Palaeosminthurus juliae

†Palaeosminthurus juliae Temporal range: Burdigalian to Langhian, Early to Middle Miocene PreЄ Є O S D C P T J K Pg N Barstow Formation, California, United States
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Formicinae
Genus:	Palaeosminthurus
Species:	†P. juliae
Binomial name
†Palaeosminthurus juliae Pierce & Gibron, 1962

Boudinot et al. (2024), Note 8 - †Palaeosminthurus juliae is represented by a single male that was phosphatized in a calcareous nodule in the Calico member of the Miocene-aged Barstow formation in the Mojave Desert of California. The taxonomic history of this fossil is unusual. In its original description in Pierce and Gibron (1962), the fossil was classified as a new species of a new genus representing a new family of symphypleonan Collembola: †Palaeosminthurus juliae (†Palaeosminthuridae). These names went unnoticed for more than two decades, until the collembolist Dr Judith Najt (see Deharveng et al. 2017) observed that the preserved head, scape, thorax, and leg remnants of the fossil belong to a hymenopteran, which she identified as Camponotus (see Najt 1987). Subsequently, Roy R. Snelling examined the fossil, presumably at the Los Angeles County Museum, and concluded that the taxon is a junior synonym of Camponotus festinatus (Snelling 2006), an identification that was communicated to Barry Bolton in 2004 but went unpublished by the time of Roy Snelling’s death in 2008. Bolton provisionally accepted this hypothesis in his taxonomic catalog (Bolton 2023). Here, after critical consideration of the available morphological evidence, we exclude the species from Camponotus, and revive the genus †Palaeosminthurus, which we consider to be incertae sedis in Formicinae and unidentifiable hence invalid. Specifically, we attempted to run the specimen through the male-based key to all Nearctic genera of Smith (1943) and that of Boudinot for all New World formicine genera (see section 3.7.H of Boudinot 2020); there is simply too little structural detail preserved to render a meaningful identification of this fossil. Unless a method like laminar µ-CT may be applied successfully, we anticipate that this fossil will remain unidentifiable at the genus and tribal levels among the Formicinae.

Distribution

This taxon was described from Barstow Formation, California, United States (Burdigalian to Langhian, Early to Middle Miocene).

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

• juliae. †Palaeosminthurus juliae Pierce, W.D. & Gibron, 1962: 147, fig. 4 (m.) U.S.A. (California, Miocene).
  • [Note: originally described in Order Collembola, Family †Palaeosminthuridae.]
  • Transferred to Formicidae: Najt, 1987: 152.
  • Status as species: Bolton, 1995b: 311.
  • [Note: junior synonym of Camponotus festinatus (Buckley): Snelling, R.R. (pers. comm. to B. Bolton, 2004). Synonymy remained unpublished at his death in 2008; unconfirmed but accepted provisionally here (Bolton, 1995b: 311).]
  • Unidentifiable taxon: Boudinot, in Boudinot, Bock, et al. 2024: 144.

Type Material

• Holotype, male, Calico Mountains, San Bernardino County, California, 735m, United States, 34.94°N 116.83°W / 34.94; -116.83, John Gibron, Los Angeles County Museum of Natural History; silicaceous nodule.

References

• Boudinot, B.E., Bock, B.L., Weingardt, M., Tröger, D., Batelka, J., LI, D., Richter, A., Pohl, H., Moosdorf, O.T.D., Jandausch, K., Hammel, J.U., Beutel, R. G. 2024. Et latet et lucet: Discoveries from the Phyletisches Museum amber and copal collection in Jena, Germany. Deutsche Entomologische Zeitschrift 711, 111–176 (doi:10.3897/dez.71.112433).
• Najt, J. 1987. Le Collembole fossile Palaeosminthurus juliae est un Hyménoptère. Rev. Fr. Entomol. (Nouv. Sér.) 9: 152-154.
• Pierce, W.D., Gibron, J. 1962. Fossil arthropods of California. 24. Some unusual fossil arthropods from the Calico Mountains nodules. Bulletin of the Southern California Academy of Sciences 61: 143-151..