cryptic species within the dendrophidion vinitor complex in middle ...

SPECIES IN THE DENDROPHIDION VINITOR COMPLEX N Cadle 185
some of the characters particularly useful
for the three species covered in this paper.
Dorsocaudal reductions were recorded as
the subcaudal at which the reduction from
eight to six dorsal scale rows on the tail
occurred (Lieb, 1988). The point of posterior
reduction of the dorsal scales was
scored on each side of selected specimens
as the ventral scute number at which the
reduction occurred and the dorsal rows
involved. For purposes of analyzing intraspecific
differences in mean snout–vent
length (SVL) of adult males and females,
specimens with SVL . 450 mm were
considered adults (Goldberg, 2003; Stafford,
2003). Similarly, because relative tail
length increases proportionally with SVL,
the range of adult relative tail length (RTL)
was assessed for individuals with SVL .
300 mm because analyses showed that RTL
approaches an asymptote at approximately
this size. When measurements or meristic
data for particular specimens are referred to
in the text, these data are based on my
examinations (data encountered in the
literature sometimes differ).
Intraspecific mean differences between
male and female sizes and scale counts were
tested for significance using t tests after
testing for homogeneity of variances. P-
values reported for intraspecific comparisons
are two-tailed pairwise comparisons; in
the few cases in which there was a priori
expectation for one sex or the other to have
a greater value for a character (e.g., males
having a longer tail or more subcaudals than
females), p-values for one-tailed tests did
not differ from the two-tailed comparison.
Similar procedures and two-tailed tests
were used for interspecific comparisons,
which were analyzed separately for each sex
except in cases in which intraspecific sexual
differences were nonsignificant (sexes
pooled in these cases). Means, standard
deviations, and results of intraspecific statistical
comparisons for most meristic counts
are presented in Table 1, and only summaries
are given in the text.
For determining tail breakage frequencies,
I counted as ‘‘broken’’ only tails with a
clearly healed cap on the stump; thus, I
record the frequency of ‘‘broken/healed’’
tails. In my survey of literature, it was
apparent that some authors included any
specimens with a tail fracture in their tail
breakage frequency calculations (e.g., at
least one paper recorded multiple fracture
points in a high percentage of specimens).
However, this method artificially inflates
estimates of tail breakage frequencies because
of the inclusion of snakes whose tails
were broken during or after capture, or
even subsequent to storage in a museum jar.
Although these specimens may offer clues
as to the fragility of the tail in a particular
species, they are not especially useful for
comparative purposes.
I scored the number of keeled dorsal
scale rows on the neck, at midbody, and just
anterior to the vent. Keels in all species of
Dendrophidion are best developed (i.e.,
encompassing more dorsal rows) on the
posterior body, but the number of keeled
rows on the neck or at midbody often show
interspecific differences that provide discriminating
characters. The three species
covered in this paper are similar in their
patterns of keeling. The basic pattern of
temporal scales in D. vinitor and the new
species here described is 2+2 (two primary,
two secondary). However, temporal scales
were often divided by a vertical suture
(usually dividing the scale asymmetrically),
or, less commonly, two temporal scales were
fused or a temporal was fused with a
supralabial. I recorded these divisions or
fusions separately from the basic pattern.
For example, a specimen might be recorded
as having 2+2 temporals but with the upper
primary and upper secondary fused on one
side. Because of frequent asymmetry, temporal
scales and supra- and infralabials were
scored on each side of a specimen, and each
side was treated as an independent observation;
the total count of observations for
these scale characters (Table 1) is thus
about twice the number of specimens
examined (damage sometimes prevented
scoring on one or both sides of a given
specimen).
Bulletin of the Museum of Comparative Zoology harv-160-04-01.3d 11/4/12 19:58:33 185