Platylabini (Hymenoptera: Ichneumonidae: Ichneumoninae) of the south-eastern United States: new distributional data, taxonomic notes, illustrated keys, and an annotated catalogue of the genera and species Author Dal Pos, Davide Author Heilman, Victoria Author Welter-Schultes, Francisco text Journal of Natural History 2022 2022-12-02 56 1869 1938 http://dx.doi.org/10.1080/00222933.2022.2134061 journal article 202628 10.1080/00222933.2022.2134061 7b46e09e-c06f-438a-8621-f79aafa3d8c1 1464-5262 7397619 Linycus Cameron, 1903 Linycus Cameron, 1903: 234 . Type species: Linycus rufipes Cameron, 1903 , by monotypy. Comparative diagnosis From all the other four Nearctic Platylabini genera with small, circular or roundish propodeal spiracles – Apaeleticus , Carlsonia , Cyclolabus and Neolinycus – Linycus can be easily distinguished by the combination of different features. The subobsolete gastrocoeli, represented only by narrow and shallow, oblique, longitudinal depressions, bearing some coarse, irregular, longitudinal rugae ( Figure 15d ), set Linycus apart from Cyclolabus (which has strongly pronounced gastrocoeli, with thyridia larger than the space between them ( Figure 13e )) and, in addition to these features, the presence of distinct propodeal carinae ( Figure 15d ) allows separation from Apaeleticus (which has a strongly reticulated and completely areolated propodeum ( Figure 7a )). Lastly, Linycus differs from Carlsonia by the structure of the head, which is not as broad and strongly convex, but narrower and less bulging, and from Neolinycus Heinrich , by the structure of the temples, which are not strongly reduced, but moderately developed ( Figure 15b ) ( Heinrich 1961 , 1962b , 1977 ; Tereshkin 2009 ). Range and diversity The genus Linycus has a Holarctic and Oriental distribution, with four species in the Nearctic, only one occurring in the south-eastern United States ( Heinrich 1962b , 1971 , 1975 ; Yu et al. 2016 ).