identifier	taxonID	type	CVterm	format	language	title	description	additionalInformationURL	UsageTerms	rights	Owner	contributor	creator	bibliographicCitation
03BA87A8FFD6FFC4FCC250F9FD31FD38.text	03BA87A8FFD6FFC4FCC250F9FD31FD38.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Cariridris bipetiolata Brandao & Martins-Neto 1989	<div><p>Results and Discussion</p><p>Knowledge of the fossil record of ants and their allied lineages (ie Formicoidea) has expanded considerably since the original description of † Cariridris . For instance, hell ants († Haidomyrmecinae) were first discovered shortly thereafter (Dlussky 1996), and several taxa bridging crown ants and their wasp relatives have since been described (Nel et al. 2004, Barden and Grimaldi 2016, Boudinot et al. 2020, Zhuang et al. 2025). These discoveries, allied to in-depth comparative morphological studies, have significatively impacted the taxonomic and morphological boundaries of Formicoidea (Boudinot et al. 2020, Oberski et al. 2025). Parallel advances in the comparative anatomy of extant and fossil Apoidea have also enhanced our understanding of apoid wasp diversity and definition (Antropov 2000, Rosa and Melo 2023). Considering these advances and based on our tomographic reanalysis of † Cariridris, we reaffirm its identity as an ant, as discussed below.</p><p>The holotype is preserved as a frontal section, with only the dorsal portion of the body known, limiting initial interpretation to its internal dorsal view (Fig. 1A). Reconstructions revealed additional structures, such as the dorsal surface of the mesosoma and metasoma, and most of the left hind leg (Fig. 2A). Notably, portions of the specimen interpreted as hidden by matrix by Grimaldi et al. (1997) were, in fact, not preserved. Despite a certain degree of deformation, the portion of the specimen embedded in the matrix preserves a considerable level of 3-dimensional integrity.</p><p>The antennal socket is situated on a frontal projection anterior to the compound eye (Figs 1B and 2B). A similar configuration is also observed in † Vulcanidris and † Aquilomyrmex, extinct genera with distinctly produced clypeus and frons displacing the antennal socket anterad (Perrichot et al. 2020, Lepeco et al. 2025). Additionally, the antennal socket is oriented laterally, a key synapomorphy of Formicidae (Richter et al. 2022) . The 2 elongated scapes are present, articulating obliquely with the curved and pedunculate pedicels distally (Fig. 1B). The general form and angle of this articulation are suggestive of a geniculate antenna, a characteristic of both extant and extinct ants (Boudinot 2015, Richter et al. 2022). In contrast, extant and fossil Ampulicidae typically display a much shorter scape, often less than half the head length (Antropov 2000), while in † Cariridris the scape is nearly as long as the head length.</p><p>Although the pronotum is fragmentary, the preserved portion is visible nearly touching the left tegula (Fig. 2D), inconsistent with the apoidean condition where the dorsolateral region of the sclerite is reduced and distant from the tegula, forming a lateralized lobe (Rosa and Melo 2023). The mesoscutum exhibits a faint indication of an oblique notaulus (Fig. 2D) and is separated from the scutellum by a deep, arched scutoscutellar sulcus. The propodeal spiracle is positioned laterally and widely separated from the metanotum (Fig. 2C and D), a configuration characteristic of Formicidae (Boudinot 2015) and commonly observed in Cretaceous ants (Dlussky 1996, Grimaldi et al. 1997, Barden and Grimaldi 2012, 2016, Zhuang et al. 2022). In contrast, Ampulicidae have a more dorsally positioned spiracle, close to the metanotum, and a squared, elongated propodeum.</p><p>Surprisingly, the right forewing is partially preserved (Fig. 1A), confirming that the specimen is not a wingless worker. Nevertheless, the absence of a wingless caste in early ant lineages remains plausible, as wingless individuals are rare or unknown in several extinct genera such as † Aquilomyrmex, † Chonidris, and † Dhagnathos (Barden and Grimaldi 2012, Barden et al. 2020, Perrichot et al. 2020, see Boudinot et al. 2022 for an overview). This pattern may reflect either biological absence or preservation bias. Therefore, the possibility of eusociality in † Cariridris cannot be excluded, though further evidence is needed. Wing venation in the fossil is fragmentary, with only veins Sc+R, M+Cu, 1A, 1cu-a, and the distal portion of Rs preserved, but not of taxonomic relevance. Recently described fossils indicate that complex venation is not exclusive to Apoidea and other aculeate lineages, but also present in various early Formicidae (Barden and Grimaldi 2016, Boudinot et al. 2020, Perrichot et al. 2020, Lepeco et al. 2025). Therefore, if the specimens mentioned by Verhaagh (1996) are conspecific with † Cariridris bipetiolata, their observed wing venation alone would not preclude their position within Formicidae .</p><p>Metasomal terga I–IV are preserved, revealing clearly ant-like features. The first tergum has similar anterior and posterior diameters and forms a distinct dorsal node with a slanted posterior surface (Fig. 2E and F). The second tergum is strongly constricted where it articulates with the third (Fig. 1C), which is the longest, as observed in many Cretaceous ants (Barden and Grimaldi 2012, 2016, Cao et al. 2020). In Ampulicidae, the second metasomal tergum is invariably the longest, and the first is extremely narrow anteriorly, widening posteriorly. No ampulicid shows a third tergum with a strong constriction or elongation, either in extant or fossil representatives (Antropov 2000), further distancing † Cariridris from Apoidea.</p><p>Taken together, the similarities between † Cariridris and Ampulicidae are unsupported by diagnostic features. In addition, † Cariridris shares key morphological traits with Cretaceous ants, particularly the Aptian † Vulcanidris . These include a long, slender scape positioned on a frontal shelf; long and proximally bulbous femora (Fig. 1A); first and second metasomal segments posteriorly constricted, and an enlarged third segment. Therefore, † Cariridris is currently best placed within † Haidomyrmecinae considering the available data, reframing its initially suggested affinity with Myrmeciinae . The latter subfamily diverged from Pseudomyrmecinae in the Upper Cretaceous (Borowiec et al. 2025), having fossil representatives dating to the Paleocene (Jouault and Nel 2022). Still, inclusion of † Cariridris in † Haidomyrmecinae remains tentative, and may be re-evaluated in the future based on the study of additional specimens.</p><p>The large compound eye of the holotype is reminiscent of male ants, raising the possibility that it could represent a male of † Vulcanidris . However, the specimen exhibits a widened gaster with a posterior sheat-like structure, likely part of the sting apparatus (Fig. 1C). Direct comparison with Cretaceous ants suggests insufficient abdominal space for 3 additional segments within the silhouette in the matrix, as would be expected in males (Fig. 1C). In addition, the frontal projection indicates specialized predatory structures (see Barden et al. 2020), which are unlikely to be present in males, whose morphology in † Haidomyrmecinae remains unknown. Still, the holotype specimen of † Cariridris differs from † Vulcanidris in its smaller size, proportionally larger eyes (colored in blue in Fig. 3b–d of Lepeco et al. 2025), narrower gena, antennal socket closer to the eye, and by having femora apparently more bulbous proximally. Though incipient, these differences should be considered in light of additional material in the future in order to validate both genera. Given the available information, we consider that synonymizing the 2 genera would be premature.</p><p>In light of new evidence presented here, † Cariridris bipetiolata can no longer be confidently placed outside Formicidae . Our reanalysis reveals a combination of key ant synapomorphies, particularly in the antenna, mesosoma, and metasoma, supporting its inclusion within the family, and most likely within † Haidomyrmecinae . This reevaluation reinstates † Cariridris as one of the earliest known ants, adding to the knowledge about the paleobiogeographic and ecologic range of early Formicidae in Gondwana. Future work should focus on locating, preparing, and analyzing other specimens tentatively attributed to † Cariridris, as well as broader surveys of fossil insect diversity in Cretaceous Gondwanan strata, to refine our understanding of ant origins and early evolution.</p></div>	https://treatment.plazi.org/id/03BA87A8FFD6FFC4FCC250F9FD31FD38	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Lepeco, Anderson;Camacho, Gabriela P;Meira, Odair M;Matielo, Diego M;Brandão, Carlos R F	Lepeco, Anderson, Camacho, Gabriela P, Meira, Odair M, Matielo, Diego M, Brandão, Carlos R F (2026): Revisiting the identity of the enigmatic † Cariridris bipetiolata (Hymenoptera: Aculeata) using micro-computed tomography. Insect Systematics and Diversity 10 (3): 1-6, DOI: 10.1093/isd/ixag024, URL: https://doi.org/10.1093/isd/ixag024
