FOUR NEW PUPFISHES OF THE GENUS CYPRINODON FROM MEXICO,
WITH A KEY TO THE C. EXIMIUS COMPLEX
Robert Rush Miller^
Abstract: The pupfishes (genus Cypiinodon) referable to the C. eximius complex comprise
seven species that are restricted to, or had their origin in, the Chihuahuan Desert region of
Mexico and adjacent parts of Texas and New Mexico. Four are described as new; the
remainder are C. eximius, C. atrorus, and C. latifasciatus. Most are of restricted distribution;
one is extinct and another may be. Keys, diagnoses, and ranges are given for each species
and all are illustrated. The distinctive morphometric characters of the new species are given.
Life colors and color patterns are important in distinguishing species.
More than fifty years ago, while on the staff of
the Field Museum of Natural History, Carl L.
Hubbs began to gather data for an intended
revision of the genus Cyprinodon (Hubbs, 1926:
17). He subsequently described the distinctive
Yucatan pupfish, C. variegatus artifrons (Hubbs,
1936: 223-225, pi. 6, figs. 1-5). About this time
I independently became interested in this genus
and we decided to work together on it (Hubbs
and Miller, 1941: 2). We did jointly describe a
new species from the Bahamas (Hubbs and Miller,
1942) but in the 1950's Carl turned over to me
all of his notes on Cyprinodon. These include
helpful information on some of the species that
are treated herein, including the significant
observation that colors and color pattern are
important specific traits.
The group of seven species (four new) in-
cluded in this paper comprises those pupfishes
believed to be closely related to Cyprinodon
eximius Girard, the most widely distributed species
of the complex. All are inhabitants of, or origi-
nated from ancestral stocks in, the Chihuahuan
Desert region (Basin and Range Province) of
northern Mexico and adjacent parts of Texas
and New Mexico (Miller, 1976b). They are
distinguished in the following key.
A KEY TO THE PUPFISHES OF THE
CYPRINODON EXIMIUS COMPLEX
1. a. Terminal black bar on caudal fin of nuptial
male broad, wider than pupil, about 1.2-1.6
in orbit 2
b. Terminal black bar on caudal fin of nuptial
male of usual width for Cyprinodon, subequal
to or less than diameter of pupil 6
2. a. Pelvic fins rather small and mandible long,
the pelvic length entering mandible length
more than 1.0 times C. alvarezi, n. sp.
(Fig. ID) El Potosi, Nuevo Leon
b. Pelvic fins not reduced and mandible not
4. a.
b.
elongated, the pelvic length entering mandible
length less than 1.0 times 3
3. a. Caudal fin of nuptial male with prominent
black spots or dashes on interradial membranes
of basal Va to % of fin, usually irregularly
arranged but sometimes aligned in about 3
vertical rows; terminal black bar immediately
preceded by a narrower light bar
__ C. eximius (Fig. lA) Rio Conchos Basin, etc.
b. Caudal fin of nuptial male without conspicu-
ous black markings on interradial membranes;
no light bar immediately preceding terminal
black bar 4
Gill rakers 12-17; mandibular pores 0-2;
scales around caudal peduncle usually 20
(uncommonly 16) C. nazas, n. sp.
(Fig. IC) Rio Nazas Basin, Santiaguillo Basin
Gill rakers 20-28; mandibular pores lacking;
caudal peduncle scales 16 (rarely 15 or
1 7 ) 5
5. a. Ocellus on dorsal fin lacking in both sexes;
lacrimal pores typically 3 (2-4); dorsal fin of
nuptial male not yellow or orange; body of
male with dark lateral stripe from behind eye
to caudal base, set off above by a narrow
silvery stripe (turquoise in life?) and below
by a broad yellowish stripe .... C. latifasciatus
(Fig. IG) Parras Basin, Coahuila
b. Ocellus present on dorsal fin of both sexes;
lacrimal pores lacking; dorsal fin of nuptial
male yellow or orange; body of male with 7-9
broad vertical bars C. atrorus (Fig. IB)
Cuatro Cienegas Basin, CoahuUa
6. a. Scales in lateral series 23 or 24; gill rakers
17-22; dorsal fin of nuptial male yellow;
vertebrae usually 25 C. macrolepis, n. sp.
(Fig. IF) Ojo Hacienda Dolores, Chihuahua
b. Scales in lateral series typically 25; gill rakers
12-15; dorsal fin of nuptial male not yellow;
vertebrae 26 or 27
BioStor
