Tanaopsis boonwurrungi, Błażewicz-Paszkowycz & Bamber, 2012

Błażewicz-Paszkowycz, M. & Bamber, R. N., 2012, The Shallow-water Tanaidacea (Arthropoda: Malacostraca: Peracarida) of the Bass Strait, Victoria, Australia (other than the Tanaidae), Memoirs of Museum Victoria 69, pp. 1-235 : 211-212

Tanaopsis boonwurrungi sp. nov.

Figures 141–143

Material examined. 1 (J57793), holotype, 1 (J58563), paratype, dissected, Western Port , off Crib Point, Stn CPBS-N 03 , 38º20.57'S 145º15.08'E, 2 m depth, fine sand, 05 April 1965; 1 (J57792) , paratype, Western Port , off Crib Point, Stn CPBS 31 N, 38º20.93'S 145º13.62'E, 15 m depth, fine sand with mud, 29 March 1965; all coll. A.J. Gilmour.

Description of female. Body ( Fig. 141) slender with widened pleon, holotype 3 mm long, 8.7 times as long as wide. Cephalothorax pear-shaped, widest and laterally-rounded posteriorly, tapering towards anterior with slight rounded rostrum, as long as maximum width, shorter than pereonites 1 and 2 together, naked; eyelobes present, eyes apparently absent in preserved material. Pereonite 1 shortest, 0.4 times as long as cephalothorax, laterally convex; pereonite 2 nearly twice as long as pereonite 1, laterally convex; pereonite 3 (and subsequent pereonites) with parallel sides, 2.5 times as long as pereonite 1; pereonite 4 longest, longer than wide and 3.2 times as long as pereonite 1; pereonite 5 just shorter than pereonite 4, pereonite 6 just longer than pereonite 2 (all pereonites respectively 2.3, 1.4, 1.0, 0.8, 0.9 and 1.2 times as wide as long). Pleon with five free pleonites bearing pleopods; first pleonite trapezoidal, longest, as long as pereonite 1 and 2.7 times as long as wide; each remaining pleonite 0.8 times as long as first pleonite and 3.9 times as wide as long. Pleotelson pentangular, one-quarter length of pleon and 1.7 times as wide as long, with two slender distal spines.

Antennule ( Fig. 142A) of five articles (four longer articles plus minute distal article), proximal article 2.1 times as long as wide, just shorter than distal four articles together, outer margin with tufts of three penicillate setae at mid-length and two penicillate and one simple setae distally; second article as long as wide, 0.35 times as long as first article, distally with single inner and outer simple setae and three penicillate setae; third article compact, 0.7 times as long as second article, distally with single inner and outer simple setae; fourth article tapering, nearly twice as long as third article, with single simple distal seta; fifth article ( Fig. 142 A') minute, with aesthetasc and four simple and one penicillate distal setae.

Antenna ( Fig. 142B) of six articles, proximal two articles not recovered; third article longer than wide, with fine dorsodistal seta longer than article and distal microtrichia; fourth article longest, 2.7 times as long as third article, 4.5 times as long as wide, slightly curved, with three simple and three penicillate distal setae; fifth article as long as third with one distal seta; sixth article minute with five distal setae.

Labrum not recovered. Mandibles ( Fig. 142C) without lacinia mobilis or pars molaris, pars incisiva with saw-like row of denticulations and rounded distal apophysis, larger on right mandible. Labium ( Fig. 142F) with prominent, finely setulose mediodistal processes. Maxillule ( Fig. 142D) with five finely-denticulate distal spines, one stouter than the others, and outer tufts of setules, palp not recovered. Maxilla ( Fig. 142E) linguiform but basally cupped, with fine marginal setules. Maxilliped palp ( Fig. 142G) first article naked, second article with one outer and one inner distal setae; third article with four slender and curved inner setae; fourth with five distal setae and one outer subdistal seta; basis with single seta reaching distal margin of proximal palp article; endite distally naked. Epignath ( Fig. 142H) elongate, linguiform, naked.

Cheliped ( Fig. 143A) basis 1.6 times as long as wide, naked; merus subtriangular with single ventral seta; carpus stout, 1.2 times as long as wide, with two midventral setae, one mid-dorsal and one dorsodistal setae; propodus stout, as long as wide, fixed finger 0.6 times as long as palm, with two ventral setae, three setae on cutting edge, distal claw with typical inner and outer bifurcate apophyses; dactylus dorsally finely crenulate, with slender spinules along cutting edge and fine proximal seta.

Pereopod 1 ( Fig. 143B) longer than others, coxal apophysis ( Fig. 143 B') large, pointed, with seta; basis slender, 5.7 times as long as wide, naked; ischium compact, naked; merus 0.7 times as long as carpus, wider distally, naked; carpus with single dorsal and ventral distal setae; propodus 1.7 times as long as carpus, with three dorsal subdistal setae, one ventral subdistal seta; dactylus half as long as unguis, unguis slender and as long as propodus. Pereopod 2 ( Fig. 143C), coxa rounded with seta; basis 4.3 times as long as wide; ischium with seta; merus 0.7 times as long as carpus, with single ventrodistal seta; carpus with two dorsal and one ventral distal setae; propodus 2.2 times as long as carpus, with two dorsal subdistal setae, one ventral subdistal seta; slender unguis longer than dactylus, both together 1.2 times as long as propodus. Pereopod 3 ( Fig. 143D) similar to pereopod 2.

Pereopod 4 ( Fig. 143E) basis stout, 2.1 times as long as wide, naked; ischium with two ventrodistal setae; merus as long as carpus, with ventral field of microtrichia and two small distally-denticulate ventrodistal spines; carpus with one dorsodistal seta and three small distally-denticulate ventrodistal spines; propodus 1.6 times as long as carpus, with fields of microtrichia, mid-dorsal penicillate seta, one dorsodistal and two ventrodistal spines all distally finely denticulate; dactylus slender, with fields of microtrichia, 1.5 times as long as unguis, both together 0.9 times as long as propodus. Pereopod 5 ( Fig. 143F) as pereopod 4, but basis with two ventral penicillate setae. Pereopod 6 ( Fig. 143G) as pereopod 4, but propodus with three dorsodistal spines.

Pleopods ( Fig. 143H) all alike, with naked basis, endopod shorter than exopod and with rounded proximal apophysis on inner margin; endopod with inner subdistal plumose seta and 14 plumose setae along the distal half of the outer margin, exopod without setae on inner margin, outer margin with 27 plumose setae, proximal setae on rami not separated from others.

Uropod ( Fig. 143I) biramous, basis naked; exopod and endopod each of one segment, exopod shorter than endopod, with one fine proximal, one shorter and one longer distal setae; endopod with distal penicillate seta on first segment and five simple and one penicillate distal setae on second segment.

Male. Unknown.

Etymology. The Boonwurrung were another of the indigenous hunter-gatherer tribes of the (now) Melbourne region in the mid-nineteenth century (see under Paragathotanais wurundjeri above).

Remarks. Sieg and Dojiri (1991) gave a key to the genus Tanaopsis for the species then known, in which the present species keys out to the generotype, T. graciloides with which they included T. laticaudata as a synonym (as had most previous authors). Bamber et al. (2009) cast doubt on this synonymy, maintaining the distinction of Sars’ Mediterranean species from Lilljeborg’s Northeast Atlantic-Subarctic species until a proper redescription of the latter was undertaken; all descriptions and figures referred to in the recent literature for T. graciloides , including by Sieg and Dojiri (1991) are from Sars (1882). Bird & Bamber (2000), while describing as new T. chotkarakde , also added T. gallardoi to the genus. Since then, the only new Tanaopsis species that have been described are T. canaipa from Queensland and T. rawhitia Bird, 2011 from New Zealand.

Tanaopsis boonwurrungi sp. nov. shares the lack of a molar process on the mandible only with T. graciloides / laticaudata and T. chotkarakde , and possibly T. kerguelenensis (mandible not described, but a species also with one-segmented uropodal rami). T. boonwurrungi is immediately distinguished from all of these taxa by its distinctly more slender habitus, with pereonites 4 and 5 longer than wide, and a much more slender cheliped, while T. chotkarakde has a lacinia mobilis on the left mandible, and the two European taxa have a two-segmented uropod exopod.

The small distal article on the antennule has only been reported before for a Tanaopsis species by Bird (2011), who noted its presence in T. rawhitia . While such an article does not appear to have been present in some other more recently or better-described species, viz. T. kerguelenensis , T. cadieni , T. chotkarakde or T. canaipa , the possibility of its having been overlooked in some of the earlier descriptions cannot be dismissed.

Tanaopsis boonwurrungi was taken only in Western Port at 2 to 15 m depth on fine sand.