Tramea darwini

Kirby, 1889

Striped Saddlebags

Tramea darwini is a in the Libellulidae, commonly known as the Striped Saddlebags. An insular has been documented exhibiting exceptional behavioral diversity in oviposition strategies, with four distinct modes recorded—more than any other studied population of the . This species belongs to a genus characterized by saddlebag-like markings on the hindwings.

Tramea darwini perched by John Rosford. Used under a CC BY 4.0 license.

Striped Saddlebags - Tramea darwini, Santiago Island, Galapagos, July 7, 2021 (52388024701) by Judy Gallagher. Used under a CC BY 2.0 license.

Pronunciation

How to pronounce Tramea darwini: //ˈtræ.mi ə ˈdar.wɪˌni//

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Identification

As a member of the Tramea, this likely displays the characteristic dark patches at the base of the hindwings that give saddlebags their . The specific epithet 'darwini' honors Charles Darwin, though this does not itself aid field identification. Distinguishing T. darwini from requires examination of wing venation, abdominal patterning, and the precise shape and extent of the hindwing patches. The common name 'Striped Saddlebags' suggests longitudinal striping on the that may separate it from other Tramea species.

Images

Habitat

Documented from pond on Isabela Island in the Galápagos, where an insular has been studied. GBIF records indicate presence in diverse Colombian departments including Antioquia, Chocó, and Vaupés, suggesting adaptability to varied Neotropical freshwater environments. The Vermont, USA record likely represents a vagrant or misidentification given the ' established Neotropical distribution.

Distribution

Primary distribution in northern South America, with confirmed records across numerous Colombian departments. The has been studied in detail from an insular in the Galápagos (Isabela Island). GBIF data indicate presence in the Caribbean region (Archipiélago de San Andrés, Providencia y Santa Catalina) and mainland South America. A single record from Vermont, USA is noted but its status as established population or vagrant is unclear.

Behavior

An insular Galápagos exhibits four distinct oviposition strategies: (1) tandem oviposition in tandem, (2) female oviposition alone, (3) female oviposition under non-contact guarding by male, and (4) other variants. The 'tandem–oviposition–tandem' mode—though most frequently observed—was found to be less efficient than solitary female oviposition or oviposition under non-contact guarding. This paradox suggests sexual conflict, with males and females favoring different behavioral strategies. This behavioral diversity exceeds that recorded for any other Tramea population studied.

Similar Taxa

Tramea lacerataBlack Saddlebags shares the characteristic hindwing patches and overlapping North American/Neotropical range; requires careful examination of abdominal striping and wing patch for separation.
Tramea onustaRed Saddlebags occurs in overlapping regions and similar ; reddish coloration and wing patch details differ from T. darwini.
Brachymesia herbidaSympatric in Galápagos pond ; also exhibits multiple oviposition strategies though with lower behavioral diversity than T. darwini in the same insular .

More Details

Behavioral Diversity Significance

The four oviposition modes documented in the Galápagos insular represent the highest behavioral diversity recorded for any Tramea population. This challenges assumptions that -poor island exhibit reduced behavioral complexity, instead suggesting that underfilled behavioral may promote diversification of reproductive strategies.

Sexual Conflict

The documented inefficiency of the most common male-favored tandem strategy compared to female-favored alternatives provides empirical support for sexual conflict theory in odonate reproductive .