Calosoma tepidum

LeConte, 1852

lukewarm beautiful black searcher

Calosoma tepidum is a large ground beetle in the Carabidae, Carabinae, first described by LeConte in 1851. It belongs to the 'caterpillar hunter' group within the Calosoma, characterized by large size and predatory habits. The is flightless despite possessing fully developed wings, a condition attributed to thoracic muscle reduction. It has been the subject of recent genomic research as part of a model system for studying wing evolution in insects.

Pronunciation

How to pronounce Calosoma tepidum: /ˌkaləˈsoʊmə ˈtɛpɪdəm/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Habitat

Inhabits areas with open dry ground and sparse low vegetation. In British Columbia, found in forested paths near Blue Lake at 841 m elevation in the South Okanagan Grasslands Protected Area.

Distribution

Western North America. Documented from British Columbia, Arizona, California, Colorado, Idaho, Montana, North Dakota, Nebraska, Nevada, Oregon, Utah, Washington, and Wyoming. Specific collection locality in British Columbia: 49°02′23.4″N 119°33′26.1″W.

Diet

prey on caterpillars and grasshoppers.

Behavior

Active hunter, observed with headlamps at night. Attracted to pitfall traps baited with red wine vinegar. (fully winged) but -unfit due to reduced thoracic flight muscles. When captured live, requires humid conditions (maintained with damp cotton).

Similar Taxa

Calosoma wilkesiiSister from same region (British Columbia), similar and collection locality, both subject of same genomic study. Distinguished by genetic divergence estimated at 25-30 million years and minor chromosomal rearrangements.
Calosoma scrutatorAnother large Calosoma 'caterpillar hunter' with similar arboreal hunting on caterpillars, but distinguished by larger size (25+ mm), more elongated and , and more intense purple coloration on pronotum.
Calosoma wilcoxiSmaller (about one-third the size of C. scrutator) with similar caterpillar-hunting , but C. tepidum is flightless with reduced muscles while C. wilcoxi is capable of flight and known for ascending trees to hunt caterpillars.

More Details

Genomic Resources

- assembly available: 1,243 scaffolds totaling 273 Mb, N50 = 6.5 Mb, 99.3% BUSCO completeness. Annotation includes 21,976 genes with 91.0% BUSCO completeness. Belongs to subgenus Chrysostigma. Used as model for studying genomic basis of wing evolution in insects.

Wing Evolution Significance

Part of emerging model system for studying flightlessness in insects. Despite having fully developed wings (macroptery), the cannot fly due to thoracic muscle reduction—a condition found in about half of Calosoma species, typically associated with of remote including highlands, oceanic islands, and deserts.