systematics of snakes of the dipsas oreas complex - BioOne

Dipsas oreas Complex in Ecuador and Peru • Cadle 123
formation extends its range into Peru. Dipsas
latifasciatus and D. latifrontalis have
been reported from eastern Ecuador and/
or Peru, but my examination of specimens
disclosed some systematic and nomenclatural
problems relative to the treatment of
these species in the literature. Detailed locality
data on specimens of these taxa I
examined are given in the Specimens Examined
and Locality Records. See Note
Added in Proof, p. 136.
Dipsas gracilis
Dipsas gracilis (Boulenger, 1902) was
not recorded south of Guayaquil, Ecuador
(Peters, 1960a) until Tello (1998) reported
it from a lowland (620 m) evergreen rain
forest in extreme northwestern Peru on
the basis of MUSM 17589 (Quebrada de
los Naranjos, Tumbes department). I provisionally
refer two additional specimens
from northern Peru to D. gracilis, MUSM
2700–01 (Río Quiroz valley, Piura department).
Although D. gracilis thus far has
been reported in detail only from western
Ecuador (Peters, 1960a; Peters and Orejas-Miranda,
1970), Perez-Santos and Moreno
(1988, 1991) reported the species
from Colombia without providing documentation.
A specimen of Dipsas that I examined
from northwestern Colombia near
the Panama border (FMNH 74376) had
been previously identified as D. gracilis,
but I tentatively refer this specimen to D.
viguieri; see comments in the following
section (key to species) concerning some
difficulties in distinguishing D. gracilis and
D. viguieri. I here comment on characteristics
of the Peruvian specimens of D.
gracilis, whose scutellation and other characters
are summarized in Table 4. Unfortunately,
my examination of MUSM 17589
was brief, and basic data were not completed,
although the specimen is well preserved.
All three Peruvian specimens are
males, so the most relevant comparison
would be males of Ecuadorian D. gracilis
(Table 4).
MUSM 17589 was obtained during a biological
inventory of the lowland tropical
forests of Tumbes department (Wust,
1998a). It is an adult male in excellent condition
with well-everted hemipenes. The
specimen has 22 broad black bands (encompassing
6–8 dorsal scale rows) that extend
completely across the venter. Interspaces
are whitish (3–4 dorsal rows in
breadth) with brownish stippling concentrated
in the central part of each interspace.
The head is white with many irregular
black markings on the top and sides.
Quebrada de los Naranjos, whence
MUSM 17589 comes, is within a region of
lowland humid tropical forest extending
southward from Ecuador into far northwestern
Peru (Chapman, 1926; Koepcke,
1961). This forest is the only truly lowland
humid forest in western Peru and has never
been extensive; remaining fragments are
now a protected reserve (Wust, 1998a). Tello
(1998:79) described the vegetation of
Quebrada de los Naranjos as ‘‘an ephemeral
thicket composed mostly of small plants of
the Rubiaceae and ferns.’’ Wust (1998b:22)
stated that ‘‘In the hills of Quebrada de los
Naranjos the forest is humid and evergreen,
reaching more than 20 m in some parts, and
with a more or less uniform canopy dominated
by [Ficus, Centrolobium, Vitex, Pouteria,
Ocotea, Bombax, and Gallesia].’’
MUSM 2700–01 are assigned only provisionally
to Dipsas gracilis because they
are in poor condition (soft, poorly preserved,
and with pattern elements obscure).
The MUSM catalogues indicate
that the specimens were collected 17
March 1966 (collector not listed) from the
imprecise locality ‘‘Valle del Río Quiroz.’’
Additional geographical indications in the
catalogue (perhaps added later when the
specimens were catalogued in Lima) include
‘‘Piura [department], Pv. [Provincia]
Ayabaca.’’ The Río Quiroz flows northwestward
across extreme northern Piura
department (western versant of the Andes)
north of the Cordillera Guamani and eventually
joins the Río Chira, which drains the
southern part of Loja Province, Ecuador.
Ayabaca Province is at the northern extremity
of Piura department on the Ec-