Peraeospinosus tanytrix, 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 : 179-183

Peraeospinosus tanytrix sp. nov.

Figures 120–122

Material examined. 1 (J58534), holotype, and 107, 36 neuters (J58535), paratypes, Eastern Bass Strait, 63 km E of North Point, Flinders Island, Stn BSS 167 , 39º44.8'S 148º40.6'E, 124 m depth, fine sand and mud, 14 November 1981 ; coll. R.S. Wilson ; 5 and 1 neuter (J58896) , paratypes, Stn BSS 167 G, 1 (J58898) , paratype, Stn BSS 167 S, same data as holotype; 1 (J58895), 7 in tubes with numerous mancae (J58897) , paratypes, Eastern Bass Strait, 60 km E of North Point, Flinders Island, Stn BSS 32 , 39º41.7'S 148º39.5'E, 115 m depth, muddy sand, 27 March 1979; coll. G.C.B. Poore ; 1 (J58899), paratype, Eastern Bass Strait, 100 km NE of North Point, Flinders Island, Stn BSS 170 , 38º52.6'S 148º25.2'E, 130m depth, fine sand, 15 November 1981 ; coll. R.S. Wilson ; 1 (J58900) , paratype, Eastern Bass Strait, 28 km SSW of Marlo, Stn BSS 207 , 37º59'S 148º27'E, 51 m depth, muddy sand and fine shell, 30 July 1983; coll. M.F. Gomon ; 4 in tubes with mancae (J57817), paratypes, 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 ; 7 with tubes (J37858), paratypes, off Nowra, New South Wales, Stn SLOPE 2 , 34º57.9'S 151º08.0'E, 503 m depth, 14 July 1986; coll. G.C.B. Poore ; 2 (J37883), paratypes, off Nowra, New South Wales, Stn SLOPE 7 , 34º52.28'S 151º15.02'E to 34º51.13'S 151º15.13'E, 1096 m depth, 15 July 1986; coll. G.C.B. Poore & C.-C. Lu.

Description of female. Body ( Fig. 120A, B) slender, holotype 4.7 mm long, seven times as long as wide. Cephalothorax rounded but tapering towards anterior with triangular rostrum, as long as wide, naked, eyes absent. Pereonite 1 wider anteriorly, just over half as long as cephalothorax; pereonites 2 and 3 narrowed at mid-length, subequal in length, 1.6 times as long as pereonite 1; pereonites 4 and 5 subrectangular, subequal in length, 1.1 times as long as pereonite 1; pereonite 6 with midlateral creases, shortest, 0.8 times as long as pereonite 1 (all pereonites respectively 1.7, 0.9, 0.8, 1.2, 1.2 and 1.5 times as wide as long). Pleon with five free subequal pleonites bearing pleopods; each pleonite six times as wide as long. Pleotelson semicircular, one-third length of pleon and twice as wide as long, with two small distal setae ( Fig. 122H).

Antennule ( Fig. 121A) of three articles, proximal article clavate, twice as wide proximally as distally, 3.3 times as long as wide, 1.6 times as long as distal two articles together, with row of three fine inner-dorsal setae, outer margin with tufts of three, four and three penicillate setae proximally, at mid-length and distally, last two tufts with accompanying simple seta; second article 1.3 times as long as wide, one-third as long as third article, with two unequal dorsodistal simple setae; third article tapering, almost half as long as first article, with five simple distal setae.

Antenna ( Fig. 121B) of six articles, proximal article compact, as long as second article, with ventral microtrichia; second article swollen, as long as wide, with ventral microtrichia; third article shorter than wide, 0.7 times as long as second article, with fine dorsodistal seta; fourth article longest, 8.4 times as long as wide, four times as long as second article, curved, with two simple and two penicillate distal setae; fifth article half as long as fourth with one distal seta; sixth article minute with five distal setae.

Labrum ( Fig. 121C) rounded, hood-shaped, distally setose. Left mandible ( Fig. 121D) with subtriangular, crenulate pars incisiva and wide, crenulate lacinia mobilis, right mandible ( Fig. 121E) with rounded, smooth cutting edge on pars incisiva, without lacinia mobilis; pars molaris of both mandibles with fine denticulations around distal margin. Labium ( Fig. 121H) simple, finely setose on distal margin and with rows of microtrichia on outer margins. Maxillule ( Fig. 121F) with nine distal spines and sparse microtrichia, palp not recovered. Maxilla ( Fig. 121G) ovoid, naked. Maxilliped ( Fig. 121I) palp first article naked, remaining articles with microtrichia; second article with one outer simple seta and three inner setae finely denticulate in distal half; third article with four inner setae in distal half of article, two of these finely denticulate in distal half; fourth with five inner to distal setae finely denticulate in distal half; basis with single seta about half as long as endites; endites distally with two setae. Epignath not recovered.

Cheliped ( Fig. 122A) basis not quite reaching anterior margin of pereonite 1 ventrally, 1.4 times as long as wide, with single dorsodistal seta; merus subtriangular with single ventral seta; carpus 1.5 times as long as wide, with two midventral setae, one fine dorsodistal seta, and row of five setae along dorsal margin, ventral margin distally invaginated to accommodate propodus on reflexion; propodus about as long as wide, fixed finger as long as palm, with two ventral setae, three setae on cutting edge; dactylus naked.

Pereopod 1 ( Fig. 122B) coxa without apophysis, naked; basis arcuate, slender, 5.7 times as long as wide, with seven fine setae along dorsal margin and three more along ventral margin; ischium compact, with fine ventral seta; merus elongate, 0.6 times as long as basis and 4.7 times as long as wide, with mid-dorsal fine seta and three simple distal setae; carpus 0.6 times as long as merus, 2.5 times as long as wide, with distal crown of five simple setae; propodus 1.5 times as long as carpus, six times as long as wide, with two dorsal subdistal setae; short, stout dactylus with proximal seta longer than dactylus, slender unguis 1.4 times as long as dactylus, both together 0.4 times as long as propodus. Pereopod 2 ( Fig. 122C), coxa similar to that of pereopod 1, basis 4.9 times as long as wide, with one penicillate and four fine simple setae along dorsal margin and three simple setae along ventral margin; ischium with ventral seta; merus 0.25 times as long as basis, with single dorsodistal seta, short ventrodistal spine, and dense field of microtrichia across ventral and ventrolateral surfaces in distal two-thirds; carpus 0.9 times as long as merus, with dorsal, mesial and ventral distal setae, short ventrodistal spine, and dense field of microtrichia across ventral and ventrolateral surfaces; propodus 2.6 times as long as carpus, with ventral subdistal seta, one shorter dorsodistal seta, one very long dorsodistal seta 1.3 times as long as propodus; short, stout dactylus with proximal seta exceeding tip of subequal slender unguis, both together one-third as long as propodus. Pereopod 3 ( Fig. 122D) similar to pereopod 2, basis without penicillate seta; merus with additional ventrodistal seta; dactylus and unguis together 0.2 times as long as propodus, long distal seta 1.6 times as long as propodus.

Pereopod 4 ( Fig. 122E) basis stout, 1.5 times as long as wide, with two simple mid-dorsal seta and two dorsoproximal and two ventrodistal penicillate setae; ischium with two ventrodistal setae; merus 1.2 times as long as carpus, with field of microtrichia across ventral and ventrolateral surfaces in distal half, and two small ventrodistal spines; carpus with two hooked distal spines, fine dorsodistal seta, and prickly tubercle surrounded by minute spines and microtrichia in ventrodistal half; propodus 1.3 times as long as carpus, with mid-dorsal penicillate seta, strong dorsodistal seta, and two short ventrodistal spines; dactylus slender, nearly three times as long as denticulate unguis, both together half as long as propodus. Pereopod 5 (not figured) as pereopod 4. Pereopod 6 ( Fig. 122F) similar to pereopod 4, but basis without penicillate setae, propodus with three dorsodistal setae.

Pleopods ( Fig. 122G) all alike, with naked basis, exopod shorter than endopod; endopod and exopod without setae on inner margin, outer margins with respectively 19 and 31 plumose setae, proximal seta on both rami slightly separated from others.

Uropod ( Fig. 122H) biramous, basis naked; exopod and endopod of one segment, subequal in length; exopod with one fine proximal, one stout distal setae; endopod with four simple and three penicillate distal setae.

Male. Unknown.

Etymology. From the Greek tany – long, and thrix – a hair, with reference to the exceedingly long distal seta on the propodi of pereopods 2 and 3.

Remarks. The genus Peraeospinosus was reviewed most recently by Błażewicz-Paszkowycz (2005), who presented an identification key to the ten species then described; in that key, P. tanytrix sp. nov. identifies as P. emergensis Błażewicz-Paszkowycz, 2005 , sharing the rounded cephalothorax not longer than wide and the elongate pereonites 1 to 3, but does not share with that species the elongate merus, carpus and propodus of pereopod 2, nor the elongate dorso-distal “rodseta” on the carpus of pereopod 1. The only other species described since that key is P. acruxi Błażewicz-Paszkowycz, 2007 , which shares with P. emergensis the pereopod 1 rod seta and elongate anterior pereonites, but has a cephalothorax longer than wide. Most distinctively, none of the eleven previously described species have such an extraordinarily long distal seta on the propodi of pereopods 2 and 3 as found in P. tanytrix , although this condition is approached in some species of Torquella Błażewicz-Paszkowycz, 2007 .

Peraeospinosus tanytrix was collected from Eastern Bass Strait at depths between 51 and 1096 m. The tubes, apparently used for brooding, were of agglomerated sediment particles and fibrous material.