Cariridris bipetiolata

A real surprise was the record of a Formicidae from the Lower Cretaceous of the Crato Formation (Brandao et al., 1989). However, the attribution of the specimen was at first not very confident at all, and is still disputed to this day (J. Rust, personal communication). The preservation of the holotype is relatively poor, with indistinct edges and incomplete cephalic area. Furthermore, it is not possible to see whether the specimen had wings or not. Subsequently, the animal has been mistaken for a representative of the Ampulicidae (‘Sphecidae’), which often have an extremely similar general habitus (Figure 11.72e). However, the structure of the petiolus indicates that the fossil indeed belongs to the Formicidae of the subfamily Myrmeciinae (bulldog ants), whose distribution is now limited to Australia. As it was not possible to attribute the new fossil species to the single Recent genus Myrmecia, it was named Cariridris bipetiolata by Brandao et al. (1989) (Osten, 2007).

Two further specimens of Cariridris may have been discovered while examining fossil material for the present volume (that is, Osten, 2007). There is no doubt that these two fossils also belong to the same genus and species Cariridris bipetiolata (Figure 11.77). The specimen SMNS 66565 (Plate 15m) is much better preserved than the holotype, and supports the attribution to Formicidae–Myrmeciinae (petiolus and head structures). The absence of wings in this specimen is of course no valid evidence against such an attribution.

Distribution
This taxon was described from.

Nomenclature

 * †. †Cariridris bipetiolata Brandão & Martins-Neto, in Brandão, et al. 1990: 201, figs. 1-3 (q.) BRAZIL (Ceará, Cretaceous).
 * Status as species: Brandão, 1990a: 313; Brandão, 1991: 337; Bolton, 1995b: 134.
 * Excluded from Formicidae, incertae sedis in ACULEATA: Grimaldi, Agosti & Carpenter, 1997: 7; Ward & Brady, 2003: 362.
 * Excluded from Formicidae, incertae sedis in “sphecid wasp subfamily” Ampulicinae: Rasnitsyn, 2002: 249; Dlussky & Rasnitsyn, 2002: 418; Dlussky, 2012: 288 (in text).
 * In Formicidae, Myrmeciinae: Osten, 2007: 353.

Taxonomic Notes
Note that Dlussky & Rasnitsyn (2003) treated this species as belonging to the family Sphecidae rather than Formicidae. They state: C. bipetiolata as described and figured by Brandão et al. (1989) looks very similar to an unnamed Santana fossil kept at the American Museum Natural History (New York, New York, USA) and described as belonging to either Sphecidae (Ampulicinae) or Dryinidae (Darling, Sharkey, 1990). One of us (APR) jointly with W.J. Pulawski of the California Academy of Sciences (San Francisco, California, USA) have studied that fossil (AMNH 44108) and found it belonging to Sphecidae (probably to subfamily Ampulicinae) rather than to Formicidae. That is why we maintain here our earlier conclusion that Cariridris is a genus of Sphecidae (Rasnitsyn, 1990; Dlussky, 1998).

Dlussky (2012) followed the treatment of Dlussky and Rasnitsyn (2003) and considered this species to be incertae sedis in Ampulicidae. However, it appears he was unaware of the specimens examined by Osten (2007) (as he does not cite this paper). Osten's taxonomic placement is followed here, with the species is placed back within the Formicidae and in the subfamily Myrmeciinae.