Revisiting Linnaean and Wallacean Shortfalls in Mindanao Fanged Frogs: The Limnonectes magnus Complex Consists of Only Two Species

Abstract

We revisit the question of species diversity among Mindanao Fanged Frogs of the Limnonectes magnus complex consisting of L. magnus, L. diuatus, L. ferneri, and a previously hypothesized putative new species, inferred in the first molecular phylogenetic studies of the genus almost 2 decades ago. Using a multilocus molecular deoxyribonucleic acid sequence data set and comprehensive sampling of 161 individuals from throughout the Mindanao Pleistocene aggregate island complex landmasses (a distinct faunal region of the southern Philippines) we characterize geographically structured genetic diversity, focusing on the phylogenetic placement of individuals from each species’ type locality. We also present new morphometric data from large samples of freshly collected material from the type localities of each included species; together with examination of the name-bearing original type specimens, we conclude that an overestimation of species diversity has occurred and has been exacerbated by the indiscriminate acceptance of the hypothesis of the existence of widespread cryptic species in this group. We place L. ferneri in synonymy with L. diuatus, clarify the identification of the latter taxon with respect to L. magnus, and apply this name to the widespread, generalist, highly variable giant Fanged Frog distributed throughout the Mindanao faunal region of the southern Philippines.

Full text

Herpetological Monographs, 35, 2021, 112–140
Ó2021 by The Herpetologists’ League, Inc.
Revisiting Linnaean and Wallacean Shortfalls in Mindanao Fanged Frogs: The Limnonectes
magnus Complex Consists of Only Two Species
ROBIN KURIAN ABRAHAM
1
,MARK WILLIAM HERR
1
,VIKTORIA V. STERKHOVA
1
,RAYANNA OTTERHOLT
1,2
,CAMERON D. SILER
3
,
MARITES BONACHITA SANGUILA
4
,AND RAFE M. BROWN
1,5
1
Biodiversity Institute and Department of Ecology and Evolutionary Biology, 1345 Jayhawk Boulevard, University of Kansas, Lawrence, KS 66045, USA
2
Haskell Indian Nations University, 155 E Indian Avenue, Lawrence, KS 66046, USA
3
Sam Noble Oklahoma Museum of Natural History and Department of Biology, University of Oklahoma, 2401 Chautauqua Avenue,
Norman, OK 73072, USA
4
Biodiversity Informatics and Research Center, Father Saturnino Urios University, San Francisco Street, Butuan City, 8600 Agusan del Norte, Philippines
ABSTRACT: We revisit the question of species diversity among Mindanao Fanged Frogs of the Limnonectes magnus complex consisting of L.
magnus,L. diuatus,L. ferneri, and a previously hypothesized putative new species, inferred in the first molecular phylogenetic studies of the
genus almost 2 decades ago. Using a multilocus molecular deoxyribonucleic acid sequence data set and comprehensive sampling of 161
individuals from throughout the Mindanao Pleistocene aggregate island complex landmasses (a distinct faunal region of the southern Philippines)
we characterize geographically structured genetic diversity, focusing on the phylogenetic placement of individuals from each species’ type locality.
We also present new morphometric data from large samples of freshly collected material from the type localities of each included species;
together with examination of the name-bearing original type specimens, we conclude that an overestimation of species diversity has occurred and
has been exacerbated by the indiscriminate acceptance of the hypothesis of the existence of widespread cryptic species in this group. We place L.
ferneri in synonymy with L. diuatus, clarify the identification of the latter taxon with respect to L. magnus, and apply this name to the widespread,
generalist, highly variable giant Fanged Frog distributed throughout the Mindanao faunal region of the southern Philippines.
Key words: Geographic radiation; Mindanao Pleistocene aggregate island complex; Stream frogs
ISLAND archipelagos have provided numerous examples of
the evolutionary processes and biogeographic patterns
involved in generating biodiversity, especially the interplay
of geological processes, colonization, and isolation (Paulay
1994; Brown et al. 2013; Brown 2016). Home to numerous
clades of codistributed terrestrial vertebrates (Brown and
Diesmos 2002), the Philippine Archipelago recently has
been the focus of several integrative studies of amphibian
radiations (Setiadi et al. 2011; Blackburn et al. 2013; Brown
et al. 2013, 2015). A particularly interesting group are the
fanged frogs of the genus Limnonectes, which consists of 73
named species distributed across Southeast Asia. This
diverse clade includes 10 described, morphologically diag-
nosable, and noncontroversial (taxonomically unproblematic)
endemic species in the Philippine Archipelago (Evans et al.
2003; Setiadi et al. 2011).
In a previous review, Brown et al. (2013) distinguished
between the archipelago’s partially or fully characterized
adaptive radiations (Brown et al. 2013, 2015) and the
possibly nonadaptive, geographic radiations (Setiadi et al.
2011; Brown and Siler 2014; Brown et al. 2015, 2016). The
latter, loosely defined category (Brown et al. 2013) includes
clades with one or more representative species on each
island bank, or Pleistocene aggregate island complex (PAIC;
Brown and Diesmos 2002; Brown and Guttman 2002). In
these clades, or suites of taxa (in cases of nonmonophyly
[Brown and Guttman 2002; Evans et al. 2003]), species have
been characterized as ecologically similar, with little to no
evidence of a phenotype–environment correlation or within-
island, ecologically associated diversification (Brown et al.
2013; Brown and Siler 2014). Of particular interest are
clades that show a mixture of diversification patterns, with
single ecological generalists on some islands, and evidence of
intraisland diversification, habitat and reproductive mode
specialization, and multiple sympatric species on some
islands (Inger et al. 1986; Alcala and Brown 1998; Brown
and Iskandar 2000; Evans et al. 2003; Setiadi et al. 2011;
Brown et al. 2013, 2015, 2016). One unclear case of
potentially mixed, adaptively versus nonadaptively radiated
frogs are the Philippine Fanged Frogs, genus Limnonectes,
which are comprised of no fewer than three invasions of the
archipelago (Inger 1954; Evans et al. 2003; Brown et al.
2013) and which have differentiated (or ecologically sorted)
into composite communities with conspicuously distinct size
classes (Setiadi et al. 2011).
We undertook this study to estimate the phylogeny of a
Philippine endemic clade comprising Limnonectes magnus
(Stejneger 1910) and related taxa (Inger 1954; Brown and
Alcala 1977; Evans et al. 2003; Siler et al. 2009; Setiadi et al.
2011), with the goal of clarifying species boundaries
(uncertainty around which has slowed the pace of taxonomic
descriptions and recognition of biodiversity, constituting the
so-called ‘‘Linnaean shortfall’’ ; Raven and Wilson 1992) and
characterizing the geographic distributions of these units,
which has been so poorly understood (the ‘‘ Wallacean
shortfall’’; Lomolino et al. 2010).
Limnonectes magnus, a large-bodied Mindanao faunal
region Fanged Frog (male holotype snout–vent length [SVL]
¼113 mm; Stejneger 1910) was described from the mid-
lower-elevation slopes (1200 m above sea level [asl]) of Mt.
Apo, the country’s highest mountain (2954 m asl), located on
southeast Mindanao Island (Fig. 1), at the southern extent of
the archipelago. Brown and Alcala (1977) later named Rana
diuata (¼Limnonectes diuatus; male holotype SVL ¼58.4
mm) from higher elevations of Mt. Hilong-hilong, in the
Diuata Mountain Range (northeastern Mindanao) and Siler
5
CORRESPONDENCE: email, rafe@ku.edu
112

et al. (2009) described Limnonectes ferneri (male holotype
SVL ¼84.3 mm) from the Municipality of Monkayo, Davao
del Norte Province, southeast Mindanao. Aside from Mind-
anao Island proper, large-bodied Fanged Frogs from other
islands of Mindanao PAIC (e.g., Samar, Leyte, Bohol,
Camiguin Sur) have been reported for more than half a
century (Inger 1954; Brown and Alcala 1970) and consis-
tently identified as L. magnus (Siler et al. 2009).
Evans et al. (2003) demonstrated that populations
historically identified as L. magnus may not be a monophy-
letic assemblage, suggesting that a second (assumed then to
be undescribed) species may occupy the Mindanao PAIC
(Brown and Diesmos 2009), including the islands of Basilan,
Bohol, Leyte, Mindanao, Samar, and many smaller islands
(e.g., Biliran, Camiguin Sur, Dinagat, Siargao) associated
with these major landmasses (Fig. 1). Their analyses
FIG. 1.—Maximum-likelihood point estimate, illustrating relationships of Mindanao Pleistocene aggregate island complex (PAIC) Fanged Frogs, inferred
from analysis of 16S mitochondrial gene). Nodal support: black dots ¼strong support (70 maximum-likelihood bootstrap percentages). Sequences from
Evans et al. (2003) correspond to bold branches with colored arrows. For full museum catalog voucher information, see Appendix 1 and Supplemental Fig.
S2.
113
ABRAHAM ET AL.— TAXONOMIC RESOLUTION OF THE LIMNONECTES MAGNUS GROUP

included what Evans et al. (2003) considered to be topotypic
samples of L. magnus (genetic samples, collected at the type
locality: high elevation, Mt. Apo; Stejneger 1910). Referring
to this second, widespread taxon as ‘‘Limnonectes cf.
magnus,’’ the model-based phylogenetic analyses of mito-
chondrial deoxyribonucleic acid (DNA) sequence data of
Evans et al. (2003) revealed that populations from Mindanao
were sister to those from Samar, which were, in turn, most
closely related to the Bohol Island population. Specimens
that Evans et al. (2003) referred to as the widespread lineage
(L.cf.magnus) were genotyped from throughout the
Mindanao PAIC (Fig. 1), including lower-elevation foothills
of Mt. Apo itself. Other than the description of a third
Mindanao PAIC species (L. ferneri Siler, McVay, Diesmos
and Brown 2009), no further progress on this group has been
made and fieldworkers have simply adopted the name L.
magnus for the high-elevation Mt. Apo population and L. cf.
magnus for the widespread low-elevation populations on all
the islands of the Mindanao PAIC faunal region (Plaza and
Sanguila 2015; Sanguila et al. 2016).
Here we leveraged 30 yr of genetic sampling (1990–2020)
from throughout the Mindanao PAIC, including sequences
from specimens reported by Evans et al. (2003) and Siler et
al. (2009) as well as material from the type localities of L.
magnus (Stejneger 1910), L. diuatus (Brown and Alcala
1977), and L. ferneri (Siler et al. 2009). We reconsider
species boundaries within the L. magnus complex (Brown et
al. 2000; Brown and Diesmos 2002) using a mitochondrial
gene fragment (mtDNA: 16S) to screen genetic variation and
guide reduced sampling of three nuclear gene loci for 19
population/species With our combined multilocus phyloge-
netic estimate and consideration of morphometric variation,
we find no support for the continued recognition of L.
ferneri and conservatively conclude that only two species of
large-bodied Fanged Frogs reside in the Mindanao faunal
region: (1) a single widespread low-elevation species
corresponding to true L. magnus (Stejneger 1910) and (2)
a single high-elevation species referable to L. diuatus
(Brown and Alcala 1977; with L. ferneri [Siler et al. 2009]
now relegated to synonymy).
MATERIALS AND METHODS
Sampling, Molecular Data, Alignment, and Phylogenetic
Analyses
We collected DNA sequences from 161 individuals
collected from 49 localities (Appendix I). We sequenced
one mitochondrial gene region corresponding to the
ribosomal ribonucleic acid subunit (16S) and from a
resulting preliminary mitochondrial ‘‘barcode’’ phylogeny
we selected 19 individuals for subsequent gene sequencing
of three nuclear loci: lactase (LCT), carnitine palmitoyl-
transferase II (CPT-2), and pro-opiomelanocortin (POMC).
Primers, polymerase chain reaction methods, thermal
profiles, and sequencing protocols follow Brown et al.
(2013, 2015). We selected closely related outgroup species
on the basis of uncontroversial higher-level phylogenetic
relationships of the family Ranidae (Feng et al. 2017). All
novel sequences were deposited in GenBank (Appendix 1).
The 16S data set (706 base pairs [bp]), including our
sequences and outgroups from GenBank, was aligned using
the default parameters of the MAFFT algorithm (Katoh and
Standley 2013). The combined nuclear data set (LCT, CPT-
2, POMC) for 19 individuals had a length of 2156 bp. To
assess gene congruence, we estimated gene trees with
maximum likelihood using the program RAxML-HPC
v8.0.0 (Stamatakis 2014) and scrutinized trees inferred from
these partitions for the presence of strongly supported
topological conflict. Not finding strongly supported and
conflicting topologies, we felt justified in concatenating our
data (16S þthree nuclear genes; aligned in MAFFT) for
subsequent analyses.
We conducted maximum-likelihood analyses of our
multilocus (16S þthree nuclear genes) data set using the
same partitions but with the GTRþCmodel for each of 200
independent best-tree searches and the rapid-bootstrapping
algorithm. One hundred replicate tree search inferences
were performed, each initiated with a random starting tree.
Nodal support was assessed with 1000 bootstrap pseudor-
eplicates (Stamatakis 2014). We considered nodes to be
strongly supported when bootstrap values were 70% (Hillis
and Bull 1993). For our multilocus data set we performed
additional likelihood analyses using IQ-TREE (Trifinopoulos
et al. 2016), which used 1000 bootstrap pseudoreplicates via
the ultrafast bootstrap approximation algorithm. Ultrafast
bootstrap support values 0.95 indicate well-supported
nodes in IQ-TREE analyses (Minh et al. 2013).
Partitioned Bayesian analyses for the concatenated (16S þ
three nuclear genes) data set were conducted in BEAST 2
(Bouckaert et al. 2014) on the CIPRES gateway server
(Miller et al. 2010). We partitioned the nuclear DNA by
locus, with gene-specific protein-coding regions partitioned
by codon position. The corrected Akaike information
criterion model to find selection parameters and the
‘‘greedy’’ search algorithm for finding the best models for
Bayesian analysis (Darriba et al. 2012) were used to select
the best model of nucleotide substitution for each partition.
We ran four analyses, each with four Metropolis-coupled
chains, an incremental heating of 0.02, and an exponential
distribution with 25 as the rate parameter prior on branch
lengths. All analyses were run for 10 310
6
generations
(sampling every 1000 generations). We set the burn-in to the
default value of 25%, hence discarding the initial 5 310
6
generations. To assess stationarity, we used trace plots and
effective sample size values (.200) on Tracer v1.7 (Rambaut
et al. 2018). We constructed a 50% majority consensus tree
with posterior probabilities estimates of nodal support using
the remaining sampled trees. We considered nodal support
with Bayesian posterior probabilities values 0.95 as
significant (Huelsenbeck and Rannala 2004).
Analysis of Adult Phenotype
We measured the following 15 standard continuous
morphological characters following methods and definitions
of Brown and Guttman (2002) and Emerson (1994): SVL,
head length, snout length, tympanum diameter, head width,
forearm length, femur length, tibia length, tarsus length, foot
length, hand length, eye–narial distance, internarial distance,
fang length, and fang height. To eliminate bias caused by
ontogenetic variation, each character (except SVL) was
scaled to the same size by adjusting shape according to
allometry (Thorpe 1983; Lleonart et al. 2000). Measure-
ments from 98 male and 62 female adult individuals of
Fanged Frogs (from a set of 161, including subadults; Fig. 1)
114 Herpetological Monographs 35, 2021

from throughout the Mindanao PAIC were adjusted for
allometric growth using the following equation: X
adj
¼log
(X)b(log SVL – log SVL
mean
), where X
adj
¼adjusted
value; X¼measured value; b¼unstandardized regression
coefficient for each population found by regressing each
mensural character on SVL; SVL ¼measured SVL; SVL
mean
¼overall average SVL of all samples. All downstream
analyses were performed on the adjusted values.
Before attempting statistical procedures, we performed
an F-test to test for heteroscedasticity for each character
across populations (separately for each sex) and, in cases
where characters violated the assumption of homogeneity of
variance, we performed Kruskal–Wallis rank sum tests to
evaluate whether samples originate from the same distribu-
tion.
We also transformed data to account for differences in
body size by performing separate linear regressions between
SVL and each of the remaining 14 variables. We then
substituted residuals of these regressions for the raw data for
those characters in all further univariate and multivariate
analyses. We did not transform the SVL data themselves but
did include this measure of body size in subsequent
univariate analyses. After ensuring that data conformed to
assumptions of normality by performing separate Shapiro–
Wilk tests on each variable in the data set (results not shown;
P0.05), we tested if the different populations display mean
differences in single morphometric characters with two-way
analyses of variance (ANOVAs) using sex (males, females) as
factors. We followed this up with a Tukey honestly significant
difference test to determine specifically which population
pair of character means differed after adjusting for multiple
comparisons. All morphological analyses were performed
and visualized in R v3.6.1 (R Core Team 2019). Specimens
and genetic material are deposited at the University of
Kansas, the Field Museum of Natural History, the Texas
Natural History Collection of the University of Texas at
Austin, the Cincinnati Museum of Natural History, and the
National Museum of the Philippines (institutional abbrevi-
ations follow Sabaj 2019).
We used principal components analysis (PCA) to find the
best low-dimensional representation of variation in the data
to determine whether morphological variation could form
the basis of detectable group structure. Eigenvalues .1
were retained according to Kaiser’s criterion (Kaiser 1960)
and the R package hypervolume (Blonder et al. 2014) was
used to construct hypervolumes using gaussian kernel
density estimation to estimate the probability density
function of the retained principal components (PCs). To
characterize clustering and distance in morphospace, and to
determine whether either past taxonomy or preliminary
results from 16S mitochondrial gene phylogeography could
be used to distinguish putative species, a discriminant
analysis of PCs was performed to find the linear combina-
tions of morphological variables that have the largest
between-group variance and the smallest within-group
variance. This approach relies on data transformation using
PCs analysis as a preliminary step before a subsequent
discriminant analysis, ensuring that variables included in the
latter step are uncorrelated and number fewer than the
sample size (Jombart et al. 2010).
Analysis of Acoustic Data
Calls were recorded by using a Nagra VI digital recorder
at a sampling rate of 44.1 kHz. We inspected vocalizations
as oscillograms and spectrograms that were generated using
the R package seewave (Sueur et al. 2008). We measured
call parameters including mean dominant frequency (max-
imum frequency using the analytical programs selection
spectrum function over the duration of the entire call),
mean call duration (time between onset of first pulse and
offset of last pulse in a call), and call rise (time between
onset of first pulse and onset of pulse of maximum
amplitude) and fall times (time between onset of pulse of
maximum amplitude and offset of last pulse) using Raven
Pro v1.5 (Center for Conservation Bioacoustics 2014), with
the Hanning window type and a discrete Fourier transform
window size of 256 points and 50% overlap with 44.1-Hz
sampling rate. We present ranges followed by mean 61SD
in parentheses.
Allocation of Mindanao Giant Fanged Frog Names
Given past differences in assignment of species’ taxonom-
ic epithets to giant Fanged Frogs of the Mindanao faunal
region (Inger 1954; Brown and Alcala 1970, 1977; Evans et
al. 2003; Siler et al. 2009), we endeavored to definitively
assign existing names to genetically and phenotypically
characterized units by incorporating both classes of data
deliberately collected from specimens from the type locality
of each species. We also examined and incorporated data
from the type specimens of each species, as a final specifying
measure, to independently confirm/refute our assignment of
available names to groups demonstrably representing
distinct evolutionary lineages (species).
RESULTS
Phylogenetic Analyses
Our RAxML maximum-likelihood analysis of 16S mtDNA
data generated a single point estimate topology of a log
likelihood of –logL 12,343.50 (Fig. 1). The preferred
topology suggests that L. magnus (sensu lato) is non-
monophyletic (Fig. 1); that is, the high-elevation Mt. Apo
population—considered by Evans et al. (2003) to likely
represent true L. magnus—is in fact more closely related to
L. diuatus than it is to the widespread L. cf. magnus from
low-elevation Mindanao and the remaining Mindanao faunal
region islands.
The 16S mtDNA maximum-likelihood tree containing
populations sampled from throughout the Mindanao PAIC
infers the presence of two subclades with strong bootstrap
support, with moderate levels of genetic divergence
between these two clades, and low levels of divergence
within each clade (Supplemental Figs. S1, S2, available
online). One strongly supported subclade corresponds to the
Mindanao-endemic high-elevation clade containing the type
locality of L. diuatus (green clade: high elevations [1000
m] from Mt. Hilong-hilong, NE Mindanao; Fig. 1), along
with closely related haplotype clades from Mt. Lumot (L.
diuatus 1, orange clade: Municipality of Gingoog, Misamis
Oriental, northern Mindanao), and Mt. Apo (L. diuatus 2,
red clade: Municipality of Toril, Davao City Province, SE
Mindanao), and L. ferneri (green clade: Municipality of
115
ABRAHAM ET AL.— TAXONOMIC RESOLUTION OF THE LIMNONECTES MAGNUS GROUP

Monkayo, Davao del Norte Province, south-central Mind-
anao).
The second, moderately supported subclade included
three weakly supported groups from across low elevations of
the Mindanao PAIC. One contained haplotype clade (L.
magnus 1, yellow clade) is limited to Bohol, whereas another
(L. magnus 2, purple clade) is distributed among the islands
of Samar, Leyte, and Dinagat. A third haplotype clade (L.
magnus 3, blue clade) is widely distributed throughout
Mindanao, Samar, Dinagat, Siargao, and Camiguin Sur.
Pairwise divergence for 16S within the lowland L. magnus
clade was as high as 3.4% (Supplemental Fig. S1), whereas
that within the high-elevation L. diuatus clade was 4% at
maximum. Divergence between these two clades ranged 5–
7.5% (Supplemental Fig. S1).
Bayesian and maximum-likelihood IQ-TREE analyses of
our complete multilocus concatenated data set (16S þthree
nuclear genes) both estimated two primary clades (Fig. 2).
Populations sampled from high-elevation sites (1000 m) on
Mindanao Island formed a clade, as did remaining samples
from lower-elevation sites throughout the Mindanao PAIC
(Fig. 2). The high-elevation clade (united by only moderate
support) contains type locality L. diuatus 1 (orange clade)
and L. diuatus 2 (red clade) and includes two moderately
supported clades of L. diuatus and L. ferneri. The Mindanao
PAIC widespread clade of mostly low-elevation L. magnus
contains two poorly supported subclades: Bohol, Samar,
Dinagat, Siargao, Camiguin Sur, and Mindanao and another
from Bohol, Samar, Leyte, and Dinagat.
Morphometric Characterization of Phenotype
After transformation (except SVL, which was not
transformed), we rejected the null hypothesis of equal
variances (homoscedasticity) for internarial distance (F¼
0.471, P¼0.043), and subsequently we implemented a
Kruskal–Wallis test, which identified marked interpopula-
tional variation (v
2
¼11.54, df ¼4, P.0.05). For all other
variables we implemented an ANOVA. Our Shapiro–Wilk
tests confirmed that our mensural characters satisfied the
assumption of normality (P.0.05; individual P-values not
shown). Our ANOVAs showed that there were differences
among populations for every character except femur length
(P¼0.928) and internarial distance (P¼0.07) in males, and
for fang length (P¼0.98) and fang height (P¼0.71) in
females. Our nonparametric tests were consistent with the
ANOVA results, except for internarial distance in males (P¼
0.48), but this does not affect our conclusions. The Tukey
test further revealed differences between males of true L.
diuatus (green) and L. diuatus 1 (orange) for numerous
characters (all except SVL, femur length, eye–narial
distance, and internarial distance), whereas comparisons
between the L. magnus (purple) and L. magnus (yellow)
populations yielded the few statistical differences (only foot
length differed; Table 1).
Among males, the first four PCs had eigenvalues .1and
accounted for 75.2% of the total variation. Among females,
the first five PCs had eigenvalues .1 and accounted for
81.2% of the total variation. These were retained for the
discriminant analysis, the results of which are as follows. In
males, the first PC accounted for 36.2% of the variation and
FIG. 2.—Bayesian maximum clade credibility tree, illustrating relationships among Mindanao Pleistocene aggregate island complex (PAIC) Fanged Frogs,
inferred from analysis of four concatenated loci (16S ribosomal ribonucleic acid [rRNA], carnitine palmitoyltransferase II [CPT-2], lactase [LCT], pro-
opiomelanocortin [POMC]). Nodal support: Bayesian posterior probabilities and bootstrap percentages from a separate maximum-likelihood analysis, which
inferred the same topology (see text for details). Clades color-coded as in Fig. 1.
116 Herpetological Monographs 35, 2021

TABLE 1.—Analysis of variance (ANOVA) and Tukey honestly significant difference (HSD) tests on 15 morphometric characters of male and female adult individuals. Asterisks (*) denote characters for
which we rejected the hypothesis of being drawn from a single distribution, on the basis of a¼0.05. Characters include (1) snout–vent length, (2) head length, (3) snout length, (4) tympanum diameter, (5)
head width, (6) forearm length, (7) femur length, (8) tibia length, (9) tarsus length (10), foot length, (11) hand length, (12) eye–narial distance, (13) internarial distance [Kruskal–Wallis P-value in brackets],
(14) odontoid length, (15) odontoid height.
123456789101112131415
Males
ANOVA 0.000*0.000*0.000*0.000*0.000*0.000*0.928 0.000*0.000*0.000*0.000*0.000*0.070 0.001*0.054*
[0.481]
Tukey HSD
L. diuatus (green)–L. diuatus 1 (orange) 0.995 0.000*0.000*0.003*0.000*0.000*0.915 0.000*0.000*0.000*0.000*0.991 0.558 0.014*0.046*
L. magnus 3 (blue)–L. diuatus (green) 0.000*0.111 0.000*0.409 0.994 0.000*0.503 0.000*0.000*0.000*0.111 0.000*0.998 0.972 0.695
L. magnus 3 (blue)–L. diuatus 1 (orange) 0.019*0.000*0.315 0.016*0.000*0.000*1.000 0.999 0.417 0.691 0.000*0.002*0.395 0.018*0.130
L. magnus 2 (purple)–L. diuatus (green) 0.849 0.051*0.000*0.000*0.905 0.979 0.949 0.000*0.000*0.000*0.051*0.000*0.665 0.824 0.999
L. magnus 2 (purple)–L. diuatus1 (orange) 0.871 0.001*0.399 0.682 0.001*0.000*0.989 0.719 0.032*0.368 0.001*0.002*0.916 0.002*0.046*
L. magnus 1 (yellow)–L. diuatus (green) 0.984 0.999 0.021*0.542 0.930 0.998 1.000 0.000*0.007*1.000 0.999 0.000*0.835 0.590 0.998
L. magnus 1 (yellow)–L. diuatus 1 (orange) 1.000 0.001*0.441 0.379 0.001*0.002*0.925 0.977 0.591 0.006*0.001*0.009*0.280 0.617 0.280
L. magnus 3 (blue)–L. magnus 2 (purple) 0.000*0.934 0.999 0.000*0.953 0.000*0.850 0.105 0.014*0.619 0.934 0.998 0.177 0.170 0.690
L. magnus 3 (blue)–L. magnus 1 (yellow) 0.012*0.859 0.994 0.943 0.822 0.047*0.840 0.984 0.999 0.005*0.859 0.950 0.868 0.719 0.997
L. magnus 2 (purple)–L. magnus 1 (yellow) 0.798 0.709 0.987 0.805 0.680 1.000 0.974 0.990 0.837 0.035*0.709 0.978 0.366 0.226 1.000
Females
ANOVA 0.000*0.000*0.000*0.000*0.014*0.000*0.000*0.000*0.000*0.000*0.000*0.000*0.005*0.982 0.710
Tukey HSD
L. diuatus (green)–L. diuatus 1 (orange) 0.845 0.000*0.460 0.608 0.231 0.013*0.000*0.000*0.000*0.000*0.000*0.254 0.168 1.000 0.920
L. magnus 3 (blue)–L. diuatus (green) 0.004*0.000*0.000*0.007*0.014*0.000*0.016*0.000*0.000*0.000*0.000*0.000*0.997 1.000 0.918
L. magnus 3 (blue)–L. diuatus 1 (orange) 0.000*0.998 0.122 0.000*0.998 0.018 0.005*0.950 0.999 0.019*0.998 0.000*0.116 1.000 0.999
L. magnus 2 (purple)–L. diuatus (green) 0.474 0.008*0.005*0.000*0.808 0.040*0.670 0.000*0.000*0.288 0.008*0.000*0.685 0.987 0.841
L. magnus 2 (purple)–L. diuatus1 (orange) 0.104 0.794 0.429 0.000*0.840 0.981 0.002*1.000 0.905 0.002*0.794 0.008*0.858 0.984 1.000
L. magnus 1 (yellow)–L. diuatus (green) 0.220 0.000*0.001*0.001*0.460 0.000*0.113 0.000*0.000*0.012*0.000*0.000*0.792 1.000 1.000
L. magnus 1 (yellow)–L. diuatus 1 (orange) 0.027*0.997 0.486 0.000*0.875 0.230 0.002*0.988 0.839 0.003*0.997 0.000*0.005*0.999 0.926
L. magnus 3 (blue)–L. magnus 2 (purple) 0.584 0.350 0.998 0.008*0.426 0.001 0.640 0.942 0.600 0.375 0.350 0.994 0.689 0.982 0.988
L. magnus 3 (blue)–L. magnus 1 (yellow) 0.263 0.828 0.788 0.708 0.242 0.528 0.915 0.998 0.666 0.669 0.828 0.958 0.215 1.000 0.891
L. magnus 2 (purple)–L. magnus 1 (yellow) 1.000 0.818 0.991 0.115 0.998 0.034*0.940 0.987 0.186 0.913 0.818 0.921 0.083 0.995 0.832
117
ABRAHAM ET AL.— TAXONOMIC RESOLUTION OF THE LIMNONECTES MAGNUS GROUP

possessed heavy loadings for snout length, tibia length, tarsus
length, and foot length, indicating that these characters
explained most of the variation along the first axis; this axis
did not form the basis of group separation for any a
posteriori recognized groups. The second component
accounted for 20.5% of the variation with heavy loadings
for head width and forearm length (Table 2). In females, the
first PC accounted for 36.7% of the variation with strong
loadings for tibia length, tarsus length, and internarial
distance, and the second PC accounted for 14.7% of the
variation, with highest loadings for tympanum diameter and
foot length (Table 2). These formed the basis of discrete
structure, separating the high-elevation Mindanao Island
Fanged Frog populations from those widely distributed
throughout the Mindanao PAIC (Fig. 3).
When we applied discriminant analysis procedures to our
a priori designated groups (DAPC), not surprisingly we
found discrete clustering of the high-elevation populations
(L. diuatus [green] þL. ferneri þL. diuatus 1 [orange])
versus the widespread L. magnus; our minimum-spanning
network, on the basis of the squared distances between
populations, demonstrated marked distance in morphospace
between these two primary groups (Fig. 3).
In both our phylogenetic estimates (Figs. 1, 2), we found
two primary clades; this dichotomy also formed the basis of
group structure in our PCA and these two groups were
successfully, and discretely, discriminated in morphospace
by our DAPC, particularly for adult males, which are larger
than females and possess the secondary sexual character of
prominent fangs on the lower jaw (Fig 3). Within these
groups, additional units could not be discretely identified
(Fig. 3). Tendencies toward minimal group separation was
observed within the high-elevation clade (with the caveat
that morphometric data from this lineage were not available
from Mt. Apo), but extensive overlap among the groups
(haplotype clades; Fig. 1) of low-elevation L. magnus was
evident (Fig. 3).
Allocation of Available Names
Limnonectes magnus (Stejneger 1910) versus ‘‘ L. cf.
magnus’’ sensu Evans et al. (2003).—In their phylogenetic
analysis of the genus Limnonectes, the assignment of the
name L. magnus to the high-elevation Mt. Apo population by
Evans et al. (2003) was based on Stejneger’s (1910:437)
report that the holotype (USNM 35231) specimen originated
‘‘between Todaya and camp, 4000 to 6000 ft elevation’’
(1219–1828 m asl) and the assumption that ‘‘camp’’ referred
to Lake Venado (an endorheic lake on Mt. Apo, situated at
7200 ft [2194 m] asl), which has been featured in numerous
expedition accounts (e.g., Hoogstral 1951; Inger 1954) and
where E.A. Mearns was known to have made collections.
Thus, the assumption that the holotype of L. magnus
originated between 1219 and 2194 m on Mt. Apo, combined
with the fact that the several immature specimens sequenced
by Evans et al. (2003) were collected (by RMB in 1991,
deposited at Cincinnati Museum of Natural History)
between 1200 and 1550 m on Mt. Apo, lent support to what
seemed at the time to be a reasonable assumption.
However, three newly available lines of evidence argue
against the assignment of Evans et al. (2003). First, the high-
elevation genotype (then assumed to be L. magnus, but
reassigned herein to L. diuatus, see below) was also collected
and genetically confirmed at lower elevations, in the vicinity
of Barangay Baracatan (Municipality of Toril; Davao City
Province) at 900 m. Second, the larger-bodied, widespread,
low-elevation form was also collected and genotyped by
Evans et al. (2003) from as high as 1275 m (Barangay
Baracatan). The fact that both forms were collected
sympatrically indicates a wider elevational range for the
high-elevation taxon than previously appreciated and intro-
duces the possibility that the assumption of Evans et al.
(2003) could be questioned. Third, and more important,
examination of the holotype (USNM 35231; male, 110 mm
SVL; no paratypes were designated by Stejneger 1910)
makes it clear that the name L. magnus applies to the larger-
bodied, widespread, low-elevation species, which Inger
TABLE 2.—Summary statistics and factor loadings for the first five components extracted in a principal components analysis of Mindanao Pleistocene
aggregate island complex Fanged Frog populations, analyzed separately by sex. See text for discussion of heavily loading individual characters (bolded for
emphasis).
Characters
Males Females
12 345 1 2 345
Snout–vent length 0.1121 0.2913 0.0954 0.489 0.2669 0.1498 0.1660 0.1230 0.4170 0.0266
Head length 0.263 0.3611 0.1472 0.3103 0.0728 0.3234 0.2779 0.0886 0.2877 0.1990
Snout length 0.3828 0.0012 0.1083 0.0213 0.2602 0.3002 0.2078 0.0434 0.0296 0.2654
Tympanum diameter 0.1818 0.3285 0.1634 0.1682 0.2948 0.1220 0.3505 0.0152 0.3774 0.3612
Head width 0.1681 0.3848 0.0746 0.119 0.4067 0.2586 0.2146 0.0231 0.3487 0.2386
Forearm length 0.1028 0.3893 0.1447 0.2911 0.2478 0.3273 0.1601 0.0091 0.2570 0.2027
Femur length 0.2715 0.1965 0.0835 0.3061 0.3325 0.2663 0.3952 0.1159 0.2283 0.0475
Tibia length 0.3609 0.186 0.131 0.0371 0.1584 0.3573 –0.2471 0.0786 0.1256 0.1436
Tarsus length 0.3554 0.2086 0.0751 0.1073 0.0177 0.3464 0.2408 0.0399 0.1674 0.1445
Foot length 0.3297 0.1963 0.0018 0.2538 0.2449 0.2642 0.4184 0.1445 0.1095 0.0955
Hand length 0.263 0.3611 0.1472 0.3103 0.0728 0.3234 0.2779 0.0886 0.2877 0.1990
Eye–narial distance 0.2834 0.1651 0.2381 0.0352 0.4691 0.3154 0.2417 0.0586 0.2060 0.0418
Internarial distance 0.1357 0.2249 0.1202 0.493 0.3343 0.0328 0.1302 0.1083 0.4146 0.7279
Fang length 0.1949 0.1014 0.6397 0.136 0.0556 0.0195 0.1686 0.6784 0.0564 0.0104
Fang height 0.2344 0.0584 0.6104 0.0828 0.0768 0.0038 0.1619 0.6700 0.0648 0.1911
Standard deviation 2.3307 1.7555 1.2847 1.0594 0.9235 2.3459 1.4838 1.3840 1.2338 1.0188
Eigenvalues 5.4324 3.0819 1.6504 1.1223 0.8528 5.5034 2.2016 1.9156 1.5222 1.0380
Proportion of variance 0.3622 0.2055 0.11 0.0748 0.0569 0.3669 0.1468 0.1277 0.1015 0.0692
Cumulative proportion 0.3622 0.5676 0.6776 0.7525 0.8093 0.3669 0.5137 0.6414 0.7428 0.8121
118 Herpetological Monographs 35, 2021

(1954:287) characterized as ‘‘frequently in excess of 100 mm,
and occasionally over 120 mm snout to vent.’’ We note that
this body size is far larger than the high-elevation form (L.
diuatus, see below) in which adult male body size varies
58.4–84.3 (Brown and Alcala 1977; Siler et al. 2009). The
holotype specimen (Fig. 4) is an adult male (sex confirmed
by gonadal inspection) with evident secondary sexual
characteristics typical of full-sized adult male L. magnus
(hypertrophied jaw adductor musculature, greatly enlarged
head, with jaw [in ventral aspect] laterally expanded). The
holotype’s boldly contrasting transverse tibial bars, pale
subarticular tubercles, pale ventral surfaces of finger discs,
and smooth dorsal skin are all in agreement with the
widespread, low-elevation species (Fig. 5) and stand in
contrast to the diffuse tibial markings, dark gray/black
subarticular tubercles, dark ventral surfaces of finger discs,
bright white ventrum (Figs. 2, 6), and irregularly shagreened
dorsal skin texture of the high-elevation species (Figs. 5, 6).
Stejneger (1910:437) and Inger (1954:277) both commented
on the widespread Mindanao population’s uniquely distinc-
tive color pattern, with posterior abdomen and ventral
surfaces of rear limbs densely spotted with dark brown
pigment. This conspicuous color pattern has been observed
by the authors at numerous localities on Mindanao, Bohol,
Samar, and Leyte; it is evident in the holotype as well (Fig.
4), although unpigmented ventral surfaces in L. magnus have
been documented (Fig. 5).
In summary, with newly acquired evidence from addi-
tional genetic data, plus definitive examination of the
holotype of L. magnus (USNM 35231), all available data
point to the same conclusion and we have no hesitation in
reversing the assignment of Evans et al. (2003) of the name
L. magnus (Stejneger 1910) to the low-elevation, widespread
species of Mindanao PAIC Fanged Frog (Fig. 1; Table 3).
Limnonectes diuatus (Brown and Alcala 1977).—In
their description of R. diuata, Brown and Alcala (1977)
recognized the high-elevation population from Mt. Hilong-
hilong (approximate altitude 1000þm, of the Diuata
Mountain Range, Municipality of Cabadbaran, Agusan del
Norte Province) as a new species. They diagnosed it from L.
magnus (numerous specimens of which were available at that
time; represented by large sample sizes from various islands
FIG. 3.—Discriminant and principal components analyses for (A) males and (B) females; dots ¼individuals; ellipses ¼groups identified by discriminant
analysis of principal components. Three-dimensional plots in (C) males and (D) females depict first three principal components (larger circles ¼specimens;
minute kernels ¼gaps or clusters identified by the hypervolume multivariate kernel density estimation). Color-coding as in Fig. 1.
119
ABRAHAM ET AL.— TAXONOMIC RESOLUTION OF THE LIMNONECTES MAGNUS GROUP

FIG. 4.—Adult male holotype (USNM 35231) of Limnonectes magnus from Mt. Apo (collected between Todaya and Camp), Mindanao Island. A color
version of this figure is available online.
FIG. 5.—Adult male specimen of Limnonectes magnus (KU 314438) in (A) dorsal, (B) ventral, and (C) right lateral head views; (D) plantar surface (ventral
aspect of left foot); (E) palmar surface (ventral aspect of left hand). A color version of this figure is available online.
120 Herpetological Monographs 35, 2021

of the Mindanao PAIC; Brown and Alcala 1977) by its
smaller body size (male SVL ¼37.4–57.7 mm; n¼3; female
¼62.5–63.1; n¼2[L. magnus, in contrast, was reported
90.6–108.5 mm SVL in males and 80.3–93.6 in females]),
darker, more uniform overall dorsal and lateral coloration,
dark brown throat and sternal region pigmentation (absent in
L. magnus), its more rugose skin texture, shorter first finger
(relative to second), its somewhat more dilated toe discs, and
shorter relative tibia length. With the advantage provided by
the current-day availability of extensive collections from the
Mindanao PAIC (Brown et al. 2013; Sanguila et al. 2016),
plus genetic data presented here, it is encouraging that the
majority of these qualitative characterizations is generally
confirmed (Figs. 2, 4, 7)—albeit possibly nondiagnostic in
the sense that they do not represent nonoverlapping ranges
of discrete variation. Still, genetic data presented here
indicate that all high-elevation Mindanao populations
collected on Mt. Hilong-hilong, Mt. Magdiwata, Mt.
Balatukan, Mt. Lumot, and Mt. Apo are closely related
(Figs. 1, 2) and correspond to the smaller-bodied, range-
limited, high-elevation form that exhibits geographically
structured genetic variation (mountain-specific haplotype
FIG. 6.—Adult male specimen of Limnonectes diuatus (KU 320090) in (A) dorsal, (B) ventral, and (C) right lateral head views; (D) plantar surface (ventral
aspect of left foot); (E) palmar surface (ventral aspect of left hand). A color version of this figure is available online.
TABLE 3.—Four data streams, assessed for the presence/absence of support for each haplotype clade (color-coded to match Fig. 1) summarized among
Mindanao Pleistocene aggregate island complex Fanged Frog populations of the Limnonectes magnus complex (¼L. magnus,L. diuatus, and L. ferneri). ‘‘Y’’
¼yes; ‘‘N’’ ¼no (see Diagnosis sections for character states).
Clade in mitochondrial tree Clade in nuclear tree Supported by morphometrics Diagnosed with traditional character states
Highland clade: L. diuatus
L. diuatus 1 (orange) Y N N N
L. diuatus 2 (red) Y Y Y Y
L. diuatus (green) Y Y Y Y
L. ferneri (green) N N N Y
Lowland clade: L. magnus
L. magnus 1 (yellow) Y N N N
L. magnus 2 (purple) Y Y N N
L. magnus 3 (blue) Y Y N N
121
ABRAHAM ET AL.— TAXONOMIC RESOLUTION OF THE LIMNONECTES MAGNUS GROUP

clades) in rapidly coalescing mtDNA (Fig. 1), but shows no
such strongly supported geographically based genetic
substructure in our multilocus phylogenetic estimate (Fig.
2). Having incorporated examination of the L. diuatus type
series, and a combined multivariate analysis of the greatly
expanded sampling for high-elevation Mindanao Fanged
Frogs, we take the absence of group/sample-based structure
in our continuous morphometric data (broad overlap in L.
diuatus and other high-elevation populations in PCA, despite
some separation in PC1 of our DAPC analysis, which is
somewhat limited by the absence of morphometric data from
adults of the Mt. Apo population), shallow genetic diver-
gences in mtDNA (Fig. 1), and the lack of mountain massif-
based genetic structure in nuclear DNA (Fig. 2) to
conservatively refer all Mindanao Island ‘‘ sky island’’
populations to a single species, L. diuatus (Brown and Alcala
1977).
Limnonectes ferneri Siler, McVay, Diesmos and
Brown 2009.—In their description of L. ferneri, Siler et
al. (2009) described the population of Mindanao Fanged
Frogs from the Simulaw River drainage, Mt. Pasian
(Municipality of Monkayo, Davao del Norte Province),
emphasizing that in contrast to the generally smaller L.
diuatus with traditional amphibian female-larger sexual size
dimorphism, L. ferneri possessed reversed sexual size
dimorphism, typical of larger-bodied Limnonectes (Inger
1954; Brown and Alcala 1977; Setiadi et al. 2011). Characters
apparently diagnostic for L. ferneri and distinguishing the
species from L. diuatus included its larger (male SVL 79.6–
84.3 mm) versus smaller (male SVL 37.4–58.4) body size,
less rugose skin texture, finger I longer than finger II (versus
fingers subequal), densely (versus sparsely) distributed
dermal asperities, snout round (versus acuminate), and
absence of dorsolateral folds/ridges (versus present). With
the consideration of larger sample sizes from multiple
localities (Fig. 1), and that extend the known range of L.
diuatus from the original diagnosis of Brown and Alcala
(1977), we view most of the character comparisons of Siler et
al. (2009) as no longer diagnostic. Aside from the problem of
interpreting subjective/categorical characterizations (dense
versus sparse; smooth versus rugose), we note—as have
many others—that many purportedly diagnostic traditional
taxonomic characters in anuran systematics can be demon-
strably biased by circumstances of preservation, interpopu-
lational variation, reproductive cycle at time of preservation,
and interobserver bias (Hayek et al. 2001). Together with the
genetic data presented here, indicating a very close
relationship between L. diuatus from the species’ type
locality and the L. ferneri type series, we have no hesitation
in placing L. ferneri Siler, McVay, Diesmos and Brown 2009
FIG. 7.—Adult male holotype (PNM 9506) of Limnonectes ferneri from Mt. Pasian, Municipality of Monkayo, Davao Del Norte Province, Mindanao
Island, Philippines (Brown and Alcala 1977). A color version of this figure is available online.
122 Herpetological Monographs 35, 2021

in synonymy with L. diuatus (Brown and Alcala 1977). It
should be noted that although Brown and Alcala (1977)
reported L. diuatus male body size to vary 37.4–58.4 mm,
Siler et al. (2009) were unable to confirm sexual maturity in
the type series beyond a single male (SVL 58.4 mm) and a
single female (62.3 mm). Excluding immature specimens
and combining size variation from both species’ type series,
we emphasize that L. diuatus does in fact exhibit reversed
sexual size dimorphism (males on average slightly larger;
male SVL 58.4–84.3 mm; females 62.3–69.3).
TAXONOMIC SUMMARY
Limnonectes magnus (Stejneger)
(Figs. 4, 5)
Rana magna: Stejneger 1910:437. Holotype male (USNM
35231) from ‘‘Mount Apo, Mindanao, between Todaya
and camp, 4000 to 6000 ft altitude’’ (¼Philippines,
Mindanao Island, Davao City del Sur Province, Munic-
ipality of Bansalan, Barangay Sibulan, Sitio Tudaya)
[examined].
Rana (Rana) magna Boulenger 1920:6 (in part, misidentifi-
cation).
Rana modesta magna Smith 1927:211 (in part, misidentifi-
cation).
Rana macrodon magna Stejneger: Inger 1954:287 (in part,
misidentification).
Rana magna magna Stejneger: Inger 1958:254 (correction,
reidentification).
Rana (Euphlyctis) magna Stejneger: Dubois 1981:239 (by
implication).
Euphlyctis magna (Stejneger): Poynton and Broadley
1985:124 (transferred to genus Euphlyctis Fitzinger by
implication).
Limnonectes (Limnonectes) magnus (Stejneger): Dubois
1987:63 ‘‘1986’’ (transferred to genus Limnonectes
Fitzinger by implication).
Limnonectes cf. magnus: Evans, Brown, McGuire, Supriat-
na, Andayani, Diesmos, Iskandar, Melnick, and Canna-
tella 2003:794; Setiadi, McGuire, Brown, Zubairi,
Iskandar, Andayani, Supriatna, and Evans 2011:221
(misidentification).
Identification.—Limnonectes magnus differs from all
other Philippine congeners by a combination of the following
characters: adult large bodied (males ¼59.4–164.4 mm SVL;
females ¼47.6–130.8); skin on dorsum smooth, slightly
rugose laterally with irregular dark markings (Fig. 2); white-
tipped asperities limited to sacral region or absent;
tympanum not partially concealed by supratympanic fold
(Fig. 5C); interdigital webbing of foot complete; subarticular
tubercles and ventral surfaces of toe discs pale cream to gray;
finger discs nonexpanded; discs of toes slightly expanded
(Fig. 5D,E); snout rounded in dorsal and lateral aspect;
supralabial region with two or three broad, diffuse, indistinct
dark blotches; dorsal coloration variable from light brown or
gray to olive brown or dark brown; inguinal region and
ventral surfaces of hindlimbs with densely spotted dark
pigmentation in 88% of specimens; ventral throat, sternal
region, and other body surfaces otherwise cream to pale
yellow. Male advertisement call amplitude-modulated (‘‘ keh-
keh-keh-keh. . .’’), with 10–16 rapid, loud, and invariant
notes.
Distribution and natural history.—Limnonectes mag-
nus has been reported from numerous low-elevation habitat
types, usually in the vicinity of water (ponds, lakes, seepages,
streams, rivers; see also comments by Inger 1954). The
species has been recorded most frequently below 1200 m,
but a few confirmed L. magnus specimens have been
collected as high as 1350 m. It exhibits a widespread
distribution, and has been documented throughout the
Mindanao PAIC, including on the islands of Mindanao,
Siargao, Camiguin Sur, Dinagat, Samar, Leyte, Bohol and,
Basilan and presumably, Biliran (Taylor 1920; Inger 1954;
Diesmos et al. 2015; Sanguila et al. 2016). The tadpole and
larval development of this species has not been described.
Advertisement call.—We include the following brief
description of the male advertisement call (Fig. 8) of L.
magnus on the basis of the recordings of two males
(specimens not collected) recorded by RMB at Barangay
Pasonanca, Municipality of Zamboanga City, western Mind-
anao Island (1130 m elevation, west side of Pasonanca
Natural Park, at an area known locally as ‘‘ Nancy’’) in the
evening ~1730 to 1900 h (ambient temperature of 21.58C).
To the best of our knowledge this constitutes the first
description of vocalizations of the species.
The call of L. magnus is a stereotyped, repetitive, rapidly
pulsed, amplitude-modulated pulse train, sounding to the
human ear like ‘‘keh-keh-keh-keh-keh-keh-keh. . .’’ and
lasting several seconds, followed by several minutes of
silence. Call duration 1.64–2.95 s (2.24 60.30, n¼47 calls
from two specimens; Fig. 8); rise time 80.1–91.4 (86.46 6
3.1) ms; fall time 1100–1681.9 (1391.79 6157.36) ms; notes
(pulses) per call 10–16 (13 61.22); note repetition rate 2.7–
3.11 (2.8 60.58). Spectral properties of L. magnus calls
were invariant across recordings available and the majority of
call energy was concentrated between 0.6 and 1.5 kHz. Our
two recording segments exhibited an invariant dominant
FIG. 8.—Comparative spectrogram (frequency [kHz] versus time [s]) and
corresponding oscillogram (relative amplitude [dB] versus time [s]) of the
advertisement vocalization of Limnonectes magnus. The calls of L. diuatus
(and its junior synonym, L. ferneri) have never been recorded. A color
version of this figure is available online.
123
ABRAHAM ET AL.— TAXONOMIC RESOLUTION OF THE LIMNONECTES MAGNUS GROUP

frequency of 1.4 kHz for one male and 1.2 kHz in the other;
rich harmonic structure was evident up to 3.5 kHz. Over a 4-
night survey at this locality, the two focal individuals
intermittently called for several hours, starting near sunset
(1800 h) and extending for 2–3 h after dark; calling activity
was initiated by one male, initially with short calls of two to
five notes; then the second male responded, resulting in
more intensely alternating call exchanges for 3–8 min,
followed by periods of silence of 30–75 min, until another
bout of calling began again (RMB, personal observation).
During vocalizations, males remained partially concealed
beneath boulders (2–4-m diameter) in the immediate vicinity
of waterfalls and loudly cascading water.
Limnonectes diuatus (Brown and Alcala)
(Figs. 2, 6, 7)
Rana diuata: Brown and Alcala 1977:669. Holotype male
(CAS 133500) from ‘‘Taguibo River, south side of Mt.
Hilong-hilong, altitude 1000þm, Diuata Mountains,
Cabadbaran Agusan del Norte Province, Mindanao
Island, Philippines’’ [examined].
Limnonectes ferneri Siler, McVay, Diesmos and Brown
2009:106. Holotype male (PNM 9506) from ‘‘Simulaw
River Drainage, 2.3 km N, 1.0 km E of Peak 1409, Mt.
Pasian (7858016.2600 N, 126817050.5200 E; datum ¼WGS-
84), Municipality of Monkayo, Davao Del Norte
Province, Mindanao Island, Philippines’’ [examined;
new synonymy].
Limnonectes (Limnonectes) diuatus (Brown and Alcala),
Dubois 1987:63 ‘‘1986’’ (transferred to genus Limno-
nectes Fitzinger by implication).
Limnonectes magnus (Stejneger) Evans, Brown, McGuire,
Supriatna, Andayani, Diesmos, Iskandar, Melnick, and
Cannatella 2003:794; Setiadi, McGuire, Brown, Zubairi,
Iskandar, Andayani, Supriatna, and Evans 2011:221
(misidentifications).
Identification.—Limnonectes diuatus differs from all
known congeners by a combination of the following
characters: medium bodied (SVL males ¼58.4–84.3 mm;
females ¼62.3–69.3); skin of dorsum smooth to shagreened,
laterally highly rugose, with two to four longitudinal rows of
large dermal tubercles (or tubercular ridges), each associated
with a black spot (Fig. 2), with or without spiculate texture
from aggregations of white-tipped asperities (Siler et al.
2009:their Fig. 4); tympanum usually fully exposed, or
partially concealed along dorsoposterior margin by less-
prominent, obtusely angled (posteroventrally) supratym-
panic fold (Fig. 6C); interdigital webbing of foot complete;
subarticular tubercles, toe discs, and ventral surfaces of feet
dark gray to black; finger discs slightly expanded; discs of
toes moderately expanded (Fig. 8D,E); snout acuminate to
round in dorsal view, angled posteroventrally in lateral
aspect (Fig. 6C); supralabial region with four to six distinct,
round, dark brown spots (Figs. 2, 5, 8); dorsal coloration dark
brown to nearly black brown; ventral surfaces of body bright
white to pale cream; when present, dark brown ventral
pigmentation concentrated on throat, sternal region, and in
some specimens, posterior distal surfaces of limbs (Fig. 2);
loreal region vertically flat, not concave, pigmented as
surrounding lateral head surfaces (medium brown); known
from high-elevation riparian habitats (above 900 m, usually
above 1200 m) only on Mindanao Island. Male advertise-
ment call unrecorded.
Distribution and natural history.—Limnonectes diua-
tus occurs in high-elevation riparian habitats (montane
streams and small, rapidly cascading, high-gradient rivers;
Brown and Alcala 1977; Siler et al. 2009; Diesmos et al. 2015;
Sanguila et al. 2016) on Mindanao Island, above 900 m
(usually 1200 m) including Mt. Apo, Mt. Pasian, Mt.
Hilong-hilong, Mt. Magdiwata, Mt. Balatucan, Mt. Lumot,
and most likely numerous additional montane sites of eastern
and possibly central Mindanao. A single unvouchered record
for Mt. Kitanglad (Bukidnon, Central Mindanao) exists
(Diesmos et al. 2015). The absence of recordings of the
vocalizations of this species should be taken as a challenge
for future fieldwork—both from sites where it occurs
exclusively (high elevations, 1400 m) and at lower, mid-
elevations (900–1200 m), where it may occur syntopically
with L. magnus. The tadpole and larval development of this
species has not been described.
DISCUSSION
Our re-evaluation of the phylogenetic relationships,
clarification of the taxonomy, and consideration of island
and elevational distributions of L. magnus and allied taxa
leads to the conclusion that only two valid giant Fanged Frog
species can demonstrably be said to exist on the Mindanao
PAIC (Stejneger 1910; Taylor 1920; Inger 1954; Brown and
Alcala 1977). Rather than resulting in the previously
anticipated increase in species numbers, this exercise argues
for the placement of L. ferneri (Siler et al. 2009) in synonymy
with R. diuata Brown and Alcala 1977 (¼Limnonectes
diuatus) and reverses the assignment of Evans et al. (2003)
of available names (Brown et al. 2013; Diesmos et al. 2015;
Sanguila et al. 2016). Moreover, genetic identification of all
insular populations (including name-bearing type specimens
and expanded genetic data from relevant type localities) and
robust statistical characterizations of phenotypic data failed
to identify unambiguous support for additional, unrecog-
nized lineages or putative new species. Our conservative
interpretation at this point stems from the lack of agreement
among available data streams (e.g., mtDNA phylogeny,
multilocus phylogeny, morphometric analyses, traditional
characters) and the absence of comparable data from all
relevant populations (recordings of advertisement calls are
unavailable for L. diuatus or from allopatric populations
[Bohol vs. Mindanao] of L. magnus). Consideration of the
Bohol Island population of L. magnus illustrates these
points. With only a phylogeny estimated from single-locus
mitochondrial sequences (Fig. 1) and a morphometric
analysis (Fig. 3), one might be tempted to suggest that the
allopatric Bohol population could be an example of an
unrecognized, morphologically cryptic, new species—em-
bodying a popularly potentially widespread predicted
phenomenon in Southeast Asian amphibian systematics
and biodiversity science (Bickford et al. 2007; Inger et al.
2009; Matsui et al. 2010)—and which it may very well prove
to be. However, analyses from individual and combined
nuclear genes (not shown) did not result in strong support
for Bohol populations as a distinctive, first-diverging lineage,
as observed in the mtDNA gene tree (Fig. 1). Further, our
multilocus Bayesian and likelihood estimates differed
124 Herpetological Monographs 35, 2021

substantially in support at several nodes relevant to Bohol
samples, which were not even inferred to be monophyletic
(Fig. 2). Finally, additional lines of evidence germane to the
question of the Bohol population, such as ecological
information, bioacoustics, or data from larval phenotypes,
are unavailable. Although we acknowledge that a markedly
divergent or structurally distinctive mate-recognition signal
(the male anuran advertisement call; Wells 2007) would
cause reconsideration of our interpretation (Herr et al.
2021), at present we hold in abeyance any additional
taxonomic changes until a time when changes to synonymy
are unavoidable and bolstered with appropriate evidence.
Until such gaps in our data and sampling are ameliorated, we
would consider it speculative and even irresponsible to assert
strong conclusions regarding possible existence of additional
species. As such, we refrain from proposing new names or
other liberal taxonomic changes, which might cascade into
downstream error in synonymy (Frost 2020), create addi-
tional misunderstanding for biodiversity information prod-
ucts (AmphibiaWeb 2020) and national Red List summaries
(Gonzalez et al. 2018), or result in extraneous, wasteful
expenditure of conservation resources (Diesmos and Brown
2011; Leviton et al. 2018). The emergence of conspicuous
case studies involving sequential reconsiderations of seem-
ingly straightforward anuran taxonomic revisions, using
increasingly sophisticated analytical approaches (e.g., multi-
species coalescent-based methods and empirical character-
izations of gene flow) and the power of statistical species
delimitation procedures coupled with technology allowing
locus sampling from across the genome (Hutter et al. 2019)
have made clear the weaknesses, pitfalls, and potential for
error associated with making strong conclusions on the basis
of single-locus studies, and even those on the basis of a
handful of loci (Brown and Guttman 2002; Brown and Siler
2014; Chan et al. 2020).
The emergent interpretation of a widespread low-
elevation, larger-bodied generalist species (L. magnus)
distributed on many Mindanao faunal region islands versus
a high-elevation montane species (L. diuatus) restricted to
the higher reaches of isolated ‘‘sky island’’ massifs of
Mindanao likely would have become apparent earlier if
high-elevation herpetological survey work on Mindanao had
not been so infrequent over the last 3 decades (Sanguila et
al. 2016). This lack of modern, high-quality biodiversity
surveys has resulted in a general lack of genetic material and
specimen-associated data (ecology, bioacoustics, larval biol-
ogy, etc.), all of which have the potential to contribute to the
pluralistic, integrative species delimitation standards of today
(Fujita et al. 2012; Carstens et al. 2013). Another factor that
likely delayed the resolution of Mindanao Fanged Frog
taxonomy may have been the small number of sexually
mature specimens in the original type series (Stejneger 2010;
Brown and Alcala 1977; Siler et al. 2009). In the case of L.
diuatus, inclusion of immature specimens in the original type
series also mistakenly gave the impression of females-larger
sexual size dimorphism and small male body size in this
species (Brown and Alcala 1977; Siler et al. 2009).
The collection of the original holotype specimen of L.
magnus at the very upper limit of its elevational distribution
(Stejneger 1910) and collection of the type series of L.
diuatus near the lower extent of its range (Brown and Alcala
1977; precisely at the point where we now conclude they are
narrowly sympatric and syntopic) further contributed to
biologists’ confusion, as did the inadvertent switching of
names for ‘‘L. magnus’’ and ‘‘L. cf. magnus’’ on the tips of
the first-available phylogenetic estimate (Evans et al. 2003).
With our redefinition of each species, clarification of their
status with respect to one another via diagnoses presented
here, and characterization of their geographic ranges and
elevational limits (confirmed with genetic data), we antici-
pate that field biologists will have the necessary tools to
properly identify, further study, and assess the conservation
status of these still poorly known taxa.
In addition to full descriptions of the advertisement calls
of both species, proper descriptions of tadpoles and larval
development of both taxa are long overdue. With careful
study of their microhabitats and focus on whether they
partition resources in areas of elevational sympatry, it should
be possible to characterize their general natural history and
true extent of occurrence. It is clear that this study would not
have been possible without the existence of (and our access
to) the relevant name-bearing type specimens, which
provided the crucial clues and other bits of evidence needed
to make sense of the historical uncertainty surrounding L.
magnus, L. diuatus, L. ferneri, and other hypothesized
species of Mindanao Fanged Frogs (Brown and Diesmos
2002; Evans et al. 2003), all of which underscores the
importance of properly vouchered specimens and specimen-
associated data in freely available natural history museums
and biodiversity repositories (McLean et al. 2016; Miralles et
al. 2020). Given the half-century of confusion that has
resulted from indiscriminate acceptance of assumptions
from earlier taxonomy and the practice of relying on expert
opinions for policy making (IUCN 2020), the case of L.
magnus provides an important lesson regarding the pitfalls of
misinterpretation that may develop when actual biodiversity
surveys have not been conducted. In such cases, the data
needed to inform conservation status assessments are
unavailable (McLean et al. 2016; Miralles et al. 2020), and
yet this lack of data is often itself incorrectly interpreted
when implementing legal policy (Brown and Diesmos 2002;
Hilton-Taylor 2000; Leviton et al. 2018; Gonzalez et al. 2018;
Betts et al. 2020; Brown et al. 2020).
The case of Mindanao Fanged Frog classification is
compelling for several reasons. Limnonectes magnus is one
of the most widespread, common, and abundant, supposedly
well-studied species in the southern portions of the
archipelago (Taylor 1920; Inger 1954; Alcala and Brown
1998; Sanguila et al. 2016). Its distribution is well
characterized (Brown and Alcala 1970; Diesmos et al.
2015) and challenges to its conservation have been
reasonably well discussed (Diesmos and Brown 2011; Brown
et al. 2012; Gonzalez et al. 2018; IUCN 2020). Naturally, we
might ask why has it taken so long for biologists to connect
the dots from scientific names to name-bearing type
specimens (the Linnaen shortfall; Lomolino et al. 2010)
and, eventually, to actual biological populations? Our
experience suggests that current trends toward increasingly
restrictive research permit systems and sociopolitical obsta-
cles to biodiversity research is to blame—and that the latter
represents a worrisome trend. Even if recent wholesale
reclassification of Philippine amphibians to increasingly
higher threatened conservation status categories justifies
bureaucratic obstacles to research (Gonzalez et al. 2018), we
125
ABRAHAM ET AL.— TAXONOMIC RESOLUTION OF THE LIMNONECTES MAGNUS GROUP

argue that limiting biologists’ access to species occurrence
data (the Wallacean shortfall) will always be counterproduc-
tive. On the basis of first principles of biodiversity science
(taxonomy, species occurrence data), an understanding of
species boundaries and their real-world geographic distri-
butions are destined to remain the crucial gold standard for
formulation and implementation of effective conservation
efforts (Diesmos and Brown 2011; Brown et al. 2014;
Diesmos et al. 2015; Leviton et al. 2018).
Acknowledgments.—Support for our work in the Philippines has been
generously provided by the US National Science Foundation (NSF EF
0334928, Division of Environmental Biology [DEB] 0073199, 0344430,
0743491, and 0804115); most recent studies focusing on Philippine
Limnonectes were funded by DEB 1654388 to RMB. We thank J. Vindum,
A. Leviton, R. Drewes, D. Blackburn, R. Sison, and A.C. Diesmos (PNM);
R. Inger, A. Resetar, and H. Voris (FMNH); K. de Queiroz and R. Crombie
(USNM); T. LaDuc and D. Cannatella (TNHC); and J. Hanken, J. Losos,
and J. Rosado (MCZ) for access to specimens and provision of workspace
during visits to collections where Philippine Limnonectes specimens are
housed. Special thanks to J.L. Welch (USNM), who photographed and
provided digital images of the holotype of L. magnus. Phylogenetic analyses
were conducted in part on Cornell’s Computational Biology Services Unit
BioHPC cluster and University of Kansas (KU)’s Center for Research
Computing. We especially appreciate the logistical support of the Philippine
Biodiversity Monitoring Bureau (BMB; formerly Parks and Wildlife Bureau,
PAWB) of the Department of Environment and Natural Resources (DENR)
and we thank authorities at DENR for their facilitation of research
agreements, collecting permits, and export permits necessary for this and
related studies. Specimens were collected by RMB, KU students, and
colleagues under the aegis of three formal Memoranda of Agreement
(MOA) between KU and the BMB (formerly PAWB) of the Philippine
central government (MOAs, 2004, 2009, 2015, endorsed by Chancellor of
KU and the Secretary of the DENR, Quezon City, Manila) and a formal
Specimen Repository Agreement at the KU Biodiversity Institute (KU-BI)
stipulating ownership by the National Museum of the Philippines. With local
municipal permissions obtained in the form of Prior Informed Consent
certificates (obtained from all collection sites), specimens were subsequently
collected under BMB Gratuitous Permits to Collect Biological Specimens
(185, 185-renewal, 201, 201-renewal, 212, 212-renewal, 221, 221-renewal,
228, 228-renewal, 228-Amendment, 228-3rd renewal, 228-4th renewal, 246,
246-renewal, 258, 258-renewal, 258-Amendment, 292, 292-renewal and
exported under the auspices of DENR Regional Office(s) Wildlife
Certification Export permit(s), with coordinated institutional permits
(APHIS, CITES, COSE F&W 3-177s) and Designated Port Exemptions
archived by the KU-BI’s administrative Office of the Director. Authoriza-
tions for the handling of live animals were provided to RMB by KU’s
Institutional Animal Care and Use Committee (IACUC AUS no. 185-05,
2004–2019).
We reserve special thanks for our collaborators in fieldwork: J. and B.
Fernandez, A.C. Diesmos, N. Antoque, J. Cantil, and V. Yngente; and we
thank the Zamboanga City Water District and provincial, municipal, and
local Pasonanca protected area officials who graciously provided access to
Pasonanca Natural Park for this and related studies. Finally, thanks are due
to P. De Mello for helping with formatting the base map used in Fig. 1 and
we thank Chan Kin Onn for constructive critique of an earlier draft of the
manuscript.
SUPPLEMENTAL MATERIAL
Supplemental material associated with this article can be
found online at https://doi.org/10.1655/HERPMONO
GRAPHS-D-20-00010.F1.
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128 Herpetological Monographs 35, 2021

APPENDIX I Taxa, Museum Repository Catalog Numbers, Localities, and GenBank Numbers for All Samples Included in this Study
Species Field no. Catalog no. Island Locality Elevation (m)
GenBank accession numbers
16S LCT
a
CPT2 POMC
Limnonectes diautus
(L. ferneri type)
JWF 94091 CMNH 5572 Mindanao Mt. Pasian, Simulaw River drainage,
Municipality of Monkayo, Davao del
Norte Province
MN759154
Limnonectes diautus
(L. ferneri type)
JWF 94093 PNM 9506
(Holotype)
Mindanao Mt. Pasian, Simulaw River drainage,
Municipality of Monkayo, Davao del
Norte Province
MN759153 MT631750
Limnonectes diautus
(L. ferneri type)
JWF 94094 CMNH 5573 Mindanao Mt. Pasian, Simulaw River drainage,
Municipality of Monkayo, Davao del
Norte Province
MN759155
Limnonectes diautus RMB 16161 KU 333370 Mindanao Mt. Hilong-hilong, May-Impit,
Municipality of Remedios T.
Romualdez, Agusan del Norte Province
1150 MN759175 MZ577259 MT631729 MT631754
Limnonectes diautus RMB 16164 KU 333373 Mindanao Mt. Hilong-hilong, May-Impit,
Municipality of Remedios T.
Romualdez, Agusan del Norte Province
1150 MN759145
Limnonectes diautus RMB 16224 KU 333374 Mindanao Mt. Hilong-hilong, May-Impit,
Municipality of Remedios T.
Romualdez, Agusan del Norte Province
1150 MN759176
Limnonectes diautus RMB 16225 KU 333375 Mindanao Mt. Hilong-hilong, May-Impit,
Municipality of Remedios T.
Romualdez, Agusan del Norte Province
1150 MN759144
Limnonectes diautus RMB 16232 KU 333381 Mindanao Mt. Hilong-hilong, May-Impit,
Municipality of Remedios T.
Romualdez, Agusan del Norte Province
1150 MN759178 MZ577257 MT631728
Limnonectes diautus RMB 16235 KU 333384 Mindanao Mt. Hilong-hilong, May-Impit,
Municipality of Remedios T.
Romualdez, Agusan del Norte Province
1150 MN759179 MZ577263 MT631725 MT631752
Limnonectes diautus RMB 16236 KU 333385 Mindanao Mt. Hilong-hilong, May-Impit,
Municipality of Remedios T.
Romualdez, Agusan del Norte Province,
Mindanao Island.
1150 MN759180
Limnonectes diautus RMB 16237 KU 333386 Mindanao Mt. Hilong-hilong, May-Impit,
Municipality of Remedios T.
Romualdez, Agusan del Norte Province
1150 MN759181
Limnonectes diautus RMB 16238 KU 333387 Mindanao Mt. Hilong-hilong, May-Impit,
Municipality of Remedios T.
Romualdez, Agusan del Norte Province
1150 MN759182
Limnonectes diautus RMB 16239 KU 333388 Mindanao Mt. Hilong-hilong, May-Impit,
Municipality of Remedios T.
Romualdez, Agusan del Norte Province
1150 MN759183
Limnonectes diautus RMB 16250 KU 333389 Mindanao Mt. Hilong-hilong, May-Impit,
Municipality of Remedios T.
Romualdez, Agusan del Norte Province
1150 MN759184
Limnonectes diautus RMB 16278 KU 333393 Mindanao Mt. Hilong-hilong, May-Impit,
Municipality of Remedios T.
Romualdez, Agusan del Norte Province
990 MN759186
Limnonectes diautus ACD 4274 KU 320079 Mindanao Mt. Balatukan Natural Park, Sitio San
Isidro, Boy Scout Camp, Barangay
Lumotan, Municipality of Gingoog,
Misamis Oriental Province
1450 MN759095 MZ577264 MT631732 MT631751
129
ABRAHAM ET AL.— TAXONOMIC RESOLUTION OF THE LIMNONECTES MAGNUS GROUP

APPENDIX I Continued.
Species Field no. Catalog no. Island Locality Elevation (m)
GenBank accession numbers
16S LCT
a
CPT2 POMC
Limnonectes diautus 1 ACD 4276 KU 320081 Mindanao Mt. Balatukan Natural Park, Sitio San
Isidro, Boy Scout Camp, Barangay
Lumotan, Municipality of Gingoog,
Misamis Oriental Province
1450 MN759096 MT631753
Limnonectes diautus 1 ACD 4316 KU 320085 Mindanao Mt. Balatukan Natural Park, Sitio San
Isidro, Boy Scout Camp, Barangay
Lumotan, Municipality of Gingoog,
Misamis Oriental Province
1450 MN759097 MZ577253 MT631739 MT631755
Limnonectes diautus 1 ACD 4324 KU 320090 Mindanao Mt. Balatukan Natural Park, Sitio San
Isidro, Boy Scout Camp, Municipality
of Gingoog, Misamis Oriental Province
1450 MN759098
Limnonectes diautus 1 RMB 16582 KU 333428 Mindanao Mt. Lumot, Barangay Civoleg,
Municipality of Gingoog, Misamis
Oriental Province
1236 MN759192 MZ577261 MT631733 MT631749
Limnonectes diautus 1 RMB 16627 KU 333438 Mindanao Mt. Lumot, Barangay Civoleg,
Municipality of Gingoog, Misamis
Oriental Province
1236 MN759194
Limnonectes diautus 2 PNM-CMNH H1197 NA Mindanao Mt. Talomo; Mt. Apo Natural Park, Sitio
San Roque, Barangay Baracatan,
Municipality of Toril, Davao Province
1530–1776 MN759156 MZ577251 MT631727 MT631757
Limnonectes diautus 2 PNM-CMNH H1198 NA Mindanao Mt. Talomo; Mt. Apo Natural Park, Sitio
San Roque, Barangay Baracatan,
Municipality of Toril, Davao Province
1530–1775 MN759157
Limnonectes diautus 2 PNM-CMNH H1199 NA Mindanao Mt. Talomo; Mt. Apo Natural Park, Sitio
San Roque, Barangay Baracatan,
Municipality of Toril, Davao Province
1530–1770 MN759158
Limnonectes diautus 2 PNM-CMNH H1200 NA Mindanao Mt. Talomo; Mt. Apo Natural Park, Sitio
San Roque, Barangay Baracatan,
Municipality of Toril, Davao Province
1530–1774 MN759159
Limnonectes diautus 2 PNM-CMNH H1205 NA Mindanao Mt. Talomo; Mt. Apo Natural Park, Sitio
San Roque, Barangay Baracatan,
Municipality of Toril, Davao Province
1530–1771 MN759160
Limnonectes diautus 2 PNM-CMNH H1206 NA Mindanao Mt. Talomo; Mt. Apo Natural Park, Sitio
San Roque, Barangay Baracatan,
Municipality of Toril, Davao Province
1530–1778 MN759164 MZ577258 MT631737 MT631758
Limnonectes diautus 2 PNM-CMNH H1244 NA Mindanao Mt. Talomo; Mt. Apo Natural Park, Sitio
San Roque, Barangay Baracatan,
Municipality of Toril, Davao Province
1530–1772 MN759161 MZ577248 MT631741 MT631756
Limnonectes diautus 2 PNM-CMNH H1246 NA Mindanao Mt. Talomo; Mt. Apo Natural Park, Sitio
San Roque, Barangay Baracatan,
Municipality of Toril, Davao Province
1530–1773 MN759162
Limnonectes diautus 2 PNM-CMNH H1247 NA Mindanao Mt. Talomo; Mt. Apo Natural Park, Sitio
San Roque, Barangay Baracatan,
Municipality of Toril, Davao Province
1530–1777 MN759163
Limnonectes magnus 1 CDS 4668 KU 323586 Bohol Raja Sikatuna Natural Park, Magsaysay
Park, Barangay Riverside, Municipality
of Bilar, Bohol Province
250 MN759130
Limnonectes magnus 1 CDS 4675 KU 323589 Bohol Raja Sikatuna Natural Park, Magsaysay
Park, Barangay Riverside, Municipality
of Bilar, Bohol Province
250 MN759131
130 Herpetological Monographs 35, 2021

APPENDIX I Continued.
Species Field no. Catalog no. Island Locality Elevation (m)
GenBank accession numbers
16S LCT
a
CPT2 POMC
Limnonectes magnus 1 CDS 4678 KU 323591 Bohol Raja Sikatuna Natural Park, Magsaysay
Park, Barangay Riverside, Municipality
of Bilar, Bohol Province
250 MN759132
Limnonectes magnus 1 CDS 4468 KU 323612 Bohol Raja Sikatuna Natural Park, Magsaysay
Park, Barangay Riverside, Municipality
of Bilar, Bohol Province
250 MN759129 MZ577255 MT631740 MT631745
Limnonectes magnus 1 CDS 4778 KU 323615 Bohol Raja Sikatuna Natural Park, Barangay
Danicop, Municipality of Sierra
Bullones, Bohol Province
250 MN759133
Limnonectes magnus 1 CDS 4821 KU 323619 Bohol Raja Sikatuna Natural Park, Barangay
Danicop, Municipality of Sierra
Bullones, Bohol Province
250 MN759134 MZ577252 MT631734 MT631760
Limnonectes magnus 1 CDS 4856 KU 323622 Bohol Raja Sikatuna Natural Park, Barangay
Danicop, Municipality of Sierra
Bullones, Bohol Province
250 MN759135
Limnonectes magnus 1 CDS 4867 KU 323627 Bohol Raja Sikatuna Natural Park, Barangay
Danicop, Municipality of Sierra
Bullones, Bohol Province
250 MN759136
Limnonectes magnus 1 CDS 4989 KU 323634 Bohol Raja Sikatuna Natural Park, Barangay
Danicop, Municipality of Sierra
Bullones, Bohol Province
250 MN759137 MZ577262 MT631726 MT631744
Limnonectes magnus 1 RMB 2887 KU 327507 Bohol Raja Sikatuna Natural Park, Barangay
Danicop, Bohol Province
390 MN759219
Limnonectes magnus 2 CDS 1804 KU 306022 Samar Barangay Poblacion, Municipality of San
Jose de Buan, Northern Samar Province
MN759107
Limnonectes magnus 2 CDS 1826 KU 306024 Samar Taft Forest, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759108
Limnonectes magnus 2 CDS 1827 KU 306025 Samar Taft Forest, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759109
Limnonectes magnus 2 CDS 1828 KU 306026 Samar Taft Forest, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759110
Limnonectes magnus 2 CDS 1839 KU 306028 Samar Taft Forest, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759111
Limnonectes magnus 2 CDS 1840 KU 306029 Samar Taft Forest, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759112
Limnonectes magnus 2 CWL 149 KU 306039 Samar Taft Forest, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759143
Limnonectes magnus 2 CWL 161 KU 306041 Samar Catbalogan City, Samar Province MN759246
Limnonectes magnus 2 CWL 162 KU 306042 Samar Catbalogan City, Samar Province MN759247
Limnonectes magnus 2 CWL 163 KU 306043 Samar Catbalogan City, Samar Province MN759248
Limnonectes magnus 2 CWL 164 KU 306044 Samar Catbalogan City, Samar Province MN759249
Limnonectes magnus 2 CWL 165 KU 306045 Samar Catbalogan City, Samar Province MN759146
Limnonectes magnus 2 CDS 1929 KU 306063 Dinagat Barangay San Juan, Municipality of
Loreto, Dinagat Province
MN759116
Limnonectes magnus 2 CDS 1934 KU 306068 Dinagat Barangay San Juan, Municipality of
Loreto, Dinagat Province
MN759118
131
ABRAHAM ET AL.— TAXONOMIC RESOLUTION OF THE LIMNONECTES MAGNUS GROUP

APPENDIX I Continued.
Species Field no. Catalog no. Island Locality Elevation (m)
GenBank accession numbers
16S LCT
a
CPT2 POMC
Limnonectes magnus 2 RMB 8548 KU 310190 Samar Barangay San Rafael, Municipality of Taft,
Eastern Samar Province
MN759233
Limnonectes magnus 2 RMB 8640 KU 310212 Samar Barangay San Rafael, Municipality of Taft,
Eastern Samar Province
MN759234
Limnonectes magnus 2 CDS 2805 KU 310587 Samar Barangay San Rafael, Municipality of Taft,
Eastern Samar Province
MN759121
Limnonectes magnus 2 CDS 2833 KU 310591 Samar Barangay San Rafael, Municipality of Taft,
Eastern Samar Province
MN759122
Limnonectes magnus 2 CDS 3078 KU 310604 Samar Barangay San Rafael, Municipality of Taft,
Eastern Samar Province
MN759123
Limnonectes magnus 2 CDS 3106 KU 310615 Samar Barangay San Rafael, Municipality of Taft,
Eastern Samar Province
MN759124
Limnonectes magnus 2 CDS 3216 KU 310969 Leyte Pilim, San Vicente, Municipality of
Baybay, Leyte Province
MN759125
Limnonectes magnus 2 CDS 3301 KU 310972 Leyte Pilim, San Vicente, Municipality of
Baybay, Leyte Province
MN759126
Limnonectes magnus 2 CDS 3304 KU 310975 Leyte Pilim, San Vicente, Municipality of
Baybay, Leyte Province
MN759127
Limnonectes magnus 2 CDS 3395 KU 310979 Leyte Pilim, San Vicente, Municipality of
Baybay, Leyte Province
MN759128
Limnonectes magnus 2 RMB 8947 KU 326360 Leyte Visayas State University Campus,
Municipality of Baybay, Leyte Province
MN759236
Limnonectes magnus 2 RMB 8953 KU 326361 Leyte Visayas State University Campus,
Municipality of Baybay, Leyte Province
MN759237
Limnonectes magnus 2 CDS 6992 KU 337806 Samar Mt. Huraw, Barangay Uno, Municipality
of San Jose de Buan, Northern Samar
Province
MN759139 MZ577260 MT631738 MT631743
Limnonectes magnus 2 CDS 7071 KU 337809 Samar Mt. Huraw, Barangay Uno, Municipality
of San Jose de Buan, Northern Samar
Province
MN759140
Limnonectes magnus 2 CDS 7072 KU 337810 Samar Mt. Huraw, Barangay Uno, Municipality
of San Jose de Buan, Northern Samar
Province
MN759141
Limnonectes magnus 2 CDS 7174 KU 337811 Samar Mt. Huraw, Barangay Uno, Municipality
of San Jose de Buan, Northern Samar
Province
MN759142
Limnonectes magnus 2 RMB 18467 KU 337814 Samar Kadakan River, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759204
Limnonectes magnus 2 RMB 18471 KU 337818 Samar Kadakan River, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759205
Limnonectes magnus 2 RMB 18475 KU 337822 Samar Kadakan River, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759206
Limnonectes magnus 2 RMB 18478 KU 337825 Samar Kadakan River, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759207
Limnonectes magnus 2 RMB 18482 KU 337829 Samar Kadakan River, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759208
132 Herpetological Monographs 35, 2021

APPENDIX I Continued.
Species Field no. Catalog no. Island Locality Elevation (m)
GenBank accession numbers
16S LCT
a
CPT2 POMC
Limnonectes magnus 2 RMB 18696 KU 337833 Samar Kadakan River, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759209
Limnonectes magnus 2 RMB 18744 KU 337837 Samar Kadakan River, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759210 MT631736 MT631759
Limnonectes magnus 2 RMB 19080 KU 337852 Samar DENR House, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759212
Limnonectes magnus 2 RMB 19101 KU 338896 Samar Barangay San Rafael, Municipality of Taft,
Eastern Samar Province
MN759213
Limnonectes magnus 2 CDS 6439 KU 340593 Samar Kadakan River, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759138 MZ577254 MT631748
Limnonectes magnus 3 ACD 7076 Deposited at PNM Siargao Barangay del Carmen, Surigao del Norte
Province
MN759106
Limnonectes magnus 3 CDS 2005 KU 306004 Dinagat Barangay Esperanza, Municipality of
Loreto, Dinagat Province
MN759120
Limnonectes magnus 3 CDS 1841 KU 306030 Samar Taft Forest, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759113
Limnonectes magnus 3 CDS 1844 KU 306033 Samar Taft Forest, Barangay San Rafael,
Municipality of Taft, Eastern Samar
Province
MN759114
Limnonectes magnus 3 CDS 1928 KU 306062 Dinagat Barangay San Juan, Municipality of
Loreto, Dinagat Province
MN759115
Limnonectes magnus 3 CDS 1931 KU 306065 Dinagat Barangay San Juan, Municipality of
Loreto, Dinagat Province
MN759117
Limnonectes magnus 3 CDS 1979 KU 306072 Dinagat Barangay Esperanza, Municipality of
Loreto
MN759119
Limnonectes magnus 3 CWL 252 KU 306076 Dinagat Barangay San Juan, Municipality of
Loreto, Dinagat Province
MN759147
Limnonectes magnus 3 CWL 253 KU 306077 Dinagat Barangay San Juan, Municipality of
Loreto, Dinagat Province
MN759148
Limnonectes magnus 3 CWL 257 KU 306081 Dinagat Barangay San Juan, Municipality of
Loreto, Dinagat Province
MN759149
Limnonectes magnus 3 CWL 299 KU 306082 Dinagat Barangay Esperanza, Municipality of
Loreto, Dinagat Province
MN759150 MZ577249 MT631730 MT631747
Limnonectes magnus 3 CWL 300 KU 306083 Dinagat Barangay Esperanza, Municipality of
Loreto, Dinagat Province
MN759152
Limnonectes magnus 3 CWL 324 KU 306084 Dinagat Barangay Esperanza, Municipality of
Loreto, Dinagat Province
340 MN759245
Limnonectes magnus 3 RMB 8540 KU 309273 Samar Barangay San Rafael, Municipality of Taft,
Eastern Samar Province
MN759232
Limnonectes magnus 3 RMB 8707 KU 309274 Samar Barangay San Rafael, Municipality of Taft,
Eastern Samar Province
MN759235
Limnonectes magnus 3 RMB 7956 KU 309687 Camiguin Sur Sitio Kampana, Barangay Pandan,
Municipality of Mambajao, Camiguin
Province
MN759220
Limnonectes magnus 3 RMB 7971 KU 309691 Camiguin Sur Sitio Kampana, Barangay Pandan,
Municipality of Mambajao, Camiguin
Province
MN759221
133
ABRAHAM ET AL.— TAXONOMIC RESOLUTION OF THE LIMNONECTES MAGNUS GROUP

APPENDIX I Continued.
Species Field no. Catalog no. Island Locality Elevation (m)
GenBank accession numbers
16S LCT
a
CPT2 POMC
Limnonectes magnus 3 RMB 7976 KU 309696 Camiguin Sur Sitio Kampana, Barangay Pandan,
Municipality of Mambajao, Camiguin
Province
MN759222
Limnonectes magnus 3 RMB 8065 KU 309702 Camiguin Sur Sitio Kampana, Barangay Pandan,
Municipality of Mambajao, Camiguin
Province
MN759223
Limnonectes magnus 3 RMB 8096 KU 309707 Camiguin Sur Sitio Pamahawan, Barangay Pandan,
Municipality of Mambajao, Camiguin
Province
MN759224
Limnonectes magnus 3 RMB 8292 KU 309975 Dinagat Sitio Cambinlia (Sudlon), Barangay
Santiago, Municipality of Loreto,
Dinagat Islands Province
MN759225
Limnonectes magnus 3 RMB 8295 KU 309978 Dinagat Sitio Cambinlia (Sudlon), Barangay
Santiago, Municipality of Loreto,
Dinagat Islands Province
MN759226
Limnonectes magnus 3 RMB 8365 KU 309981 Dinagat Sitio Cambinlia (Sudlon), Barangay
Santiago, Municipality of Loreto,
Dinagat Islands Province
MN759227
Limnonectes magnus 3 RMB 8389 KU 309985 Dinagat Sitio Cambinlia (Sudlon), Barangay
Santiago, Municipality of Loreto,
Dinagat Islands Province
MN759228
Limnonectes magnus 3 RMB 8482 KU 309989 Dinagat Sitio Cambinlia (Sangay 2), Barangay
Santiago, Municipality of Loreto,
Dinagat Islands Province
MN759229
Limnonectes magnus 3 RMB 8520 KU 310181 Samar Barangay San Rafael, Municipality of Taft,
Eastern Samar Province
MN759230
Limnonectes magnus 3 RMB 8523 KU 314384 Mindanao Pasonanca Natural Park, Sitio Canucutan,
Barangay Pasonanca, Municipality of
Zamboanga, Zamboanga del Sur
Province
MN759089 MZ577250 MT631735 MT631746
Limnonectes magnus 3