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A NEW SPECIES OF THE GEOPHIS SIEBOLDI GROUP
(SQUAMATA: COLUBRIDAE) EXHIBITING COLOR PATTERN
POLYMORPHISM FROM GUERRERO, MEXICO
CARLOS J. PAVO
´N-VA
´ZQUEZ
1
,URI O. GARCI
´A-VA
´ZQUEZ
1
,JEAN C. BLANCAS-HERNA
´NDEZ
2
,
AND ADRIA
´NNIETO-MONTES DE OCA
1,3
1
Museo de Zoologı
´a and Departamento de Biologı
´a Evolutiva, Facultad de Ciencias, Universidad Nacional Auto
´noma de
Me
´xico, Apartado Postal 70-153, Me
´xico 04510, DF, Me
´xico
2
Instituto de Investigacio
´n Cientı
´fica, A
´rea de Ciencias Naturales, Universidad Auto
´noma de Guerrero, Chilpancingo,
Guerrero, Me
´xico
ABSTRACT: A new species of the colubrid genus Geophis is described from the Sierra Madre del Sur of
Guerrero, Mexico. The new species possesses all of the diagnostic characters of the sieboldi group, but differs
from all of the other species in the group by having dorsal scales arranged in 17 rows, 133–139 ventrals in
females and 130–137 in males, 24–31 subcaudals in females and 34–39 in males, keeled dorsal scales on at
least the posterior three-fourths of the body, apparently no apical pits, and a light nuchal collar in juveniles.
The new species fills a gap in the distribution of the sieboldi group between Michoaca
´n and Oaxaca, and is
the first Mexican species of the genus reported to exhibit both a unicolor (uniformly dark) and a bicolor (with
dark markings on a red background color) body and tail dorsal patterns, a polymorphism similar to that
previously documented in few lower Central American species.
RESUMEN: Se describe una nueva especie del ge
´nero de colu
´bridos Geophis de la Sierra Madre del Sur de
Guerrero, Me
´xico. La nueva especie posee todos los caracteres diagno
´sticos del grupo sieboldi, pero difiere
de todas las dema
´s especies en el grupo por tener escamas dorsales dispuestas en 17 hileras, 133–139
ventrales en hembras y 130–137 en machos, 24–31 subcaudales en hembras y 34–39 en machos, escamas
dorsales quilladas en al menos las tres cuartas partes posteriores del cuerpo y un collar nucal claro en jo
´venes,
y por aparentemente carecer de fosetas apicales. La nueva especie llena un hueco en la distribucio
´n del grupo
sieboldi entre Michoaca
´n y Oaxaca, y es la primera especie mexicana reportada que exhibe tanto un patro
´n
dorsal del cuerpo y la cola unicolor (uniformemente oscuro) como otro bicolor (con marcas oscuras sobre un
color de fondo rojo), un polimorfismo similar al documentado previamente en algunas especies de la regio
´n
ma
´s suren
˜a de Ame
´rica Central.
Key words: Color pattern polymorphism; Colubridae; Geophis; Guerrero; Mexico; New species;
Taxonomy
THE COLUBRID genus Geophis is the fourth
largest genus of snakes in the Western Hemi-
sphere, with 47 currently recognized species
(Townsend, 2009). The genus occurs from
the Sierra Madre Occidental in southwestern
Chihuahua and the Sierra Madre Oriental in
southern Tamaulipas, Mexico, through the
central highlands and Atlantic lowlands of
Central America to the highlands of northern
and western Colombia, between 13 and
2744 m of elevation (Wilson and Townsend,
2007). Downs (1967) divided the genus into
seven species groups, mainly on the basis of
their external morphology (number of species
in each group in parentheses): chalybeus (5),
championi (4), dubius (10), latifrontalis (3),
omiltemanus (4), semidoliatus (4), and sieboldi
(17).
The sieboldi group was originally composed
of nine taxa: Geophis brachycephalus (Cope,
1871), G. dunni Schmidt, 1932, G. hoffmanni
Peters, 1859, G. nasalis (Cope, 1868), G. petersii
Boulenger, 1894, G. russatus Smith and Wil-
liams, 1966, G. sallei Boulenger, 1894, G.
sieboldi (Jan, 1862), and G. zeledoni Taylor,
1954 (Downs, 1967). However, six new species
have been subsequently added to the group: G.
bellus Myers, 2003, G. betaniensis Restrepo and
Wright, 1987, G. damiani Wilson et al., 1998,
G. pyburni Campbell and Murphy, 1977, G.
talamancae Lips and Savage, 1994, and G. tectus
Savage and Watling, 2008.
In addition, G. laticollaris, previously in the
synonymy of G. sallei,andG. nigroalbus,pre-
viously in the synonymy of G. brachycephalus,
3
CORRESPONDENCE: e-mail, anietomontesdeoca@me.com
Herpetologica, 67(3), 2011, 332–343
E2011 by The Herpetologists’ League, Inc.
332
were resurrected by Smith and Chiszar (1992)
and Myers (2003), respectively.
Downs (1967) defined the sieboldi group by
the following characters: head moderately dis-
tinct from anterior end of body or not; snout
long, projecting well beyond lower jaw; eye
small to moderate; rostral not produced poste-
riorly between internasals; internasals and
postnasals short; prefrontals and loreals elon-
gate; supraocular forms about posterior half of
dorsal margin of orbit; parietals short, broad;
no anterior temporal; dorsal scales in 15 or 17
rows, keeled at least above vent; paired apical
pits present (apparently absent in G. petersii);
ventrals 118–151 in males, 118–154 in fe-
males; subcaudals 28–51 in males, 23–43 in
females; percentage tail of total length 14.1–
21.2 in males, 11.0–17.6 in females; maxilla
extends anteriorly to suture between supra-
labials 2 and 3; anterior extension about equal
to that of palatine; maxilla dorsoventrally com-
pressed; in lateral view, posterior third of
maxilla curves ventrally; anterior tip of maxilla
toothless (first tooth at tip of maxilla or pre-
ceded by a short toothless area in G. zeledoni),
pointed; 8–15 maxillary teeth, subequal in
length; posterior end of maxilla tapers to blunt
point; anterior end of ectopterygoid single, not
expanded; postorbital bone narrow.
The geographic range of the sieboldi group
is nearly that of the entire genus, extend-
ing from Michoaca
´n, Mexico to northwestern
Colombia; it is the only group present in
South America (Downs, 1967). Herein we
argue that the assignment of one specimen
from Amula, Guerrero, to G. sieboldi by
Downs (1967) was likely in error (see below).
Thus, seven species of the sieboldi group are
known from Mexico: G. sieboldi and G.
pyburni, from western Michoaca
´n; G. petersii,
from northern Michoaca
´n and Mexico City;
G. laticollaris and G. russatus, from extreme
western Oaxaca; G. sallei, from south-central
Oaxaca; and G. nasalis, from the Pacific
versant of Chiapas, Mexico, and Guatemala.
In their taxonomic revision of the sieboldi
group in lower Central America and Colom-
bia, Savage and Watling (2008) stated that,
although several species of Geophis exhib-
it red bands on a black ground color (G.
damiani and G. cancellatus in the sieboldi
group; G. laticinctus and G. semidoliatus in
other species groups) or black bands on red
(G. russatus and possibly G. dunni in the
sieboldi group; G. duellmani in another spe-
cies group), only three species in the sieboldi
group (G. brachycephalus,G. talamancae, and
G. tectus), all from lower Central America, are
unique in the genus in exhibiting two basic
dorsal color patterns: one pattern, unicolor, is
characterized by a uniform black dorsal sur-
face of the body and tail, whereas the other
pattern, bicolor, is composed of red markings
(markings light in preservative in G. tectus,
but probably red in life) on a black back-
ground color on at least part of the body (in
the three species) and tail (in G. brachyce-
phalus and G. tectus; upper surface of the tail
black in G. talamancae).
Herein we describe a new species of the
sieboldi group from the Sierra Madre del Sur
of south-central Guerrero on the basis of a
sample of 17 specimens. The new species is
most remarkable in exhibiting a body and tail
dorsal pattern that may be unicolor (uniformly
dark) or bicolor (with dark markings on a red
background color). In addition, this is the first
confidently known species of the sieboldi
group from Guerrero, thus filling a gap in
the distribution of the group between Mi-
choaca
´n to the northwest and Oaxaca to the
southeast.
MATERIALS AND METHODS
Fieldwork was conducted in the Sierra Madre
del Sur of Guerrero during the summer of 2006.
Seventeen specimens were collected in the
region of El Molote. All specimens were fixed
in 10% buffered formalin, preserved in 70%
ethanol, and deposited in the herpetological
collection of the Museo de Zoologı
´aofthe
Facultad de Ciencias, Universidad Nacional
Auto
´noma de Me
´xico (MZFC). Nomenclature
of scales follows Downs (1967). Scale counts
were performed with the aid of a dissecting
microscope. The ventrals were counted as sug-
gested by Downs (1967). Bilateral characters
were scored on both sides. When the con-
dition of a given character was not identical
on both sides, the conditions on the left and
right sides are given, in that order, separated
by a slash (/). Measurements were taken with a
ruler, digital calipers, or an ocular micrometer
September 2011] HERPETOLOGICA 333
to the nearest 0.1 mm. Head length was
measured from the point of the snout to the
posterior end of the parietals. All scale
dimensions were measured at their maximum.
Color descriptions and codes (in parentheses)
follow Smithe (1975). Dentition characters
were examined after removal of the maxilla
and ectopterygoid from the skull and cleans-
ing in a dilute solution of NaOH. The
diagnosis was based on both the specimens
examined and the relevant literature (Camp-
bell et al., 1983; Downs, 1967; Lips and
Savage, 1994; Nieto-Montes de Oca, 2003;
Savage and Watling, 2008; Smith and
Holland, 1969; Townsend, 2009; Wilson and
Townsend, 2007). In the case of G. sieboldi,
we tentatively reject Downs’ (1967) assign-
ment of a specimen from Amula (5Almo-
longa) to this species (see below). A list of the
specimens examined is given in Appendix I.
SPECIES ACCOUNT
Geophis occabus sp. nov.
(Figs. 1–3)
Holotype.—MZFC 25530, a female from El
Molote, municipality of Atoyac de A
´lvarez, Guer-
rero, Mexico (17u25914.40N, 100u10915.70W; da-
tum 5WGS84), elevation 1787 m, collected by
J. C. Blancas-Herna
´ndez.
Paratypes.—Sixteen specimens from the
municipality of Atoyac de A
´lvarez, Guerrero,
Mexico: nine (MZFC 22167–22170, 25528,
25529, 25531, 25532, 25552) from the same
locality as the holotype and seven (MZFC
22160, 22162–22166, 25551) from 1.4 km E
of El Molote (17u25910.60N, 100u09928.80W),
elevation 2014 m, collected by J. C. Blancas-
Herna
´ndez.
Referred specimens.—One specimen from
the same locality as the holotype (MZFC
uncatalogued; field number JCBH 651), col-
lected by J. C. Blancas-Herna
´ndez.
Diagnosis.—Geophis occabus may be distin-
guished from all species in the championi and
semidoliatus groups, and all species in the
sieboldi group except for G. dunni,G. nasalis,
and G. sieboldi, in having dorsal scales arranged
in 17 rows (versus dorsal scales arranged in 15
rows in the other species); from all species in
the chalybeus and latifrontalis groups, and most
species in the dubius group (G. anocularis,
G. dubius,G. duellmani,G. fulvoguttatus,G.
immaculatus,G. rhodogaster,andG. nepho-
drymus), by having keeled dorsal scales on at
least the posterior three-fourths of the body
(versus dorsal scales smooth except above the
vent in G. dubius and some specimens of G.
anocularis; smooth throughout the body in the
other species); and from all species in the
omiltemanus group, by having the fifth supra-
labial and parietal in contact (versus fifth supra-
labial and parietal separated by one anterior
temporal in the other species).
Geophis occabus differs from the remaining
species in the dubius group as follows: from
FIG. 1.—Geophis occabus, head of holotype (MZFC
25530) in dorsal view (top), left lateral view (middle), and
ventral view (bottom). The horizontal bars represent
3 mm.
334 HERPETOLOGICA [Vol. 67, No. 3
G. carinosus and G. juarezi, by usually having
more ventrals (133–139, n56 in females, and
130–137, n511 in males; versus 125–136,
n58 in females, and 116 –123, n56in
males of G. carinosus; and 118–124, n53in
females, and 114 in the only known male of G.
juarezi) and fewer subcaudals (29–31, n56
in females, and 34–39, n510 in males; versus
37–43, n58 in females, and 45–49, n56in
males of G. carinosus; 49 in the only female
with a complete tail and 55 in the only male
known of G. juarezi); and from G. rostralis,by
having the first pair of infralabials in contact
(versus first pair of infralabials separated by
one pair of gular shields in G. rostralis).
Geophis occabus differs from the remaining
species in the sieboldi group as follows: from
G. dunni, by having fewer subcaudals in
females (29–31, n56 versus 36 in the only
known specimen of G. dunni); from G.
nasalis, by having a light collar in juveniles
(versus light collar absent in juveniles of G.
nasalis) and usually more ventrals in males
(130–137, n511 versus 115–130, n5175 in G.
nasalis), and by the apparent absence of apical
pits (versus paired apical pits in G. nasalis); and
from G. sieboldi, by having keeled dorsals on at
least the posterior three-fourths of the body
(versus keeled dorsals only on the posterior half
of the body in G. sieboldi), fewer ventrals (133–
139, n56 in females, and 130–137, n511 in
males; versus 147–153, n52infemales,and
143–147, n54inmalesofG. sieboldi), and
usually fewer subcaudals (24–31, n56in
females, and 34–39, n510 in males; versus 35–
36, n52 in females, and 37–42, n54inmales
of G. sieboldi).
Description of holotype (Fig. 1).—An adult
female; head length 56.8 mm, snout–vent
length (SVL) 5153 mm, tail length 525 mm.
Head slightly distinct from anterior end of
body; snout long, contained 2.3 times in head,
rounded from above, projecting anteriorly far
beyond lower jaw; rostral slightly broader than
high, slightly produced posteriorly between
internasals, portion visible from above 0.3
times as long as its distance from frontal, 1.5
times as long as internasals common suture,
with posterior end approximately at level of
anterior margin of nostrils; internasals broader
than long (breadth/length 51.7/1.9), rounded
anteriorly, in lateral contact with anterior and
posterior nasals, their length and common
suture ca. 0.4 and 0.2 times as long as pre-
frontals common suture, respectively; prefron-
tals in lateral contact with postnasal and loreal,
their length ca. 0.7 times length of snout, their
common suture ca. 0.6 times frontal length;
FIG. 2.—Variation in the bicolor dorsal pattern of Geophis occabus. See text for details.
September 2011] HERPETOLOGICA 335
frontal about as broad as long (breadth/length
ratio 51.0), angulate anteriorly; supraocular
large, quadrilateral from above, in moderately
broad contact with prefrontal and postocular,
in broad contact with frontal and parietal,
approximately as long as horizontal diameter
of eye, 0.5/0.6 times as long as loreal, forming
about posterior three-fourths of dorsal margin
of orbit, ventral margin not projecting anteri-
orly or posteriorly beyond margins of orbit;
parietals 1.4/1.3 times as long as broad, their
length approximately 0.5 times head length,
their common suture 0.7 times as long as
frontal; one postocular, 1.4/1.7 times as high
as long, slightly smaller than supraocular;
nasal divided; postnasal 1.1/1.4 times as long
as prenasal; combined length of prenasal and
postnasal ca. 0.8 times loreal length; loreal 1.8
times as long as deep, contained 2.1/1.9 times
in snout length, 1.8 times as long as horizontal
diameter of eye, dorsal margin nearly straight;
eye small, contained 3.3 times in snout length,
its vertical diameter 0.9/0.8 times its distance
from lip; supralabials 6/6, first and second in
contact with postnasal, second and third in
contact with loreal, third and fourth entering
orbit, fifth largest, in contact with parietal; ven-
tral margin of third supralabial 1.3/1.4 times
that of second supralabial; ventral margin of
fifth supralabial 0.8/0.9 times that of fourth
supralabial, 0.5/0.6 times that of sixth supra-
labial; anterior temporal absent; one posterior
temporal, separating sixth supralabial from
parietal; posterior temporals separated poste-
riorly from each other by four nuchals; pos-
terior temporal presumably fused with one or
two nuchals on left side, with one nuchal
on right side. Mental 1.9 times as broad as
long, rounded anteriorly, separated from chin
shields by first infralabials; infralabials 7/7, first
to third in contact with anterior chin shields,
third and fourth in contact with posterior chin
shields; anterior chin shields 1.5/1.4 times as
long as broad, 1.1/1.5 times as long as posterior
chin shields; posterior chin shields broadly
separated from each other by one midgular
scale; two midgular scales; numerous tiny
tubercles present on mental and first infra-
labials, gradually disappearing posteriorly.
Dorsal scales in 17-17-17 rows, smooth on
nape and first third of body, gradually becoming
distinctly keeled on posterior two-thirds of body,
above vent, and on anterior half of tail; no
evident apical pits; ventrals 138; subcloacal
scute (‘‘anal plate’’) single; paired subcaudals 29.
Color (in preservative): Color pattern com-
posed of dark and pale areas (dark grayish
brown [20] and pale horn [92], respectively)
disposed as follows: dorsal half of head and
dorsal scale rows on body and tail dark, except
for (1) pale collar on posterior end of head and
anterior end of nape, narrowest middorsally,
widest mid-laterally; its anterior margin extend-
ing across midline at level of ca. three-fourths
length of parietals, curving laterally at levels
of ca. one-half/one-third length of primary
temporals, then ventrally, reaching upper lip
at levels of ca. one-fourth/one-third length of
sixth supralabials and extending immediately
posterior to anterodorsal corner of seventh
infralabials, its posterior margin extending
across midline at level of one-half length of
second medial nuchal, curving laterally and
then ventrally to posterior end of second scale
posterior to seventh infralabials and beyond,
collar merging ventrally into pale venter; and
(2) pale medial to posteromedial spot on each
scale of first dorsal row on anterior end of body,
gradually becoming smaller, restricted to pos-
teroventral margin of each scale posteriorly,
disappearing at ca. level of mid-body. Ventral
surface mostly pale, immaculate except for (1)
mental, first to fifth infralabials, and anterior
margins of anterior chin shields about uniform-
ly dark (dark pigment gradually becoming
sparser posteriorly on fifth supralabials), sixth
infralabials mottled with dark pigment, and
seventh infralabials with dark anterodorsal spot
on ventral half of head; (2) dark streak on
anterolateral margin of each ventral scale; and
(3) dark, irregular speckles scattered on anterior
and lateral margins of subcaudals on anterior
portion of tail, gradually denser posteriorly,
forming transverse band on anterior margin of
subcaudals, bands gradually becoming wider
posteriorly, covering subcaudals entirely on
posterior end of tail.
Dentition.—The description is based on the
dentition of the left side in one of the para-
types (MZFC 25531). Maxilla extending ante-
riorly to level of suture between second and
third supralabials, dorsoventrally compressed;
in lateral view, posterior third of maxilla curves
ventrally; anterior tip of maxilla toothless,
336 HERPETOLOGICA [Vol. 67, No. 3
pointed; maxillary teeth 14 (including four
empty sockets), recurved, subequal in length;
large flange projecting medially at approxi-
mately level of middle of maxilla; posterior end
of maxilla tapers to blunt point. Anterior end of
ectopterygoid single, not expanded.
Variation.—This section is based on the
examination of the 16 paratypes; however, a
male specimen with an incomplete tail was
excluded from the subcaudal and total seg-
mental counts. The description of color in life
is based, in part, on an additional specimen
referred to the new species (see below).
Scalation: Nuchal scales separating posteri-
or temporals four to six, X
¯54.9 (four, in 2
specimens; five, in 13 specimens; six, in 1
specimen); infralabials (on one side) six to
eight, X
¯57.3 (six, 4 counts; seven, 15 counts;
eight, 13 counts); second pair of chin shields
in medial contact with each other and sepa-
rated by one midgular scale in eight speci-
mens each; midgular scales two to three, X
¯5
2.6 (two, in 6 specimens; three, in 10 speci-
mens); ventrals 133–139, X
¯5136.6, n55in
females; 130–137, X
¯5133.5, n511 in males;
subcaudals 29–31, X
¯530.0, n55 in females;
34–39, X
¯536.7, n510 in males; total
segmental counts 164–168, X
¯5166.6, n55
in females; 168–176, X
¯5170.5, n510 in
males.
Color pattern (in preservative): Color pat-
tern bicolor, composed of dark and pale areas
disposed as follows: pattern of head and nape
in dark grayish brown (20) and pale horn (92)
as in holotype in all specimens; dorsal and
lateral pattern of body and tail polymorphic:
usually uniformly dark grayish brown (20)
except for first dorsal scale row (i.e., similar to
that of holotype) in nine specimens; mostly
composed of dark (usually dark grayish brown
or 20) middorsal marks (usually one stripe on
anterior end of body, followed posteriorly by
roughly rhomboidal blotches and then narrow
transverse bands) on pale background (usually
buff or 124, somewhat darkened in some
specimens) in remaining seven specimens;
ventral pattern as that of holotype in all
specimens.
Color pattern of head and nape: Notewor-
thy variation included presence or absence of
pale mottling on dorsal half of head, width of
pale nuchal collar, and presence or absence of
dark mottling on ventral half of head. Pale
mottling on first, second, and fourth supra-
labials and right loreal and postnasal in one
specimen; on first to fourth supralabials (except
for right second supralabial), postnasals, and
prefrontals in another one; absent in remaining
specimens. Pale collar on posterior end of head
and anterior end of nape in all specimens
(darkened in one large male, MZFC 25528,
SVL 5200 mm), its anterior margin extending
across midline between levels of about one-
half and five-sixths length of parietal, curving
anteriorly, parallel to posterolateral contour of
parietals, to between levels of posterior margin
of postoculars and about two-thirds length
of parietal-primary temporal common suture;
then laterally and ventrally, reaching upper lip
between levels of anterior margin of fifth su-
pralabials and one-third length of sixth supra-
labials (pale edge clear-cut on dark primary
temporals and supralabials in about one-half of
specimens; rendered irregular or discontinu-
ous by pale mottling on these, and often
adjacent, scales in remaining specimens),
its posterior margin extending across midline
between levels of one-half length of first medial
nuchal and posterior end of second medial
nuchal, then slightly posteroventrally between
levels of one-half lengths of second and third
scales posterior to last supralabials and in-
fralabials; pale medial projection extending
anteriorly from anterior margin of collar to
posterior end of frontal in two specimens; dark
scattered spots occasionally on nuchals. Men-
tal, infralabials, and chin shields immaculate
or with few, scattered dark specks in seven
specimens; immaculate except for slight dark
mottling on first, third, and fourth infralabials
in one specimen; mental and first to third
infralabials (or most of them) roughly uniform-
ly dark; remaining infralabials and chin shields
with moderate dark mottling, in two specimens;
mental and at least first to fifth infralabials, and
often sixth and/or seventh infralabials (on one
or both sides), roughly uniformly dark or with
slight pale mottling; remaining infralabials and
chin shields immaculate or with moderate dark
mottling, in remaining six specimens.
Color pattern of body and tail (mostly uni-
color specimens): dorsal scale rows of body
uniformly dark except for scales of first row on
anterior fifth or fourth of body, anterior half of
September 2011] HERPETOLOGICA 337
body, and throughout length of body with pale
middle or mid-posterior spot in three speci-
mens each. Dorsal scale rows of tail uniformly
dark in seven specimens; all dorsal scales with
dark margins and small, irregular, middle pale
spot in two specimens; subcaudals immaculate
except for dark lateral margins in two speci-
mens; immaculate except for dark lateral mar-
gins and few, scattered dark speckles, more
abundant posteriorly and mainly concentrated
along midline, in five specimens; all subcau-
dals dark-speckled; speckling gradually heavi-
er posteriorly, covering more than anterior
half of each scale on posterior end of tail, in
two specimens.
Color pattern of body and tail (striped/
blotched/banded specimens, Fig. 2): dark poste-
rior border of nuchal collar abruptly narrowing
posteriorly, forming funnel-shaped mark on
nape, in all specimens; funnel-shaped mark
followed posteriorly by dark (blackish neutral
gray or 82), small middorsal blotches about as
wide as long to slightly wider than long on
anterior third of body; gradually becoming
narrow, moderately elongated transverse bands
on rest of body (background color somewhat
darkened pale horn or 92) in MZFC 22160;
funnel-shaped mark extending posteriorly into
dark middorsal field on five or six middorsal scale
rows in remaining specimens; middorsal field
consisting of narrow transverse bands connected
medially to each other (occasionally separated)
throughout body in MZFC 22170; middorsal
field composed of narrow transverse bands
connected medially to each other for about three
head lengths, gradually becoming separated
posteriorly on rest of body (consecutive bands
often connected to each other by oblique lines in
zigzag pattern) in MZFC 25551; middorsal field
consisting of straight stripe extending on about
anterior one-fourth of body, followed posteriorly
by slightly wider than long, irregular blotches
connected to each other by oblique lines in zigzag
pattern to nearly mid-body; mostly separated on
rest of body, in MZFC 25552; middorsal field
consisting of straight stripe extending to about
mid-body, followed posteriorly by irregular,
small, about as wide as long blotches separated
or connected to each other by oblique lines in
zigzag pattern; gradually becoming narrow trans-
verse bands on posterior end of body, in MZFC
22162; middorsal field short, composed of two
overlapped rhombs, followed posteriorly by
irregular, wider-than-long blotches, first connect-
ed medially to each other, then gradually
becoming separated; blotches gradually becom-
ing narrow, oblique, then transverse bands
posteriorly (background color considerably dark-
ened, rendering dark marks inconspicuous) in
MZFC 22168; middorsal field composed of
overlapped rhombs, gradually becoming sepa-
rate, transversally elongated posteriorly on ante-
rior third of body, followed posteriorly by
irregular blotches connected medially to each
other to about level of mid-body, gradually
becoming separate, narrow transverse bands on
posterior half of body in MZFC 22167. Middor-
sal transverse bands narrow; one-scale wide in
two specimens, one- to two-scales wide in
remaining specimens; pale intervals between
transverse bands usually as wide as they are.
Scales in first three dorsal rows of body with
middle pale spot throughout body in six speci-
mens; spots large in first row (scales mostly pale),
smallinsecondandthirdrows(scalesmostly
dark) in three specimens; spots rather large,
similar in size, in first three rows (dorsal margin
ofscalesinthirdrowofteninvolvedinmiddorsal
dark blotches or bands, or pale intervals between
them) in remaining three specimens; scales in
first and second dorsal rows with large, pale
middle spot, encircled entirely by narrow dark
margins except dorsally on scales in second row
in one specimen.
Dark, narrow, middorsal transverse bands
on anterior end to anterior half of tail, grad-
ually merging with each other posteriorly,
rendering posterior end of tail uniformly dark
in five specimens; dorsal scales dark, most
with pale middle spot that gradually becomes
smaller posteriorly in one specimen; dark,
short middorsal stripe bordered laterally by
pale areas on anterior end of tail, gradually dis-
appearing posteriorly in one specimen; scales
of first dorsal row with pale middle spot
throughout length of tail in six specimens, on
anterior half of tail in one; subcaudals immac-
ulate except for dark streak on lateral margins
and few, dark scattered speckles, more abun-
dant posteriorly and mainly concentrated along
midline, in all specimens.
Color in life: No photographs or notes of
color in life of the holotype were available.
However, in a color photograph of a paratype
338 HERPETOLOGICA [Vol. 67, No. 3
predominantly dark dorsally and laterally in
preservative (MZFC 22163), the dorsal and
lateral color is uniform and most similar to
cobalt blue (168), except for the nuchal collar,
which is most similar to rose (9; Fig. 3). In a
color photograph (not shown) of two para-
types predominantly dark dorsally and later-
ally in preservative (numbers not recorded),
the dorsal and lateral color also is approxi-
mately cobalt blue (168), uniform except for
the nuchal collar, which is most similar to
spinel red (108B) in one specimen and pale
horn (92) in the other one. In a color photo-
graph of an additional banded specimen of G.
occabus from El Molote, not included in the
description above (MZFC uncatalogued; field
number JCBH 651), the dark color of the
dorsal and lateral surfaces of the head and
middorsal marks on the body and tail is dusky
brown (19), whereas the color of the nuchal
collar and background of all but the first
dorsal rows is geranium (12) to scarlet (14),
and the background color of the first dorsal
row and venter is pale horn (92; Fig. 3).
Etymology.—The specific name comes from
the Latin word occabus, meaning collar, in
reference to the light nuchal collar present in
all known specimens of this species.
Distribution and ecology.—Geophis occa-
bus is known only from the type locality and
vicinity in the western portion of the Sierra
Madre del Sur of Guerrero between 1787 m
and 2014 m of elevation, and appears to be
allopatric to other species of the sieboldi
group (Fig. 4). The closest Geophis records
to G. occabus are those of G. omiltemanus,
from Omilteme (5Omiltemi), Guerrero, and
of a specimen of Geophis from Amula, Guer-
rero, assigned likely in error to G. sieboldi (see
below) by Downs (1967). Both are about 72 km,
straight line, from the type locality of G.
occabus. The closest records of species in the
sieboldi group, excluding the Amula specimen,
to the type locality of G. occabus are those of G.
russatus and G. laticollaris from the region
of Putla in southwestern Oaxaca (Smith and
Williams, 1966); G. petersii from Pa
´tzcuaro,
central Michoaca
´n, and Me
´xico City (Downs,
1967); G. pyburni from Dos Aguas, eastern
Michoaca
´n (Campbell and Murphy, 1977); G.
sieboldi, from Coalcoma
´n, eastern Michoaca
´n
(Downs, 1967); and G. sallei, from the Santa
Catarina Juquila region in southern Oaxaca (L.
Canseco-Ma
´rquez, personal communication).
The region of El Molote is found in an
elevational gradient (1300–2500 m) character-
ized by the presence of acute peaks and
precipitous slopes with narrow gullies and few
plains, and covered by numerous permanent
streams that flow into the Atoyac and Coyuca
rivers, whose basins belong to the Costa
Grande hydrologic region (Lozada et al.,
2003). Because there are no nearby climato-
logical stations, reported climate for the re-
gion may not be accurate. Whereas INEGI
(1996) reports a semiwarm, humid climate
with abundant rain in the summer and a
temperate, subhumid climate with rain in the
summer for the lowest and highest elevations
in the region, respectively, the climate for the
1300–2000 m of elevation belt in the state of
Guerrero, and especially in the northeastern
FIG. 3.—Geophis occabus in life. Left: MZFC 22163; right: MZFC uncatalogued (field number JCBH 651). See text
for details.
September 2011] HERPETOLOGICA 339
extreme of the Costa Grande hydrologic re-
gion, is regarded as semiwarm and subhumid,
with a mean annual temperature between
18uC and 22uC and an annual precipitation
gradient from 900 to 1100 mm by Meza and
Lo
´pez (1997).
Original vegetation at El Molote is cloud
forest, although most of it has been replaced by
coffee plantations. In less disturbed places, the
forest is dense, with the canopy reaching 25–
30 m in height; Pinus ayacahuite,P. strobus
var. chiapensis, and Ulmus mexicana are
emergent species, and Alfaroa costaricensis,
Sloanea sp., Quercus salicifolia,Cojoba ar-
borea,Magnolia schiedeana, and Zanthoxylum
melanostictum are dominant species (Lozada
et al., 2003).
DISCUSSION
Assignment of G. occabus to the sieboldi
group seems straightforward, except most
species in the group exhibit apical pits, which
apparently are absent in G. occabus. Although
it is difficult to be certain that apical pits are
absent in a particular species of Geophis
(Downs, 1967), if apical pits are present in
G. occabus, they are certainly inconspicuous,
which is unusual for a species with strongly
keeled dorsals (Downs, 1967). Apical pits have
not been reported in G. petersii (Downs,
1967); thus, their apparent absence in
G. occabus does not modify Downs’ (1967)
definition of the group. At any rate, it should
be noted that the monophyly of Downs’
(1967) groups has not been investigated.
Geophis sieboldi was described by Jan
(1862) from four syntypes: two from ‘‘Mexi-
co,’’ one from ‘‘Guadalupa,’’ and one from an
unspecified locality. Unfortunately, the syn-
types, deposited at the Milano museum, were
destroyed in World War II (Conci, 1967) and
the other syntypes are currently lost (M.
Franzen, F. Glaw, and H. Grillitsch, personal
communication). In his monograph of the
genus, Downs (1967) assigned seven other
specimens to G. sieboldi: five without locality
data, one from Amula, Guerrero, and one
from Coalcoma
´n, Michoaca
´n. Downs (1967)
noted that the specimen from Amula (BMNH
90.4.24.12), a juvenile male with a SVL of
136 mm, differed from both the syntypes of G.
sieboldi and the rest of his specimens in two
characters. First, the specimen from Amula
had 132 ventrals and 39 subcaudals, whereas
the two probably male syntypes had 146–151
ventrals and 37–38 subcaudals, and his other
FIG. 4.—Geographic distribution of Geophis occabus and geographically closest species of the sieboldi group.
Discontinuous lines represent state limits. The solid circle represents the type locality of G. occabus. The open circle,
open triangle, solid triangle, inverted triangle, open square, and solid square represent other species of the sieboldi
group (G. laticollaris,G. pyburni,G. sieboldi, G. petersii,G. russatus, and G. sallei, respectively). The question mark
represents the population of Geophis from Amula, Guerrero.
340 HERPETOLOGICA [Vol. 67, No. 3
four males had 143–147 ventrals and 37–42
subcaudals. Thus, the ventral count in the spec-
imen from Amula was 11 lower than that of
any other male assigned to G. sieboldi. The
sum of ventrals and subcaudals (171) in the
specimen from Amula also was 10 lower than
that of any other specimen of either sex
assigned to G. sieboldi. Second, the specimen
from Amula had a distinct light collar involv-
ing the posterior part of the parietals, supra-
labials 5 and 6, and the first row of scales
behind the head, whereas a collar was not
mentioned in the original description of the
species (although the smallest syntype had a
SVL of 126 mm). Only faint traces of a collar
were discernable in one of the specimens (SVL
5142 mm) examined by Downs, and a collar
was absent in a slightly larger specimen (SVL 5
146 mm) and all of his remaining adults.
Therefore, three facts suggest that the Amula
specimen might represent G. occabus. First,
the ventrals and subcaudals counts in the
specimen from Amula are similar to the counts
in the type series of G. occabus. Second, all
of the specimens of G. occabus have a distinct
light nuchal collar. Third, Amula is about
74 km from the type locality of G. occabus.
Additional material from the Amula population
is needed to confidently establish its taxonomic
identity.
Geophis occabus has been included in
molecular phylogenetic analyses that encom-
pass about two-thirds of all representatives
of the genus sequenced for the mitochon-
drial gene cytochrome b (1116 base pairs; L.
Canseco-Ma
´rquez, personal communication).
Results of a Bayesian analysis of these se-
quences show that all of six sequences of G.
occabus, whether from predominantly dark or
banded specimens, form a strongly supported
clade (posterior probability value 51.0) and
are nearly identical: the average uncorrected
genetic distance among these sequences was
0.0017%, about one-tenth of the uncorrected
genetic distance between G. occabus and its
sister species (0.019%).
Geophis occabus represents the first Mexi-
can species reported to exhibit both a unicolor
and a bicolor body and tail dorsal patterns,
a polymorphism similar to that documented
previously in three lower Central American
species of the sieboldi group (G. brachycepha-
lus,G. talamancae, and G. tectus; Savage and
Watling, 2008). However, whereas the bicolor
pattern in G. occabus is composed of dark
markings (middorsal stripe/spots/blotches/trans-
verse bands) on a red background color, the
bicolor patterns in the lower Central American
species consist of red stripes, spots, blotches, or
bands (likely red in G. tectus) on a black back-
ground color. It has been suggested that the
latter patterns are ‘‘at least incipient mimictic
patterns,’’ but this suggestion has not been
corroborated (Savage and Watling, 2008).
A potential source of taxonomic confusion,
associated with color pattern polymorphism in
Geophis,isthatthispolymorphismmaygo
undetected in species descriptions on the basis
of exceedingly small samples. As a consequence
of this unawareness, different color morphs of
the same species may be erroneously described
as different species. On the basis of our knowl-
edge of the dorsal color pattern polymorphism
in G. occabus, we suggest that this may have
been the case with the poorly known G.
laticollaris and G. russatus (a close relative
of G. occabus; L. Canseco-Ma
´rquez, personal
communication). Geophis laticollaris and G.
russatus exhibit dorsal color patterns that are
essentially identical to the unicolor and bicolor
dorsal patterns, respectively, found in G.
occabus. All of the types of G. laticollaris (one
specimen) and G. russatus (two specimens)
were collected in the vicinity of Putla, Oaxaca.
In addition, Downs (1967) stated that all of
these specimens had ‘‘the form and scutella-
tion of G. sallei.’’ Nonetheless, he placed G.
laticollaris in the synonymy of G. sallei,aspe-
cies with a unicolor ‘‘grayish-brown to brown-
ish-black’’ dorsum (a decision later reversed by
Smith and Chiszar, 1992), but regarded G.
russatus as specifically distinct from G. sallei
because of the ‘‘distinctive pattern’’ of G.
russatus and because this pattern occurred ‘‘in
sympatry with typical sallei.’’ Thus, it appears
that the potential conspecificity of G. laticollaris
and G. russatus is an issue that requires further
investigation, and that the knowledge of the
color pattern polymorphism in G. occabus
might shed light on the taxonomy of other
species of Geophis.
Acknowledgments.—This paper is based in part upon
work supported by a grant to AN-MdO from the
Direccio
´n General de Apoyo al Personal Acade
´mico,
September 2011] HERPETOLOGICA 341
Universidad Nacional Auto
´noma de Me
´xico (PAPIIT IN
224009). We thank L. Canseco-Ma
´rquez for his valuable
comments on this manuscript and for sharing his findings;
I. Dura
´n-Fuentes for field assistance; M. Franzen and F.
Glaw, H. Grillitsch, and S. Scali for searching for the
Munich, Vienna, and Milano syntypes of Geophis sieboldi,
respectively; E. Pe
´rez-Ramos for cataloguing material in
the MZFC; L. L. Romero-Salas for taking the photograph
in Fig. 2, and J. F. Schmidtler and J. H. Townsend for
providing relevant literature.
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.Accepted: 20 May 2011
.Associate Editor: Bryan Stuart
APPENDIX I
Specimens Examined
Taxa are presented in alphabetical order. ANMO is an
abbreviation for field numbers of uncatalogued specimens
being deposited in the MZFC.
342 HERPETOLOGICA [Vol. 67, No. 3
Geophis omiltemanus: MEXICO: GUERRERO: Mu-
nicipio Chilpancingo de Los Bravo, Omiltemi (MZFC
4125).
Geophis russatus: MEXICO: OAXACA: Municipio Santa
Marı
´a Yucuhuiti: Miramar, desviacio
´n a San Pedro Simiyubi,
16u59955.40N, 97u47953.20W, elevation 1756 m (ANMO
1973); carretera Miramar-Llano Grande, 16u59946.40N,
97u47945.60W, elevation 1747 m (ANMO 1974).
Geophis sallaei: MEXICO: OAXACA: Municipio
Santa Catarina Juquila; carretera Rı
´o Grande-Juquila,
16u11928.1-N, 97u18927.10W (ANMO 2026); Municipio
Pluma Hidalgo (MZFC 22615).
September 2011] HERPETOLOGICA 343
