Ptilothrix chiricahua

Distinguished from other Ptilothrix species by the smooth, sparsely punctured ocellocular region (the bare patch between eyes and ocelli appears heavily punctured in similar species). Smaller than European honeybee workers. The combination of rust-colored thoracic hair, yellowish-white abdominal striping on T1–T4, and black hairs on T3–T5 is diagnostic within its range.

Small to medium-sized bee, 8–11 mm in length. Head has striking marbled steel gray-blue eyes with shiny black bald patches (ocellocular region) on top; this bare region is notably smoother than in congeners, with only a few punctures near the eye margin. Legs, head, and thorax bear yellowish to white appressed hairs. Metasomal segments T1–T4 have yellowish to white appressed hairs forming a stripe at the apical end of each segment; T3–T5 have short black hairs. Thoracic dorsum typically has rust-colored hair in most individuals.

Mixed desert grasslands in the Chihuahuan Desert, specifically in areas where the host plant Kallstroemia grandiflora occurs.

Endemic to the Chihuahuan Desert region: southern New Mexico, southern Arizona, western Texas, and northern Mexico including Sonora.

Adults active late summer through fall, coinciding with the bloom period of Kallstroemia grandiflora.

Adults collect pollen and nectar; appears to be an oligolectic specialist on Kallstroemia grandiflora, though occasional visits to introduced cotton (Gossypium) have been reported.

• Kallstroemia grandiflora - primary pollen/nectar sourceLikely oligolectic specialist; flight time synchronized to host bloom
• Gossypium - occasional pollen/nectar sourceintroduced cotton; secondary host

Solitary ground-nesting bee. Nests excavated in soil, with females using water-walking behavior to retrieve water for softening ground during nest construction. Specific details of brood cell provisioning and larval development not documented.

Exhibits water-walking behavior using surface tension to travel across water surfaces and retrieve water for nest excavation. Females are solitary and ground-nesting.

Specialist pollinator of Kallstroemia grandiflora in Chihuahuan Desert ecosystems. Contributes to pollen transfer and reproductive success of this host plant.

Potential indicator species for Chihuahuan Desert ecosystem health. No documented economic importance or pest status. Named in honor of the Chiricahua Apache people, whose historical homeland encompasses the species' range.

• Ptilothrix sumichrastiPreviously considered conspecific; now restricted to southern Mexico and Guatemala. Distinguished by more heavily punctured ocellocular region.
• Ptilothrix zacatecaAnother species split from former P. sumichrasti; geographic separation and subtle morphological differences in head punctation.

• solitary bee
• ground-nesting
• water-walking
• oligolectic
• desert specialist
• Chihuahuan Desert
• pollinator

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• Will climate change be a threat for a new tarantula species?
• Bug Eric: December 2010
• 2018 Arizona Insect Collecting Trip “iReport” | Beetles In The Bush