Syntexis

Taxonomy

Family: Anaxyelidae
Family common name: incense cedar woodwasps
Subfamily: Syntexinae
Genus: Syntexis Rohwer, 1915
Subgenera: none

Background

The Anaxyelidae is largely a fossil family with only one living species. Syntexis libocedrii is a rarely found North American species with a small range and specific larval feeding habits. They are easily recognized by the cylindrical wasp-like body shape and distinctive white markings on the head and abdomen (Wickman 1967, Goulet 1992, Milius 2001).

Diversity

There is one described species of Syntexis, restricted to North America (Taeger et al. 2010).

Diagnostic characteristics

May be confused with

Syntexis libocedrii can be distinguished from Siricidae by the lack of Siricidae sawflies; on tergite 10 in females, sternite 9 in males ">cornus and evenly sloping pronotum shape, from Cephidae by the presence of cenchri, and from all other families by the equal lengths of the second and third antennal segments (Goulet 1992).

Exotic pest species of concern

none

Host associations

Larvae characteristically feed on the wood of trees of Calocedrus decurrens (incense cedar), and for many years this was the only recorded host. However, S. libocedrii has also been reared from Juniperus occidentalis (western juniper) and been observed ovipositing in Thuja plicata (western red cedar) (Westcott 1971, Smith 1993, Middlekauff 1974).

Life history

Syntexis libocedrii has a unique life history among sawflies; the preferred oviposition site for this species is wood that has been recently burnt. The female oviposits 1–5 eggs in close proximity at a depth of 1–4 mm in freshly scorched wood pieces. In laboratory settings, females will not deposit eggs into un-burnt wood, further indicating indicating this species is fire-adapted (Wickman 1967, Milius 2001).

After hatching, the larvae immediately begin to bore into the sapwood and create a curved gallery, often U-shaped, on average 50 mm in length. Larvae are cylindrical and white with an apical horn-like structure, similar to larval Siricidae. At maturity, the prepupa enters a pupal chamber, near the surface of the wood. Adults emerge after diapause and pupation in summer. Though in a laboratory setting this species had a 1-year life cycle, in the field adults were not observed emerging until the second and third year of development (Wickman 1967, Middlekauff 1974).

Distribution

World: This genus is represented only in North America (Taeger et al. 2010).

North America: Most Syntexis libocedrii records are from northern California, specifically in the Sierra Nevada and Siskiyou mountain ranges. The species has also been recorded from southern Oregon and British Columbia (Westcott 1971, Goulet 1992). Two records also exist for Idaho, although they are from a bird's stomach (Westcott 1971). The species may also occur in Washington State.

Map data from: GBIF.org (26 June 2019) GBIF Occurrence Download Syntexis, the Smithsonian National Museum of Natural History Entomology Collection (USNM) and the Oregon State Arthropod Museum (OSAC)

Details about data used for maps can be found here.

Syntexis libocedrii female lateral habitus; photo by Q. Baine, WSDA

Syntexis libocedrii female lateral habitus; photo by Q. Baine, WSDA

Syntexis libocedrii female dorsal habitus; photo by Q. Baine, WSDA

Syntexis libocedrii female dorsal habitus; photo by Q. Baine, WSDA