Sirex mexicanus

Taxonomy

Family: Siricidae
Subfamily: Siricinae
Genus: Sirex Linnaeus, 1760
Species: Sirex mexicanus Smith, 2012
Common names: none

Background

Sirex mexicanus is a somewhat rare species from Mexico (Schiff et al. 2012).

Diagnostic characteristics

See Sirex for genus-level diagnostic characteristics.

Females:

Males:

May be confused with

Sirex mexicanus females can be distinguished from S. xerophilus by the transverse ridges on the posterior half of the mesoscutum. The males can be recognized by the light colored antennae, coxae, and clear fore wing (Schiff et al. 2012).

Morphological and geographical variation

none recorded

Host associations

unknown

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. mexicanus were collected in mid-June and mid-July (Schiff et al. 2012).

Distribution

World: North America

North America: Sirex mexicanus is only known from Mexico City and northern Mexico (Schiff et al. 2012).

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

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

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

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

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

Sirex mexicanus male antenna; photo by H. Goulet, CNC

Sirex mexicanus male antenna; photo by H. Goulet, CNC

Sirex mexicanus mesoscutum; photo by H. Goulet, CNC

Sirex mexicanus mesoscutum; photo by H. Goulet, CNC

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

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