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05 de junio de 2022

A tentative key to workers in the Formica sanguinea species group

The following is based on specimens hosted on AntWeb and information described by AntWiki. It is likely not a complete or comprehensive guide to identification and will need review but is to the best of my knowledge accurate to current published data.

NOTE: The species Formica obtusopilosa and Formica perpilosa resemble sanguinea-group species in that they may have a clypeal notch. However, they are currently considered to belong to the neogagates species group and can typically be distinguished by their small size, higher-set eyes, and more rounded heads.

1.
Palearctic, typically European but reportedly occasionally occurring in Central Asia -- Formica cf. sanguinea

Nearctic: throughout mainland North America between Alaska and northern Mexico. Rare or not occuring in southeastern states -- (2)

2.
Entire body including gaster mostly or entirely concolorous and shining -- (3)

Body clearly bicolored with brown or black gaster; if appearing somewhat concolorous, gaster pubescent -- (4)

3.
Intensely red or orange in coloration, occuring locally in northwestern states from Washington to Oregon and Montana, possibly north into British Columbia -- Formica curiosa

Darker and less uniform in coloration. Crest of propodeum angulate and length of clypeus from frontal area to clypeal margin notably exceeding length of frontal lobes. Uncommonly collected, occuring in midwestern states or occasionally in New England -- Formica creightoni

4.
Mesonotum small or "saddle-backed" in profile, forming a small but distinct step up from pronotum; crest of petiole lacking erect setae -- (5)

Mesonotum mostly flush with pronotum, forming an uninterrupted curve or if appearing "saddle-backed" setae are present on crest of petiole -- (6)

5.
Bicolored or mostly concolorous and brownish. Commonly collected throughout eastern United States and presumably occurring in eastern Canada; distribution as far southeast as Georgia and as far west as Utah but most often recorded between Illinois and North Carolina to Maine -- Formica subintegra

Bicolored or very weakly if ever concolorous and head dark. Mesonotum significantly smaller than pronotum. Rarely recorded, presumably only occurring in Arizona, Utah, and Colorado -- Formica emeryi

6.
Very few or no erect setae on gaster. Petiolar node broad, typically as wide as propodeum, and resembling a fan, lacking setae on the crest. Widespread, occurring throughout United States and Canada but not present in central and southeastern states (Nebraska south to Texas and east to North Carolina, present sporadically in Appalachia). Especially common at higher elevations in the west including the Rocky, Cascade, and Sierra Nevada Mountains; in the east most often collected in the New England and Great Lakes regions -- Formica aserva

Several erect setae present on dorsum and gaster. Petiolar node smaller with at least a shallow notch and/or setae present on the crest -- (7)

7.
Erect setae on gaster and mesosoma short and/or stiff, bristle-like with inconsistent tapering; petiole with sharp crest. Eastern United States with populations in Colorado and New Mexico -- Formica rubicunda

Erect setae on gaster and mesosoma longer and/or evenly tapered -- (8)

8.
Erect setae on gaster thick and gaster pubescent. Antennal scapes shorter than total length of head. Believed to occur from Quebec south to North Carolina and no further west than the Rocky Mountains except for possibly dubious southwestern populations reported in Utah, Colorado, Arizona, & New Mexico -- Formica pergandei

Erect setae on gaster thinner, longer, and usually less dense -- (9)

9.
Gaster pubescent; propodeum smoothly sloping and lower than crest of petiolar node. Hairs on pronotum appear the same as those on the gaster. Commonly collected in western United States and Canada, especially along the Rocky, Cascade, and Sierra Nevada Mountains -- Formica puberula

Gaster sometimes less pubescent and propodeum more angulate from side profile. Occurring only in central southwestern United States, at most Idaho to Texas -- (10)

10.
Petiolar node unremarkable and blunt, few or no erect setae on mesonotum. Setae on pronotum typically short and blunt -- Formica wheeleri

Petiolar node resembling a spade from side profile, several erect setae present on mesonotum -- Formica gynocrates

Special acknowledgement to @arman_ , @mettcollsuss, and @mazmurlo for input and support

References:
All images are linked to their respective files on AntWiki which contain appropriate reference and licensing information. Listing all the images here would be tedious and take up too much space.

Key to New England Formica. AntWiki. (2018). Retrieved June 5, 2022, from https://antwiki.org/wiki/Key_to_New_England_Formica

Ellison, A. M., Gotelli, N. J., Farnsworth, E. J., & Alpert, G. D. (2012). Field guide to the ants of New England. Yale University Press.

Publicado el junio 5, 2022 10:28 TARDE por critters_pnw critters_pnw | 0 comentarios | Deja un comentario

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