systematics of snakes of the dipsas oreas complex - BioOne

Dipsas oreas Complex in Ecuador and Peru • Cadle 85
vertical markings separated by a narrow
whitish strip. In some specimens the contralateral
markings meet in the vertebral
region, forming more or less complete
bands, although the vertebral region tends
to be invested with dark pigment so that
the pale central regions of the markings
are interrupted. In others (e.g., MCZ
8431; Fig. 7), contralateral markings fail to
meet middorsally, forming lateral bars with
pale centers that are closed off on their
dorsal edges by black pigment. The markings
have vertical edges and extend ventrally
to the first scale row or the outer
edge of the ventrals. Contralateral markings
are frequently offset virtually the entire
length of the body (e.g., Fig. 7) or on
the posterior body only (most specimens).
The markings (i.e., each black–white–
black triplet) are 5–6 scale rows in width
anteriorly but narrow to about 3 rows by
midbody. Interspaces anteriorly are narrower
than the bands or bars (approximately
3 scale rows), whereas they are
wider than the markings posteriorly (5–6
scale rows). The venter is dull grayish
brown with a dense covering of dark
brown squarish markings that tend to be
concentrated toward the outer edges of
the ventrals, sometimes forming longitudinal
arrays (Figs. 2–4).
The top and sides of the head are heavily
marked with irregular dark markings on
a pale brown ground color (Fig. 6). The
markings are so extensive in some specimens
that most of the top of the head is a
solid dark brown, with just occasional light
areas of the ground color showing through
as fine reticulations or vermiform marks.
Upper and lower labials are pale brown
with dark brown spotting, but the dark
stippling often is not especially concentrated
along suture lines as in many species
of snakes.
Two small juveniles (MCZ 8431, 210
mm SVL; BMNH 1946.1.21.27, 138 mm
SVL) have patterns identical to those of
adults, but more contrasting (Fig. 7; Kofron,
1982: fig. 1). The ground color is grayish
white, and the dark markings are dark
chocolate brown to blackish. The dorsal
markings have pale centers and appear as
blackish vertical bars (or narrow ellipses)
enclosing whitish centers. Interspaces between
the markings are whitish, but individual
scales are speckled with tiny irregular
dark brown flecks. The top of the
head of MCZ 8431 is whitish with heavy
reticulations and irregular spots so that
much of the top and sides of the head are
dark. The gular regions and venter are
whitish with a pattern of bold irregular
spots and blotches; on the venter these
tend to form bold longitudinal streaks. If
these two specimens are representative of
very small individuals of Dipsas ellipsifera,
this species appears already to have the
adult color pattern even as small juveniles,
a contrast with the developmental pattern
in D. elegans and D. oreas (see the following
species accounts for discussion). In the
last two species, smallest juveniles have
solid bands that develop pale centers during
early juvenile ontogeny, thus acquiring
the adult patterns sometime after hatching.
Hemipenis
The following description is based on
the inverted organ of UMMZ 83697 examined
in situ. The organ had previously
been slit along its medial edge and the retractor
muscle had been cut distal to its
point of division.
Total length of the organ is 18 mm and
it is slightly bilobed distally. The retractor
muscle is divided proximally for 4 mm.
The sulcus spermaticus (in the lateral wall
of the organ) divides 9 mm from the base
of the organ within the capitulum; the tips
of its branches end approximately 1 mm
short of the distal tips of the lobes. The
basal region of the organ is sparsely ornamented
with minute spines. The midsection
has a battery of enlarged hooked
spines encircling the organ just proximal
to the capitulum; the battery is about 3
spines across around the entire organ. The
capitulum is set off by a distinct overhang
and is completely ornamented distally with