Scraptiidae - Anaspis nr. rufa - undescribed species
Anaspis nr. rufa - undescribed species
Size: 3.64 mm
Group Guild Status
Eutroglophile Unknown Uncommon
This small (3.5 to 4.0 mm in length) beetle initially proved to be quite enigmatic. Prior to and through the recent study the beetles were known only from five recorded occurrences (consisting of 8 individuals; all apparently females) that were sampled between 2005 and 2011; all of which were found drowned in the environmental monitoring station evaporation pan at Grand Central Station. Most of the specimens retrieved from the evaporation pan were in poor condition, some consisting of merely an aggregation of disarticulated parts. Fortunately, one of the specimens was complete enough to permit identification.
Species in the family (Scraptiidae) are typically associated with flowers or occur beneath bark of trees (Triplehorn and Johnson 2004). However, A. rufa is reported to be mycetophagous (fungivorous) (Majka 2010). The species was reported from late Quaternary wood rat (packrat) middens at Bida Cave in northern Arizona, south of the confluence of the Colorado and Little Colorado rivers. Its presence in wood rat middens was interpreted as a potential commensal association, with the beetles likely feeding on wood rat nest materials or the midden waste pile. The age of the sample was dated between 28 and 21 kya (Elias et al. 1992). The fungivorous habit of the species ties in nicely with its presence in mammal nests, and we suspect that the beetles are commensally associated with wood rats that live in the collapsed Entrance Sink at Kartchner Caverns. In this situation the beetles (particularly the larvae) may feed on molds associated with vegetation elements of the wood rat nests and/or on wood rat fecal material. Long-term commensal associations of these beetles with wood rats in cave entrance areas could conceivably eventually result in evolution of eutroglophilic populations.
Only a single live animal has been found in the cave to date, beneath a rock in the Crinoid Room. The Crinoid Room is the first room in the cave inside the collapsed Entrance Sink. Wood rats (Neotoma sp.) are established in the Entrance Sink area, and finding a live beetle in this area supports the proposed wood rat nest association for the species. Assuming the beetles are ecologically linked with the wood rats, it seems odd that they would penetrate as deep into the cave as Grand Central Station (approximately 60 meters distant) where there is no wood rat activity. Obviously they are attracted (fatally it turns out) to the water at the EMS station, but this seems counter-intuitive for a species adapted to a dry habitat such as wood rat middens. There are numerous EMS stations throughout the cave, and the species has so far been found only at the Grand Central Station EMS site. However, the Grand Central EMS site is the closest one to the Entrance Sink area where the single live animal was found.
Based on our limited data set the species seems to have a long-term presence in the cave (records spanning an eight year period), appears to be localized in the cave, and we therefore consider it a regular element of the cave fauna. We suspect the animal is a eutroglophile. We believe that the population represents an undescribed species.
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