Studies in Siricidae, especially of Europe and southern Asia (Hymenoptera, Symphyta)

Abstract

1. These studies were originally intended to form the basis of a world monograph of the Siricidae ; such a work cannot be completed under present circumstances.2. Two ratios are introduced as useful characters for separating species : the ovipositor/forewing ratio and the sawsheath/ovipositor ratio. These ratios were obtained from all specimens of all the species represented in the British Museum collections and the results are tabulated. They were found not to vary with the size of the insects.The former ratio is specially useful in the genus Urocerus, which has a long ovipositor, and the latter ratio in the genus Sirex, which has a shorter ovipositor.3. Keys are given to the genera of the world. Of Semenov's new genera, Xoanon is accepted but not Xanthosirex. A new genus Eriotremex is erected for certain Indo-Malayan species previously included in Tremex.4. Keys are given to the European species, which are compared critically with related species from other parts of the world. A key to the species of Eriotremex, gen. nov., is also given.5. Sirex noctilio, F., and S. juvencus, L., are recorded for the first time from North America and S. cyaneus, F., from the continent of Europe. The common Urocerus of the northern Palaearctic region is shown to be more closely related to the Nearctic U. gigas flavicornis, F., than to the central European U. gigas gigas, L., and is treated as a new subspecies—U. gigas taiganus, subsp. nov. U. gigas tibetanus, subsp. nov., is described from the Himalayas. U. sah, Mocsáry, is treated as a subspecies of U. augur, Klug, and U. cedrorum, Smith, as a synonym of U. augur augur, Klug.6. The British Siricidae are discussed, and it is suggested that U. gigas taiganus, subsp. nov., and the form of S. juvencus, L., with entirely black antennae may be native in the Caledonian forest.7. It is argued that modern Siricidae could not have been derived from the Jurassic Pseudosiricidae.8. The known Oriental and Himalayan Siricidae are listed and discussed. Urocerus multifasciatus, Takeuchi, and Eriotremex formosanus, Matsumura, are mentioned as two species originally described from Formosa but shown also to occur on the mainland. Urocerus niger, sp. nov., is described from the Himalayan region, and the name Eriotremex malayanus, sp. nov., is given to a form described without a name by Forsius from Malaya.9. Several errors in previous work on Siricidae are corrected.

Population structure and possible origin of Amylostereum areolatum in South Africa

“…Sirex noctilio and its symbiotic fungal associate, Amylostereum areolatum , are indigenous in the temperate regions of the Northern Hemisphere and are thought to be of Eurasian origin (Benson, 1943; Morgan, 1968; Spradbery & Kirk, 1978). In these regions, this insect–fungus complex is considered a secondary problem of little economic importance (Chrystal, 1928; Hanson, 1939; Hall, 1978; Spradbery & Kirk, 1978).…”

Diversity, population genetics, and evolution of macrofungi associated with animals

“…In return, the fungi provide a suitable environment, nutrients, and enzymes that are necessary for the survival and development of the insect larvae (Slippers et al 2003). In general, the woodwasps spend most of their life as burrowing larvae in host trees while adult wasps live only for a few weeks to mate and lay eggs in other trees every one to three years (Benson 1943; Morgan 1968). This type of insect–fungal complex does not usually result in obvious economic and ecological damage.…”

Revision of the African horntail genus Afrotremex (Hymenoptera: Siricidae)

“…Both genera share the loss of cerci in female, but Afrotremex has a shorter fore wing cell 2R1 relative to cell 3R1. Benson (1943), while maintaining T. hyalinatus as part of Tremex, suggested that it should be put in its own genus. Pasteels (1951) agreed and proposed Afrotremex to include T. hyalinatus and added a new species, A. violaceus, for the same reasons brought up by Benson.…”