Tenthredo maxima

(Norton, 1867)

Tenthredo maxima is a in the Tenthredinidae, characterized by a broad connection between and lacking the narrow ' waist' of other Hymenoptera. The species comprises two recognized : T. m. maxima and T. m. retura (formerly T. retura). It occupies a unique phylogenetic position within the , forming its own species group with no close relatives in North America. The species has been extensively studied for its geographic variation across western North American mountain systems.

Tenthredo maxima P1060347a by
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Tenthredo maxima2 by JerryFriedman. Used under a CC BY-SA 3.0 license.

Tenthredo maxima P1220900a by
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Pronunciation

How to pronounce Tenthredo maxima: //tɛnˈθriːdoʊ ˈmæk.sɪ.mə//

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Identification

can be distinguished from other Hymenoptera by the broad, unconstricted connection between and . Within the Tenthredo, T. maxima is placed in its own group separate from the originalis group. The two (T. m. maxima and T. m. retura) can be differentiated based on morphological characters across 12 distinct . Females possess a saw-like ovipositor for inserting into plant tissue, but lack a stinger. Larvae have seven pairs of , distinguishing them from caterpillars which have five or fewer pairs.

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Habitat

Montane meadows or semi-open forest in the montane zone. Associated with deciduous forest edges and aspen stands in mountainous regions.

Distribution

Western North America: Rocky Mountains, Cascade Range, and Sierra Nevada. Specific distribution records include Alberta, British Columbia, and Yukon in Canada.

Seasonality

tend to appear in late summer and early autumn, later in the season than many other Tenthredo which are more abundant in spring.

Similar Taxa

Other Tenthredo speciesMany Tenthredo occur in the same geographic range and share similar flower-visiting . T. maxima is distinguished by its unique species group placement and later seasonal activity.
Vespid wasps (Vespidae)T. maxima and other are frequently mistaken for due to similar coloration patterns that mimic stinging . Distinguished by the broad - connection and lack of a stinger in females.
Lepidoptera caterpillars larvae are often mistaken for caterpillars due to similar foliar feeding . Distinguished by having seven pairs of versus five or fewer in caterpillars.

More Details

Subspecies

Two recognized: T. m. maxima and T. m. retura (formerly described as T. retura Ross, now synonymized). The subspecies show geographic structuring across 12 distinct based on analysis of 24 morphological characters from 2405 specimens.

Phylogenetic position

Forms its own group within Tenthredo with no close relatives in North America; originally included in the originalis group but now recognized as distinct.

Zoogeographic history

Pleistocene glacial cycles have influenced the current distribution and structure across the mountain ranges of western North America.