Nannoperca pygmaea, a new species of pygmy perch (Teleostei: Percichthyidae) from Western Australia

Abstract

A new species of pygmy perch (Percichthyidae) from south-western Australia is described on the basis of 15 specimens collected from the Hay River system. Nannoperca pygmaea sp. nov. differs from the sympatric congener N. vittata (Castelnau) by the absence of dark pigment on the ventral surface anterior to the anus, the possession of thin latero-ventral stripes, generally fewer dorsal rays and fewer anal rays, hind margin of scales on caudal peduncle without distinct pigment, and a more pronounced spot (ocellus) that is surrounded by a halo at the termination of the caudal peduncle. The new species is distinguished from congeners Nannoperca australis Günther, N. oxleyana Whitley and N. variegata Kuiter and Allen in possessing an exposed and serrated preorbital bone and jaws that may just reach to below the anterior margin of the eye, versus a smooth and hidden preorbital and the jaws reaching to at least below the pupil; and from the remaining congener, N. obscura (Klunzinger) in possessing a distinct haloed ocellus at base of caudal fin versus an indistinct barring, as well as a dark spot behind operculum, and the lack of dusky scale margins. It differs from the other sympatric pygmy perch found in the region, N. balstoni Regan, by the presence of an exposed rear edge of the preorbital (vs. hidden under skin), fewer transverse scale rows (13 vs. 15-16), small mouth (rarely reaching eye vs. reaching well beyond eye), ctenoid (vs. cycloid) body scales, generally fewer pectoral rays and smaller maximum size. Allozyme analyses unequivocally demonstrate that sympatric populations of N. pygmaea sp. nov. and N. vittata belong in different genetic lineages, display no genetic intermediates, and are diagnosable by fixed allozyme differences at 15 different loci. Due to its extremely restricted range, where it is known from only 0.06 km2, N. pygmaea sp. nov. requires urgent legislative protection.

Full text

Accepted by R. Pethiyagoda: 4 Mar. 2013; published: 12 Apr. 2013
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ISSN 1175-5326 (print edition)
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Copyright © 2013 Magnolia Press
Zootaxa 3637 (4): 401–411
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http://dx.doi.org/10.11646/zootaxa.3637.4.1
http://zoobank.org/urn:lsid:zoobank.org:pub:155F0E3D-5EC3-4ED5-8C92-61834E56D8AF
Nannoperca pygmaea, a new species of pygmy perch (Teleostei: Percichthyidae)
from Western Australia
DAVID L. MORGAN
1
, STEPHEN J. BEATTY
1
& MARK ADAMS
2
1
Freshwater Fish Group & Fish Health Unit, School of Veterinary & Life Sciences, Murdoch University, South St, Murdoch, Western
Australia, 6150, Australia. E-mail: D.Morgan@murdoch.edu.auS.
Beatty@murdoch.edu.au
2
Evolutionary Biology Unit, South Australian Museum, North Terrace, Adelaide, South Australia, 5000, Australia.
E-mail: Mark.Adams@samuseum.sa.gov.au
Abstract
A new species of pygmy perch (Percichthyidae) from south-western Australia is described on the basis of 15 specimens
collected from the Hay River system. Nannoperca pygmaea sp. nov. differs from the sympatric congener N.vittata (Castel-
nau) by the absence of dark pigment on the ventral surface anterior to the anus, the possession of thin latero-ventral stripes,
generally fewer dorsal rays and fewer anal rays, hind margin of scales on caudal peduncle without distinct pigment, and
a more pronounced spot (ocellus) that is surrounded by a halo at the termination of the caudal peduncle. The new species
is distinguished from congeners Nannoperca australis Günther, N. oxleyana Whitley and N. variegata Kuiter and Allen
in possessing an exposed and serrated preorbital bone and jaws that may just reach to below the anterior margin of the eye,
versus a smooth and hidden preorbital and the jaws reaching to at least below the pupil; and from the remaining congener,
N. obscura (Klunzinger) in possessing a distinct haloed ocellus at base of caudal fin versus an indistinct barring, as well
as a dark spot behind operculum, and the lack of dusky scale margins. It differs from the other sympatric pygmy perch
found in the region, N. balstoni Regan, by the presence of an exposed rear edge of the preorbital (vs. hidden under skin),
fewer transverse scale rows (13 vs. 15–16), small mouth (rarely reaching eye vs. reaching well beyond eye), ctenoid (vs.
cycloid) body scales, generally fewer pectoral rays and smaller maximum size. Allozyme analyses unequivocally demon-
strate that sympatric populations of N. pygmaea sp. nov. and N. vittata belong in different genetic lineages, display no
genetic intermediates, and are diagnosable by fixed allozyme differences at 15 different loci. Due to its extremely restrict-
ed range, where it is known from only 0.06 km
2
, N. pygmaea sp. nov. requires urgent legislative protection.
Key words: sympatric species, Nannoperca vittata, Nannatherina balstoni, Hay River, Mitchell River, South West Coast
Drainage Division, endemic fishes
Introduction
The pygmy perches, Nannoperca and Nannatherina, are represented by six species that are restricted to southern
Australia and are placed either within the Nannopercidae (e.g. Allen 1989, Kuiter et al. 1996, Allen et al. 2002) or
Percichthyidae (e.g. Kuiter & Allen 1986, Jerry et al. 2001, Paxton et al. 2006, Unmack et al. 2011). Jerry et al.
(2001) demonstrated that the pygmy perches are monophyletic with Macquaria and placed them within the
Percichthyidae. Jerry et al. (2001) and Kuiter et al. (1996) suggest that the pygmy perch genus Edelia should be
incorporated with Nannoperca, based on molecular genetic criteria and reflecting minor anatomical differences,
such as the posterior margin of the preorbital bone being either hidden by skin (Edelia) or exposed (Nannoperca),
however Allen et al. (2002) and Paxton et al. (2006) retain Edelia. Jerry et al. (2001), based on 12S rRNA, found
no basis for recognising Edelia, with E. vittata and E. obscura being unmistakably sister taxa to Nannoperca
australis, N. oxleyana and N. variegata. Unmack et al. (2011) in their phylogenetic revision of the pygmy perches
support the use of Nannoperca for all species of pygmy perch except Nannatherina balstoni.
We accept that there are currently three described endemic species of percichthyid in south-western Australia
belonging to three genera, Nannoperca, Nannatherina and Bostockia (Fig. 2b, c, d) (Morgan et al. 1998, Jerry et al.

MORGAN ET AL.
402 · Zootaxa 3637 (4) © 2013 Magnolia Press
2001, Allen et al. 2002, Unmack et al. 2011). This region encompasses the South West Coastal Drainage Division
(Fig. 1), and contains the highest proportion of endemic freshwater fishes of all of Australia’s major drainage
divisions (Morgan et al. 1998, Allen et al. 2002). Eight of the 10 freshwater fish species are endemic, including all
three species of percichthyid, Nannoperca vittata, N. balstoni and Bostockia porosa. Nannatherina balstoni is
extremely rare throughout its range (Morgan et al. 1995, 1998, Morgan 2009) and is listed in Australia under the
Environmental Protection and Biodiversity Conservation Act 1999 as vulnerable (Morgan 2009). The remaining
two percichthyids are much more widespread but have undergone considerable range reductions due to loss of
habitat, secondary salinisation of habitats and competition with introduced fishes (Morgan et al. 1998, 2003, 2004,
Beatty et al. 2011).
Unmack et al. (2011) demonstrated that N. vittata shows extensive genetic heterogeneity across its range, and
suggest that this is indicative of there being multiple species at the catchment scale. Sampling of fishes in the Hay
River catchment (Fig. 1) during 2009 revealed three morphologically and phenotypically distinctive forms of
pygmy perch (Fig. 2). This included two described species, N. vittata and N. balstoni, and a further form that
appeared to be a distinct yet undescribed species. The latter fish most closely resembled N. vittata, having a small
mouth that rarely reaches beneath the anterior margin of the eye (although the maxilla may just reach it), whereas
N. balstoni has a mouth that extends beyond the anterior margin of the eye, the maxilla reaching to beneath the
middle of the eye. While morphological characters have historically been used to assess the taxonomic status of
phenotypically distinctive forms, it is now common practice to use a combination of both morphological and
molecular genetic characters for this purpose. We therefore include both genetic and morphological data in the
description of this newly discovered pygmy perch from south-western Australia.
FIGURE 1. Sampling sites, in the South West Coastal Drainage Division, Western Australia. Both sites 1 and 2 in the Mitchell
River and in the Quickup River are in close proximity to each other.
PERTH
PERTH
PERTH
PERTH
PERTH
PERTH
PERTH
PERTH
PERTH
Quickup
River
Marbelup Brook
Hay River
Mitchell River
0
King RiverKing River
10 20 km
Kalgan River
Goodga
River
Angove
River

South West Coastal
Drainage Division
AUSTRALIA
Southern Ocean
Southern Ocean
Southern Ocean
Southern Ocean
Southern Ocean
Southern Ocean
Southern Ocean
Southern Ocean
Southern Ocean
Southern Ocean
Southern Ocean
Southern Ocean
Southern Ocean
Southern Ocean
Southern Ocean
Southern Ocean
Southern Ocean
Southern Ocean
Indian Ocean
Indian Ocean
Indian Ocean
Indian Ocean
Indian Ocean
Indian Ocean
Indian Ocean
Indian Ocean
Indian Ocean

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NANNOPERCA PYGMAEA SP. NOV.
Materials and methods
Capture sites and morphological and meristic counts. A total of 20 sites was sampled throughout the Hay River
catchment (Fig. 1), with the undescribed species of pygmy perch only captured at three adjacent sites including: (1)
the lower section of the Mitchell River ~300 m upstream of the confluence with the Hay River (34
o
53.15’S,
117
o
29.27’E), (2) in the Hay River at the confluence of the Mitchell River (34
o
53.27’S, 117
o
29.14’E), and (3) in the
Hay River (34
o
53.28’S, 117
o
29.45’E) ~500 m upstream of site 2. Using the methodology for morphometric
measurements and meristic counts as given in Kuiter and Allen’s (1986) synopsis of the Australian pygmy perches
which includes the original description of Nannoperca variegata, a total of 15 individuals was assessed and
compared to 22 sympatric N. vittata from these sites. Comparisons were then made between the undescribed
species and relevant published information including that detailed in Kuiter and Allen (1986), Allen (1989), Kuiter
et al. (1996) and Allen et al. (2002). Type specimens have been deposited in the Western Australian Museum
(WAM) and the South Australian Museum (SAM).
Allozyme procedures. Muscle tissues were collected from 13 individuals representing the two morphotypic
forms found in the Hay River catchment. These tissues were immediately frozen on site in liquid nitrogen and later
stored at -70
o
C until required for allozyme analysis. Reference tissues representing all other populations of N.
vittata from rivers including and to the east of the Hay River catchment (n = 28) were obtained from the Australian
Biological Tissue Collection, housed at the SAM.
Allozyme electrophoresis of muscle homogenates was undertaken on cellulose acetate gels (‘Cellogel’,
M.A.L.T.A., Milan) according to the principles and procedures detailed in Richardson et al. (1986). The following
enzymes or non-enzymatic proteins displayed bands of sufficient activity and resolution to allow allozymic
interpretation:- ACON, ACP, ACYC, ADA, ADH, AK, ALD, ALDH, AP, CA, CK, ENOL, EST, FDP, FUM,
GAPD, GLO, GOT, GP, G6PD, GPI, GSR, IDH, LAP, LDH, MDH, ME, MPI, NDPK, PEP-A, PEP-B, PEP-D,
PGAM, 6PGD, PGK, PGM, PK, and TPI. Enzyme and locus abbreviations, electrophoretic conditions and stain
recipes are described elsewhere (Richardson et al. 1986, Hammer et al. 2007). Allozymes were designated
alphabetically and multiple loci, where present, were designated numerically, both in order of increasing
electrophoretic mobility.
As discussed in detail elsewhere (Horner and Adams 2007), the assessment of species boundaries using
allozyme data is best undertaken by initially adopting a multivariate analytic procedure such as Principal Co-
ordinates Analysis (PCA) that employs individuals rather than populations or sites as the unit of analysis. Unlike
site-based assessments, PCA allows both within-site and between-site heterogeneity to be concurrently assessed,
and also facilitates the identification of hybrids and of individuals bearing the genetic signature of introgression.
An initial PCA was undertaken on a pairwise matrix of Rogers’ genetic distance among individuals, following the
methodology presented in Hammer et al. (2007). Thereafter, a scatterplot of PCA scores in the first two dimensions
was assessed for the presence of discrete clusters of individuals. The raw genotypes were then examined to
determine if any of these genetic lineages were diagnosable by fixed differences, as would be expected where two
clusters represent different biological (sympatric) or evolutionary (allopatric) species. Relationships among the
genetic lineages identified in the PCA were examined by constructing an unrooted Neighbor Joining (NJ) tree
based on a pairwise matrix of Nei’s unbiased genetic distances among sites, following the methodologies presented
in Hammer et al. (2007).
Results
Systematics
Nannoperca pygmaea sp
. nov.
Little Pygmy Perch
Fig. 2A
Holotype. WAM P.33379–001, 31.6 mm SL, Hay River, Western Australia (34
o
53.28’ S, 117
o
29.45’ E), collected
by D.L. Morgan and S.J. Beatty, 9 September 2009 (Fig. 2).

MORGAN ET AL.
404 · Zootaxa 3637 (4) © 2013 Magnolia Press
FIGURE 2. Percichthyidae of the South West Coastal Drainage Division, Western Australia. A. Nannoperca pygmaea sp. nov.
(WAM P.33380–001, 31.8 mm SL). B. Nannoperca vittata. C. Nannatherina balstoni. D. Bostockia porosa. Bottom, holotype
N. pygmaea sp. nov. Photographs S. Beatty and D. Morgan.

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NANNOPERCA PYGMAEA SP. NOV.
Paratypes. WAM P.33380–001, 10 specimens, 26.8–38.0 mm SL, Mitchell River, Western Australia
(34
o
53.15’ S, 117
o
29.27’ E), collected by D.L. Morgan and S.J. Beatty, 28 October 2009; WAM P.33379.02, 1
specimen, 33.2 mm SL, Hay River/Mitchell River confluence, Western Australia (34
o
53.27’ S, 117
o
29.14’ E),
collected by D.L. Morgan and S.J. Beatty, 9 September 2009; SAM FISHY6: Esp.09001, Esp.09003, Esp.09004
(Fig. 2), 3 specimens, 28.6–38.7 mm SL, Mitchell River and Hay River confluence, Western Australia (34
o
53.27’
S, 117
o
29.14’ E), collected by D.L. Morgan and S.J. Beatty, 9 December 2009.
Diagnosis. A species of Nannoperca in having a small mouth, a deeply notched dorsal fin, a poorly developed
two-part and interrupted lateral line. It is distinguished from the congeneric N. australis, N. oxleyana and N.
variegata in possessing an exposed and serrated preorbital bone and the jaws may just reach to below the anterior
margin of the eye, versus possessing a smooth and hidden preorbital and the jaws reaching to at least the pupil. It is
distinguished from N. vittata by: the possession of 5–10 thin lateral stripes most obvious below lateral line; poorly
developed tube scales versus well developed in N. vittata; a more distinct haloed blackish spot resembling an
ocellus at the base of the caudal fin; the hind margin of the scales on the caudal peduncle are without distinct
pigment as in N. vittata; and the belly is without a colour pattern. It is distinguished from N. obscura in possessing
a distinct ocellus at the base of caudal fin versus an indistinct barring, as well as a dark spot behind operculum and
lack of dusky scale margins. It is distinguished from the other sympatric pygmy-perch species in the region, N.
balstoni, in possessing an exposed rear edge of the preorbital (compared to being hidden under the skin in N.
balstoni), has fewer transverse scale rows (13 vs. 15–16), a smaller mouth (rarely reaching eye vs. reaching well
beyond the eye), ctenoid body scales (vs. cycloid), generally fewer pectoral rays and a smaller maximum size.
Description. Dorsal-fin rays holotype VIII, 8 (paratypes VII–IX, 8 or 9); anal-fin rays III, 6 (paratypes III, 6 or
7); pectoral-fin rays 11 (paratypes 10 or 11); body scales ctenoid; lateral-line scales with marginally developed
tubes; lateral line scales 18+13; horizontal scale rows at level of anal fin origin 13–15; gill rakers on first arch 3+7
(2–3 + 5–7); jaw just reaching to below anterior part of eye. Body relatively slender, laterally compressed, greatest
body depth 3.0 (2.7–3.4) in SL. Head relatively short with pointed snout, its length 3.3 (2.9–3.6) in SL. Following
proportions are in head length: snout length 4.7 (3.9–6.2), exposed maxilla length 4.9 (4.3–6.2), eye width 3.5 (3.3–
3.9), interorbital width 3.6 (3.1–4.0), caudal peduncle depth 1.7 (1.5–2.1), caudal peduncle length 1.2 (1.1–1.4),
caudal fin length 1.3 (1.2–1.6), pectoral fin length 1.7 (1.4–2.1), pelvic fin length 1.7 (1.5–1.9), first dorsal spine
length 3.3 (2.8–4.2), first anal spine length 5.5 (4.7–8.0), second anal spine length 2.7 (2.3–3.1), third anal spine
length 3.0 (2.5–3.9) (Tables 1, 2 and 3).
Longest dorsal spine 2nd, longest soft dorsal ray 3rd or 4th, longest soft anal ray 2nd or 3rd, pelvic and
pectoral fins usually equal in length. Reduced blackish spot behind edge of gill cover, coloration on ventral surface
anterior to anus limited to one or two dark melanophores, a distinct ocellus at base of caudal fin, fins often orange,
large brownish dorso-lateral blotches often merging, series of brownish mid-lateral blotches commencing behind
operculum, terminating on caudal peduncle; hind margin of scales on caudal peduncle without distinct pigment;
two spines on hind margin of operculum, almost equal; 5–10 thin lateral stripes most obvious below lateral line,
tube scales poorly developed.
Coloration in preservative. Generally pale fins and lateral and dorso-lateral blotches light to dark brown in
colour except for ventral surface, which appears opaque, thin ventro-lateral stipes more prominent than in live
specimens, opercular spot distinct, haloed ocellus on caudal peduncle at base of caudal fin very distinct.
Etymology. The specific epithet pygmaea is the feminised form of the Latin noun pygmaeus meaning “dwarf”
applied as a noun in apposition, and in reference to this being the smallest of the pygmy perches. Common name
Little Pygmy Perch applied in recognition of the relative small size.
Genetic assessment. The final allozyme dataset comprised genotypes at 56 putative loci for 41 fish from nine
sites, and included sympatric series of both N. pygmaea (n = 8) and N. vittata (n = 8) from the Hay River
catchment. An initial PCA (Fig. 3) clearly demonstrated the presence of two major genetic lineages, diagnosable by
a complete absence of shared alleles at 15 different allozyme loci (Table 4). The absence of heterozygous
individuals at any of the 15 diagnostic loci demonstrates that these two lineages do not interbreed in sympatry and
display no evidence of introgression in allopatry, i.e. the unequivocal genetic signature of different biological
species. The NJ tree among populations (Fig. 4) further demonstrates their genetic distinctiveness. The two species
display a mean Nei D of 0.34, considerably larger than the maximum between-population value of 0.06 within N.
vittata.

MORGAN ET AL.
406 · Zootaxa 3637 (4) © 2013 Magnolia Press
TABLE 1. Mean and range (in parentheses) of proportional external measurements of Nannoperca vittata and type specimens
of Nannoperca pygmaea sp. nov. from the Mitchell/Hay River catchment, expressed as a percentage of standard length (SL).
TABLE 2. Dorsal and anal fin-ray counts for Nannoperca spp. and Nannatherina balstoni (N. vittata and N. pygmaea from this
study, others and N. vittata from Kuiter and Allen (1986)).
Discussion. Nannoperca pygmaea represents the third species of pygmy perch (and the fourth percichthyid)
discovered in Western Australia. The number of endemic freshwater fishes of Australia’s South West Coast
Drainage Division is now nine and the proportion of endemic species in the region now stands at 82%; the highest
of any Australian drainage division. A recent molecular overview of pygmy perches (Unmack et al. 2011) revealed
evidence for two very distinct genetic lineages among a handful of N. vittata populations further to the west and
north of the Hay River catchment. Unmack et al. (2011), based on genetic evidence, suggest that one of the two
lineages warrants elevation to species status pending morphological diagnosis. Thus it is likely that there are at
Species Nannoperca vittata Nannoperca pygmaea
number of fish n = 22 Holotype Paratypes n = 14
mean (range) SL (mm) 40.02 (28.1–50.7) 31.6 32.38 (28.6–38.7)
Total length (TL) 121.58 (115.58–127.01) 124.7 123.69 (116.4–128.3)
Greatest body depth 33.97 (30.29–39.59) 29.7 33.2 (29.1–36.5)
Head length 31.19 (27.45–33.78) 28.3 30.8 (28.2–34.3)
Snout length 6.64 (5.80–8.09) 5.8 6.8 (5.0–9.3)
Maxilla length 7.11 (5.36–8.42) 5.9 6.3 (4.8–7.3)
Eye diameter 8.02 (6.98–9.16) 7.5 8.7 (7.8–10.1)
Caudal peduncle length 22.85 (20.73–27.56) 25.9 24.8 (21.6–26.6)
Caudal peduncle depth 16.89 (14.28–21.78) 18.4 17.9 (15.6–19.8)
Pectoral fin length 18.30 (15.57–22.22) 17.5 18.5 (15.0–22.0)
Pelvic fin length 18.48 (16.84–20.44) 17.5 18.3 (16.3–20.2)
Length of dorsal fin base 34.70 (32.30–36.19) 33.0 33.6 (29.2–39.0)
Length of anal fin base 15.43 (13.30–17.51) 12.7 14. 9 (11.9–17.9)
Caudal fin length 22.23 (20.06–27.65) 23.1 23.3 (20.2–25.2)
1st dorsal spine length 9.29 (7.26–12.15) 7.6 9. 5 (7.5–11.8)
2nd dorsal spine length 19.25 (16.80–21.85) 17.9 18.9 (16.3–21.1)
Longest dorsal spine length 2nd 2nd 2nd
Longest soft dorsal ray 3rd 3rd 3rd or 4th
1st anal spine length 5.93 (4.88–7.11) 5.2 5.7 (3.7–6.2)
2nd anal spine length 11.42 (9.27–13.36) 10.4 11.6 (10.1–13.5)
3rd anal spine length 9.76 (7.99–11.24) 9.4 10.2 (7.9–11.5)
Longest soft anal ray length 3rd or 4th 3rd 2nd or 3rd
Dorsal spines Soft dorsal rays Soft anal rays
VIVIIVIIIIX 7891011678910
N. pygmaea 16 8 105 510
N. australis 11459 2 1 19488 2 38351
N. obscura 8 24 3 25 4 7 24 1
N. oxyleyana 2271 1 254 255
N. variegata 19 2 14 7 10 11
N. vittata 3 38 2 6 26101 4 363
N. balstoni 2162 1712 1154

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NANNOPERCA PYGMAEA SP. NOV.
least four species of pygmy perch in this region, long recognised as one of the planet’s hotspots for biodiversity and
endemism (Myers et al. 2000).
TABLE 3. Pectoral-fin ray and gill raker (lower limb of first arch) counts for Nannoperca spp. and Nannatherina balstoni (N.
vittata and N. pygmaea from this study, others and N. vittata from Kuiter and Allen (1986)).
FIGURE 3. Principal Co-ordinates Analysis (PCA) of Nannoperca vittata from six river systems (Mitchell (Hay) River,
Marbelup Brook, King River, Kalgan River, Angove River, Goodga River) and Nannoperca pygmaea genotyped in the
allozyme study. The relative PCA scores have been plotted for the first (X-axis) and second (Y-axis) dimensions, which
individually explained 65% and 9%, respectively, of the total multivariate variation. See Fig. 1 for site localities.
Habitat and conservation considerations. Explanation of how N. pygmaea evaded discovery for so long lies
in the fact that its habitats are only seasonally accessible by vehicle and it has an extremely narrow range. In terms
of distribution, N. pygmaea is the most restricted species of pygmy perch, currently known from a geographical
area of only 0.06 km
2
, and a stream length of 1.2 km. It is one of Australia’s most geographically restricted
freshwater fish species. Its habitats are tannin stained, acidic and shallow Melaleuca rhaphiophylla streams (Fig.
5). Flow is seasonal, characteristic of this ‘Mediterranean Climatic’ region, with the site on the Mitchell River
drying out each summer. Although the Mitchell River supports intact natural vegetation, much of the Hay River
catchment is cleared of its natural vegetation (52%). The pools on the Hay River are therefore critical summer
Pectoral rays Gill rakers
10 11 12 13 14 15 3 4 5 6 7 8 9 10
N. pygmaea 312 1 1 9 1
N. australis 4 40 30 2 5 23147
N. obscura 2236 4124
N. oxyleyana 1229 6818
N. variegata 1563513
N. vittata 21018 10 1 5 229
N. balstoni 137 221132

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408 · Zootaxa 3637 (4) © 2013 Magnolia Press
refuges for the species, although the catchment is becoming increasingly affected by secondary salinisation (Mayer
et al. 2005). For example, between 1993 and 2002 the mean salinity of the Hay River was 2300 mg.L
-1
, which was
an overall increase of 400 mg.L
-1
from the previous decade (Mayer et al. 2005). Although mean conductivity in the
Mitchell River generally remains below 0.5 mS.cm
-1
, the type locality in the Hay River increases in mean
conductivity from <2.9 mS.cm
-1
in winter and early spring, to almost 11 mS.cm
-1
in late summer as these habitats
decrease in size to small isolated pools. Stream secondary salinisation is a recognised threat to south-western
Australia’s freshwater fishes (Morgan et al. 2003), and while the salinity tolerance of N. pygmaea is unknown, it is
likely to be similar to the sympatric pygmy perches N. balstoni and N. vittata, which have acute tolerances of 8.2
and 14.6 g.L
-1
, respectively (Beatty et al. 2011). Mean winter temperatures are ~12
o
C, increasing to over 23
o
C in
summer. As a consequence of the rarity and restricted geographic range of N. pygmaea, the species requires urgent
protection at the state and federal level.
FIGURE 4. NJ tree based on pairwise Nei Ds among sties for Nannoperca vittata in seven catchments (Angove River, Goodga
River, King River, Mitchell/Hay River, Kalgan River, Quickup River and Marbelup Brook) and Nannoperca pygmaea in the
Mitchell/Hay River. See Fig. 1 for site localities.

Zootaxa 3637 (4) © 2013 Magnolia Press · 409
NANNOPERCA PYGMAEA SP. NOV.
TABLE 4. Allele frequencies for all variable loci at the sites sampled for Nannoperca vittata and N. pygmaea. Frequencies of
all but the rarer/rarest alleles are expressed as percentages and shown as superscripts (allowing the frequency of each rare allele
to be calculated by subtraction from 100%). The allozyme loci, which diagnose N. pygmaea from N. vittata, are identified with
an asterisk. Nannoperca vittata sites are referred to by the following abbreviations: AN = Angove R., GO = Goodga R., KA =
Kalgan R., KI = King R., QU#1 and QU#2 = Quickup R., MH = Mitchell and Hay R. (N. pygmaea is sympatric with N. vittata
at site MH#2). See Fig. 1 for site localities. Invariant loci: Acp, Ald1, Ap, Ca1, Ck, Enol1, Gapd1, Gapd2, Glo, Gp1, Gp2, Gsr,
Idh, Ldh1, Mdh1, Mpi, Ndpk, Pgam, Pgk, Pgm, Pk1, Pk2, and Tpi1.
Locus AN
(3)
GO
(3)
KA
(4)
KI
(4)
MA
(5)
QU#1
(3)
QU#2
(3)
MH#1
(3)
MH#2
(5)
N. pygmaea
(8)
Acon1*b b
b
75
,a b
75
,a b
70
,d
bb b
b
90
,a
c
Acon2 bbbbbbb
b
83
,a
bb
Acon3 aa
b
62
,a a
88
,b b
70
,a b
50
,a
33
,c a
50
,b
aba
Acyc b bbb b
b
83
,a
bbbb
Ada* aaaaaaa aab
Adh1 a aaa a
a
67
,c a
83
,c
a
a
90
,b
a
Adh2 bbbbbb
b
83
,a
bbb
Ak bbbbbbb
b
83
,a
bb
Ald2
b
83
,a b
83
,a
bbbbb bbb
Aldh bbbbbbb b
b
90
,a
b
Ca2* aaa
b
75
,a a
80
,b
aa
b
67
,a a
63
,b
c
Enol2 cc
c
87
,a
ccc
c
83
,b
ccc
Est1*bbbbbbb bba
Est2*aaaaaaa aab
Fdp
b
67
,a a
50
,b b
62
,a b
62
,a
bbb bba
Fum* bbbbbbb bba
G6pd*aaaaaaa aab
Got1*bbbbbbb bba
Got2*aaaaaaa aab
Gpi1
b
67
,a a
50
,b
b
b
87
,a
bbb bb
b
94
,c
Gpi2*b
b
67
,c b
50
,c b
75
,a
13
, c e
60
,c
30
, b e
50
,c
33
, a c
33
,d
33
, a
17
,e e
66
,c
17
, a c
60
,a
20
, e
f
Lap* bbccccc cca
Ldh2 b bbb
b
90
,a
bb bbb
Mdh2 a aaa
a
90
,b
a
a
67
,c
a
a
90
,b
a
Me1*
b
83
,a
bbbbbb bbc
Me2 bb
b
87
,a
bbbb bb
b
75
,c
Pep-A1 a aaa
a
90
,b
aa aaa
Pep-A2 bbb
b
87
,a
bbb bbb
Pep-B* aaaaaaa aab
Pep-D1* aaaaaaa aab
Pep-D2 b bbb
b
90
,a
bb b
b
90
,a
b
6Pgd* cc
c
87
,a
cccc ccb
Tpi2
c
83
,b
c
c
87
,a c
87
,a
ccc ccc

MORGAN ET AL.
410 · Zootaxa 3637 (4) © 2013 Magnolia Press
FIGURE 5. Type locality of Nannoperca pygmaea at the confluence of the Mitchell and Hay Rivers.
Acknowledgements
We thank the Water Corporation of Western Australia for funding the initial project; Ron McLean for project co-
ordination; and Mark Allen for field assistance. Thanks to the Western Australian State NRM for funding recent
work. Thanks also to Peter Unmack and Michael Hammer for providing tissue samples of N. vittata; Alan Lymbery
for providing inputs to study; and to reviewers including Gerry Allen for valuable comments.
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