Chillagoe thea, 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 : 187-192

Chillagoe thea n.sp.

Figs 18-20

Etymology. Named for the type locality.

Type locality. Tea Tree Cave, from freshwater pool III cave, Chillagoe , Queensland.

Material examined. HOLOTYPE (Australian Museum, P44066) , female "k" 5.81 mm, in type series collected 22 August 1973, A. V. Spain collector. Other material from type series ( PARATYPES), female "I" (P44067) 4.98 mm, female "m" (P44068) 5.27 mm, female "n" (P44069, unmeasured), juvenile "0" (P44070) 3.80 mm and 23 other specimens (P44071, no males) . Other material: same locality, 23 August 1973, A.v. Spain collector, 9 specimens (P44072) .

Diagnosis. As in the genus.

Description of holotype (female "k"). Body (like Protocrangonyx in Williams & Barnard, 1988, fig. 63): pleon poorly armed dorsally, armament bilateral, total dorsal setae on pleonites 1 -3 = 2-4-4, spinules on pleonites 4-6 = 2-2-0; length, 5.8 mm.

Head: rostrum obsolescent; eyes absent.

First antenna: length 0.53 of body, 1.6 second antenna, flagellum longer than peduncle, peduncular article 1 longest, article 3 shortest, setae sparse, distoventral corner of article 1 with strong spine, flagellum with 17 articles, lacking conspicuous aesthetascs, accessory flagellum 2-articulate, reaching middle of article 2 of primary flagellum, articles uniform after first 4, sparsely setulate. Second antenna: length 0.33 body; peduncle longer than flagellum, articles 4-5 of equal length, articles 3, 4 and 5 with poor to moderate ventral setation; flagellum 5-articulate, poorly setose ventrally, lacking calceoli.

Upper lip ( Fig. 18 ): apical margin evenly rounded, connection to epistome and epistome itself symmmetrical, epistome with anterior keel. Lower lip ( Fig. 18 ): without inner lobes. Left mandible ( Fig. 18 ): palp article 3 [aberrant], article 2 with 7 medial marginal setae; incisor 5-toothed, lacinia mobilis 4-toothed, 4 setose accessory blades; molar bearing plumose seta, several penicillate hooked brushy basal setae, other pubescence. Right mandible ( Fig. 18 ): incisor 4-toothed; lacinia mobilis bifid, narrow, denticulate; accessory blades of 7 plumose spines, palp article 3 shorter than 2, setae = 15D, 3E. Left first maxilla ( Fig. 18 ): palp article 2 with 7 thin apical spines and 1 barely subterminal facial seta, outer plate with 9 spines, most denticulate; inner plate with 2 apicomedial setae. Rightfirst maxilla ( Fig. 18 ): palp article 2 with 5 thick apical and medial spines fully articulated to segment, one thin seta apicolaterally. Second maxilla ( Fig. 18 ): outer plate outer apical margin without spinule, apicomedial margin of inner plate with 1 weakly submarginal thick seta. Maxilliped ( Fig. 18 ): palp article 3 with sparse ranks of thin setae on inner edge, no lateral setae, face with linear row of 3 setae, apex not strongly produced, not rugose; inner plate with 2 thick spines and several plumose setae apically, medial row of 3 plumose setae, and 1 ventrofacial spine; outer plate with 8 thick spines medially.

First gnathopod ( Fig. 18 ): coxal plate with 3 short setules anteroapically, with 1 posteroventral setule; article 4 without posterior hump; carpus thick, short, lobate; propodus subrectangular, longer than wide, posterolateral angle rounded, posterior edge with 3 acclivities and 3 sets of setae, with 2 medial and 5 lateral spines, one lateral spine elongate, palm oblique, convex; dactylus reaching end of palm. Second gnathopod ( Fig. 19 ): of similar size to gnathopod 1; article 5 short and lobate but longer than on gnathopod 1, article 6 more evenly rectangular, palm oblique, palmar corner with 5 lateral and 4 medial spines, posterior margin with 5 setose acclivities; dactyl strongly curved, fitting palm; setation of coxal plate like coxa 1.

Pereopods ( Figs 19 , 20 ): coxa 3 with 6 anterior setae and one posteroventral setule, coxa 4 barely emarginate, with 8 anteroventral and 3 posteroventral setae; pereopods 3-4 not longer than gnathopod 2, pereopod 3 scarcely longer than 4, article 4 weakly setose posteriorly, article 5 weakly spinosetose posteriorly, posterior spine formula = se-se-s-2se and se-se-s-2se, posterior margin of article 6 on left pereopod 3 with spine formula of 2-2-2-2-2-1- 2, on right = 2-2-2-2-2-2, on pereopod 4 = 2s-2s-2se-2se- 2s; pereopods 5-7 similar, each with 2 locking spines; coxae 5- 7 bearing spines or setae on posteroventral margin of posterior lobes, article 2 expanded and lobate posteroventrally, thinner on pereopod 7, bearing thin short posterior setae; dactyls of pereopods 3 -7 with one main spinule, one facial setule at nail margin plus tiny accessory setule rudiments. Gills ( Fig. 20 ) of coxae 2- 6 sausage shaped, of pereopod 6 not reduced. Oostegites slender but lacking setae, shrivelled basally and appearing short.

Sternal (gills) processes ( Fig. 19 ): segments 2-6 with sausage-shaped sternal gills in central pairs.

Epimera ( Fig. 20 ): each epimeron posteroventrally subquadrate, posterior margins scarcely convex, with 1-

2 posterior setules, epimeron 1 with 1 ventral setule, epimera 2 -3 with facial spine formula of 2-2. Pleon ( Fig. 20 ): each dorsolateral posterior margin of pleonites 1-3 with following setal formula, 1-2-2, pleonites 4- 6 with dorsolateral spine formula of 1-1-0. Uropod 3 strongly extending beyond uropods 1 and 2 in entire animal, uropod lengths relative to uropod 1: uropod 2 = 0.50, 3 = 0.86. Pleopods: retinacula 2 per pleopod, no accessories; peduncles without setae, outer rami shorter than inner by length of 2 inner articles, outer with 10-10-9 articles, inner with 8-8-8 articles, setae on basal articles = 1-1-1-2 on all pleopods, none bifid.

First uropod ( Fig. 20 ): peduncle length 1.2 rami; 1 large basofacial spine on outer face; outer margin with 3 apicodistal spines besides row of 4 dorsal spines, with 1 apical spine medially; rami of subequal length, only inner ramus with 2 rows of marginal spines in formula of 2-2, with outer ramus with 2 ventromedial spines, each ramus with 4 apical spines. Second uropod ( Fig. 20 ): peduncle about 0.75 length of inner ramus, with 1 dorsolateral spine, 2 apicals, medial margin with one apical spine; outer ramus shorter than inner, with 2 dorsomedial spines, only inner ramus with 2 rows of marginal spines in formula of 2-2, apices each with 5 spines. Third uropod ( Fig. 20 ); peduncle length 0.28 outer ramus, longer than urosomite 3, with one medial seta, one dorsolateral and 2 ventrolateral spines; outer ramus proximal article with 5 lateral and 5 medial ranks of 2 -3 spines each, apicolateral corner with 2 spines, apicomedial corner with 5 spines; article 2 small. Telson ( Fig. 20 ): 1.25 longer than wide, scarcely shorter than urosomite 3; cleft 70 percent of its length; apices each with spine in notch, 1 apical setule, and each lobe with pair of penicillate setules dorsolaterally at M.70.

Notes of minor items on holotype: left mandibular palp article 2 with 7 medial setae, one seta on apicodorsal corner unlike right palp, setae of article 3 = 4D, 3E.

Description of other material. Specimen "1": female, length 4.98 mm. Left mandibular palp article 3 with setal formula of 14D, 4E (thus left palp on holotype is abnormal); left article 6 of pereopod 3 with posterior spine formula of 2-1-2-2-2-2-2; epimeron 1 lacking posterior setule, face of epimeron 2 with only 1 spine, epimeron 3 lacking direct posterior setule, one at corner present; inner ramus of uropod 1 with 3 marginal spines; lateral margin of ramus on uropod 3 with only 4 sets of spines.

Specimen "0": juvenile, length 3.80 mm. Epimeron 1 lacking ventral spine, epimera 2-3 each with 1 facial spine, only one posteroventral spine; uropod 1 as in holotype, uropod 2 like holotype but outer ramus with only 1 marginal spine, inner ramus formula, lateral = 0-1, medial = 1-1; outer ramus of uropod 3 with only 4 lateral sets of spines.

Specimen "m" ( Figs 18 , 19 ): female, length 5.27 mm.

Distribution. Queensland, Chillagoe, Tea Tree Gully , from freshwater pool in cave.

"Melitoid" Genera

Figures

Fig. 18. Chillagoe thea n.sp., holotype, female "k" 5.81 mm (all drawings except those indicated); female "m" 5.27 mm.

Fig. 19. Chillagoe thea n.sp., holotype, female "k" 5.81 mm (all drawings except those indicated); female

Fig. 20. Chillagoe thea n.sp., holotype, female "k" 5.81 mm.