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A New Species of Snake of the Geophis sieboldi Group
(Squamata: Dipsadidae) from Estado de México, Mexico
Authors: Barragán-Reséndiz, Lesly Montserrat, Pavón-Vázquez,
Carlos J., Cervantes-Burgos, Romina Itzel, Trujano-Ortega, Marysol,
Canseco-Márquez, Luis, et al.
Source: Herpetologica, 78(4) : 268-276
Published By: The Herpetologists' League
URL: https://doi.org/10.1655/Herpetologica-D-22-00011
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Herpetologica, 78(4), 2022, 268–276
Ó2022 by The Herpetologists’ League, Inc.
A New Species of Snake of the Geophis sieboldi Group (Squamata: Dipsadidae) from
Estado de M ´
exico, Mexico
LESLY MONTSERRAT BARRAGA
´N-RES ´
ENDIZ
1
,CARLOS J. PAV ´
ON-VA
´ZQUEZ
2
,ROMINA ITZEL CERVANTES-BURGOS
1
,
MARYSOL TRUJANO-ORTEGA
1,3
,LUIS CANSECO-MA
´RQUEZ
3
,AND URI OMAR GARC´
IA-VA
´ZQUEZ
1,4
1
Laboratorio de Sistema
´tica Molecular, Carrera de Biolog´
ıa, UMIEZ, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Aut ´
onoma de
M´
exico, Batalla 5 de mayo s/n, Ej ´
ercito de Oriente, Ciudad de Mexico 09230, M´
exico
2
Department of Biology, University of Kentucky, Lexington, KY 40506, USA
3
Departamento de Biolog´
ıa Evolutiva, Museo de Zoolog´
ıa, Facultad de Ciencias, Universidad Nacional Aut ´
onoma de M´
exico, AP.70-399 Mexico,
Ciudad de Mexico 04510, M´
exico
ABSTRACT: We describe Geophis berillus sp. nov., a new species of the Geophis sieboldi group based on three specimens from the Valle de
Bravo region in the Trans-Mexican Volcanic Belt, Estado de M´
exico, Mexico. The new species differs from all other members of this group by
having 17 dorsal scale rows without apical pits, 149 and 151–152 ventrals (in males and females, respectively), and the lower portion of each scale
in the first dorsal scale row pale. The new species is allopatric respective to other Geophis species. A phylogenetic analysis based on mitochondrial
DNA (cyt-b) supports the inclusion of G. berillus sp. nov. in the G. sieboldi group and a sister relationship with G. sieboldi, a finding corroborated
by morphological evidence.
Key words: Description; Endemic; Pine forest; Semifossorial; Taxonomy; Trans-Mexican Volcanic Belt
THE DIPSADID genus Geophis Wagler 1830 contains 53
recognized species, making it one of the largest genera of
colubroid snakes in the Western Hemisphere (Gr ¨unwald et
al. 2021a,b; Palacios-Aguilar et al. 2022). The genus extends
from the Sierra Madre Occidental in southern Tamaulipas,
Mexico, south and east through central and southern Mexico
and Central America to northern and western Colombia
(Wilson and Townsend 2007; Savage and Watling 2008;
Garc´
ıa-Cobos et al. 2020).
Downs (1967) divided Geophis into seven species groups
(G. chalybeus,G. championi,G. dubius,G. latifrontalis,G.
omiltemanus,G. semidoliatus, and G. sieboldi) based on
their external morphology. Besides the description of new
species in each of these groups, the richness of the genus was
recently increased by the inclusion of G. annuliferus,G.
sartorii (both previously in Tropidodipsas), and G. sanniolus
(previously in Sibon;Gr¨unwald et al. 2021a).
The G. sieboldi group is composed of 17 species and is
defined by numerous morphological characters, as follows:
dorsal scales in 15 or 17 rows, keeled at least above the vent;
paired apical pits present; head moderately distinct from
neck or not; snout long, projecting well beyond lower jaw;
eye small to moderate; rostral not produced posteriorly
between internasals; prefrontals and loreals elongate;
parietals short, broad; anterior temporal absent; ventrals
118–151 in males, 118–154 in females; subcaudals 28–51 in
males, 23–43 in females; and tail/body length ratio 14.1–21.2
in males and 11–17.6 in females. In addition, Downs (1967)
defined the G. sieboldi group by several dentition characters,
as follows: maxilla extends anteriorly to suture between
supralabials 2 and 3; anterior extension about equal to that of
palatine; maxilla dorsoventrally compressed; in lateral view,
posterior third of maxilla curves ventrally; anterior tip of
maxilla toothless (first tooth at tip of maxilla or preceded by a
short toothless area in G. zeledoni Taylor 1954), pointed; 8–
15 maxillary teeth; anterior end of ectopterygoid single, not
expanded; and postorbital bone narrow.
The G. sieboldi group has the most widespread distribution
in the genus, ranging from Jalisco and Guanajuato states
(Mexico) to northwestern Colombia, and is the only group of
Geophis present in South America (Downs 1967; Garc´
ıa-Cobos
et al. 2020). The following seven species of the G. sieboldi
group are known from Mexico: G. laticollaris Smith, Lynch and
Altig 1965 from eastern Guerrero and western Oaxaca
(Palacios-Aguilar et al. 2022); G. nasalis Cope 1868 from the
Pacific versant of Chiapas (Pav ´
on-Va
´zquez et al. 2011); G.
occabus Pav´
on-Va
´zquez et al. 2011 from central Guerrero,
Mexico (Pav´
on-Va
´zquez et al. 2011; Palacios-Aguilar and
Santos-Bibiano 2016); G. petersii Boulenger 1894 from Jalisco,
Colima, Guanajuato, Ciudad de M´
exico, northern Guerrero,
and Michoaca
´n (CONANP 2006; Ponce-Campos and Flores-
Villela 2007; Pav ´
on-Va
´zquez et al. 2011; Carmona-Torres and
Gonza
´lez-Herna
´ndez 2014; Mu ˜
noz-Nolasco et al. 2015; Cruz-
Sa
´enz et al. 2017; Leyte-Manrique et al. 2018); G. pyburni
Campbell and Murphy 1977 from Colima and western
Michoaca
´n(Pav
´
on-Va
´zquez et al. 2011; Monta ˜
no-Ruvalcaba
et al. 2020); G. sieboldi Jan 1862 from Colima, southern Jalisco,
and western Michoaca
´n(Pav
´
on-Va
´zquez et al. 2011; Ahumada-
Carrillo et al. 2014); and G. sallei Boulenger 1894 from south-
central Oaxaca (CONABIO 2009; Pav ´
on-Va
´zquez et al. 2011).
Here, we describe a new species of the G. sieboldi group
from the central mountains of Estado de M ´
exico based on
three specimens. The specimens show a unique combination
of characters and are apparently allopatric with respect to
closely related species of Geophis (see comparison section).
Thus, we conclude that they represent a new species and
describe it below.
MATERIALS AND METHODS
Morphological Comparisons
As part of an ecological study of the local amphibians and
reptiles, field work was conducted between June 2015 and
4
CORRESPONDENCE: email, urigarcia@gmail.com
268
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August 2016 (Cervantes-Burgos 2017). Three specimens of
Geophis sp. from the Valle de Bravo region were euthanized
and fixed in 10% buffered formalin, subsequently transferred
to 70% ethanol for permanent storage, and deposited in the
herpetological collection of the Museo de Zoolog´
ıa de la
Facultad de Ciencias, Universidad Nacional Aut ´
onoma de
M´
exico (MZFC-HE), and Museo de Zoolog´
ıa de la Facultad
de Estudios Superiores Zaragoza, Universidad Nacional
Aut´
onoma de M´
exico (MZFZ). The three individuals of
Geophis from the Valle de Bravo region were compared with
specimens of species in the G. sieboldi group, including the
type series of G. occabus. We provide a list of the specimens
examined in the Appendix.
Scale counts were performed by using a dissecting
microscope. Ventrals were counted as suggested by Downs
(1967). Measurements were taken with calipers to the
nearest 0.1 mm. All scale dimensions were measured at
their maximum. Head length was measured from the tip of
the snout to the posterior end of the parietals. Bilateral
characters were scored on both sides. When the condition 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 (/). Color descriptions and codes follow
K¨
ohler (2012). The diagnosis was based on the specimens
examined and relevant literature (Downs 1967; Kofron 1988;
Nieto-Montes de Oca 2003; Wilson and Townsend 2007;
Pav´
on-Va
´zquez et al. 2011, 2013; Palacios-Aguilar et al.
2022). The description of dentition characters is based on
the right maxilla and the associated ectopterygoid of the
holotype. Finally, the right hemipenis of the preserved
holotype was extracted, described, and preserved following
Zaher and Prudente (2003) and Sales-Nunes (2011).
Molecular Data Collection
We obtained fragments of the mitochondrial DNA
(mtDNA) gene coding for cytochrome b (cyt-b) for G.
petersii,G. laticollaris,G. sallei,G. sieboldi, and the type
series of the new species (Table 1). We extracted the
genomic DNA from liver or muscle tissue with the use of a
standard ammonium acetate protocol (Fetzner 1999) and
used polymerase chain reaction (PCR) to amplify the
aforementioned fragment with primers L14919/H15716
and L15845/H16064 (Burbrink et al. 2000). PCR cycle
parameters consisted of an initial denaturation cycle at 948C
for 7 min followed by 40 cycles of denaturation at 948C for
40 s, primer annealing at 45–508C for 30 s, and extension at
728C for 1 min, and a final extension cycle at 728C for 7 min
(Burbrink et al. 2000). We purified PCR products with
polyethylene glycol (Lis 1980). Purified DNA was sequenced
by Macrogen Korea (Standard-Seq de Macrogen Inc.). We
also obtained cyt-b sequences from GenBank of G. occabus
and representative species from other Geophis species
groups such as G. godmani Boulenger 1894; G. juarezi
Nieto-Montes de Oca 2003; G. carinosus Stuart 1941; G.
turbidus Pav´
on-Va
´zquez, Canseco-Ma
´rquez and Nieto-
Montes de Oca 2013; G. dubius (Peters 1861); and G.
latifrontalis Garman 1883; as well as Rhadinaea flavilata
(Cope 1871), which was used as the outgroup (Table 1).
Phylogenetic Analyses and Genetic Divergence
We edited the sequences using Sequencher v4.1.4 (Gen
Codes Corporation, Ann Arbor, MI). The alignment was
performed using the Muscle algorithm included in the
software MEGA7 (Kumar et al. 2016). We obtained the best-
fitting substitution models and partitioning scheme simulta-
neously using the Bayesian Information Criterion in the
software PartitionFinder v2.1.1 (Lanfear et al. 2017). The
initial partitioning scheme was based on codon positions. We
performed a partitioned maximum likelihood phylogenetic
analysis in RAxML v1.3 (Silvestro and Michalak 2012) under
the GTR GAMMA model. Support values were obtained by
performing 3000 rapid bootstrap replicates. Additionally, we
performed a Bayesian phylogenetic analysis with the
software MrBayes v3.2 (Ronquist et al. 2012). We ran the
analysis for 30,000,000 generations with the default settings
and tree sampling every 3000 generations. We evaluated the
results for convergence and enough sampling in Tracer v1.6
(Rambaut et al. 2014), and we combined the trees obtained
in each run by using LogCombiner v1.8.4 (Drummond et al.
2012). The maximum clade credibility tree was annotated in
TreeAnnotator v1.8.4 (Drummond et al. 2012) after
specifying a burn-in of 25%. Nodes with a bootstrap support
value (BS) of 70 and a posterior probability (PP) of 0.95
were considered significantly supported (Huelsenbeck and
Rannala 2004). Finally, we calculated the corrected pairwise
genetic distances using the KP2 model with MEGA7 (Kumar
et al. 2016).
TABLE 1.—Samples used in phylogenetic analyses. ANMO, LCM, and RWB are abbreviations for field numbers of uncatalogued specimens being
deposited in the MZFC-HE.
Species Voucher GenBank accession Locality
Geophis berillus sp. nov. MZFC-HE 35651 OP490303 Rancho el Pinalito, Valle de Bravo, Estado de Mexico.
Geophis berillus sp. nov. MZFZ 4404 OP490304 Road to San Lucas del Pulque, Temascaltepec, Estado de Mexico.
Geophis berillus sp. nov. MZFZ 4405 OP490305 Road to San Lucas del Pulque, Temascaltepec, Estado de Mexico
G. carinosus MZFC-HE 10552 KC917314.1 Rancho Primero de Mayo, 12.3 km NE Tapalapan, Veracruz, Mexico.
G. dubius MZFC-HE 27256 KC917319.1 4 km SE San Isidro Buenos Aires.
G. godmani CASHERP 178126 JQ598932.1 Provincia de Puntarenas, Costa Rica.
G. juarezi MZFC-HE 27525 KC917315.1 Municipality of Santiago Comaltepec, Sierra de Jua
´rez, Oaxaca, Mexico.
G. latifrontalis RWB 7232 KC917322.1 San Joaqu´
ın, Quer´
etaro, Mexico.
G. occabus MZFC-HE 25528 KC917323.1 Municipality of Atoyac de ´
Alvarez, El Molote, Guerrero, Mexico.
G. petersii CNARIBH 24550 OP490306 Municipality of Tuxpan, Las Antenas, Guerrero, Mexico.
G. laticollaris ANMO 1973 OP490307 Ejido Miramar, deviation to San Pedro Siniyuvi, Oaxaca, Mexico.
G. sallei LCM 1285 OP490308 San Francisco Coatla
´n, Oaxaca, Mexico.
G. sieboldi MZFC-HE 27269 OP490309 Highway from Chiapas to Nuevo Naranjal, 7 km N de El Chivato Colima, Mexico.
G. turbidus MZFC-HE 27254 KC917321.1 Municipality of Cuetzalan, 3.5 O Xocoyolo, Puebla, Mexico.
R. flavilata CASHERP 198634 AF471078.1 Lake Laural, Florida, USA.
269
BARRAGA
´N-RES ´
ENDIZ ET AL.—NEW SPECIES OF THE GEOPHIS SIEBOLDI GROUP
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RESULTS
The final alignment of the sequenced mitochondrial
fragment included 1098 bp. The partitioning scheme of the
mtDNA proposed by PartitionFinder v2.1.1 included three
partitions, one for each codon position of cyt-b. The
substitution model used for the Bayesian analysis was
GTRþIþG for all partitions.
The maximum likelihood and the Bayesian analyses
yielded similar topologies with differences only in weakly
supported nodes (Fig. 1). Both phylogenetic hypotheses
indicate that the Geophis population from the Valle de Bravo
belongs to the G. sieboldi group (Fig. 1). The phylogeny
shows that the G. sieboldi group is monophyletic, but the
inclusion of G. petersii within the group is not strongly
supported. The three specimens of the Geophis population
from the Valle de Bravo formed a strongly supported clade
that is sister to G. sieboldi (BS ¼100, PP ¼0.999). The
mean genetic distance between specimens of Geophis sp. is
0.007, while the mean genetic distance with G. sieboldi is
0.026.
Our morphological examination and phylogenetic hypoth-
eses showed that the sample from Valle de Bravo is
assignable to the G. sieboldi group and morphologically
distinguishable from the closely related G. sieboldi and the
other species in the group (Table 2). Furthermore, the
population of Geophis from the Valle de Bravo and G.
sieboldi are allopatric, reciprocally monophyletic, and
moderately genetically divergent from each other. On the
basis of these results, we consider that the sample of Geophis
from the Valle de Bravo represents a new species, which we
name and describe below.
SPECIES DESCRIPTION
Geophis berillus sp. nov.
(Figs. 2–3A)
Holotype (Fig. 2–3A).—MZFC-HE 35651 (Field Num-
ber UOGV 2723), an adult male from Rancho el Pinalito,
municipality of Valle de Bravo, Estado de M ´
exico, Mexico
(19.09238N, 100.080288W; datum WGS84 in all cases),
2,328-m elevation, collected by M. Trujano-Ortega and
U.O. Garc´
ıa-Va
´zquez on 19 June 2015.
Paratypes.—A juvenile female and an adult female
(MZFZ 4404–4405) from the road to San Lucas del Pulque,
FIG. 1.—Maximum likelihood tree based on sequences of the partial mitochondrial gene cytochrome b (cyt-b). Circles indicate nodes that were strongly
supported by the maximum likelihood (white) and Bayesian (black) analyses. A color version of this figure is available online.
270 Herpetologica 78(4), 2022
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municipality of Temascaltepec, Estado de M ´
exico, Mexico
(19.09818N, 100.04558W), 2,272-m elevation, collected by
R.I. Cervantes-Burgos, D. Garc´
ıa-Morales, D. Rivera, and
A.E. Valdenegro-Brito in July–August 2016.
Diagnosis.—Geophis berillus sp. nov. is distinguished by
having the fifth supralabial and parietal in contact; keeled
dorsal scales, lacking apical pits, arranged in 17 rows; 149
ventrals (n¼1) in males and 151–152 (n¼2) in females; a
uniformly dark nuchal region; and the lower portion of each
scale in the first dorsal scale row pale.
Comparisons (Table 2).—Geophis berillus sp. nov. may
be distinguished from all species in the G. championi and G.
semidoliatus groups, most species in the G. sieboldi group
(except G. dunni,G. nasalis,G. occabus, and G. sieboldi), G.
annuliferus,andG. sanniolus by having dorsal scales
arranged in 17 rows versus 15 in the other species. Geophis
berillus sp. nov. may be distinguished from the species in the
G. chalybeus and G. latifrontalis groups and most species in
the G. dubius group (except G. carinosus,G. juarezi, and G.
turbidus) by having strongly keeled dorsal scales above the
vent (dorsal scales smooth or faintly keeled above vent) and
from G. carinosus,G. juarezi, and G. turbidus by having
TABLE 2.—Selected characters in the species of the G. sieboldi group distributed in Mexico.
Character G. berillus G. laticollaris G. nasalis G. occabus G. petersii G. pyburni G. sallaei G. sieboldi
Dorsal scales 17 15 17 17 15 15 15 17
Ventral scales (male) 149 118–129 115–130 130–137 140–158 128–130 118–129 143–147
Ventral scales (female) 151–152 127–133 118–142 133–139 145–148 130–139 127–133 147–153
Subcaudal scales (male) 43 33–41 29–37 34–39 34–38 31–33 32–41 37–42
Subcaudal scales (female) 33–34 26–36 23–33 29–31 29–38 27–32 26–36 34–38
Keeled scales Around the
vent
Posterior region
of the body
Except in
the neck
Posterior 3/4
of the body
Around the
vent
Around the
vent
Except in
the neck
Posterior region
of the body
Apical pits Absent Present Present Absent Absent Present Present Present
Nuchal collar Absent Present Absent Present Absent Absent Absent Absent
Hemipenial spinules 14 22 25 – 4 4 – 20
Maxillary teeth 12 12 11–13 14 6 14 – 11–14
FIG. 2.—Geophis berillus sp. nov., head of holotype (MZFC-HE 35651)
in dorsal view (top), ventral view (middle), and left lateral view (bottom).
The horizontal bars represent 5 mm. A color version of this figure is available
online.
FIG. 3.—Comparison of Geophis berillus sp. nov. and its sister species, G.
sieboldi (in life). (A) Holotype of G. berillus sp. nov. (MZFC-HE 35651);
note the lack of apical pits and pale lower margins of the scales in the first
row of dorsals. (B) Geophis sieboldi (MZFC-HE 27269); note the evident
apical pits and dark lower margins of the scales in the first row of dorsals.
Photo of G. sieboldi by J. Reyes-Velasco. A color version of this figure is
available online.
271
BARRAGA
´N-RES ´
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more ventrals (151–152 in females and 149 in males; 125–
136 and 116–123, 118–124 and 114, and 129–140 and 125–
139 in females and males of G. carinosus,G. juarezi,andG.
turbidus, respectively). Additionally, the new species differs
from all species in the G. omiltemanus group, G. annuliferus,
G. sanniolus,andG. sartorii by having the fifth supralabial
and parietal in contact (anterior temporal separating fifth
supralabial and parietal).
Finally, Geophis berillus sp.nov.differsfromthe
remaining species in the G. sieboldi group as follows: from
G. nasalis and G. sieboldi by the absence of paired apical pits
(paired apical pits present); additionally from G. sieboldi by
having the lower portion of each scale in the first dorsal scale
row pale (lower portion of each scale in the first dorsal scale
row dark); from G. occabus by the absence of a light collar in
juveniles (vs. light collar present in juveniles) and by having
more ventrals (151–152 in females and 149 in males; 133–
139 in females and 130–137 in males); from G. dunni and G.
nasalis by having keeled dorsal scales just above the vent
(keeled dorsals in all body, except for neck); and additionally
from G. nasalis by having more ventrals (151–152 in females
and 149 in males; 118–142 in females and 115–130 in males
of G. nasalis).
Description of holotype.—An adult male; head length ¼
10.48 mm, snout–vent length (SLV) ¼357 mm, tail length ¼
69.67 mm; head slightly distinct from neck; snout rounded
from above, length contained 2.4 times in head length; rostral
slightly broader than high, slightly produced posteriorly
between internasals, portion visible from above 0.4 times as
long as its distance from frontal, 1.5 times as long as
internasals common suture; prefrontals in lateral contact with
postnasal and loreal, their length ca. 0.4 times length of snout:
frontal about as broad as long (breadth/length ¼3.47/3.24);
supraocular about as broad as long, approximately 0.9 times as
long as horizontal diameter of eye, forming about posterior
three-fourths of dorsal margin of orbit, 0.4 times as long as
loreal, in contact with prefrontal, frontal, parietal, and
postocular; parietals 1.3/1.4 times as long as broad, their
length approximately 0.5 times head length, their common
suture 1.1 times as long as frontal; one postocular 1.8/1.7
times has long as broad, slightly smaller than supraocular;
nasal divided; postnasal 1.5 times as long as prenasal;
combined length of prenasal and postnasal ca. 0.5 times
loreal length; loreal 1.5/1.6 times as long as broad, contained
3.9 times in snout length, 2 times as long as horizontal
diameter of eye; eye small, contained 6.5 times in snout
length; supralabials 6/6, first in contact with nasals, second in
narrow contact with postnasal and loreal, third in contact with
loreal and orbit, fourth entering orbit and contacting
postocular, fifth largest, in contact with postocular and
parietal, and sixth in contact with posterior temporal; ventral
margin of third supralabial 2.1 times that of second supra-
labial; ventral margin of fifth supralabial 1.8 times that of
fourth supralabial, 1.2 times that of sixth supralabial; anterior
temporal absent; one posterior temporal, separating sixth
supralabial from parietal; posterior temporals separated
posteriorly from each other by five nuchals. Mental broader
than long, rounded anteriorly, separated from chin shields by
first infralabials; infralabials 7/7, first to fourth in contact with
anterior chin shields, fourth and fifth in contact with posterior
chin shields; anterior chin shields 1.3 times as long as broad,
1.2 times as long as posterior chin shields; posterior chin
shields in narrow contact with each other anteriorly, separated
posteriorly by one midgular scale; four midgular scales.
Dorsal scales in 17–17–17 rows, smooth from the head to
the posterior part of the body, gradually becoming distinctly
keeled above vent, and on anterior half of tail; apical pits
absent; ventrals 149; anal plate single; paired subcaudals 43.
Color in preservative.—Dorsal and lateral surfaces of
head Pratt’s Payne’s gray (293); light collar absent:
background color of mental, chin shields, and midgulars
chamois (84). Anterior two-thirds of body medium blue gray
(193) dorsally, Pratt’s Payne’s gray laterally, and chamois
ventrally. Dorsal and lateral surfaces of posterior third of the
body Pratt’s Payne’s gray (293), with brick red spots above
the vent, chamois ventrally; scales on first dorsal scale row
chamois with dark upper margins at level of midbody, mostly
dark in the posterior portion of the tail.
Color in life.—The following description was based on
photographs of the holotype. The dorsal and lateral surfaces
of the head, body, and tail were medium neutral gray (298)
with iridescent shine throughout the body; ventral color from
mental to the end of the tail was chamois (84; Fig. 3A).
Dentition.—Maxilla extending anteriorly to level of
suture between second and third supralabials; anterior tip
of maxilla pointed, toothless; flange projecting medially at
approximately level of middle of maxilla; posterior third of
maxilla curved ventrally in lateral view, bluntly pointed
posteriorly; maxillary teeth 12, recurved; anterior end of
ectopterygoid single, not expanded.
Hemipenial morphology.—Hemipenis extends to level
of subcaudal 6 (length ¼11.3 mm); slightly bilobed, sulcus
spermaticus centrolineal, bifurcating at the distal end of
capitulum (bifurcation starts approximately at the middle of
hemipenis); the capitulum has calyces and ossicles that
extend up to three quarters the length of the hemipenis, the
intrasulcar region is densely covered with calyces; distal
region with a fold extending across the lateral and asulcate
faces. A ring of 14 enlarged hook-shaped spines around the
hemipenis; on the sulcate face, the ring has 4 spines arranged
2 by 2 on each side of the sulcus spermaticus; on the asulcate
face there are 6 spines in the main ring with an arrangement
of 3 spines on each side of the sulcus spermaticus;
additionally, there are 2 larges spines at the distal region of
the central ring of hook-shaped spines (Fig. 4).
Variation.—This section is based on the examination of
two paratypes and only describes character conditions that
differ from those in the holotype.
FIG. 4.—Hemipenis of Geophis berillus sp. nov. (MZFC-HE 35651). A
color version of this figure is available online.
272 Herpetologica 78(4), 2022
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Scalation.—Supralabials (on one side) 5–6, ¯
x¼5.5 (5 on
MZFZ 4404 and 6 on MZFZ 4405); posterior chin shields in
broad contact with each other in MZFZ 4404 and MZFZ
4405 and separated posteriorly by one midgular scale in the
holotype; ventrals in females 151–152, ¯
x¼151.5, n¼2;
subcaudals in females 33–34, ¯
x¼33.5, n¼2; total segmental
counts in females 184–185, ¯
x¼184.5, n¼2.
Color pattern in preservative.—In both females, dorsal
surface color uniform plumbeous (295); lateral glaucous
(272); first dorsal row pale buff (1) with raw umber (23)
upper margins that occupy all the scales in the posterior
portion of the tail; ventral surface pale buff (1) and light buff
(2).
Distribution and natural history.—Geophis berillus sp.
nov. is distributed in the Valle de Bravo region in the Estado
de M´
exico, which is part of the Trans-Mexican Volcanic Belt.
The new species appears to be allopatric with respect to the
other species of the G. sieboldi group (Fig. 5). The nearest
records of species in the G. sieboldi group to the type locality
of G. berillus sp. nov. are those of G. petersii from Taxco,
Guerrero, and Ciudad de M ´
exico (Downs 1967; Carmona-
Torres and Gonza
´lez-Herna
´ndez 2014), both around 100 km
away from the type locality of G. berillus (straight line).
Elevation in the Valle de Bravo region goes from 1400 m to
2600 m, increasing toward the northeast. The vegetation is
mainly composed of pine–oak forest and induced pastures
(Fig. 6). The climate in the municipality is temperate
subhumid with rains in summer, and annual seasonal
precipitation averages 1024.7 mm. The rainy season spans
from June to September, sometimes extending to October.
The mean temperature of the hottest months is below 228C
(May, June, July, and August), and in the coldest months, the
temperature is between –38C and 188C (November and
December; INAFED 2019). Specimens of Geophis berillus
sp. nov. were collected between 2328- and 2272-m elevation.
The holotype and one paratype were found under rocks, and
the other paratype was found active above the ground. All
specimens were collected in morning hours. The activity of
this species appears to be restricted to the period of spring–
summer with the highest precipitation (between May and
July).
Etymology.—The specific name is treated as a noun in
apposition and comes from the Latin ‘‘ berillus,’’ meaning
beryl. This mineral is colorless in its pure form but can attain
a wide variety of colors in the presence of impurities. The
name references the iridescent shine that is present
FIG. 5.—Distribution of species in the Geophis sieboldi group within Mexico, where a record from Santa Mar´
ıa Pipioltepec is considered as G. berillus sp.
nov. (see Discussion section). State names are indicated. A color version of this figure is available online.
273
BARRAGA
´N-RES ´
ENDIZ ET AL.—NEW SPECIES OF THE GEOPHIS SIEBOLDI GROUP
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throughout the otherwise dark body of all known specimens
of the new species.
DISCUSSION
The G. sieboldi group was recovered as monophyletic but
with low support. The problematic node links G. petersii
with a clade that contains the remaining species in the group.
Downs (1967) remarked that G. petersii is the most
morphologically distinctive member of the G. sieboldi group.
The species has an enlarged rostral scale, large internasals
and postnasals, and short prefrontals and loreals, like
members of the G. dubius group (Downs 1967). However,
osteological and hemipenial traits suggest a close relationship
between G. petersii and other species assigned to the G.
sieboldi group (Downs 1967). Our own mitochondrial tree
suggests that members of the G. championi and G.
latifrontalis group are more closely related to the G. dubius
group than G. petersii, but there is low nodal support for the
relationships between species groups. Additional sampling of
loci and species is necessary to rigorously evaluate the
monophyly of Downs’s (1967) species groups and the
relationships between them.
Geophis berillus sp. nov. shows nearly all the characters in
the definition of the G. sieboldi group proposed by Downs
(1967). The new species differs from the Downs (1967)
definition by the absence of apical pits, as occurs in G.
occabus and G. petersii. However, our morphological and
molecular analyses showed that the assignment of G. berillus
sp. nov. to the G. sieboldi group is correct. The addition of G.
berillus sp. nov. increases the number of species in the group
to 18, of which 8 occur in Mexico.
Geophis berillus sp. nov. is closely related to G. sieboldi
but differs by the absence of apical pits (present in G.
sieboldi) and by the color pattern of the first row of dorsal
scales (Fig. 3). Furthermore, some scale counts of G.
berillus sp. nov. are barely outside the known variation
range in G. sieboldi. The male holotype of G. berillus sp.
nov. has 43 subcaudals and 192 total segmental counts,
whereas males of G. sieboldi have 37–42 subcaudals and
segmental counts for both sexes are between 181 and 191.
Females of G. berillus sp. nov. also have fewer subcaudals
(33) than females of G. sieboldi (34–38). There is a record
of G. sieboldi (MZFC 36) from Santa Maria Pipioltepec at
2250 m of elevation in Valle de Bravo, Estado de Mexico
(Aguilar and Casas 2002), approximately 16 km north from
the records of G. berillus sp. nov. in Temascaltepec and
Valle de Bravo (in straight line). The specimen from Santa
Mar´
ıa Pipioltepec could not be examined, but it likely
represents G. berillus sp. nov. based on its geographic
origin. Reliable records of G. sieboldi are known from
Coalcoma
´n, Michoaca
´n, on the Sierra Madre del Sur, and
approximately 340 km west from Santa Mar´
ıa Pipioltepec
(Downs 1967; Pav ´
on-Va
´zquez et al. 2011); from Tecali-
tla
´n, Jalisco, on the Trans-Mexican Volcanic Belt and
approximately 335 km west from Santa Mar´
ıa Pipioltepec;
and from the municipality of Villa de ´
Alvarez, Colima, in
the Pacific coast and around 375 km west from the Valle
de Bravo region (Ahumada-Carrillo et al. 2014). The
records of G. sieboldi are separated from the records in
the Valle de Bravo region by the Balsas Basin, which acts
as an important climatic and biogeographic barrier for the
flora and fauna of central Mexico (INECC 2020), limiting
gene flow between the populations located in the
biogeographic provinces that surround it (Herna
´ndez-
Leal et al. 2019). However, it is necessary to examine the
specimen from Santa Mar´
ıa Pipioltepec and additional
material from the locality to confidently establish their
taxonomic identity.
The new species described here joins other 101 reptile
species reported from Estado de M´
exico (Lemos-Espinal
and Smith 2020). A member of the G. chalybeus group, G.
bicolor, is the only other species in the genus that is
certainly known to occur in Estado de M ´
exico (Camarillo-
Rangel and Smith 1992). The presence of G. petersii also
seems likely, given that the state represents a large gap in
the distribution of the species between Michoaca
´n,
northwestern Guerrero, and an old dubious record from
Ciudad de M´
exico (Downs 1967; Carmona-Torres and
Gonza
´lez-Herna
´ndez 2014). Lemos-Espinal and Smith
(2020) reported the anguid lizard Barisia herrerae as
endemictoEstadodeM
´
exico, but the species is in fact
also found in the state of Morelos (Zald´
ıvar- River ´
on and
Nieto-Montes de Oca 2002). Thus, G. berillus sp. nov. is
the only known reptile species endemic to Estado de
M´
exico. Although future field work may reveal G. berillus
sp. nov. to be more widespread, its apparently restricted
range is worrying considering that Estado de M´
exico is one
of the Mexican states with the highest human population
FIG. 6.—Habitat of Geophis berillus sp. nov. at the type locality. A color
version of this figure is available online.
274 Herpetologica 78(4), 2022
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density and more severe environmental degradation
(Cha
´vez and Ceballos 1998).
UPDATED KEY TO THE MEXICAN SPECIES OF THE SIEBOLDI GROUP
1a. Dorsal scales in 15 rows ................................................. 2
1b. Dorsal scales in 17 rows ................................................. 5
2a. Pale collar absent............................................................. 3
2b. Pale collar present ................................ Geophis laticollaris
3a. Dorsal scales smooth except above vent; paired apical
pits absent ........................................................................ 4
3a. Dorsal scales keeled except on nuchal region; paired
apical pits present......................................... Geophis sallei
4a. Ventrals 140–158 in males, 145–148 in females;
subcaudals pale ..........................................Geophis petersii
4b. Ventrals 128–130 in males, 130–139 in females;
subcaudals mostly dark ............................Geophis pyburni
5a. Pale collar absent............................................................. 6
5b. Pale collar present .................................... Geophis occabus
6a. Ventrals 143–151 in males, 147–154 in females; dorsal
keeling begins posteriorly to midbody........................... 7
6b. Ventrals 115–130 in males, 118–142 in females; dorsal
keeling begins anteriorly to midbody........Geophis nasalis
7a. Paired apical pits absent; scales on first dorsal row
pale with dark upper margins ..... Geophis berillus sp. nov.
7b. Paired pical pits present; scales on first dorsal row
dark with pale centers.............................. Geophis sieboldi
Acknowledgments.—Support for this work was provided by grants from
Direcci´
on General de Apoyo al Personal Acad ´
emico, Universidad Nacional
Aut´
onoma de M´
exico (PAPIIT grant number IN-216619 and IN-218022)
and Consejo Nacional de Ciencia y Tecnolog´
ıa (CONACyT A1-S-37838) to
UOGV. We thank Pe˜
nitas de Godinez A.C. and Reserva Ecol ´
ogica ‘‘El
Pe ˜
non’’ for logistic support, J. Reyes-Velasco for the photograph of G.
sieboldi, and A.E. Valdenegro-Brito, D. Garc´
ıa-Morales, and D. Rivera for
their help during field work. All specimens were collected under a collecting
permit provided by the Secretar´
ıa de Medio Ambiente y Recursos Naturales
(Permit Number FAUT-0243) to UOGV.
RESUMEN:DescribimosaGeophis berillus sp. nov una
nueva especie del grupo Geophis sieboldi con base en
tres espec´
ımenes de la regi´
on de Valle de Bravo en la
Faja Volca
´nica Transmexicana. La nueva especie se
diferencia de otros miembros del grupo por poseer 17
hileras de escamas dorsales sin fosas apicales, 149 y 152–
153 ventrales (en machos y hembras, respectivamente) y
la porci´
on inferior de cada escama en la primera hilera
de escamas dorsales clara. La nueva especie es
alopa
´trica con respecto a otras especies de Geophis.
Un ana
´lisis filogen ´
etico basado en DNA mitocondrial
(cyt-b) respalda la inclusi´
on de Geophis berillus sp. nov
en el grupo G. sieboldi ysurelaci
´
on como grupo
hermano de G. sieboldi, lo cual se corrobora con la
evidencia morfol´
ogica.
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Accepted on 3 August 2022
Published on 14 December 2022
Associate Editor: Gabriela Parra-Olea
APPENDIX
Specimens Examined
Taxa are presented in alphabetical order. ANMO is an abbreviation for
field numbers of uncatalogued specimens that will be deposited in the
MZFC-HE.
Geophis omiltemanus.—MEXICO: GUERRERO: Municipality of Chilpan-
cingo de Los Bravo, Omiltemi, 17833023 00N, 99841012.98400 W (MZFC-HE
4125).
Geophis occabus.—MEXICO: GUERRERO: Municipality of Atoyac de
´
Alvarez: El Molote, 17825 014.400 N, 100810015.700 W, elevation 1787 m
(MZFC-HE 25530, 22167-22170, 25528, 25529, 25531, 25532, 25552); 1.4
km E of El Molote, 17825010.6 00 N, 100809028.800W, elevation 2,014 m
(MZFC-HE 22160, 22162-22166, 25551).
Geophis laticollaris.—MEXICO: OAXACA: Municipality of Santa Mar´
ıa
Yucuhuiti: Miramar, deviation San Pedro Siniyuhi, 16859055.400 N,
97847053.200W, elevation 1,756 m (ANMO 1973); carretera Miramar-Llano
Grande, 16859046.400N, 97847045.600 W, elevation 1,745 m (ANMO 1974).
Geophis sallei.—MEXICO: OAXACA: Municipality of Santa Catarina
Juquila: carretera R´
ıo Grande-Juquila, 16811028.100N, 97818027.100 W (AN-
MO 2026); Municipio Pluma Hidalgo (MZFC-HE 22615).
Geophis sieboldi.—MEXICO: COLIMA: Municipality of Villa de Alvarez: 7
km N of turn off to El Chivato, on Chiapa-Montitla
´n road, 19823034.9600N,
103840019.22800W, 1,320 m (MZFC-HE 27269).
276 Herpetologica 78(4), 2022
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