User:Christopher.horacek/Dynastes grantii

Rough Draft Below

Includes taxonomic summary in main article

Dynastes grantii

The Western Hercules Beetle (Dynastes grantii, often misspelled as "granti") is a species of rhinoceros beetle that lives in Arizona, New Mexico, Utah and parts of northern Mexico. This species is known for it's grayish-white elytra, large size, and the characteristic horn of the adult males.

Description

Adult body sizes of both sexes vary from 35 to 60mm (apex of elytra to apex of thoracic horn), with captive bread individuals reaching up to 80mm. Coloration of the elytra varies from white to grayish-white, often with irregular black spots of various size and number. At high humidity levels, the elytra may appear black.

Dynastes grantii is sexually dimorphic, with the females lacking the characteristic horns of the male.

Life Cycle

Like other hercules beetle species, Dynastes grantii undergoes a six-stage lifecycle from egg to adult, with three larval instars and a single pupal stage. The time from egg to pupal eclosion is estimated to take approximately two years. The pupal stage lasts about 30 days. Adults emerge from the pupal chamber between the months of August through October and typically live between two and four months in the wild. In captivity, the adults may live up to nine months. After succefully mating the female oviposts over 100 eggs.

Distribution and habitat

Populations of Dynastes grantii may be found in southern Utah, Arizona, western New Mexico of the United States, and parts of Northern Mexico. This species typically inhabits highland forest habitats, at or above 1600m ASL.

Feeding Habits

Adults have been documented feeding on the cambium of ash trees. The beetles strip the bark from small branches and feed on the sap produced by the exposed cambium.

Similar species

Dynastes grantii belongs to the White Hercules beetle linage which includes five allopatrically distributed North American and Central American taxa, including Dynastes hyllus, Dynastes maya, Dynastes moroni, and Dynastes tityus . Despite differences in geographic origin and morphology, namely horn length and coloration of the elytra, Dynastes tityus and Dynastes grantii are very similar and it is possible for the two species to mate and produce hybrids. Some scientists believe that the two beetles are actually subspecies given the similiarties of the male genitalia.

Dynastes grantii is very similar morphologically to Dynastes hyllus, with differentiation between species often only possible through examination of geographic origin.

Distinction from D. hyllus

The body coloration of Dynastes hyllus is typically yelloiwsh to brownish where it is white to grayish-white in Dynastes grantii. The significant protrusion forward of the bottom tooth at the base of the thoracic horn in males of Dynastes hyllus is also a distinguishing factor between the two species. While Dynastes hyllus can be distinguished morphologically from Dynastes grantii, geographic origin is generally the strongest factor in correct identification. A compairsion between a male Dynastes grantii (left) and a male Dynastes hyllus (right) can be seen below.

Additional images

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  Adult male
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  Adult female
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  Adult male
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  Adult female

End Rough Draft

General Edits

Emergence dates (wording and specificity)

• " It appears in August or September, and grows to a size of 50–80 millimeters (2.0–3.1 in)".
  • This is badly worded. Adults emerge between August and September, and range in size from 35–60 millimeters (2.0–3.1 in). Adults do not grow to that size - their adult size is determined at emergence.
  • Needs a citation- Use SPECIFIED DATE Aug through October

Life Cycle (wording, specificity, and order)

• "The imagos usually live 2–4 months, and the larvae may spend 2–3 years before they turn into adults. "
  • Imagos typically live between 2-4 months\

Sentence Structure

• "They are nocturnal and often attracted to lights and they are among the biggest beetles found in the U.S."
  • Run-on sentence, needs cleaning up

Informational Topic Ideas

Life Cycle

Morphological Differences from D. Tityus (larval and adult)

Range

Offspring production

Potential References

• Arnold S. Menke, and Frank D. Parker. “Adult Feeding and Distribution of Dynastes Granti Horn (Coleoptera: Scarabaeidae).” The Coleopterists Bulletin, vol. 42, no. 2, 1988, pp. 161–164. JSTOR, www.jstor.org/stable/4008541. Accessed 24 Feb. 2021.
  • Primary provides information regarding range, though does highlight some interesting sources regarding separation from D. Tityus
• Ritcher, P.O. 1966. White Grubs and Their Allies, a Study of North American Scarabaeoid Larvae. Oregon State University Monograph Series No. 4: 1-219.
  • Provides morphological differences between larvae of D. grantii and D. tityus
• Krell, Frank-Thorsten & Krell, Victoria. (2015). Longevity of the Western Hercules Beetle, Dynastes grantii Horn (Coleoptera: Scarabaeidae: Dynastinae). The Coleopterists Bulletin. 69. 760-760. 10.1649/0010-065X-69.4.760.
  • Longevity
• Huang, Jen-Pan. (2017). The Hercules beetles (subgenus Dynastes, genus Dynastes, Dynastidae): a revisionary study based on the integration of molecular, morphological, ecological, and geographic analyses. Museum of Zoology, University of Michigan.
  • !!!!- This is an incredible resource, looks to provide more specific information in regards to distribution/size/taxonomic grouping
  • Potential range image provided within paper
• Jen-Pan Huang, L. Lacey Knowles, The Species versus Subspecies Conundrum: Quantitative Delimitation from Integrating Multiple Data Types within a Single Bayesian Approach in Hercules Beetles, Systematic Biology, Volume 65, Issue 4, July 2016, Pages 685–699, https://doi.org/10.1093/sysbio/syv119