Poorea wrighti, Edgar, Graham J., 2012

Edgar, Graham J., 2012, New Leptocheliidae (Crustacea: Tanaidacea: Tanaidomorpha) from Australian seagrass and macro-algal habitats, and a redescription of the poorly-known Leptochelia ignota from Sydney Harbour, Zootaxa 3276, pp. 1-37 : 19-23

Poorea wrighti n. sp.

( Figs 10–11 )

Material examined. Holotype. Male ( NMV J62318 ), 2.1 mm, Cliff Head, WA (29.52°S 114.99°E), 1 m depth, seagrass ( Amphibolis antarctica ) washings, 4 December 1986.

Paratypes. Three males ( NMV J62319 ), Seven Mile Beach, WA (29.17°S 114.89°E), 1 m depth, seagrass ( Amphibolis antarctica and A. griffithii ) washings, June 1985 – June 1987.

Other material. Six males, ( NMV J62320 ) Bickley Point, Rottnest Island, WA (32.00°S 115.56°E), seagrass washings, 0.5 m depth, 10 Jan 1991.

Description. MALE. Body ( Fig. 10 ). Observed length 1.3–2.1 mm; red colouration when freshly preserved; body about eight times longer than broad; cephalothorax subrectangular, laterally slightly convex, approximately one-sixth body length; eyes very large, ovoid, about one-third length of cephalothorax.

Pereon just over half total length; pereonite-1 length about one-third width; pereonites 2 and 3 similar, about 1.5 times length of pereonite-1, length about half width; pereonite 4 and 5 similar, about 1.3 times length of pereonite-3, length about two-thirds width; pereonite-6 equal in length to pereonite-3, length about twice width.

Pleonites 1–5 similar other than declining in width posteriorly with pleonite 5 five-sixths width of pleonite-1, together one-fifth as long as body.

Pleotelson about 1.2 times length of pleonite 5; posterior margin with paired central medium-length and minute setae, posterior pair of setae (one minute) and anterior seta on each lateral margin.

Antennule ( Fig. 10 ). One-third length of body, article-1 about three times longer than wide, with distal group of three small plumose setae; article-2 about two-thirds length of article-1, length about twice width; article-3 length about half article-2; articles 4–10 comprising flagellum that extends almost one-third of total antennule length, article-4 with six proximal aesthetascs and four distal aesthetascs, articles 5 and 6 with four distal aesthetascs, articles 7 and 8 with three distal aesthetascs, article 9 with two distal aesthetascs, terminal article minute with two aesthetascs.

Antenna ( Fig. 10 ). Six articles, together slightly less than half length of antennule; article-1 wider than long, lacking setae; article-2 length two-thirds width, with three small simple setae distally; article-3 half length of article-2, with distal seta; article-4 about five times longer than article-3, with two long simple setae distally; article-5 about half length of article-4, length three times width, with a long seta distally; article-6 reduced to small terminal cap, with two simple setae, the longest extending about two-thirds total length of antennule.

Mouthparts reduced and fused.

Cheliped ( Fig. 10 ). Length about one-third total body length; basis length 1.3 times width; merus triangular with two setae; carpus about two-fifths length of cheliped, length 1.5 times width, with three ventral setae; propodus palm similar in width to carpus, inner comb-like row of about 15 setae of similar length near articulation with dactylus, fixed finger similar in length to palm, with blunt apophysis two-thirds distance along inner margin, six distal setae, small terminal spine; dactylus similar in length to fixed finger, inner margin with four minor indentations and five setae, outer margin with single proximal seta; unguis small, about one-tenth of total propodus length.

Pereopod-1 ( Fig. 11 ). Basis width one-third length, length 1.2 times length of merus and carpus together, with two setae about one-quarter distance along dorsal margin; ischium with one small ventral seta; merus just over onethird length of basis, without setae; carpus three-quarters length of merus with about five distal setae; propodus length similar to merus and carpus together, with four long distal setae three-quarters distance to distal margin; dactylus and unguis together about two-thirds length of propodus, unguis about two-thirds length of dactylus.

Pereopods 2 and 3 ( Fig. 11 ). Similar; basis width about one-third length, length 1.6 times length of merus and carpus together, with two setae about one-third distance along dorsal margin; ischium with small ventro-distal seta; merus just over one-quarter length of basis, with spiniform seta and simple seta distally; carpus similar in length to merus, with two spiniform setae and a simple seta distally; propodus twice length of carpus, with spiniform seta and two simple setae three-quarters distance to distal margin; dactylus and unguis together about half length of propodus, unguis about half length of dactylus.

Pereopods 4 and 5 ( Fig. 11 ). Similar; basis width about one-third length, length 1.5 times length of merus and carpus together; ischium with ventro-distal seta; merus one-third length of basis, with two spiniform setae distally; carpus similar in length and width to merus, with three spiniform setae near distal margin; propodus 1.3 times length of carpus, with two spiniform setae three-quarters distance to distal margin and two simple setae dorso-distally; dactylus and unguis partially fused into claw, together two-thirds length of propodus, unguis about half length of dactylus.

Pereopod-6 ( Fig. 11 ). Basis width about one-third length, length 1.5 times length of merus and carpus together; ischium with two ventro-distal setae; merus one-third length of basis, with spiniform seta distally; carpus 1.2 time length of merus, with three spiniform setae near distal margin; propodus 1.3 times length of carpus, with two spiniform setae and five simple setae near distal margin; dactylus and unguis together two-thirds length of propodus, unguis about one-quarter length of dactylus.

Pleopods 1–5 ( Fig. 11 ). Basal article length equal to width; exopod relatively narrow, length one-third width, with about 19 plumose setae on inner margin; endopod length about three times width, with about 14 plumose setae on inner margin, plumose seta midway along outer margin.

Uropod ( Fig. 11 ). Basal article length twice width, with two distal setae; exopod with short article, length about half length of endopod article-1, with three long terminal setae that extend to end of endopod article-2; endopod with three articles.

Etymology. This species is named in memory of David Wright, CSIRO senior technician, who generously assisted with field surveys at the type location.

Distribution. Rottnest Island to Dongara, WA.

Remarks. This species can be distinguished from other Poorea species by the presence of a large round protuberance two-thirds distance along the inner margin of the fixed finger of the male cheliped, and on uropod shape, with the endopod formed from three articles and the exopod extending half distance along endopod article-1. Poorea wrighti n. sp. shows closest morphological affinity within the known Australian fauna with P. nobbi ( Bamber, 2005) from Albany, WA; however, amongst other features, P. nobbi has more compact chelipeds that include a Paratanais -like merus that extends full distance rather than halfway along carpus, fixed finger as wide as long rather than longer than wide, and fewer and smaller spiniform setae on pereopods 2–6.

Figures

FIGURE 10. Poorea wrighti. Cliff Head, WA. Male dorsal (holotype), antennule (A 1), antenna (A 2), cheliped (CH), pleotelson (Plt). Scale units 0.1 mm for full appendages.

FIGURE 11. Poorea wrighti. Cliff Head, WA. Male. Pereopods 1 – 6 (P 1 – P 6), pleopod (Pl), uropod (U). Scale units 0.1 mm for full appendages.