Apseudes tuski, Błażewicz-Paszkowycz & Bamber, 2007

Błażewicz-Paszkowycz, M. & Bamber, R. N., 2007, New apseudomorph tanaidaceans (Crustacea: Peracarida: Tanaidacea) from eastern Australia: Apseudidae, Whiteleggiidae, Metapseudidae and Pagurapseudidae, Memoirs of Museum Victoria 64, pp. 107-148 : 116-120

Apseudes tuski sp. nov.

Figures 4–6

Material: Female, holotype ( NMV J47119 ), 1 brooding female, Australia, Victoria, eastern Bass Strait, 43 km SE of Port Albert (38°53.42'S, 147°06.30'E), 58 m, 18/11/1981, ( BSS 177 ), R.S. Wilson; Paratypes: 37 females ( NMV J55748 ), same locality as holotype; 1 female dissected on slides ( NMV J55942 ), same locality as holotype; 2 individuals ( NMV J28577 ), eastern Bass Strait, 10.8 km E of eastern edge of Lake Tyers (37°50.55'S, 148°12.50'E), 25/09/1990, ( MSL-EG 118 ), N. Coleman; 2 individuals ( NMV J28625 ), Stn MSL-EG 58, eastern Bass Strait , 4.6 km S of Cape Conran (37°51.26'S, 148°43.44'E), 50 m, 28/09/1990, ( MSL-EG 58 ), Marine Science Laboratories; 7 individuals ( NMV J28624 ), Australia, Victoria, eastern Bass Strait , 5.3 km ESE of Pt. Ricardo (37°50.29'S, 148°40.35'E), 43 m, 28/09/1990, ( MSL-EG 54 ), Marine Science Laboratories; 2 individuals ( NMV J55781 ), Western Port , off Crib Point (38°21.10'S, 145°14.00'E), 18 m, 29/03/1965, (CPBS-0 60), A.J. Gilmour; 1 individual ( NMV J55782 ), eastern Bass Strait , 28 km SSW of Marlo (37°59'S, 148°27'E), 51 m, 30/07/1983, ( BSS 207 ), M.F. Gomon and R.S. Wilson; 2 individuals ( NMV J28623 ), eastern Bass Strait , 15.1 km WSW of Pt. Ricardo (37°51.38'S, 148°28.14'E), 34 m, 26/09/1990, ( MSL-EG 49 ); 1 individual ( NMV J28575 ), eastern Bass Strait , 11.7 km W of Pt. Ricardo (37°49.53'S, 148°30.08'E), 27 m, 02/1991, ( MSL-EG 103 ), N. Coleman; 1 ovi female, eastern Bass Strait , 8 km S of South East Point, Wilsons Promontory (39°12.54'S, 146°27.18'E), 65 m, 18/11/1981, ( BSS 180 ), R.S. Wilson; 1 hermaphroditic, 81-T-1, Stn 166, ( NMV J55784 ), eastern Bass Strait , 20 km SSW of Babel I. (40°06.48'S, 148°24.18'E), 22 m, 14/11/1981, ( BSS 166 ), R.S. Wilson; 1 ovi female, ( NMV J55785 ), western Bass Strait , 35 km SSW of Cape Otway, Victoria (39°07.00'S, 143°14.36'E), 84 m, 20/11/1981, ( BSS 183 ), R.S. Wilson .

Description of female. Body dorsoventrally flattened, elongate, holotype 5.3 mm long (tip of rostrum to posterior of pleotelson), 5.2 times as long as wide, narrower posteriorly. Cephalothorax subrectangular, slightly longer than wide, anterior margin with conspicuous but blunt rostrum with rounded “shoulders” at base. Eyes present; eyelobes rounded; no lateral spiniform apophyses at anterior margin of branchial chambers. 6 free pereonites, all without lateral spiniform apophyses; pereonite 1 shortest, about one-quarter as long as cephalothorax, pereonite 2 1.5 times as long as pereonite 1, both with lateral margins uniformly convex; pereonites 3, 4 and 6 subequal, twice as long as pereonite 1, with anterolateral indentations reflecting dorsal sculpturing and expansions over coxae of pereopods; pereonite 5 just longest, 1.2 times as long as and of similar morphology to pereonite 4 (all pereonites respectively 4.0, 2.3, 1.7, 1.6, 1.4 and 1.5 times as wide as long); ventral hyposphenia on pereonites 2 and 6. Pleon twice as long as pereonite 5, of 5 free subequal pleonites bearing pleopods; pleonites dorsally convex, 2.5 times as wide as long, laterally expanded by spiniform apophyses. Pleotelson rectangular, short, one-third length of whole pleon, 1.1 times as long as wide, with bunches of lateral setae on similar rounded protuberances to those of pereonites 3 to 6.

Antennule peduncle 4-articled, article 1 3.2 times as long as wide, with inner margin denticulate, setose as figured; 2 0.45 times as long as 1st, with simple inner and longer outer-distal setae; 3 less than half length of article 2, article 4 half as long as article 3, naked. Main flagellum of 8 segments, segments 6 and 8 bearing aesthetascs; accessory flagellum of 5 segments.

Antenna peduncle article 1 simple; article 2 bearing 2 inner and 1 outer marginal seta and elongate squama with 8 marginal setae; peduncle article 3 as long as wide, naked; article 4 slightly longer than article 5, and 4 times as long as article 3. Flagellum of 7 segments.

Mouth parts. Labrum not seen. Left mandible with outer margin naked, bearing narrow crenulated pars incisiva and lacinia mobilis, setiferous lobe with 3 trifurcate setae, pars molaris robust, blunt; mandibular palp of 3 articles, article 1 naked, articles 2 and 3 with 9 ventral setae in distal half, distally with additional 4 longer simple setae. Right mandible as left but without lacinia mobilis. Maxillule inner endite with finely setose outer margin and 5 finely setulate distal setae; outer endite with 11 distal spines and 2 subdistal setae, outer margin finely setose; palp of 2 articles, distally with 5 setae. Maxilla with tuft of setae on outer margin; outer and inner lobes of outer endite with bilaterally setulose setae; outer lobe of inner endite with bilaterally setulose, plumose and trifurcate distal and subdistal spines as figured, outer margin denticulate, inner margin with microtrichia; inner lobe of fixed endite with rostral row of numerous setulose setae guarding 4 longer setae. Labium with fine serrations on outer margin and setulose distal margin, palp with fine lateral setules and 3 simple distal setae. Maxilliped basis with 3 distal setae; palp article 1 with single inner and outer distal setae; palp article 2 longer than wide, with 2 rows of filtering setae on inner margin, the longest as long as article 3, outer margin with 3 spines, distal spine large and robust; palp article 3 longer than wide, with 9 simple setae along inner margin; palp article 4 with 10 distal setae, and single inner and outer subdistal setae. Maxilliped endite with setulose inner caudodistal seta and stout, spatulate, distal spines; 2 coupling hooks. Epignath not seen.

Cheliped slender. Basis 2.9 times as long as wide, dorsally with single fine seta, ventrally with simple proximal seta, midventral spine and 2 distal setae; exopodite present, 3-articled, article 2 with 2 setules, article 3 with 4 plumose setae. Merus elongate, narrowing proximally, with 1 midventral seta and 4 subdistal setae on ventral “shoulder”. Carpus 6.6 times as long as wide, with sparse longer and shorter simple setae along ventral margin, short setae at mid-length and distally on dorsal margin. Chela fingers shorter than palm, ventral margin with 7 setae; 3 outer setae on fixed finger, cutting edge with 8 fine setae but no apophyses; dactylus with 3 subdistal setae but no apophyses on cutting edge, distal claw pointed.

Pereopod 1 with pronounced spine-like apophysis on coxa. Basis stout, 2.6 times as long as wide, with dorsal and ventral marginal setae and ventrodistal spine; exopodite present, 3-articled, article 3 with 4 distal plumose setae. Ischium with 2 simple ventrodistal setae. Merus half as long as basis, with ventrodistal but no dorsodistal stout spine. Carpus 0.75 times as long as merus, with dense tuft of dorsodistal setae surrounding short, stout spine, ventrally with 2 stout spines. Propodus as long as carpus, with 4 ventral and 2 dorsodistal stout spines. Dactylus stout, with 2 middorsal fine setae and ventral denticulations; unguis short.

Pereopod 2 more slender. Basis 4 times as long as wide with sparse setae. Merus 0.9 times as long as carpus, with slender ventrodistal spine. Carpus elongate, with dorsodistal seta as long as article, sparse setae otherwise, and ventrodistal slender spine. Propodus as long as carpus, 2 ventral spines, dorsally with 1 distal and subdistal spines. Dactylus slender with fine dorsal setae, unguis slender, the 2 together just shorter than propodus.

Pereopod 3 similar to pereopod 2, but basis and propodus with penicillate setae, longest seta on ischium longer than merus.

Pereopod 4 basis more robust, twice as long as wide, with dorsoproximal penicillate setae, longest seta on ischium longer than merus, merus with 2 shorter ventrodistal spines and long dorsodistal seta almost as long as carpus, carpus with paired ventral spines, longer distal spines; propodus with dorsoproximal penicillate seta, dorsodistal tuft of 6 short and 2 long finely denticulate setae, distal spines as long as dactylus; dactylus plus unguis two-thirds as long as propodus.

Pereopod 5 similar to pereopod 4; setae on ischium and merus proportionately shorter, dactylus plus unguis proportionately longer, propodus with dorsodistal spines.

Pereopod 6 basis with setae along entire dorsal and ventral margins, paired long dorsal setae on merus and carpus, carpus with slender dorsodistal spine, 18 ventral leaf-like propodal spines extending around distal margin of article.

Pleopods all similar, basis with 2 ventral and 1 dorsal plumose setae, rami elongate, inner ramus setose all round, outer ramus shorter, with naked inner proximal margin.

Uropod biramous, both rami filiform, multi-segmented. Basis with outer row of setae; exopod one-quarter as long as endopod, with 8 segments; endopod elongate, with about 24 segments.

Male unknown.

Etymology. The species in named after the Polish Prime Minister Donald Tusk who was elected as this species was being described..

Remarks. Apseudes tuski sp. nov. is most similar to that group of Apseudes sensu lato with no spiniform apophyses on the cephalon or pereon, and rounded ocular lobes usually with eyes, similar to A. latreilli (Milne-Edwards, 1828) and A. africanus Tattersall, 1925 . The new species appears closest to A. erythraeicus Băcescu, 1984 (q.v.) from the Red Sea, but that species has a dorsodistal spine on the merus, more articles in the antennular main flagellum, proportionately more compact antennular peduncle articles, more setae on the antennal squama and a pointed rostrum. Indeed, in the absence of a dorsodistal spine on the merus, A. tuski approaches the genus Apseudopsis Norman, 1899 sensu Guţu (2006) ; however, the short cephalon, the presence of eyes and the multiarticulated uropod exopod prevent placing the present species in that essentially Mediterranean – North-Atlantic genus, and Guţu (2006) points out that the denticulation of the inner margin of the proximal antennular peduncle article, well-developed in A. tuski , is a feature of Apseudes sensu stricto.

The comparatively blunt rostrum, and the relatively short, blunt marginal spines on pereopod 1, particularly the very short dorsodistal spine on the merus are valuable distinguishing features of A. tuski , while the peculiar outer spination of the proximal maxilliped palp article appears to be unique.