Inconnivus billibunteri, 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 : 157-162

Inconnivus billibunteri sp. nov.

Figures 105–107

Material examined. 1 (J37873), holotype, off Nowra, New South Wales, Stn SLOPE 1 , 34º59.52'S 151º05.93'E, 204 m depth, 14 July 1986; coll. G.C.B. Poore ; 1 (J58564), paratype, Central Bass Strait, 25 km SW of Cape Frankland, Flinders Island , Stn BSS 162 , 40º09.4'S 147º32.6'E, 51 m depth, shelly sand, 14 November 1981 ; coll. R.S. Wilson; 1 (J58903) , 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 .

Description of female. Body ( Fig. 105) compact, holotype 2.9 mm long, 4.8 times as long as wide. Cephalothorax narrowing towards anterior, as long as wide, about as long as pereonites 1 to 4 together, naked; eyelobes present, eyes absent. All pereonites laterally convex; pereonites 1 to 3 subequal in length, narrow, less than one-quarter as long as cephalothorax; pereonite 4 longest, 1.5 times as long as pereonite 3; pereonites 5 and 6 subequal, 0.9 times as long as pereonite 4 (all pereonites respectively 4, 4.4, 3.8, 2.3, 2.7 and 2.9 times as wide as long). Five free subequal pleonites bearing pleopods; each pleonite 6.4 times as wide as long. Pleotelson semicircular, as long as maximum width, longer than last three pleonites together, naked.

Antennule ( Fig. 106A) of four articles, proximal article 2.4 times as long as wide, 1.3 times as long as distal three articles together, with mid-dorsal row of two simple and about eight penicillate setae; second article slightly longer than wide, one-third as long as first article, with distal tuft of one simple and four penicillate setae; third article compact, one-third as long as second article, with two simple distal setae; fourth article 2.5 times as long as third with six simple distal setae and one aesthetasc.

Antenna ( Fig. 106B) proximal article compact, fused to cephalothorax; second article as long as wide, with distal seta and dorsodistal spinule; third article as long as wide, with dorsodistal seta; fourth article longest, 3.9 times as long as wide, with suggestion of secondary articulation just proximal of mid-length, and with one penicillate seta just proximal of mid-length and group of three simple and three penicillate distal setae; fifth article 0.3 times as long as fourth with one simple distal seta; sixth article minute with four distal setae.

Labrum ( Fig. 106C) rounded, distally setose. Left mandible ( Fig. 106D) with narrow, irregularly-crenulate pars incisiva, lacinia mobilis triangular with fine outer denticulations, right mandible ( Fig. 106E) as left but without lacinia mobilis; pars molaris of both mandibles robust with slender ventrodistal spines. Labium ( Fig. 106H) simple, elongate, with outer-distal spinule. Maxillule ( Fig. 106F) with nine distal spines, six of these slender, scythe-like with fine denticulations; palp not recovered. Maxilliped palp ( Fig. 106G) with groups of microtrichia; first article naked; second article with outer distal seta and three longer inner-distal setae; third article with four inner setae, longest seta much longer than article; fourth article damaged in preparation; basis with single, long seta not reaching distal margin of endites; endites distally with two oval tubercles. Epignath not recovered.

Cheliped ( Fig. 107A) sclerite with triangular attachment to basis; basis just longer than wide and bearing microtrichia; merus subtriangular with single ventral seta; carpus rounded, compact, 1.1 times as long as wide, with two midventral setae, one dorsoproximal and one dorsodistal setae; propodus as long as carpus, with comb-row of four setae, fixed finger with two ventral and one inner setae, three setae on cutting edge, cutting edge crenulate; dactylus with robust row of rounded crenulations along outer dorsal margin, cutting edge with three coarser crenulations.

Pereopod 1 ( Fig. 107B) coxa naked; basis slender, 4.5 times as long as wide, with mid-ventral microtrichia and ventrodistal seta; ischium compact with long ventral seta 0.85 times as long as merus; merus, carpus and propodus subequal in length; merus with midventral microtrichia and ventrodistal spine; carpus with microtrichia, ventrodistal spine, two inner-distal setae and long dorsodistal spine, 0.75 times as long as propodus and with inner denticulation; propodus with ventral microtrichia, subdistal dorsal seta and ventrodistal spine longer than dactylus; dactylus and claw subequal in length, both together 1.15 times as long as propodus. Pereopod 2 ( Fig. 107C) similar to pereopod 1, basis four times as long as wide, without ventrodistal seta; carpus with two ventrodistal spines, dorsodistal spine half as long as propodus; propodus 1.3 times as long as carpus, without dorsal seta; dactylus with proximal seta. Pereopod 3 ( Fig. 107D) similar to pereopod 2 but carpus and propodus subequal in length and 1.4 times as long as merus.

Pereopod 4 ( Fig. 107E) basis stout, 2.5 times as long as wide, with two penicillate setae; ischium with ventrodistal seta as long as merus; merus shorter than carpus, with two finely-denticulate ventrodistal spines; carpus with three finely-denticulate ventrodistal spines and slender dorsodistal blunt spine; propodus 1.2 times as long as carpus, with dorsal penicillate seta, ventral rows of microtrichia, and three distal spines almost as long as dactylus; dactylus and claw subequal in length, curved, both together 1.3 times as long as propodus. Pereopod 5 ( Fig. 107F) as pereopod 4, but seta on ischium longer than merus, merus and carpus subequal in length, distal setae on propodus longer than dactylus. Pereopod 6 ( Fig. 107G) as pereopod 4, but basis more slender (3.25 times as long as wide), propodus with four distal finely-denticulate spines and one simple seta.

Pleopods ( Fig. 107H) all alike, with naked basis, endopod shorter than exopod, both without setae on inner margin, outer margins with respectively 7 and 14 plumose setae.

Uropod ( Fig. 107I) short; basis naked and with minute rounded exopodal process bearing two long and one short distal setae; endopod of one segment just longer than basis, with two penicillate setae at mid-length and array of five simple distal setae.

Male. Unknown.

Etymology. named after William George (“Billy”) Bunter, a proportionately-fat schoolboy character in books written by Charles Hamilton using the pen-name Frank Richards.

Remarks. The characterizing features of this species, which distinguish it from the related genus Tanaella , particularly the presence of eyelobes, are described above under the generic remarks. Further, it is much less slender than species of Tanaella . In comparison with those species, Inconnivus billibunteri sp. nov. would key out to T. mclellandi Larsen and Heard, 2004b , in the key to the genus given by Guerrero-Kommritz & Blazewicz-Paszkowycz (2004) but the antennule is distinct, the uropods too short, the chela smaller, the propodi of pereopods 1 and 2 proportionately shorter, and pleopods are present.

Since that publication, two further species of Tanaella have been described. T. kommritzia Larsen & Shimomura, 2007 (a) has much longer (and incurved) uropods, inter alia, and is distinctly more slender. The only species of Tanaella recorded from Australia, T. dongo Bamber, 2005 , is the slenderest of the genus, and has a 2-segmented uropod. Neither, of course, has eyelobes.

Inconnivus billibunteri was collected sporadically at depths from 51 to 204 m on shelly to fine sand substrata.

Family Mirandotanaidae Błażewicz-Paszkowycz & Bamber, 2009