Galaxias tantangara, Raadik, 2014

Raadik, Tarmo A., 2014, Fifteen from one: a revision of the Galaxias olidus Günther, 1866 complex (Teleostei, Galaxiidae) in south-eastern Australia recognises three previously described taxa and describes 12 new species, Zootaxa 3898 (1), pp. 1-198 : 142-147

Galaxias tantangara , new species

Stocky Galaxias

Tables 4 to 9, 37 & 38; Figures 7 & 35

Conforms to the allozymically defined and morphologically diagnosed taxon ‘TA’ of Adams et al. (2014), and ‘tantangara’ of Raadik (2011).

Material Examined.

Holotype. NMV A.30578-2, 86.3 mm LCF, (75.7 mm SL), female, Tantangara Creek, tributary, above falls 200 m upstream of ford on Alpine Creek Fire Trail, Kosciuszko National Park , upstream of Tantangara Reservoir , New South Wales, 35° 50' 23”S 148° 34' 04”E, T.A. Raadik, 16 March 2002.

Paratypes. AMS I.44917-001 (3), 79.6–86.7 mm LCF (70.5–76.0 mm SL) and NMV A.30578-1 (11), 74.6–102.7 mm LCF (65.5–91.5 mm SL), collected with holotype.

Non-type material examined (not measured): see Appendix 5.

Diagnosis. Galaxias tantangara sp. nov. differs from all other species within the Galaxias olidus complex by a combination of the following characters: low mean total gill raker count of 10; body distinctly stocky and deep through vent and pectoral fin base (12.6–15.6 and 14.9–17.9 % SL); caudal peduncle deep (8.5–10.2 % SL); head obtuse to slightly bulbous in lateral profile, moderately deep (41.4–48.2 % HL) but wide (63.4–72.8 % HL); gape wide (40.2–51.0 % HL and 59.6–72.2 % HW); eye profiles usually not visible laterally from ventral view; nostrils short, not visible from ventral view; caudal fin weakly emarginate to truncate, about as long or slightly longer than caudal peduncle, vertical width of expanded rays usually equal to body depth through pectoral fin base; caudal peduncle flanges long, reaching more than half distance to anal fin base; anal fin long (16.3 % SL); most posterior extent of mouth 0.8 ED below ventral margin of eye; dorsal midline usually flattened anteriorly from above or slightly posterior to pectoral fin bases; raised lamellae absent from ventral surface of rays of paired fins; anal fin origin usually under 0.73 distance posteriorly along dorsal fin base; usually 2, occasionally 1, relatively thin and long (4.7 % SL) pyloric caecae; gill rakers short to very short; and, lack of distinct black bars along lateral line.

Description. As for the genus and members of the Galaxias olidus complex, except as indicated below, based on 15 specimens, 75.7–91.5 mm SL. See Tables 4 to 9 for frequencies of meristic values and Table 37 for a summary of meristic variation. Segmented dorsal fin rays 10 (8–11), of these 8 (6–9*) branched and 2 (1*–2) unbranched; segmented anal fin rays 11 (10–12), of these 9 (8–11) branched and 2 (1–3) unbranched; caudal fin rays 16 (15–16); segmented pectoral fin rays 14 (13–15), of these 12 (11–13) branched and 2 (1–2) unbranched; pelvic fin rays 7, of these 6 branched and one unbranched; gill raker total count (lower limb and upper limb) 10 (9–12; [11*]), lower arch with 8 (7–9*) and 2 (1–3; [2*]) on upper, variation on first gill arch 7+2 (1), 8+1 (1), 8+2 (8), 8+3 (1), 9+2 (3*), 9+3 (1); vertebrae 54 (53–56; [55*]); two*, very occasionally one, pyloric caecae on stomach.

See Table 38 for comparative value ranges of morphometric characters. Body stout, moderately long but deep, body depth through pectoral fin base 5.7 (5.6–6.7) in SL, dorsal midline usually flattened anteriorly from above or slightly posterior to pectoral fin bases, depth through pectoral base 1.2 (1.1–1.3) that through vent, with dorsal profile evenly arched from snout to dorsal fin, ventral profile flattish to slightly arched from snout to anal fin; body tapering back to a deep, 11.1 (10.3–11.7) in SL, caudal peduncle of moderate length, 7.9 (7.0–8.8) in SL, the peduncle depth 1.4 (1.2–1.6) in its length; accessory lateral line present. Head of moderate length, 4.6 (4.4–4.8) in SL, and depth, 2.2 (2.1-2.4) in HL, just shorter than PelAn distance, relatively wide, 1.5 (1.4–1.6) in HL, distinctly wider than deep, depth 1.5 (1.4–1.6) in HW, lateral profile obtuse to slightly bulbous, with dorsal and ventral profiles sloping slightly anteriorly; eyes moderate, 5.3 (4.9–5.7) in HL, situated well below dorsal head profile, interorbital flat to convex, of moderate width, 2.7 (2.4–2.9) in HL and 2.0 (1.8–2.3) times ED; cheeks expanded below eyes, eye profiles usually not visible laterally from ventral view; snout moderately long, 3.5 (3.2–3.8) in HL and 1.5 (1.3–1.7) times ED, lateral profile bluntly rounded; post-orbital head length of moderate length, 1.8 (1.7–1.9) in HL; nostrils short, not visible anterio-laterally from ventral view; mouth usually terminal to very slightly subterminal, moderately long, 2.6 (2.3–2.8) in HL, posterior extent reaching back to under about 0.3 (0.2–0.4) ED and 0.8 (0.7–0.9) ED below ventral margin of eye, most anterior tip of upper lip level with middle of eye or occasionally slightly lower, gape wide, 2.2 (2.0–2.5) in HL, about 1.2 times wider than length of upper jaw and 1.5 (1.4–1.7) in HW. Jaws subequal, lower slightly to distinctly shorter than upper, 0.9 (0.8–0.9 of UJL). Pyloric caecae long, longest averaging 4.7 (3.7–6.1) % SL, relatively thin and rounded to bluntly pointed; gill rakers usually short, or occasionally very short, stout and rounded to bluntly pointed.

Median fins moderately fleshy at bases, paired fins less so, with thickening extending distally over 0.3–0.5 of fin area, extending farther between fin rays, dorsal fin base usually 0.9 (0.8–1.0) in length of anal fin base, fins rounded and relatively low, middle rays longest, anal fin relatively high, 6.1 (5.8–6.9) in SL, longer than dorsal fin; anal fin origin usually under 0.7 (0.6–0.9) distance posteriorly along dorsal fin base. Pelvic fins of moderate length, 9.3 (8.8–10.0) in SL, usually 0.8 (0.8–0.9) of pectoral fin length, inserted at about mid-point of standard length and extending about 0.46 distance to anal fin base; pectoral fin moderately long and paddle-shaped, 7.8 (7.2–8.9) in SL, extending 0.4 distance to pelvic fin base, low on body with dorsal end of fin base level with posterior extent of mouth, lamina of paired fins oriented anterio-ventrally, raised lamellae absent from ventral surface of rays. Caudal fin moderately long, 7.5 (7.1–8.2) in SL, weakly emarginate to truncate, about as slightly longer (1.0–1.1) than caudal peduncle, vertical width of expanded rays usually equal to body depth through pectoral fin base, flanges moderately low and well developed along caudal peduncle, long, reaching anteriorly to more than half distance to fin base along adpressed anal fin rays.

Size. Recorded to 103 mm LCF and 13 g; commonly to 75–85 mm LCF.

Colour in life. Body predominantly dark olive-brown on back and upper sides above lateral line, extending onto top and sides of head and snout, and lateral sides of trunk posterior to anal fin, becoming lighter brown to cream ventrally. Profusely overlain by dark brown to almost black spots and flecks coalescing into small or moderately large, irregular shaped, blotches, particularly widespread on head, extending to snout, under lower jaw, and to near the latero-ventral margin of the gill covers. Gill cover translucent, dusky grey-brown; iris golden; fins translucent dusky grey. See below for more detailed comments on body pattern.

Colour of preserved material. Base colour of head and body pale cream to creamy yellow, with dusky shading on dorsal surface extending downward onto lateral and ventrally surfaces as fine to moderately size, sparse black stippling. Dorsal surface of trunk with bold pattern of closely spaced, grey to dark grey spots and flecks coalescing into small or moderately large, irregular shaped, blotches, extending laterally onto sides; pattern extends across entire caudal peduncle region and flanges, though generally restricted down sides of trunk o just below lateral line, fading abruptly, and extending to ventro-lateral region as faint, light grey blotches. Few very small, almost black vertical bars present along lateral line, more prevalent in anterior trunk region. Spots, blotches and flecks slightly diffuse in outline. Bold trunk pattern extends over dorsal and lateral surfaces of head, extending down cheeks, gill covers, snout and upper jaw onto ventral surface, including underneath anterior portion of lower jaw. Fine to medium, black and brown spotting inside operculum, with fine black spotting on base of and on gill filaments and rakers.

Eye grey to black, pupil translucent pale orange yellow. Teeth translucent yellow to pale orange–yellow, tips orange to orange–red; gill rakers cream to pale yellow. Fins pale creamy yellow, becoming more translucent on posterior margins, fleshy bases of dorsal, anal, and pectoral fins with sparse fine black stippling; faint body pattern extending onto base of caudal fin. Fin rays opaque to translucent, external edges of rays highlighted with very fine black lines or row of fine spots.

Etymology. The specific name tantangara is taken from the small alpine stream from which the type specimens were collected, a tributary of the upper Murrumbidgee River draining from Mount Tantangara. A noun in apposition. Suggested vernacular name as the ‘Stocky Galaxias’.

Genetics. Allozyme and mtDNA analysis of this species can be found in Adams et al. (2014; taxon code TA). Diagnostic allozyme loci (5–12) between this taxon and the other species in the Galaxias olidus complex are provided in Table 12.

Distribution. See Fig. 7 . Only known from the type locality, in the headwaters of Tantangara Creek, upstream of Tantangara Reservoir, NSW, at an elevation of 1360 m asl. Restricted by the presence of trout to a small creek above a waterfall, approximately 4 km (river distance) from the source, which is at 1630 m asl, in a catchment of approximately 4 km 2.

Sympatry. Only species of Galaxias found within its restricted range. Possibly was historically found with Galaxias olidus , which is present farther downstream in the upper Murrumbidgee River system, before alien trout substantially altered distributional patterns in the last 150 years and fragmented and reduced galaxiid populations.

Habitat. Recorded from a small (0.8 m average width and 0.1 m in average depth), cold, clear and fast flowing alpine creek, flowing through an open forest of Eucalypts, low shrubs and tussock grass, which is often snowcovered during winter. Flow consisted predominantly of riffle and glide, with smaller amounts of cascades, and substrate was composed of bedrock, boulder, and cobble, with smaller amounts of pebble and gravel, and sections of silt. Instream cover was provided predominantly by rock and by bank and vegetation overhang, and pools averaged 0.3 m in depth.

General Biology. Confined to freshwater. Recorded at a density of 1.8 fish/m 2 and is the only native fish species so far recorded from within its range. Spawning period unknown, though probably winter: fish collected in mid-March were predominantly at an intermediate stage of gonad development (gonads filling approximately 50 % body cavity), though one male was almost running ripe and one female was close to ripe (gonads filling 75 % of body cavity). Interestingly no juvenile fish were sampled from a 60 m reach of stream during mid-March, with the smallest individual 74.6 mm LCF. Holotype recorded with a short, thin, white worm in the mouth and another from amongst fat deposits around stomach in the body cavity. Able to survive in very cold water (<5 o C) during winter.

Conservation status. Considered critically endangered based on IUCN criteria ( ISPS 2013): A2e; B1+2abc; C2a(i)—one location/population, EOO and AOO estimated at 1.7 km 2.

Remarks. Appear to lack paired fin ray lamellae, a characteristic typical of most species within the Galaxias olidus complex found at high elevations in steep gradient streams with many natural instream barriers. Lamellae may possibly be present in smaller, younger aged fish. A 70 mm SL specimen (AMS IB.745), possibly registered in 1905 and collected from ‘Fantangara Creek [= Tantangara Creek?], Murrumbidgee River, Snowy Mountains, NSW’, may be referable to this species, but is almost completely dried. Another old individual (BMNH 1914.80.20.75), collected from ‘Tantangara Creek, New South Wales’ and examined from a digital image also appears to be referable to this species. Considered to be impacted by alien salmonids, with Brown Trout found immediately below the falls on this system and galaxiids absent from this section. Additional sampling in other headwater tributaries of the Murrumbidgee River, upstream of Tantangara Reservoir, is urgently needed to define the overall distribution and abundance of this apparently rare species, particularly concentrating on small tributary streams above instream barriers which may protect populations from predatory trout. Considered to have been historically more widespread throughouty the upper Murrumbidgee River system before trout reduced their range.

Figures

FIGURE 7. Distribution of Galaxias aequipinnis (open circles), Galaxias brevissimus (grey square), Galaxias gunaikurnai (black square), Galaxias lanceolatus (grey circle), Galaxias longifundus (black diamond), Galaxias mcdowalli (inverted black triangle), Galaxias mungadhan (open squares), Galaxias supremus (open triangle), Galaxias tantangara (grey triangle), and Galaxias terenasus (black circles) (river basins shown—refer to Fig. 1).

FIGURE 35. A–B: Galaxias tantangara sp. nov. holotype, NMV A.30578-2, 86.3 mm LCF, female, Tantangara Creek, tributary, above falls 200 m upstream Alpine Creek Fire Trail, Kosciuszko National Park, New South Wales, A) line drawing (R. Plant), B) image of preserved specimen (note: head and tail curve to right in horizontal plane) (T.A. Raadik); C) detail of head pattern (right hand side) of G. tantangara sp. nov. holotype (T.A. Raadik); D) Tantangara Creek, tributary, facing upstream to type locality of G. tantangara sp. nov., which is above the waterfall, 16 March 2002 (T.A. Raadik). Scale bar = 5 mm.