Homalopsis albomaculatus
Duméril, Bibron, and Duméril, 1854 Érpétologie générale...reptiles. Paris 7(2):974. Type locality: Padang,
Sumatra. Holotype: MNHN c3452.
Hypsirhina albomaculata -
Jan, 1863, Elanco systematico degli ofidi, p. 77.
Enhydris albomaculata - Haas,
1950 Treubia, 20(3):575.
Sumatranus albomaculatus
Murphy and Voris, 2014:37.
Etymology. The name albomaculata
presumably refers to the white spots on the head and dorsum, and is derived
from the Latin albus meaning “white” and macula meaning “spot”.
Distribution. Sumatranus
albomaculatus is a Sunda Shelf endemic. This species lives on the following
islands that are near Sumatra: Nias, Pulo, Simeuluë, Sibigo, and Sinabang. Its
presence on Sumatra proper is questionable. Gyi (1970) may have been confused
when he listed Java within the range of this species; the place names he listed
are small islands around Sumatra and none of these names are associated with
Java. In fact, other than the type locality all of the localities appear to be
offshore satellites of Sumatra. This snake’s presence on numerous small islands
suggests it may have a tolerance for saltwater, or if it is freshwater it may
have been isolated on these islands for long periods. The web site for the Pula
Simeulue Wildlife Reserve lists albomaculatus
as present. Simeulue is surrounded by deep water and is about 100 km NW of
Sumatra. This population has probably been isolated from other populations for
a while. Sumatranus albomaculatus inhabits
the Sunda Shelf and Philippine Bioregion of Wikramanayake et al. (2002).
Diagnosis. A homalopsid that has 27 scale rows at mid-body (26 - 28),
at least one literature report described three specimens with 25 scale rows (I
have not examined any specimens with 25 scale rows). Four upper labials contact
the loreal. These labials (except the first) have a broad dorsal edge. The
upper labials posterior to the eye may be divided, particularly the last large
labial. The first five or six lower labials contact the anterior chin shield.
This species may be most easily confused with Phytolophis punctata, which has 25 or 27 scale rows at mid-body, a
mostly black dorsum, and with which it may have an over-lapping geographical
distribution. However, P. punctata
has horizontally divided labials under the eye, a small (usually single)
internasal that is isolated from the loreal. S. albomaculatus has a large internasal scale that contacts the
loreal. P. punctata also has four labials contacting the loreal but these taper
toward the dorsal edge. Subsessor bocourti has 27 or 29 scale
rows at mid-body; it usually has a single internasal, and has upper labials 1 -
2 or 1 - 3 in contact with the loreal. It also has horizontally divided upper
labials behind the eye. Dieurostus dussumieri also has 27 scale
rows at mid-body but it can be distinguished from albomaculatus by a divided internasal which does not contact the
loreal in the one specimen examined, and upper labials 1 - 3 contacting the
loreal (albomaculatus usually does
not have the first labial contacting the loreal). Additionally, D. dussumieri is known only from
southwestern peninsular India. See Table 5 for a comparison of species with 27
scale rows at mid-body.
Size. The largest individual measured was a female with a total length
of 625 mm and 75 mm tail. The largest male measured had a total length of 520
mm with a 90 mm tail. The smallest individual measured had a 260 mm SVL with a
70 mm tail. Gyi (1970) noted that females have significantly shorter tails than
males. Data collected for this study show females have tails that are 12.5 -
14.4% of the SVL, while males have tails that are 17.1 - 26.9% of the SVL.
External Morphology. The head is distinct from the neck and slightly
depressed. The eyes are dorsolateral and are small; their diameter is about
equal to the width of the prefrontal scales, or about 1.5 times the eye-nostril
distance.
On the head the
rostral is pentagonal and two or three times broader than tall, it is slightly
visible from above. The nasals are semi-divided with the cleft touching the
loreal or the second labial, or divided with the cleft touching the labial or
loreal and the internasal. The internasal scale is divided
and slightly penetrates the nasals from behind. They are small, each covers
about half the area of the nasal, and they are in contact with each other. The
prefrontal scales are about twice the size of the internasals in area, they are
paired and in contact. Rooj (1917) reported that none of 10 specimens from
Simalur have divided prefrontals. The frontal is pentagonal to hexagonal and
relatively short, about 1.25 times the length of the supraocular. The parietals
are large and entire, almost twice the area of the frontal. The supraocular is
single and the anterior margin is only slightly narrower than the posterior
margin. The loreal is single and in contact with upper labials 2 - 4 and
occasionally 1 - 4. The single preocular is taller than wide. The postocular
can be single or paired, it paired the two scales are about equal in size. The
temporal formula is 1 + 2 + 3 or 1 + 2 + 4; the third row is indistinguishable
from the occipital scales. The upper labials number eight, occasionally nine;
labials posterior to the eye may be divided horizontally. The fourth and or
fifth upper labials enter the orbit, the dorsal edge of these scales have been
squared off.
On the chin lower
labials number 11 - 14, with number seven or eight being the largest. They are
extremely tuberculate. The first on each side form the mental groove. The first
five or six are in contact with the anterior pair of chin shields. The anterior
pair of chin shields is 3-4 times larger than the second pair. The second pair
is separated by a smaller pair of scales. Both pairs are tuberculate. Gular
scales number 6 - 8.
On the body the dorsal
scales on the neck are smooth and in 25 - 29 rows. The first row is almost
square; the scales become more lanceolate toward the vertebral line; the scales
at mid-body are similar and in 26 - 28 rows but usually 27 rows; the scales at
posterior body are similar and in 23 -
25 rows. The scales on the tail are similar to those on the dorsum. The ventral
scales are 3-4 times wider than the height of a nearby dorsal scale. The
ventral scales in 11 males ranged from 140 - 151 (X¯ = 145.8); and in five
females ventral scale counts ranged from 140 - 151 (X¯ = 145.8). Several of the
specimens examined had ventral scales that were divided. The anal plate is
divided and it is about 1.5 times the length of the preceding ventral.
On the tail the subcaudal
scales in 11 male ranged from 44 - 51 (X¯ = 48.2); and in seven females ranged
from 36 - 42 (X¯ = 37.8). The posterior of the body is slightly depressed. At
the base of the tail the width is about 75% of the height.
Color and pattern on
the crown of the head are uniform, the rostral and the first three upper
labials are dark in color as is the crown. There are white spots on labial four
and those labials posterior to it. The chin is white with black spots. The
dorsum is dark with scattered light spots. There are short lateral crossbars.
The mixture of dark blotches and white spots on the body produce a mottled
appearance. The ventral scales have dark brown pigment on the anterior edge but
it may also be centered or off to one side. The ventral side of the tail is
uniform black.
Natural History. Nothing is known about this species habitat and diet.
Litter size data: One specimen (USNM 30767) contained three eggs and has an SVL
of 520 mm.