Bassoleptochelia verro, 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 : 125-131

Bassoleptochelia verro sp. nov.

Figures 83–86

Material examined. 1 (J58469), holotype, 5 (J55822), paratypes, Stn 81-T-1 177, 38º53.7'S 147º06.5'E, 58 m depth, coarse shell, 18 November 1981 . 1 (J58471), allotype, 1 (J56650), paratype, Stn 81-T-1 199, 40º19.5'S 143º48.8'E, 71 m depth, sandy shell, 22 November 1981 . 4 (J56657), 1 (J56652), paratypes, Stn 81-T-1 203, 39º22.0'S 144º18.3'E, 60 m depth, coarse sand, 23 November 1981 . 13 (J56646), paratypes, Stn 81-T-1 180, 39º12.9'S 146º27.3'E, 65 m depth, medium sand, 18 November 1981 . 1 (J56643), paratype, Stn 81-T-1 187, 38º32.0'S 147º28.6'E, 52 m depth, medium sand, 20 November 1981. All coll. R.S. Wilson , RV Tangaroa . 8, 1 (J56651) , paratypes, Stn 81-Sa-1 116, 40º32.0'S 145º23'E, 43 m depth, muddy shell and grit, 4 November 1980, coll. M.F. Gomon & G.C.B. Poore , FRV Sarda .

Description of female. Body ( Fig. 83A) narrowing anteriorly, holotype 3.8 mm long, 6.4 times as long as wide. Cephalothorax subrectangular, laterally convex, tapering towards anterior, 1.4 times as long as wide, longer than pereonites 1 and 2 together, with slight triangular rostrum, eyelobes extended into spine-like apophysis ( Fig. 84A), eyes present and black, single setae at posterior of eyelobes. Pereonites 1 to 4 with single anterolateral setae, pereonites 5 and 6 with paired lateral setae on each side; pereonites 1 and 2 subequal and shortest, pereonites 3, 4 and 6 subequal, 1.6 times as long as pereonite 1, pereonite 5 longest and twice as long as pereonite 1 (all pereonites respectively 2.0, 2.0, 1.3, 1.5, 1.2 and 1.5 times as wide as long). Pleon with five free subequal pleonites bearing pleopods; each pleonite about 5.3 times as wide as long, with single midlateral seta. Pleotelson pentangular, as long as last two pleonites together, twice as wide as long, with one simple and one penicillate posterolateral seta on each side and two distal setae.

Antennule ( Fig. 84A) of three longer and one minute distal articles, proximal article 2.4 times as long as wide, 1.6 times as long as distal three articles together, with mesial and distal inner groups of penicillate setae, inner and outer simple mesial setae, outer distal seta and one long inner distal seta longer than tip of antennule, outer margin of article finely setulose in proximal half; second article as long as wide, one-quarter as long as first article, inner and outer distal setae three times as long as article; third article 1.3 times as long as second, with two distal setae; fourth article minute, distally with three simple setae, one penicillate seta and one aesthetasc.

Antenna ( Fig. 84B) of six articles, proximal article longer than wide, naked; second article as long as wide, with single inner distal and dorsodistal strong setae; third article half as long as wide, one-third as long as second article, with dorsodistal slender seta; fourth article longest, 3.2 times as long as wide and 4.5 times as long as third, with distal crown of penicillate and simple setae; fifth article 0.6 times as long as fourth; sixth article minute, with three simple distal setae.

Labrum ( Fig. 84C) hood-shaped, finely setose. Left mandible ( Fig. 84E) with simple subrectangular lacinia mobilis, pars incisiva distally bilobed with crenulation on proximal inner margin, pars molaris narrow with slight marginal crenulation distally; right mandible ( Fig. 84D) similar but without lacinia mobilis, pars incisiva distally crenulate. Labium ( Fig. 84G) wide, bilobed, distally finely setose, outer lobe with single outer distal seta, without palp. Maxillule ( Fig. 84F) with eight distal spines, outer distal tuft of setules, rows of setules on inner face; palp with distinct articulation, with two distal setae. Maxilla not recovered. Maxilliped ( Fig. 84H) palp first article elongate, naked; second article with four simple inner setae; third article with five inner marginal finely-denticulate setae; fourth article with six longer and one shorter distal finely denticulate setae and one outer subdistal seta; basis with three long setae extending to third palp article; endites distally with fine outer setules and three elongate spatulate spines and long inner simple seta. Epignath not recovered.

Cheliped ( Fig. 85A) with elongate slender basis 3.5 times as long as wide; merus subtriangular with brush of nine ventral setae and one outer dorsoproximal seta; carpus twice as long as wide, with three midventral setae on slightly flattened edge and four shorter dorsal marginal setae, dorsoproximal margin of carpus slightly crenulate; propodus relatively slender, 1.3 times as long as wide, with inner distal comb of three setae and longer seta at base of dactylus; fixed finger with two ventral and three inner setae, cutting edge crenulate; dactylus with proximal seta, cutting edge simple.

Pereopod 1 ( Fig. 85B) slender, longer than other pereopods, coxa with seta; basis 3.5 times as long as wide, with single dorsoproximal simple seta; ischium compact with one ventral seta; merus slender, six times as long as wide and as long as carpus, with one dorsodistal seta; carpus widening distally, with single ventrodistal, inner and outer distal and dorsodistal setae, longest of which is less than half length of propodus; propodus 1.5 times as long as carpus, with three setae on subdistal dorsal mound and one subdistal ventral seta; dactylus slender, extending into longer slender unguis 1.4 times as long as dactylus, the two together 0.85 times as long as propodus. Pereopod 2 ( Fig. 85C) more compact than pereopod 1; basis 2.2 times as long as wide, with dorsoproximal penicillate seta; ischium with two ventral setae; merus as long as carpus and as long as wide, with small ventrodistal spine, ventrodistal seta and ventral rows of microtrichia; carpus with single dorsodistal and two ventrodistal setae and ventral rows of microtrichia; propodus 1.6 times as long as carpus, with two distal setae, dorsodistal sharp apophysis and ventral rows of microtrichia; dactylus and subequal unguis only slightly curved, together 0.9 times as long as propodus, proximal seta on dactylus. Pereopod 3 ( Fig. 85D) similar to pereopod 2, but basis with fields of microtrichia, merus without ventrodistal spine.

Pereopod 4 ( Fig. 85E) basis stout, twice as long as wide with midventral penicillate seta; ischium with two ventrodistal setae; merus with paired ventrodistal slender spines and ventral rows of microtrichia; carpus just longer than merus, with dorsodistal seta and ventral rows of microtrichia; propodus as long as carpus, with two ventrodistal spines, three dorsodistal setae longer than dactylus, and ventral rows of microtrichia; dactylus and distinct, short unguis curved, 0.9 times as long as propodus, with lateral rows of microtrichia. Pereopod 5 as pereopod 4. Pereopod 6 ( Fig. 85F) as pereopod 4, but carpus with dense field of microtrichia, propodus with four distal setae.

Pleopods ( Fig. 85G) all alike, typical for the genus, basis naked, endopod with single inner plumose seta and proximal outer seta separated from remainder.

Uropod ( Fig. 85H) biramous, basis with outer distal seta; exopod of one segment, as long as proximal endopod segment, outer distal seta longer than inner distal seta; endopod of four segments, distal segment slender.

Subadults. Neuter, juvenile and manca essentially smaller versions of adult female ( Figs 83B, C, D).

Description of male. Smaller than female (allotype length 1.5 mm), body ( Fig. 83E) more compact, cephalon as long as pereonites 1 to 3 together, with large eyelobes bearing large black eyes; pereonite 1 shortest, pereonites 2 and 3 respectively 1.3 and 1.5 times as long as pereonite 1, pereonite 4 longest, 2.7 times as long as pereonite 1, pereonites 5 and 6 progressively shorter, respectively 2.2 and 1.8 times as long as pereonite 1. Five free pleonites, subequal in length, each as long as pereonite 2, pleotelson 1.4 times as long as pleonite 5.

Antennule ( Fig. 86A) peduncle compact, first peduncle article twice as long as wide, with ventrodistal tuft of penicillate and simple setae; second article 0.4 times as long as first and as long as wide, with ventrodistal tuft of penicillate and simple setae; third article 0.25 times as long as first and slightly shorter than wide with single ventral and long dorsal distal simple setae; flagellum of 6 segments, segment 1 with proximal and distal rows of aesthetascs, segments 2 to 5 bearing distal row of 3 to 5 aesthetascs, segment 6 with four distal setae.

Antenna ( Fig. 86B) of six articles, proximal article longer than wide, naked; second article as long as first, with three distal setae; third article shorter than second, with two distal setae; fourth article longest, 1.6 times as long as second and 4 times as long as wide, with mesial simple and penicillate setae and distally one penicillate and three long simple setae; fifth article 0.8 times as long as fourth; sixth article minute, with four simple distal setae.

Mouthparts ( Fig. 86C) atrophied, naked maxilliped and maxillule palp with two distal setae distinguishable.

Cheliped ( Fig. 86D) proportionately larger than that of female; basis three times as long as wide; merus short, with brush of seven ventral setae; carpus 1.8 times as long as wide, with twp midventral setae. Propodus almost square, 1.3 times as long as wide, fixed finger short with slender distal claw, with two ventral setae and three setae adjacent to naked, simple cutting edge; large, triangular tooth-like apophyses on distal face of propodus, and inner vertical comb-row of 8 shorter and one longer setae; dactylus slender, curved, nearly three times as long as propodal fixed finger, with proximal seta and three spinules on cutting edge, articulation of unguis obscure.

Pereopod 1 ( Fig. 86E) similar to that of female but propodus proportionately longer (1.8 times as long as carpus) and more elongate; pereopods 2 ( Fig. 86F) and 3 similar to but shorter than pereopod 1, carpus with distal crown of setae. Pereopods 4 to 6 (e.g. Fig. 86G, H) ambulatory, merus, carpus and propodus slender, all distal spines more elongate than those of female but distal setae proportionately shorter, microtrichia restricted to carpus and propodus without dense brush on pereopod 6, dactylus long and slender, naked, 0.7 times as long as propodus, unguis just less than half as long as dactylus.

Pleopods with longer setae than on those of female. Uropod ( Fig. 86I) similar to that of female.

Etymology. From the Latin – verro – a brush, in reference to the tuft of setae on the cheliped merus and the dense fields of microtrichia on the posterior pereopods, especially the carpus of pereopod 6, analogous to the “prickly tubercles” found in some typhlotanaids (noun in apposition).

Remarks. The numerous distinctions of this species from other leptocheliids are described under the remarks for the genus, and again it contributes to the great diversity of the Leptocheliidae in Australian waters. Bassoleptochelia verro sp. nov. was found on coarser sandy substrata at depths from 43 to 71 m right across the Bass Strait.