A New Species of Pseudocerastes with Elaborate Tail
Ornamentation from Western Iran (Squamata: Viperidae)
Hamid Bostanchi1, Steven C. Anderson2,5,6, Haji Gholi Kami3, and Theodore J. Papenfuss4,5
1P.O.Box 31375-378, Mehrvilla, Karaj, Iran;Email:firstname.lastname@example.org;
2Department of Biological Sciences, University of the Pacific, Stockton, California, USA 95211;
Email:email@example.com;3Department of Biology, Faculty of Sciences, Agriculture Sciences and
Natural Resources, Gorgan University, Gorgan, Golestan Province, Iran;Email:hgkami2000@
yahoo.com;4Museum of Vertebrate Zoology, University of California, Berkeley, California,
A new species of viper, Pseudocerastes urarachnoides, is described from the Zagros
Mountains in western Iran. The new species has a short tail, few pairs of subcaudals
(15 in the known specimens), the distal pairs forming an oval knob-like structure; lat-
eral dorsal caudal scales projected to form elongate “appendages” along the sides of
the terminal knob. Several rows of lateral dorsal scales are weakly keeled and outer
rows are only faintly keeled. We speculate that the caudal appendage may serve as a
lure for prey in an ambush predator.
KEYWORDS: Pseudocerastes urarachnoides, Pseudocerastes persicus, Pseudocerastes fieldi,
new taxon, Iran, caudal lure, caudal ornamentation, Viperidae
The Second Street Expedition to Iran (1968) collected amphibians and reptiles incidental to the
mammals that were the primary objectives. These specimens were deposited in the Field Museum
of Natural History, where one of us (SCA) examined and identified them in 1970. The first impres-
sion of FMNH 170292, seen through the bottle in the preparations room, was that a small solpugid
was clinging to its tail. Subsequent examination revealed that the snake was a specimen of
Pseudocerastes with a peculiar growth at the tail tip. It was identified as P. persicus, with which it
agreed in most particulars. As there was only the single specimen, it was not possible to say whether
the pecular growth of the tip of the tail had a genetic origin or was, perhaps, some sort of tumor or
caused by some parasite. Thus, the specimen languished, but was not forgotten, for nearly four
decades. Then, in 2003, one of us (HB) collected a second specimen with identical tail ornamenta-
tion and similar scale counts and morphology. It seems likely that there has been genetic continu-
ity in this character over the past 35 years. Were the caudal appendage the result of a characteristic
tumor or due to the action of a parasite, we might expect it to have been observed elsewhere and,
perhaps, in other species. We believe that these two specimens represent an undescribed species,
related closely to Pseudocerastes fieldi and P. persicus. This appears to be the most elaborate mor-
phological caudal ornamentation yet reported in a snake, with the possible exception of the rattles
of Crotalus and Sistrurus.
PROCEEDINGS OF THE CALIFORNIAACADEMY OF SCIENCES
Volume 57, No. 14, pp. 443–450, 13 figs., 1 table. September 15, 2006
5Research Associate, California Academy of Sciences.
6Address for correspondence.
Reprinted from the PCAS, ser. 4, vol. 57 (15 September 2006)
Pseudocerastes Boulenger, 1896
TYPE SPECIES: Cerastes persicus Duméril, Bibron, and Duméril, 1854, by monotypy
DEFINITION.— Head distinct from neck, covered with small scales; pupil of eye vertical; nos-
tril directed outwards and upwards, in large undivided nasal shield (pierced between two small
scales, a larger crescentic anterior and a smaller scale-like posterior [Gasperetti 1988:350]) (nasal
aperture in a large circular or crescentic shield, the upper part of the aperture leading into the
supranasal sac [Smith 1943:490, fig. 155A]); supralabials with serrated lower margin and with
inner groove to receive lower lip (The structure of the lips, to provide complete closure of the
mouth, and the valvular prominence within the nasal aperture, are typical desert modifications
against the ingress of blown sand. They are found also in Eristocophis [Smith 1943:490]); body
scales in 21–25 longitudinal rows, none obliquely disposed; keels on body scales do not reach pos-
terior edge of scale but end in swollen knob before outer edge, keels not serrated; ventrals round-
ed, without lateral keels; tail short, subcaudals paired (Leviton et al. 1992:114–115).
DISTRIBUTION.—The North Arabian Desert from Sinai and southern Israel, Jordan, Iraq,
southwestern Iran east to Afghanistan and Pakistan west of the Indus River, outlying population in
northern Oman. (Fig. 13).
We include here brief descriptions of the previously recognized taxa of Pseudocerastes for
comparison with the new species. Some authors have considered P. fieldi a subspecies of P. persi-
cus. There appears to be a geographic hiatus in the distribution of the genus, P. persicus and P. fiel-
di nowhere known to be parapatric, their ranges separated by the Zagros Mountains. For this rea-
son and the differences in venom properties (see below), we prefer to recognize them at the species
Pseudocerastes persicus (Duméril, Bibron, and Duméril, 1854)
Cerastes persicus Duméril, Bibron, and Duméril, 1854:1443, pl. 78b.
DESCRIPTION (From Smith 1943:490–492, fig. 155).—Head depressed, snout short and broad-
ly rounded; diameter of the eye less than its distance from the mouth; nostril very large, pierced in
a large circular or crescentic nasal, bounded above by a supranasal which may be broken up; two
scales between the nasal and the rostral; scales on top of the head small, imbricate, smooth on the
snout, keeled behind in the young, tuberculate and more strongly keeled in the adult; an erect horn-
like scale above the eye surrounded by small scales; 9–12 scales on a line between the horns; 16–20
scales round the eye; 3–4 scales on a line between the eye and the nasal; temporal scales small,
keeled; 13–14 supralabials, 4 series of scales between them and the eye, 1st pair of infralabials larg-
er than the others; a pair of large anterior genials, the scales posterior to them being much smaller.
Scales in 23 or 25:23 or 25: 19 rows, striated and strongly keeled, the outermost scales strong-
ly overlapping the ventral scales. V 144–158; C 34–49, paired.
Hemipenis short, extending to the 8th caudal plate, deeply forked; the distal end is calyculate,
the remainder spinose, the largest spines being at the proximal end; sulcus lips also spinose.
Snout-vent length 688–690 mm, tail 80–85 mm.
Grayish-brown above, with squarish, dark brown, black-edged spots, which alternate with one
another on either side of the vertebral line, or are confluent to form cross-bars; sides of the body
with rounded, less distinct spots; top of the head pale grey, upper lip and side of the head darker,
the two colors meeting in a sharply defined line which extends from the eye to the angle of the
mouth; whitish beneath, spotted with brown. In the adult the markings are much less distinct and
may be almost entirely absent. In large adults, tip of tail often dark. An adult from Kacha,
444 PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES
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Baluchistan, is heavily marked and mottled with black and cream.
Total length: 890 mm; tail 110 mm.
DISTRIBUTION.—Southeastern Anatolia, Turkey and Iran east of the Zagros Mountains
through the Iranian Plateau to central Afghanistan and western Pakistan (Fig. 13). Gasperetti
(1988:353, fig. 127) shows four localities in northern Oman and the Musandam Peninsula.
NOTE.— Wall (1913:64) described Pseudocerastes bicornis from Khajuri Kach, Waziristan,
Pakistan, based on a single specimen now in the Natural History Museum, London. The specimen
consists of the head and anterior one-fourth of the body (Smith 1943:492). Subsequent authors
(Minton 1966; Mertens 1969; Gasperetti 1988) have placed it in the synonymy of P. persicus,
although Khan (2002:190) regards it as distinct. It must be noted that were the two specimens here
described as a new species missing the tails, they would be identified as P. persicus.
Pseudocerastes fieldi Schmidt, 1930
Pseudocerastes fieldi Schmidt, 1930:227, fig. 2 (Type locality: Ayn Bair, Jordan).
DESCRIPTION.—Head depressed, snout is very short and broadly rounded; diameter of the eye
less than its distance from the mouth; nostril very large, pierced in a large circular or crescentic
nasal, bounded above by a supranasal which may be broken up; two scales between the nasal and
the rostral; the upper head scales are small, imbricate, keeled; there is an erect horn-like tubercle
above each eye, covered with several imbricate scales; 9–12 scales on a line between the horns; 15
scales around the eyes; one or two series of scales between the nasal and the rostral; scales on top
of the head small, imbricate, smooth on the snout, keeled behind; scales on top of the head small,
imbricate, smooth on the snout, keeled behind; 13 supralabials, three series of scales between the
eye and the labials; four infralabials in contact with the chin shields (genials). 1st pair of infralabi-
als larger than the others; a pair of large anterior genials, the scales posterior to them being much
smaller. Dorsal scales are strongly keeled in 21–23 rows; ventrals 134–138; the anal is entire, sub-
caudals, 35–38, divided (Schmidt's type had 21 dorsal scale rows, 134 ventrals, 35 subcaudals);
total length 890 mm, tail 110 mm, TL/T = 6.1–8.6.
Colors are grayish or brownish above with four series of large dark spots, the two median rows
sometimes confluent and forming cross bars; a dark streak on each side of the head from the eyes
to behind the gape; the under parts are whitish, dotted with dark and a lateral series of dark spots.
(Schmidt 1930:227–229; Gasperetti 1988:352–354, Table15).
DISTRIBUTION.—Sinai, Israel, Jordan, Syria, Iraq, southwestern Iran (Fig. 13). The specimen
cited by Anderson (1963:472) from Binak, Iran, upon reexamination, is identified here as P. fieldi
NOTE.— Probably the main external morphological difference between P. persicus and P. fiel-
di is that the scale rows of P. persicus are all strongly keeled, whereas in P. fieldi several lateral
rows are nearly smooth and the outer rows are entirely without keels. Pseudocerastes fieldi also has
a significantly shorter tail. Sexual dimorphism has not been studied adequately in either taxon.
Bdolah (1986) demonstrated that the composition and properties of the venoms of P. fieldi and
persicus differ greatly. The venom of P. persicus showed the typical complexities of most viperid
snake venoms with potent hemorrhagic activity whereas that of P. fieldi demonstrated none. The
venom of P. persicus has a yellow pigment typical of most snake venoms and that of P. fieldi is
completely lacking in yellow flavin pigment and its isoelectric focusing profile is a simple one with
very few protein bands. Pseudocerastes persicus, on the other hand, had close to 30 protein bands
spanning a wide pH range. It was concluded that these differences indicate a long genetic separa-
tion of the two forms (Bdolah 1986:726) (Gasperetti 1988:352–353).
BOSTANCHI ET AL.: NEW SPECIES OF PSEUDOCERASTES FROM IRAN 445
The tail tip is often dark in adults of both taxa, suggesting the possibility of caudal luring.
(Gasperetti 1988:354, Table 15).
Pseudocerastes urarachnoides Bostanchi, Anderson, Kami, and Papenfuss, sp. nov.
MATERIAL EXAMINED.—HOLOTYPE: FMNH 170929 [♀], Iran: Ilam Province: 70 km SW Ilam [prob-
ably on road to Amirabad and Mehran], collected by Daniel R. Womochel and Anthony F. DeBlase, Second
Street Expedition to Iran, 27 August 1968 (see map, Fig. 13). PARATYPE: ZMGU [♂], 1300, Iran: Kermanshah
Province: 25 km south of Qasr-e-Shirin on road to Gilan-e Gharb, open level area in agricultural region, ca.
200 meters elevation, collected by Hamid Bostanchi, May 15, 2001 at about 0800 hrs (see map, Fig. 13).
DIAGNOSIS.— A Pseudocerastes with a short tail (TL/T = 9.65), few pairs of subcaudals (15 in
the known specimens), the distal pairs forming an oval knob-like structure; lateral dorsal caudal
scales projected to form elongate "appendages" alongside terminal knob. Several rows of lateral
dorsal scales are weakly keeled.
DESCRIPTION OF HOLOTYPE (FMNH 170929 ♀, [Figs. 1–2, 8, 10]; head scales based on
paratype, ZMGU 1300 ♂[?] [Figs. 5–7, 9]).—The head of the holotype is severely damaged and
accurate counts of many of the head scales are not possible; consequently the description of miss-
446 PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES
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FIGURES 1–4. (1) Holotype, FMNH 170929, dorsal view (SCA photo). (2) Holotype, FMNH 170929, ventral view (SCA
photo). (3) Paratype, ZMGU 1300, dorsal view (James Parham photo). (4) Paratype, ZMGU 1300, ventral view (HGK
ing head characters is based on the paratype. Head depressed, snout
short and broadly rounded; the upper head scales small, imbricate,
keeled; there is an erect horn-like scale above the eye surrounded by
small imbricate scales; 16 scales on a line between the horns; (Fig. 6);
17 scales around the eyes; three series of scales between the eye and
the labials; two series of scales between the nasal and the rostral;
11/12 upper labials; 13/12 lower labials, 3–5 in contact with the chin
shields; anteriormost lower labials enlarged, in contact behind mental
and in contact with one pair of genials (fig. 7). Dorsal scales strongly
keeled, in 21 rows at level of 6th ventral, 23 rows at level of 73rd ven-
tral, 17 rows at level of 145th ventral; several lateral rows are weakly
keeled but the outer row is faintly, but distinctly keeled at midbody
(Fig. 10); ventrals 145; the anal is entire, subcaudals 15 pairs; total
length 531 mm, tail 55 mm, TL/T = 9.65.
Tail short, with only 15 pairs of subcaudals; dorsolateral caudal
scales adjoining subcaudals have elongated keels, progressively
longer from proximal to distal end of tail, keels of distal-most becom-
ing entire scale, the longest measuring 11.2 mm; tail terminates in an
elongate, oval, bulb-like structure, measuring 10.4 mm, apparently
formed of last pair of subcaudals, much enlarged, and a single
enlarged dorsal scale; lateral scales elongated to the extent that they
give the impression of arthropod legs (Figs. 8–9). The caudal verte-
brae extend well into this structure and are not deformed or modified
Colors are grayish and brownish above with four series of large
dark spots, the two median rows sometimes confluent and forming
cross bars; a dark streak on each side of the head from the eyes to
behind the gape; the under parts are cream, with a lateral series of
dark spots (Figs. 1–4).
REMARKS ON PARATYPE.— ZMGU 1300 is a juvenile, apparent-
ly male (see Table 1 for counts and measurements). The caudal orna-
mentation is less well developed (Fig. 9), possibly a factor of age.
The new species most closely resembles Pseudocerastes persicus
in the dorsal scale characters which distinguish that taxon from P. fiel-
di, apart from the greatly shortened tail and the elaborate caudal
appendage, which set it apart from both. To the human observer this
caudal appendage greatly resembles an arthropod clinging to the tail
Unfortunately, neither specimen is in ideal condition, the head of
FMNH 170929 having been severely damaged and ZMGU 1300 hav-
ing partially rotted prior to proper preservation.
BOSTANCHI ET AL.: NEW SPECIES OF PSEUDOCERASTES FROM IRAN 447
FIGURES 5–10. (5) Lateral view of head of Paratype, ZMGU 1300 (James Parham
photo). (6) Dorsal view of head of paratype, ZMGU 1300 (HGK photo). (7) Ventral view
of head of paratype, ZMGU 1300 (James Parham photo). (8) Tail ornamentation of
Holotype, FMNH 170929 (SCA photo). (9) Tail ornamentation of paratype, ZMGU 1300
(HGK photo). (10) Ventrolateral scale rows keeled (holotype, FMNH 170929) (SCA
DERIVATION OF NAME.— From the Greek: ura = tail;
arachno = spider; ides = similar to.
DISCUSSION AND SPECULATION.—This unusual snake
occupies a region that lies between the recorded ranges of P.
persicus and P. fieldii. Its discovery raises a number of inter-
esting questions and speculations. Only one of us (HB) has
seen this species alive, and while we speculate that the caudal
appendage functions as a caudal lure, this remains to be veri-
fied. While anthropomorphic interpretation should be avoided
where documentation is lacking, caudal luring is known for
several species of snakes, e.g., Bitis caudalis, Crotalus
cerastes, Sistrurus catenatus, Agkistrodon contortrix,
Acanthophis antarcticus, Acanthophis praelongus, Morelia
viridis, and others, and will probably be verified in many
species with differentially colored tails. Gasperetti (1988:354)
suggested that this might be the case for the previously known
species of Pseudocerastes. Neill (1980) reviewed the litera-
ture on caudal luring in juvenile snakes, especially crotalids
and boids, and suggested that the loss of contrasting tail color
with age marked the transition from ectothermic prey (e.g.,
amphibians, lizards, scorpions, centipedes) to mammals.
Greene (1992:111–112) added additional species to the list of
snakes exhibiting caudal luring and suggested that contrasting
tail coloring and luring behavior might be a synapomorphy in the Crotalinae, Viperidae, or larger
clade. This raises the question of the elaborate and sophisticated appearance of the caudal
appendage in our new species, as the waving or wriggling motion of a distinctively colored tail tip
seems perfectly adequate to attract lizard and anuran prey. We can only speculate that in the case of
the present species, the caudal lure serves to deceive a more specific kind of prey, such as shrews
or birds. Indeed, ZMGU 1300 contains an undigested, unidentified passerine bird in the stomach
(the feet protruding through the body wall). When sufficient specimens become available, addition-
al stomach contents should be examined and observations made of the behavior of captive individ-
448 PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES
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FIGURES 11–12. Radiographs of holo-
type showing undeformed caudal vertebrae
extending into bulbus area of tail indicating
that the tail tip was neither damaged nor
regenerated. (Radiographs by Mark Zim-
FIGURE 13. Map showing distribution of the genus Pseudocerastes (lim-
its of distribution uncertain). (Map prepared by Karen Klitz.)
uals. Latifi (1991:131) states that the diet of P. persicus consists of lizards and mice; Khan (2002)
gives deserticolous lizards and arthropods as prey items.
As both available specimens were initially preserved in formalin, no tissue samples suitable for
molecular analysis are available. Should such become available in the future, by comparing DNA
from the three known species of Pseudocerastes, it may be possible to obtain a molecular clock esti-
mate of the time required to evolve such a structure.
The venom of Pseudocerastes persicus and P. fieldi differ in their chemical composition and in
their physiological action (Bdolah 1986:726), and it will be interesting to compare these with the
venom properties of the new species, if and when the opportunity arises.
We thank Professor Martha Bowsky, University of the Pacific, who assisted with the etymolo-
gy of the species name; Karen Klitz, Museum of Vertebrate Zoology, University of California,
Berkeley, who prepared the map (Fig. 13); James Parham, University of California Museum of
Paleontology, who took photos of the paratype; Professor Richard Tenaza, University of the Pacific,
who helped in preparing two of the illustrations; and Mark Zimmerman, DVM, who took the radi-
ANDERSON, STEVEN C. 1963. Amphibians and reptiles from Iran. Proceedings of the California Academy of
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BDOLAH, AVNER. 1986. Comparison of venoms from two subspecies of the false horned viper (Pseudocerastes
persicus). Toxicon 24(7):726–729, figs. 1–2.
BOULENGER, GEORGE A. 1896. Catalogue of the Snakes in the British Museum (Natural History). Volume III.,
BOSTANCHI ET AL.: NEW SPECIES OF PSEUDOCERASTES FROM IRAN 449
TABLE 1. Counts and measurements for specimens examined.7
P. urarachnoides P. persicus P. fieldi
FMNH ZMGU Latifi Latifi CAS CAS
170929 1300 (2000) (2000) 86633 159051
Sex ♀♂[?] ♀♀
Ventrals 145 146 144–163 142 153 158
Subcaudals (pairs) 15 15 38–50 46 41 38
Anal plate single single single single single single
Dorsal scales at midbody 21 23 23–25 21 23 23
Scales around eye –818/17 15–20 16 20 18
Interorbital scales ~9–10 16 10–15 10 15 12
Scales between eyes and
upper labials 3 3 2–4 3 4 4
Upper labials ~8 11/12 11–14 – 14/13 11/13
Lower labials 13/12 15/14 13–17 – 18/17 13/13
Snout-vent (mm) 531 386 1160 750 515 279
Tail (mm) 55 46 130 80 75 39
7Additional counts and measurements for P. persicus and P. fieldi are given by Gasperetti (1988:354, table
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