Austrogammarus telsosetosus, 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 : 162-167

Austrogammarus telsosetosus n.sp.

Figs 1 - 4

Etymology. Named for the basalwards extension of setae on the telson .

Type locality. Creek flowing into Lake Bonney, South Australia, beyond wood plant effluent outflow.

Material examined. HOLOTYPE ( Australian Museum , P44058) , female "q" 9.76 mm, in type series collected 21 November 1977, P. & D. Suter collectors, sample number 967 "1: 280, 000 329 390". ALLOTYPE ( Australian Museum , P44059) same sample, male "s" 7.42 mm. Other measured specimens, female "r" (P44060) 9.00 mm and male "t" (P44061) 7.70 mm. Five other specimens (P44062) in same sample. Tributary of Eight Mile Creek , South Australia, 22 November 1977, P. & D. Suter collectors, sample number 969 "1: 50, 000 824 900," juvenile "w" (P44063) 4.95 mm, female "v" 10.70 mm and 5 other specimens. Cress Creek, at Port MacDonnell , South Australia, 22 November 1977, P. & D. Suter collectors, sample number 971, male "u" (P44064) 5.91 mm. Other material: Eight Mile Creek , South Australia, January 1980, Keith F. Walker collector, 9 specimens (P44065) .

Diagnosis. Flagellum of antenna 2 poorly setose and bearing calceoli in male. Coxae 1-4 weakly to not setose ventrally, coxa 4 lacking ventral setae, only with posteroventral setae and several anteroventral setae, coxae 1- 3 with several posterior spines. Coxa 4 with posteroventral lobe unusually weak. Gnathopods dimorphic between the sexes, palmar corners in male not bent outward, with 10 spines. Posterior spines on article 6 of pereopods 3-4 in single sets, without group of setae placed between spine sets 1 and 2, formula thus 2-2-3-2-2-1 (all spines) and 2-4-3-4-3; lateral spine formulae on article 5 of pereopods 3 and 4 = 3-1-2-1 and 4-4-4- 1; article 2 of pereopods 5- 7 with short setae; setae of articles 4-6 of pereopods 5-7 short and of low density; article 4 of only pereopod 7 short. Epimeron 1 without anteroventral setae. Urosomal setation dorsally short and stiff; pleonites 4-5 with 4+ dorsolateral spines on each side, with one or two additional dorsomedial sets of 1- 2 spines, pleonite 6 with 2-4 spines on each side, formulae from medial to lateral on one side only, pleonite 4 = 1-2-4 or 1-1-5, pleonite 5 = 0-2-4, pleonite 6 = 0-2 or 0-4, often with incipiently thickened small spinules in middle of segment; none of uropods 1-2 with setae on peduncles and inner rami, apicolateral corner of peduncle on uropod 1 with 2 spines only, on uropod 2 with 2 spines only, medial spines on peduncle of uropod 1 (distal to proximal = 1-1-1-1), setae in same sets = 0, on uropod 2 = 1-1-1-1 and 0; uropod 3 strongly setose, inner ramus reaching to about M. 33 in female and M. 60 in male on outer ramus, with one subapical spine in female only, apex with many setae and 2 long hooked spines in male placed towards medial side, with 2 widely separated spines in female, medial margin with setae in tandem, lateral margin with setae in male, with spine in female; article 1 on outer ramus with spine sets laterally and medially mixed with setae arranged in clusters, article 2 small, with short apical setae. Telson fully cleft, lobes separable, spinose and setose, setae extending more basalwards than in A. muitispinatus .

Description of holotype (female "q"). Body (Figs 3, 4): p1eon dorsally setose, setation dense and transverse on pleonites 1 -3, setae very short and confined to margins of segments, pleonites 4-6 with spine-seta rows weakly ranked longitudinally but generally in transverse band; length, 9.76 mm.

Head ( Fig. 1 ): eyes absent.

First antenna ( Fig. 1 ): length 0.57 ofbody, 1.3 second antenna, flagellum much longer than peduncle, setae sparse; accessory flagellum 6-7 articulate, reaching past article 7 of primary flagellum. Second antenna ( Fig. 1 ): length 0.40 body; peduncle as long as flagellum, articles 4 and 5 equal in length, articles 3, 4 and 5 with weak ventral setation; flagellum 21 articulate, setose ventrally, lacking calceoli.

Left mandible: setae of palp article 3 = 4, 2A, 3, 5B, many D, 2E; incisor 5-toothed, lacinia mobilis 4- toothed, 6 setose accessory blades; molar ( Fig. 1 ) with short setose spines. Right mandible ( Fig. 1 ): incisor 4- toothed; lacinia mobilis bifid, denticulate: accessory blades of 3 setose spines and vestigial fourth; molar with short plumose seta. Left first maxilla ( Fig. 1 ): palp article 2 with 11 thin apical spines and 4 scarcely subterminal facial setae; inner plate with 13 widely spread medial setae. Right first maxilla ( Fig. 1 ): pa1p article 2 with 8 thick apical spines articulated to segment and one articulate apicolateral spine. Second maxilla ( Fig. 1 ): outer margin of outer plate with one short seta: inner margin of inner plate with strongly submarginal row of many setae.

First gnathopod (Fig. 2): coxal plate sparsely setose marginally, posterior margin with 4 (aberrantly 7) spines; carpus weakly elongate, unlobed; propodus rectangular, longer than wide, posterolateral angle ordinary, palm oblique, curved. Second gnathopod (Fig. 2): slightly longer and thinner than first gnathopod, carpus elongate; coxal plate with 6 posterior spines.

Pereopods ( Figs 1 , 2, 4): coxa 3 with 5 posterior spines, coxa 4 lacking setae below and lacking posterior spines, deeply emarginate, but posterior lobe not as long as in A. multispinatus ; pereopods 3-4 not longer than gnathopod 2, pereopod 3 longer than 4, article 4 moderately setose posteriorly.

Epimera (Fig. 3): all epimera with small posteroventral tooth, each with short posterior setules, epimera I, 2 and 3 with I, 6 and 7 ventrofacial spines. Uropod lengths relative to uropod 1: uropod 2 = 0.60, 3 = 0.73. Pleopods}-3: peduncular setae = successively: 9 apicolateral; 8 apicolateral, 6-4-2 lateral, 4 basomedial; 5 apicolateral, 4-6 basolateral, 4 basomedial; coupling hooks = 2, accessory spines = 2; articles of outer rami = 20-20-19, of inner rami = 17-17-16, setae of basal article for each ramus laterally to medially = 7-2-3-8, 5-3-2-7 and 4-1-1-7.

First uropod (Fig. 3): peduncle length 1.2 x length of rami. Second uropod (Fig. 3): peduncle 1.2 inner rami. Third uropod (Fig. 3): peduncle length 0.37 outer ramus, about same length as urosomite 3; proximal article with 6 medial and 6 lateral transverse spine-setae; inner ramus length 0.33 of outer. Telson (Fig. 4): about as long as urosomite 3; fully cleft; apices strongly setose, dorsum of each lobe with one spine and numerous setae, several of these basal and basolateral setae extending to M.40.

Description of other material. Specimen "t" ( Figs 1 - 4): male: length 7.70 mm; like female but article 5 of antenna 2 (Fig. I) with 4 calceoli, basal articles past article 1 of flagellum each with calceolus (antennae of available males otherwise broken). Propodi of gnathopods (Fig. 2) expanded, carpi shortened, medial defining spines of palm 4, lateral 6. Coxa 4 (Fig. 2) more strongly produced but not as strongly as in A. multispinatus . Peduncle of uropod 3 (Fig. 4) with 3 apicolateral spines (only 2 showing in figure), with 6 ventral spines (not shown); inner ramus reaching to M.60 on outer ramus, apex with 2 hooked spines, medial margin widely setose, article 1 of outer ramus with number of spine-setal ranks much reduced (but body length of male much shorter than in female), medial base more widely setose. Five lateral setae (or setal positions, one positions with 2 setae) on each side.

Specimen "r": female; 9.00 mm; spines on article 5 on pereopod 3 = 5-1-1, on pereopod 4 = 5-1-2-1-0 (last position bearing seta only); total spines on left article 2 of pereopod 3 (proximal to distal) = 2-2-2-2-2, on right pereopod 3 = 1-2-2-1-2, on left pereopod 4 = 2- 2-3-3-2.

Specimen "v": female, 10.70 mm, spines on one side of pleonites 4-6 = 5-4-3.

Specimen "u": male, 5.91 mm, coxa 4 illustrated for varietal shape.

Specimen "w": juvenile, 4.95 mm, urosome (Fig. 3) spine counts on one side of urosomites 4-6 = 2-2-2 or 3-4-2 (variable).

Illustrations. The lower lip and maxilliped are like A. australis but the maxilliped is even more setose and spinose.

Relationship. Differing only slightly from A. multispinatus and perhaps a subspecies of it. The two taxa are separated by a distance of 800 km. Austrogammarus telsosetosus differs fromA. multispinatus in the slightly larger count of dorsal spines on the pleonites in adults, the basalwards extension of setation on the telson and the slightly shorter lobe on coxa 4.

Distribution. South-eastern South Australia just west of border with Victoria, streams (blind, therefore possibly hypogean, living as epigeans only in vicinity of emergent springs).

Figures

Fig. 1. Austrogammarus telsosetosus n.sp., holotype, female "q" 9.76 mm (all drawings except those indicated); male "t" 7.70 mm.

Fig. 4. Austrogammarus telsosetosus n.sp., holotype, female "q" 9.76 mm (all drawings except those indicated); male "t" 7.70 mm.