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Subspecies Trimerotropis agrestis barnumi
Classification Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Orthoptera (Grasshoppers, Crickets, Katydids)
Suborder Caelifera (Grasshoppers)
Family Acrididae (Short-horned Grasshoppers)
Subfamily Oedipodinae (Band-winged Grasshoppers)
Tribe Trimerotropini
Genus Trimerotropis
Species agrestis (Toothed Dune Grasshopper)
Subspecies barnumi (Trimerotropis agrestis barnumi)
Synonyms and other taxonomic changes Trimerotropis agrestis barnumi Tinkham, 1960, from Oak City Dunes, Millard County, Utah
Trimerotropis agrestis gracewileyae, Tinkham, 1961, from Cane Springs Dunes, Emery County, Utah
Trimerotropis agrestis hewitti Tinkham, 1964, from ne. of Bruneau, Owyhee County, Idaho
Explanation of Names This subspecies, from west of the Great Plains, was described as Trimerotropis agrestis subspecies barnumi by Tinkham in 1960, with other names [gracewileyae and hewitti] given to basically the same thing from different locations. There is a tendency for the insects in each isolated area of dunes to look a little different, and this is why Tinkham gave three names (more could easily be given, if one were to recognize each different-looking population as a subspecies). Otte treated T. barnumi as a distinct species in 1984, with Tinkham's other names listed as synonyms. There is little difference between "T. barnumi" and "T. agrestis", but they are recognizable, and are here treated as subspecies of one species, as originally described by Tinkham.
It should also be noted that T. agrestis merges with T. maritima on the Great Plains with intermediates occuring wherever the habitats of the two meet. So, while it has never been done, a good case can be made for calling T. agrestis and T. agrestis barnumi subspecies of T. maritima.
Identification A distinctive insect, most likely to be confused with Xanthippus montanus, which usually occurs earlier in the year, is usually a bit larger, and which has the spots on the body and tegmina usually larger and less "speckled" looking than in this one.
Subspecies agrestis occurs further east on the Great Plains, and is a bit plainer looking, less likely to have the pale lines on top, has the sides of the pronotum less expanded, and usually has some black on the inside of the hind femur (plain reddish on barnami). The two subspecies are isolated from one another on opposite sides of the Rockies, except in Wyoming where intermediate looking populations occur. Subspecies agrestis is different only in degrees from subspecies barnumi. The appearance of subspecies agrestis is likely influenced by contact with T. maritima, with which it blends where they meet eastward.
Other plain to speckled species of Trimerotropis found in the same area, and with red hind tibiae, lack the expanded rear lower angles on the pronotum; or, (T. whitei in Arizona) are much smaller in size.
Range Sand areas, mostly on moderately stable dunes in grassland and open woodland, from western New Mexico, Colorado, and Wyoming westward into Idaho northern Arizona, and Nevada. It is found scattered through most of Utah. It may be in southeastern Oregon.
Habitat Sand areas, usually smallish dunes or the margins of large dune fields, associated with colonies of Lemon Scurf Pea or desert Twinbugs (see under "Food" below).
Season Eggs in winter, adults late spring to autumn. Usually Most common in July or August.
Food In most areas perhaps using almost exclusively Psoralea (Psoralidium) lanceolata (family Fabaceae), which seem to almost always be found where these grasshoppers are present.
In hotter parts of the Colorado Plateaus (where the Psoralea is not found), this Grasshopper is often more rare, and seems to be associated then with Desert Twinbugs - Dicoria canescens ssp. brandegeei (family Asteraceae).
Contributed by David J. Ferguson on 10 August, 2008 - 3:07am Last updated 23 March, 2015 - 1:20pm |
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