Pakistanapseudes bassi, Błażewicz-Paszkowycz, Magdalena & Bamber, Roger N, 2007

Błażewicz-Paszkowycz, Magdalena & Bamber, Roger N, 2007, Parapseudid tanaidaceans (Crustacea: Tanaidacea: Apseudomorpha) from Eastern Australia, Zootaxa 1401, pp. 1-32 : 14-19

Pakistanapseudes bassi sp. nov. ( Figs 7–9 )

Diagnosis. Rostrum rounded; eyes present, pigmented; pereonites 5 and 6 longer than wide. Antennal squama bearing ten marginal setae. Marginal spines on pereopod 1 propodus distally pointed; simple (not bifurcate) claw on pereopods 2 and 3. Pleopod basis with naked ventral margin.

Material examined: Holotype: female, NMV J53136 , BSS 165, Australia, Tasmania, Eastern Bass Strait, 42 km SW of Babel Island 40°14.24’S, 148°40.0’E, depth 60 m, fine sand. Paratypes: 3 males, NMV J55292 , 1 female dissected on slides, NMV J55293 , same locality as holotype. Other Material: 1 specimen, BSS 36, Eastern Bass Strait, 82 km ENE of North Point, Flinders Island, 39°27.7’S, 148°41.4’E, depth 293 m, coarse sand, 28 Mar 1979; 1 specimen, BSS 183, Western Bass Strait, 35 km SSW of Cape Otway, 39’07.0’S, 143°14.6’E, depth 84 m, coarse sand, 20 Nov 1981, depth 84 m; 1 specimen, 76, Western Bass Strait, 42 km NW of Cape Farewell, King Island, (39°19’S, 143°38’E), depth 95 m, coarse sand, carbonate, 10 Oct 1980; 1 specimen, BSS 50, Western Bass Strait, 15 km S of Cape Otway, 39°00’S, 143°32’E, depth 79 m, medium sand, 8 Oct 1980; 1 specimen, BSS 169, 69 Eastern Bass Strait, 85 km NE of North Point, Flinders Island, 39°02.4’S, 148°30.6’E, depth 120 m, muddy sand, 15 Nov 1981; 1 specimen, BSS 202, 202 60 km SW of Cape Schanck, 39°00.2’S, 2’S, 144°33.9’E, depth 74 m, sandy shell, 23 Nov 1981; 34 specimens, BSS 167, Eastern Bass Strait, 63 km E of North Point, Flinders Island, 39°44.8’S, 148°40.6’E, depth 124 m, muddy sand, 14 Nov 1981.

Etymology. The name derives from Bass Strait, the type locality.

Descriptio n of female. Body ( Fig. 7 ), dorsoventrally flattened, attenuate, holotype 4.5 mm long (tip of rostrum to posterior of pleotelson), 7.3 times as long as wide, tapering towards posterior. Cephalothorax subrectangular, as long as wide, with widely rounded rostrum; eyelobes distinct, eyes present. Six free pereonites; pereonites 1 and 2 subequal, shortest, about one­third as long as cephalothorax, pereonite 3 1.7 times as long as pereonite 2, pereonites 4 and 6 subequal, twice as long as pereonite 2; pereonite 5 longest, 2.4 times as long as pereonite 2 (all pereonites respectively 2.8, 2.3, 1.3, 1.2, 0.9 and 0.9 times as wide as long); pereonites with one (occasionally two) setae in distal and proximal corners. Pleon three times as long as pereonite 6, of five free subequal pleonites bearing pleopods; pleonites 1.6 times as wide as long, each with two setae. Pleotelson 1.5 times as long as pleonite 6, 1.3 times as long as wide, with one seta on each side.

Antennule ( Fig. 8 A). Proximal peduncle article 2.6 times as long as wide, with median and subdistal outer tufts of setae, two inner proximal plumose sensory setae and three distal inner setae longer than article width, reaching distal margin of article 2; second peduncle article 1.5 times as long as wide, half length of first with inner median and subdistal tufts of setae and outer distal group of simple and plumose­sensory setae. Article 3 about half length of second, as long as wide, with long simple inner and outer distal setae. Peduncle article 4 shorter than article 3, wider than long. Main flagellum of seventeen segments, single aesthetasc present on segment fifteen; accessory flagellum of eleven segments.

Antenna ( Fig. 8 B) with inner, rounded, naked apophysis on proximal peduncle article. Article 2 longest, with single simple seta adjacent to elongate squama bearing ten marginal setae. Peduncle article 3 shorter than wide with inner plumose sensory seta. Article 4 as long as third, with two inner plumose sensory setae. Article 5 very short. Flagellum of eleven segments.

Mouth parts. Left mandible ( Fig. 8 C) with strong, multidentate pars incisiva and lacinia mobilis; setiferous lobe with four compound and one simple setae, pars molaris stout, blunt with distal rugosity; palp ( Fig. 8 E) of three articles, article 1 with dense inner tuft of long setae; article 2 twice as long as article one with one short and one long (as long as article) inner setae; article 3 as long as article 2, with three long distal setae and two rows of shorter setae along distal half of inner margin. Right mandible ( Fig. 8 D) without lacinia mobilis, pars incisiva denticulation complex, setiferous lobe with additional short, rounded spine. Maxillule ( Fig. 8 F) inner endite with outer apophysis, four plumose and one compound distal setae, outer endite with ten distal spines and two subdistal setae, outer margin finely setose distally, palp lost during dissection. Maxilla ( Fig. 8 G) typical of Pakistanapseudes , moveable endite outer lobe outer setal pair densely setulose proximally, inner lobe with five densely plumose setae; fixed endite outer lobe with three compound and two bilaterally denticulate distal spines; rostral row of 32 setae, five longer, plumose caudal setae. Labium ( Fig. 8 H) with outer and distal setose margins, palp with inner apophysis, dense inner and outer fine setulation and two simple distal spines.

Maxilliped ( Fig. 8 I) with simple setae. Palp article 1 with longer, inner distal seta reaching distal margin of article 2, and two shorter outer setae; article 2 with inner margin bearing numerous longer and shorter setae largely in three rows, inner distal row of six setae, and short outer distal seta not reaching tip of article 3; article 3 with nine recurved setae on inner­distal margin; article 4 with seven longer recurved setae on inner­distal margin. Endite ( Fig. 8 I’) distally with simple outer setae, bifurcate mesial setae, slender, blunt inner spines, caudodistal spine stout, bifurcate. Epignath not seen.

Cheliped ( Fig. 9 A) slender. Basis 3.7 times as long as wide, ventrally with four setae in proximal half and paired longer setae distal of midline; dorsally with three simple setae largely in distal half. Three­articled exopodite present; article 3 with four plumose setae. Merus elongate, with rows of inner mesial, mid­ventral and ventral subdistal setae. Carpus very slender, 7.5 times as long as wide, with sparse ventral and inner simple setae longer than carpus width. Chela slender, palm (propodus) twice as long as wide with four distal setae; fixed finger longer than palm, without apophyses but with setules on cutting edge, and three distal and four ventral setae; dactylus as long as fixed finger, curved, with no apophyses on cutting edge.

Pereopod 1 ( Fig. 9 B) with pointed marginal spines. Basis three times as long as wide, with sparse, small dorsal and ventral marginal setae and paired ventrodistal setae, one longer than ischium. Exopodite present. Ischium with four ventrodistal setae. Merus wider distally, with single shorter, ventrodistal spine, setose as figured. Carpus compact, just shorter than merus, longer than wide, with two shorter ventral and one longer dorsodistal spines, heavily setose as figured. Propodus with four ventral marginal spines interspersed with setae, two dorsodistal slender spines amongst sparse setae, dorsal margin only with three setae. Dactylus with three to five small ventral denticulations; unguis distinct, short.

Pereopod 2 ( Fig. 9 C). Basis four times as long as wide, with sparse, small dorsal and ventral marginal setae and four elongate ventrodistal setae twice as long as basis width. Ischium with two long ventrodistal setae. Merus shorter than carpus, with four simple ventral setae, one dorsodistal seta and single ventrodistal pointed spine longer than merus. Carpus with dorsal and ventral seta groups in distal half, as figured. Propodus slender, shorter than carpus, with dorsal and ventral setae groups in distal half. Dactylus slender, longer than propodus; unguis distinct.

Pereopod 3 ( Fig. 9 D). Similar to pereopod 2 but basis naked apart from group of ventrodistal setae, merus and carpus more setose.

Pereopod 4 ( Fig. 9 E). Basis stouter, three times as long as wide, naked apart from paired ventrodistal setae. Ischium with single short dorsal and row of six ventrodistal setae. Merus with ventrodistal setae and one spine. Carpus nearly twice as long as merus, ventrally with numerous setae and three spines largely in distal half. Propodus distal half surrounded by crown of slender setae four spines. Dactylus plus unguis reduced, shorter than adjacent setae, simple; unguis distinct.

Pereopod 5 ( Fig. 9 F). Similar to pereopod 4, but less setose, merus proportionately shorter, dactylus plus unguis longer than adjacent setae.

Pereopod 6 ( Fig. 9 G). Similar to pereopod 5 but propodus ventrodistal margin with dense row of small spines, surrounding distal part of article, dorsodistal group of four slender, blunt spines and three setae. Dactylus plus unguis as long as propodus.

Pleopods ( Fig. 9 H) all alike. Basis with three dorsal plumose setae but no ventral seta. Rami linguiform. Endopod longer than exopod, respectively with 15 and 19 marginal plumose setae.

Uropod: broken (uropod missing from all specimens)

Remarks. Only two previously described species of Pakistanapseudes , plus P. p e r u l p a described above, have a combination of simply rounded rostrum and pigmented eyes. P. ridculli is distinct in bearing bifurcate dactyli on pereopods 2 and 3. P. p e r u l p a has plumose setae on both margins of the pleopod basis, and pleonites 5 and 6 wider than long. P. bassi sp. nov. is closest to the generotype, P. leptochelatus , but that species has far fewer setae on the mandibular palp proximal article, a far shorter dactylus on pereopod 2, fewer setae on the antennal squama, no long dorsodistal spine on the carpus of pereopod 1, and the exopodites of the cheliped and pereopod 1 have only two distal setae.

There are now five species of Pakistanapseudes known from Australia, all discovered in the last two years. That as many as three species were found in close proximity in Moreton Bay suggests that more will be awaiting discovery. The known species may be distinguished by the following key.

Figures

FIGURE 7. Pakistanapseudes bassi sp. nov., holotype female. Scale line = 1.0 mm.

FIGURE 8. Pakistanapseudes bassi sp. nov., paratype female, A, antennule; B, antenna; C, left mandible; D, right mandible incisor; E, mandible palp, F, maxillule; G, maxilla; H, labium; I, maxilliped; I’, maxilliped endite Scale line = 0.1 mm.

FIGURE 9. Pakistanapseudes bassi sp. nov., paratype female, A, cheliped; B­G, pereopod 1 ­ 6 respectively; H, pleopod. Scale line = 0.1 mm.