Sussudio, Boudinot & Borowiec & Prebus, 2022

Boudinot, Brendon E., Borowiec, Marek L. & Prebus, Matthew M., 2022, Phylogeny, evolution, and classification of the ant genus Lasius, the tribe Lasiini and the subfamily Formicinae (Hymenoptera: Formicidae), Systematic Entomology 47, pp. 113-151 : 142-143

Genus † Sussudio gen.nov.

Type and included species. † P. boreus Wheeler, 1915 . Original designation.

ZooBank LSID. http://zoobank.org/urn:lsid:zoobank.org:act: BFF515E7-9966-443F-8A34-555A4B41906B

Definition (worker).

1. With characters of the Formicinae (Note 1).

2. Cranium size variable, width somewhat broader than to about twice that of mesosoma (Note 2).

3. Mandible triangular, with 7–8 teeth.

4. Dorsal mandibular groove extending along lateral mandibular margin in dorsal view.

5. Palps reduced, not reaching midlength of postgenal bridge.

6. Frontal carinae raised above antennal toruli.

7. Antennal toruli abutting posterior clypeal margin.

8. Antennomere count unknown (Note 3).

9. Antennomere III longer than broad.

10. Compound eyes situated posterior to head midlength.

11. Compound eyes not enormous and long axes subparallel.

12. Ocelli minutely present or absent.

13. Promesonotum domed, raised well above propodeum.

14. Metanotal groove well-developed.

15. Petiolar foramen in profile view clearly raised and margined with conspicuous thickened carina or lip.

16. Petiolar node squamiform, tall; dorsoventral height equal to or possibly exceeding dorsum of propodeum.

17. Abdominal segment III without raised tergosternal fusion.

Notes on definition:

Note 1. Several characters were not possible to evaluate. These include the following: Reduction of third tooth from mandibular apex, palp formula, the metapleural gland, ventral length of the petiolar foramen, relative separation of the meso- and metacoxae, presence or absence of setal double-row on ventral tibial surfaces, petiolar apodeme conformation, cross-sectional shape of the petiolar sternum, and presence or absence of the posthelcial sulcus.

Note 2. The massive head of † P. boreus led Wheeler (1915) to erroneously assume that the specimens were majors of Pseudolasius ; Wheeler did note the posteriorly set eyes of † P. boreus , one of the distinctions between it and Pseudolasius , but vacillated based on the insufficient knowledge of the latter genus at that time.

Note 3. The examined specimens are missing their terminal antennomeres, and no previous descriptions of † P. boreus include an antennomere count.

Etymology. Asimplification of ‘pseudo- Pseudolasius ’ inspired by the musician Phil Collins. Masculine.

Comments. † Sussudio boreus comb.nov. was previously placed in the Lasiini ( Emery, 1925, Dlussky & Fedoseeva 1988, Bolton, 1994), and has been considered to be a member of the genus Pseudolasius ( Wheeler, 1915; LaPolla & Dlussky, 2010). Based on an examination of a syntype (GZG-BST04646) and a nontype (NHMW1984-31-211) worker, as well as the original description from Wheeler (1915), we reject both placements. Neither specimen can be mistaken due to the unique combination of characters they display, including setation, high petiolar nodes, massive crania, and mesosomal form. † Sussudio boreus does not display the modifications of the third abdominal segment characteristic of the Prenolepis genus group, also rejecting its original placement in Pseudolasius (see diagnostic Note 2 above). † Sussudio is excluded from the Lasiini overall by two additional characters: (i) The petiolar node, which is completely vertical and very tall dorsoventrally, is as tall as or possibly taller than the propodeum; and (ii) the raised and conspicuously lipped petiolar foramen. No lasiine, extant or extinct, has such a tall petiolar node, nor do any species display the petiolar foramen conformation observed in † Sussudio . We cannot confidently place † Sussudio in any extant tribe, therefore, we consider † Sussudio incertae sedis in the Formicinae . As with other fossil taxa, which are of uncertain placement in the Formicinae , micro-CT scanning could be used to evaluate the form of the helcium and third abdominal sternum.