Picrocryptoides: a New Genus of the Tribe Mesostenini From Southern South America (Hymenoptera, Ichneumonidae)

The ic’hneumonid genus Trachysphyrus Haliday and its close relatives within the huge tribe Mesostenini are found in almost every part of the world. With one exception, however, the greatest number of these species seems limited to t’he Holarctic region. This exception is temperate and subtropical South America. The ancestors of the present-day South American Trachysphyr,us fauna appear to have entered the southern continent from the north. In tropical countries, such as Ecuador and Peril, they radiated only at high altitudes in the. Andes (approximately 8,ooo to. 14,ooo feet) and, to a lesser extent, in the. coastal desert and foothills on the. west. None, so far as known, penetrated the tropical cloud-forest and rainforest at lower elevations to. the. east. In t’he temperate regions of central and southern Argentina and Chile, on the contrary, this generic group o.f north-temperate extraction found a more suitable area in which to expand and produced a very complex radiation of close to IOO species, probably more than occur in any area of similar size and, certainly, in greater variety than in any o.ther region which the Trachysphyrus Group inhabits. Among this Apgentine and Chilean radiation are many speciesgroups which depart more or less radically from the customary definition of the genus Trachysphyrus. Some, although superficially bizarre in aspect, are not clearly to. be. distinguished from the main genus, to which they are often connected by species of intermediate character. Much of the group is still evolving rapidly and generic lines are not always clearly defined. Other series, however, present a combination o’f unusual features which so isolates them from their relatives that it would seem natural and convenient to. place them in separate genera. One such group, the new genus Picrocryptoides, is diagnosed below together with a description of its two known species.