"Falcichenumon"

In 2019, I made an exciting discovery during a major sorting effort of Nearctic Ichneumoninae in the ichneumonid collection of Utah State University: the first specimen of "Falcichneumon". This single male was found in a riparian area near Sedona, Arizona. At the time, I set it aside as an aberrant and possible new genus, but no further work was undertaken until 2021 when another male specimen as discovered.

The second specimen was from a VFIT sample collected by Bill Warner, the inventor of VFITs. It was found in the Huachuca Mountains in southeastern Arizona. The discovery of this second specimen spurred me to begin work on the generic description.

While a description based solely on morphology would be sufficient, I am conducting a more integrative study to place Falcichneumon within a phylogenetic context in Ichneumoninae. A further aim is to show that it is likely not derived within the most closely related genus, Tricholabus.

In the United States, Falcihneumon luteopterus can recognized based on its coloration alone. There is no other ichneumonine species with a black body and yellow wings. However, in Mexico F. luteopterus may cooccur with Ichneumon bilimeki which are similarly colored. The two can easily be separated based on the sickle-shaped mandible of the former and normal, slightly narrowed bidentate mandible of the latter.

Biology

The biology of Falcicneumon is entirely unknown. Unfortunately, no female specimens have yet been discovered which would give some insight as to whether the genus attacks larvae or pupae. Another aspect of the biology which is unclear is how Falcicneumon and several other genera use the sickle-shaped mandibles. A straightforward but speculative assumption is that they are being used to emerge from the host pupa or substrate within which the host pupa is hidden.

Diagnosis

• mandible unidentate and sickle-shaped
• ventral margin of clypeus weakly concave
• male flagellum with bristle-ridges
• hypopygium without medial process
• gonoforceps not enlarged

Etymology

Generic name derived from falx (Latin) meaning sickle and Ichneumon. Species name derived from luteus (Latin) meaing yellow and pteron (Greek) meaning wing.