Thyreodon, BRULLE, 1846

Gauld, Ian D. & Janzen, Daniel H., 2004, The systematics and biology of the Costa Rican species of parasitic wasps in the Thyreodon genus-group (Hymenoptera: Ichneumonidae), Zoological Journal of the Linnean Society 141 (3), pp. 297-351 : 315

THE GENUS THYREODON BRULLÉ

Thyreodon Brullé, 1846: 150 . Type species: Thyreodon cyaneus Brullé , by subsequent designation, Hooker, 1912: 107.

Athyreodon Ashmead, 1900: 87 . Type species: Athyreodon thoracicus Ashmead (= Ophion atriventris Cresson ), by original designation.

Diagnosis: Large, slender to moderately stout insects, fore wing length 15.2–27.8 mm, black, black and yellow, metallic blue, red-brown or orange and black in colour with blackish or mottled wings ( Figs 3–6 ). Head in anterior view with labio-maxillary complex not elongate, barely projecting ventrally; maxillary palp with palpomere II grossly inflated and often slightly flattened; clypeus with margin out-flared, thin, centrally with an obtuse to moderately acute point; ocelli from small, the lateral ones separated from eye by more than their own diameter, to very large, the lateral ones contiguous with the eye; occipital carina complete dorsally, ventrally usually not reaching hypostomal carina, rarely joining it. Antenna short and moderately stout, setaceous, the central flagellomeres from slightly elongate to strongly transverse. Pronotum with hind margin mediodorsally thickened and subquadrate in profile, sometimes with upper anterior margin projecting strongly forwards, often with anterior margin reflexed; notauli usually sharply impressed and reaching beyond centre of mesoscutum; lateral part of metanotum weakly swollen and not carinate; propodeum grossly inflated, overhanging a reduced metapleuron, posteriorly, mediodorsally with a shallow to very deep median longitudinal furrow. Hind coxa small, its apex more or less level with hind margin of propodeum. Fore wing with abscissa of vein 1 m-cu distal to bulla longer than abscissa of M between 2 m-cu and 3 rs-m. Metasoma with tergite II slightly to obviously longer than tergite III; male with dorsal margin of clasper weakly to strongly notched; aedeagus simple or with a sharp subapical lateral keel; male subgenital plate slightly elongate, posteriorly convex, sometimes thickened.

Remarks: Thyreodon is primarily Neotropical, although one species occurs in the Nearctic as far north as southern Canada where it is recorded as a parasitoid of Lapara coniferarum , L. bombycoides and Paonias excaecatus (Sphingidae) ( Hooker, 1912). Four other species, T. fernaldi Hooker , T. ornatipennis Cresson , T. apricus and T. rivinae , also extend from Mexico into the southern USA ( Carlson, 1979; Porter, 1980, 1984). Thyreodon is the most species-rich genus in the genus-group, and includes many more species than all the other genera combined. It is well represented in Central America, and 21 species have been found in Costa Rica. However, there may be hundreds more in South America, including the widely distributed typespecies T. cyaneus ( Fig. 2 ). Despite collecting efforts embracing hundreds of Malaise trap years in all Costa Rican ecosystems and habitats ( Hanson & Gauld, 1995), about 55% of the Costa Rican species have never been collected in Malaise traps. Furthermore, careful observations of host range coupled with close morphological examination has shown that several fairly wellknown, slightly variable species, such as ‘ T. atriventris ’ and ‘ T. laticinctus ’, are in reality complexes of morphologically quite uniform, similar species, each parasitizing different but fully sympatric species of hosts.

Figures

Figure 2. Whole insect, lateral. Thyreodon cyaneus. Illustration reproduced with the kind permission of the American Entomological Institute.

Figures 3–6. Thyreodon species, whole insects, lateral, showing major colour patterns found in the genus. 3. T. atriventris. 4. T. laticinctus. 5. T. walkerae. 6. T. schauffi. Scale bar = 5 cm.