Pheidole cordata

†Pheidole cordata Temporal range: East African copal
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Attini
Genus:	Pheidole
Species:	†P. cordata
Binomial name
†Pheidole cordata (Holl, 1829)

Identification

The species, represented by the major worker, is identifiable as a member of the Pheidole megacephala species group by (1) the presence of the conspicuous ventral convexity of the postpetiolar sternum (Fig. 19A; e.g., Salata and Fisher 2020). It differs from Pheidole megacephala, Pheidole megatron and Pheidole spinosa by (2) the well-developed inner hypostomal teeth (Fig. 20B; e.g., Salata and Fisher 2022). Among the megacephala group species more broadly (e.g., Fischer et al. 2012), it differs in having (3) facial rugosity that extends to the posterior margin of the occipital lobes (Fig. 20A, note: among type specimens of the group imaged on AntWeb, this condition also occurring in Pheidole megacephala impressifrons, which has a more angular bulge of the postpetiolar sternum). See the description below for further conditions.

Distribution

The neotype of this taxon is from East African copal.

Photo Gallery

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  Boudinot et al. (2024), Figure 19. A–D. 3D-reconstruction of the neotype of ‡Pheidole cordata. A. Habitus in lateral view; B. Habitus in frontal view; C. Habitus in dorsal view; D. Habitus in ventral view. Abbreviation: ppd = propodeum.
• 

  Boudinot et al. (2024), Figure 20. A–D. 3D-reconstruction of the neotype of ‡Pheidole cordata preserved in piece PMJ Pa 5889. A. Details of head in frontal view, arrow indicates occipital lobe; B. Detail of mouthparts in ventral view; C. Details of foreleg in lateral view; D. Details of metasoma in dorsolateral view. Abbreviations: IHT = inner hypostomal tooth, OHT = outer hypostomal tooth.
• 

  Boudinot et al. (2024), Figure 21. A, C, E. Copper lithographs by Schweigger (1819), which Holl (1829) named †Formica cordata. B, D, F. Photographs of the neotype of ‡Pheidole cordata. A. Overview of the amber piece; B. Overview of the amber piece, arrow indicates the inclusion; C. Habitus in lateral view; D. Habitus in ventrolateral view; E. Habitus in dorsal view; F. Habitus in dorsolateral view.

Boudinot et al. (2024), Figure A5 - Model 5 of the neotype of ‡Pheidole cordata preserved in copal piece PMJ Pa 5889.

Nomenclature

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

• †cordata. †Formica cordata Holl, 1829: 140 (s.) East African copal.
  • [Notes (i): this ant is cited and figured in Schweigger, 1819: 119, pl. 18, fig. 70, but is not named; (ii) neotype designated by Boudinot, in Boudinot, Bock, et al. 2024: 148.]
  • Combination in Pheidole: Mayr, 1868b: 17.
  • Status as species: Scudder, 1891: 699; Dalla Torre, 1893: 194; Bolton, 1995b: 319.
  • Incertae sedis in Myrmicinae: Casadei-Ferreira, et al. 2019: 123 (in text).

Type Material

• Neotype. PMJ Pa 5889, designated by Boudinot et al., 2024: 148. Figs 19A–D, 20A–D, 21B, D, F. Locality and horizon: East African copal (IAA results

for PMJ Pa 5889: copal (Table 1); 14C- dating for PMJ Pa 5889: ~700 years old).

Taxonomic Notes

Casadei-Ferreira, Chaul & Feitosa, 2019: Among the extinct species of Pheidole, the most dubious fossil is †P. cordata. Its first record in the literature is Schweigger (1819). In this work, the author listed fossils from Baltic amber and described informally and illustrated an ant with a remarkably large head, showing triangular projections on the propodeum. These projections can be interpreted as propodeal spines or teeth. However, Schweigger did not name this specimen, and some years later, Holl (1829: 140) named it as †Formica cordata, using the same characters as Schweigger.

Mayr (1868) transferred it to Pheidole (Mayr 1868), even though he believed that Schweigger’s sketch was not clear and Holl’s description was somewhat crude. We conclude that Holl’s decision to describe this species and Mayr’s placement in Pheidole may have been hasty. The specimen studied by Schweigger is presumably lost, which precludes its proper placement using current genus concepts in Formicidae (Mayr 1868; Antweb 2019). Dlussky (2008) suggested treating †Formica cordata as Formicidae incertae sedis, and we concur that there is no strong reason to assume it belongs to Pheidole, though it is certainly a myrmicine ant. Thus, we consider †P. cordata as incertae sedis in Myrmicinae.

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).
• Casadei-Ferreira, A., Chaul, J.C.M., Feitosa, R.M. 2019. A new species of Pheidole (Formicidae, Myrmicinae) from Dominican amber with a review of the fossil records for the genus. ZooKeys 866: 117–125 (DOI 10.3897/zookeys.866.35756).
• Holl, F. 1829. Handbuch der Petrefactenkunde. Bd. 2 [part]. Dresden: P. O. Hilschersche Buchhandlung, pp. 117-232. (page 140, soldier described)
• Mayr, G. 1868c. Die Ameisen des baltischen Bernsteins. Beitr. Naturkd. Preuss. 1: 1-102 (page 17, Combination in Pheidole)
• Schweigger, A.F. 1819. Beobachtungen auf naturhistorischen Reisen. Anatomisch-physiologische Untersuchungen über Corallen; nebst einem Anhange, Bemerkungen über den Bernstein enthaltend. Berlin: Reimer, 127 pp. (page 119, see also)
• Wang, W.Y., Soh, E.J.Y., Yong, G.W.J., Wong, M.K.L., Benoit Guénard, Economo, E.P., Yamane, S. 2022. Remarkable diversity in a little red dot: a comprehensive checklist of known ant species in Singapore (Hymenoptera: Formicidae) with notes on ecology and taxonomy. Asian Myrmecology 15: e015006 (doi:10.20362/am.015006).