Horntails (Siricidae) are important wood–boring insects with 10 extant genera and about 122 species worldwide. Adults and larvae of Siricidae are often intercepted at ports and are of concern as potential alien invasive species.
The family consists of 7 genera and 33 species in the New World: Eriotremex with one species, Sirex with 14 species, Sirotremex with one species, Teredon with one species, Tremex with two species, Urocerus with seven species, and Xeris with seven species. Five of these species have been accidentally introduced from the Old World: Eriotremex formosanus (Matsumura, 1912) into southeastern United States, probably from Vietnam; Sirex noctilio Fabricius, 1793, an important pest of Pinus spp., into eastern North America, Argentina, Brazil, and Uruguay from central Europe; Urocerus gigas (Linnaeus, 1758) into Chile, probably from Europe; Urocerus sah (Mocsáry, 1881) into northeastern North America, probably from southern Europe or North Africa; and Tremex fuscicornis (Fabricius, 1783) into Chile, probably from China.
Six new species are described: Sirex abietinus Goulet, n. sp.; S. hispaniola Goulet, n. sp.; S. mexicanus Smith, n. sp.; S. xerophilus Schiff, n. sp.; Xeris chiricahua Smith, n. sp.; and X. tropicalis Goulet, n. sp. Five species are re–instated: Urocerus caudatus Cresson, 1865, sp. rev.; U. nitidus T. W. Harris, 1841, sp. rev.; Sirex melancholicus Westwood, 1874, sp. rev.; S. obesus Bradley, 1913, sp. rev.; and S. torvus M. Harris, 1779, sp. rev. Eleven new synonyms are proposed: Neoxeris Saini and Singh, 1987, n. syn. of Xeris Costa, 1894; Sirex hirsutus Kirby, 1882, n. syn. of S. juvencus (Linnaeus, 1758); Urocerus zonatus Norton, 1869, n. syn. of S. nigricornis Fabricius, 1781; Sirex edwardsii Brullé, 1846, n. syn. of S. nigricornis Fabricius, 1781; Sirex fulvocinctus Westwood, 1874, n. syn. of S. nigricornis Fabricius, 1781; Sirex abaddon Westwood, 1874, n. syn. of S. nigricornis Fabricius, 1781; Sirex hopkinsi Ashmead, 1898, n. syn. of S. nigricornis Fabricius, 1781; Sirex leseleuci Tournier, 1890, n. syn. of S. torvus M. Harris, 1779; Sirex duplex Shuckard, 1837, n. syn. of S. torvus M. Harris, 1779; Sirex latifasciata Westwood, 1874, n. syn. of Urocerus albicornis (Fabricius, 1781); Xeris spectrum townesi Maa, 1949, n. syn. of X. indecisus (MacGillivray, 1893). Five new lectotypes are designated for: Paururus californicus Ashmead, 1904; P. pinicolus Ashmead, 1898; P. hopkinsi Ashmead, 1904; Sirex torvus M. Harris; and S. taxodii Ashmead 1904. Three changes in rank from subspecies to species level are proposed: Sirex californicus (Ashmead), n. stat., from S. juvencus californicus; Urocerus flavicornis (Fabricius), n. stat., from U. gigas flavicornis; and Xeris indecisus (MacGillivray), n. stat., from X. morrisoni indecisus. Two species are excluded from the New World Siricidae: Sirex juvencus (Linnaeus), and Xeris spectrum (Linnaeus); both species have been frequently intercepted in North America, but they are not established. One species is excluded from the Palaearctic Siricidae: Sirex cyaneus Fabricius. The European “Sirex cyaneus” is distinct from the American Sirex cyaneus; Sirex torvus M. Harris is the oldest name for this species.
We characterize the family based on all extant genera. The world genera are keyed and a reconstructed phylogeny is proposed. For genera not found in the New World, we provide a synonymic list, a description, and information about diversity with significant references. For genera in the New World, each genus includes the following (if available and/or pertinent): synonymic list, diagnostic combination, description for one or both sexes, taxonomic notes, biological notes, diversity and distribution, and references. Only New World Siricidae are treated at species level, each species includes the following (if available and/or pertinent): synonymic list, diagnosis, description of one or both sexes, geographical variation, taxonomic notes, origin of the specific epithet, biological notes, hosts and phenology (flight period data; a list of associated nematode and fungus species), and range.
DNA barcoding (cytochrome oxidase 1 – CO1) was shown to be a reliable identification tool for adults and larvae intercepted at ports. Larvae cannot be identified using classical morphological methods, but DNA barcoding can accurately distinguish larvae of all species tested to date. We include barcodes for 25 of the 33 New World species and consider in our taxonomic notes several Old World species as needed. DNA data has been most useful for confirming some morphologically similar species, associating specimens with two or three discrete color forms, and deciding the rank of some populations. The results have proved to be accurate and in agreement with species determined by classical morphological methods.
Nearctic, Neotropical, Siricidae, horntails, Afrotremex, Eriotremex, Sericosoma, Sirex, Sirotremex, Teredon, Tremex, Urocerus, Xeris, Xoanon, generic key (world), species key (Nearctic and Neotropical), distribution, biology, phylogeny.
