7345

• UCREFRP Catalog Number: 7345
• Author: Wick, E. J.
• USFW Year: 1975.
• Copyright Material: NO

TAXONOMY
DIST] NGUISHING CHARACTERISTICS:
Characteristics which most typify G. cypha are;
1. An abrupt nuchal hump in the occiput region.
2. A fleshy snout projecting well beyond the jaw
with subterminal mouth.
3. The caudal peduncle thickness and upper jaw length
intermediate between the three species.
ti-
4. A significantly smaller eye diameter of 6.0-7.1, mm.
The more pronounced the nuchal hump and the more closely
specimens resemble key characteristics, the purer the species.
We must continually keep in mind that distinction between 17, ry-ha
and G. elegans is not clear due to introg?ressive ryrridi:.at: m.
However, it is generally agreed that the two species, G. cyrha,
and G. elerans, are two valid species (personal conversat.ior with
Dr. Behnke). G. cypha perhaps evolved from G. elerAns a' n earlier
time, became isolated by past environmental- conditions, and a6apt.ed
to torrential canyon areas of the Colorado River. More recently,
because of changing habitat and reduced numbers, hybridization has
taken place.
SPK17*1,1S' TAXONO:?IC CHARACTERISTICS:
Of the four key characters, our specimen qualifies as Gila
cypha on all measurements and characteristics (see Tab.1) ;,s
noted in Table I, snout length was of some concern. As shown in.
photograph, Figure 3 (page 7), the snout is somewhat shcrter and
head depth in posterior region was thicker iiu?ltoe specimer-,., figures
I and II. Specimen's abrupt hump could be considered intermediate
between two top specimens in Figure IT.
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