Araphuroides stabastris, 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 : 144-149

Araphuroides stabastris sp. nov.

Figures 96–99

Material examined. 1 (J58536), holotype, Central Bass Strait , 33 km S of Deal Island, Stn BSS 161 , 39º48.3'S 147º19.2'E, 60 m depth,muddy sand, 14 November 1981 ; coll. R.S. Wilson; 1 (J58544) , allotype, Central Bass Strait , 35 km NNE of Cape Wickham, King Island , Tasmania, Stn BSS 204 DRC, 39º16.0'S 144º05.4'E, 82 m depth, sandy shell, 23 November 1981 ; coll. R.S. Wilson; 2 (J58537) , paratypes, Central Bass Strait , 33 km S of Deal Island, Stn BSS 161 , 39º48.3'S 147º19.2'E, 60 m depth, muddy sand, 14 November 1981 ; coll. R.S. Wilson; 5 (J58538) , paratypes, Central Bass Strait , 44 km NE of Cape Wickham, King Island, Stn BSS 203 , 39º22.0'S 144º18.3'E, 60 m depth, coarse sand, 23 November 1981 ; coll. R.S. Wilson; 1 (J58541) , paratype, Central Bass Strait , 38 km SW of Cape Paterson, Stn BSS 155 , 38º55.5'S 145º17.00'E, 70 m depth, fine sand, 12 November 1981 ; coll. R.S. Wilson; 1 (J58540) , paratype, Eastern Bass Strait , 24 km NNE of Eddystone Point, Stn BSS 163 G, 40º43.9'S 148º32.5'E, 56 m depth, muddy sand, 14 November 1981 ; coll. R.S. Wilson; 2 (J58543) , paratypes, Central Bass Strait , 65 km ENE of Cape Rochon, Three Hummock Island, Stn BSS 157 , 40º10.9'S 145º44.3'E, 75 m depth, shelly sand, 13 November 1981 ; coll. R.S. Wilson; 1 (J58546) , paratype, Eastern Bass Strait , 100 km NE of North Point, Flinders Island, Stn BSS 170 , 38º52.6'S 148º25.2'E, 130 m depth, fine sand, 15 November 1981 ; coll. R.S. Wilson; 1 (J58548) , paratype, Eastern Bass Strait , 28 km SSW of Marlo, Stn BSS 207 , 37º59.0'S 148º27.0'E, 51 m depth, muddy sand and fine shell, 30 July 1983; coll. M.F. Gomon ; 1 (J58539), paratype, Central Bass Strait , 25 km SW of Cape Frankland, Flinders Island, Stn BSS 162 , 40º09.4'S 147º32.7'E, 51 m depth, shelly sand, 14 November 1981 ; coll. R.S. Wilson; 2 (J58542) , paratypes, Western Bass Strait , 40 km SSW of Warrnambool, Victoria, Stn BSS 189 , 38º42.8'S 142º35.6'E, 69 m depth, coarse sand, 20 November 1981 ; coll. R.S. Wilson; 2 (J58561) , paratypes, Central Bass Strait , 99 km WSW of Cape Liptrap, Stn BSS 131 T, 39º45.55'S 145º33.82'E to 39º48.03'S 145º32.58'E, 78.7 m depth, very fine sand, 03 February 1981; coll. M.F. Gomon, G.C.B. Poore & C.-C. Lu.

Description of female. Body ( Fig. 96A, B) slender, holotype 2.35 mm long, 7 times as long as wide. Cephalothorax subrectangular, tapering anteriorly with slight triangular rostrum, 1.3 times as long as wide, longer than pereonites 1 and 2 together, naked, eyes absent. Pereonite 1 shortest, 0.4 times as long as cephalothorax; pereonites 2 to 6 subequal, half as long as cephalothorax, with rounded lateral margins and wider than long (all pereonites respectively 2.0, 1.6, 1.4, 1.3, 1.3 and 1.4 times as wide as long). Pleon of five free subequal pleonites without pleopods plus pleotelson; each pleonite 3.2 times as wide as long. Pleotelson pentangular, as long as last pereonite, with paired posterior setae on each side.

Antennule ( Fig. 97A) of four articles, proximal article 1.6 times as long as wide, 1.3 times as long as distal three articles together, with single outer distal simple seta surrounded by four penicillate setae; second article just longer than wide, 0.3 times as long as first article, with outer distal tuft of one simple and two penicillate setae; third article two-thirds as long as second, distally with outer simple seta and inner pair of one simple and one penicillate setae; fourth article tapering, just longer than second article, with six distal setae and one aesthetasc.

Antenna ( Fig. 97B) of six articles, proximal article compact, fused to cephalothorax; second and third articles as long as wide, each with dorsodistal seta; fourth article longest, as long as three proximal articles together and 4.3 times as long as wide, with two simple and two penicillate distal setae; fifth article as long as third, with one distal seta; sixth article minute with four distal setae.

Labrum ( Fig. 97C) rounded, hood-shaped, setose. Left mandible ( Fig. 97D) with irregularly denticulate pars incisiva and triangular, crenulate lacinia mobilis, right mandible ( Fig. 97E) with bilobed pars incisiva and without lacinia mobilis; pars molaris apically tuberculate. Labium ( Fig. 97G) simple, finely setose at outer distal corners, without palp. Maxillule ( Fig. 97F) with eight distal spines, each distally finely-denticulate, palp ( Fig. 97 F') with two distal setae. Maxilla ( Fig. 97H) simple, naked. Maxilliped palp ( Fig. 97I) first article with single outer distal seta; second article with three inner setae, two of these distally finely serrated; third article with two longer and two shorter inner setae; fourth article with five distal setae, each distally finely serrated, and one outer subdistal seta; basis with single, long seta almost reaching distal margin of endites; endites distally with two setae and rounded tubercle.

Cheliped ( Fig. 98A) with rounded, naked basis about twice as long as wide; merus subtriangular with single ventral seta and covering more than half of ventral margin of carpus; carpus 1.5 times as long as wide, with two midventral setae, one dorsodistal seta; propodus as long as wide, comb-row of three setae, fixed finger with two ventral and three setae below cutting edge; dactylus naked.

Pereopod 1 ( Fig. 98B) coxa without apophysis, with seta; basis slender, five times as long as wide, naked; ischium compact with one ventral seta; merus one-quarter as long as basis, with slender ventrodistal spine; carpus 1.75 times as long as merus, distally with inner seta and single distally-denticulate spine dorsally and two ventrally; propodus 1.25 times as long as carpus, with ventrodistal seta and distal tuft of setules; dactylus 0.42 times as long as unguis, both together 1.3 times as long as propodus. Pereopod 2 ( Fig. 98C) similar to pereopod 1 although articles proportionately shorter, basis four times as long as wide with two mid-dorsal penicillate setae. Pereopod 3 ( Fig. 98D) similar to pereopod 2.

Pereopod 4 ( Fig. 98E) basis stouter, 3.6 times as long as wide, with two mid-ventral penicillate setae; ischium with two ventral setae; merus two-thirds as long as carpus and with two ventrodistal spines; carpus with three distal spines; propodus 1.14 times as long as carpus, with dorsal penicillate seta and three distal spines, each with fine serrations; dactylus longer than distinct unguis, both together just longer than propodus. Pereopod 5 ( Fig. 98F) as pereopod 4, but all spines showing fine serrations, microtrichia present on propodus and dactylus. Pereopod 6 ( Fig. 98G) as pereopod 5, but propodus with four distal spines, and basis without penicillate setae.

Pleopods absent.

Uropod ( Fig. 98H) basis naked, exopod process 0.7 times as long as endopod, with one mesial and one distal setae; endopod of one segment, with subdistal tuft of two penicillate setae and distal group of five simple and one penicillate setae.

Distinctions of male ( Fig. 99). Generally similar to female, allotype body length 2.9 mm; pereonite 2 only half as long as wide. Antennule with incipient articulation of distal article. Five pairs of pleopods present, rami subequal in length, exopod with nine distal setae, endopod with eight distal and one inner subdistal setae.

Etymology. Stabastris is an anagram of Bass Strait.

Remarks. The genus Araphuroides is distinguished from Araphura and Tanaella in having pereonites laterally rounded and wider than long (unlike Araphura ), with a distinct uropodal exopod-process (unlike Tanaella ), but see discussion below. Larsen (2005) re-diagnosed the genus and gave a key to the four species then known, in which A. stabastris sp. nov. is not resolved. Since that paper, A. io (Bamber,2005) was transferred to this genus from Araphura by Larsen et al. (2009), and the present species is indeed closest to A. io, a species recorded from south-western Western Australia at depths from 23 to 40 m.

Araphuroides stabastris is distinguished from A. io in having a shorter cephalothorax; a cheliped with two ventral carpal setae, and only three setae in the chela comb-row; pereopod 1 with a more elongate basis (five times as long as wide, only three times in A. io), a carpus approaching twice as long as the merus (subequal in A. io), and a proportionately longer unguis (2.4 times as long as dactylus, only 1.3 times in A. io); all pereopods with a proportionately longer dactylus plus unguis, proportionately longer carpus, and longer distal spines on the merus and carpus. In addition, A. io has pleopods in the female. Both species are without a line of pseudo-articulation on the fourth antennal article found in all other species apart from A. bombus Larsen, 2005 .

Araphuroides stabastris was found at 31 to 71 m depth on muddy to shelly sands throughout the Bass Strait.