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PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 64, Supplement 1 
scorpion known from the Mojave Desert, Larca aalbui, is related to cave-adapted species in Ari¬ 
zona and Texas. 
In this paper the top 20 California caves for biodiversity are found in many regions, which rank 
as follows: Sierra Nevada South 9, Sierra Nevada North 6, Klamath and Marble Mountains 2, Bay 
Area/Delta 2, and Lava Flows North 1. Overall the Sierra Nevada has the largest share of high bio¬ 
diversity caves, the northern half with the most single-site endemics, but the southern half with 
individual caves having higher site endemism and overall biodiversity. Bay Area/Delta has two 
very different caves with high biodiversity. Klamath and Marble Mountains (Samwel Cave and 
Shasta Caverns) have outstanding biodiversity. Subway Cave in Lava Flows North is remarkable 
in ranking 18 th in biodiversity despite being in a lava flow less than 2,000 years old, which sug¬ 
gests that some of the troglobites, like Plumatyla humerosa, have invaded caves and cracks from 
adjacent, older lava flows, analogous to the lava tube fauna in Hawaii (Howarth 1972). As in other 
high biodiversity caves, tree roots enhance energy inputs and habitat complexity. 
With the data then available, Elliott (2007) ranked California as ninth among U.S. states in 
subterranean biodiversity, with 7 phreatobites, 8 stygobites, and 42 troglobites, a total of 47 obli¬ 
gate subterranean species, which this paper has increased to 146 species. Table 25 is a comparison 
of numbers of obligate subterranean species in leading states, with data sources cited. California 
currently ranks third nationally if phreatobites are included (phreatobite data are not easily avail¬ 
able from other states and definitions vary among authors.) These rankings are not precise, but 
California’s subterranean biodiversity is high on the national and the continental scale. 
Many mechanisms have allowed cavemicoles to become isolated in California’s caves. We 
have presented examples of geology, elevation, drainage basins, aridity, and climate change. In his 
1973 paper on lava tube faunas in the western U.S., Peck said, “Among the terrestrial invertebrate 
troglobites and obligate troglophiles, at least, the cave occupation seems certainly to have been 
motivated by a search for cool, moist habitats. Such habitats are those occupied by the species most 
closely related to the troglobites. This conclusion is reinforced by the observation that caves with 
cooler air and with standing water or ice contain a richer fauna . . . Much of the fauna probably 
Table 25. Comparison of numbers of obligate subterranean species in leading U.S. cave states. 
State 
Ref. 
No. sites 
sampled 
All Species 
Phreatobites 
Stygobites 
Troglobites 
Obligate 
Sub. Species 
Rank 
Texas 
Reddell pers. comm. 
2016 
4,092 
1,519 
42 
49 
200 
291 
1 
Tennessee 
Niemiller and Zigler 
2013 
661 
40 
160 
200 
2 
California 
This study 
1,293 
1,366 
32 
12 
102 
146 
3 
Alabama 
Elliott 2007 
2 
23 
120 
145 
4 
Virginia 
Elliott 2007 
12 
38 
89 
139 
5 
Kentucky 
Elliott 2007 
0 
29 
90 
119 
6 
West Virginia 
Fong et al. 2007 
282 
33 
53 
86 
7 
Missouri 
Elliott 2007 
960 
927 
13 
36 
33 
82 
8 
Arkansas 
Graening et al. 2011 
72 
9 
Indiana 
Elliott 2007 
3 
22 
32 
57 
10 
Oklahoma 
Graening et al. 2011 
48 
11 
Georgia 
Elliott 2007 
0 
16 
24 
40 
12 
