Nedsia douglasi, 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 : 199-201

Nedsia douglasi n.sp.

Figs 24-26

Etymology. Named for the collector of the material.

Type locality. Ned's Well, Yardie Creek , North West Cape, Western Australia.

Material examined. HOLOTYPE (Western Australian Museum, WAM 7-64 ), female "g" 4.77 mm, in the type series collected August 1963, A.M. Douglas collector. Other material from type series (PARATYPES), female "h" 5.08 mm, female "i" 4.38 mm and 26 other specimens (no males) .

Diagnosis. As in the genus.

Description of holotype (female "g"). Body (Fig. 24): urosome poorly armed dorsally; length, 4.74 mm.

Head (Fig. 24): rostrum obsolescent; eyes absent.

First antenna (Fig. 24): length about 0.6 of body (broken), 2.4 second antenna, flagellum longer than peduncle, peduncular article 1 longest, article 3 shortest, setae sparse, flagellum with many articles, no calceoli, no aesthetascs; accessory flagellum 2-articulate, second article tiny, articles of primary flagellum uniform, sparsely setulate. Second antenna (Fig. 24): length 0.25 body; peduncle longer than flagellum, articles 4-5 equally long, articles 3, 4 and 5 with weak ventral setation, article 3 without dorsomedial spines; flagellum 4-articulate, lacking calceoli.

Upper lip (Fig. 24): apical margin excavate, connection to epistome and bulbous epistome itself slightly asymmetrical. Left mandible (Fig. 24): palp article I shorter than 2, article 2 with 2 apical setae; incisor 5- toothed, lacinia mobilis 5-toothed, 4 setose accessory blades; molar lacking distal plumose seta, no other pubescence. Right mandible: incisor 5-toothed; lacinia mobilis bifid, slender, each flake denticulate; accessory blades of 4 scarcely plumose spines. Right and leftfirst maxillae (Fig. 24): palp article 2 with 7 thin apical and subapical spines, outer plate with 7 spines, most denticulate; inner plate with 6 medial setae. Second maxilla (Fig. 24): outer plate outer apical margin with pubescence, basomedial margin of inner plate with pubescence. Maxilliped (Fig. 24): palp article 3 with pair of thin setae on inner edge; inner plate with 1 ventrofacial spine.

First gnathopod ( Figs 25 , 26 ): coxal plate with short setae apically, without posteroventral spine; article 4 posteriorly bulbous; carpus not lobate; propodus trapezoidal, expanding apically, longer than wide, posterior edge almost naked, corner of palm almost square, with 3 lateral setae and 4 medial spines, palm slightly convex; dactylus reaching end of palm. Palm of second gnathopod ( Fig. 26 ): with 4 lateral and 4 medial spines, spine at palmar corner medial, coxal plate broader and poorly setose.

Pereopods (Figs 24-26): coxa 3 with similar setae, coxa 4 more irregular, with similar setae; pereopods 3- 4 longer than gnathopod 2, pereopod 3 not longer than 4, articles 4-5 sparsely setose posteriorly, posterior margin of article 6 on pereopods 3-4 with armament formula of ES-ES-S-S, thus with only one locking spine; pereopods 5-7 similar but consecutively elongate, each with 2 locking spines; anterior spines on pereopod 7 article 6 displaced inward by keel-like expansion of segment; coxae 5- 7 bearing few setae on ventral margin of posterior lobes, article 2 moderately expanded and not lobate but extended posteriorly, bearing thin short posterior setae; dactyls of pereopods 3-7 simple, naked except for outer basal penicillate setule. Gills of coxae 2- 6 flask-shaped, of pereopod 6 not reduced. Oostegites strap-shaped, poorly setose.

Epimera ( Fig. 26 ): each epimeron posteroventrally quadrate (softly), posterior margins scarcely convex, smooth and barely setulose, epimera 1- 3 with 1-3-6 ventrofacial spines, lacking lateral oblique ridge. Pleon (Figs 24, 26): only pleonites 2 and 5 with dorsolateral posterior seta, pleonite 6 with 2 dorsolateral and 2 distoventral spinules; uropod 3 extending well beyond uropods 1 and 2 in entire animal, uropod lengths relative to uropod 1: uropod 2 = 0.5, 3 = 1.33. Pleopods: retinacula 2 per pleopod, one accessory: peduncles each with 1 apicolateral seta, rami extending subequally, outer with 10-9-8 articles, inner with 10-9-8 articles, setae on basal articles = 1-1-1-1 for all rami, none bifid.

First uropod ( Fig. 26 ): peduncle length 1.3 rami, 1 basofacial spine, outer margin with 1 apicodistal spine besides row of 3 dorsal spines, with 2 apicomedial spines: rami of subequal length, both rami with 2 sparsely filled rows of marginal spines. Second uropod ( Fig. 26 ): peduncle about 1.1 length of inner ramus, with 2 apicodorsal spines, 2 dorsolateral spines, medial margin with 2 apical spines: outer ramus shorter than inner, both with 2 rows of marginal spines in formula of 1-1 and 1-3, apices of rami on uropods 1-2 with 4 -6 and 4- 5 spines. Third uropod ( Fig. 26 ): peduncle length 0.28 outer ramus, shorter than urosomite 3, with subdistal seta besides apicolateral cluster of 5 spines; outer ramus proximal article with several irregular spine-setal ranks, article 2 shorter but similarly armed; inner ramus length 0.12 of outer, with 2 apical spines, left uropod 3 regenerant. Telson ( Fig. 26 ): 1.2 as long as wide, as long as urosomite 3; cleft 100 percent of its length; apices minutely notched, subapices each with 3 long setae, 3 other dorsal setae and 2 lateral setae on each lobe, each lobe with single penicillate setule dorsolaterally at M.60.

Description of other material. Specimen "h": female, length 5.08 mm. Mandibular palps (Fig. 24) with 2- 3 apical setae on article 2. Telson less setose apically than holotype.

Specimen "i": female, length 4.38 mm. Head, right lacinia mobilis and mandibular palp illustrated (Fig. 24).

Distribution. Western Australia, North West Cape, in well.

Figures

Fig. 25. Nedsia douglasi n.sp., holotype, female "g" 4.77 mm.

Fig. 26. Nedsia douglasi n.sp., holotype, female "g" 4.77 mm (all drawings except those indicated); female "h" 5.08 mm.