Eoceltis dilcheri Zavada and Crepet, 1981

Na, Yuling, Blanchard, Jane & Wang, Hongshan, 2019, Fruits, seeds and flowers from the Puryear clay pit (middle Eocene Cockfield Formation), western Tennessee, USA, Palaeontologia Electronica (a 49) 23 (3), pp. 1-57 : 14

Eoceltis dilcheri Zavada and Crepet, 1981

Figure 19

Description. Flowers up to 9 mm in diameter with perianth composed of four whorled tepals. Staminate flowers having up to 15 stamens with elongate anthers. Pollen triporate with lolongulate pores. Exine finely scabrate and perforate. Exine 1 µm in thickness, somewhat intermediate between granular and columellar, and occasionally with invaginations of the tectum (Zavada and Crepet, 1981, p. 931, figs. 7-13).

Number of specimens examined. 2. UF15816- 001356, 000455.

Remarks. Zavada and Crepet (1981) described seven specimens from the Lawrence clay pit and one specimen from the Puryear clay pit. Geographically, these two localities are 28 kilometers apart and chronostratigraphically, the Puryear locality is slightly older than the Lawrence locality ( Table 2). We are unable to locate the Puryear specimen reported by Zavada and Crepet (1981), which was presumably collected by David Dilcher and should be stored at the Florida Museum of Natural History. Two specimens, including the holotype, from the Lawrence clay pit are illustrated here to demonstrate the characters of this species.

Based upon floral and pollen features, including unisexuality of flowers, four tepaloid perianth parts in a whorl, type of pubescence, pollen type, and exine structures, Zavada and Crepet (1981) suggested that these flowers are related to the subfamily Celtidoideae of the Ulmaceae . When the stratification of exine of the fossil pollen is compared with that of the modern Celtis pollen, the alliance of the fossil with the Celtidoideae is apparent. Both have tectum perforated by more or less regular narrow channels and the same tectum thickness. However, they differ notably in that (1) the exine of the fossil pollen is closer to the truly tectate-columellate structure; (2) it has the greater number of columellae; (2) the columellae are formed by the fusion of granules; and (4) and the fossil pollen has invaginations in the tectum. The presence of invaginations in the tectum is only observed in the pollen of the Tiliaceae and the Dipterocarpaceae .

We agree with Zavada and Crepet (1981) and assign these fossil flowers to the Ulmaceae .

Figures

FIGURE 19. Eoceltis dilcheri Zavada and Crepet, 1981: 1) 15816-001356, specimen showing two flowers each with three tepals. Note filaments (f) and dense, simple trichomes (t). Scale bar equals 1 mm; 2) UF15816- 000455, showing a flower with four tepals covered with dense, simple trichomes (t). Scale bar equals 1 mm.