Crossidius humeralis

LeConte, 1858

Species Guides

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Crossidius humeralis is a of longhorn beetle in the Cerambycidae, first described by John Lawrence LeConte in 1858. It belongs to a diverse, exclusively western North American whose members are intimately associated with flowering shrubs in the Asteraceae family. Like other Crossidius species, are and strongly tied to their plants for feeding and .

Crossidius humeralis by (c) Tom Kennedy, some rights reserved (CC BY), uploaded by Tom Kennedy. Used under a CC-BY license.

Pronunciation

How to pronounce Crossidius humeralis: /krɔːˈsɪdiʊs huːˈmɛrælɪs/

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

Identification

The Crossidius can be distinguished from most other cerambycid genera by the combination of: active on flowers of Asteraceae shrubs (Gutierrezia, Chrysothamnus/Ericameria, Haplopappus) rather than woody vegetation; with adults spending their entire brief lives on plant flowers; and larvae that develop in living roots of shrubs rather than dead wood. -level identification within Crossidius requires examination of coloration, elytral maculation patterns, pronotal markings, and antennal proportions, with males typically having longer than females. C. humeralis specifically would require comparison to the 11 described species and numerous , with particular attention to humeral (shoulder) markings suggested by its specific epithet.

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Habitat

include arid and semi-arid regions of western North America where plants in the Asteraceae occur. Specific host plant associations have not been documented for C. humeralis, but utilize Gutierrezia, Chrysothamnus/Ericameria, and Haplopappus .

Distribution

Recorded from Middle America and North America, specifically Mexico (MX) and the United States (US). The precise range within these countries has not been detailed in available sources.

Life Cycle

As with other Crossidius , larvae likely develop as root borers in living, Asteraceae shrubs. emerge to feed on and mate upon the flowers of these plants. The complete duration and number of per year are unknown for this species.

Behavior

are and remain on plant flowers throughout their brief adult lives, even burying themselves among flowers at night rather than leaving the plants. This has been documented for but not specifically observed for C. humeralis.

Similar Taxa

  • Crossidius coralinusShares the same and general ; distinguished by coloration and elytral pattern—C. coralinus typically exhibits bright red and black markings while C. humeralis coloration is undescribed in available sources.
  • Crossidius hirtipesAnother widespread Crossidius with numerous showing extensive polytopism; C. hirtipes subspecies vary from reddish-brown to nearly black and may overlap in distribution with C. humeralis.
  • Other Trachyderini cerambycidsGeneral resemblance in body form and size, but Crossidius are immediately distinguished by their exclusive association with Asteraceae flowers rather than woody .

More Details

Taxonomic note

The authorship year is sometimes cited as 1856 (as in Wikipedia and iNaturalist) but 1858 is the correct date per Catalogue of Life and GBIF, which match the original publication.

Genus characteristics

Crossidius exhibits remarkable polytopism (geographically-based variation) comparable to North American tiger beetles, with 11 described , 36 additional , and numerous locally distinctive . This variability results from discontinuous plant distributions across western topography and hybridization among sympatric species.

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