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Accepted by S. Carranza: 28 Dec. 2007; published: 18 Feb. 2008
40
ZOOTAXA
ISSN 1175-5326 (print edition)
ISSN 1175-5334 (online edition)
Copyright © 2008 · Magnolia Press
Zootaxa 1705: 40–50 (2008)
www.mapress.com/zootaxa/
A new Nactus gecko (Gekkonidae) and a new Leiolopisma skink (Scincidae)
from La Réunion, Indian Ocean, based on recent fossil remains and
ancient DNA sequence
E. NICHOLAS ARNOLD1 & ROGER BOUR2
1Department of Zoology, Natural History Museum, Cromwell Road, London SW7 5BD, UK E-mail: ena@nhm.ac.uk
2Reptiles et Amphibiens, Systématique et Évolution, Muséum national d’Histoire naturelle, 75005 Paris, France.
E-mail: bour@mnhn.fr
Abstract
Two new lizards from La Réunion island, southwest Indian Ocean, are described on the basis of fragmentary subfossil
material, and their distinctiveness and relationships are confirmed from ancient mitochondrial DNA extracted from these
remains. The gecko Nactus soniae n. sp. is related to N. coindemerensis of Mauritius, while the skink Leiolopisma cecil-
iae n..sp. .has affinities with L. telfairii and L. mauritiana from the same island. As with other La Réunion reptiles
known to date, mitochondrial DNA phylogenies indicate that both the new forms colonized this island from Mauritius.
Molecular clock considerations suggest that colonisations took place over 1My ago and that the new species, together
with Phelsuma day geckos, survived the massive volcanic eruptions that took place on La Réunion 180000-230000
years ago.
Key words: Nactus, Leiolopisma, La Réunion, ancient DNA, cytochrome b, 12S rRNA
Introduction
La Réunion lies some 500km East of Madagascar and is one of the three Mascarene islands, the others being
Mauritius 200km to the northeast of La Réunion, and Rodrigues 900km to the east. La Réunion was colonised
by people only in the second half of the Seventeenth century (Cheke, 1987), but much of its original verte-
brate fauna of reptiles and birds is now extinct. Just three native reptile species survive: the endemic day gec-
kos, Phelsuma borbonica and P. inexpectata (Austin et al., 2004) and the small lygosomine skink
Cryptoblepharus boutonii. A giant tortoise, Cylindraspis indica (possibly including C. borbonica Bour,
1980—see Austin and Arnold, 2001, Austin et al., 2002) occurred perhaps as late as the mid-1800s (Bour,
1981) and a chalcidine skink, Gongylomorphus bojeri borbonicus became extinct around the same time, hav-
ing last been collected in 1839 (Cheke, 1987). A further skink, similar to the lygosomine Leiolopisma telfairii
of Mauritius, has been recorded from recent fragmentary fossil remains, collected by Graham S. Coles in a
cave near St Paul, on the west coast of La Réunion (Arnold, 1980; Cowles, 1987). Here we report more fossils
that provide further information about this skink and also include a night gecko, Nactus, which again turns out
to be similar to Mauritian species. Mitochondrial DNA sequence recovered from the fossils confirm morpho-
logical indications of the generic allocation of the two forms and confirm that they deserve species status
(Austin and Arnold, 2006, unpublished data).
The new material comes from coastal caves near sea level on the west side of La Réunion. Most is from
the Grotte au Sable, south of the town of St-Gilles, and was excavated by R. Bour and F. Moutou (in 1980),
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and later by C. Mourer-Chauviré and R. Mourer (in 1987). Some Leiolopisma bones were found in the most
northeasterly cave among the Grottes des Premiers Français near St Paul by B. Kervazo (in 1974), and R.
Bour (in 1980). Details of these localities are given by Mourer-Chauviré et al. (1999). Apart from Leiolopisma
and Nactus, material from the Grotte au Sable includes Phelsuma (BMNH R16530-16533; Fig. 1) and Gongy-
lomorphus, and the agamid lizard, Calotes versicolor (Daudin, 1802) (BMNH R16568-16575), a species
introduced from Java in the nineteenth century (A. Vinson, 1871). The Calotes bones are less patinated than
the others, suggesting the latter are significantly older. Finally, a small amount of Leiolopisma material was
excavated from a further cave near St Paul by G. S. Cowles (1987).
Abbreviations
bp base pairs.
BMNH Collections of Natural History Museum, London; specimens with numbers prefixed by ‘R’ are in
the Palaeontology Department of that museum, and the others in the Zoology Department.
Results
Family Gekkonidae
Genus Nactus
Nactus soniae n. sp.
Nactus borbonicus (nomen nudum) in Probst (1997: 144), and in Probst and Brial (2002:24).
Etymology. Named after Sonia Ribes-Beaudemoulin, present curator of the Muséum d’Histoire Naturelle,
Saint-Denis, La Réunion. She organised a dozen expeditions to collect important subfossil remains of verte-
brates, especially tortoises, birds and bats from the marshes of l’Ermitage near St-Gilles.
Distribution. Known only from La Réunion, southwest Indian Ocean.
Material (Figs 2–3). Holotype: Grotte au Sable, St-Gilles, La Réunion; frontal bone; BMNH R16534.
Paratypes: Grotte au Sable, St-Gilles, La Réunion; 1 frontal, 1 maxilla, 1 dentary; BMNH R16535-16537.
DNA sequence. Grotte au Sable, St-Gilles, La Réunion. 681 base pairs (bp) of mitochondrial DNA
sequence extracted from a frontal bone, comprising 305 bp of cytochrome and 374 bp of 12S rRNA genes (J.
J. Austin and E. N. Arnold, unpublished data).
Diagnosis. A small Nactus, estimated from available bones to be about 45mm from snout to vent. Frontal
not elongate, with only weakly developed anterior lateral submaxillary flanges. Maxilla with dorsal lamina
inset medially, so outer surface of tooth-bearing body of bone is rounded; its posterior section comparatively
short. Tooth counts low with 29 teeth in maxilla and 24 in dentary of available material. Also has distinctive
mitochondrial DNA sequence (12S rRNA and cytochrome b).
Differs from other Nactus in conformation of maxilla and from other Mascarene species in the following
additional features: N. serpensinsula and N. durrelli of Mauritius—smaller size and lower tooth counts; N.
coindemerensis of Mauritius—larger size; two undescribed subfossil species from Rodrigues (E. N. Arnold, J.
J. Austin and C. G. Jones, unpublished observations)—lower tooth counts, only weakly developed anterior lat-
eral submaxillary flanges on frontal bone, also lacking the elongation of the frontal found in one of the Rod-
rigues species. Distinguished from sympatric Phelsuma geckos (Fig. 1) by much narrower frontal bone with a
longer tubular section, a higher dorsal lamina on the maxilla and coarser dentition.
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FIGURE 1. Phelsuma sp., material from Grotte au Sable, St-Gilles, La Réunion. Above: frontals (dorsal and ventral
views). Below: left maxilla (medial view). Scale in mm.
Description. Available material is very fragmentary with only three skull elements represented. Frontal
somewhat expanded anteriorly, and strongly expanded posteriorly, with an intervening narrow waist between
the orbits. The tubular section of the frontal is relatively long and the sides of the expanded posterior section
of the bone are thickened below. Dorsal surface slightly but distinctly concave, with a depressed anterior facet
or facets that would lie under the prefrontals in a complete skull. The shape of the anterior border of the sub-
dermal surface of the frontal, bordering this facet posteriorly is convex anteriorly with a pointed projection on
each side. Small lateral flanges are visible on the frontal anteriorly which would lie under the posterior dorsal
projection of the lamina of each maxilla. The three N. soniae frontals examined (including one sacrificed dur-
ing DNA extraction) show considerable variation in form, including how broad they are, the shape of the ante-
rior border of the dermal surface which is convex and pointed in the holotype but more gently rounded in the
others, and the precise size of the small anterior lateral flanges. The lateral borders of the frontal anterior to its
narrow waist may also be rather wavy.
Maxilla generally similar to other Nactus, especially N. serpensinsula, with a high dorsal lamina that rises
to an acute point posteriorly, where it contacts the frontal, overlapping its anterior lateral flange. A row of four
foramina in a horizontal line on the lateral surface of the tooth-bearing body of the bone and two more where
the body and the dorsal lamina join. Differs from N. serpensinsula and other Nactus in the dorsal lamina being
inset medially on the tooth-bearing body of the maxilla so, in transverse section, the outer face of this is
rounded before the lamina rises. The body of the maxilla posterior to the lamina is relatively short. There are
24 teeth, a similar count to that found in Mauritian N. coindemerensis which has about 26, but considerably
lower than those in N. serpensinsula and N. durrelli which have about 36–38 teeth in adults.
Dentary is similar to that of most other Nactus species, being rather slender, with a short ventral groove at
the anterior extremity; six foramina in a roughly horizontal line on lateral surface which has a tridentate poste-
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rior border, medial surface with a depressed splenial scar and a V-shaped posterior border in which the upper
edge has a pronounced step. The bone, which is from a relatively small individual, has 29 teeth, a count again
similar to that found in Mauritian N. coindemerensis, but considerably lower than those in N. serpensinsula
and N. durrelli which have about 39–40 teeth in adults.
The size of the frontals, the elements apparently from the largest individuals represented in the available
sample, indicate that N. soniae was around 45mm from snout to vent. It is consequently intermediate in size
between N. coindemerensis of Mauritius, which grows to about 36mm from snout to vent, and N. serpensin-
sula and N. durrelli from the same island which reach at least 67mm and 55mm (Arnold and Jones, 1994).
Relationships. DNA confirms that N. soniae is a Nactus and indicates it is most closely related to the
diminutive N. coindemerensis of Mauritius (J. J. Austin and E. N. Arnold, unpublished data), something also
supported by its relatively small size and low tooth counts.
Family Scincidae
Genus Leiolopisma
Leiolopisma ceciliae n. sp.
Etymology. Named after Cécile Mourer-Chauviré, celebrated specialist on fossil birds, who took part in exca-
vations for subfossil remains on La Réunion between 1987 to 2001, identifying half a dozen of new species of
birds. She also proposed the hypothesis of a ‘great extinction’ on the island, associated with cataclysmic vol-
canic eruptions, 180,000–230,000 years ago (Mourer-Chauviré et al., 1999).
Distribution. Known only from La Réunion, southwest Indian Ocean.
Material (Figs 4–6). Holotype: Grotte au Sable, St-Gilles, La Réunion; right dentary; BMNH R16538.
Paratypes: Grotte au Sable, St-Gilles, La Réunion; 1 juvenile frontal, 1 fused postorbital and postfrontal, 2
right maxillae*, 2 quadrates*, 1 left pterygoid, 4 left and 5 right dentaries*, 2 right posterior mandibles*, 6
presacral vertebrae*, 3 left and 3 right humeri*, 1 sacrum, 2 left and 3 right pelves*, 1 left and 1 right fem-
ora*, 1 right tibia; BMNH R16539-16564. Grottes des Premiers Français , St-Paul, La Réunion ; 1 right quad-
rate, 1 right posterior mandible, 1 right humerus; BMNH 16565-16567. Cave near St-Paul, La Réunion; 1
right dentary, 1 partial right humerus, 1 right tibia; BMNH 1977.881-883 (material previously reported and
tibia illustrated by Arnold, 1980).
Most paratype material of Leiolopisma ceciliae is deposited in the reptile collection of the Department of
Palaeontology, Natural History Museum, London. An asterisk indicates that examples of the elements con-
cerned have also been placed in the Muséum d’Histoire Naturelle, St-Denis, La Réunion.
DNA sequence. Grotte au Sable, St-Gilles, La Réunion. 683 bp of mitochondrial DNA sequence extracted
from a left dentary, comprising 307 bp of cytochrome b and 376 bp of 12S rRNA genes (Austin and Arnold,
2006—GenBank accession numbers: AY 818748, AY 818818).
Diagnosis. A Leiolopisma intermediate in adult size and robustness between the two Mauritian species of
the genus, L. telfairii and the giant L. mauritiana. Most similar to L. telfairii but differs in larger maximum
size, coarser dentition, frontal bone narrower anteriorly at least in young animals, the fused postorbital and
postfrontal bones with shorter posterior section and less prominent lateral spur, and quadrate more expanded
lateromedially. L. mauritiana grows much larger than L. ceciliae and has coarser dentition. L. ceciliae is
also separated from L. telfairii and L. mauritiana by distinctive mitochondrial DNA sequence (12S rRNA and
cytochrome b gene fragments).
Fossil remains distinguished from those of the sympatric skink Gongylomorphus bojerii borbonicus by
larger size, fused frontal bones and absence of a Meckel’s groove in the dentary.
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FIGURE 2a, 2b. Nactus soniae n. sp., material from Grotte au Sable, St-Gilles, La Réunion. a. Holotype. Frontal bone
(dorsal and ventral views). Scale in mm. b. Paratypes. Left maxilla and right dentary (lateral views). Scales in mm.
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FIGURE 2. Nactus soniae n. sp., material from Grotte au Sable, St-Gilles, La Réunion. c. Paratypes. Left maxilla and
right dentary (medial views). Scales in mm.
Description. Available material is fragmentary, but seven cranial and six postcranial elements are repre-
sented. Comparison with material of living L.telfairii indicates a maximum snout-vent length of at least
175mm. Frontal bones fused from an early stage of development as in other lygosomine skinks, narrower
anteriorly than in L. telfairii at least in young animals. Fused postfrontal and postorbital bones with a shorter
posterior section than in L. telfairii and with a less prominent lateral spur that is less obviously directed for-
wards. Dentaries with a closed Meckel’s groove and sometimes more robust than in equivalent sized
L. telfairii from mainland of Mauritius (described by Arnold, 1980), but less so than in L. mauritiana; about
six foramina in a horizontal line on anterior lateral surface. Dentition of maxillae and dentary bones coarser
than in equivalent-sized L. telfairii and finer than in L. mauritiana: this is reflected in differences in tooth
number for animals of similar size (Fig. 7) and in robustness of the teeth. Quadrate more expanded laterome-
dially than in L. telfairii and tibia with a more prominent lower tubercle.
Distinctive features of type. Robust dentary originally with 25 teeth (numbers 2,3,4,9,14 and 22 miss-
ing), the last three teeth decreasing in size; a roughly horizontal line of six foramina present on the anterior lat-
eral surface of the bone.
DNA sequence. DNA of L. ceciliae differs from equivalent regions of the genome of living L. telfairii
from Round island, north of Mauritius, in 39 nucleotide substitutions (5.7% of uncorrected divergence), and
from L. mauritiana by 29 nucleotide substitutions (4.2% uncorrected divergence) – Austin and Arnold (2006).
Relationships. A phylogeny of 42 species of skinks based on mitochondrial DNA associates L. ceciliae
with the other two species of Leiolopisma, corroborating the clade status of this genus (Austin and Arnold,
2006). DNA sequence confirms that Leiolopisma is part of the Lygosominae, something also supported by its
fused frontal bones, and within this subfamily belongs to the Eugongylus group of genera. It also indicates
that, of the two Mauritian species in the genus, L. ceciliae may be more closely related to the giant L. mauriti-
ana, rather than to the morphologically more similar L. telfairii (Austin and Arnold, 2006).
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FIGURE 3. Nactus soniae n. sp. Scanning electron microscope photograph of holotype frontal bone (dorsal view).
Discussion
Neither Nactus soniae nor Leiolopisma ceciliae is presently known to exist on La Réunion and both are pre-
sumed to be extinct. Nor were they reported during the more than 300 years since human colonization of La
Réunion took place. This is perhaps not surprising in the case of the Nactus which may have been inconspicu-
ous, being small and probably nocturnal like its congeners (Arnold and Jones, 1994). But the large Leiolo-
pisma would surely have attracted comment if it had been seen. Père Brown, a mythical writer for many
historians, whose supposed writings perhaps date from the early Eighteenth century (Cheke, 1987), mentioned
large lizards in the southern part of La Réunion that were claimed to grow to a foot and a half long (a total
length of around 450mm). But Brown also wrote (possibly from secondhand information) that they were arbo-
real, bright and varied in colour, and had a flattened head that was pierced in the middle (perhaps referring to
the way light can pass through one transluscent ear drum of a gekkonid lizard and across the pharynx to be
discernible through the ear drum on the other side). These are all features found in Phelsuma day geckos
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FIGURE 4. Leiolopisma ceciliae n. sp., material from Grotte au Sable, St-Gilles, La Réunion. Holotype. Dentary (lat-
eral and medial views). Scale in mm.
FIGURE 5. Leiolopisma ceciliae n. sp., material from Grotte au Sable, St-Gilles, La Réunion. Selected paratypes, from
individuals of various sizes. Top row: left mandible (lateral view), right maxilla (lateral view), fused left postfrontal and
postorbital bone (dorsal view), left quadrate (posterior view). Middle row: right dentary (medial view), posterior left
mandible (lateral view). Bottom row: Left humerus, left pelvis (lateral view), sacrum (dorsal view), presacral vertebrae
(lateral and ventral views), right femur, tibia. Scale in mm.
rather than skinks, although there is no other evidence that ones of such size occurred on La Réunion. There
were also no eyewitness reports of two species of Leiolopisma on the mainland of Mauritius. It has been sug-
gested in these cases, this was because the skinks had been exterminated by rats from shipwrecks that reached
Mauritius before people actually settled there (Cheke, 1987). This may also have applied to La Réunion,
although the dates rats were first noticed there are relatively well known: about 1670 for the ship rat, Rattus
rattus, and 1750 for the common rat, Rattus norvegicus (Moutou, 1980).
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FIGURE 6. Leiolopisma ceciliae n. sp., material from Grotte au Sable, St-Gilles, La Réunion. Paratype. Frontal of juve-
nile animal (ventral and dorsal views, anterior upwards). Scale in mm.
With the exception of bolyerine snakes, La Réunion has representatives of all the naturally occurring rep-
tile groups on Mauritius, namely Cylindraspis tortoises, Phelsuma and Nactus geckos, and Leiolopisma and
Gongylomorphus skinks. DNA phylogenies indicate that the giant tortoise (Cylindraspis indica) and the two
day geckos (Phelsuma borbonica and P. inexpectata) reached La Réunion from that island (Austin & Arnold,
2001, Austin et al., 2004), and the same is likely to be true for Leiolopisma ceciliae (Austin & Arnold, 2006)
and Nactus soniae. While Mauritius originally had 19 species and subspecies of reptiles (Arnold, 2000), La
Réunion apparently possessed just seven, in spite of its larger size (2510km2 compared with 1865km2) and its
much more varied geography. This may partly be because groups on Mauritius have all undergone speciation
within the island, while this does not appear to be so for La Réunion. This is a relatively young island, its old-
est rocks being only 2.1My (McDougall, 1971) compared with about 8My for Mauritius (McDougall and
Chamaloun, 1969). However, molecular clocks indicate that the lizards at least have been present on La
Réunion for a long time, at least a million years, in the case of the Phelsuma and perhaps longer for the Leiol-
opisma (Austin et al., 2004, Austin and Arnold, 2006). Like many birds (Mourer-Chauviré et al., 1999), these
forms must have survived the massive eruptions that occurred on the island 180,000–230,000 years ago (Aus-
tin and Arnold, 2004).
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FIGURE 7. Variation in number of teeth with size of maxillae (above) and dentary bones (below) in different species of
the Mascarene skink genus Leiolopisma. Stars: L. ceciliae n. sp. from La Réunion. Assemblage to left: L. telfairii from
Mauritius (triangles: living animals from Round Island, dots: subfossil material from mainland of Mauritius). Assem-
blage to right: subfossil L. mauritiana from mainland of Mauritius. Some symbols indicate more than one specimen.
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Acknowledgements
We thank G. S. Cowles, B. Kervazo, C. Mourer-Chauviré, F. Moutou and S. Ribes-Beaudemoulin for material
or aid in its collection. J. J. Austin conducted the DNA extractions and analyses mentioned in this paper, N. P.
B. Arnold provided technical help and P. Hurst took the photographs of specimens.
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