Acanthochalcis nigricans
Cameron, 1884
Acanthochalcis nigricans is a large distinguished by on the , which separate it from the similar A. unispinosa. Females possess an exceptionally long and measure approximately 19 mm in total length. The is a known of Chrysobothris , including C. femorata and C. edwardsii, and has been observed seeking sites on dead mesquite branches. It occurs across the southwestern United States from Kansas and Oklahoma west to California.
Pronunciation
How to pronounce Acanthochalcis nigricans: /əˌkænθoʊˈkælˌsɪs ˈnɪɡrɪˌkænz/
These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.
Identification
Separable from Acanthochalcis unispinosa by presence of on (absent in A. unispinosa). The combination of large body size, long , and abdominal pubescent patches is diagnostic. Within , the Acanthochalcis is distinguished by large size and very long ovipositor relative to other chalcidids.
Images
Appearance
Large with greatly swollen and toothed hind characteristic of the . Body predominantly black with distinctive on the . Female with extraordinarily long ; total length including ovipositor approximately 19 mm. Hind femora enlarged and armed with . Distinguished from Acanthochalcis unispinosa by presence of abdominal white pubescent patches (absent in A. unispinosa).
Habitat
Associated with dead wood of mesquite (Prosopis glandulosa) and eastern red-cedar (Juniperus virginiana). Found in arid and semi-arid environments including gypsum-capped mesas, sandhills, and desert scrub. Observed in areas with standing dead mesquite branches showing dieback.
Distribution
Southwestern United States: Kansas, Oklahoma, Texas, New Mexico, Arizona, Nevada, California.
Seasonality
active in summer months. Observed in western Texas in late July. Likely associated with activity periods of Chrysobothris .
Host Associations
- Chrysobothris femorata - Known , Universal Database
- Chrysobothris edwardsii - Known , Universal Database
- Chrysobothris octocola - probable Inferred from field observation on same mesquite branches; not confirmed
- Prosopis glandulosa - Dead branches used for
- Juniperus virginiana - Dead branches used; associations uncertain
Behavior
Females observed actively searching dead mesquite branches, apparently seeking sites. suggests location of within dead wood using long to penetrate wood and on or near host. Has been observed flying around dead mesquite branches and landing on dead wood surfaces.
Ecological Role
of woodboring (), particularly Chrysobothris . Contributes to of these woodboring in arid . Links dead wood to higher .
Human Relevance
Of interest to studying - relationships and . Potential agent for pest Chrysobothris , though not documented as commercially used.
Similar Taxa
- Acanthochalcis unispinosaLacks on ; otherwise similar in size and . Ranges from Texas to California, overlapping with A. nigricans in much of its range.
- Other ChalcididaeDistinguished by large size and exceptionally long ; most chalcidids are smaller with shorter ovipositors.
More Details
Field encounter notes
First individual encountered was the first observed at Gloss Mountains State Park, Oklahoma, on the first day of a trip. Was originally seen on dead mesquite branch, then photographed on eastern red-cedar. All observed that day were associated with dead mesquite branches, suggesting strong fidelity to this substrate.
Taxonomic history
Described by Cameron in 1884. One of only two commonly encountered Acanthochalcis in North America. characterized by large size and very long among chalcidids.