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.