Eocamponotus Boudinot, 2024

Boudinot, Brendon E., Bock, Bernhard L., Weingardt, Michael, Troeger, Daniel, Batelka, Jan, LI, Di, Richter, Adrian, Pohl, Hans, Moosdorf, Olivia T. D., Jandausch, Kenny, Hammel, Joerg U. & Beutel, Rolf G., 2024, Et latet et lucet: Discoveries from the Phyletisches Museum amber and copal collection in Jena, Germany, Deutsche Entomologische Zeitschrift 71 (1), pp. 111-176 : 111

Genus † Eocamponotus Boudinot gen. nov.

Type species.

† Eo. mengei (Mayr, 1868) by original designation.

Note.

Incertae sedis in Camponotini .

3.3.2.4. Subfamily Myrmicinae Lepeletier de Saint-Fargeau, 1835

3.3.2.4.1. Genus Crematogaster Lund, 1831

I. Species retained in Crematogaster .

Copal fossil: Identifiable to species:

A. African copal [Holocene, <36 Kya ( Solórzano-Kraemer et al. 2020)].

1. Cre. sp. THIS STUDY. [w].

II. Fossils excluded from Crematogaster :

Genus † Incertogaster Boudinot, gen. nov., incertae sedis in Myrmicinae . [Note 1].

Type species: † Inc. primitiva (Radchenko & Dlussky, 2019), by original designation.

B. Kishenehn formation [USA, Montana; 47.8-41.3 Mya].

(1.) † In. aurora (LaPolla & Greenwalt, 2015). [q]. [Note 2]. Comb. nov.

C. Rovno amber [Ukraine; Eocene, 38.0-33.9 Mya].

(2.) † In. praecursor (Emery, 1891). [m]. [Note 3]. Comb. nov.

D. Sicilian amber [Italy; Oligocene, 11.6-5.3 Mya].

(3.) † In. primitiva (Radchenko & Dlussky, 2019). [m]. [Note 3]. Comb. nov.

Note 1. We erect the explicit catchall taxon † Incertogaster gen. nov., into which we place † In. aurora comb. nov., † In. praecursor comb. nov., and † In. primitiva comb. nov. We do so in order to recognize that these latter two species are not meaningfully placeable in Crematogaster based on their preserved morphologies, and that † In. aurora requires renewed attention. We choose † In. primitiva as the type species as the specimen of † In. praecursor examined by Emery is likely lost (see, e.g., Boudinot et al. 2016), and as the compression fossils require revised scrutiny and may be placeable in other genera, whether extant or extinct.

Note 2. † Crematogaster aurora is the oldest fossil attributed to the genus and is the most difficult to critique due to its highly suggestive but incomplete preservation. While we are uncertain about the placement of the fossil in Crematogaster due to the apparently axial postpetiolar helcium (i.e., located at about mid-height of AIV rather than atop AIV) and the unknown antennomere count, the specimen does indeed lack a vertically oriented petiolar node, at least as preserved. To prevent the use of this fossil for divergence dating analysis while the preserved anatomy is reevaluated, we transfer the species forming † In. aurora comb. nov. We hope that additional specimens may be found, or the known specimens are subjected to documentation using advanced techniques. One of the authors (BEB) examined both the type and the paratype of † In. aurora at the USNM and observed that the paratype differed substantially, having (possibly) antennal scrobes but more importantly a lateromedially narrow postpetiole that was anteriorly attached to abdominal segment IV (metasomal III). Additionally, this specimen possibly had a 2-3-merous antennal club. Altogether, this raises doubt about the attribution of the paratype to † In. aurora , which remains of uncertain identification at present.

Note 3. The amber-preserved males described by Emery as † In. praecursor comb. nov. and Radchenko & Dlussky as † In. primitiva comb. nov. are unlikely to be representatives of either the stem or crown of the genus Crematogaster and are incertae sedis in the Myrmicinae within † Incertogaster . Both specimens have 13-merous antennae, while all Crematogaster males examined by the lead author have antennae that are 10-12-merous ( Bolton 2003, p. 286; BEB, unpubl. data). Other diagnostic features include the short scape, which is ≤ 2 × the length of the pedicel, the pedicel shape, which is globular rather than cylindrical, and the mandibles, which are reduced or otherwise vestigial; the anterodorsal position of the postpetiolar helcium on abdominal segment IV can be difficult to discern. Unfortunately, Emery did not illustrate the wings or the face of † Cr. praecursor , so the fossil may need to be considered unidentifiable, hence subjectively invalid, if the specimen does not resurface. † Crematogaster primitiva , on the other hand, is well illustrated; its scapes are about 4 × the length of the pedicels, and the pedicels are not swollen or globular in shape. The mesosoma of this fossil (PMJ Pa 5824) is large and the mesoscutum is impressed, as in many Crematogaster , but the long and strongly nodiform petiole also contradict placement in that genus. At present, we cannot confidently attribute † Cr. primitiva to any valid generic taxon.