Formicidae - Neivamyrmex graciellae
Size: 4.17 mm
Group Guild Status
Subtgroglophile Predator Uncommon
Ants were not actually observed during the initial study, but their presence was inferred from what appeared to be old ant trails in the soil floor of the cave just outside and just inside of the entrance to the Red River Passage. These old trails are still visible today (Photo 1). During the recent study we found what are obviously more recent ant trails in the Red River Passage (Photo 2) and, ultimately observed this army ant species using the trails. The trails are identical to those constructed by army ants elsewhere, both on forest floors in the tropics (Figure 5.9 in Schneirla, 1971; Plate 12 in Gotwald, 1995), and in caves (Figure 8 in Reddell and Cokendolpher 2001; trail of Labidus coecus). The trails are constructed by removing vegetation and litter from the ground surface (epigean environments), and piling soil particles at the sides, resulting in an uncluttered trench (in both epigean and hypogean environments).
During the recent study, we observed N. graciellae (Photo 3) active in the cave only once (in June of 2011), when we encountered a sparse column of them running along a trail near the junction of Main Corridor and the Anticipation Room. Approximately a dozen ants could be seen at any given time along this stretch.
Species of Neivamyrmex have been recorded previously from caves only incidentally, from Texas and Mexico, and the ants in these occurrences were considered accidentals (Reddell and Cokendolpher 2001). However, two species of Neivamyrmex were previously observed in Arkenstone Cave (RBP, personal observation), and Neivamyrmex is now also known from Kartchner Caverns (also two, but different species). These records from two Arizona caves are the only non-accidental cave occurrences documented for Neivamyrmex spp. The presence of Neivamyrmex spp. in caves in the southwest is probably more common than has been documented. There are no confirmed troglobitic ant species (Holldobler and Wilson 1990; Decu et al. 1998).
There have been occasional sightings of ants in the cave by KCSP staff, and they are probably usually N. graciellae. It appears that this species is more common in the cave than the other recorded army ant (N. leonardi), which has been found in the cave only once. This is based primarily on the assumption that the army ant trails that have been observed in the Red River Passage area all belong to N. graciellae. We infer this from the large size, both in depth and width of the trails, which would appear to not be a match with the smaller, more “delicate” N. leonardi. Another New World army ant species L. coecus is fairly common in caves in Texas and Mexico, where they make very prominent entrenched trails (Reddell and Cokendolpher 2001). L. coecus has so far not been recorded from Arizona.
See Pape (2016) under the Publications tab for updated information on this species.
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