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Endangered
Chile Darwin's Frogs
Is
the Chile Darwin's Frog (Rhinoderma rufum)
still alive?
Dr.
Klaus Busse
Zoologisches Forschungsinstitut und Museum Alexander Koenig
Adenauerallee 150–164
53113 Bonn
T
he
frogs of the genus Rhinoderma live in
the temperate humid forests of the southern part of South-America. They do not
inhabit tropical latitudes, but regions with a moist climate of moderate
temperatures especially in the western slope of the Andes. This corresponds to
south central Chile and to a small extent of Argentina. There they dwell in
forests of southern beech (Nothofagus),
some Lauraceae, Proteaceae, Myrtaceae and others. They became popular or even
famous due to the special way by which they reproduce. Their parental care is
unique among frogs. Rhinoderma is the
only batrachian genus which broods the tadpoles inside the vocal pouch. An
equally sophisticated brood care system can be found only in the Australian
genus Rheobatrachus. These frogs even
rear their offspring in the stomach (Tyler
1983, 1984; reproductive biology in frogs in general see Duellmann
& Trueb 1986, Crump
1994).
For
many years I keep a breeding stock of Rhinoderma
darwinii in Bonn. They are held in outdoor terrariums and they reproduce
every year. As a consequence of this I was invited to a congress in Santiago de
Chile in December 2001, together with the editor of the German REPTILIA, Heiko
Werning. The subject of the meeting was „ A seminar on breeding of Chilean
fauna in captivity“. Since I have kept only this one species, in my own
experience I was only able to report on R.
darwinii. In this presentation I referred to my aim of keeping also the
second species of the genus, R. rufum
which is far rarer and much less is known about its habits. As my aim is to make
comparative studies of behaviour, I complained that I have not been able to find
it in the wild, despite considerable efforts
in search of it. In the discussion that followed, some of the Chilean
colleagues argued that R. rufum is
considered as already extinct. But just this shouldn’t be true! Having in mind
this alarming background Heiko Werning and myself discussed the problem during
the congress and also consulted a number of Chilean colleagues, in order to
start a project with the goal of clarifying if some natural populations of R. rufum may have survived, and if so, to try to promote the
protection of its natural environment. Furthermore, a breeding programme can be
implemented if some individuals can be acquired. At the same time we want to
clarify the actual status of the species R.
darwinii, which in Chile is considered as „endangered“, and we want to
improve the efforts of captivity breeding. In any case, the situation of
rhinoderms is very serious: In the worst of all cases one of both known species
of these singular frogs could be already extinct, while the second one is
severely threatened. Hopefully there may be a chance for both species, if we do
something for their survival!
On
Systematics and Nomenclature of Rhinoderma
The
species Rhinoderma darwinii was
described by Duméril
& Bibron (1841) (see also Bell
1943). It was done on the basis of specimens collected by Charles
Darwin during his voyage around the World on the „Beagle”. The name
of this species remained the same from the beginning and is unquestionable.
The
second species Rhinoderma rufum has
caused some confusion among taxonomists. In 1902, the director of the Museum of
Natural History in Santiago de Chile, R. A. Philippi,
described a frog, which he called Heminectes
rufus. As locality he mentioned „the surroundings of Lago Vichuquén“.
This is a lake in
the coastal district westward of
Curicó. There has been little attention paid to this species in
literature, which probably may be due to the reason, that it has passed quite
unobserved, as it is very similar in appearance to R.
darwinii and it ever has been the rarer of the two species. Barros
(1918), dealt in more detail with this frog, although he thought of it as
belonging to the more common species R.
darwinii. Even Cei
(1962), considered the species described by Philippi
as a local form of R. darwinii.
Lastly, based on studies by Jorquera
et al. (1972, 1974) it was finally realised, that this view could no
longer be sustained.
These authors, primarily interested in embryology and the elaboration of
a developmental table, found fundamental differences in egg- and larval
development, when they compared individuals from Valdivia with those from
Concepción. While the former stay in the vocal pouch of the father until the
end of metamorphosis, the latter, after a short stay in the vocal pouch pass
through a long lasting free living tadpole stage, before transforming into
froglets (details see below).
At
last it was Formas
et al. (1975) ( see also Formas
1981) who drew the conclusion that they were dealing with two different species.
Based on the developmental differences this conclusion is more than justified.
Additionally, both species are, or at least were, living in simpatry near
Concepción. As it often occurs in systematics, thereafter also differences
between the adults became evident. The toes of R.
rufum are more conspicuously webbed, the colour pattern of the under surface
of feet is not as contrastfully coloured as the ones of
R. darwinii, these having a
more pronounced heel appendage, and in contrast, a less developed
metatarsal tubercle. The nomenclatural consequence of the finding that two
species exist is, that the generic name Heminectes
given by Philippi could
not be kept, because doubtless both species belong to Rhinoderma. The species name rufus
changes into rufum, because Rhinoderma
is (grammatically) neutral.
In
English for R. darwinii the vernacular
name „Darwin's frog“ has established, in Spanish it is „sapito de
Darwin“ or „ranita de Darwin“. In Spanish there is no fully established
vernacular name for R. rufum, but
there is a good candidate:
„sapito vaquero“ already used by Barros
(1918). Although he confused it with R.
darwini, ignoring the existence of the second species, based on geographical
reasons, he must have dealt with R. rufum.
He used a popular local name, which
is not in use for the more southern
R. darwinii, Also Kilian
(1965: 187) in a time, when
only one Rhinoderma species was
recognised, mentioned that he name "sapito vaquero" is in use only for
the northern populations, which is a hint in the same direction. All this is
reason enough to restrict this name to the species R.
rufum. In German (see Busse
2002b) apart from the name in honour of Charles
Darwin there is a name referring to the frog's nose:
„Nasenfrosch“. As this name refers to the whole genus, there was no
harm to translate part of the original name of the second described species „Heminectes“
as „Halbschwimmer-Nasenfrosch“ which means something like „semi-swimming
rhinoderm“, this could be interpreted in a double meaning: One referring to
the toes, that contrary to the unwebbed ones of R.
darwinii are partially webbed. The other is a coincidence making sense with
the larva, which lives as a free swimming tadpole during part of its
development. It is related to the name given by Philippi
(1902), which this year has its centenary baptism anniversary. A problem
is the English name: „Chile Darwin's-frog“ proposed by Frank
& Ramus (1996: 114). It is quite misleading, because the name
„Darwin's-frog“ is used for and should be restricted to R.
darwinii, which like R. rufum equally
is a Chilean inhabitant.
Some on
Reproductive Biology
In
the first species of Rhinoderma being
described R. darwinii, it was noticed
early on, that some individuals carried tadpoles inside their body. Accordingly
they were thought to be females, until the Spanish scientist Jimenez
de la Espada (1872) recognised that the „pregnant“ individuals were
males which reared their tadpoles inside the vocal sac. Details of the
reproductive biology were complemented piece by piece up to recent time (for
further details see Busse
1989, 1991, 2002a). In the second Rhinoderma
species it was quite different: It was the knowledge of reproduction which
allowed confirmation of its distinctness at species level. A comparison should
help to demonstrate it:
Rhinoderma
darwinii
lays large eggs with abundant yolk (approx. 5–15 eggs with a diameter of about
3,6 mm). First they develop for 20 days outside the water, and hidden in moist
vegetation on the ground. When the tadpoles hatch they are taken by the male,
after which they are brooded for 34–60 days in the vocal pouch of the father
who releases them as metamorphosed froglets. The main part of the larval
development and metamorphosis takes place inside the vocal sac, they lack a free
living water dwelling tadpole stage.
Rhinoderma
rufum
lays considerably smaller eggs with less yolk, but in a more numerous clutch
(12–25 with a diameter of 2,5 mm, what means around 1/3 of the volume). They
develop during 7 days on a terrestrial environment. Then the fry is taken by the
male inside his vocal sac, but he carries his offspring only for two weeks,
after which they are released into the water in a relatively early tadpole
stage. As a consequence a considerable part of the larval development and growth
as well as the metamorphosis takes place in the water as in most other anurans.
This takes about three months (approx. 120 days). Considering that there is an
internal and an external developmental span, they have an intermediate brood
care mode. Just this intermediate brood biology model makes R. rufum outstandingly interesting. More detailed studies may help
to understand how oral brood care in rhinoderms has evolved. And this species
could be extinct?.... No, it ought not to be allowed!
Prospective
search of historical and present occurrence
There
is an urgent need to clarify the case. To proceed efficiently, before searching
in the field, we are researching at different levels, trying to get as many
hints as possible on where there may be some places with actual occurrence of R.. rufum or at least where they have occurred in the past:
literature research, receipts from collections in museums, interviews etc. Part
of this has already been done or is still being undertaken.
In
literature naturally there is some data. Unambiguous proofs were provided by Formas
et al. (1975). Another one is the locality given by Philippi
(1902) in his original description. It is quite sure that the R.
darwinii mentioned by Barros
(1908) really are R. rufum. Penna
& Veloso (1990) published sonagrams of the call of diverse Chilean
frogs. Their tape recordings of R. rufum
were done in October 1980 near Concepción, accordingly this species at least at
that time must have still existed in that place.
In
addition to data from literature in a second approach level, collecting
localities of museum specimens may help. The collections I could reach up to
now, were rummaged through in search of R.
rufum. The search of the Museum of Natural History in Santiago de Chile gave
a negative result. Although this taxon was described in this museum, Formas
et al. (1975) could also not find the types of Philippi
there. For this reason they designated a specimen collected by them in
the type locality Vichuquén as a neotype. This was deposited at the Zoological
Institute in Valdivia, where Formas has several more specimens from different
localities. I have been at the Berlin Museum of Natural History where also no R.
rufum could be found. In our institute (Museum Koenig , Bonn) among about 70
exemplars of R. darwinii, 6 R. rufum were found, who would have hought it? Originally they had
been catalogued as R. darwinii. One
must be aware that such misidentification may have occurred in many
herpetological collections, especially when they date from before the
revalidation by Formas
et al. (1975), therefore they should be examined carefully. Our specimens
in Bonn had certainly been catalogued with the wrong collecting place Santiago
de Chile, but by chance I knew the collector. But, the childhood reminders I had
of E. Timmermann
dating from the time I lived in Chile, have scarcely
been of use, and his descendants, not much interested in natural
history, couldn't report anything to correct the finding locality.
This
leads us to the third level of approach, the personal questioning: I already
have asked some Chilean colleagues. Also the „guardaparques“, the rangers of
the Chilean natural reserves and national parks of
CONAF (= Corporación Nacional Forestal) are a source of information.
They are fairly well instructed about the fauna in their area. At this level
there more work is lying ahead.
One
stroke of luck was, that the airplaine I took during my last stay in
Chile chose its route over Concepción to Santiago just over the ridge of the
Coastal Andes. So I was able to have a short glance at the small valleys
draining in their short westward course to the Pacific. I was somewhat
concerned, how dry it was looking and how widely the areas if forested, were
artificially reforested mainly with pine (Pinus
radiata) or eucalyptus (Eucalyptus
globulus). But at least I saw some smaller gallery forests along the
streams, which presumably are composed of native trees, and in which there may
be some probability to find some rhinoderms. It was striking how
impassable the western slope of the coastal range looked. It seems hard to reach
and if at all, only with a good off road vehicle.
Search in
the Field
As
the fourth and most important action level, all the possible biotopes mentioned
in literature and collection records should be visited from North to South. This
should take place during October and November, the presumed main activity season
of rhinoderms.
Also the little streams of the small fluvial systems mentioned will be included.
The same applies for the natural reserves of CONAF. In at least one of them, a
rare species of southern beech like the „ruil“ (Nothofagus
alessandrii) , which had been thought to be extinct, was found again and put
under protection.
For
R. darwinii in the field it had proved useful to search by sight as
well as acoustically. This procedure should also be applied to R.
rufum. We plan to provoke the frogs to respond by playing back their calls.
The co-ordinates of searched places and the ones where frogs were found will be
recorded by GPS and registered.
The
Chilean Ministry of Agriculture gave me permission to export six individual
frogs of each species. I could proceed only for R.
darwinii. The frogs were brought to Bonn and joined to our breeding
population in order to prevent possible inbreeding disadvantages. If we will
find R. rufum we will act very
carefully. We will give the first priority to the protection of the natural
habitat of the endangered species, and a second one to the effort to breed it in
captivity. On the other hand a better knowledge of the breeding biology of this
species can be of great importance for its protection. This reason justifies the
sampling of some individuals from the wild in order to breed them in terraria.
Call for
Donations and Financial Support
The
Chilean Ministry of Agriculture, Section of Renewable Natural Resources, showed
much interest in our project for which we thank Mr. Horacio Merlet and Mr. Agustín
Iriarte. Also, Chilean zoologists as well as the Metropolitan Zoo Santiago
showed interest. They have assured their assistance. Nevertheless the
impassability of the landscape remains a problem. We will need a good off road
vehicle and in some cases we probably will need to use the logistics of the
“forestal reserves”, what means a tight collaboration with CONAF. In Germany
the ZGAP (Gemeinnützige Zoologische Gesellschaft für Arten- und
Populationsschutz: Zoological Society for Protecion of Species and Populations)
spontaneously agreed to support the project. Firstly they provide an account for
financial donations and furthermore they promised to accompany the project with
their help. Donations for the project are tax deductable.
For
the performance of such an expedition and for its management a financial effort
is necessary, which cannot be achieved by an individual initiative. Therefore
REPTILIA adopted this project and we ask you for your help. The project has a
good chance of success, and additionally it would be a proof that terraria
keepers are not simply consumers of animals, but most of all they are active
protectors of the fauna. Please help us by means of your donation . Even
a small sum helps!
Literature
-
Barros,
R. (1918) : Notas sobre el sapito vaquero (Rinoderma
darwinii). - Rev. Chil. Hist. Nat. 22: 71-75.
-
Bell,
T. (1843): Reptiles 5: pp.1-51 in: Darwin, C. (ed.): The Zoology of the
Voyage of HMS
Beagle, under the Command of Capt. Fitzroy, R. N. During 1832-1836 . -
London, Smith Elder Publ.
-
Busse,
K. (1989):
Zum Brutpflegeverhalten des Nasenfrosches Rhinoderma
darwinii (Anura: Rhinodermatidae). - Tier u. Museum 1(3): 59-63.
-
-
(1991): Bemerkungen zum Fortpflanzungsverhalten und zur Zucht von Rhinoderma darwinii: Balz
bis Eiablage. - Herpeto-fauna 13(71): 11-21.
-
-
(2002a): Fortpflanzungsbiologie von Rhinoderma
darwinii (Anura:
Rhinodermatidae) und die stammesgeschichtliche und funktionelle
Verkettung der einzelnen Verhaltensabläufe. - Bonn. zool. Beitr. 51 (in
press).
-
-
(2002b): Nasenfrösche in Gefahr: Gibt es in Chile noch den
Halbschwimmer-Nasenfrosch (Rhinoderma
rufum)? REPTILIA 7(3): 3–8.
-
Crump,
M.L. (1994): Parental care. - pp. 518-567 in: Heatwole, H. & Barthalmus,
G. (eds.): Amphibian biology. - Surrey Beatty & Sons PTY Ltd. Norton
N.S.W.
-
Cei,
J.M. (1962): Batracios de Chile. - Editorial Universidad de Chile, Santiago,
236 pp.
-
Duellman,
W.E. & L.
Trueb (1986): Biology of Amphibians. - McGraw-Hill, Inc, 670 pp.
-
Duméril,
A.M.C. & C. Bibron (1841):
Erpétologie générale. - Paris 8(3), 792 S.
-
Formas,
R. (1979): La Herpetofauna de los bosques temperados de Sudamérica. - In W.
Duellman (ed.): The South American Herpetofauna: Its Origin, Evolution and
Dispersal. - Monograph Mus. Nat. Hist. Kansas 7: 341-369.
-
Formas,
R., E. Pugin, & B. Jorquera (1975):
La identidad del batracio chileno Heminectes
rufus Pilippi, 1902. - Physis, C,
34(89): 147-157.
-
Frank,
N. & E. Ramus (1996):
A complete Guide to Scientific and Common Names of Reptiles and
Amphibians of the World.- N G publishing Inc. Pottsville 377pp.
-
Jiménez
de la Espada, D.
M. (1872): Sobre la reproducción de Rhinoderma
darwinii. - An. Soc. esp. Hist. Nat. 1: 139-151.
-
Jorquera,
B., E. Pugin & O. Goigoechea (1972):
Tabla de desarrollo normal de Rhinoderma
darwini. - Arch. Med Vet. 4(2): 5-19.
-
Jorquera,
B., E. Pugin & O. Goigoechea (1974):
Tabla de desarrollo normal de Rhinoderma
darwini (Concepción). - Bol. Soc. Biol. Concepción 48: 127-146.
-
Jorquera,
B., E. Pugin, O. Garrido, O. Goigoechea & R. Formas (1981):
Procedimiento de desarrollo en dos especies del género Rhinoderma.
- Medio Ambiente 5(1/2): 58-71.
-
Penna,
M. & A. Veloso (1990):
Vocal diversity in frogs of the South American temperate forest. - J.
Herpetol. 24(1): 23-32.
-
Philippi,
R.A. (1902): Suplemento a los Batraquios chilenos descritos en la Historia Física
y Política de Chile de Don Claudio Gay. - Santiago de Chile.
-
Tyler,
M.J. (1983): The gastric brooding frog. - Croom Helm, London & Canberra,
163 pp.
Dr. Klaus
Busse, Zoologisches Forschungsinstitut und Museum Alexander Koenig;
Adenauerallee 160, 53113 Bonn, Deutschland.
E-Mail: k.busse.zfmk@uni-bonn.de
(*)Fuente:
Batracios de Chile José Miguel Cei. Editorial Universidad de
Chile. ISBN 956-00-2481-4
Diversidad Biológica de Chile
Javier
A. Simonetti et al. Editorial CONICYT, Chile.
Laboratorio
de Herpetología Universidad de Concepción.
Museum Alexander
Koenig; Adenauerallee 160,
53113 Bonn, Deutschland. Dr. Klaus Busse,
Zoologisches Forschungsinstitut und E-Mail k.busse.zfmk@uni-bonn.de
Páginas personales.
Dr. Helen Díaz. Universidad de
Concepción.
Amphibian
Species of the World V2.21 Database
Diseño
listado: Huiña-pukiosÓ2002.
Al ser utilizada esta Web Page, por favor citar la fuente.
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