Sirex xerophilus

Taxonomy

Family: Siricidae
Subfamily: Siricinae
Genus: Sirex Linnaeus, 1760
Species: Sirex xerophilus Schiff, 2012
Common names: none

Background

Sirex xerophilus is a rare western Nearctic species with black body and legs. The name comes from the Greek for “dry loving” because of its association with dry ecosystems (Schiff et al. 2012).

Diagnostic characteristics

See Sirex for genus-level diagnostic characteristics.

Females:

Males:

May be confused with

Sirex xerophilus females can be distinguished from most Sirex by the completely black legs, black abdomen, and clear fore wing, and from S. mexicanus by the large, coarse mesoscutum pits. Males can be distinguished from S. californicus and S. obesus by the black coxae and reddish-brown antennae (Schiff et al. 2012).

Morphological and geographical variation

none recorded

Host associations

Sirex xerophilus has been reared from Pinus ponderosa (ponderosa pine) (Schiff et al. 2012).

Life history

Female Sirex harbor symbiotic basidiomycete fungus in abdominal glands called mycangia. During oviposition, the site is inoculated with the fungus, which begins to decompose the surrounding wood. Larvae feed on the fungus, and in the process bore galleries through the wood (Johnson 1930, Schiff et al. 2012).

Larvae are creamy white and grub-like in appearance with a dark head capsule. As with adults, larvae possess a short dorsal horn on the posterior end of the body. The larvae bore galleries into wood, feeding until pupation and subsequent emergence. Throughout this process, the larvae use their horn to pack the tunnel behind them with sawdust. Emergence holes are perfectly circular. The fungal symbiont is carried in specialized organs in female larvae that develop into the mycangia after metamorphosis (Schiff et al. 2012).

The few existing specimens of S. xerophilus have been collected in September and November (Schiff et al. 2012).

Distribution

World: North America

North America: Sirex xerophilus is recorded in Colorado, Utah, and Chihuahua, Mexico (Schiff et al. 2012).

No specific locality data was available for mapping the range of this species at the time of publication.

Sirex xerophilus female lateral habitus; photo by H. Goulet, CNC

Sirex xerophilus female lateral habitus; photo by H. Goulet, CNC

Sirex xerophilus male lateral habitus; photo by H. Goulet, CNC

Sirex xerophilus male lateral habitus; photo by H. Goulet, CNC

Sirex xerophilus fore wing; photo by H. Goulet, CNC

Sirex xerophilus fore wing; photo by H. Goulet, CNC

Sirex xerophilus ovipositor pits; photo by H. Goulet, CNC

Sirex xerophilus ovipositor pits; photo by H. Goulet, CNC

Sirex xerophilus mesoscutum; photo by H. Goulet, CNC

Sirex xerophilus mesoscutum; photo by H. Goulet, CNC