Iguana 10.3 color covers (Page C1)


A
lthough few iguanas in the genus
Ctenosaura are actually black (this
occurs only in some individual C. acan-
thura and C. pectinata), one of the com-

mon names by which they are collectively known
is “Black Iguanas.” This name is actually mislead-
ing when referring to some of the smaller, more
colorful species (e.g., C. alfredschmidti, C. defen-
sor, and C. flavidorsalis). Another common name
used in English for species in this genus is “Spiny-
tailed Iguanas.”

In Central America, Black Iguanas are called
“Garrobos” or “Iguanas Negras.” Local inhabi-
tants of the Islas de la Bahia (Utila, Roatan, and
Guanaja), located off the northern coast of
Honduras, call the species that occur there,
“Wishiwillies,” and, on the Isla de la Providencia,
they are known as “Ishillies.”

The phylogenetic relationships and taxonomy
of iguanas have provoked considerable controversy
in recent years. In 1988, eight monophyletic2

groups were shown to exist within what had been
considered the Family Iguanidae. Shortly there-
after, these were elevated to eight distinct families,
largely because no evidence could be found for the
monophyly of the entire family. This new classifi-
cation was heavily criticized and eventually
reversed on the basis of molecular genetic studies.
However, after a very recent revision of the origi-
nal study, which, among other things, now
showed eleven monophyletic groups of iguanian
lizards, the controversy continues. Some experts

believe that all pleurodont iguanian lizards should
be included in a single family (Iguanidae sensu lato)
and that the monophyletic subgroupings should
be treated as subfamilies (e.g., the subfamily
Iguaninae). In contrast, other experts think that
real relationships are better portrayed by recogniz-
ing eleven separate families, one of which includes
the “true” iguanas (Iguanidae sensu stricto).

Accordingly, lizards in the genus Ctenosaura
are placed either in the subfamily Iguaninae (in the
Family Iguanidae sensu lato) or in the Family
Iguanidae (sensu stricto).  Regardless of taxonomic
rank, this group also includes the Marine Iguanas
(Amblyrhynchus), Rock Iguanas (Cyclura), Fiji
Iguanas (Brachylophus), Galapagos Land Iguanas
(Conolophus), Desert Iguanas (Dipsosaurus), Green
Iguanas (Iguana), and Chuckwallas (Sauromalus).
The genus Ctenosaura is differentiated from the
other genera within the family (or subfamily) by
the presence of an extremely long subocular scale
and whorls of enlarged, spiky scales on the tail.
Ctenosaurs are most closely related to lizards in
the genera Iguana and Cyclura.

In recent years, tremendous advances have
been made in the systematics of Ctenosaura.
Seventeen species are currently recognized:
C. acanthura, C. alfredschmidti, C. bakeri, 
C. clarki, C. conspicuosa, C. defensor, C. flavidor-
salis, C. hemilopha, C. macrolopha, C. melanos-
terna, C. nolascensis, C. oaxacana, C. oedirhina, 
C. palearis, C. pectinata, C. quinquecarinata, and
C. similis. As recently as 1928, 13 species were rec-
ognized, but subsequent workers determined that
the species C. brachylopha, C. brevirostris, and 
C. parkeri were actually C. pectinata; and, more
recently, C. erythromelas was subsumed within 
C. defensor, reducing the number to only nine.
More recently described species (the most recent in
2001) have elevated the number to the current 17.

Black Iguanas: 
Name and Systematics1

Gunther Köhler1, AJ Gutman2, and Robert Powell3

1Forschungsinstitut Senckenberg, Frankfurt a/M., Germany; 
2West Hartford, Connecticut, USA; 

3Department of Biology, Avila University, Kansas City, Missouri, USA.

79IGUANASeptember 2003

1 Adapted from Köhler, G. 2002. Schwarzleguane.
Lebensweise, Pflege, Zucht. Herpeton Verlag Elke Köhler,
Offenbach, Germany. Translated from German by AJ
Gutman with additional commentary by Robert Powell.
2 A “monophyletic” group includes an ancestor and all of
its descendants.



In the past, some species (C. bakeri, 
C. palearis, C. quinquecarinata, C. clarki, and 
C. defensor) were split off from Ctenosaura and
placed in a separate genus, Enyaliosaurus, but this
division is no longer widely recognized. More
recent studies, based on genetic and morphologi-
cal data, have presented an hypothesis of relation-
ships within the genus Ctenosaura that recognizes
three monophyletic species groups designated as
subgenera (Ctenosaura, Enyaliosaurus, and
Loganiosaura).

The subgenus Ctenosaura includes the larger
species, C. acanthura, C. conspicuosa, C. hemilopha,

C. macrolopha, C. nolascensis, C, pectinata, and 
C. similis, all of which lack the enlarged, heavily
keeled to spiky scales on the dorsal surface of the
upper thigh (along with some other characters).
The males in these species attain total lengths of
over 1 meter. The morphological criteria con-
tained in the initial descriptions of three of these
larger species, C. acanthura, C. pectinata, and 
C. similis, were apparently quite variable and
resulted in no definitive morphological characters
by which these three taxa could be distinguished
from one another. As recently as ten years ago,
some authorities suggested that further study of

80 IGUANA Volume 10, Number 3



the status of the C. similis-acanthura-pectinata
group would reveal that only a single species
occurred from southern Sinaloa (Mexico) all the
way to Panama. This assumption proved to be
incorrect. Morphological and genetic studies have
shown that these three species are all valid and can
be distinguished by scalation and coloration. Field
studies also have provided a more detailed picture
of the geographic distribution of the three species
in the Isthmus of Tehuantepec, where their ranges
approach each other.

The subgenus Loganiosaura includes the
medium-sized species, C. bakeri, C. melanosterna,
C. oedirhina, and C. palearis, which attain maxi-
mum total lengths of 80 cm. Of these species, 
C. bakeri, C. melanosterna, and C. palearis possess
a well-developed pendulous dewlap, whereas 
C. oedirhina has a transverse gular fold. The
species in this subgenus also differ from other
ctenosaurs in several skull characters, which rein-
forces the view that this group is monophyletic.

The subgenus Enyaliosaurus includes the small
species, C. alfredschmidti, C. clarki, C. defensor, 
C. flavidorsalis, C. oaxacana, and C. quinquecari-
nata. These species are characterized, among other
things, by a reduction of the number of postmen-
tal scales (from four to two) and possession of a
relatively short, very spiky tail, which, at its widest
point, is broader than it is high. Within this sub-
genus, C. alfredschmidti, C. clarki, and C. defensor
are notable for the reduction of the parietal eye,
which is barely distinguishable with the naked eye
(this trait is very evident in other species as the dis-
tinct spot in the middle of the parietal scale on the
top of the head). These three species also have
whorls of well-developed, enlarged, spiky scales all
the way to the tips of their tails (approximately the
distal third of the tail is without whorls in the other
species). 

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81IGUANASeptember 2003