Uroctena whadjukia, 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 : 173-181

Uroctena whadjukia n.sp.

Etymology. From the principal, original Aboriginal tribe of south-western Australia.

Type locality. Wungong System, Chandler Road, creek draining granite outcrop, stop 2.

Material examined. HOLOTYPE ( Western Australian Museum , WAM 16-95 ), male "g" 7.1 mm, in type series collected 16.7.82 by C.M.Austin and B. Knott . ALLOTYPE ( Western Australian Museum ), female "h" 3.60 mm . Other material (PARATYPES) examined, juvenile "j" 1.17 mm, male "k" 7.19 mm. Ten other adults and ten other juveniles in same sample.

Diagnosis. Eyes not visible in preserved specimens. Setae of antennae 1- 2 sparse and short; male antenna 2 weakly pediform, about 1.5 times as thick as antenna 1; propodus of male gnathopod 1 lacking stout posterior spines; article 2 of male gnathopod 2 with about 4 stout posterolateral facial spines in 2 sets and about 3-9 medium-stout anterior spines plus up to 8 setae in specimens with fewer than 5 spines; gnathopods of both sexes not setose as noted in description of U setosa ; telson cleft 70+ percent, each apex with 1 spine and 2 -3 setae, each dorsum or lateral edge with 3 setae. Description of holotype (male "g"). Body (Fig. 9): urosome moderately armed dorsally; length, 7.1 mm.

Head (Fig. 9): rostrum small; eyes in death absent.

First antenna (Figs 8, 9): length 0.6 of body, 1.45 second antenna, flagellum longer than peduncle, peduncular article 1 longest, article 3 shortest, setae sparse, medial face of article 1 with armament formula of SS-eSS-SS-e, flagellum with 24 articles, each article commencing at article 6 with tiny aesthetascs; accessory flagellum 5-articulate, reaching end of article 5 of primary flagellum, articles uniform, sparsely setulate. Second antenna (Figs 8, 9): length 0.40 body; peduncle longer than flagellum, article 4 longer than 5, articles 3, 4 and 5 with moderate ventral setation, article 3 with 3 dorsomedial spines; flagellum 9-articulate, well setose ventrally, lacking calceoli.

Upper lip: apical margin evenly rounded but connection to epistome and epistome itself slightly asymmetrical. Left mandible (Figs 8, 11): palp article 3 shorter than 2, article 2 with 9 medial marginal setae, article 3 with 2A, 2B, 3C, 2 D, 6E; incisor 5-toothed, lacinia mobilis 4-toothed, 6 setose accessory blades; molar bearing plumose seta, several penicillate hooked brushy basal setae, other pubescence, and one chisel spine Right mandible (Figs 8, 9): incisor 4-toothed; lacinia mobilis not bifid, very broad, partly divided into 2 flakes, denticulate; accessory blades of 2 plumose spines, setae of palp article 3 with 2A, 2B, 2C, 6D, 5E. Leftfirst maxilla (Fig. 9): palp article 2 with 6 thin apical spines and 3 barely subterminal facial setae, outer plate with 11 spines, most denticulate; inner plate with 3 apicomedial setae. Right first maxilla (Fig. 9): palp article 2 with 5 thick apical spines partly articulated to segment, one apicolateral thin seta. Second maxilla (Fig. 9): outer plate outer apical margin with 1 small spinule, apicomedial margin of inner plate with 2 weakly submarginal thick setae. Maxilliped (Fig. 8): palp article 3 with ranks of thin setae on inner edge, apical part with rank of 5 thicker setae, apex not strongly produced, not rugose; inner plate with 3 thick spines and several plumose setae apically, long medial row of plumose setae, and 1 ventrofacial spine.

First gnathopod ( Figs 10 , 11 ): coxal plate with long and short setae apically, with 1 posteroventral spine; article 4 without posterior hump; carpus well developed and longer than in U westralis , narrow and not lobate; propodus subrectangular, longer than wide, posterolateral angle rounded, posterior edge with 3 acclivities and 3 sets of setae, with 1 medial and 3 lateral spines, no lateral spine elongate, palm slightly oblique, convex; dactylus reaching end of palm. Second gnathopod ( Fig. 10 ): enlarged; article 2 with 3 medium anterior spines, posterolateral face with 4 spines in 2 sets, article 5 short and lobate, article 6 hugely ovatorectangular, palm oblique, sculptured, palmar corner with 1 lateral and 1 medial spines, posterior margin near corner without spines; dactyl strongly curved, fitting palm; coxal plate well setose, with one posteroventral spine.

Pereopods (Figs 9- 12): coxa 3 with long setae and one posteroventral spines, coxa 4 barely emarginate, with 4 anteroventral, 11 posterior setae and 2 posteroventral spines; pereopods 3-4 not longer than gnathopod 2, pereopod 3 scarcely longer than 4, article 4 well setose posteriorly, article 5 poorly setose posteriorly, posterior spine formula = eS-ESS-4S and EE-SS4S, posterior margin of article 6 on pereopods 3- 4 with spine formula of ES-ES-ES-SS and ES-ES-ESSSS; pereopods 5- 7 similar, each with 3 locking spines and locking seta; coxae 5-7 bearing spines or setae on ventral margin of both lobes, article 2 expanded and lobate posteroventrally, bearing thin medium to long posterior setae; dactyls of pereopods 3-7 with spine formula of 4-4-4-6-(6), pereopod 7 internal formula = 1-1-2-2, thus spines doubled only on pereopod 7. Gills of coxae 2-6 sausage shaped, of pereopod 6 not reduced.

Sternal (gills) processes ( Fig. 12 ): segments 2- 7 with sausage-shaped sternal gills in formula of 1-1-1-2-2-2, gills on segments 2- 6 central, on segment 7 attached to front of lateral edge of segment.

Epimera (Figs 9, 13): each epimeron posteroventrally rounded, posterior margins convex, notched and setose, setae long, epimeron 1 with 1 ventral seta, epimera 2- 3 with setal formula of 1-2-2-2 and 1-3-2-1-1. Pleon (Figs 9, 13): each dorsolateral posterior margin of pleonites 1-6 with following setal formula (s=side, t=top): 1 = st; 2 = st; 3 = st; 4 = 2s, t; 5 = 2s, 3t; 6 = 2t; uropod 3 strongly extending beyond uropods 1 and 2 in entire animal, uropod lengths relative to uropod 1: uropod 2 = 0.75, 3 = 0.80. Pleopods ( Fig. 12 ): retinacula 2 per pleopod, no accessories; peduncles each with 19-19-30 setae, rami extending equally, outer with 13 -15, 11, 10 articles; inner with 10 -11, 9, 9 articles; setae on basal articles = 4-1-1-3, 4-2-1-3, 2-11-2, none bifid, variable on pleopod 1 on right and left members (formula averaged).

First uropod (Fig. 13): peduncle length 1.5 rami; outer margin with 1 apicodistal spine besides row of 10 dorsal spines and one seta between spines 8 and 9, with 1 apical spine medially and row of 4 setae; rami of subequal length, both rami with 2 rows of marginal spines or setae in formula of SS-SS and E-SS, outer ramus with 4 apical and inner ramus with 5 apical spines. Second uropod (Fig. 13): peduncle about 1.5 length of inner ramus, with 5 dorsolateral spines, no apical, medial margin with 2 basal setae in tandem and one large curved apically barbed hook-spine; outer ramus shorter than inner, both with 2 rows of marginal spines in formula of S-S and S-eS, apices with 4 and 5 spines. Third uropod (Fig. 13): peduncle length 0.50 outer ramus, as long as length of urosomite 3, with several lateral ranks of subdistal setae besides apical cluster of 4 setae and 3 spines, apicomedial corner with spine and seta; outer ramus proximal article with outer (but turned ventrally) comb-row of 12 bifid setae, with transverse lateral spine-seta row on body (3S, 2E), medial margin of apex with 4 spines, lateral margin with 2 spines and 4 setae, apex of large article 2 with 4 apical spines and 3 setae; inner ramus length 0.37 of outer, with 2 apical spines. Telson (Fig. 13): broader than wide, shorter than urosomite 3; cleft 70 percent of its length; apices each with spine in lateral notch, 2 -3 apical and 1 apicolateral setae, each lobe with 2 dorsomedial setae and each lobe with pair of penicillate setules dorsolaterally at M.55.

Description of allotype (female "h"). Body (Fig. 8): length, 3.60 mm. Like male but antennae shorter, antenna 2 short and slender, article 5 almost as long as 4; head sinus smaller; coxae slightly taller, coxal setae slightly sparser, bilobation of coxa 7 weaker; gnathopod 2 ( Fig. 10 ) small, similar to but slightly larger than gnathopod I (Fig. 9), carpi of gnathopods 1-2 shorter than on male gnathopod 1, lobation distinct on female gnathopod 2, latter with only I medial spine, 1 lateral defining spine on palm; oostegites of coxae 2 -3 ( Fig. 10 ) large, ovate, of coxa 4 smaller, of coxa 5 very small. Sternal gill formula distinctive ( Fig. 12 ), segments 2 ~ each with pair of more or less central gills, segments 5 -6 each with 2 pairs, each pair lateral, and segment 7 with 1 pair, each member attached laterally. Armaments of epimera (Fig. 13) short and several comprising spines, formula of epimera 1- 3 = E--ES, EE--S, S, e; uropod 3 (Fig. 13) relatively smaller than in male, subdistal armaments sparser, ventrolateral comb of outer ramus absent, replaced by pair of spines in notch, but apex of article 2 better developed, with 7 spines and 3 setae; telson (Fig. 13) more embryonic in appearance, apical spine on each lobe more central, setae fewer but dorsomedial setal pair relatively more basal.

Additional notes of minor items: mandibular palp article 2 with 4 setae, article 3 formula = 3A, 3B, 3D, 5E, left rakers 6; left maxilla 2 palp with 5 thin apical spines and 2 setae; armament formulae on article 5 of pereopods 3 and 4: SS-S-SS and SS-S-SSS, on article 6 = E-ES and ES-ES-SS, dactyls each with 2 spines; locking spines on pereopods 5-7 = 3S+E, dactylar spines = 2-2-4. Formulae on pleopods 1-3: articles of outer rami = 7-7-5, inner rami = 5-5-4, setae on each peduncle = 5-3-5, setae on outer and inner basal articles of outer and inner rami of pleopods 1 -3 = 3-1-1-3, 2- 1-1-2, 1-1-1-2, outer rami shorter than inner. Posteroventral spines on urosomite 1 = 2; uropodal spine and setal formulae: uropod 1 peduncle dorsolateral = S-S-S-S-SES, medially = E--S, outer ramus of uropods 1-2 lateral and medial spines = 1-1 and 0--1, inner ramus = 0-1 and 0-0, apical spines of outer and inner rami of uropods 1-2 = 4-5 and 4-5.

Description of other material. Specimen "k" (Figs 8, 11): male, length 7.19 mm. Slightly more advanced than male "g", pattern of spines on article 2 of gnathopod 2 slightly distinctive (see Fig. 11 ). Flagellum of antenna 1 with 21 articles, of antenna 2 with 10, calceoli absent. Pereopods 5 -6 each with 4 locking spines and one seta, of pereopod 7 with 3 locking spines and one seta. Dorsolateral margin of peduncle on uropod 1 with 12 spines and 2 setae, of uropod 2 with 6 spines and 5 setae.

Specimen "j" is hatchling in brood pouch of female "h". Generally appearance embryonic, body and appendages of swollen appearance, rostrum absent; accessory flagellum 2-articulate, large; flagellar articles of antenna 1 = 5, of antenna 2 = 4; setae of coxae 1-4 = 2-1-1-2; palmar defining spines of gnathopods 1-2 = 1 lateral seta, 1 medial seta and spine; spine formula on article 5 of pereopod 4 = 0-1-1, on article 6 = 0-2; locking spines on pereopods 3 -7 = 2, on pereopod 5 but less so on pereopods 6-7 one spine about two-thirds as long as dactyl, all dactyls with 1 seta and one spine; setae on pleonites 1- 4 = 2 on each side and 1 fully dorsal; on pleonite 5 = 1 lateral each side and 1 fully dorsal; absent on pleonite 6; all rami of pleopods 1-3 with 2 articles each; epimera 1-3 each with only 1 seta each at posteroventral corner; formulae on uropod 1 peduncle apicolateral = 1, uropod 2 = 1; rami of uropods 1 -2 lacking marginal spines, all with 4 apical spines each; peduncle of uropod 3 lacking spines, inner ramus with 1 apical spine, article 1 of outer ramus with 1 apicomedial and 1 apicolateral spine, article 2 with 2 medium and 1 short apical setae; each lobe of telson with 1 apical spine, 1 apicolateral penicillate setule and 2 dorsolateral penicillate setules.

Relationship. This species differs from the type species of the genus, U ajJinis, in the much smaller number of posterolateral spines on article 2 of male gnathopod 2; U ajJinis bears four sets of three to four each, whereas this species has two sets of two each. In this species there are also no spines on gnathopod 2 propodus besides the defining spines, and the dactyl of gnathopod 1 reaches the apex of the palm. Note that many items of U ajJinis are unknown such as setation sizes and patterns on pereopods, uropods, epimera, and medial antenna 1.

Distribution. Western Australia, Wungong System, creek.

Figures

Fig. 10. Uroctena whadjukia n.sp., holotype, male "g" 7.09 mm (all drawings except those indicated); female "h" 3.60 mm.

Fig. 11. Uroctena whadjukia n.sp., holotype, male "go. 7.09 mm (all drawings except those indicated); male "k" 7.19 mm.

Fig. 12. Uroctena whadjukia n.sp., holotype, male "g" 7.09 mm (all drawings except those indicated); female "h" 3.60 mm.