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Cave-dwelling invertebrates of Grand Canyon National Park

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Abstract and Figures

Cave ecosystems are among the most fragile ecosystems on Earth (Elliott 2000; Hamilton-Smith and Eberhard 2000) due, in part, to the sensitivity of cave-dwelling organisms to disturbance. Because many troglomorphic taxa (obligate cave-dwelling organisms) are endemic to a single cave or region (Reddell 1994; Culver et al. 2000; Christman et al. 2005), and are generally characterized by low population numbers (Mitchell 1970; Krajick 2001), many populations are consid-ered imperiled (Reddell 1994; Culver et al. 2000). Most studies of cave invertebrates have been simple inventories, with relatively little data collected on species and commu-nity ecology. For this study we have synthesized all known information on cave-dwelling inver-tebrates in Grand Canyon National Park (GRCA). There is a paucity of knowledge about caves in GRCA, as well as other areas on the southern Colorado Plateau. The avail-able information is limited to a few intensive studies (where invertebrates were collected and identified) and cave trip reports (where invertebrates were documented visually). Here we determine the extent of knowledge concerning cave-dwelling invertebrate fauna, identify the seemingly most common cave-dwelling invertebrates, and present our preliminary understanding of invertebrate diversity and endemism in Grand Canyon caves. METHODS We conducted a literature review that in-cludes all published literature, obtained primarily through Northern Arizona Uni-versity's Cline Library and Internet searches, and unpublished literature and cave trip re-ports on file at GRCA Museum Collections. We did not include reports supported by little or no documentation or those in which invertebrate observations are not well described (i.e., above the family taxonomic level). We divided Grand Canyon cave inverte-brates into five cavernicole (cave-dwelling organism) groups and one special case cate-gory: (1) Troglobites, which are obligatory terrestrial cave-adapted species occurring only in caves or similar subterranean habi-tats, (2) troglophiles, which are species occurring facultatively within caves and completing their life cycles there, but prob-ably also occurring in surface environments, (3) trogloxenes, which are taxa that live in caves for shelter and potentially favorable microclimate but that return to epigean habitats to forage (refer to Barr 1968), (4) stygobites, which are obligatory aquatic cave-adapted organisms (refer to Culver and White 2005), (5) unknown cavernicoles, which are organisms not categorized due to a lack of information, and (6) special cases, which include organisms brought into the cave by vertebrate species. Additionally, be-cause organisms known to feed in guano deposits are of interest to cave ecologists, we included the subgroup guanophiles. Troglo-bites, troglophiles, and trogloxenes are the groups generally known to contain guano-philes. Current taxonomy was verified for most invertebrates using the Integrated Tax-onomic Information System (http://www .itis.gov) and Triplehorn and Johnson (2005).
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CAVE-DWELLING INVERTEBRATES OF
GRAND CANYON NATIONAL PARK
J. Judson Wynne, Charles A. Drost, Neil S. Cobb, and John R. Rihs
Cave ecosystems are among the most fragile
ecosystems on Earth (Elliott 2000; Hamilton-
Smith and Eberhard 2000) due, in part, to
the sensitivity of cave-dwelling organisms to
disturbance. Because many troglomorphic
taxa (obligate cave-dwelling organisms) are
endemic to a single cave or region (Reddell
1994; Culver et al. 2000; Christman et al.
2005), and are generally characterized by
low population numbers (Mitchell 1970;
Krajick 2001), many populations are consid-
ered imperiled (Reddell 1994; Culver et al.
2000). Most studies of cave invertebrates
have been simple inventories, with relatively
little data collected on species and commu-
nity ecology.
For this study we have synthesized all
known information on cave-dwelling inver-
tebrates in Grand Canyon National Park
(GRCA). There is a paucity of knowledge
about caves in GRCA, as well as other areas
on the southern Colorado Plateau. The avail-
able information is limited to a few intensive
studies (where invertebrates were collected
and identified) and cave trip reports (where
invertebrates were documented visually).
Here we determine the extent of knowledge
concerning cave-dwelling invertebrate
fauna, identify the seemingly most common
cave-dwelling invertebrates, and present our
preliminary understanding of invertebrate
diversity and endemism in Grand Canyon
caves.
METHODS
We conducted a literature review that in-
cludes all published literature, obtained
primarily through Northern Arizona Uni-
versity’s Cline Library and Internet searches,
and unpublished literature and cave trip re-
ports on file at GRCA Museum Collections.
We did not include reports supported by
little or no documentation or those in which
invertebrate observations are not well
described (i.e., above the family taxonomic
level).
We divided Grand Canyon cave inverte-
brates into five cavernicole (cave-dwelling
organism) groups and one special case cate-
gory: (1) Troglobites, which are obligatory
terrestrial cave-adapted species occurring
only in caves or similar subterranean habi-
tats, (2) troglophiles, which are species
occurring facultatively within caves and
completing their life cycles there, but prob-
ably also occurring in surface environments,
(3) trogloxenes, which are taxa that live in
caves for shelter and potentially favorable
microclimate but that return to epigean
habitats to forage (refer to Barr 1968), (4)
stygobites, which are obligatory aquatic
cave-adapted organisms (refer to Culver and
White 2005), (5) unknown cavernicoles,
which are organisms not categorized due to
a lack of information, and (6) special cases,
which include organisms brought into the
cave by vertebrate species. Additionally, be-
cause organisms known to feed in guano
deposits are of interest to cave ecologists, we
included the subgroup guanophiles. Troglo-
bites, troglophiles, and trogloxenes are the
groups generally known to contain guano-
philes. Current taxonomy was verified for
most invertebrates using the Integrated Tax-
onomic Information System (http://www
.itis.gov) and Triplehorn and Johnson (2005).
Wynne, J.J., C.A. Drost, N.S. Cobb and J.R. Rihs. 2007. Cave-dwelling Invertebrate Fauna of Grand
Canyon National Park, Arizona. In Proceedings of the 8th Biennial Conference of Research on the
Colorado Plateau (C. van Riper and M. Sogge, Eds). University of Arizona Press, Tucson, pp. 235-246.
236 Wynne, Drost, Cobb, and Rihs
RESULTS
We reviewed the results of nine studies
(conducted between 1975 and 2001) repre-
senting surveys of 15 GRCA caves (Table 1).
These studies identified approximately 37
cave-dwelling invertebrates that are known
to occur in Grand Canyon caves: 3 troglo-
bites, 6 trogloxenes, 14 troglophiles, 1 sty-
gobite, 10 unknown cavernicoles, and 3
species representing special cases. Voucher
specimens were used to identify 30 (~81%)
of theses invertebrates. Of the unknown
cavernicoles, Peck (1978) has suggested that
one of these might be troglomorphic. Two
species are tentatively considered guano-
philes—one Collembola (Tomocerus sp.) and
one troglobitic Leiodid beetle (Ptomaphagus
cocytus).
In four of the nine studies that we re-
viewed—Welbourn (1978), Peck (1980), Roth
(1982), and Drost and Blinn (1997)—the
researchers collected specimens, whereas
Triplehorn (1975) analyzed and described
specimens collected by another researcher.
Welbourn (1978) conducted a regional study
of Horseshoe Mesa caves, where he identi-
fied 12 invertebrates from eight caves. Peck
(1980) identified 15 species (including three
previously undescribed troglobitic species)
from three stream caves (Roaring Springs,
Tapeats, and Thunder River Caves). Roth
(1982) identified one pholcid spider (Psilo-
chorus sp.) from one cave. Drost and Blinn
(1997) identified 19 species from Roaring
Springs Cave, including one previously
undescribed stygobitic amphipod. Based on
specimens from three caves within Grand
Canyon, Triplehorn (1975) described a new
tenebrionid beetle species, Eleodes leptoselis.
Specimens were collected from 13 of the 15
caves considered for this review.
Taxonomically, the most diverse groups
in the known Grand Canyon cave inverte-
brate fauna are spiders (order Araneae, at
least eight species), beetles (order Coleop-
tera, four species, including one special
case), and flies (order Diptera, at least two
species; Tables 2 and 3). Other groups of
particular interest due to their ecological
and evolutionary relationship to cave envi-
ronments include amphipods (one endemic
deep-cave species, Stygobromus blinni), har-
vestmen (order Opiliones), mites (order
Acari, one potentially cave-adapted species),
springtails (order Collembola, two species,
at least one of which is cave-adapted), and
diplurans (order Diplura, with at least one
potentially cave-adapted species).
Spiders and beetles are the most wide-
spread invertebrates. There were 14 occur-
rences of spiders in 12 of 15 caves sampled,
and 12 occurrences of beetles in 10 of 15
caves (Table 2). Cave crickets (order Orthop-
tera, family Raphidophoridae) were also
widespread, occurring in 10 of 15 caves. The
two most widespread species were the cave
cricket Ceuthophilus yavapai and the tenebri-
onid beetle Eleodes leptoselis, occurring in
eight and six caves, respectively.
Specimens that we examined from Grand
Canyon caves also yielded five undescribed
species, four potentially undescribed spe-
cies, and two new state records. The unde-
scribed and newly described species consist
of one stygobite (Stygobromus blinni Wang
and Holsinger 2001; Figure 1) and three
troglobites (Telema sp. nov., Tomocerus sp.
nov., and Ptomaphagus cocytus nov.) from
Roaring Springs and Tapeats Caves (Peck
1980; Drost and Blinn 1997), and one trog-
lophile (Eleodes [Caverneleodes] leptoselis sp.
nov.) from Cave of the Domes (Triplehorn
1975; Welbourn 1978; Hill et al. 1998), Cave
68-Olie (Triplehorn 1975), Tse An Cho Cave
(Triplehorn 1975; Welbourn 1978), and
potentially from Land’s End Cave, Scorpion
Cave, and Tuning Fork Cave (Welbourn
1978). All of these species are believed to be
endemic to the Grand Canyon. Four species
have not been identified and may represent
new and endemic species; these comprise a
mite (Rhagidia cf. hilli), a dipluran (Haplocam-
pa sp.), a collembolan (Entomobrya cf. cali-
fornica), and a tineid moth (Tinea nov. sp.).
Two caddisfly species (Micrasema onisca and
Lepidostoma apornum) documented in Roar-
ing Springs Cave establish new records in
Arizona (Drost and Blinn 1997). Also, Telema
sp. nov. is the only known troglobitic spider
in Arizona (Peck 1980).
Table 1. Invertebrate inventories by cave and research effort in Grand Canyon National Park.
Drost & Blinn Hill et al. Hill et al. Hill et al. Pape Peck Roth Triplehorn Welbourn
Study (1997)1(1998) (2000) (2001) (1998) (1980)1(1982)1(1975)1,2 (1976)1
Babylon Cave X X
Bat Cave X X
Cave 68-Olie X
Cave of the Domes X X X
Christmas Tree Cave X
Crystal Forest Cave X X
Land’s End Cave X
Middle Cave X
Rampart Cave
Roaring Springs Cave X X
Scorpion Cave X
Tapeats Cave X
Thunder River Cave X
Tse An Cho Cave X X
Tse’an Kaetan Cave X
Tuning Fork Cave X
1 Studies in which researchers collected voucher specimens.
2 Fieldwork was not conducted during this effort; rather, a new species was described.
Table 2. Invertebrates recorded from selected caves in Grand Canyon National Park. When invertebrates were not identified to species level, the lowest
taxonomic level noted in the original source is listed.
Cave Cave of Christmas Crystal Land’s
Babylon Bat 68- the Tree Forest End Middle
Cave Cave Olie Domes Cave Cave Cave Cave
Stygobromus blinni –––––– –
Loxosceles sp. –X––––
Telema sp. ––––––
Kibramoa suprenansX
Psilochorus sp. –X––X
Achaearanea canionis –––––– –
Lepthyphantes sp. ––––––
Selenops sp. –X–––X
Leiobunum cf. townsendii –– –X–X –
Neoallochernes stercoreusX
Family Anystidae X X
Chiroptonyssus robustipesX
Rhagidia cf. hilli –––– –– –
Entomobrya californica?–X
Tomocerus sp. –– –– ––
Haplocampa sp. –––– ––
Ceuthophilus yavapai X–X–X XX
Hesperoperla pacifica –––––– –
Psyllipsocus ramburii –––––– –
Psyllipsocus sp. XX–X––
Bembidion sp. ––––––
Ptomaphagus cocytus –––––– –
Eschatomoxys sp. –X––––
Eleodes (Caverneleodes) leptoselis ––XX–– X
Smicronyx imbricatusX
Sceliphron sp. or Chalybion sp. X
Micrasema onisca –––––
Lepidostoma apornum –––––– –
Tinea n. sp. X X
Pronoctua typica –––––
Family Arctiidae?
Sternopsylla texanaX
Family Tipulidae X
Limonia sp. ––––––
Tipula (Bellardina) rupicola –––––– –
Mycetophila sp.
Sciara sp.
Table 2 (continued)
Roaring Thunder Tse An Tse’an Tuning
Springs Scorpion Tapeats River Cho Kaetan Fork
Cave Cave Cave Cave Cave Cave Cave
Stygobromus blinni X––––––
Loxosceles sp. X––X–––
Telema sp. X––––––
Kibramoa suprenans –––––––
Psilochorus sp. –––––––
Achaearanea canionis X–X––––
Lepthyphantes sp. X––––––
Selenops sp. –––––––
Leiobunum cf. townsendii X–––––X
Neoallochernes stercoreus –––––––
Family Anystidae ––––––X
Chiroptonyssus robustipes –––––––
Rhagidia cf. hilli X––––––
Entomobrya californica? ––––––X
Tomocerus sp. X––––––
Haplocampa sp. X–X––––
Ceuthophilus yavapai XX– – XXX
Hesperoperla pacifica X––––––
Psyllipsocus ramburii ––X–X–X
Psyllipsocus sp. –––––––
Bembidion sp. X––––––
Ptomaphagus cocytus X–X––––
Eschatomoxys sp. –––X–––
Eleodes (Caverneleodes) leptoselis –X––X–X
Smicronyx imbricatus –––––––
Sceliphron sp. or Chalybion sp. –––––––
Micrasema onisca X––––––
Lepidostoma apornum X––––––
Tinea n. sp. –––––––
Pronoctua typica X––––––
Family Arctiidae? –––––X
Sternopsylla texana –––––––
Family Tipulidae –––––––
Limonia sp. X––––––
Tipula (Bellardina) rupicola X––––––
Mycetophila sp. X ––––––
Sciara sp. X ––––
240 Wynne, Drost, Cobb, and Rihs
Table 3. Annotated list of cave invertebrates in Grand Canyon National Park.
Class Crustacea
Order Amphipoda
Family Crangonyctidae
Stygobromus blinni Wang and Holsinger 2001. Stygobite. Roaring Springs Cave (Drost and Blinn 1997).
This cave-adapted species was found in the middle and deep zone of the cave. Stygobromus blinni is
currently known only from Roaring Springs Cave and its associated waters.
Class Arachnida
Order Araneae
Welbourn (1978) noted unidentified spiders in Babylon Cave, Cave of the Domes, Crystal Forest Cave,
Middle Cave, Scorpion Cave, Tse An Cho Cave, and Tuning Fork Cave. Welbourn (1978) collected
several specimens along the walls and ceilings, which may represent at least two species. These spiders
were collected within the twilight and near the edge of the dark zone (Welbourn 1978). Similarly, Hill
et al. (1998) identified a medium-sized, tan, velvety spider near a wet area near the back of Crystal
Forest Cave. These unidentified spiders may or may not be among the species listed below.
Family Loxoscelidae
Loxosceles sp. Undetermined species. Troglophile (Peck 1980). Bat Cave (Pape 1998; Hill et al. 2001),
Roaring Springs Cave (Drost and Blinn 1997), and Thunder River Cave (Peck 1980). One individual
was collected within the dark zone of Bat Cave (Pape 1998). Hill et al. (2001) also identified a Loxosceles
sp. during their Bat Cave survey. A Loxosceles sp. was also observed within the twilight zone of Roaring
Springs Cave (Drost and Blinn 1997). In Thunder River Cave, Peck (1980) identified a Loxosceles sp. in
webs along the base of the walls near guano deposits.
Family Telemidae
Telema sp. Undescribed troglobite (Peck 1980). Roaring Springs Cave (Peck 1980). Peck suggested that
this is the only known cave-adapted spider in Arizona.
Family Plectreuridae
Kibramoa suprenans Chamberlin 1920. Troglophile (Pape 1998). Bat Cave (Pape 1998). Pape observed
webs of this species along the base of cave walls, in rock piles, and along walkway and machinery from
abandoned guano mining operations.
Family Pholcidae
Psilochorus sp. Troglophile (Pape 1998). Christmas Tree Cave (Roth 1982) and Bat Cave (Pape 1998).
Pape suggested that a small population exists within Bat Cave.
Family Theridiidae
Achaearanea canionis Chamberlin and Gertsch. Troglophile/trogloxene (Peck 1980; unknown caverni-
cole). Tapeats Cave (Peck 1980) and Roaring Springs Cave (Peck 1980; Drost and Blinn 1997). This
species was observed within the twilight zone of Roaring Springs Cave (Drost and Blinn 1997). It is
known to occur in caves, as well as more mesic epigean environments in Arizona, California, New
Mexico, and Utah, and “other species within this genus are frequently found near cave entrances”
(Peck 1980). We assume that Peck (1980) and Drost and Blinn (1997) observed the same species.
Family Linyphiidae
Lepthyphantes sp. Unknown cavernicole. Roaring Springs Cave (Drost and Blinn 1997). This species was
observed within the twilight zone of the cave.
Family Selenopidae
Selenops sp. Troglophile (Pape 1998). Bat Cave (Pape 1998) and Crystal Forest Cave (Hill et al. 1998).
Several molts of this species were observed within the cave twilight zone (Pape 1998). Pape suggested
that their occurrence was probably deep enough within the cave to prey upon guanophiles.
Family Thomisidae
Unidentified genus and species. Unknown cavernicole. Hill et al. (1998) tentatively identified a spider
photographed in Crystal Forest Cave as a crab spider, either a trogloxene or troglophile.
Order Opiliones
Family Sclerosomatidae
Leiobunum cf. townsendii Weed. Troglobite/troglophile (Peck 1980; troglophile). Roaring Springs Cave
(Peck 1980; Drost and Blinn 1997), Cave of the Domes, Tuning Fork Cave (Welbourn 1978), and Crystal
Forest Cave (Welbourn 1978; Hill et al. 1998). Drost and Blinn (1997) observed Leiobunum sp. within the
twilight zone of Roaring Springs Cave. This is likely the same species identified by Peck (1980). Wel-
bourn (1978) suggested that harvestmen are not common in large numbers in Horseshoe Mesa caves.
Wynne, Drost, Cobb, and Rihs 241
In Crystal Forest Cave, Hill et al. (1998) identified piles of legs, which they incorrectly identified as
“Phalangida.” Species of Leiobunum are common in the U.S. Southwest, and members of this group are
frequently encountered in and around caves (Peck 1980). This species is widely known to den in the
light to twilight zones of caves in the Southwest (W. Shear, personal communication; Wynne, personal
observation). Thus, we consider this a troglophilic species.
Order Pseudoscorpiones
Family Chernetidae
Neoallochernes stercoreus Turk 1949. Unknown cavernicole. Bat Cave (Pape 1998). Pape suggested that
this species is often associated with active Mexican free-tailed bat (Tadarida brasiliensis) guano deposits.
Order Acari
Family Anystidae
Undetermined genus and species. Trogloxene? (Welbourn 1978; unknown cavernicole). Crystal Forest
Cave (Welbourn 1978; Hill et al. 1998), Middle Cave, and Tuning Fork Cave (Welbourn 1978). Anystids
were observed under rocks near the edge of the twilight zone (Welbourn 1978). In Crystal Forest Cave,
Hill et al. (1998) observed a small gray mite “running” around the floor “in a wet area near a speleo-
them drip” and suggested that it was the same anystid observed by Welbourn (1978). Predacious mites
of this family are known to occur within the twilight zones of other Arizona and New Mexico caves
(Welbourn 1978). Welbourn indicated that these mites have been observed in large numbers beneath
rocks within Wupatki National Monument earth cracks.
Family Macronyssidae
Chiroptonyssus robustipes Ewing. Special case: ectoparasite. Bat Cave (Pape 1998). This species is an
obligate parasite on the Mexican free-tailed bat (Tadarida brasiliensis).
Family Rhagidiidae
Rhagidia cf. hilli Strandtmann 1971. Troglobite/troglophile (Peck 1980; unknown cavernicole). Roaring
Springs Cave (Peck 1980; Drost and Blinn 1997). Peck indicated that this genus occurs in other caves in
the western United States and Mexico.
Class Collembola
Order Entomobryomorpha
Family Entomobryidae
Entomobrya cf. californica Schott 1891. Troglophile (Welbourn 1978). Cave of the Domes and Tuning
Fork Cave (Welbourn 1978). This species was restricted to the moist wet areas of Horseshoe Mesa caves
(Welbourn 1978). K. Christiansen suggested that the Collembolan observed in Horseshoe Mesa caves
may be different from other E. californica and that further study was needed (Welbourn 1978).
Tomocerus sp. Undescribed troglobite (Peck 1980). Guanophile? Roaring Springs Cave (Peck 1980; Drost
and Blinn 1997). Peck (1980) indicated that several individuals were observed within “scattered mouse
(bat?) droppings on moist sand” within the cave’s dark zone. Drost and Blinn (1997) collected this
species within the cave’s twilight zone. Four species within this genus are known from caves—three
from the United States (Kentucky, Illinois, Missouri, and New Mexico) and one from Japan (Peck 1980).
Order Diplura
Family Campodeidae
Haplocampa sp. Troglobite/troglophile (Peck 1980; unknown cavernicole). Tapeats Cave (Peck 1980),
and probably Roaring Springs Cave (Drost and Blinn 1997). In Tapeats Cave, three specimens were
found on scat on “silt along a wall in the main trunk passage” (Peck 1980). Peck indicated that various
genera of this family are commonly observed in caves. Drost and Blinn (1997) observed diplurans
within the dark zone of Roaring Springs; two individuals were found dead and in poor condition
within a small pool, and were not identifiable beyond family.
Class Insecta
Order Orthoptera
Family Rhaphidophoridae
Ceuthophilus yavapai Hubbell 1936. Trogloxene (Welbourn 1978; Peck 1980). Cave of the Domes
(Welbourn 1978; Hill et al. 1998), Babylon Cave, Crystal Forest Cave, Land’s End Cave, Middle Cave,
Scorpion Cave, Tse An Cho Cave, Tuning Fork Cave (Welbourn 1978), Roaring Springs Cave (Peck
1980; Drost and Blinn 1997), and Tse’an Kaetan Cave (Hill et al. 2000). Cave crickets were observed on
the walls and ceilings near the entrances and near the back areas of Horseshoe Mesa caves (Welbourn
1978). Welbourn (1978) suggested that these crickets leave the caves at night to feed, and observed
crickets on the walls outside the entrance of Cave of the Domes. Hill et al. (1998) suggested that their
cricket observations in Cave of the Domes are C. yavapai. Drost and Blinn (1997) documented a Ceu-
thophilus sp. at the entrance of Roaring Springs.
242 Wynne, Drost, Cobb, and Rihs
Order Plecoptera
Family Perlidae
Hesperoperla pacifica Banks 1900. Troglophile. Roaring Springs Cave (Drost and Blinn 1997). Numerous
aquatic nymphs and some flying adults were observed from near the entrance through the dark zone.
Order Psocoptera
Family Psocidae
Psyllipsocus ramburii Selys-Longchamps 1872. Troglophile (Peck 1980). Tapeats Cave (Peck 1980), Bat
Cave (Pape 1998), Babylon Cave, Cave of the Domes, Tse An Cho Cave, and Tuning Fork Cave (Wel-
bourn 1976). Peck (1980) collected one specimen from a “decayed leaf on moist rock floor in dark
zone,” but indicated that this species was frequently observed within dry detritus. Pape (1998) sug-
gested that this invertebrate feeds on micro-fungi occurring on guano deposits; Pape also suggested
that the psocids observed within Bat Cave were likely the same species collected and identified by Peck
(1980) at Tapeats Cave. Welbourn (1978) identified psocids (likely P. ramburii) in organic material and
guano within the dark zones of these Horseshoe Mesa caves.
Order Coleoptera
Family Carabidae
Bembidion sp. Unknown cavernicole. Roaring Springs Cave (Drost and Blinn 1997). Drost and Blinn
observed this species within the cave entrance.
Family Leiodidae
Ptomaphagus cocytus Peck 1973. Troglobite (Peck 1980). Guanophile? Roaring Springs Cave (Peck 1980;
Drost and Blinn 1997) and Tapeats Cave (Peck 1980). In Roaring Springs Cave, adults and larvae were
observed “feeding on a few scattered mouse (or bat?) droppings on moist sand,” while in Tapeats Cave
they were on “droppings and decaying cottonwood leaves on moist floor” in the cave’s dark zone
(Peck 1980).
Family Tenebrionidae
Eschatomoxys sp. Troglophile (Peck 1980). Thunder River Cave (Peck 1980) and Bat Cave (Pape 1998).
Peck (1980) collected one specimen within a dry passage of Thunder River Cave. Pape (1998) suggested
that the tenebrionid beetle observed within Bat Cave is likely the same species collected and identified
from Thunder River Cave.
Eleodes (Caverneleodes) leptoselis Triplehorn 1975. Troglophile? (Welbourn 1978; unknown cavernicole).
Cave of the Domes (Triplehorn 1975; Welbourn 1978; Hill et al. 1998), Cave 68-Olie (Triplehorn 1975),
Tse An Cho Cave (Triplehorn 1975; Welbourn 1978), and Land’s End Cave, Scorpion Cave, and Tuning
Fork Cave (Welbourn 1978). Welbourn observed these beetles on the cave floor and walls within the
dark zone, and indicated that they were commonly found in Cave of the Domes. Hill et al. (1998)
observed three dead tenebrionid beetles within the entrance area and near the cave register at Cave of
the Domes, and suggests that this was likely E. leptoselis.
Family Curculionidae
Smicronyx imbricatus Casey 1892. Special case. Bat Cave (Pape 1998). Pape suggested that larvae of this
species were brought into the cave and deposited in the seeds contained within Bassariscus astutus
(ringtail cat) scat.
Order Hymenoptera
Family Sphecidae
Sceliphron sp. or Chalybion sp. Trogloxene (Pape 1998). Bat Cave (Pape 1998). Pape indicated that “the
only use of the cave by this species is for shelter for nest building and its relationship is that of a
trogloxene.”
Order Trichoptera
Family Brachycentridae
Micrasema onisca Ross 1947. Troglophile. Roaring Springs Cave (Drost and Blinn 1997). Drost and Blinn
recorded an adult within the twilight zone of the cave. M. onisca had not previously been recorded in
Arizona.
Wynne, Drost, Cobb, and Rihs 243
Family Lepidostomatidae
Lepidostoma apornum Denning 1949. Troglophile. Roaring Springs Cave (Drost and Blinn 1997). Drost
and Blinn collected an adult of this species within the twilight zone of the cave, which was a first
record in Arizona.
Order Lepidoptera
Family Tineidae
Tinea nov. sp. Troglophile (Pape 1998). Bat Cave (Pape 1998) and Crystal Forest Cave (Welbourn 1978).
At least two species of tineids were identified within Bat Cave, with one representing a new species
(Pape 1998). During the larval stage, they feed on fresh guano (Pape 1998). An unidentified tineid was
observed on a wall near the entrance of Crystal Forest Cave (Welbourn 1978).
Family Noctuidae
Pronoctua typica Smith 1894. Trogloxene (Peck 1980). Roaring Springs Cave (Peck 1980; Drost and Blinn
1997). Peck (1980) noted adult moths “on the ceiling and walls … just inside the dark zone.” This is a
wide-ranging species in the West occurring from British Columbia to California and Arizona (Peck
1980). Peck indicated that other members belonging to the subfamily Noctuinae are known to hiber-
nate or aestivate in caves.
Family Arctiidae?
Undetermined genus and species. Troglophile. Tse’an Kaetan Cave (Hill et al. 2000). Hill et al. docu-
mented casings of pupal moths.
Order Siphonaptera
Family Ichnopsyllidae
Sternopsylla texana Fox 1914. Special case: ectoparasite. Bat Cave (Pape 1998). This species is believed to
be present while Mexican free-tailed bats (Tadarida brasiliensis) are in residence (Pape 1998).
Order Diptera
Family Tipulidae
Undetermined genus and species. Trogloxene (Welbourn 1978). Cave of the Domes (Welbourn 1978).
One specimen was collected from the cave entrance room wall.
Limonia sp. Unknown cavernicole. Roaring Springs Cave (Drost and Blinn 1997). This species was iden-
tified within the twilight zone.
Tipula (Bellardina) rupicola Doane 1912. Trogloxene (Peck 1980). Roaring Springs Cave (Peck 1980; Drost
and Blinn 1997). This species was noted in the twilight zone of the cave (Peck 1980; Drost and Blinn
1997). Peck (1980) suggested that this species used the cave as a “daytime retreat.”
Family Mycetophilidae
Mycetophila sp. Trogloxene (Peck 1980). Roaring Springs Cave (Peck 1980; Drost and Blinn 1997). This
species was identified within the twilight zone (Drost and Blinn 1997), and also in the dark zone (Peck
1980). Mycetophila occurs widely in western North America, and has been recorded in other caves (Peck
1980).
Family Sciaridae
Sciara sp. Undetermined species. Troglophile (Peck 1980). Tapeats Cave (Peck 1980). Peck identified
one adult on rotting leaves in the cave’s dark zone. Fungus gnats of this genus are often found in asso-
ciation with wet caves (Peck 1980).
244 Wynne, Drost, Cobb, and Rihs
Figure 1.
Stygobromus
blinni
Wang and Holsinger 2001. This endemic stygobite was found in the
middle and deep zone of Roaring Springs Cave. It is currently known only from Roaring Springs
Cave and its associated waters. Photo courtesy D. Blinn.
DISCUSSION
This review underscores the need for addi-
tional research on cavernicole invertebrates
in the Grand Canyon. Of the 15 caves re-
ported, endemic troglomorphic species have
been confirmed from only two caves—Roar-
ing Springs and Tapeats. Additionally, four
species may prove to be endemic to Grand
Canyon caves, but this awaits further study.
Peck (1978) has suggested that the low
numbers of cave-adapted taxa in the U.S.
Southwest are due to low nutrient input and
the high cryptoaridity associated with
Southwest cave systems, but it is evident
that the low numbers from Grand Canyon
caves also reflect limited sampling efforts.
Although voucher specimens were used
to identify 30 of 37 (~81%) invertebrates
presented in this review, most research
undertaken in Grand Canyon caves has
employed visual observation to identify
invertebrates. As indicated by Barr and
Reddell (1967), cave inventories cannot be
considered complete without invertebrate
trapping. Grand Canyon species lists for
each cave should therefore be considered
incomplete. Species identifications made
from visual surveys are open to question
due to the difficulty in identifying most
invertebrate species; they do not provide a
strong basis for comparative studies, and are
of limited value. We also recognize that
taxonomic expertise among the authors
likely differs, so it is possible that some
species have been previously recorded
under multiple names, and some may have
been incorrectly identified.
Wynne, Drost, Cobb, and Rihs 245
To best further the knowledge of Grand
Canyon cave entomology and allow for
comparative analyses, we propose the use of
a standardized systematic approach. We
propose an inventory protocol for sampling
invertebrates that employs both a random
sampling strategy with specimen collection
and a suite of the most effective currently
known techniques. Sampling field sessions
should last at least 14 days and should take
place during at least two seasons (e.g., 7
days during summer and 7 during winter),
and representative sampling should be done
within the three light zones (light, twilight,
and dark). Because baited traps are general-
ly more effective than unbaited traps, and
result in higher capture rates (Slaney and
Weinstein 1996), we recommend using
baited pitfall and leaf litter trapping tech-
niques. Direct intuitive searches should also
be conducted because many predacious and
winged invertebrates are not likely to be
captured using baited trapping techniques.
Searches should occur in areas deemed most
likely to contain certain invertebrate species.
To reduce the risk of overcollecting, only
three to five individuals per species should
be collected, which is considered adequate
for positive identification (Schneider and
Culver 2004).
The information presented here repre-
sents about 5 percent of the caves known to
occur in Grand Canyon National Park (Tom
Gilliland, Arizona Cave Survey, personal
communication 2006). Thus, by implement-
ing an inventory program with a consistent
and rigorous sampling design with judicious
specimen collection, using the protocols
outlined above, researchers will obtain more
reliable estimates of species richness (on a
per-cave basis), yielding a stronger basis for
conducting comparative analyses across
cave systems and likely leading to the iden-
tification of more endemic and troglomor-
phic invertebrates in Grand Canyon caves.
CONCLUSION
Caves are among the most fragile and un-
derstudied ecosystems on Earth. Limited
research exists on caves in Grand Canyon
National Park and the southern Colorado
Plateau. We reviewed all available literature,
including cave trip reports, comprising just
nine studies of 15 caves at Grand Canyon
National Park. Approximately 37 cave-
dwelling invertebrates are known to occur
in Grand Canyon caves (3 troglobites, 6
trogloxenes, 14 troglophiles, 1 stygobite, 10
unknown cavernicoles, and 3 special case
species). Currently, only four cave-adapted
taxa are known for the Grand Canyon.
Because there are published data for only
about 5 percent of the known caves in Grand
Canyon National Park, more endemic cave-
adapted invertebrates are expected to be
found in the future.
ACKNOWLEDGMENTS
The staff of the Grand Canyon National Park
Museum Collections was most helpful in
locating information on cave invertebrates in
their holdings. T. Gilleland provided valu-
able insights into the general level of cave
study in the Grand Canyon region. S. B.
Peck provided additional information on his
stream cave survey. E. Bernard provided
insights regarding current Collembola
taxonomy. D. Blinn provided the photo of
Stygobromus blinni. We extend much grati-
tude to three anonymous reviewers whose
comments greatly improved the manuscript.
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