Spondioideae TAKHT.

Tiffney, Bruce H. & Manchester, Steven R., 2022, The Early Middle Eocene Wagon Bed Carpoflora Of Central Wyoming, U. S. A., Fossil Imprint 78 (1), pp. 51-79 : 63

Tribe Spondioideae TAKHT.

Genus et species indet.

Text-fig. 5g –i

M a t e r i a l. One fruit replaced by chalcedony, USNM

PAL 772358.

D e s c r i p t i o n. Endocarp subglobose, but wider below the equator than above, rounded-elliptical in transverse view, height 9.5 mm, diameter 11.7 mm × 12.3 mm. The base slightly rounded to flat, lacking any suggestion of an attachment point or ridges. The apical surface eroded and revealing seven locules, all but one represented by an elliptical pit. One locule covered by an apparent valve, but eroded such that further characters are lacking.

D i s c u s s i o n. This is clearly another fruit conforming to the Spondioideae . We recognize two Spondioid fruit types, cf. Pentoperculum MANCHESTER and cf. Pleiogynium in the Wagon Bed flora based on the current distinctions in the literature, and consider that USNM 772358 likely belongs to one of these. However, it is difficult to place with certainty due to its eroded condition. Another option would be to consider these all of the specimens as the product of one highly variable, parent plant, but with preservation limiting the appreciation of different characters (e.g., variable locule number, presence of a bipartite operculum versus a bipartite locule lining).

The Spondioideae include 20 genera and some 115 species of pantropical and subtropical trees, all with fleshy, animal dispersed, fruits. The systematics of the group has seen flux and is summarized by Mitchell et al. (2006). The Anacardiaceae are represented in the pollen flora of the Wagon Bed Formation ( Leopold and MacGinitie 1972) by Rhus L.

Figures

Text-fig. 5. Anacardiaceae (a–m), Burseraceae (n–q). Scale bars = 1cm. a–f: Pentoperculum sp. a–c: USNM PAL 772360. a: Lateral view of endocarp, apex up; three germination valves visible, the central clearly displaying the bipartite nature of the valve, reflected light, palladium coated. b: Apical view displaying six locules, with two preserved germination valves at the lower left, reflected light, palladium coated. c: Basal view of the endocarp, the locules suggested by swellings; note point of attachment, micro-CT scan surface rendering. d–f: Pentoperculum sp. USNM PAL 772359, reflected light, palladium coated. d: Lateral view of a probable 6-loculed endocarp, apex up; a single intact germination valve in the center, displaying the central lineation that divides it in two. e: Apical view; two bi-partite germination valves are visible, indicated by arrows to the middle cleavage line of two of the valves. f: Basal view, the locules suggested by the undulations in the margin. g–i: Indet. Spondioideae. USNM PAL 772358, reflected light, palladium coated. g: Lateral view of multi-locular endocarp, apex up. h: Apical view showing finely punctuate surface and peripheral locule cavities. i: Basal view. j–m: Cf. Pleiogynium USNM PAL 772357. j: Lateral view of the multi-locular endocarp, apex up; note intact germination valve on left and exposed locule facing the viewer, micro-CT scan surface rendering. k: Lateral view, rotated about 30° from (j), showing three exposed locules, reflected light, palladium coated; note bipartite locule lining at center. l: Apical view of the multilocular endocarp; the locule with intact germination valve at the upper right, reflected light, palladium coated. Arrows to each locule. m: Basal view showing central point of attachment and prominent radiating ridges aligned with the locules, micro-CT scan surface rendering. n–q: Canarium, USNM PAL 772361. Scale bar = 1cm. n: Lateral view of endocarp directly facing one germination valve flanked by two strong ridges; apex up; specimen coated in sodium nitrate and photographed by R. A. Scott. o: Lateral view facing one of the three pronounced ridges, flanked to the left and right by two germination valves; apex up. p: Apical view displaying the three strong ridges, arching over the apex and flanking three deep embayments, covered with germination valves. q: Basal view, the three ridges being less pronounced. o–q: Reflected light, palladium coated.