9327

• UCREFRP Catalog Number: 9327
• Author: Starnes, W. C.
• USFW Year: 1995.
• Copyright Material: NO

The aforementioned genetically delimited group of samples in
the Culiacan, Sinaloa, Fuerte, Mayo, and portions of the Yaqui
drainage corresponds morphologically to fishes in Yaqui drainage
populations treated as "Gila robusta by Hendrickson et al.
(1980). They map the distribution, based on about 30 collections
examined, as occurring throughout most of the drainage in larger
streams or smaller tributaries with large permanent pools. Meek
(1902) described a taxon, Gila minacae, from Minaca on the upper
Rio Papigochic, Chihuahua, that is probably based on this form as
judged from his description, a subsequently published
illustration (Meek, 1904), and his recognition that it differed
from a sympatric form in that area, next discussed. Hendrickson
et al. (1980) placed minacae in the synonomy of G. robusta Baird
and Girard, 1853, described from the Colorado Basin, but genetic
evidence presented here strongly suggest that different taxa are
involved. Pending examination of the type (Field Museum Natural
History 3573), the nominal minacae Meek, 1902 may be the
appropriate epithet applicable to Gila populations examined
herein from the Culiacan drainage northward through the Mayo and
to many populations in the Yaqui drainage with the exception of
the following.
Specimens in the La Junta and Los Gavilones samples were
field identified by M.E. Douglas as "pulchra-like". Hendrickson
et al. (1980) report the occurrence of G. pulchra (as earlier
regarded by Meek, 1902,1904) at several localities in smaller
tributaries of the upper Papigochic system and note that is also
known from such habitats in the upper Mayo and Fuerte drainages
which are not populations sampled herein. Gila pulchra (Girard,
1857) was described from the Rio Conchos basin to the east of the
Yaqui, which is tributary to the Rio Grande and Gulf of Mexico;
Smith and Miller (1986) and Minckley et al. (1986) regard it as
endemic thereto and Yaqui populations as an undescribed taxon.
The allelic differences described above corroborate the
occurrence of broadly sympatric but wholly or partially
reproductively isolated forms in the eastern Yaqui drainage which
probably correspond in part to the,nominal menacae and pulchra or
the "pulchra-like" form (hereafter cf. pulchra). Unfortunately,
samples of pulchra from the Rio Conchos basin are not available
for comparison of alleles between that taxon and the Yaqui form.
Moreover, allelic differences between the La Junta and Los
Gavilones cf. pulchra samples from the upper Papigochic raise
questions as to whether a third taxon exists in the drainage or
if one may be a product of hybridization. The sharing of alleles
at two loci (bGAL,MPI-2) by the Los Gavilones sample but not the
La Junta sample with samples here referred to menacae may
indicate that the former is genotypically a product of past
introgression. However the Los Gavilones sample appears to be in
Hardy-Weinberg equilibrium (Table 4, Appendix) and therefore
hybridization may not be recent.
As noted previously, UPGMA grouped cf. pulchra samples from
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