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A HYBRID OF A SPECTACLED BEAR
(Tremarctos ornatus) AND AN ASIATIC BLACK BEAR
(Selenarctos thibetanus) BORN AT THE MARACAY
ZOOLOGICAL PARK, VENEZUELA
(MAMMALIA; URSIDAE)
EDGARDO MONDOLFI
Fundación para la Defensa de la Naturaleza
(FUDENA). Aptdo. 70.376. Caracas 1071.
Venezuela.
ERNESTO
O.
BOEDE
Parque Zoológico Las Delicias. Maracay.
Venezuela.
A male Spectacled bear (Tremarctos ornatus), captured in a forested
mountainous region of western Venezuela, which has lived for at least
sixteen years at the "Parque Zoológico Las Delicias", Maracay, Venezuela,
has been caged for several years with a female Asiatic black bear (Selenarctos
thibetanus), imported in 1964 through a dealer in Miami, Florida.
This pair of bear copulated frequently resulting in several pregnancies.
According to the keepers, all of these cubs died (with the exception of one
born on September 11, 1975), due to inadequate housing and the lack of a
maternity den.
The male offspring of this intergeneric cross, born in September of
1975, is at present living at the Maracay Zoological Park. This hybrid
bear, at the age of 6 1/2 years, is a healthy, vigorous, well grown individual.
The male parent (Fig. 1) shows the face, throat and chest markings
characteristic of the species Tremarctos ornatus. The female (Fig. 2) has
the crescent shaped white mark on the chest, the white lower lip, the rounded
erect ears and the conspicuous ruff around the back of the head, typical
of the species Selenarctos thibetanus. In this individual the tips of the toes
on the forefeet are white, with the exception of the fifth toe.
The hybrid bear (Fig. 3) is shiny black all over, except for the whitish
lower lip and jaw, and a very faint white vertical stripe in the middle of
A HYBRID OF A SPECTACLED BEAR TREMARCTOS ORNATUS. . . 145
the chest. The muzzle is blackish, as in the mother, the Asiatic black bear,
rather than brownish, as in the father, the Spectacled bear. It is also somewhat
longer and more tapered than the relatively short and thick muzzle of
Tremarctos ornatus, thus resembles more the female parent in this trait.
The ruff around the back of the head is noticeable, but slightly developed.
The rounded ears are raised more than those of the Spectacled bear. The
general appearance of this hybrid bear, calis to mind an American black
bear (Ursus americanus).
Another hybrid male cub of the same parents was probably born
between October and November of 1974. A study skin and skull of this
nursing cub are preserved in the mammal collection of the "Estación Bio-
lógica de Rancho Grande", Venezuela. The label contains the following
data: External measurements (in millimeters): total length, 365; tail, 30;
hindfoot, 65; ear, 30; weight 1,125 grams. This individual is completely
covered by a coat of black hairs with a slight reddish brown tinge, and
has a white spot on the lower jaw.
CONCLUSION
Interspecific hybrids of the American black bear (Ursus americanus)
and Brown bear (Ursus arctos) have been born at the London Zoological
Garden (
ZUCKERMAN
,
1953). Several hybrids of the Polar bear (Thalarctos
maritimus) and the Kodiak bear (Ursus middendorfii) have been born at
íhe National Zoological Park, Washington, D. C. (Davis, 1950). An
intergeneric hybrid of a sloth bear (Melursus ursinus) and a Malayan bear
(Helarctos malayanus) was born in 1966 at the Tama Zoo, Japan (D
ATHE
,
1965).
ROBINSON
(1972) gives a list of hybrid bears born in zoological
parks. Of those, six are hybrids between subspecies of Ursus arctos; two
are hybrids of Ursus americanus X Ursus arctos; four of Thalarctos mariti-
mus X Ursus arctos; one of Melursus ursinus X Helarctos malayanus; one
of Ursus arctos X Selenarctos thibetanus; and one a doubtful hybrid of
Melursus ursinus X Selenarctos thibetanus.
The intergenereric hybrid Tremarctos ornatus X Selenarctos thibetanus
described above, is of particular interest because of the great morphological,
karyological and biochemical differences between those genera of bears, and
could throw some light on the phylogenetic position of the Spectacled bear
(
MONDOLFI
,
in press). It should be pointed out that the diploid chromo-
some number of T. ornatus is 52, compared to 74 of S. thibetanus
(EWER, 1973). The biochemical characteristic of the blood utilizing serum
146 MEMORIA DE LA SOCIEDAD DE CIENCIAS NATURALES LA SALLE
albumin, indicates that Tremarctos ornatus is the most isolated species and
diverges more from other bears (SEAL et al., 1970).
Two contradictory points of view have been put forward in regard to
the taxonomic position of Tremarctos ornatus. It has been placed in a
subfamily of its own (Tremarctinae) by the paleontologists
KURTÉN
(1966)
and
THENIUS
(1976); on the other side,
SIMP SON
(1945) stated that:
"The generic separability of Tremarctos from Ursus is not universally ad-
mitted and its subfamily separation is clearly excessive. Moreover there is
the anomalous position of Selenarctos, apparently midway between Tre-
marctos and Ursus. All living ursid genera are very closely allied, at least
as closely as is indicated by placing in a single subfamily in a balanced
classification. There are only a few genera and their finer grouping is not
a practical aid or requirement".
ACKNOWLEDGEMENTS
Thanks are due to Carlos Díaz, foreman; Simón Hernández, keeper;
and veterinarian José R. Torrealba, Director of the "Parque Zoológico
Las Delicias", Maracay who provided information about the history of
the bears kept at that Zoo. We are also grateful to Dr. Devra G. Kleiman
for reading the manuscript.
RESUMEN
Se describe un ejemplar híbrido de Oso de Anteojos (Tremarctos or-
natus) X Oso Negro Asiático (Selenarctos thibetanus), de sexo masculino,
nacido en Septiembre, 1975 en el Parque Zoológico Las Delicias, Maracay.
El padre es un oso de anteojos (Tremarctos ornatus) capturado en una lo-
calidad montañosa del oeste de Venezuela, la madre es una osa negra asiá-
tica importada de Miami, Florida, USA.
El híbrido, de sexo masculino, a los 6 1/2 años de edad, es un animal
saludable, con buen desarrollo. Su pelaje es negro brillante uniforme, a
excepción del labio inferior y la quijada que son blancos y de una muy
tenue raya vertical blanca en medio del pecho. El hocico es negro
1
al igual
que el de la madre, alargado y más agudo, asemejándose en esto al oso
negro asiático, ya que en el oso de anteojo el hocico es más bien corto y
relativamente grueso. El collarín de pelos negros largos alrededor del cue-
A HYBR1D OF A SPECTACLED BEAR TREMARCTOS ORNATUS. . , 147
llo detrás de la cabeza, característico del Selenarctos thibetanus, es
conspicuo en el híbrido, aunque está poco desarrollado. La
apariencia general del híbrido recuerda al Oso Negro
Norteamericano (Ursus americanus). Un osezno híbrido, hijo de los
mismos progenitores del ejemplar arriba descrito, el cual nació
probablemente entre Octubre y Noviembre de 1974, murió corto
tiempo después. Este ejemplar está preservado en la colección de
mamíferos de la Estación Biológica de Rancho Grande, Estado Aragua.
En algunos Parques Zoológicos europeos, de los Estados Unidos
de Norte América y del Japón han nacido híbridos de cruzamientos
entre diversas subespecies del Oso Pardo (Ursus arctos) e híbridos
interespecíficos del Oso Pardo X Oso Negro Norteamericano (Ursus
americanus), así como también híbridos intergenéricos del Oso Polar
(Thalarctos maritimus) X Oso Pardo (Ursus arctos), del Oso
Benzudo de la India (Melursus ursinus) X Oso Malayo (Helarctos
malayanus) y del Oso Pardo X Oso Negro Asiático (Selenarctos
thibetanus).
El ejemplar híbrido de Tremarctos ornatus X Selenarctos
thibetanus, que nació y vive en el Parque Zoológico de Las Delicias,
es de particular interés teniendo en cuenta la gran diferencia en las
características morfológicas, cariológicas y bioquímicas de los
progenitores: Tremarctos ornatus y Selenarctos thibetanus. A este
respecto cabe señalar que el número di-ploide de cromosomas en T.
ornatus es de 52, mientras que en S, thibetanus es de 74.
Dos puntos de vista contradictorios han sido expuestos en
relación a la posición taxonómica del oso de anteojos (Tremarctos
ornatus). Ha sido colocado en una subfamilia: Tremarctinae, por los
palentólogos
KURTÉN
(1966) y
TH ENIUS
(1976). Por otra parte el
paleontólogo
SIMPSON
(1945) opina que: "La separación genérica
de Tremarctos de Ursus no está admitida por todos y que su
separación en una subfamilia aparte es claramente excesiva. Más aún,
está la anómala posición de Selenarctos, aparentemente intermedia entre
Tremarctos y Ursus. . .". El reciente análisis de la posición
taxonómica y de la filogenia de Tremarctos ornatus (MON-
DOLFI
,
en
prensa), tiende a confirmar la opinión de
SIMPSON
de que la
inclusión de Tremarctos en una subfamilia diferente de la familia
Ursidae no se justifica, pero sí debe aceptarse la separación genérica del
Tremarctos, teniendo en cuenta sus singulares características anatómicas,
caryológicas y serológicas.
148 MEMO RIA DE LA SOCIEDAD DE CIENCIAS NATURALES LA SALLE
REFERENCES
DATHE, H.
1975 — In Grzimeks Animal Life Encyclopedia. Vol. III, 12, Mammals.
N.Y.
DAVIS, M.
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449-450.
EWER, R. F.
1973 — The Carnivores. Cornell University Press, N. Y.
KURTEN, B.
1966 — Pleistocene bears of North America 1. Genus Tremarctos, Spec-
tacle bears. Acta Zool. Fennica, 115: 1-120.
MONDOLFI, E.
— The feet an baculum of the spectacled bear, with comments on
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ROBINSON, R.
1972 — Hybridization among the Ursidae. Carnivore Genetics Newsletter
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SEAL, U. S., N. I. PHILLIPS, A. W. ERICKSON
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1945 — The principles of classification and a classification of mammals.
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THENIUS, E.
1976 — Zur stammesgeschichtlichen von Tremarcfos (Ursidae, Mammalia).
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ZUCKERMAN, C. B.
1953 — The breeding seasons of mammals in captivity. Proc. Zool. Soc.
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