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UNIVERSITY OF ILLINOIS
URBANA

ZOOLOGICAL SERIES

OF
FIELD MUSEUM OF NATURAL HISTORY

Volume 29 CHICAGO, NOVEMBER 26, 1943 No. 2

NOTES ON CORAL SNAKES FROM MEXICO

BY KARL P. SCHMIDT

CHIEF CURATOR, DEPARTMENT OF ZOOLOGY
AND

HOBART M. SMITH
DEPARTMENT OF ZOOLOGY, UNIVERSITY OF ROCHESTER

On the occasion of a visit of the junior author to Field Museum
we had the opportunity to review together and to discuss the geo-
graphic relations of certain of the coral snakes of the genus Micrurus,
which have long formed a special interest of the senior author. We
find it desirable to extend the geographic partition of Micrurus
nigrocinctus, a subspecies complex that enters Mexico only in
Chiapas, and to describe two additional distinct forms from Guerrero,
to one of which we attach the name of the veteran collector W. W.
Brown, and to the other that of Edward H. Taylor. Micrurus dia-
stema diastema, as defined in an earlier publication, is restricted to
Colima and Jalisco, with the re-establishment of Elaps michoa-
canensis as a subspecies of diastema. Micrurus nuchalis, formerly
the only coral snake with supra-anal tubercles known from Mexico,
remains relatively distinct from M . n. zunilensis, M. n. ovandoensis,
and M. browni. No specimens of nuchalis other than the six recorded
by the senior author in 1933 have appeared. A single specimen of
coral snake collected at Acapulco, Guerrero, by Dr. Edward H.
Taylor, appears to be related to nuchalis rather than to any other of
the species or races above mentioned. Except for the description of
Micrurus fitzingeri microgalbineus by the junior author and Bryce
C. Brown, these changes are the more significant alterations in the
senior author's arrangement of the Mexican forms of the genus
Micrurus. Numerous further records and modifications of geo-
graphic ranges will be found in the junior author's forthcoming
check list of Mexican snakes.

No. 541 25

THE LIBRARY i*

26 FIELD MUSEUM OF NATURAL HISTORY— ZOOLOGY, VOL. 29"

We are indebted to the United States National Museum, the
Museum of Comparative Zoology, the Museum of Zoology of the
University of Michigan, and Dr. Edward H. Taylor of the Univer-
sity of Kansas for the loan of Mexican coral snakes.

M icrurus nigrocinctus zunilensis Schmidt

Micrurus nigrocinctus zunilensis Schmidt, Proc. Calif. Acad. Sci., (4), 20, pp.
265-267, 1932— Finca El Cipres, lower slopes of Volcan Zunil, Suchitepe-
quez, Guatemala.

This distinct race is known from sixteen specimens: thirteen in
the type series (topotypes) ; one reported by Schmidt (1936, p. 207)
from Olas de Moca, Solola, and another from El Porvenir, San Mar-
cos, Guatemala; and a final specimen here recorded, Mus. Zool.
Univ. Mich. No. 87705, from Mount Ovando, 6,000 feet, Chiapas.
The latter specimen extends the range into Mexico. It is typical,
with 224 ventrals (female, tail incomplete), black rings on body and
tail 20 + 5, and the yellow rings very narrow, practically obsolete
ventrally.

This race appears to be an upland form, occurring at altitudes
from 2,000 to 6,000 feet, and to have much the same range as lati-
fasciatus, which was described from the same type locality.

At lower elevations in Chiapas, from 400 to 1,200 feet, the junior
author has taken two specimens that appear to be closely related to
n. zunilensis, but are distinct in certain characters. No other race
or close relative of nigrocinctus is known from low elevations on the
Pacific slope north of Nicaragua, except nuchalis; the latter as well
as all races of nigrocinctus except zunilensis have the dorsal scales on
the red zones black- tipped, and in this respect differ from the two
Chiapas specimens. Accordingly we conclude that the specimens in
question represent a distinct race that probably extends at low eleva-
tions southward to Honduras and northward perhaps to the Isthmus
of Tehuantepec. It is described below.

Micrurus nigrocinctus ovandoensis subsp. nov.

Type from Salto de Agua, Mount Ovando, about fifteen miles
northeast of Escuintla, Chiapas. Altitude 1,200 feet. No. 111331
United States National Museum. Subadult male. Collected May
19, 1940, by Hobart M. Smith.

Diagnosis. — A coral snake with the general coloration and habitus
of Micrurus nigrocinctus; males with supra-anal tubercles; black
rings single, complete, covering three or four scale rows mid-dorsally,

A/ A T . H i SI . U I 15 .
1943 MEXICAN CORAL SNAKES— SCHMIDT AND SMITH , 27

numbering twelve on body and three or four on tail, in the speci-
mens known ; red rings very broad, the dorsal scales within them not
black- tipped ; yellow rings complete, one and a half to two scale rows
wide; prefrontals in contact with or narrowly separated from supra-
labials. Ventrals 204 (male), 211 (female).

Description of type. — Head scales normal; upper and lower labials
7-7; preoculars 1-1; postoculars 2-2; temporals 1-1-2; pref rental
narrowly in contact with second and third supralabials on one side
(separating nasal and preocular), narrowly separated from them on
the other; ventrals 204; anal divided; caudals 48, all divided; dorsal
scale rows 15, smooth, not pitted; supra-anal tubercles present.

Snout black, the color reaching posterior margin of eye and
posterior part of frontal; mental and three anterior lower labials on
each side black; a broad, yellow parietal ring, involving all except
the posterior tip of the frontal; dorsal and upper lateral surfaces of
the head in the light areas stippled, remainder immaculate; nuchal
black ring involving tips of parietals and six scale lengths on the
body medially as the first of a series of twelve equidistant complete
black rings; all rings except the first and last extending over three
or four scale lengths on the mid-dorsal line, the last involving five;
four black rings on tail, twice as wide as yellow interspaces; black
rings on body bordered by complete yellow rings one and a half to
two scale lengths wide; red spaces very broad, the dorsal scales
within them not black- tipped.

Measurements. — Total length 629; tail 93.

Notes on paratype. — A single paratype, U.S.N.M. No. 111332, is
from the vicinity of La Esperanza, 400 feet, ten miles northeast of
Escuintla, Chiapas, collected May 25, 1940. It is a young female
with 211 ventrals and 32 subcaudals, black rings on body and tail
12+3; the prefrontals touch the third labial on both sides; total
length 207, tail 19. On one side the first and second supralabials
are abnormally fused. Other characters are as in the type.

Comparisons. — From n. zunilensis the present race differs in hav-
ing broad yellow rings, covering one and a half to two scale lengths
and not tending to disappear ventrally (less than one scale row wide
in n. zunilensis, and practically obsolete ventrally), fewer black rings
on body (twelve as against fourteen to twenty), fewer tail rings (four
in male, three in female as against five to seven in male and four to
five in female n. zunilensis), and in having the prefrontals in contact
with or narrowly separated from the labials. The prefrontals are
broadly separated from the labials in most coral snakes and in

28 FIELD MUSEUM OF NATURAL HISTORY— ZOOLOGY, VOL. 29

n. zunilensis. The subcaudals of the single female paratype are fewer
by one than the lowest count known in this sex for n. zunilensis. The
new form differs from Micrurus nuchalis in its larger number of
black rings.

Remarks. — The type was found in a rather unusual habitat. It
was seen at night, crawling rapidly in the limbs of bushes about ten
feet above the ground in the bottom of a nearly dry wash that led
into a larger running stream not far away. The snake was so active
that it had to be shot to prevent its escape. Not impossibly it may
have been searching for small, newly transformed frogs that were
clinging in some numbers to the foliage, but nothing was found in
the stomach.

Micrurus diastema diastema Dume'ril and Bibron

This subspecies is restricted to the states of Colima and Jalisco
by the re-establishment of michoacanensis and the transfer of Guerr-
ero specimens to the new species browni. The range of variation in
ventrals thus becomes 191 to 210 in males, and 207 to 220 in females,
with caudals respectively 45 to 57 and 34 to 45.

Micrurus diastema distans Kennicott

A specimen from Magdalena, Jalisco (U.S.N.M. No. 67374), with
ventrals 237, agrees best in this character with distans. There is no
trace of yellow rings in the somewhat faded specimen. It has a much
higher number of black rings than has hitherto been known in this
form.

Micrurus diastema michoacanensis Duges

Elaps diastema var. michoacanensis Duges, La Naturaleza, (2), 1, p. 402,

pi. 27, 1891.
Elaps michoacanensis Duges, Bull. Mus. Hist. Nat. Paris, 2, p. 60, 1896

Rev. Cien. Bibl. (Soc. Ant. Alzate), 1900-1901, p. 58 (1901).

The type of this form is no longer present in the Duges Museum.
In his revision of the original description, Duges recorded a second
specimen as from Tecpan de Galeana, Guerrero. This coastal locality
may well represent an extension of the range of michoacanensis, and
we are assured that the second specimen corresponds exactly to th
type. This specimen, a female, may be described in some detail.

Description of Tecpan specimen. — Head somewhat flattened, bod;
cylindrical. The scale characters are those of the species, ventral
226, caudals 38, of which the third is undivided.

1943 MEXICAN CORAL SNAKES— SCHMIDT AND SMITH 29

The specimen has faded so badly that it is impossible to dis-
tinguish between yellow and red, both colors faded to creamy white.
Anterior part of head dark brown extending posteriorly to a point
slightly beyond angle of frontal, the posterior edge of the dark area
slightly concave; the edge of this dark snout marking passes
through the postero-lateral part of the first temporal, the upper edge
of the fifth supralabial, and then becomes irregular, passing through
the middle of the lower part of the anterior labials; snout proper,
including internasals, rostral and first supralabial, somewhat
mottled.

Nuchal black ring covers seven scale rows dorsally, and on the
ventral surface covers parts of three whole scutes, its anterior edge
separated from last labial by one scale. Seven black rings on the
body (including nuchal ring but not the band on head), and three on
the tail (the last very small, visible only dorsally where it covers
three dorsal scales and the terminal spine). Black rings four and
one-half to six scale rows long on the back and covering from three
and one-half to five ventrals. Caudal black rings much longer, the
two complete rings separated from each other on the under side by
six scales.

Measurements. — Length of head 16.5; total length 865; tail 88.

Two coral snakes from Apatzingan collected by F. A. Shannon
on the fourth Hoogstraal Expedition to Mexico in 1941 and one
collected near the same place by Hobart M. Smith in 1939 are in
excellent agreement with Duges' description and thus afford the
reasonable assumption that the species is characteristic of the arid
lower part of the basin of the Balsas River. The single female from
Apatzingan agrees closely with the Tecpan specimen; it has 226
ventrals and 40 caudals, and the black rings are 8 + 2. The two
male specimens have ventrals respectively 211 and 214, caudals 50
and 49, and black rings 7+3 and 6+3. All these specimens have
an obscure mottling of brown on the dark tip of the snout and
apparently lack the yellow rings entirely. The scales of the red
zones are entirely without black spots.

Micrurus browni sp. nov.

Type from Chilpancingo, Guerrero. No. 38494 Field Museum
of Natural History. Adult male. Collected by W. W. Brown.

Diagnosis. — A coral snake of the genus Micrurus, with the general
coloration and habitus of Micrurus nigrocinctus, with black-spotted
red scales, and with distinct supra-anal tubercles in adult males.

30 FIELD MUSEUM OF NATURAL HISTORY— ZOOLOGY, VOL. 29

Ventrals 207-220 in males, 226-230 in females; black rings 11 + 4
to 24 + 7, usually more than 17 + 4. Differing from Micrurus
nigrocinctus ovandoensis and from M . nuchalis in having more numer-
ous black rings on body and tail, and a higher number of ventrals.

Description of type. — Body cylindrical, head somewhat flattened ;
head scales normal ; labials 7-7 above and below; preoculars 1-1 ; post-
oculars 2-2; temporals 1-1 on each side; ventrals 220; anal divided;
caudals 50; dorsal scales in 15 rows; supra-anal tubercles present.

Snout black, the black reaching the anterior ends of the parietal
and involving all of the postoculars, the first four upper and the
first three lower labials. Tip of frontal light; nuchal black ring on
tips of parietals, extending five scale lengths on the nape, and cover-
ing the last upper labial, the two last lower labials, and the first
five ventrals, with a pointed forward extension reaching the first
chin-shields; black rings covering three or four ventrals, 19 + 7 on
the body and tail; yellow rings distinct, about one and a half scale
lengths wide, somewhat narrowed below; red rings shortened poster-
iorly; no black spotting on the scales or ventrals of the red rings;
no red rings on tail.

Measurements. — Total length 689; tail 97.

Notes on paratypes. — Nine additional specimens from Chil-
pancingo and one from Omilteme are referred to browni; these are
U.M.M.Z. Nos. 85681-85684; M.C.Z. Nos. 33666-33668; F.M.N.H.
38493, 38495; and B.M. 1895-2-20-9. Occasional specimens have
temporals 1-2 and three specimens have one or two entire caudals.
The range of ventrals in six males is 210-220, and 226-230 in five
females; caudals in males 47-53, and 38-44 in females. The para-
types exhibit various degrees of black spotting of the scales of the
red zones.

Remarks. — The complete absence of supra-anal tubercles in the
specimen U.M.M.Z. 85681, which measures only 10 mm. less than
the type, is explainable only as an individual anomaly; but this
structure is known to fail to develop in occasional specimens of species
in which it normally occurs, when sufficient series are examined. The
present series of coral snakes is variable in another character that
has elsewhere been used as a criterion of subspecific difference;
namely, presence or absence of black spotting of the dorsal scales.

Micrurus nuchalis taylori subsp. nov.

Type from Acapulco, Guerrero. No. 5085 Taylor-Smith Collec-
tion. Adult male. Collected July 29, 1936, by Edward H. Taylor.

1943 MEXICAN CORAL SNAKES— SCHMIDT AND SMITH 31

Diagnosis. — A coral snake related in several respects to Micrurus
nuchalis, but with a larger number of black rings and a larger number
of ventrals. Black rings with very obscure yellow borders, narrowed
on the sides; scales in the red zones black-spotted; snout not mottled
with brown; supra-anal tubercles strongly developed.

Description of type. — An elongate coral snake with cylindrical
body, long tail, and somewhat flattened head. Head scales normal;
upper and lower labials 7-7; preoculars 1-1; postoculars 2-2; tem-
porals 1-1 on each side; ventrals 218; anal divided; caudals 55;
dorsal scale rows 15; supra-anal tubercles well developed.

Snout black, without brown mottling, the black reaching the
anterior borders of the parietals, involving all of the upper postocular
and the anterior border of the lower, cutting across the upper part
of the fourth labial to the labial border; mental light (with brown
marking), anterior half of first lower labial and all of second black.
Tip of frontal light; nuchal black band cutting across tip of parietals,
extreme rear of seventh upper labials, and all of seventh lower labials
to second ventral, six scales long dorsally and covering four ventrals.
Black rings covering two or two and a fraction ventrals, narrowed on
the sides, two and a half scale rows long above; yellow rings barely
indicated by somewhat lightened borders of the black rings; three
black rings interrupted on the sides, i.e., divided into a dorsal and a
ventral spot; tail with three black rings and a black tip, the rings
about twice as long as the yellow interspaces; black rings (including
nuchal) 11 + 4; each dorsal scale in the red zones with a small black
spot at the tip; no black spotting on red ventrals.

Remarks. — This Guerreran coastal form may be regarded as
related to M. nuchalis nuchalis of Oaxaca, from which it is distin-
guished by a higher number of ventrals and of black rings, and a
shorter nuchal ring. It will require additional specimens to define
the possible relations with diastema michoacanensis to the north and
with browni in the highlands of Guerrero.

REFERENCES

BROWN, B. C. and SMITH, H. M.

1942. A New Subspecies of Mexican Coral Snake. Proc. Biol. Soc. Wash.,
55, pp. 63-66.

SCHMIDT, K. P.

1933. Preliminary Account of the Coral Snakes of Central America and Mexico.

Field Mus. Nat. Hist., Zool. Ser., 20, pp. 29-40.
1936. Notes on Central American and Mexican Coral Snakes. Ibid., pp.

205-216,' figs. 24-27.