Pentaceration simplex, 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 : 37-40

Pentaceration simplex sp. nov.

Figures 26–27

Type fixation. Holotype, male, here designated.

Etymology. The epithet indicates that this species mostly exhibits basic characters of the genus.

Material examined. Holotype, 3, 1.53 mm, Australia, Victoria, South of Point Hicks, 38o17.70'S 149o11.30'E, 400 m, coarse sand, gravel, mud, many sponges, WHOI epibenthic sled, M. F. Gomon et al, RV Franklin, 24 July 1986, stn SL 40, NMV J20061 (with 3 slides).

Paratypes (10 specimens). Australia, New South Wales, Off Nowra, 34o57.90'S, 151o8.00'E, 503 m, Bryozoa and shell, WHOI epibenthic sled, G.C.B. Poore, et al, RV Franklin, 14 July 1986. stn SL 2, NMV J20058 (1 Ƥ). Australia, New South Wales, Off Eden, 37o0.60'S, 150o20.70'E, 363 m, coarse shell, WHOI epibenthic sled, G.C.B. Poore, et al, RV Franklin, 21 July 1986, stn SL 22, NMV J20059 (ƤA, ovigerous, 1.68 mm, illustrated, plus 2 smaller Ƥ). Same data as holotype, NMV J20060 (2 3, 2 preparatory Ƥ). Same data as holotype, NMV J20062 (1 Ƥ cleared in lactic acid). Australia, Tasmania, of Freycinet Peninsula, 41o57.50'S, 148o37.90'E, 400 m, coarse shell, WHOI epibenthic sled, M.F. Gomon et al, RV Franklin, 27 July 1986, stn SL48, NMV J20064 (1 preparatory Ƥ). Australia, Victoria, 76 km S of Point Hicks, 38o29.33'S, 149o19.98'E, 1840– 1750 m, sandy mud, fine shell, WHOI epibenthic sled, G.C.B. Poore et al, RV Franklin, 26 October 1988, stn SL 69, NMV J20109 (1 Ƥ).

Description (adult male, holotype). Body square; width 0.48 length, widest between pereonites 5 and 6. Head length 0.25 width; length posterior to eyestalks 1.4 anterior length. Frontal margin mid spine length 0.62 head length; lateral spines straight, twice as long and broad as middle spine, diverging at 100°; mid spine set somewhat lower on head than lateral spines, the latter tending to point upward. Eyestalks overreaching pereonite 1 with 0.25 of their length, pointing forward at 10°, apex rounded.

Pereonite 1 lateral margins rounded, weakly denticulate; pereonite 2 and 3 lateral spines diverging at 20°; pereonite 2 lateral spines similar to lateral head spines, length subequal to half pereonite width; pereonite 3 spines similar to 2, but about half as long; pereonite 4 with tiny lateral spines; pereonites 5–7 lateral spines broad, triangular, on 5 pointing lateral, on 6 and 7 successively more backwards; pereonites 5 and 6 with fringe of simple setae posterolaterally where overlapping succeeding pereonite.

Pleon length 1.2 width. Pleonite 1 width 0.65 distance between uropods, length 0.2 width. Pleotelson proximal and lateral margins meeting at wide angle, lateral margins convex, with 11–12 denticles; distal projection triangular at 80°, 0.33 length of entire pleotelson, apex pointed.

Antennula articles 1 and 2 combined reaching approximately to apex of eyestalks; articles 1 and 2 of subequal length, 2 tubular; 3 and 4 of subequal length, combined as long as 5, 6 approximately 0.85 length of 5.

Antenna article 2 in ventral view at least three to four times length of 1 (article 1 barely visible); 3 width 0.3 length; 5 length 2.75 times 4; 6 1.8 length of 5; first flagellar article 1.2 length of article 2.

Pereopod I basis length 3.4 times width; ischium 0.6 length of basis, anterior margin with single acute spine; merus with single acute spine on anterior margin; carpus oval, distal margin weakly concave, distal robust seta with rounded translucent flange in front; 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, with gap between, proximal one pointed triangular, distal one more narrow, tongue-shaped; width 0.2 distance to midline; distal projection length 0.31 pleopod total length, forming acute angle, with pointed apices. Pleopod II protopod pointed distally, lateral margin with simple setae; endopod article 2 (stylet) forming curve of approximately 200°.

Uropods recessed into low simple cuticle fold, protopod hidden, exopod apparently absent; endopod length 2 times width.

Female (ovigerous, illustrated). Body slightly tapering towards pleon. Head generally as in male, but the mid head spine more pronouncedly low-set. Pereonite 1 shoulders less well developed. Pereonite lateral spines ranging from slightly shorter and broader than in male to equally long and more pointed than in Fig. 26 F, diverging at 35°. Operculum (pleopod II) ovoid, width 0.8 length, apex rounded.

Size. Largest female, 1.68 mm; largest male, 1.53 mm.

Distribution. South-eastern Australia, 400– 500 m.

Figures

FIGURE 26. Pentaceration simplex sp. nov. H, holotype, 3. F, paratype, ƤA. p 1 – 2, pereopods 1 and 2; up, uropod. Habitus scales: 0.5 mm.

FIGURE 27. Pentaceration simplex sp. nov. Holotype, except F, paratype, ƤA. a, antenna; au, antennula; cv, head ventral