Tragidion densiventre

Distinguished from the sympatric T. deceptum by five (vs. four) elytral costae that curve inward toward the suture and extend nearly to the apices, and by a narrower basal black band. Females further distinguished by all black antennae versus the distinctly annulated antennae of T. deceptum females. Males distinguished from T. deceptum males by red-brown (vs. black) head, legs, and scape. Distinguished from T. armatum by ribbed (vs. smooth) elytra.

Medium to large cerambycid beetle with bright aposematic coloration. Males have longer antennae, tawny-tan elytra, and distinctly red-brown head, legs, and scape. Females have shorter antennae and red-orange elytra. Both sexes possess five elytral costae that curve inward toward the suture and extend nearly to the elytral apices. The basal black band on the elytra is relatively narrow compared to related species. Females have all black or nearly black antennae.

Xeric lowland desert habitats in the southwestern United States and northern Mexico. Associated with desert scrub vegetation including mesquite and acacia.

Arizona, New Mexico, and western Texas in the United States; northern Mexico. Predominantly found in lowland desert habitats rather than montane areas.

Adults have been observed in August, with activity likely coinciding with summer monsoon rains. Specific seasonal patterns otherwise undocumented.

• Prosopis glandulosa - larval hostLarvae develop in dead branches
• Acacia greggii - larval hostLarvae develop in dead branches
• Baccharis sarothroides - adult feeding/aggregation siteAdults aggregate on sap oozing from stems

Larvae develop in dead branches of Prosopis glandulosa and Acacia greggii. Detailed life cycle stages otherwise undocumented.

Adults aggregate on sap oozing from stems of Baccharis sarothroides and on flowers of larval host plants. Exhibits Batesian mimicry of tarantula hawk wasps (Pepsis and Hemipepsis). Adults are diurnal and avoid direct sunlight, often lurking on shaded sides of flowers.

Contributes to decomposition of dead woody material in desert ecosystems. Larval boring in dead branches of leguminous trees facilitates nutrient cycling. Adult sap-feeding may aid in wound cleansing of host plants.

Popular among insect collectors due to attractive coloration and mimicry. No documented economic importance. Occasionally encountered by field biologists studying desert ecosystems.

• Tragidion deceptumSympatric and superficially similar with ribbed elytra, but distinguished by four (vs. five) elytral costae, broader basal black band, and different coloration of males (black vs. red-brown head/legs/scape) and female antennae (annulated vs. all black)
• Tragidion armatumSympatric in desert habitats but distinguished by smooth (vs. ribbed) elytra and association with Agave and Yucca (vs. Prosopis and Acacia) as larval hosts
• Tragidion auripenneFormerly considered conspecific; T. densiventre was revalidated from synonymy under T. auripenne; T. auripenne is a rare species known only from the Four Corners region with different host associations

Formerly misidentified as T. annulatum, a name based on an erroneously labeled type specimen that actually refers to populations in California and Baja California. The classic T. 'annulatum' of desert southwest literature and field guides refers to T. densiventre. Also formerly synonymized under T. auripenne.

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• Catalogue of Life
• New species and a review of the genus Tragidion | Beetles In The Bush
• Tragidion confusion | Beetles In The Bush
• new species | Beetles In The Bush
• A review of the genus Tragidion Audinet-Serville, 1834 (Coleoptera: Cerambycidae: Cerambycinae: Trachyderini)