Petracloeon carolinensis Sroka & Gattolliat, 2025, sp. nov.
Creators: name: Sroka, Pavel
name: Gattolliat, Jean-Luc
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Ephemeroptera
Baetidae
Petracloeon
Petracloeon carolinensis

description: Petracloeon carolinensis sp. nov.
Figs 1–12, 13–20
Diagnosis (female imago).
Small size (body length approximately 1.9 mm); forewing with single marginal intercalary veins poorly expressed (Figs 14, 15); pronounced angle on posterior margin of forewing between CuA and CuP (Figs 15–17); hind wing with small basally positioned costal process (Figs 18, 19); first (most anterior) longitudinal vein of hind wing sigmoidal, second vein bifurcated, with intercalary vein also bifurcated and followed by another simple intercalary vein (Figs 18, 19).
Etymology.
The specific epithet refers to the geographic location of the amber deposit in North Carolina.
Holotype.
AMNH NC-VK 261, deposited in AMNH.
Description.
Body length 1.9 mm. Observable from dorsal and ventral aspect (Figs 1, 2). The specimen represents a female (based on compound eyes not distinctly enlarged, forelegs not elongated and no traces of male genitalia).
Head: length 0.25 mm, width 0.45 mm. Compound eyes not divided (Fig. 3), diameter 0.21 mm. Distance between compound eyes approximately equal to eye diameter. Three fully developed ocelli of same size. Antennae filiform, 0.55 mm long (approximately 2 × head length), scapus slightly shorter than pedicellus, antennal flagellum 0.43 mm long.
Thorax: thoracic terga and sutures mostly visible from dorsal view (Figs 4, 5). Mesonotal suture (MNs) absent. Sublateroscutal suture (SLSs) present. Thoracic sterna partially visible from ventral view (Figs 11, 12). Furcasternal protuberances widely separated. All legs of same general arrangement, with femora of similar size, 0.4 mm long and tibio-patellar suture present (Figs 6, 7). Foreleg with tibia and tarsus combined 0.6 mm long (delimitation of basal tarsal segments not clearly visible). Claws of all legs dissimilar (first oval and blunt, second hooked and pointed). Individual tarsal segments best observable in left hind leg (Figs 9, 10). Hind tarsus four-segmented, 0.20 mm long, first basal segment fused with tibia, three segments movable. Length of first and second segment combined 0.11 mm (exact location of articulation between first and second segment obscured), third and fourth segment approximately equal in length, and each 0.06 mm long. Both forewings preserved (Figs 1, 2, 13, 15–17), right forewing folded over, left forewing with apical portion missing and slightly distorted anterior margin distally (Figs 16, 17). Forewing 2 mm long (approximately equal to body length), 0.85 mm wide, with pronounced angle on posterior margin between CuA and CuP. Pterostigma of right forewing with three simple faintly visible crossveins. In remaining sectors of forewing, very scarce crossveins. MA 2 free, not connected with MA 1. CuP curved backwards near its base. Cubital field of forewing with intercalary veins, not connected to CuA. Single free marginal intercalary veins on posterior margin present, inconspicuous, well-distinguishable only in median sector of left forewing (Figs 14, 15, 17). Right hind wing poorly visible, folded alongside body. Left hind wing well visible (Figs 13, 18–20), 0.63 mm long, 0.29 mm wide (approximately 0.3 × forewing length). Small acute costal process positioned basally. Three principal longitudinal veins; first anterior vein sigmoidal, approaching costal margin distally from costal process. Second longitudinal vein bifurcated; intercalary vein positioned between its branches also distally bifurcated and followed by another simple intercalary vein (Figs 18, 19). Bifurcations in this wing sector possibly originating from fusions of basal portions of originally separate veins. Third, most posterior principal longitudinal vein simple, reaching posterior wing margin. Further two separate short veins located more posteriorly (Figs 19, 20). Single crossvein visible in costal field, in approximately 1 / 3 of wing length (Figs 19, 20).
Abdomen: no colour pattern preserved on terga or sterna, distal part of abdomen damaged (Fig. 8). Cerci covered with short hair-like setae. Length of cerci unknown, only basal portions (approximately 2 mm long) preserved. Paracercus vestigial (Fig. 8).
description: Published as part of Sroka, Pavel & Gattolliat, Jean-Luc, 2025, The first mayfly (Ephemeroptera, Baetidae) from Late Cretaceous amber of North Carolina, USA, pp. 125-132 in Fossil Record 28 (1) on pages 125-132, DOI: 10.3897/fr.28.e143974