Toulrabia willsi, Barnard & Williams, 1995

Barnard, J. Laurens & Williams, W. D., 1995, The taxonomy of freshwater Amphipoda (Crustacea) from Australian fresh waters: Part 2, Records of the Australian Museum 47 (2), pp. 161-201 : 168-172

Toulrabia willsi n.sp.

Figs 5- 7

Etymology. Named for the explorer William John Wills, 1834-1861.

Type locality. Stream on Mount Toulrab, Stirling Ranges , Western Australia .

Material examined. HOLOTYPE (Western Australian Museum, WAM 15-19 ), female "a" 6.14 mm, in type series collected 22 December 1965 by D.H.D. Edward. Other material examined (PARATYPES), female "b" 5.64 mm. Six other female specimens in same sample .

Diagnosis. As in the genus.

Description of holotype (female "a"). Body (Fig. 5): urosome poorly armed dorsally; length, up to 6.14 mm.

Head (Fig. 5): rostrum obsolescent; eyes absent.

First antenna (Fig. 5): length 0.66 ofbody, 2.1 second antenna, flagellum longer than peduncle, peduncular article 1 longest, article 3 shortest, setae sparse, flagellum with 23 articles, no calceoli, no aesthetascs; accessory flagellum 2-articulate, articles of primary flagellum uniform, sparsely setulate. Second antenna (Fig. 5): length 0.33 body; peduncle longer than flagellum, article 4 longer than 5, articles 3, 4 and 5 with moderate ventral setation, article 3 without dorsomedial spines; flagellum 7-articulate, moderately setose ventrally, lacking calceoli.

Upper lip (Fig. 5): apical margin evenly rounded but connection to epistome and epistome itself slightly asymmetrical. Left mandible (Fig. 5): palp article 3 shorter than 2, article 2 with 6 medial marginal setae, article 3 with 4C, 14D, 3E; incisor 5-toothed, lacinia mobilis 4-toothed, 4 setose accessory blades; molar bearing distal plumose seta, several penicillate hooked brushy basal setae, other pubescence, and pair of immensely setulate chisel spines. Right mandible (Fig. 5): incisor 4-toothed; lacinia mobilis bifid, very broad, each flake denticulate; accessory blades of 2 plumose spines. Rightfirst maxilla ( Fig. 6 ): palp article 2 with 7 thin apical spines, outer plate with 9 spines, most denticulate; inner plate with 2 apicomedial setae. Left first maxilla (Fig. 5): palp article 2 with 5 thick apical spines mostly fused to segment, one apicolateral thin spine and one subterminal apicolateral facial seta. Second maxilla ( Fig. 6 ): outer plate outer apical margin with 1 small spinule, apicomedial margin of inner plate lacking setae. Maxilliped (Fig. 7): palp article 3 with ranks of thin setae on inner edge; inner plate (Fig. 5) with 1 ventrofacial spine.

First gnathopod ( Fig. 6 ): coxal plate with short setae apically, without posteroventral spine; article 4 without posterior hump, carpus weakly lobate; propodus subrectangular, longer than wide, posterior edge widely setose, posterolateral angle rounded, with 1 medial and 2 lateral spines, no lateral spine elongate, palm slightly oblique, convex; dactylus reaching end of palm. Second gnathopod ( Figs 6 , 7): similar; palmar corner with 2 lateral and 1 medial spines, coxal plate similarly setose.

Pereopods ( Figs 6 , 7): coxa 3 with similar setae, coxa 4 emarginate, with similar setae; pereopods 3-4 slightly longer than gnathopod 2, pereopod 3 scarcely longer than 4, article 4 sparsely setose posteriorly, article 5 poorly spinose posteriorly, posterior spine formula = EEEE-EEE, posterior margin of article 6 on pereopods 3- 4 with spine formula of ES-ES-ES-ES-SS and EES-ESES-SS; pereopods 5-7 similar, each with 4 locking spines; coxae 5-7 bearing few setae on ventral margin of posterior lobes, article 2 weakly expanded and lobate posteroventrally, lobe obsolescent on pereopod 7, bearing thin medium to short posterior setae; dactyls of pereopods 3- 7 with accessory spine formula of 1-1-3-5-4. Gills of coxae 2-6 sausage shaped, of pereopod 6 not reduced. Oostegites (Fig. 7) lacking setae except for tiny apicomarginal pits.

SternaI (gills) processes: segments 6-7 with sausageshaped sternal gills in formula of (on one side) 2-1, gills attached to front of lateral edge of segment, pair of gills on sternite 6 arranged transversely, lateralmost gill shorter.

Epimera (Fig. 7): each epimeron posteroventrally quadrate, posterior margins scarcely convex, smooth and setulose, each epimeron with 3 ventral spines and lateral oblique ridge. Pleon: each dorsolateral posterior margin of pleonites 1-6 with following setal-spine formula (s=side, t=top): 1 = Es, 2 = Es, 3 = Es, 4 = Es, 5 = 0, 6 = EtSs; uropod 3 (Fig. 5) not extending beyond uropods I and 2 in entire animal, uropod lengths relative to uropod 1: uropod 2 = 0.66, 3 = 0.50. Pleopods (for specimen "b"): retinacula 2 per pleopod, one accessory; peduncles each with 5+2, 6+2+2+2, and 4+2 setae, rami extending equally, outer with 8-7-6 articles, inner with 5-5-5 articles, setae on basal articles 7-1-1-3, 5-1- 1-2, 3-2-1-2, none bifid.

First uropod (Fig. 7): peduncle length 1.3 rami; outer margin with 1 apicodistal spine besides row of 5 dorsal spines, with 3 medial spines; rami of subequal length, both rami with 1 row of marginal spines. Second uropod (Fig. 7): peduncle about 1.0 x length of inner ramus, with 3 apicodorsal spines, 2 dorsolateral spines, medial margin with 3 spines, basalmost small; outer ramus subequal to inner, both with 2 rows of marginal spines in formula of 3-2, apices of rami on uropods 1- 2 with 5 spines. Third uropod (Fig. 7): peduncle length 0.80 outer ramus, longer than urosomite 3, with subdistal seta besides apical cluster of 3 spines; outer ramus proximal article with several irregular spine ranks, article 2 absent; inner ramus length 0.40 of outer, with 1 apical spine. Telson (Fig. 7): broader than long, shorter than urosomite 3; cleft 60 percent of its length; apices each with 3 spines in facial notches, 1 apicolateral setule, each lobe with pair of penicillate setules dorsolaterally at M.60.

Distribution. Western Australia, Stirling Ranges.

Figures

Fig. 6. Toulrabia willsi n.sp., holotype, female "a" 6.14 mm.