Galaxias brevissimus, 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 : 48-53

Galaxias brevissimus , new species

Short-tail Galaxias

Tables 4 to 9, 12, 15 to 16; Figures 7 & 12

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

Material Examined.

Holotype. NMV A.30559-3, 77.2 mm LCF, (69.6 mm SL), female, Jibolaro Creek, at bridge on Tuross Rd, north-west of Kybeyan , New South Wales, 36° 14' 01”S 149° 27' 10”E, T.A. Raadik, 14 March 2002.

Paratypes. NSW: AMS I.44914-001 (1), 79.8 mm LCF (71.3 mm SL) and NMV A.30559-1 (4), 71.9–95.5 mm LCF (64.2–86.7 mm SL), collected with holotype.

Non-type material. NSW: NMV A.30559-2 (3), 49.4–55.9 mm LCF (44.0– 49.9 mm SL), collected with holotype.

Diagnosis. Galaxias brevissimus sp. nov. differs from all other species within the Galaxias olidus complex by a combination of the following characters: short caudal peduncle (10.3–12.0 % SL) and caudal fin length (10.1–12.2 % SL); anal fin and pelvic fins set far back at about 76 and 53 % SL respectively; anal and dorsal fin lengths short and dorsal fin base short (8.0–9.6 % SL); small pectoral fin (9.6–12.0 % SL); dorsal midline of trunk usually flattened anteriorly from above midpoint between pectoral and pelvic fin bases; head quite narrow (55.9–59.6 % HL) and eye relatively large (18.3–21.0 % HL); nostrils moderately long, not visible from ventral view; gape about as wide as length of lower jaw; often a single, sometimes two, unbranched, segmented rays in the dorsal fin (versus usually 2); low mean number of vertebrae (52); raised lamellae on the ventral surface of paired fins appear to be absent; caudal peduncle flanges relatively short, occasionally just reaching adpressed anal fin; single, moderately short (1.7 % SL) and thin pyloric caecum; anal fin origin usually under 0.8 distance posteriorly along dorsal fin base; gill rakers sharply pointed; and, lack of black bars along lateral line.

Description. As for the genus and members of the Galaxias olidus complex, except as indicated below, based on 6 specimens, 64.2–86.7 mm SL, and 3 additional, non-type specimens for meristics. See Tables 4 to 9 for frequencies of meristic values and Table 15 for a summary of meristic variation. Segmented dorsal fin rays 9 (9–10), of these 8 (7–8) branched and 1 (1–2) unbranched; segmented anal fin rays 11 (10–12*), of these 9 (8*–10) branched and 2 unbranched; caudal fin rays 16 (16–17); segmented pectoral fin rays 15 (13–16; [14*]), of these 13 (11–14; [12*]) branched and 2 unbranched; pelvic fin rays 7, of these 6 branched and one unbranched; gill raker total count (lower limb and upper limb) 12 (10–13; [11*]), lower arch with 9 (8–10) and 3 (2–3) on upper, variation on first gill arch 8+2 (2), 9+2 (2*), 9+3 (4), 10+3 (1); vertebrae 52 (51–52); one pyloric caeca on stomach.

See Table 16 for comparative value ranges of morphometric characters. Body moderately elongate and shallow, dorsal midline usually flattened anteriorly from above midpoint between pectoral and pelvic fin bases, depth through pectoral base about 1.2 that through vent, trunk with dorsal and ventral profiles slightly but evenly arched from snout to dorsal fin, body tapering back to a short, 9.1 (8.3–9.7) in SL, caudal peduncle of moderate depth, 12.5 (12.0–13.0) in SL, the peduncle depth 1.4 (1.3–1.6) in its length; accessory lateral line present. Head of moderate depth, 2.3 (2.1–2.4 in HL) and length, 4.5 (4.3–4.8 in SL), length 1.1 (1.0–1.3) in PelAn length, narrow, 1.7–1.8 in HL, and distinctly wider than deep (depth 1.3 in HW), lateral profile wedge-shaped, flattened dorsally; eyes of moderate size, 5.1 (4.8–5.5) in HL and 2.2 (2.1–2.3) in HD, situated high on head just below dorsal head profile, interorbital flat to slightly convex, of moderate width, 2.6–2.7 in HL and 1.9–2.0 times ED; cheeks expanded only very slightly below eyes, eye profiles clearly visible laterally from ventral view; snout of moderate length, 3.4 (3.2–3.6) in HL and 1.5–1.7 times ED, lateral profile slightly blunt; post-orbital head length of moderate length (1.8 in HL); nostrils moderately long, not visible anterio-laterally from ventral view; mouth generally terminal, of moderate length, 2.7 (2.6–2.9) in HL, posterior extent reaching under anterior 0.3 of eyes and about 0.64 (0.59–0.69) of ED below ventral margin of eye, most anterior tip of upper lip usually just above level with middle of eye, gape of moderate width, 2.8 (2.7–3.0) in HL, width 0.9–1.0 that of length of upper jaw and 1.6–1.7 in HW. Jaws subequal, lower a little shorter (1.0– 1.1 in UJL). Pyloric caeca moderately short, averaging 1.7 % SL (1.2–2.4 %), thin and rounded on the end; gill rakers short and stout, sharply pointed.

Fins relatively thin, slightly 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 and anal fins bases of moderate length, dorsal base usually 1.0–1.2 times length of anal base, fins short and rounded, usually of similar length though anal sometimes slightly longer, middle rays the longest, anal fin origin usually set back under 0.77 (0.68–0.89) distance along dorsal fin base. Pelvic fins small, 10.6 (10.1–11.1) in SL, usually 0.84 of pectoral fin length, inserted just posterior to midpoint of standard length (0.52–0.55 of SL) and extending about 0.4 (0.34–0.45) distance to anal fin base; pectoral fin small and paddle-shaped, usually 8.8 (8.3–10.4) in SL, extending just over 0.35 distance to pelvic fin base, low on body with dorsal extent of fin base usually level with posterior extent of mouth, lamina of paired fins tending to face ventrally, raised lamellae not present on ventral surface of rays. Caudal fin short, 8.8 (8.2–9.9) in SL, emarginate, about same length as caudal peduncle, vertical width of expanded rays greater than body depth through pectoral base, flanges low and moderately developed along caudal peduncle, extending only slightly anteriorly, occasionally reaching distal end of adpressed anal fin rays.

except for LCF and SL).

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Size. Recorded to 95 mm LCF and 7 g; commonly to 70–75 mm LCF.

Colour in life. Body predominantly brown on back and upper sides above lateral line, extending onto top and sides of head and snout, becoming lighter brown on lower lateral sides of trunk to light brown or cream ventrally. Overlain by small to moderately large, irregularly shaped dark brown to almost black profuse blotches and spots, some coalescing to form larger patches, Gill cover translucent, brownish; iris coppery; fins dusky. See below for more detailed comments on body pattern.

Colour of preserved material. Base colour of head and body light brown to tan. Small to moderately large, irregularly shaped and faded spots, blotches and bands densely spaced on dorsal surface of trunk, extending down sides to below lateral line, also extending across entire depth of caudal peduncle, very faded to absent from head. Trunk patterning overlain by very fine, pale brown stippling, also extending downs sides and onto head.

Eye dark grey to black, pupil translucent pale orange-yellow. Teeth translucent yellow to pale orange-yellow, tips orange to orange-red; gill rakers cream. Fins generally pale tan to cream, becoming more translucent on posterior margins. Fin rays translucent.

Etymology. Latin brevissimus , meaning shortest, small, in reference to this species having the shortest caudal peduncle and caudal fin compared with other members of the Galaxias olidus complex. Suggested vernacular name as the ‘Short-tail Galaxias’.

Genetics. Allozyme and mtDNA analysis of this species can be found in Adams et al. (2014; taxon code JI). Diagnostic allozyme loci (7–15) 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 Jibolaro Creek, a tributary in the very upper reaches of the Tuross River system in southern, coastal New South Wales, at an elevation of 950 m asl. The location is approximately 12 km (river distance) from the source, which is at 1190 m asl, in a catchment of approximately 27 km 2. Downstream distribution unknown; considered to have been historically more widespread, extending a considerable distance farther downstream before predatory trout reduced and fragmented its range.

Sympatry. Only species of Galaxias found within its restricted range. However Galaxias brevipinnis is known from lower to mid reaches of the Tuross River system, farther downstream. Also see under ‘Remarks’.

Habitat. Recorded from a clear and gently flowing, unshaded, narrow and shallow (1.0 m average width and 0.3 m average depth) creek, consisting predominantly of pools connected by very short sections of shallow riffles. Substrate consisted of clay overlain by fine and coarse sand, with areas of silt, and riparian vegetation had been cleared and consisted of pasture and tussock grass. Instream cover was provided by rock, aquatic vegetation and overhanging grasses and maximum pool depth was 0.9 m. The general catchment of the creek at the type locality was disturbed, having been previously cleared for grazing. At the time of sampling (0900 hrs, 14 March 2002) the instream dissolved oxygen (DO) concentration was relatively low (4.2 mg /L) and the majority of fish were captured in the shade under the bridge at the head of a pool where, presumably, water of higher DO concentration was flowing in over a short riffle section.

General Biology. Confined to freshwater and considered not to undertake diadromous migrations. Recorded at a relatively high density of 2.15 fish/m 2, though this was probably elevated above normal levels encountered in an undisturbed stream due to fish congregating in shade and accessing higher quality water (see above). Collected with a native species of freshwater crayfish ( Euastacus sp. ), the native Common Freshwater Shrimp and the translocated native Common Yabby ( Cherax destructor ). Spawning period unknown, though all mature fish examined in mid-March were in an early stage of gonad development, with gonads filling from 25–50 % of the body cavity, and the smallest fish collected measuring 49.4 mm LCF, suggesting spawning during late winter/early spring. One individual found with small white cysts, possibly trematode metacercariae, embedded in tissue on the inside of both gill covers.

Conservation status. Considered critically endangered based on IUCN criteria ( ISPS 2013): A2e; B1+2abc; C2a(i)—one location/population, EOO and AOO estimated at 2.7 km 2.

Remarks. Raised lamellae on the paired fins in this species appear to be absent, though only nine individuals were available for examination. Consequently, examination of additional material is required to confidently confirm their absence. Until collected during this study in 2002, galaxiids from the Galaxias olidus complex had not been recorded from the Tuross River system. More recently, additional specimens from the G. olidus complex have been recorded by NSW Fisheries staff from two locations at lower elevations in the Tuross River catchment (Wadbilliga River and New England Creek). These samples, preserved in ethanol and therefore only partially suitable for morphological examination due to shrinkage, have been initially identified as G. olidus based on mtDNA analysis (C. Burridge, pers. comm. 2011). Collection of fresh material is required for a detailed nuclear DNA and taxonomic appraisal.

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 12. A–B: Galaxias brevissimus sp. nov. holotype, NMV A.30559-3, 77.2 mm LCF, Jibolaro Creek, Tuross Rd, northwest of Kybeyan, New South Wales, A) line drawing (R. Plant), B) image of preserved specimen (T.A. Raadik); C) G. brevissimus sp. nov., collected at the type locality with the holotype, 14 March 2002; ~ 80 mm LCF (R. Kuiter); D) Jibolaro Creek, at type locality, 14 March 2002 (T.A. Raadik). Scale bar = 5 mm.