0.7 length, apex rounded.

Size. Largest female, 2.1 mm; largest male, 1.85 mm.

Distribution. Eastern New Zealand, 306 m.

Figures

FIGURE 17. Pentaceration dentifera sp. nov. Holotype, 3, except F, paratype, ƤA. op, operculum (pleopod 2); pl 1 – 2, pleopods 1 and 2; up, uropod. Habitus scale: 0.5 mm.

FIGURE 18. Pentaceration dentifera sp. nov. Holotype, 3, except F, paratype, ƤA. a, antenna; au, antennula; cv, head ventral view; p 1 – 2, pereopods 1 and 2.