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Eleodes

This article is about the genus of beetles. For the volcanic range on the Sonora-Arizona border, see Pinacate, California. For the California town, see Pinacate Peaks.

Eleodes (commonly known as pinacate beetles or desert stink beetles) is a genus of darkling beetles, in the family Tenebrionidae.[1] They are endemic to western North America ranging from southern Canada to central Mexico with many species found along the Mexico-United States border.[2] Some species have been introduced to Colombia. The name pinacate is Mexican Spanish, derived from the Nahuatl (Aztec) name for the insect, pinacatl, which translates as "black beetle".[3]

Desert stink beetle
Temporal range: Middle Miocene–Present
Eleodes armata
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Tenebrionidae
Tribe: Amphidorini
Genus: Eleodes
Eschscholtz, 1829
Type species
Eleodes dentipes
Subgenera

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The range of Eleodes

Eleodes species range from about 10 to 50 millimetres (0.39 to 1.97 in) in length[2] and are black in color with some having a reddish tint on their abdomen. The setae of some species such as Eleodes osculans collect debris and give the insect a brown color, a similar effect occurs in the species Eleodes mirabilis giving it the appearance of having whitish stripes on its abdomen.[4] Due to the number of species and their large range these beetles have a fairly varied appearance throughout the many species. All produce quinone or similar substances as a deterrent to predators, and many will stand on their heads to spray it.[5][6] They are typically found in the arid desert regions of their range but can also be found in forests and grasslands. All Eleodes species are flightless as their elytra are fused together and their second pair of wings is very reduced and vestigial.[6][7]

Ecology

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Most members of the genus Eleodes are primarily detrivores feeding on plant and animal debris,[8] some species are more inclined to consume living plants which is especially true for species native to the plains of North America such as Eleodes hispilabris and Eleodes opaca. The larvae of those species and others are considered pests as they feed on the roots of crops.[2]

Species found in dry regions such as members of the subgenus Eleodes are usually much larger than what is expected for most insects, this is due the lack of water in the area leading to these beetles evolving larger bodies in order to hold more of it. Water loss is also the reason that the elytra are fused in Eleodes.[9] As expected, species found in forests, such as members of the subgenus Blapylis are smaller, closer to the size of most other insects.

Eleodes are generally more active at night, some species are strictly nocturnal while others can and will be active during the day. As these beetles are fairly long lived when it comes to insects they must adapt to the different seasons. During the fall they are diurnal as it is warmest during the day. When winter comes they take shelter and become inactive as to not freeze in the cold. When spring arrives they go back to being active in the day until the summer when they switch to being active at night to survive the deadly high temperatures of the desert.[10] Eleodes take shelter almost anywhere that can protect them from the hot and cold, this can be wood or rocks but is often rodent burrows. Every night when these beetles scavenge for food they pick a new shelter for the day which if not suitable for protection against the elements, will be abandoned in search of a new one.[10] One subgenus, Caverneleodes, lives exclusively in caves, cave-like environments, or rock crevices, these beetles have reduced eyes and only leave their hideouts to scavenge for food.[11]

Chemical defense

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Beetles within Eleodes and other genera within Tenebrionidae exude a foul smelling odor and a very distasteful liquid from glands to ward off predators.[6] This liquid is most commonly a form of quinone.[5] While not being poisonous the liquid does usually deter predators, the success of this defense mechanism has led to the evolution of a Müllerian mimicry complex among Eleodes acuticauda, Eleodes dentipes, and Coelocnemis magna, the latter of which while not being within Eleodes is a still distasteful prey item. All three previously mentioned species look strikingly similar leading to a strengthened defense against potential predators. Another Müllerian mimicry complex exists between Eleodes scabrosa and Eleodes tuberculata.[12] The "head-standing" behavior exhibited by these beetles is aposematic.[8] By leaving their presence and identity unambiguous to potential predators, it means that more individuals can survive as predators will avoid beetles with the "head-standing" behavior.

While this defense is generally effective in deterring predators, they are still preyed upon by many species, such as owls, foxes, coyotes, skunks, bats, turtles, etc.[12]

Fossil record and evolution

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Fossils of Eleodes acuticauda, Eleodes osculans, Eleodes carbonaria, Eleodes granulata, Eleodes gracilis, and others have been found in the La Brea Tar Pits, Carpinteria Tar Pits, and the Snowmastodon Site which are all dated to the Pleistocene epoch.[13] Eleodes split off from the rest of Amphidorini at least 8 to 15 million years ago in the Miocene, although this estimate is likely on the lower side due to low taxon sampling.[14]

Taxonomy

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Eleodes is the largest New World genus of darkling beetles comprising around 200 species divided up into the following 17 subgenera.[A][2][4][11][15][16][17][18][19]

Subgenera:

Incertae sedis:

Notes

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  1. ^ The subgenera and species within Eleodes are extremely likely to change in the coming years. This list is accurate as to what is defined in Bousquet et al. (2018).

See also

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References

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  1. ^ Bousquet, Yves; Thomas, Donald B.; Bouchard, Patrice; Smith, Aaron D.; Aalbu, Rolf L.; Johnston, M. Andrew & Steiner, Warren E. Jr. (2018). "Catalogue of Tenebrionidae (Coleoptera) of North America". ZooKeys (728): 1–455. Bibcode:2018ZooK..728....1B. doi:10.3897/zookeys.728.20602. PMC 5799738. PMID 29416389.
  2. ^ a b c d "Genus Eleodes - Desert Stink Beetles". bugguide.net. Retrieved 2023-07-05.
  3. ^ Clarke, Chris (September 13, 2013). "The Pinacate Beetle is Not Afraid of You". KCET. Retrieved April 13, 2022.
  4. ^ a b Triplehorn, Charles A.; Thomas, Donald B.; Smith, Aaron D. (2015). "A Revision of Eleodes Subgenus Eleodes Eschscholtz (Coleoptera: Tenebrionidae)". Transactions of the American Entomological Society. 141: 156–196. doi:10.3157/061.141.0111. S2CID 86220224.
  5. ^ a b Happ, George M. (1968-12-01). "Quinone and hydrocarbon production in the defensive glands of Eleodes longicollis and Tribolium castaneum (Coleoptera, Tenebrionidae)". Journal of Insect Physiology. 14 (12): 1821–1837. Bibcode:1968JInsP..14.1821H. doi:10.1016/0022-1910(68)90214-X. ISSN 0022-1910.
  6. ^ a b c "Darkling beetle | insect | Britannica". www.britannica.com. Retrieved 2023-07-05.
  7. ^ "Discovering a New Species in Nevada | Biodiversity Knowledge Integration Center". biokic.asu.edu. Retrieved 2023-07-05.
  8. ^ a b "THE LIFE HISTORY AND ECOLOGY OF THE PINACATE BEETLE, ELEODES ARMATUS LECONTE (TENEBRIONIDAE)" (PDF).
  9. ^ Schilman, Pablo E.; Kaiser, Alexander; Lighton, John R. B. (2008-01-01). "Breathe softly, beetle: Continuous gas exchange, water loss and the role of the subelytral space in the tenebrionid beetle, Eleodes obscura". Journal of Insect Physiology. 54 (1): 192–203. Bibcode:2008JInsP..54..192S. doi:10.1016/j.jinsphys.2007.09.001. ISSN 0022-1910. PMID 17936295.
  10. ^ a b Kramm, Russel A.; Kramm, Kenneth R. (1972). "Activities of Certain Species of Eleodes in Relation to Season, Temperature, and Time of Day at Joshua Tree National Monument (Coleoptera: Tenebrionidae)". The Southwestern Naturalist. 16 (3/4): 341–355. doi:10.2307/3670068. ISSN 0038-4909. JSTOR 3670068.
  11. ^ a b Aalbu, Rolf L. (2012). "A Revision of the Eleodes (Subgenus Caverneleodes) with New Species and Notes on Cave Breeding Eleodes (Tenebrionidae: Amphidorini)". Annales Zoologici. 62 (2): 199. doi:10.3161/000345412X652729. S2CID 59126250.
  12. ^ a b Slobodchikoff, C. N. (1978). "Habitat Use by Mimetic Coastal Tenebrionid Beetles". The American Midland Naturalist. 99 (1): 45–57. doi:10.2307/2424932. ISSN 0003-0031. JSTOR 2424932.
  13. ^ "Eleodes".
  14. ^ "Diversity and Distribution of the Desert Stink Beetles: Systematics of the Amphidorini LeConte, 1862 (Coleoptera: Tenebrionidae)" (PDF).
  15. ^ Blaisdell, Frank E. (1909). A monographic revision of the Coleoptera belonging to the Tenebrionide tribe Eleodiini inhabiting the United States, lower California, and adjacent islands. Washington: Govt. print. off.
  16. ^ "Studies in the Genus Eleodes Eschscholtz with a Revision of the Subgenus Melaneleodes Blaisdell and Omegeleodes, New Subgenus (Coleoptera: Tenebrionidae: Eleodini)". Transactions of the American Entomological Society. 2011. doi:10.3157/061.137.0309. S2CID 83697264.
  17. ^ Johnston, M. Andrew (2016). "Redefinition of the Eleodes Eschscholtz Subgenera Tricheleodes Blaisdell and Pseudeleodes Blaisdell, with the Description of a New Species (Coleoptera: Tenebrionidae)". Annales Zoologici. 66 (4): 665–679. doi:10.3161/00034541ANZ2016.66.4.018. S2CID 90125600.
  18. ^ "A Revision of Eleodes Subgenus Litheleodes Blaisdell (Coleoptera: Tenebrionidae) on JSTOR". www.jstor.org. Retrieved 2023-08-03.
  19. ^ Bousquet, Y.; Thomas, D. B.; Bouchard, P.; Smith, A. D.; Aalbu, R. L.; Johnston, M. A.; Jr., W. E. (2018). "Catalogue of Tenebrionidae (Coleoptera) of North America". ZooKeys (728): 1–455. Bibcode:2018ZooK..728....1B. doi:10.3897/zookeys.728.20602. PMC 5799738. PMID 29416389.
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