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Post by sebbe67 on Jun 19, 2008 13:54:56 GMT
A new species of giant gecko of the genus Tarentola (Reptilia: Squamata: Gekkonidae) from Jamaica
J. Zool., Lond. (1998), 1998 The Zoological Society of London.
The herpetological collections of the National Museums of Scotland comprise approximately 5000 lots. Among material discovered during recent recuration and cataloguing of the collection (Sprackland & Swinney, In press) is a jar containing a single specimen of a large gecko, of a previously undescribed taxon. The specimen is registered as NMSZ 1884.23.7 and forms part of a small batch of zoological specimens from Jamaica donated to the collection, in 1884, by a Miss Cooper of Kingston,
Jamaica. (At that time the collection formed part of the´Edinburgh Museum of Science and Art, see Herman, McGowan & Swinney, 1990.)
The extant herpetofauna of Jamaica includes only nine species of geckos; seven in the genus Sphaerodactylus and one each in Aristelliger and Gonatodes (Schwartz & Henderson, 1985, 1988; Lambert, 1986). The largest species is Aristelliger praesignis Hallowell, 1857, a moderate-sized lizard, males of which may reach about 85 mm snout to vent length (SVL). The remaining species are small, none growing to more than about 40
mm SVL (Schwartz & Henderson, 1991). The new lizard is readily assigned to the predominantly African genus Tarentola because of its heavily
tuberculated lepidosis and the possession of claws only on the third and fourth digits, features that distinguish Tarentola from the American endemic Aristelliger (see `Discussion') (Boulenger, 1885; Schwartz & Henderson, 1985). This new Tarentola is most similar to the members of the subgenus Sahelogecko of Joger (1984a), in particular T. annularis. However, the specimen differs from all described species in the genus in features of scale structure and distribution, snout shape, and size. It is described here as a new species.
METHODS
Measurements were made using dial callipers and rounded down to the nearest 0.5 mm. The nomenclature for describing characters and the techniques for collecting meristic data follow Joger (1984b). In examining
dentition, both teeth and open tooth sockets were counted. Sex was confirmed by x-ray examination (i.e. lack of cloacal bones).
DESCRIPTION
Tarentola albertschwartzi sp. nov. Holotype: NMSZ 1884.23.7, adult female, `Jamaica', presented by Miss Cooper, Kingston, in 1884.
Diagnosis: A large gecko with distinctive enlarged tubercles arranged in well-de®ned rows on the dorsolateral and lateral surface of the body (Fig. 1a & b), the outline formed by the most ventral of which forms a denticulate margin in which the spaces between tubercles
are not visible (Fig. 1c). Such a row, in which there are tubercles but no intervening longitudinal skin, is absent in other Tarentola species. A unique, distinct row of enlarged, denticulate scales extending from the posterior border of the lower jaw to the gular region is also
clearly seen from below. The specimen is further distinguished from most other species of Tarentola by its large adult size, and from Tarentola mauritanica by the huge pointed tubercles in distinct longitudinal rows
along the sides. In T. mauritanica, the tubercles are arranged in closely-packed transverse series, and are subequal in size from vertebral to lateral rows, while T. albertschwartzi has only three greatly enlarged scale
rows along the sides, with the dorsal tubercles much smaller than the laterals. From T. annularis, the new species is diagnosed by its conspicuously larger gular scales, more pointed dorsolateral tubercles, and larger caudal tubercles. Description of type: Head broad, with blunt snout
and greatly expanded temporal region (Fig. 2). Snout longer (14 mm) than distance between eye and ear (10 mm). Head scales small, round, and rugose. Supraoculars slightly keeled, twice as large as interoculars. Nostril in a single nasal, larger than supralabials, with the dorsolateral process overhanging the nostril, producing a feeble crest with a small anterior horn. Ear opening with small conical scales that barely project into the ori®ce. Mental longer than broad. Back and sides covered with small, round smooth scales (of the sort termed `interstitial paving scales' by Schwartz [1968]). Mid-dorsal line marked by an irregular row of small tubercles. Either side of mid-line series dorsum covered with irregularly arranged large tubercles, interspersed with smaller tubercles about half their diameter. Lateral to these irregularly arranged tubercles are three rows of even larger tubercles resembling stout, blunt thorns, each surrounded by a rosette of 8±10 smaller tubercles. Dorsal-most row (row 1) contains 22 tubercles between the nape and ®rst caudal annulus. The tubercles of all three rows are further aligned in vertical series along raised folds of skin. Scattered non-rosetted tubercles between regularly
arranged series. Two further rows of smaller, rosetted tubercles between rows 1 and 2. Small tubercles, lacking rosettes or with surrounding scales only slightly larger than the paving scales, arranged in an irregular double
row between rows 2 and 3. Tip of each thorn-like tubercle displaced posteriorly. Tubercles weakly keeled anterior to their tips. In row 1,
keels aligned with the long axis of the body. Keels of tubercles of rows 2 and 3 somewhat oblique. A series of enlarged tubercles, more triangular in
shape than the body series, extending from the angle of the mouth to the lateral gular region. Pronounced gular and postmental fold de®nes a concave gular area. The ventral scales hexagonal, small, and smooth.
Inguinal similarly shaped, but twice as large as ventrals. Gulars extremely small and granular. Tail similar to that of T. annularis but with more pronounced tubercles. Tubercles strongly keeled, arranged in whorls of eight. Tail of holotype regenerated posterior to third annulus.
Limbs pentadactyl, the ®rst digit reduced. Substantial claws present only on the third and fourth digits of each limb, the other three digits of the hind limb bear sessile micro claws. Subdigital lamellae undivided, 17 under
the ®rst toe, 21 lamellae under the fourth. Measurements (mm): SVL, 137; tail (regenerated), 97; forelimb, 42; hind limb, 50; length of head, 39; width
across temples, 28; length of maxilla, 18.5. Counts: interorbitals, 11; supraocular rows, 6; upper labials, 11; lower labials, 10; teeth in upper jaw, 82 teeth (40 on the left, 42 on the right); teeth in lower jaw, 77
(39 on the left, 38 on the right). Colour in alcohol: pale greyish-tan, with no signs of dorsal markings. Ventrally lighter, egg-shell white. Comments: The collection locality is known no more precisely than `Jamaica'. The specimen is bleached but is otherwise in good condition. There are two raggededged holes through the neck, almost certainly made so as to suspend the specimen inside a jar for ®xation and/ or display. Etymology: The species is named for Albert Schwartz (1923±1992) whose decades of study of the West Indies`left behind a herpetological legacy for a single geographic region that is unlikely ever to be duplicated. We can only stand in awe of what he accomplished . . .'(Duellman, Thomas & Henderson, 1993).
DISCUSSION
Although the currently known geckos of Jamaica are all
small to moderate species, there is evidence that a large
species of gecko formerly inhabited the island. Hecht
(1951) describes a fossil giant gecko, Aristelliger titan
from bones discovered in Pleistocene or sub-Recent
deposits in three Jamaican caves. He speculated that the
gecko remains had accumulated in the caves as a result
of the hunting activity of barn owls (Tyto alba Scopoli)
and/or possibly a now-extinct larger owl (Hecht, 1952).
Based on the sizes of the bones recovered and comparison
with those of extant Aristelliger species he
estimated that A. titan reached a SVL of about 160 mm.
The fossil evidence indicates that A. titan lived on
Jamaica before, and for a short time concurrently with,
A. praesignis (Hecht, 1952).
Hecht's assignment of the fossil to Aristelliger is
somewhat tentative (see his comments about ambiguous
skeletal characters of Cuban material intermediate
between Aristelliger and Tarentola [Hecht, 1951: 2]). It
is based partly on the fact that, of the gekkonid genera
with amphicoelous vertebral centra known (at the time)
from the Greater Antilles (Aristelliger, Hemidactylus
and Tarentola), only Aristelliger was extant on Jamaica.
The similarity of skeletal characters of the genera
Tarentola and Aristelliger raises questions about
Hecht's generic assignment of A. titan. External morphological
characters, particularly features of lepidosis,
readily distinguish the two genera but no such distinct
skeletal characters have been determined to distinguish
them. Therefore, we must consider the possibility that
Hecht's fossil giant gecko might actually belong to the genus Tarentola and that the present specimen represents
a population of A. titan (actually Tarentola titan)
which survived on Jamaica at least into the late nineteenth
century. In this context it is pertinent to note that
elsewhere in the West Indies Tarentola americana Gray,
1831 is often found living in caves (Schwartz & Ogren,
1956; Schwartz & Henderson, 1991). The lack of directly
comparable material makes comparison of extant and
fossil taxa particularly challenging. However, some
authors (Etheridge, 1965; Schwartz & Henderson, 1988)
consider A. titan a junior synonym of A. lar Cope 1862,
a giant extant gecko (growing to 135 mm SVL), which
in its present-day distribution is endemic to Hispaniola
(Cochran, 1941; Schwartz & Henderson, 1988, 1991).
The presence of well-developed body tubercles and of
claws on only two digits, clearly allies our specimen with
Tarentola. Barring further evidence from fossils, we take
the view that Hecht correctly assigned titan to Aristelliger
and thus that it is distinct from T. albertschwartzi.
Therefore, we conclude that Jamaica was formerly
inhabited by two species of giant gecko, though not
necessarily contemporaneously. A single species of Tarentola
has been recorded previously in the West Indies.
Tarentola americana has two recognized subspecies;
one, T. a. americana, occurs on Cuba and surrounding
keys, the other, T. a. warreni Schwartz, 1968, inhabits
islands of the Bahamas (Schwartz, 1968; Schwartz &
Henderson, 1991). All the other members of the genus
inhabit either north Africa, southern Europe, or the
subtropical islands of the eastern Atlantic (Joger,
1984a, b; Kluge, 1993; Welch, 1994). Schwartz (1968)
suggested that T. a. americana is not a human introduction
but that it has been long established on Cuba. This
suggestion is supported by morphological features that
so distinguish the New World species from its African
cogeners that Joger (1984a, b) assigned the former to its
own subgenus, Neotarentola. (Some authors do not
recognize Joger's subspecies on the grounds that type
species were not designated for each of the subgenera
created [BoÈhme, pers. comm.]). Schwartz (1968) presented
two alternative hypotheses to account for the
Caribbean distribution of T. americana: 1) that T. a.
warreni is a relatively recent, Pleistocene or post-Pleistocene,
immigrant into the Bahamas from Cuba; and 2)
that it is part of a more ancient, possibly Pliocene,
Bahamian relict fauna, which has persisted on, and
radiated out from, a refuge on one or more of the
volcanic islands of the outer Great Bank. The discovery
of a second Caribbean species, T. albertschwartzi, shows
that the genus formerly had a wider distribution than
previously recognized.
The existence of only a single specimen of T. albertschwartzi
and the lack of any precise collection locality
data, raises the possibility that the specimen is not a true
part of the Jamaican fauna but that it was imported into
the island. The Gekkonidae include several highly
successful tramp species and it is possible that this
specimen was itself a tramp. However, it shows no
distinct af®nities with any currently recognized species
(Grandison, 1961; Schwartz, 1968; Joger, 1984a, b), though it is generally more similar to the north African
species than it is to the New World T. americana
(Boulenger, 1893; Loveridge, 1944; Schwartz, 1968;
Schwartz & Henderson, 1985, 1991). The presence of
distinct rosettes surrounding the tubercles of the dorsolateral
and lateral rows resembles the condition in the
subgenus Tarentola (Joger, 1984b). In T. albertschwartzi,
the rosettes completely surround the central tubercle,
while in the species of the nominate subgenus they form
a horseshoe or oblique oval around the central tubercle.
Tarentola albertschwartzi has slightly more subdigital
lamellae (21 vs. 12±20) than the subgenus Tarentola,
while it has much smaller conical scales along the border
of the ear than does T. americana. It is further distinguished
from T. americana by the number of tail whorls
(8 in T. albertschwartzi versus 10±14 in T. americana)
and by the presence of rosettes around the dorso-lateral
tubercles (absent in T. americana). The large size and
conspicuous nature of the lower lateral (i.e. those of
row 3) and gular tubercles in T. albertschwartzi, as
viewed ventrally, is unique in the genus. In general
form, T. albertschwartzi most closely resembles the
African T. annularis from which it is distinguished by its
three rows of greatly enlarged dorso-lateral tubercles
and the row of prominent gular tubercles.
Data from other specimens donated by Miss Cooper
do little to help resolve the origins of the specimen. She is
recorded as having donated only two batches of specimens
to the Museum, both in 1884. In addition to the
batch of spirit-preserved specimens she donated a sample
of ``Alligator leather from Jamaica''. This latter specimen
is presumed to be skin from Crocodylus acutus Cuvier,
1807, as this species is commonly called the `alligator' in
Jamaica (Grant, 1940). It was registered in the Industrial
Department of the Museum as NMSA 1884.32 but was
subsequently de-accessioned and sold in October 1940
(see Minute Book, Disposals Board [Royal Scottish
Museum]. Vol. 1. p. 272 ± manuscript in the archives of
the NationalMuseums of Scotland). For both donations
the register entries merely note the specimens as
``presented by Miss Cooper, Kingston, Jamaica''.
Unfortunately, other than the gecko, only four of the
spirit-preserved specimens can now be traced with certainty.
Two are a hatching and embryo American
crocodile, Crocodylus acutus (NMSZ 1884.23.1), the
third is a vial containing insect larvae (NMSZ
1884.23.4), and the fourth is a specimen of Typhlops
jamaicensis Shaw, 1802 (NMSZ 1884.23.8). The remaining
untraceable specimens are listed as: a lizard
and batrachians (NMSZ 1884.23.2), caterpillars (NMSZ
1884.23.3), crustaceans (NMSZ 1884.23.5, noted as
destroyed in June 1941), and scorpions (NMSZ
1884.23.6). Only Typhlops jamaicensis is endemic to
Jamaica, so these data do little to help specify the
collecting locality. Attempts to try to discern the collection
locality of the giant gecko by tracing details of the
identity ofMiss Cooper have proved inconclusive.
It may seem unusual that a lizard as large as
T. albertschwartzi could have survived unreported until
at least into the last quarter of the nineteenth century. Hans Sloane, who lived on Jamaica from December
1687 until March 1689 and collected extensively, apparently
made no mention of a giant gecko (Clutton-Brock,
1994). This might suggest that this gecko was restricted
to particularly remote or inaccessible areas possibly
because, even by the late seventeenth century, its habitat
had been substantially lost due to clearance of native
vegetation early in the history of the agricultural development
of the island (Gosse & Hill, 1851; Lack, 1976).
Within a restricted range its populations may have been
particularly vulnerable to the impact of introduced
predators. Rats, which arrived in Jamaica with European
colonists, subsequently had a major impact on the
island's economy. In the late eighteenth century, they
were responsible for the loss of up to an estimated 25%
of the sugar-cane crop. In an attempt to reduce the
rodent populations larger predators, such as the
domestic cat, the marine toad, Bufo marinus (L.) and the
small Indian mongoose, Herpestes auropunctatus
Hodgeson, were introduced (Lever, 1994). The latter
species, which rapidly became established over much of
the island following its importation from Asia in 1872,
had a particularly devastating impact on the native
fauna, especially the herpetofauna (Hoagland, Horst &
Kilpatrick, 1989; Lever, 1994).
It is not unknown for a large representative of a taxon
consisting predominantly of small species, living on
reasonably-well explored islands, to remain unknown
except as museum specimens. For example, the largest
known gecko Hoplodactylus delcourti Bauer and
Russell, 1986, was discovered in the Marseilles Museum
in 1985 (Bauer & Russell, 1986) and is presumed to be
from New Zealand. Despite subsequent searches in New
Zealand and various museum collections, H. delcourti
remains known only from the holotype.
We also note that the largest member of the iguanid
genus Cyclura, which grows to 1300 mm, was considered
to be extinct for several decades (Woodley, 1980),
until its rediscovery on Jamaica in 1989 (Hudson, 1994).
Cyclura collei Gray, 1845 is now being propagated in
zoological parks, and efforts are being made to restore
its habitat and repopulate reserve areas with captiveproduced
iguanas (Alberts, 1993). If so large a species as
the Jamaican iguana could escape observation for so
long, we wonder if the hitherto unknown Jamaican
giant gecko might also eventually be discovered alive in
the wild.
Acknowledgements
We gratefully acknowledge Drs Wolfgang BoÈhme and
Aaron Bauer for criticism of drafts of the manuscript,
Leslie Florence and Dr Katherine Eremin (National
Museums of Scotland) for photography and x-ray
plates, Emma Robinson, Andy Whittington, Jim Macdonald
(National Museums of Scotland), Margaret
Acton (Centre for the Study of Christianity in the Non-
Western World, University of Edinburgh) and the
Jamaican High Commission, London for logistical support. Drs Colin McCarthy, Garth Underwood
(Natural History Museum, London) and George Zug
(U.S. National Museum of Natural History) provided
information on Tarentola specimens in their care, and
Drs Underwood and Bauer shared information about
fossil Jamaican geckos.
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78 R. G. Sprackland and G. N. Swinney
Source: A new species of giant gecko of the genus Tarentola (Reptilia: Squamata: Gekkonidae) from Jamaica
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