Ironclad ID: Tool for Diagnosing Ironclad and Cylindrical Bark Beetles (Coleoptera: Zopheridae) of North America north of Mexico
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Genus: Zopherus

Diagnostic Features
  • Description: Antennae 9-segmented with a 1-segmented club composed of 3 fused segments. Antennal setation sparse. Eyes well-developed, elongate-oval, somewhat reniform, coarsely faceted, extending well onto dorsal portion of head. Males without setose pit on submentum. Lateral margins of pronotum arcuate to sinuate, without distinct lobes, narrowed posteriorly. Hypomeron with deep antennal cavities. Prosternum with or without distinct transverse groove. Procoxal cavities closed. Metacoxae moderately separated, separation slightly narrower than metacoxal length. Scutellum small, visible to indistinct. Abdominal ventrite 5 with an undivided preapical groove. Femora and tibia with paired rows of golden setae on inner face. Tarsal formula 5-5-4. Dorsal surface glabrous, piceus to bicolored with white and black.
  • Similar genera: The genus Zopherus is similar to the genera Sesaspis, Phloeodes, and Phellopsis, but can immediately be distinguished by the 9-segmented antennae with a 1-segmented club composed of 3 fused segments, the deep antennal cavities on the prothoracic hypomera, and the paired rows of fine golden setae on all femora and tibiae.
Known Distribution
  • Southwest (AZ, CA, CO, NM, NV, UT), Southcentral (TX) USA; Mexico.
Biology
  • Zopherus occurs in rotting wood and plant matter. It is speculated that some members may be morphologically adapted (as larvae) for boring into sound wood (Doyen and Lawrence, 1979; Ślipiński and Lawrence, 1999). Larvae of Zopherus nodulosus has been found in pecan timber (Carya sp.) and larvae of Z. granicollis have been collected from the root crown of Pinus monophylla (Doyen and Lawrence, 1979).

  • Abundance: Some species are locally common.
North American Species (11)

Zopherus championi Triplehorn, 1972
Zopherus championi Triplehorn, 1972 [black]
Zopherus concolor LeConte, 1851
Zopherus elegans Horn, 1870
Zopherus elegans Horn, 1870 [black]
Zopherus gracilis Horn, 1867
Zopherus granicollis Horn, 1885
Zopherus nodulosus nodulosus Solier, 1841
Zopherus nodulosus nodulosus Solier, 1841 [black]
Zopherus nodulosus haldemani Horn, 1870
Zopherus opacus Horn, 1867
Zopherus sanctaehelenae (Blaisdell, 1931)
Zopherus tristis LeConte, 1851
Zopherus uteanus (Casey), 1907
Zopherus xestus Triplehorn, 1972

Species Diagnoses
  • Zopherus championi: This species can be readily distinguished by the elytral apex bearing 2 swollen, oblique ridges on each side and the lateral margins of the elytra and pronotum bordered in white (some specimens lack white lateral margins). This species is most similar to Z. elegans, and can be distinguished by pronotal surface consisting of simple punctures (compared to small, scabrous bumps or tubercles in Z. elegans) and the prosternum anterad of procoxae with punctured but lacking distinct tubercles. This species may sometimes be covered in a greasy exudate, rendering the specimen almost entirely black in color. If this is the case, Z. championi will greatly resemble Z. gracilis, but can be separated by the distribution, more convex pronotal disc, punctures on pronotal disc deeper, and a hint of coloration on the elytra. Distribution: Texas, USA; Mexico.

  • Zopherus concolor: This species can be readily distinguished by the elytral apex bearing 2 swollen, oblique ridges on each side, solid black body, pronotum with small, deep, moderately sparse punctures, and distinctly scabrous, irregularly tuberculate elytral sculpture (as opposed to vermiculate in other species). Z. concolor is most similar to Z. tristis, but can be distinguished by the shallower and more sparse pronotal punctures and the elytral scabrous tublercles more distinctly raised and prominent. Distribution: New Mexico, Texas, USA.

  • Zopherus elegans: This species can be readily distinguished by the elytral apex bearing 2 swollen, oblique ridges on each side and the lateral margins of the elytra and pronotum bordered in white (some specimens lack white lateral margins). This species is most similar to Z. championi, and can be distinguished by pronotal surface consisting of small, scabrous bumps or tubercles (compared to simple punctures in Z. championi) and the prosternum anterad of procoxae with distinct tubercles, not punctures. This species may sometimes lack the whitish lateral pronotal and elytral margins, rendering the specimen almost entirely black in color. If this is the case, Z. elegans will greatly resemble Z. granicollis and Z. uteanus, but can be separated by the evenly curved anterior margin of the pronoum (when viewed anteriorly), as opposed to bisinuate in Z. granicollis and Z. uteanus. Distribution: Arizona, New Mexico, Utah, USA.

  • Zopherus gracilis: This species can be readily distinguished by the elytral apex bearing 2 swollen, oblique ridges on each side and the pronotum smooth, impunctate, the elytra impunctate, smooth to slightly wrinkled, and the solid black dorsum. Z. gracilis is most similar to Z. gracilis but can immediately be distinguished by the 2 slightly swollen oblique ridges at the elytral apex, whereas in Z. xestus the elytral apex bears 2 large, swollen, oval tubercles. Distribution: Arizona, New Mexico, USA; Mexico.

  • Zopherus granicollis: This species can be readily distinguished by the elytral apex bearing 2 swollen, oblique ridges on each side, solid black body, pronotum and elytra bearing small, regular scabrous tubercles subequal in size and more or less evenly distributed. Z. granicollis is most similar to Z. uteanus, but differs in the prosternal process between the coxae more densely punctate (as opposed to sparsely punctate in Z. uteanus), coarser clypeal punctures, and pronotum usually narrower than elytra. NOTE: This species has two subspecies, Z. granicollis granicollis and Z. granicollis ventriosus. Z. granicollis granicollis can be separated from Z. granicollis ventriosus in the overall larger size of the elytral tubercles and lateral tubercles of the elytra similar in size and shape to those on rest of elytra, whereas in Z. granicollis ventriosus, the elytral tubercles are overall smaller in size and the lateral tubercles of the elytra are transversely elongate. Distribution: Arizona, California, Nevada, USA; Mexico.

  • Zopherus opacus: This species can be readily distinguished by the elytral apex bearing 2 swollen, oblique ridges on each side, solid black body, pronotum with small, moderately dense punctures, and distinctly vermiculate and minutely tuberculate or bumpy elytral sculpture (as opposed to with scabrous, flattened tubercles in other species) The similar size and density of the small bumps/tubercles of the pronotum and elytra serve to separate this species. Distribution: California, Nevada, Utah, USA.

  • Zopherus nodulosus: This species can be readily distinguished by the elytral apex bearing 4 distinct tubercles, the inner pair being smaller than the outer, and the bicolorous, black and white dorsum. NOTE: This species has two subspecies, Z. nodulosus nodulosus and Z. nodulosus haldemani. Z. nodulosus nodulosus can be separated from Z. nodulosus haldemani in the pronotum and elytra mostly white with black coloration mostly restricted to midline, whereas in Z. nodulosus haldemani, the black coloration is more widespread. There can also be darker color morphs (nearly all black) of both subspecies. Z. nodulosus nodulosus occurs in Mexico whereas Z. nodulosus haldemani occurs in Texas and Mexico. Distribution: Texas, USA; Mexico.

  • Zopherus sanctaehelenae: This species can be readily distinguished by the elytral apex bearing 2 swollen, oblique ridges on each side, solid black body, pronotum with small, moderately sparse punctures, and distinctly vermiculate and minutely punctate elytral sculpture (as opposed to with scabrous, flattened tubercles in other species). Distribution: California, USA.

  • Zopherus tristis: This species can be readily distinguished by the elytral apex bearing 2 swollen, oblique ridges on each side, solid black body, pronotum with small, deep, moderately sparse punctures, and distinctly scabrous, irregularly tuberculate elytral sculpture (as opposed to vermiculate in other species). Z. tristis is most similar to Z. concolor, but can be distinguished by the deeper and more dense pronotal punctures and the elytral scabrous tublercles less distinctly raised. Distribution: Arizona, California, Colorado, Texas, USA; Mexico.

  • Zopherus uteanus: This species can be readily distinguished by the elytral apex bearing 2 swollen, oblique ridges on each side, solid black body, pronotum and elytra bearing small, regular scabrous tubercles subequal in size and more or less evenly distributed. Z. uteanus is most similar to Z. granicollis, but differs in the prosternal process between the coxae sparsely punctate (as opposed to more densely punctate in Z. granicollis), clypeal punctures smaller and sparser, and pronotum usually as wide or wider than elytra. Distribution: Arizona, California, Nevada, Utah, USA.

  • Zopherus xestus: This species can be readily distinguished by the elytral apex bearing 2 distinct tubercles, the pronotum smooth, impunctate, the elytra impunctate, smooth to slightly wrinkled, and the solid black dorsum. Z. xestus is most similar to Z. gracilis but can immediately be distinguished by the 2 tubercles at the elytral apex large, swollen, and oval in shape, whereas in Z. gracilis the elytral apex bears a slightly swollen oblique ridge. Distribution: Texas, USA.
Potential Problems with Identification
  • Many of the North American members of this genus are quite similar in general appearance and can be difficult to accurately identify. The species which exhibit patterns of black and white coloration also have black forms, which greatly hinder identification. This black coloration is caused by a greasy exudate, which conceals the white coloration and many of the surface sculpture. The exudate can be removed by soaking the specimen in a grease solvent.
Selected References  

Zopherus championi
© N.P. Lord

© 2011-2015 Lord, N.P., Nearns, E.H., and K.B. Miller
The University of New Mexico and Center for Plant Health Science and Technology, USDA, APHIS, PPQ.