Anobiidae - Niptus ventriculus
Size: 3.00 mm
Group Guild Status
Troglophile Scavenger Uncommon
These animals are called spider beetles due to the rounded body and spider-like general appearance of some species, and are included in their own subfamily, the Ptininae. Species of spider beetles are fairly common in drier parts of cave entrance areas in the southwest (RBP, personal observation); They are probably scavengers, and are commonly found in association with wood rat (Neotoma spp.) middens, where they may feed on feces, mold, or organic nest materials. Endemic cave species of Niptus, which have reduced eyes, are recorded from a few caves in California and Utah (Aalbu and Andrews 2005).
N. ventriculus is known from two observations of the species in the Crinoid Room, one of which was taken from the web (as prey) of a female Achaearanea canionis. The species is reported from wood rat middens in north central Baja California near Cataviña (Clark and Sankey 1999), and in the Puerto Blanco Mountains in southwestern Arizona (Hall et al. 1990). The specimens from Kartchner Caverns show no obvious morphological adaptations for a subterranean existence.
Even though only two individuals of this species were encountered during the recent study, we do not consider it rare, but likely uncommon in the cave. N. ventriculus will normally occur only in the drier portions of the cave near entrances, and possibly only where there is an association with rodents.
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