I

Asiatic Herpetological Research

February 199T

Vol.4, pp. 42-54

1

A New Species of Grass Snake, Natrix(Ophidia:

megalocephala, from the Caucasus
Colubridae) f

NIKOLAI L. ORLOV AND BORIS S. TUNIYEV 2
1^Zoological Institute, Russian Academy of Sciences, St. Petersburg, Russia
2
Causasian State Biosphere Reserve, Sochi, Russia

Abstract. -A new species of Grass Snake, Natrix megalocephala, is described from the Caucasus
Mountains, of Azerbaijan, Georgia, and Russia. It differs from Natrix natrix in having a very thickmassive body, a large broad head, and enlarged frontal and temporal scales. Natrix megalocephala is foundin habitats with Colchida refugia vegetation.
Reptilia, Serpentes, Colubridae, Natrix, Azerbaijan, Caucasus, Georgia, Russia,

Key words:

USSR,

biogeography, distribution, taxonomy.

museum specimens of theand working withNatrixLaurenti
genus
Colchida snakes in the wild, we came to theconclusion that three species of grasssnakes inhabit the Caucasus. This is based
In studying

on a morphological analysis of specimens
in collections. The possible genesis of thespecies and the formation of their presentday habitats is discussed.

Methods

We examined 15 specimens of Natrix
natrix persa Pallas, 15 specimens of N.
natrix scutata Pallas, and 19 specimens of
Natrix from the western Caucasus whichwere thought to be a new species. The
following characters were used: 1- snout

vent length inmm (L); 2-

taillength in mm.

number of scales around the
middle of the body (Sq.); 4- number ofventrals (Ventr.); 5- number of subcaudals(S. cd.); 6- number of upper labials (Lab.);
7- number of lower labials (Sublab.); 8(L. cd.); 3-

length and width of the frontal; 9- length
and width of the parietals; 10- length,
height, and width of the head.

A comparative description of skulls in+This publication combines material previously

publishedinnew species was
For a number of characters we
calculated mean numbers (x), error of mean

Natrixdone.

Introduction

Russian by Orlov and Tuniyev(1986a) with additional information.

© 1992 by Asiatic Herpetological Researchn. scutata and the(m), and standard deviation (a) using
statistics from Lakin (1968).

Results

An analysis of the data show that thegrass snake which occurs within thewestern Caucasus (known as the Colchida)refugia

may be regarded as a separate

species.

This species, due to a very big

head, was given the name Natrix
megalocephala (Orlov and Tuniyev,
1986a). The common English name is the
Colchida Grass Snake.

Nomenclature Remarks

A number of synonyms were proposed
for the Caucasus Grass Snake.

However,

after a detailed study, we came to theconclusion that none of the proposedsynonyms fits the form described.

Nordmann (1840) mentioned two forms
for the Caucasus: Tropidonotus natrix var.
colchica and Tropidonotus natrix var.

nigra. The description and the drawing of
the first form agrees with Natrix natrix
persa (Pallas). That of the second form

agrees with Natrix natrix scutata (Pallas).
Derjugin (1899) regarded the form
Tropidonotus natrix var. nigra as a color
variation of T. natrix. Radde (1899) alsoFebruary 1992

FIG.

1 .

Asiatic Herpetological Research

Various views of the head of the holotype(ZIN 11846) of Natrix megalocephala from
Pitsunda, Abkhazia, Georgia.

FIG. 3.

Vol. 4, p. 43

Ventral view of the holotype (ZIN

11846) of Natrix megalocephala from Pitsunda,
Abkhazia, Georgia.

'

FIG. 2. The head of the holotype (ZIN 1 1846) of
Natrix megalocephala from Pitsunda, Abkhazia,

FIG. 4. Dorsal view of the holotype (ZIN 1 1846)
of Natrix megalocephala from Pitsunda, Abkhazia,

Georgia.

Georgia.

Asiatic Herpetological ResearchVol. 4, p. 44

mentioned that the form. T. natrix var.
scutata Pallas, which had black coloration,
occured in Likani in the vicinity ofDinnik (1902) observed
Borjomi.
Tropidonotus natrix var. ater Eichwald,
which actually are melanistic specimens of
N. natrix. Nikolsky (1913, 1916) gives
three forms of Tropidonotus natrix withregard to the Caucasus: a typical form,

Tropidonotus natrix natrix; T.

n.

var.

Eichwald.
melanistic
toThe latter corresponded
specimens of Natrix natrix.

scutatus Pallas; T. n. var. ater

The synonym "ater" cannot be used as
the

name

for thenew species because

Eichwald (1831) employed it with regard tomelanistic individuals of the valid species
N. n. scutata (Pallas) from the suburbs ofandAstrakhan, Russia.
Terentyev
Chernov (1949) and Milyanovsky (1957)
suggested that N. n. persa and N. n. natrix

Theoccured in the Caucasus.
haveoverwhelming majority of authors
named two forms for the Caucasus: Natrix
n. scutata (Pallas) and N. n. persa (Pallas),Bischoff and Engelmann,
Mertens and Wermuth, 1960).
(see,

1976;

The three forms, N. n. natrix, N. n.
persa and N. n. scutata which inhabit the

USSR territory are given in the field guideof the herpetofauna of the USSR regarding
the Caucasus (Bannikov et al., 1977).

To date there is no definite conception
about the distribution and interaction of
Natrix natrix subspecies, particularly in thewestern portion of its range. Presently
from 3 to 9 subspecies are recognized(Thorpe, 1975). In his recent work Thorpe(1980) suggested two initial centers of
Natrix speciation for the mainland: western

European and eastern European centers.
Natrix megalocephala
Orlov and Tuniyev, 1986

Holotype.

—ZIN 1846, an
1February 1992

mm, tail length 240 mm. Head is coveredby large regular scales. Upper labials 8 on
the right and 7 on the left. Lower labials
are 1 1 on the right and 9 on the left. One
preocular and 3 postoculars on both sides.

The nasal touches 2 upper labials. Parietals
are large, 17 mm in length and 6 mm inwidth. Large anterior chin shields are set in
two rows. Between posterior chin shields
are 3 rows of small scales 1+1+2. Tworows of greatly enlarged irregular scales
follow temporals and parietals. The widthof the anterior chin shields are greater than
The width of internasals
there height.

The length oflength.
their width.
thangreater
prefrontals
Nineteen scales surround the mid-body.
On the level of the 6th ventral scale fromthe head and the 6th ventral from the tailthere are 19 and 17 scale rows respectively.
There are 172 ventrals. Two rows of
subcaudals, 68 scales each. The anal plate
The first row of lateral scales
is divided.
theventrals has a smoothbordering
surface. The scales of the second row arebarely keeled. The remainder are distinctly
keeled. Lateral and dorsal coloration isbright black. The first half of ventrum isspotted with alternating black and whitespots. Towards the tail white coloration
vanishes. White spots become smaller.
equalstheirisSubcaudals are black. Unspotted head isblack from above and white from below.
White coloration extends onto the lower
portion of upper labials. Black stripes goalong the edge of lower labials.

—

ZIN 9039,
Description of paratypes.
18794, 21535, 11243, 18794, 11247,
11862, 9594, 18211, 16653, 5273 (Fig. 5
and Table 1).

—

This snake differs from the
Diagnosis.
various subspecies of the closely related
species Natrix natrix Laurenti in having 1) avery thick massive body; 2) a remarkable
big broad head; 3) enlarged frontal andtemporal scales.

adult female

from Pitsunda, Abkhazia, Georgia, western

Unlike the subspecies of N. natrix, in N.

Caucasus. The specimen was collected in1909 by K. Satunin (Figs. 1, 2, 3 and 4).

megalocephala sutures between closely

Description of holotypes.

— SVL 960

adjacent head shields are not that welldefined. In N. natrix scales which cover
the head from above (prefrontal, frontal,

February 1992

Asiatic Herpetological Research

TABLE 1. Morphological characters of Natrix megalocephala.
N

Vol. 4, p. 45

Vol. 4, p. 46

Asiatic Herpetological Research

FIG.

6.

February 1992

Juvenile

specimenof

Natrixmegalocephala (ZIN 19967).

Biotopic and Elevational Distribution.
Inwestern

Transcaucasia—

Natrixmegalocephala ranges from the Black Sea
slope of the Great Caucasus Ridge up to thesubalpine belt. On the northern slope and
FIG. 5.

Various views of the head of Natrix

in the eastern refugia this species occurs inm (Table 2). The

megalocephala from Lagodekhi, Georgia.

the mountains up to 1000

Great Caucasus Ridge and then streatches

represented by forests of the Colchida type:

along thefoothills up to the area where the
Urushten and Malaya Laba rivers merge insecondary trees, Fag us
orientalis, Quercus iberica, Taxus baccata,
Buxus colchica, Laurocerasus officinalis,
Fagetum nudum, Castanetum colchicum,
Alnetum strutiopteridosum, Fageto-Abieta
More seldom
athirio-mixtogerbosa.

biotypes

Krasnodarsky Territory, Russia.
Isolated populations are found along thesouthern slope of the western Caucasus inandIsolatedof N.

megalocephalaareevergreen

the vacinity of Lagodekhi, Georgia

Quercetum azaleosum.

Vartashen,occurs in transformed areas such as forest

Azerbaijan.
populations are also found on the eastern
slope of Adjaro-Imeretinsky Ridge, in thevicinity of Borjomi, Georgia (Fig. 8).

The species habitat is associated with the
Colchida or western Transcaucasianbotanico-geographicalprovince(Kuznetsov, 1891, 1909). Distributions ofof Natrix
isolated
populations
megalocephala coincide with vegetation
refugia of the Colchida type in BeloLabinsky district, in the canyon of midflow of the Kura River and a number ofrefugia on the southern slopes of theEastern Caucasus.

This snake alsoedge meadows, tea plantations, andNatrixsecondary hornbeam woods.
megalocephala is a mesophyllic species, but
unlike Natrix natrix and Natrix tesselata, it
well adapted to swift montane rivers. In
case of danger, this species can hide inisswift waters.

—

Abundance. It is a common but not
numerous species. It never forms suchdense populations as are found in N. natrix
and N. tesselata. The highest density isobserved

inmixed Alder and Willow

forests along river beds, where up to three

specimens per kilometer walked may beFebruary 1992

Asiatic Herpetological ResearchVol. 4, p. 47

FIG. 7. Skulls oi Natrix natrix scutaia (a, b) and Natrix megalocephala (c, d).

elevations of 600 to 1600

encountered.

—

On theSeasonal and Daily Activity.
near
Sea
of
the
Caucasus
Black
coast
of
comes
out
Sochi, N. megalocephala
in
March
and
remains
activehibernationAt
until November or early December.

m the activity

For instance, in a gorge
periodof the Achipse River, we have observed
active snakes from the end of April to theend of September. In the spring and fall N.
isshorter.

megalocepliala is active in the afternoon. In
these seasons snakes may be encounteredAsiatic Herpetological ResearchVol. 4, p. 48

February 1992

1- mouth of theDistribution of Natrix megalocephala.
Russia, Krasnodarsky Territory:
Urushten River; 2- Kisha Cordon, Caucasian Reserve; 3- Stanitsa (a small settlememt in the country side)of Khamyshki; 4- Tuapse; 5- Lazorevskoye; 6- Sergei-Pole; 7- Sochi; 8- Malaya Khosta River; 9- Yew-box
Grove; 10- Achipse River. Georgia: 11- Lake Ritza; 12- Sukhumi; 13- Batumi; 14- setdement of Kheba;
15- setdement of Likani; 16- Borjomi; 17- Lagodekhi. Azerbaijan: 18- setdement of Vartashen. T- Type
locality, Pitsunda, Abkhazia, Georgia, a- Isotherm of the coldest month, above -3°C. b- Amount of

FIG. 8.

precipitation not less than 800

mm (after Gerasimov, 1966).

basking up to 1000 m away from a water
source during the warmest hours. In thesummer along the Black Sea coast N.
megalocephala is active in the morning,
during the late afternoon, and at night. For
instance, in the Yew-box Grove of the
Caucasus Preserve in the Labirintovayacollected in the canyon of the Achipse River

Wash, Sochi, Krasnodarsky Territory,
Russia, we observed N. megalocephalacompared to the other representatives of thegenus. A female, which was collected in
the Yew-box Grove of the Caucasus
Preserve in the Labirintovaya Wash, Sochi,
Krasnodarsky Territory, Russia duringhunting for Pelodytes caucasicus in Julyfrom 2100 until 2330 hours. Summer
activity at mid-elevations has a daily two

peaked pattern: from 0900 until 1130
hours, and from 1630 until 1800 hours. It
interesting to note that in the summer N.
natrix and N. tesselata are active strictly
during the day along the Black Sea coast ofisthe Caucasus.

Breeding.

—A female N. megalocephala,on 11 August 1985, laid 13 eggs. Table 3
gives comparative data on size of the eggs
and hatchlings of N. megalocephala, N.
natrix, and N. tessalata. These data show

megalocephala lays much bigger
and
its hatchlings are bigger in size
eggsthat N.

June 1990, laid a clutch of 11 eggs in
captivity on 20 August, 1990. The eggs
were incubated at 26-29° C and hatched on
29 September, 1990.
Diet.

—Natrix megalocephala feeds

Adults prey
mainly on amphibians.
actively on adult Bufo verrucosissimus. In

February 1992

Asiatic Herpetological Research

TABLE 2. Habitat descriptions of Natrix megalocephala populations.
Location of Population

Vol. 4, p. 49

Vol. 4, p. 50

Asiatic Herpetological Research

February 1992

TABLE 4. A comparison of morphology and pholidosis in Natrix natrix scutata, N. natrix persa, and N.
megalocephala.

Asiatic Herpetological Research

February 1992

Vol. 4, p. 51

FIG. 9. The heads of Natrix megalocephala (a, b, c) and Natrix natrix scutata (d, e, f) from sympatricpopulations at Stanitsa of Khamyshki, Krasnodarsky Territory, Ruissia.

other subspecies of Natrix natrix we did not
find hybrid characters in morphology(Intergrading features).

In all areas where

N. megalocephala comes into contact with
N. natrix and N. tessalata it has a distinct

morphological isolation (Table 4). Despite
evident phylogenetic relationship between
N. megalocephala and N. natrix it is'map*rprobable that these species diverged fromsome ancient ancestral form not on the
territory of the Caucasus Isthmus, butrather beyond it,

been an island.

when the Caucasus had

Supposedly, not less than

three faunogenetic centers contributed to theinvasion of Natrix species to the Caucasus
Asia Minor,
Isthmus in the Miocene:

Kirkand-Elbursk,

and

South

Europe(Vereshchagin, 1958). Apparantly the timeof invasion and distribution differed. The
fact is supported by the entire location of
habitats and interaction of such forms as N.
natrix persa, and N. natrix scutata which
form intergrading populations in theal
FlG 10 The heads of Natrix
fromandNa(rixna[rixSCMMa(c> d)b)hala (a>
tnc

pop^^

in the vacinity of Pitsunda,

Abkhazia,

Georgia,theforNatrixmegalocephala.

type

locality

Asiatic Herpetological ResearchVol. 4, p. 52

Caucasus, and N. megalocephala, which ineach overlapping area is distinctly separated
from N. natrix and N. tesselata.
evident that an ancestral form of N.
megalocephala came from Asia Minor in the
Miocene at the time the island of Caucasus
It isjoined Asia Minor (Vereshchagin, 1958).
The Pleiocene was the time of apparent
general invasion of N. megalocephala toforested subtropic areas of the Great
Caucasus and the western portion of the
Small Caucasus. At that time, this territory

February 1992

the basins of the Black and Caspian seas
(Kvasov, 1975) would not have been able
to be a barrier for such water-loving forms

natrix scutata to invade theas N.
Precaucasus. Alternation of regressions
and transgressions of these seas (Kvasov,
1975; Vereshchagin, 1958) might provide awave shaped invasion for N. natrix scutata
to the Caucasus. During interglacier andvegetation similar to the type that presently
exists in the Colchida refugia (Kharadze

particularly the postglacier Holocene
period, a shift of all vegetation belts in the
Caucasus occured (Vereshchagin, 1958).
This contributed to the isolation of
natrix scutata and probably N. natrix natrix.
In the Holocene, formation of habitats
occupied by Natrix species and subspecies

1974; Kholyavko et al., 1978).

Viperahad apparently been finished. The habitats

kaznakowi Nikolsky invaded the Caucasus

acquired contours similar to those presently
Arid areas of easternexisting.

wasincoveredmoisturewitha similar way.

Itslovingpresent habitatNrange ofandTuniyev, 1986b,
megalocephala (Orlov
1990). Abundant food items like various
Anura (Chkhikvadze, 1984) also
contributed to the broad distribution of thisspecies under the favorable conditions ofcoincides

with

the

.

evident that at theend of the Pleistocene, N. natrix persa
colonized the Talysh Mountains, presently
the Azerbaijan-Iran border. This species is
to a great extent associated with axerothermal regime. This is suggested by
the present range of the form which covers
semideserts and the dry steppes of eastern
Transcaucasus, Dagestan, and northern
Iran. During Pleistocene glaciation, which
covered high elevations of the Great andSmall Caucasus (Gvozdetsky 1954, 1958;
Markov et al., 1965), the habitat of N.

damp subtropics.

It ismegalocephala had apparantly split into: 1)
the Colchida portion where subtropicalvegetation was preserved even in the most
severe periods of glaciation (Adamyants,
1971; Vereshchagin, 1958) and 2) othersmaller spots lying between the Belaya
Laba (White Laba) and Malaya Laba (Small
Laba) rivers, in Borjomi Canyon and in thearea of Lagodekhi-Zakataly, all in Georgia.

N

Transcaucasia

did

not

allow

N

.

.

megalocephala to restore the eastern portionof its former distribution.

Analysis of the recent range of N.
megalocephala shows that the species does
not exceed the limits where the January
isotherm is -3 C° and precipitation is notless than 800
yearly (Gerasimov,1960). This along with the preference ofColchida subtropical vegetation in general
support the fact that this warm and water
dwelling species is ancient. Bartenev andReznikova (1935) observed a higher degreeof melanism in representatives of the
Colchida fauna, some snakes included. In
this area melanistic specimens of Coluber
najadum (Maim in and Orlov, 1977) andVipera kaznakowi are found. Black color
is also prevalent in the coloration of N.
megalocephala from the Colchida.

mm

It is

interesting to note that apart frommelanism both V. kaznakowi and N
megalocephala from the Colchida are.

characterized by:

1)

a big head, 2) a

massive body, and 3) a very

small

to

their

population

densitycomparedclosely related species.
In the Pleistocene N. natrix scutata
invaded the Precaucasus. Previously it wasprobably ousted by glaciers from theEuropean Plain to the lower areas of the

Don and Volga rivers. The Manychsky
Strait, which occasionallyused to connect

Acknowledgments

We would like to express our sincere
gratitude to Ilya S. Darevsky who aided usa lot in preparing this paper and toAsiatic Herpetological Research

February 1992

A. Danov and Dmitrey G.
Akimov who provided the drawings. Lena
Rostislav

Bortuleva translated the manuscript into
English.

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