Rhaphidophoridae - Ceuthophilus pima
Size: Approximately 24 mm (not including ovipositor in female); highly variable by age and sex; males commonly smaller
Group Guild Status
Subtroglophile Scavenger Common
This is one of several species of cave (or camel) crickets that inhabit caves in southern Arizona. All known populations documented from caves in Arizona are subtroglophiles. However, there is one species in Arizona (C. baboquivariae), which is apparently “cave” adapted, and is known only from the Baboquivari Mountains (Hubbell 1936). This species may inhabit an unknown cave or caves in the area, and/or may live in deep fractures in the bedrock. According to Hubbell (1936) C. baboquivariae is morphologically relatively equal in the attenuation of its limbs and other features to C. longipes, which is the only known obligatory cavernicolous species (troglobiont) in the genus. C. longipes is known only from Carlsbad Caverns in New Mexico. The initial study mentioned that the Kartchner Caverns population may represent a distinct subspecies (T. Cohn; in Welbourn 1999). The initial study also reported C. pima from another cave in the Whetstone Mountains, and from two caves in the Santa Rita Mountains. Hubbell’s monograph on Ceuthophilus (1936) listed the species as occurring only in the Santa Catalina and Santa Rita Mountains. Specimens in the University of Arizona collection are from these two ranges and the Pinaleño Mountains southwest of Safford, Arizona.
Cave crickets (both Ceuthophilus spp. and Hadenoecus spp.) are important in the delivery of allochthonous nutrient input to many cave environments, and are keystone species in the macro-invertebrate ecology of some caves (Fagan et al. 2007; Hubbell and Norton 1978; Lavoie et al. 2007; Muchmore and Pape 1999). Their fecal material is their primary contribution in these situations, but they are also prey for a variety of predators and their dead bodies recycle nutrients into the caves.
Cave crickets seek shelter in caves from climate extremes, particularly in northern latitudes and at high elevations, where seasonal and nighttime temperatures may be well below temperatures where most invertebrates can function. They use caves for similar reasons in the arid southwest, where low humidity and high summer temperatures create equally unfavorable conditions outside of caves. Some populations have annual cycles, but others breed in caves year-round, as is apparently the case at Kartchner Caverns. This is evident from the presence of all age classes of crickets in the cave year-round. Perennially breeding populations may be correlated with suitable epigean foraging conditions during most of the year, where a nearly continuous availability of nutrients allows for egg production to continue unabated. It seems intuitive that populations at lower elevations may more commonly exhibit this behavior.
Species of Ceuthophilus are rather omnivorous in their diets, feeding primarily on plant materials, but also on fungi, detritus, insects, dead animals, and even engage in cannibalism of injured individuals (Fagan et al. 2007; Lavoie et al. 2007).
Cave populations of Ceuthophilus are apparently sensitive to repeated human intrusion of their habitat, and caves that have high levels of human visitation tend to have fewer cave crickets (RBP personal observation). It is assumed that this relationship is due primarily to loss of suitable egg-laying substrate over time. The loose, silty-clay soils used by Ceuthophilus for oviposition are often heavily impacted by compaction of floor soils from repeated human visitation. This effect is aggravated by a lack of established trails in cave passages, resulting in the entire floor of some passages becoming trampled. Once compacted these soils may never return to conditions suitable for Ceuthophilus (and other arthropod) use. This is just one good reason for establishing trails in newly discovered caves or new areas of known caves as soon as they are found.
Arizona State Parks showed significant foresight in its development of the cave trail system in Kartchner Caverns. The combination of pre-development planning of the trail system layout, low-impact trail design and installation protocols were effective in minimizing resource impacts in the cave. Placement of the utilities beneath the trail system minimized the disturbance footprint in the cave. Curbs designed into the trail structure allow for contained wash-down of the trails into incorporated sumps that collect the gray water, which is returned to the surface where it is dispersed for recharge into the watershed.
The initial study recorded population counts of this species in the area between the historic Entrance Sink and the ingress route junction with Main Corridor of between 300 and 800 individuals at various times during the year. The population was reported as peaking in mid to late summer after the onset of the summer monsoon season. This population fluctuation is similar to that observed for other populations of Ceuthophilus in southern Arizona caves (RBP, personal observation). During the two years of the recent study we found no more than 55 crickets at one time in this same section of the cave. The current population of the crickets in this area of the cave is therefore an order of magnitude lower than the observed pre-development population. Other groupings of these crickets occur at all of the known cave surface connections with the exception of the one in the Tarantula Room.
The large population of C. pima that was present in the cave at the time of the initial study must have been responsible for a significant contribution to the nutrient input to the cave. The drastic reduction in the cave cricket population has no doubt had a negative impact on the macro-invertebrate ecology of the cave. Because cricket guano is derived primarily from plant materials its nutrient content per volume is probably greater than that of bat guano, which contains a high percentage of unusable chitinous remains of insects.
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