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Introduction
Gephyromantis is a monophyletic genus within
the family Mantellidae that contains frogs of largely
brownish coloration, which primarily inhabit the leaf
litter in the rain forests of Madagascar (Glaw and
Vences, 2006). Five subgenera are currently recognized
(Duboimantis, Phylacomantis, Laurentomantis,
Vatomantis, and Gephyromantis). However, a recent
molecular study using both mitochondrial and nuclear
genes revealed that the subgenus Gephyromantis is
monophyletic only after exclusion of G. klemmeri
Guibé, 1974, and that Duboimantis Glaw and Vences,
2006 includes two strongly supported clades of uncertain
relationships (Kaffenberger et al., 2012). The focal
group of the present study, the subgenus Vatomantis, is
monophyletic and is the sister group to G. klemmeri +
Laurentomantis Dubois, 1980.
The subgenus Vatomantis contains three species
of small-sized frogs from north-eastern Madagascar
(Vences, Glaw and Andreone, 1997; Vences, Glaw and
Marquez, 2006; Glaw and Vences, 2006). Gephyromantis
webbi and G. silvanus were originally described from
the island of Nosy Mangabe, with G. webbi being
additionally found on the adjacent mainland (Grandison,
1953; Vences, Glaw and Andreone, 1997; Glaw and
Vences, 2007). According to current knowledge (Glaw
and Vences, 2007; Gehring, Ratsoavina and Vences,
2010), G. rivicola has a distribution from Marojejy
south to the Masoala Peninsula at elevations from 0-
700 m, while Gephyromantis webbi and G. silvanus live
in coastal lowland forests between Andranofotsy and
Ambodiriana below 100 m elevation.
The three frog species in the subgenus Vatomantis are
typically 22–33 mm in size (snout-vent length) and can
be distinguished from other species of the genus due to
their olive green coloration (Glaw and Vences, 2006).
Vatomantis frogs are usually found within 20 m from
streams containing large mossy stones and boulders.
Species of the subgenus Vatomantis call during the
day (G. webbi) and during the evening and night (G.
silvanus), with G. rivicola being known to show both
diurnal and nocturnal calling behaviour (Vences, Glaw
and Andreone, 1997; Glaw and Vences, 2006). The
calls of G. webbi from its type locality, Nosy Mangabe,
Herpetology Notes, volume 7: 67-73 (2014) (published online on 4 February 2014)
Descriptions of the advertisement calls
of three sympatric frog species in the subgenus Vatomantis
(genus Gephyromantis) from Madagascar
Joana Sabino-Pinto1, Christopher J. Mayerl1, Willem R.M. Meilink1, Diana Grasso1,
Constantijn C.B. Raaijmakers1, Valerio G. Russo1, Maud Segal1, Gwij Stegen1, Jonathan Clegg1,
Achyuthan N. Srikanthan1, Frank Glaw2, Miguel Vences3,4
1Master studies in Herpetology, Vrije Universiteit Brussel, 2
Pleinlaan, B-1050 Brussels, Belgium.
2Zoologische Staatssammlung München, Münchhausenstr. 21,
81247 München, Germany.
3Technische Universität Braunschweig, Zoological Institute,
Mendelssohnstr. 4, 38106 Braunschweig, Germany.
4Corresponding author; e-mail: m.vences@tu-bs.de
Abstract. Frogs of the subgenus Vatomantis Glaw and Vences, 2006 form a monophyletic group within the genus Gephyromantis
Methuen, 1920 in the family Mantellidae, endemic to Madagascar and Mayotte. In anurans, vocalization is often a valuable
character complex for taxonomical classification since it is an efficient premating isolation mechanism, and to add to the
bioacoustic knowledge on Madagascar’s frogs we here provide a description of the advertisement calls of three sympatric
species in the subgenus Vatomantis: Gephyromantis webbi (Grandison, 1953), G. rivicola (Vences, Glaw and Andreone, 1997)
and G. silvanus (Vences, Glaw and Andreone, 1997). Calls of all three species were recorded the same day at the same
temperature, in sympatry along a small stream in a forest fragment near Andranofotsy, allowing for a direct comparison. The
call of G. webbi is the shortest, with long inter-call interval length. Overall, the calls of G. rivicola and G. silvanus show more
similarities to one another than to that of G. webbi.
Key Words: Bioacoustics, Mantellidae, rivicola, silvanus, webbi, Andranofotsy.
Joana Sabino-Pinto et al.
68
as well as call recordings of all three species from
Andranofotsy, have been documented on an audio-
CD (Vences, Glaw and Marquez, 2006). However, the
bioacoustic analysis and description so far refers to the
G. webbi recordings from Nosy Mangabe only (Glaw
and Vences, 1992; Vences, Glaw and Andreone, 1997)
and is not very detailed.
It is known that calls in anurans play an important
role in attracting females, advertising the position of
an individual to conspecific males, defending calling
sites and announcing a more aggressive behaviour
(Wells, 1977, 2007; Duellman and Trueb, 1994; Ryan,
2001). Advertisement calls of anuran males are species-
specific, and comparative bioacoustic analyses of frog
vocalizations are valuable tools in the discovery of
new taxa, assessment of taxonomic rank and species
identification (Kok and Kalamandeen, 2008). The
application of bioacoustics in an integrative taxonomic
approach is especially important in tropical areas, as it
opens the door to new frontiers of data exploration that
may increase the rate of species discovery (Padial and
De la Riva, 2009). The sometimes drastic, bioacoustic
differences between similar species may act as an
efficient premating isolation mechanism (Vieites et al.,
2012). As body temperature has an impact on the call
of anurans, this should also be considered in taxonomic
comparisons among closely related species (Schneider
and Sinsch, 2006). In mantellids, as well as in other
anurans, temperature mainly influences inter-note
intervals and note repetition rate but affects note length
only weakly (Glaw et al., 2010; Vieites et al., 2012).
Here we describe and compare the calls of the three
closely related Gephyromantis species, all classified in
the subgenus Vatomantis (G. webbi, G. rivicola and G.
silvanus)
Materials and Methods
All advertisement calls of the three species analysed
here were recorded in close syntopy along a stream
near Andranofotsy (-15.4353, 49.8439, 85 m a.s.l.), a
coastal site near the small town of Maroantsetra, on 17
December 2001 during the afternoon and in the early
evening (15−19 h), at a temperature of 25.4°C, by M.
Vences. Calls were recorded in the field using a Sony
WM-D6C tape recorder with an external microphone
(Vivanco EM 238). Recordings of the three males
were made at a distance of about 100-150 cm from the
frogs. For G. silvanus and G. webbi, recordings of 10
s and 30 s were selected for analysis whereas for G.
rivicola, 60 s of continuous calling was selected, each
recording probably representing one male. Recordings
were digitized at sampling rate 22.05 kHz and 16-bit
resolution and computer-analysed using the software
CoolEdit Pro v. 2.0 (Syntrillium Software Corporation).
Frequency information was obtained through Fast
Figure 1. Oscillograms of G. silvanus (left) and G. webbi (right). Red-brown denotes one call, green represents one pulse, A is the
inter-call interval, and B is the pulse interval. Each picture is a zoomed in view of the one above it and graphs are not to scale.
Fourier Transformation (FFT; width 1024 points).
Spectograms were obtained at Hanning window function
with 512 bands resolution. The temporal parameters
“calls” and “pulses” are used according to Fig. 1. Call
descriptions follow Vences et al. (2002) in structure and
terminology. The analysed call recordings are deposited
in full length in the Fonoteca Zoologica (www.fonozoo.
com) of the Museo Nacional de Ciencias Naturales of
Madrid, Spain (CD Code: MV07B-CD68; recording
numbers: G. rivicola: 3016, 3030; G. silvanus: 3017-
3025; G. webbi, 3026-3029). Those recordings used
for analysis herein are the ones included in the CD of
Vences, Glaw and Marquez (2006), and deposited in the
Fonoteca under numbers 3016 (G. rivicola), 3025 (G.
silvanus), and 3026 (G. webbi).
Dorsolateral and ventral views of representative
frogs from the three species were photographed shortly
after capture to ensure optimal representation of their
natural coloration (Figs. 2-3). These specimens were
euthanized with chlorobutanol, and subsequently fixed
in 7% formalin solution and preserved in 70% ethanol.
Voucher specimens were catalogued in the Zoologische
Advertisement calls of three sympatric frog species in the subgenus Vatomantis 69
Figure 2. Dorsolateral and ventral views of adult males of Gephyromantis webbi, G. rivicola and G. silvanus, all photographed on
17 December 2001 near Andranofotsy, Madagascar.
Staatssammlung München (ZSM), Germany for permanent
storage. MV refers to field numbers of Miguel Vences.
All specimens listed were collected at the same time and
site as call recordings were made, but recordings cannot
be assigned reliably to any specific voucher because the
recorded individuals, although observed calling, could not
be captured immediately upon calling.
Results
Call descriptions of G. webbi, G. rivicola,
and G. silvanus
Calls of G. webbi were emitted during the day from
mossy stones along a stream in rainforest, close to the
recording site of G. rivicola and G. silvanus. Calls from
G. rivicola were emitted during the day as well from
rocks and the ground at hidden positions in an area
where large boulders formed caves near a small stream in
rainforest. Finally, the calls of G. silvanus were emitted
in the late afternoon from within cave-like formations
between large boulders, close to a small rainforest
stream. Calling specimens of this latter species were
very secretive but could be observed at one occasion.
All males were calling more or less continuously.
Gephyromantis webbi (Grandison, 1953)
Toamasina Province: Andranofotsy. Four males,
ZSM 136/2002 (MV 2001.1436), ZSM 137/2002 (MV
2001.1437), ZSM 181/2002 (MV 2001.1376) and
ZSM 182/2002 (MV 2001.1377); two females, ZSM
138/2002 (MV 2001.1438) and ZSM 139/2002 (MV
2001.1439) .
The call is reminiscent of the sound made by two stones
smacking together in quick succession, generally in
triplets, with the middle pulse having the highest energy.
Calls were recorded from one of the four collected
males and consisted of three pulses (n=3 calls) (Fig. 4).
Call duration was 496-571 ms (523±42 ms, n=3 calls),
duration of intervals between calls was 1697-2155 ms
(1926±324 ms, n=2 calls). Pulse duration was 55-86 ms
(73±12 ms, n=9 pulses), duration of intervals between
pulses was 124-132 ms (129±3 ms, n=6 intervals).
Frequency range was 1470-8879 Hz, with a dominant
frequency range of 2756-4478 Hz (3968±341 Hz, n=3
calls).
Gephyromantis rivicola (Vences, Glaw and Andreone, 1997)
Toamasina Province: Andranofotsy. Four males,
ZSM 119/2002 (MV 2001.1450), ZSM 120/2002 (MV
2001.1451), ZSM 179/2002 (MV 2001.1380) and ZSM
180/2002 (MV 2001.1381).
The frog call could be perceived as marbles rapidly
clicking together. Calls of one male have 16-19 pulses
(17±1 pulses, n=5 calls) (Fig. 5). Call duration was
1113-1543 ms (1257±169 ms, n=5 calls), duration
of intervals between calls was 79-109 ms (97±11 ms,
n=5 intervals). Pulse duration was 31-63 ms (46±6 ms,
n=50 pulses), duration of intervals between pulses was
18-56 ms (34±9 ms, n=50 intervals). Frequency range
was 1970-8263 Hz, with a dominant frequency range
of 3229-4995 Hz (4689±341 Hz, n=5 calls). The pulses
have descendant modulation, with the highest sound
energy concentrated at the start of a pulse, in a short
period with duration of 12 ms. Immediately after this
condensed burst of sound, the pulse energy decreases
rapidly.
Joana Sabino-Pinto et al.
70
Figure 3. Specimens of Gephyromantis silvanus, photographed in their habitat (a small cave) on 17 December 2001 at night, near
Andranofotsy, Madagascar.
Gephyromantis silvanus
(Vences, Glaw and Andreone, 1997)
Toamasina Province: Andranofotsy. Three males,
ZSM 131/2002 (MV 2001.1446), ZSM 177/2002 (MV
2001.1378) and ZSM 178/2002 (MV 2001.1379); one
female, ZSM 1137/2002 (MV 2001.1447); one juvenile,
ZSM 130/2002 (MV 2001.1445).
The call (Fig. 6) sounds like an old door being closed,
or a spoon being dragged along a washboard. The two
recordings are analysed separately because of their
marked difference. There is however no indication that
the two calls were of fundamentally different types
with different functions, such as territorial vs. mating.
Instead, we hypothesize that the second recording
includes simultaneously emitted calls of two males and
therefore is difficult to analyze. We consider the first
recording most reliable and informative for taxonomic
purposes, hence our focus on the call parameters derived
from it. Since calls were emitted from within a cave
it was not possible to ascertain which individual has
been recorded. We succeeded only in one single case
to directly observe call emission and thereby assign this
vocalization to G. silvanus, but the observed male could
be neither recorded nor collected as it was calling from
a deep fissure within the cave.
Recording 1 (single calling male): Call consisted of
49-57 pulses (53±4 pulses, n=3 calls). Call duration was
2143-2257 ms (2217±64 ms, n=3 calls), duration of
intervals between calls was 1088-2243 ms (1666±817
ms, n=2 intervals). Pulse duration was 31-49 ms (41±2
ms, n=10 pulses), duration of intervals between pulses
was 14-33 ms (24±6 ms, n=10 intervals). Frequency
range was 1492-3776 Hz, with a dominant frequency
range of 2067-3100 Hz (2526±526 Hz, n=3 calls).
Recording 2 (antiphonal call): Calls consisted of 99-
117 pulses (107±6 pulses, n=7 calls). Call duration was
3152-4575 ms (4048±492 ms, n=7 calls), duration of
intervals between calls was 154-733 ms (381±207 ms,
n=6 intervals). Pulse duration was 22-37 ms (27±4 ms,
n=10 pulses), duration of intervals between pulses was
12-26 ms (19±4 ms, n=10 intervals). Frequency range
was 1131-4847 Hz, with a dominant frequency range of
1550-3445 Hz (2583±879 Hz, n=7 calls).
Advertisement calls of three sympatric frog species in the subgenus Vatomantis 71
Figure 4. Spectrogram (above) and oscillogram (below) of a
call of Gephyromantis webbi, recorded on 17 December 2001
at 24.5°C air temperature; near Andranofotsy, Madagascar.
Figure 5. Spectrogram (above) and oscillogram (below) of a
call of Gephyromantis rivicola, recorded on 17 December 2001
at 24.5°C air temperature; near Andranofotsy, Madagascar.
Figure 6. Spectrogram (above) and oscillogram (below) of a
call of Gephyromantis silvanus (recording 1 in text), recorded
on 17 December 2001 at 24.5°C air temperature; near
Andranofotsy, Madagascar.
Discussion
Despite their importance in the biology of anurans,
there is no standard methodology for describing calls.
The definitions used herein were suggested by Duellman
and Trueb (1994), and have been widely accepted and
used by many others (e.g., Kok, 2010; Lehtinen et al.,
2012; Kok et al., 2013). In this system, a call is defined
as the assemblage of acoustic signals produced in a
given sequence, a note is an individual unit of sound
contained within a call, and a pulse is an energetic
impulse in the temporal spectrum of a note. Due to their
species specificity, knowledge on the characteristics of
advertisement calls is integral in performing integrative
taxonomic work, such as in the identification and
discovery of species (Padial et al., 2010; Vences et al.,
2012). Furthermore, once the call of a species is known,
the information can be used in a variety of biological and
ecological studies such as measuring species diversity
by call analyses or determining a species reproductive
habitat by determining call locations (Funk et al.,
2011).
The sister subgenus to Vatomantis is Laurentomantis
(Kaffenberger et al., 2012). This latter subgenus inhabits
eastern and northern Madagascar and is composed of
small frogs, with single subgular vocal sacs, mainly
nocturnal activity, and in many species a remarkably
broad head and warty dorsal surface (Glaw and Vences,
2006, 2007). Six Laurentomantis species are currently
recognized, all of which have calls differing from
the species analyzed here. The call of G. malagasius
(Methuen and Hewitt, 1913) is composed of a single,
long, pulsed note with a low frequency, which can last
for as long as a 1.5 seconds (Vences et al., 2002). On
the other hand, the call of G. horridus (Boettger, 1880)
is composed of a fast sequence of unharmonious pulses
with 16 to 33 widely spaced pulses (Vences et al., 2002).
The calls of G. klemmeri and G. striatus (Vences, Glaw,
Andreone, Jesu, and Schimmenti, 2002) are similar to
the one of G. horridus although the former is faster
(Vences et al., 2006) and the latter has a maximum of
6 pulses per note (Vences et al., 2002). The call of G.
ventrimaculatus (Angel, 1935) is similar to the one of G.
striatus, but is slower and has a lower intensity (Vences
et al., 2002). Lastly, the call of G. ranjomavo Glaw and
Vences, 2011 is not yet recorded, but appears to consist
of a sequence of unharmonious, distinctly pulsed notes
(Glaw and Vences, 2011). The calls of G. webbi and G.
rivicola can be differentiated from all the calls associated
with the sister subgenus by being slower and by each
note being composed of less pulses in the former and
more pulses in the latter. The call of G. silvanus can be
differentiated by being longer and lasting for more than
two seconds. Given that most Laurentomantis calls are
composed by long series of pulses, the low number of
pulses and the slow repetition rate found in G. webbi
can be hypothesized to constitute a derived condition
within the (Laurentomantis, Vatomantis) clade.
In comparison with the calls of G. webbi from the
island Nosy Mangabe (described by Glaw and Vences
1992), which were recorded at similar temperature
(23°C) it is remarkable that these calls were composed
of up to 10 pulses whereas those from Andronofotsy
contained only three pulses. Remarkable but poorly
understood variation in call parameters is also evident
between the two recordings of G. silvanus suggesting
that further research is necessary to understand the
acoustic repertoire of Vatomantis species.
Acknowledgments. We are grateful to Augustin Sarovy for
his help during the fieldwork in Andranofotsy. This work has
been carried out in collaboration agreement of the Zoologische
Staatssammlung München with UADBA (Université
d’Antananarivo, Département de Biologie Animale). The
Malagasy authorities kindly granted research and export permits.
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Advertisement calls of three sympatric frog species in the subgenus Vatomantis 73