Cyclura onchiopsis Cope
Cyclura nigerrima Cope, 1885:1005. Nomen nudum.
Cyclura onchiopsis Cope, 1885:1006. Type locality,
“Navassa Island.” Holotype, National Museum of
Natural History (USNM) 9977, collected in July
1878 by H. E. Klotz.
Cyclura nigerrima Cope, 1886:264. Type locality,
“Navassa Island.” Holotype, USNM 9974, collected
in July 1878 by G. A. Otis.
Cyclura cornuta onchiopsis: Schwartz and Thomas,
1975:112.
Navassan iguanas were regarded as a
distinct species related to Hispaniolan
Cyclura cornuta by Barbour and Noble
(1916), Schmidt (1919, 1921), and Cochran
(1941). Barbour (1937) considered them a
subspecies of C. cornuta and expressed
doubts about distinctiveness at even that
level. Mertens (1939) also suggested a subspecific
relationship that was accepted by
Schwartz and Thomas (1975). Schwartz and
Carey (1977) retained the trinomen but presented
numerous data suggestive of specific
distinctions. Meristic differences
include 4 or 6 scales between supraorbital
semicircles and the interparietal (modally 3
in C. cornuta), 7 supralabials to eye center
(modally 8 in C. cornuta), 33-38 femoral
pores (32-66 in C. cornuta), 38-41 fourth toe
subdigital scales (30-37 in C. cornuta), 7
median dorsal scales in the fifth caudal verticil
(one specimen only) (4-6, modally 4 in
C. cornuta), and 30-44 dorsolateral scales
(13-26 in C. cornuta) in a distance equal to
that between the naris and the eye.
Schwartz and Carey (1977) state: “It is even
conceivable that onchiopsis should be considered
a species distinct from C. cornuta on
the basis of this single character [distinctly
smaller dorsolateral scales] (plus perhaps
other modalities), but to do so would
obscure its obvious affinities with the latter
species.” Powell (1993) suggested that the
currently recognized subspecies of C. cornuta
be considered distinct species on the
assumption that allopatric populations formally
diagnosed as distinct are operationally
species. Based on the distinctions listed
above and the allopatry of the Navassan
population, I would argue that C. onchiopsis
is a species distinct from Hispaniolan C.
cornuta. By inference, I also recommend elevation
of the Mona Island population, C.
stejnegeri. Although no single character
state is as diagnostic as dorsolateral scale
size is for C. onchiopsis, allopatry and modal
differences suggest that the Mona Island
population is a full species.
Confusion about the name of the Navassan
population abounds. This form often
has been referred to in the literature as
Cyclura nigerrima or C. cornuta nigerrima
because Cope (1885) used both nigerrima
and onchiopsis, and used the former name
first. Schwartz and Carey (1997) correctly
noted that Cope (1885) failed to diagnose C.
nigerrima until 1886, rendering the 1885
usage a nomen nudum validated after C.
onchiopsis was formally and correctly diagnosed.
In addition to the brief descriptions provided
by Cope (1885, 1886), Barbour and
Noble (1916) and Schwartz and Carey
(1977) provided more detailed descriptions
(many others include Cyclura cornuta and
C. stejnegeri). Barbour and Noble (1916)
provided a line drawing. The largest specimen
examined by Schwartz and Carey
(1977) was a male with a SVL of 420 mm.
Thomas (1966) stated “As such large lizards
are very sensitive to the activities of
man, Cyclura may have been driven to
extinction on the island.” I saw no indication
that large iguanas were present and
the presumption that they are extinct must
stand. However, I disagree with Schwartz
and Carey’s (1977) statement that “the fate
of the Navassa lizards was sealed with the
introduction on that islet of cats or goats by
the lighthouse-keepers and their families.”
Instead, I suggest that the iguanas were
gone long before, as Ekman (1929) noted
that he saw none, nor had the lighthouse
keeper. Most likely, iguanas were extirpated
by habitat alteration, hunting for
food by workers, and introduced predators
during the mining period in the last half of
the nineteenth century.
www.uprm.edu/publications/cjs/Vol35a/p.1-13.pdf
