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PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, Supplement I 
tus was needed. They later obtained and examined 189 new specimens (Barbour and Davis, 1970), 
including 18 bats sampled from geographically intermediate areas in Colorado, and they agreed 
with the opinion of Findley and Jones (1967) that it was a subspecies based on numbers of premo¬ 
lars and length of the maxillary tooth row. 
The subspecies status was later questioned by Findley (1972) who used factor analysis, corre¬ 
lation, and distance analysis to perform a detailed quantitative assessment of 48 mensural charac¬ 
ters on 114 species, subspecies, or forms of bats of the genus Myotis worldwide. Myotis occultus 
and M. lucifugus carissima formed distinct subgroups apart from each other. Factor analysis 
showed M. occultus belonged to a subgroup with M. grisescens and five other species, and 
M. lucifugus carissima fell into a different subgroup with five different species (M /. carissima is 
the subspecies of M. lucifugus geographically closest to M. occultus to the north); similar separate 
groupings also appeared in correlation phenograms and distance phenograms (Findley, 1972). At 
this point, Findley concluded “Either occultus is a lucifugus which has converged strongly toward 
the grisescens group phenome, or the field relationships of carissima and occultus have not been 
fully elucidated” (Findley 1972:43). Harris (1974) speculated on the biogeographic history of the 
two forms, with alternative interpretations that hinged somewhat on the specific or subspecific sta¬ 
tus of M. occultus. 
A contrary view was taken by Hoffmeister (1986) who noted that the supposed intergradation 
seen by Findley and Jones (1967) was only based on four specimens and very few cranial meas¬ 
urements. Hoffmeister (1986) used as many as 27 cranial measurements and multi-dimensional 
analyses; based on patterns of morphological separation he concluded that “I am not convinced that 
occultus and lucifugus are conspecific. Tentatively, Myotis occultus is given specific status.” 
(Hoffmeister, 1986:76). However, Valdez et al. (1999a) came to the alternate conclusion based on 
protein electrophoresis of soft tissues. They examined 20 protein loci and found nine to be poly¬ 
morphic. They examined variation in these polymorphic loci among nine sample groups totaling 
142 bats. These sample groups corresponded to M. lucifugus carissima populations in southern 
Wyoming, M. occultus populations in New Mexico, and presumed intergrade populations (based 
on Findley and Jones [1967]) in southern Colorado (Valdez et al., 1999a). No fixed allelic differ¬ 
ences and high genetic similarity were found among these sample groups based on the protein elec¬ 
trophoresis, leading Valdez et al. (1999a) to conclude that the name occultus should be retained as 
a subspecies based primarily on morphological differences. 
Current Classification as a Full Species: Molecular analysis of the species question was 
taken a step further by sequencing 1,478 combined base pairs of the complete cytochrome oxidase 
II (COII) gene and the partial cytochrome-b gene (mitochondrial DNA) from a small subset of the 
individuals sampled by Valdez et al. (1999a) in New Mexico, southern Colorado, and Wyoming 
(Piaggio et al., 2002). Based on a series of complex phylogenetic analyses, Piaggio et al. 
(2002:391) concluded “Our results suggest that M. occultus represents an evolutionarily distinct 
monophyletic lineage and that it is separated from M. 1. carissima by sufficient genetic distance to 
be considered a separate species.” The samples from southern Colorado were genetically similar to 
M. occultus from elsewhere and distinct from M. lucifugus carissima, despite being morphologi¬ 
cally intermediate (Piaggio et al., 2002). As part of a larger dissertation on western species of 
Myotis, Dewey (2006) analyzed a subset of the genetic data as deposited in GenBank from the 
same eight specimens analyzed by Piaggio et al. (2002). This subset initially involved about 800 
base pairs from only the mitochondrial cytochrome b gene, with sequences subject to grouping 
through parsimony analysis. This smaller genetic data set led her to the conclusion that the sam¬ 
ples fell within M. lucifugus, but that they included four individuals that formed a well-supported 
clade (Dewey, 2006). However, these four individuals did not represent geographically distinct 
