Crossidius suturalis pubescens

Distinguished from other Crossidius species by combination of host plant association with Isocoma tenuisecta, orange-reddish coloration with black elytral markings, and male antennae longer than female antennae. Differentiation from subspecies C. s. intermedius and C. s. suturalis requires examination of subtle morphological characters, including degree of pubescence and specific elytral marking patterns. Has been confused with C. hurdi in the field due to variable maculation patterns; specimens from the type locality area near Rodeo, New Mexico, initially appeared intermediate between the two species but were subsequently determined to represent C. suturalis.

Adults are medium-sized cerambycid beetles with elongated bodies. As a subspecies of C. suturalis, individuals exhibit the characteristic orange to reddish-orange coloration with black elytral markings typical of the species complex. Males possess notably longer antennae than females. The subspecific epithet "pubescens" suggests a relatively hairy or pubescent body surface compared to other subspecies, though specific diagnostic features distinguishing this subspecies from C. s. intermedius and C. s. suturalis require detailed examination.

Arid and semi-arid regions of the southwestern United States, specifically in desert grassland and Chihuahuan Desert scrub habitats. Associated with roadside stands and natural populations of its host plant Isocoma tenuisecta (burroweed). Occurs in areas with sandy to rocky soils where this composite shrub grows, often in disturbed habitats such as roadsides and dry washes. Elevation range includes lowland desert areas to moderate elevations in associated mountain foothills.

Southwestern United States: documented from southeastern Arizona (Cochise, Graham, Pima, and Santa Cruz counties) and southwestern New Mexico (Hidalgo County, including type locality near Rodeo). The subspecies occurs in the transition zone between the Sonoran and Chihuahuan deserts. Distribution records from GBIF indicate presence in Mexico (MX) and United States (US), though specific Mexican localities are not detailed in available sources.

Adult activity observed from early September through at least mid-September, with peak activity coinciding with flowering of Isocoma tenuisecta. Field observations from 2019 indicate emergence may be triggered by monsoon season rains, with beetles appearing on host plants as flowers begin to open. Timing appears slightly earlier than related species such as C. coralinus in more western populations. Activity is diurnal, with adults visible on flowers during daylight hours.

• Isocoma tenuisecta - adult feeding/oviposition sitePrimary host plant; adults found on flowers and pre-blooming plants. A composite (Asteraceae) shrub known as burroweed or rayless goldenrod.
• Gutierrezia microcephala - adult occurrenceOccasionally found on this composite; may represent incidental occurrence or secondary host use.

Adults are flower visitors, actively seeking composite flowers for feeding and presumably mating. Observed perching on host plant stems and flowers, with mating pairs documented on Isocoma tenuisecta inflorescences. When disturbed, adults may take flight with a characteristic spiraling flight pattern. Activity appears tied to host plant phenology, with adults emerging and becoming active as Isocoma tenuisecta enters bloom. Males use their elongated antennae to detect females, as evidenced by mating pair observations showing pronounced antennal length dimorphism.

Adults function as pollinators of their host plants while feeding on floral resources. As herbivores, larvae likely develop in roots or stems of host plants, though this has not been directly documented for this subspecies. Contributes to local biodiversity as a specialist herbivore in desert ecosystems and serves as prey for generalist predators including spiders and insectivorous birds.

Subject of scientific collecting for taxonomic and molecular studies, with specimens collected for future DNA analysis to clarify relationships among subspecific taxa within C. suturalis. Of interest to cerambycid specialists due to taxonomic complexity and variation within the species. No known economic importance; not a pest of agriculture or forestry.

• Crossidius hurdiOverlaps in distribution and host plant use; variable maculation in C. suturalis pubescens has caused field confusion, requiring specimen examination for reliable separation.
• Crossidius pulchellusSympatric in Arizona and New Mexico; distinguished by smaller size, different elytral pattern, and primary association with Gutierrezia rather than Isocoma.
• Crossidius suturalis intermediusAnother subspecies of C. suturalis; intermedius occurs in different geographic areas with some range overlap, requiring detailed morphological comparison for identification.
• Crossidius coralinusSimilar orange-and-black coloration and flower-visiting behavior; distinguished by association with Ericameria nauseosa in more western habitats and different elytral marking patterns.

• Cerambycidae
• longhorn beetle
• flower beetle
• desert insect
• Arizona
• New Mexico
• Isocoma
• Trachyderini
• subspecies

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• Catalogue of Life
• Halictidae | Beetles In The Bush