Unravelling the underestimated diversity of Philippine water monitor lizards (Squamata: Varanus salvator complex), with the description of two new species and a new subspecies
Author
Koch, André
Author
Gaulke, Maren
Author
Böhme, Wolfgang
text
Zootaxa
2010
2446
1
54
journal article
10.5281/zenodo.195067
35cdc20a-5cad-44f7-9f7a-f706d7dace29
1175-5326
195067
Varanus cumingi
Martin, 1838
Figures 4–14
Synonymy.
No synonyms of this
Philippine
monitor species are known (
Böhme 2003
).
Diagnosis.
The diagnosis following the arguments by
Gaulke (1992a)
and
Koch
et al.
(2007)
was modified only with respect to scalation features due to the enlarged data set for this study. As a conspicuous member of the
V. salvator
complex,
V. c u m i n g i
can be identified by two main features: (1) the intensive yellow colour pattern of head and body in combination with the black background colour; (2) possessing enlarged occipital scales around the pineal organ (character P = 46–57, mean = 49.89); (3) enlarged dorsal scales (characters X = 21–33, mean = 27.79; Y = 86–103, mean = 92.63; and XY = 114–136, mean = 120.42); and (4) low scale counts around the tail at one third of the tail length (character R = 42–55, mean = 47.57). Additional characteristics of the colour pattern of
V. cumingi
are (5) more-or-less distinct longitudinal black ocelli on the ventral side of the tail; (6) a pronounced black streak extending from the eye to the upper margin of the tympanum; (7) usually a unicoloured yellow chin without dark bars or crossbands; and (8) eight to fifteen dark lateral bars or crossbands on the belly.
FIGURE 4.
V. c. cumingi
from west Mindanao showing the typical dorsal colour pattern of indistinctive yellow transverse bands, an interrupted medio-dorsal stripe, and a predominantly yellow head with few dark markings. Photo by Maren Gaulke.
FIGURE 5.
Dorsal view of the lectotype of
V. c. cumingi
(BMNH 1946.8.31.5). The original labels which according to Günther (1872) were written by H. Cuming and W. Martin read “Isle of Mindana[d]o” and “Mindana[d]o, 57.6.13 186 [the former collection number],
Varanus Cumingii
”, respectively. Photo by André Koch.
For details about scalation features and colour pattern of the remaining
Philippine
members of the
V. salvator
complex we refer to
Tables 3
and
5
.
Intraspecific variation.
The main morphometrics and scalation features of
V. cumingi
are provided in
Tables 3
and
5
. Our investigations confirm striking variation in colour patterns of
V. cumingi
(see also
Gaulke 1991a
: 161). In general, specimens from Mindanao, the
type
locality, show a brighter and less distinct colour pattern on the dorsal side compared with the populations from other islands within the distribution range (
Tab.
5). On this basis, the Mindanao population has been referred to as the bright morphotype of the taxon
cumingi
by
Gaulke (1992a)
and
Koch
et al.
(2007)
. Monitors from Mindanao exhibit an obvious tendency towards yellow crossbands on the dorsal side rather than transverse rows of spots or ocelli. In addition, some specimens exhibit a more-or-less continuous yellow medio-dorsal stripe, which extends from the neck towards the base of the tail (
Fig. 4
). In other specimens from Mindanao, an augmentation of yellow transverse rows on the dorsal side is recognisable. The ventral colour pattern of the Mindanao population may consist of V-shaped, pointed bars or crossbands on a bright background colour. In contrast,
V. cumingi
from Samar, Leyte and Bohol, known as the dark morphotype (
Gaulke 1992a
;
Koch
et al.
2007
), is characterised by a dorsal colour pattern rich in contrast on a black background colour and well defined yellow spots, ocelli or other markings arranged in transverse rows (
Fig. 14
).
Gaulke (1992a)
observed that specimens from Bohol showed a whitish rather than yellowish throat. Basilan specimens that have also been assigned to the dark phenotype of
V. c u m i n g i
by
Gaulke (1992a)
were not available for detailed analysis. Besides these geographical variations in colour pattern, some kind of ontogenetic change in colour pattern is observable in
V. cumingi
(see
Wicker
et al.
1999
). Juveniles are much darker. In particular, the head shows
salvator
-typical dark crossbands on the snout, and distinct transverse rows of small bright spots on the dorsal side. As the juveniles mature, the characteristic yellow
cumingi
colouration becomes more pronounced with extended bright parts on the head and back. This extraordinary colour change is unique for
V. c u m i n g i
amongst members of the
V. salvator
complex.
Due to the geographically correlated differences in colour pattern between allopatric island populations of
V. c u m i n g i
, we describe the populations from Samar, Leyte, and Bohol as a new subspecies of this remarkable
Philippine
water monitor species as already claimed by
Gaulke (1991a)
.
Conservation status.
Currently,
V. cumingi
is listed as “least concern” by the IUCN (Sy
et al.
2007). Nevertheless, this relatively common
Philippine
monitor lizard species is suspected decreasing because of overharvesting.