Pentaceration, an unusual new genus of Paramunnidae from Australia (Isopoda, Asellota) Author Just, Jean text Zootaxa 2009 2134 36 48 journal article 10.5281/zenodo.188472 bc0f2861-3a79-41b1-969d-797fa4b0ce8c 1175-5326 188472 Pentaceration bassiana sp. nov. Figs 1–4 Type fixation . Holotype , male, here designated; Museum Victoria: NMV 20091. Etymology . The epithet denotes the wide distribution of the species in the Bass Strait. Material examined. Holotype , 3, 1.4 mm , Australia , central Bass Strait, 20 km NNE of North Point, 40o38.0'S , 145o23'E , 36 m , muddy shell grit, Smith-McIntyre grab, M.F. Gomon & G.C.B. Poore, RV Sarda , stn BSS 117, 4 November 1980 , Museum Victoria, NMV J20091 (with 2 slides). Paratypes . (South-eastern Australia , Bass Strait, 48 specimens ). 48 km WNW of Stokes Point, King Island, 40o4.00'S , 143o22.00'E , 108 m , coarse sand, carbonate, Smith-McIntyre grab, G.C.B. Poore, HMAS Kimbla , stn BSS 89, 11 October 1980 , NMV J20086 (1 ovigerous Ƥ). 70 km W of Cape Farewell, King Island, 39o38.2'S , 143o07.2'E , 127 m , mainly sand, R.S. Wilson, RV Tangaroa , stn BSS 195, 21 November 1981 , NMV J20087 (1 preparatory Ƥ). 23 km E of Cape Rochon, Three Hummock Island, 40o22.2'S , 145o17'E , 40 m , mainly sand, epibenthic dredge, M.F. Gomon & G.C.B. Poore, RV Sarda , stn BSS 112, 3 November 1980 , NMV J20088 (1 young 3, 1 near terminal 3). 20 km NNE of North Point, 40o32.0'S , 145o23'E , 43 m , muddy shell grit, Smith-McIntyre grab, M.F. Gomon & G.C.B. Poore, RV Sarda , stn BSS 116, 4 November 1980 , NMV J20089 (1 preparatory Ƥ). 20 km NNE of North Point, 40o38.0'S , 145o23'E , 36 m , muddy shell grit, epibenthic sled, M.F. Gomon & G.C.B. Poore, RV Sarda , stn BSS 117, 4 November 1980 , NMV J20090 (1 ovigerous Ƥ). 5 km SW of Bluff Point, 40o48.1'S , 144o38.0'E , 42 m , bryozoans, Smith- McIntyre grab, M.F. Gomon et al ., RV Hai Kung, stn BSS 126, 2 February 1981 , NMV J20092 (1 preparatory Ƥ). 38 km SW of Cape Paterson, 38o55.5'S , 145o17.0'E , 70 m , fine sand, R.S. Wilson, RV Tangaroa , stn BSS 155, 12 November 1981 , NMV J20093 (1 ovigerous Ƥ). 38 km SW of Cape Paterson, 38o55.5'S , 145o17.0'E , 70 m , fine sand, R.S. Wilson, RV Tangaroa , stn BSS 155, 12 November 1981 , NMV J20094 (4 ovigerous ƤƤ). 66 km S of Rodondo Island, 39o48.6'S , 146o18.8'E , 82 m , sand, silt and mud, R.S. Wilson, RV Tangaroa , stn BSS 158, 13 November 1981 , NMV J20096 (1 terminal 3). 66 km S of Rodondo Island, 39o48.6'S , 146o18.8'E , 82 m , sand, silt and mud, epibenthic sled, R.S. Wilson, RV Tangaroa , stn BSS 158, 13 November 1981 , NMV J20097 (1 small 3, 1 ovigerous Ƥ). 66 km S of Rodondo Island, 39o48.6'S , 146o18.8'E , 82 m , sand, silt and mud, R.S. Wilson, RV Tangaroa , stn BSS 158, 13 November 1981 , NMV J20098 ( 4 33, 16 ƤƤ ovigerous and preparatory, including Ƥ Fig. 1 F). 57 km S of Rodondo Island, 39o43.5'S , 146o18.8'E , 80 m , muddy shell, Smith-McIntyre grab, R.S. Wilson, RV Tangaroa , stn BSS 159, 13 November 1981 , NMV J20099 ( 3 33, 4 preparatory ƤƤ). 57 km S of Rodondo Island, 39o43.5'S , 146o18.8'E , 80 m , muddy shell, R.S. Wilson, RV Tangaroa , stn BSS 159, 13 November 1981 , NMV J20100 ( 1 specimen ). 50 km SE of Port Albert, 38o54.3'S , 147o13.4'E , 58 m , coarse shell, R.S. Wilson, RV Tangaroa , stn BSS 176, 18 November 1981 , NMV J20101 (1 ovigerous Ƥ). 40 km SSW of Lakes Entrance, 38o18.0'S , 147o37.0'E , 55 m , muddy fine shell, trawl or sled, M.F. Gomon & R.S. Wilson, FV Silver Gull , stn BSS 209, 31 July 1983 , NMV J20102 (1 ovigerous Ƥ). Maria Island 2 km E of Cape Boulanger, 42o34.00'S , 148o6.00'E , 50 m , fine Bryozoa and shell, epibenthic sled, R.S. Wilson, RV Challenger , stn TAS 29, 23 April 1985 , NMV J20104 (1 preparatory Ƥ). E of Maria Island, 42o36.00'S , 148o10.00'E , 75 m , fine bryozoans and shell, epibenthic sled, R.S. Wilson, RV Challenger , stn TAS 30, 23 April 1985 , NMV J20105 (2 preparatory ƤƤ). Description (adult male, holotype ). Body elongate ovate, slightly tapering towards pleon; width 0.35 length, widest between pereonites 1 and 2. Head length 0.35 width; length posterior to eyestalks 1.20 anterior length. Frontal margin mid-spine length subequal to head length, with minutely truncate apex, margins serrate; lateral spines as long as mid-spine, straight, with coarse marginal denticles. Eyestalks overreaching pereonite 1 by about half their length, pointing laterad at approximately 90º to head midline, anterior and posterior margins parallel or slightly expanding distally, apex rounded, distally microserrate; with a few ocelli. Pereonites 1–5 and 7 of equal mid-length, 6 slightly longer; pereonite 1 dorsolaterally with moderately inflated ‘shoulders’; pereonites 1–7 with single short conical mid-dorsal spine. Pereonite 1 lateral margins irregularly rounded truncate with short irregular denticles; pereonite 2 with broad marginally denticulate spine as long as half pereonite width; pereonite 3 with short pointed spine a little less than half pereonite 2 spine length; pereonite 4 with pointed spine approximately 0.25 length of pereonite 3 spine; pereonites 5–6 lateral spines similar to pereonite 2; pereonite 7 with spine similar to pereonite 4 spine. Pereonites 6 and 7 with tumaculae arising from ventrolateral anterior surfaces of pereonite, projecting into cavity between adjoining pereonites. Pleon length equal to width. Pleonite 1 with single dorsal spine; width 0.54 distance between uropods, length 0.2 width. Pleotelson with short proximal neck; dorsal surface at neck with single rounded spine; proximal and lateral margins forming distinct angle, lateral margins diverging distally, with approximately 20 denticles, mid-laterally concave, distally forming projecting corners with hook-like denticle pointing mediad, reaching as far back as posterior margin, producing deep concavities either side of posterior margin; posterior margin broad, triangular at 70°, apex rounded, 0.25 length of entire pleotelson. Antennula articles 1 and 2 combined reaching about 2/3 along eyestalk; article 1 shorter and slightly wider than 2, tubular; 3 and 4 of equal length, both 2/3 length of subequal 5 and 6. FIGURE 1 . Pentaceration bassiana gen. et sp. nov. Holotype, male, except F , paratype, ovigerous female (NMV J20098 ). a , antenna; au , antennula; cv , head ventral view; pe , pereonite, lateral parts, tumaculum in pocket between pereonites shown; up , uropod. Scale bars for habitus figures: 0.5 mm. Antenna article 2 in ventral view approximately four times length of 1; 3 width 0.3 length, narrowing in distal 1/3; 5 length 2.6 times 4; 6 length 1.6 of 5; flagellum with 9 articles, proximal article 1.2 length of second article. Pereopod I basis length 4 times width; ischium half length of basis, anterior margin with single acute spine; carpus oval, distal margin width 1.3 posterior margin length, distal margin weakly concave, distal robust seta with small hyaline flanges at base; propodus narrowing distally to insertion of dactylus, with 2 robust setae on opposing margin. Pereopods II–VII propodus with 1–2 slender robust setae on posterior margin. Pleopod I lateral sublobes overlapping, proximal one broadly rounded, distal one more angular; width 0.26 distance to midline; distal projection length 0.28 pleopod total length, forming acute angle, with pointed apices. Pleopod II protopod bluntly rounded distally, lateral margin with simple setae; endopod article 2 (stylet) forming 130° curve. Uropods recessed into protruding cuticle tube with large mediodistal projection, reaching to apex of endopod; exopod vestigial with single simple seta. FIGURE 2 . Pentaceration bassiana Holotype, male., mandible (, left; r , right); mx 1–2 , maxilla 1 and 2; mxp , maxilliped. Variation . Males appear to become terminal at a larger size than the holotype . Terminal males differ from the holotype in the somewhat more bulky shoulders and a different pereopod I. While pereopod I of the holotype is broadly similar to that of females, males of 1.7–1.8 mm from the type locality have a more rectangular carpus with the proximal half of the posterior margin projecting, and 1 large and 1 smaller blunt spines just distal to the distalmost robust seta. Pereopod I from a 1.78 mm specimen ( Fig. 3 M) has 2 blunt anterodistal spines on basis, a single similar mid-anterior spine on ischium, 1 anterior and 2 posterior acutely pointed spines on merus, and a small posterodistal denticle on propodus. The pattern of pereopod I spines differ among terminal males with some spines occasionally lacking. Females. Females are similar to males in general body shape, although ovigerous females are wider relative to length: 0.42, have less strongly developed pereonite 1 lateral parts, and with a more bulging pereon. Head length/width is 0.28, length posterior to eyestalks 1.4 anterior length. Head frontal margin spines are shorter than in males relative to eyestalks. Lateral spines on pereonite 3 are equal to those of pereonite 2. Pereopod I carpus is narrow oval; propodus has a single robust seta on opposing margin in specimens examined. The operculum is ovoid with slightly concave distal margins, width 0.68 length. FIGURE 3 . Pentaceration bassiana gen. et sp. nov. Holotype, male, except F, paratype, ovigerous female, and M , paratype, terminal male. p1, 2 and 6 , pereopods 1, 2 and 6. FIGURE 4 . Pentaceration bassiana gen. et sp. nov. Holotype, male, except op , paratype, ovigerous female, and a–d , paratype females. op , operculum; pl1–4 , pleopods 1–4 ( *, tip of pleopod 2 stylet); pt , pleotelson; vv , ventral view; a–d , lateral view of dorsal armature in 4 paratype females, a–c , ovigerous, d , preparatory. General variation . Mid-dorsal spines in both sexes vary in size and shape from low humps to irregular spines ( Fig. 4 a–d). The mid-cephalic spine may be somewhat shorter than the lateral ones, and all three cephalic spines vary between straight and moderately downward curved. Size . Largest male (terminal), 1.8 mm ; largest ovigerous female, 2.1 mm . Distribution. Australia , Bass Strait, 36– 127 m .