Leptothorax muscorum complex

Myrmicinae, Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia

Leptothorax muscorum complex in Washington

I have examined 66 different collections from 38 different localities scattered across Washington State. So far I see a great deal of variation, but I have not been able to find morphological clusters. Ward (2005, and Ants of California website) recognizes two species in California: L. calderoni and L. CA-01. The differences that distinguish these two species in California do not seem to differentiate species in Washington. I find a continuous gradation in shape of the petiole, from sharply triangular to increasingly blunt, either rounded or with a secondary posterior shoulder that delimits a sloping dorsal face. In some cases variation is intranidal. The pilosity varies in length. The head shape varies in the degree of convexity of the sides, such that some appear more quadrate than others. Overall size varies. I am calling all these muscorum complex for now.

The figure below attempts to illustrate some of this variation. The lowermost figures, below the line, may represent a distinct species. I am calling it JTL-001. The petiole is very sharply triangular in lateral view, with the anterior face sloping and the posterior face nearly vertical; the head is relatively short and broad, and it is a relatively uniform orange color. Specimens are from three different localities in the southern Cascades, all above 1000m elevation. It is sympatric with muscorum complex forms.

I only have four collections of muscorum complex with males. They vary greatly in size and degree of sculpturing.

Queen morphology generally parallels that of the workers with which they are associated.

Literature Cited

Ward, P. S. 2005. A synoptic review of the ants of California (Hymenoptera: Formicidae). Zootaxa 936:1-68.

Page author:

John T. Longino, The Evergreen State College, Olympia WA 98505 USA. longinoj@evergreen.edu

Date of this version: 23 July 2005.
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