Albignac, Roland

Rumpler, Y.

Horizon / Pleins textes

Reprinted from AMERICAN JOURNAL OF P H Y S ~ ~ A L  ANTHROPOLOGY 
Vol. 42, No. 3, May 1975 Q The Wistar Institute Press 1975 
Intraspecific Chromosome Variability in a Lemur from the 
North of Madagascar: Lepilemur septen trionalis, 
species nova 
YVES RUMPLER AND ROLLAND ALBIGNAC 
Laboratoire d'Histologie, Embryologae-Cytog aet iGue,  Faculté de  Médecine, 
Université de  Madagascar, B. P. 375, Tananarive,-Malagasy Republic 
K E Y  WORDS Karyotype . Lemur chromosomes Cytogenetics 
Centric fusion. 
ABSTRACT A cytogenetical study of 25 Lepilemur from the north of Mada- 
gascar has given evidence for six karyotypes (with four diploid numbers). Four 
of the karyotypes with these diploid numbers-2N = 38, 2N = 36, 2N = 34 
-we believe evolved from one another by centric fusion; and two karyotypes 
resulted from the hybridization of two of these (2N = 37 and 2N = 35). The 
different karyotypes distinguish themselves clearly from those of other species 
of Lepilemur. We have named a new species, Lepilemur septentrionalis (sp. nov.) 
with four subspecies: L. s. andrafiamenensis (2N = 38), L. s. anlzaranensis 
(2N = 36), L. s. sahafarensis (2N = 36), and L. s. septentrionalis (2N = 34). 
The genus Lepilemur or sportive lemurs 
are endemic Malagasy lemurs, common 
all over the island. The classification, spe- 
cifically the nomenclature and taxonomy, 
of Lepilemur has been the subject of much 
controversy and discussion. We made a 
cytogenetical study of all lepilemurs to try 
to categorize each one clearly. In this 
paper, we present the karyotypes of dif- 
ferent lepilemurs from the forested areas 
from the north of Madagascar in Anka- 
rana, Andrafiamena, Montagne d'Ambre, 
and the forest of Sahafary. 
MATERIALS AND METHODS 
. We karyotyped 25 lepilemurs (10 males 
and 15 females) caught during six suc- 
cessive expeditions: three males in 1968, 
one on the first cliff on Ankarana, one 
south of Matsaborimanga, and one north 
of Andrafiabe; two females and one male 
on the Ankarana near Analamisondrota 
in 1969; two females and one male on 
Montagne d'Ambre in 1971; two females 
at the mouth of the Andrafiamena near 
Anjakely in 1972; and five males and nine 
females in the forest of Sahafary in 1972 
and 1973. 
Chromosome preparations were made, 
using the leucocyte cultivation method of 
Lejeune. For the karyotype analysis of 
AM. J. PHYS. ANTHROP., 42: 425-430. 
each animal we examined a minimum of 
ten mitotic metaphase plates in which 
the chromosomes were neither overlapping 
nor excessively contracted. 
RESULTS 
The lepilemurs in this study were found 
to have six different karyotypes with five 
different diploid numbers: 2N = 38,2N = 
37, 2N = 36, 2N = 35 and 2N = 34 (ta- 
ble l). A skin sample and a skull of each 
specimen have been left at the Museum 
d'Histoire Naturelle de Paris.l 
The first karyotype, 2N = 38, consists 
of one pair of medium sized submetacen- 
tric chromosomes, 17 pairs of acrocentric 
chromosomes, and one pair of sex chromo- 
somes in which the X is a medium sized 
metacentric and the Y a very, small acro- 
centric. The fourth pair of acrocentrics 
has a satellite on its distal extremi'ies. The 
acrocentric chromosomes decrease in size 
regularly from the first to the seventh 
pair, from the eighth to the 13th, and 
from the 14th to the 17th (fig. 1). 
1 Numbers of the type specimens of  Lepilemur septen-  
trionalis in the "Catalogue Général, Magasin de Mam- 
mologie et d'ornithologie'' du Museum d'Histoire Natu- 
relle de P aris. : 
L. s. anharanensis: 1974 -no 77 
L. s. sahafarensis: 1974-no 78 
L. s. andrafiamenensis: 1974 -no 79 
425 
426 YVES RUMPLER AND ROLLAND ALBIGNAC 
TABLE 1 
Chromosome number and types in the Lepilemur septentrionalis 
Subspecies 
Number of 
specimens 
examined Chromosomes 
Male Female 2N S A X Y 
L. s. andraf iamaensis  2 2 38 2 34 M A 
L. s. anharanensis 2 2 36 4 30 M A 
Hybrid L. s. anttaranasis  
X L. s. andrafamenensis 1 2 37 3 32 M A 
L. s. sahafarensis 2 1 36 4 30 M A 
L. s. septentrionalis 1 3 34 6 26 M A 
Hybrid L. s. sahafarensis 
x L. s. septentrionalis 2 5 35 5 28 M A 
e c 
.P 
II 9- II - .  
Fig. 1 Karyotype of Lepilemur s. andrafiamen- 
ensis (2N = 38). Note the single pair of small, 
submetacentric chromosomes and the existence of 
satellites on the distal extremities of the fourth 
pair of acrocentric chromosomes (arrow). 
" .., * . .  I .  
The second karyotype, 2N = 36, con- 
sists of two pairs of submetacentric chro- 
mosomes, one of which is similar to the 
aforementioned pair in the first karyotype 
and the other is larger, 15 pairs of acro- 
centric chromosomes, and one pair of sex 
chromosomes in which the X is also a 
metacentric of medium size. The fourth 
pair of acrocentrics has a satellite on the 
distal extremities. The acrocentric chro- 
mosomes regularly decrease in size from 
the first to the sixth pair, from the sev- 
enth to the 12th pair, and from the 13th 
to the 15th pair (fig. 2). 
The third karyotype, 2N = 37, consists 
of three submetacentric chromosomes, 15 
pairs of acrocentric chromosomes, two un- 
paired acrocentric chromosomes, and one 
pair of sex chromosomes, X and Y, similar 
- - .  
t . '  
C) 
88 Jr 
I 
, 
, 
I 
8 
- I  
Fig. 2 Karyotype of Lepilemur s. ankaranen- 
sis (2N = 36). Note one pair of supplementary 
large submetacentric chromosomes and the lack 
of a pair of large and a pair of small acrocentric 
chromosomes. The fourth pair of acrocentric chro- 
mosomes has satellites on its distal extremities 
(arrow). 
to those existing in the karyotype 2N = 
36. Among the submetacentric chromo- 
somes is one pair of chromosomes similar 
to the only pair which exists in the first 
karyotype (2N = 38) and one isolated 
chromosome similar to the chromosomes 
found in the second karyotype (2N = 36) 
(fig. 3). Among the two unpaired acrocen- 
tric chromosomes one is a large chromo- 
some similar to the chromosomes in the 
seventh pair and the other is a small chro- 
mosome similar to the chromosomes in the 
15th pair that are found in the karyotype 
2N = 38. 
The fourth karyotype, 2N = 36, con- 
tains two pairs of submetacentric chromo- 
somes of medium size: one is similar to 
the smallest submetacentric pair existing 
e. 
CHROMOSOMAL VARIABILITY IN LEPILEMUR 427 
'Mo.. 
I 
Fig. 3 Karyotype of a natural hybrid, 2N = 
37. The satellites are clearly visible on the long 
arms of the fourth pair of acrocentric chromosomes 
(arrow). Note one submetacentric and two acro- 
centric chromosomes each of which is unpaired. 
1 
t 
Fig. 4 Karotype of Lepilemur s. sahafarensis 
(2N = 36). Note two pairs of submetacentric 
chromosomes, the smallest similar to those of 
L. s. andra5amenensis and L. s. ankaranensis. 
The satellites are particularly visible on the long 
arms of the fourth pair of acrocentric chromosomes 
(arrow). 
in the two karyotypes, 2N = 38 and 2N = 
36, previously described, 15 pairs of acro- 
centric chromosomes, and one pair of sex 
chromosomes, X and Y, similar to those 
described previously. The fourth pair of 
acrocentrics has a satellite on its distal 
extremities. The acrocentric chromosomes 
regularly decrease in size from the first to 
the seventh pair, from the eighth to the 
12th pair, and from the 13th to the 15th 
The fifth karyotype, 2N = 34, contains 
three pairs of submetacentric chromosomes, 
13 pairs of acrocentric chromosomes, and 
pair (fig. 4). 
Fig. 5 Karyotype of L. s. septentrionalis (2N = 
34). Note the presence of the pairs of submeta- 
centric chromosomes. Two pairs that are found 
also in the L. s. sahafurensis and one pair of large 
supplementary submetacentric chromosomes that 
are found also in  the L. s. ankaranensis. 
- 
Fig. 6 Karyotype of natural hybrid, 2N = 35. 
Note the submetacentric and two acrocentric chro- 
mosomes, each of which is  unpaired. The arrows 
indicate as previously the satellites of the fourth 
pairofacrocentricchromosomes. 
one pair of sex chromosomes, X and Y, sim- 
ilar to those described previously. Among 
the submetacentric chromosomes are two 
pairs of medium size similar to those ex- 
isting in the fourth karyotype, 2N = 36, 
and a large pair similar to the largest 
pair of the second karyotype, 2N = 36. 
The fourth pair of acrocentrics has a sat- 
ellite on the distal extremities. The acro- 
centric chromosomes regularly decrease 
in size from the first to the sixth pair, 
and from the seventh to the 11th pair, 
where the 13th pair is more reduced in 
size and the 14th pair is punctiform (fig. 5). 
The sixth karyotype, 2N = 35, con- 
428 YVES RUMPLER AND 
2. I. rrptm,riona,& tains two pairs of submetacentric chro- 
mosomes of medium size, one unpaired 
submetacentric chromosome, 13 pairs of 
acrocentric chromosomes, two unpaired 
acrocentric chromosomes, and two sex 
chromosomes, X and Y, similar to those 
described previously. Among the unpaired 
chromosomes, the submetacentric of large 
size is similar to those of the largest pair 
of the fifth karyotype. Among the two un- 
paired acrocentric chromosomes the largest 
is similar to those of the seventh pair 
where the smallest is similar to those of 
the 14th pair of the fifth karyotype (fig. 6) 
DISCUSSION 
The results lead us to consider the sys- 
tematics of these animals and their evo- 
lution. 
The existence of these particular karyo- 
types, different from that of the other 
lepilemurs (Rumpler et al., '72; Buettner- 
Janusch et al., '73; Rumpler, in press) led 
us to put this group of Lepilemur into a 
new species: Lepilemur septentrionalis. 
The latest classification did not mention 
a new and particular type in this area of 
Madagascar (Petter and Petter-Rousseaux, 
'60). This proposition, based purely on the 
cytogenetical characteristics, was later 
justified by examination of the skull of 
these animals. In fact, although L. septen- 
trionalis resembles L. dorsalis in size, the 
color of its pelage, and the length of its 
tail to a great extent, it is clearly distinc- 
tive in the shape of its skull which is 
smaller. We await proof of the fertility or 
sterility of the hybrids, 2N = 37, but the 
hybrids 2N = 35 are fertile; in our last 
expedition we caught nine pregnant fe- 
males of which three had a karyotype 
2N = 35. In the absence of noticeable 
morphological differences between L. sep- 
tentrionulis which possess different karyo- 
types, it seems reasonable to consider them 
as subspecies: L. s. andrafiamenensis 
(2N = 38), L. s. anharanensis (2N = 36), 
L. s. sahafarensis (2N = 36), and L. s. 
septentrionalis (2N = 34). This position 
appears to us justified since Lemur fuluzis 
collaris (2N '= 48) and Lemur fuluus ru- 
fus (2N = 60), in spite of their very dissim- 
ilar karyotypes, have given birth to fertile 
hybrids showing that they at least belong 
to the same species (Rumpler, in press). 
2N ~ 3 4  
Chromosomal evolution of the lcp,iemur sepimllionab 
Fig. 7 Design of hypothetical course of chro- 
mosomal evolution of Lepilemur septentrionalis. 
The chromosomal evolution of numer- 
ous lemurs has been by centric fusion, 
especially in the Lemurinae. The compari- 
son of the karyotypes with 2N = 38,2N = 
36, and 2N = 34, where the fundamental 
number is the same, allows us to envisage 
the same phenomenon in Lepilemur. At 
the origin of this evolutionary process is 
the karyotype of L. s. andrafiamenensis 
(2N = 38) which evolved in two different 
ways to give the karyotype of L. s. anka- 
ranensis (2N = 36) and L. s. sahafuren- 
sis (2N = 36) (fig. 7). The transformation 
of the karyotype 2N = 38 to the karyotype 
of L. s. anharunensis (2N = 36) requires 
the centric fusion of two pairs of acrocen- 
tric chromosomes, the seventh and the 
15th pairs. This hypothesis is supported 
by the existence of animals with 2N = 37, 
natural hybrids of the two former ones. 
Evolution from the karyotype 2N = 38 to 
the karyotype 2N = 36 of L. s. sahafuren- 
sis requires the centric fusion of two other 
pairs of acrocentric chromosomes, probably 
the ninth or tenth pair and the 16th pair 
(fig. 7). 
From the karyotype 2N = 36 of L. s. 
sahafarensis karyotype 2N = 34 of L. s. 
septentrionalis arose by centric fusion of 
the same pair of acrocentric chromosomes 
as that which had arisen between the 
karyotypes of L. s. andrafiamenensis (2N 
= 38) and L. s. anharunensis (2N = 361. 
The existence of natural hybrids at 2N = 
35 supports this hypothesis. 
c 
CHROMOSOMAL VARIABILITY IN LEPILEMUR 429 
The distribution of these animals is 
shown on the map of the northern part of 
Madagascar (fig. 8). 
CONCLUSION 
The discovery of a particular karyotype 
in lepilemurs from the north of Madagas- 
car has led us to propose a new species: 
L. septentrionalis. The existence of an im- 
portant chromosomal polymorphism in L. 
septentrionalis and of numerous natural 
hybrids between the different populations 
in the absence of coexisting morphological 
differences indicate a still evolving group. 
**NNoRnao NORD. 
ACKNOWLEDGMENT 
This publication has been supported by 
a grant from the Fondation pour la Re- 
cherche Médicale Française. 
LITERATURE CITED 
Buettner-Janusch, J., A. E. Hamilton and J. A. 
Bergeron 1973 Chromosomes of Lemuriformes. 
I. Chromosome Complement of LepikmUr mus-  
Madagascar of the different subspecies of Lepi- telinus (I. Geoffroy, 1851). Amer. J. Phys. An- 
lemur septatrionalis.  The circled numbers indi- thop., 39: 1-50. 
cate the diploid number of the =im& and the Matthey, R. 1964 Evolution chromosomique et 
place of capture. Blacked areas mean areas with speciation chez les Mus du sous-genre Leggada 
forest. (Gray, 1837). Experientia, 20: 657-665. 
Petter, J. J., and A. Petter-Rousseaux 1960 
Remarques sur la systématique du genre Lepi- 
tween the four subspecies of Lepilemurs, Rumpler, Y. 1970 Etude cytogénétique du Le- 
as in the African mouse Leggada (Mathey, m u r  catta. Cytogenetics, 9: 239-244. 
The significance of chromosomal studies 
'64)' shows that T h e  systematics of the Malagasy lemurs. In: 
tiens can precede Lemur Biology. Tattersall and Sussmann, eds., 
The chromosomal polymorphism observed in press. 
in L. septentrionalis and the great number Rumpler, Y., R. Albignac and N. Rumpler-Ran- 
of hybrids suggest that this group driamonta 1972 Etude cytogenetique de Lepi- lemur ruficaudatus. C. R. Soc. Biol., 166: 1208- 
Fig. 8 Map of distribution in the north of" 
The absence of notable differences be- . lemur. 24: 76-86. 
is still evolving. 1211. 


Intraspécific chromosome variability in a lemur from the North of Madagascar : Lepilemur septentrionalis, species nova

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