Paratanais malignus Larsen, 2001

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 : 88

Paratanais malignus Larsen, 2001

Figures 58–59

Paratanais malignus Larsen, 2001 , 368–372, figs 11–13, 17.

Material examined. 1 (J56667), Stn BUN2, off Honeysuckle Hill, Bunurong , Victoria , 38º40.32'S 145º37.47'E, 10 to 11 m depth, 1 April 1997, SCUBA, coll. T, D. O’Hara. 2 (J56668), 1 (J56669), Stn WV 11, Beware Reef , near Cape Conran, Victoria , 37º49.21'S 148º47.23'E, 5 to 6 m depth, 15 April 1998, SCUBA, coll. T, D.O’Hara. 3 (J56670), Stn WV 13, Sailor’s Grave, off East Cape Conran, Victoria , 37º48.13'S 148º44.41'E, 4 to 5 m depth, 15 April 1998, SCUBA, coll. T, D. O’Hara. 1 (J56671), Stn WV 5, Cheviot Beach, Point Nepean , Victoria , 38º18'S 144º40'E, 1.9 to 3.5 m depth, 31 March 1998, SCUBA, coll. T, D. O’Hara. 1 (J56694), Stn BSS 213 T, Eastern Bass Strait , 24 km SW of Lakes Entrance, Victoria , 38º03'S 147º50'E, 45 m depth, 01 October 1983, otter trawl, coll. M. Gomon & R. S. Wilson. 1 (J56734), Stn BSS 181 S, Central Bass Strait , 26 km SE of Aireys Inlet, Victoria , 38º39.48'S 144º18.12'E, 79 m depth, very fine sand, 19 November 1981, WHOI epibenthic sledge, coll. R. S. Wilson. 1 (J56738), Stn BSS 188 , Western Bass Strait , 30 km SSW of Warrnambool, Victoria , 38º38.12'S 142º35.00'E, 59 m depth, 20 November 1981, coll. R. S. Wilson. 1 (J56766), Stn PPBES 1218 , Port Phillip Bay, off Brighton , Victoria , 37º54.45'S 144º58.30'E, 4 m depth, coll. Department of Fisheries & Wildlife Marine Pollution Studies. 3 juveniles (J57546), Stn BSS 158 , Central Bass Strait , 66 km S of Rodondo Island, Victoria , 39º48.36'S 146º18.48'E, 82 m depth, sand with silt and mud, 13 November 1981, coll. R. S. Wilson. Numerous other lots in the collections of Museum Victoria .

This species is particularly recognizable owing to its having a leaf-shaped spine at junction of the chela fingers; other characterizing features are the rugose lacinia mobilis of the left mandible, and the dorsal field of marginal setules on article 2 of the antenna peduncle. The additional material found here allows some additions to the type-description of Larsen (2001). The original type-material included only females and mancae; the present material also includes the male, which is described below. Supplementary description of female. Body-length up to 3.7 mm. Distal spine on article three of antennal peduncle often not showing articulation; labrum densely setose ( Fig. 58A). Pars molaris of left mandible with elaborate distal spination ( Fig. 58B). Maxilla ( Fig. 58C) subtriangular, naked. Maxilliped ( Fig. 58D) endites with anteromedial seta (originally described as absent in the more limited type-material), second palp article with long simple seta in addition to serrated spine and finely shorter setulose seta.

Cheliped ( Fig. 58E) carpus with long inner seta; fixed finger of propodus with two ventral setae. Pereopods 1 to 3 ( Figs 58F, G) with seta on coxa.

Description of male. Body ( Fig. 59A) shorter than that of female, 2.6 mm long, 4.8 times as long as wide. Cephalothorax subtriangular, as long as wide, longer than pereonites 1 to 3 together; large eyes present, with large pigmented ocelli. Pereonite 1 shortest, pereonites 2 and 3 progressively longer, pereonite 3 twice as long as pereonite 1, pereonites 4 to 6 equal in length, 2.7 times as long as pereonite 1. Pleon with five free subequal pleonites bearing pleopods.

Antennule ( Fig. 59B) of seven articles, proximal article 1.2 times as long as wide, with inner tuft of penicillate setae; second article 0.7 times as long as wide, about half length of first, with inner seta longer than article width; third article less than half length of second with longer inner and shorter outer distal setae. Flagellum of four segments; first segment very short, with proximal and distal rows of aesthetascs; second segment 2.5 times as long as wide, with distal row of aesthetascs; third segment as long as second, with simple distal seta; fourth segment shorter than third, distally with two penicillate and five simple setae, and single aesthetasc.

Antenna similar to that of female.

Mouthparts ( Fig. 59C) largely reduced. Maxilliped basis with single distal seta, endites naked, palp with simple setae longer than those of female.

Cheliped ( Fig. 59D) compact, more robust than that of female; carpus just longer than wide, with longer ventral and shorter dorsal single setae; propodus with inner comb-row of 14 setae; fixed finger with numerous fine spinules (“teeth”) along cutting edge; dactylus strongly curved, with two setae on inner margin.

Pereopods ( Fig. 59E, F, G) more slender than those of female, pereopods 2 and 3 similar to pereopod 1; posterior pereopods with bases about 2.5 times as long as wide, propodi nearly five times as long as wide and as long as carpus and merus together.

Pleopods ( Fig. 59H) similar to those of female, but setae longer.

Uropod ( Fig. 59I) rami more slender than those of female; exopod almost as long as proximal endopod segment; proximal endopod segment with additional array of penicillate setae in proximal half.

Remarks. The type material of Paratanais malignus was collected in kelp epifauna at 4 to 4.5 m depth in Botany Bay, New South Wales. The present material extends the known distribution to throughout the Bass Strait in depths from 2 to 82 m on sandy to muddy substrata.