Pristomerus Curtis 1836
Creators: name: Klopfstein, Seraina
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Ichneumonidae
Pristomerus

description: Genus Pristomerus Curtis, 1836
Pristomeridia Ashmead, 1900
Pristocelus Szépligeti, 1905
Neopristomerus Viereck, 1912
Nesanomalon Morley, 1913
Type species: Ichneumon vulnerator Panzer, 1799
The ichneumonid subfamilies present in Australia can be identified using the key provided in Gauld (1984), which also includes a key to the Australian genera. As an alternative, a combination of the subfamily key in Hymenoptera of the World (Wahl, 1993), which also includes subfamilies that have not (yet) been reported from Australia, and the genus key by Townes (1971) can be used. The Cremastinae are small to medium-sized, slender to very slender ichneumonids with a laterally compressed metasoma, often long ovipositor, and usually bright colouration. Their fore wing pterostigma is usually rather wide, about 2.5 to 3 × as long as wide. They have one very distinctive feature, present in no other ichneumonids, which is that the spurs of the mid and hind tibiae are separated from the tarsal insertion by a sclerotized bridge, instead of being part of the same membranous area; assessing this character usually requires a microscope with good magnification.
Within the Australian Cremastinae, Pristomerus can be identified by the presence of thyridia on the second tergite. These are often obvious, but there are cases in which they are very small and inconspicuous. Such individuals might be mistaken for Trathala or even Temelucha specimens. Trathala usually has a straight or decurved ovipositor tip, but it can sometimes be sinuate as in Pristomerus. From Temelucha, Pristomerus specimens can be distinguished by the lower edges of the first tergite being parallel, separated by a visible portion of the first sternite for their entire length, while the lower edges of the tergite are expanded ventrally in Temelucha to partly cover the sternite. Neither Trathala nor Temelucha ever have a tooth ventrally on the hind femur, which is present in about one third of the Australian Pristomerus.
Thyridia are also present in a number of New World cremastine genera, but only Xiphosomella can also have a tooth on the hind femur. It can be distinguished from Pristomerus by the position of the thyridia, which are at or behind the middle of the tergite in the former and close to the base in the latter. Creagrura and Polyconus also have thyridia, but their fore wing areolet is closed and their first tergite is ventrally expanded as in Temelucha to cover part of the sternite. A phylogenetic analysis of the subfamily, ideally including molecular data, is to date missing, so the relationships between the different genera remain unknown. The Australian Pristomerus are remarkable for their large number of species without a tooth on the hind femur, which is almost always present in the other regions of the world. However, given the size of the genus in Australia, these species are not covered here.
Twenty-two Pristomerus species with a tooth on the hind femur could be identified among the Australian material. A dichotomous key is given here to aid in their identification, and descriptions of all species follow thereafter, in alphabetical order. If notable intra-specific variation was encountered, then it is reflected in the species sections, with values or states of the holotype given in brackets. Holotype label data is given in single quotes for each label, with a semicolon (";") representing line breaks and a slash ("/") separating different labels. In the case of measurements, the description sections contain the ranges of actually encountered values, while measurements that feature in the key, such as fore wing lengths, include some interpretation. As only few specimens were available for each species and will thus not represent the entire variation present, measurements were only used in the key when the values were very clearly apart, and reported thresholds should thus be conservative. In addition, an interactive identification key is available at http://www.xper3.fr/xper3GeneratedFiles/publish/identification/ 6866776222912430213/mkey.html. Plates detailing the habitus and selected characters for each species are shown in Figures 4–25, and maps with the collection data appear in Figure 26.
description: Published as part of Klopfstein, Seraina, 2016, Revising Australian Pristomerus (Hymenoptera, Ichneumonidae, Cremastinae): species with a tooth on the hind femur, pp. 201-238 in Zootaxa 4168 (2) on pages 203-204, DOI: 10.11646/zootaxa.4168.2.1, http://zenodo.org/record/375675