Portnallia bognorensis M. CHANDLER , 1961

Manchester, Steven R. & Collinson, Margaret E., 2022, Mastixioid Fruits (Cornales) From The Early Eocene London Clay Flora: Morphology, Anatomy And Nomenclatural Revision, Fossil Imprint 78 (1), pp. 310-328 : 321

Portnallia bognorensis M. CHANDLER, 1961

Text-fig. 9a–o

1961 Portnallia bognorensis M.CHANDLER , p. 285, pl. 28, figs 39–44 (V. 30422 b).

1961 Portnallia sheppeyensis M.CHANDLER , p. 286, pl. 28, figs 45, 46, pl. 29, figs 1–3.

1986 Beckettia bognorensis (M.CHANDLER) ERW.KNOBLOCH et MAI , p. 107.

1986 Beckettia sheppeyensis (M.CHANDLER) ERW.KNOBLOCH et MAI , p. 107.

H o l o t y p e. V.30421 (Natural History Museum,

London).

R e m a r k s. The genus Portnallia was established by Chandler (1961) for subglobular to ovoid 2- to 3- to 4-locular endocarps distinguished by their smaller size (4–6 mm long) relative to Exbeckettia (13–15 mm long) and Lanfrancia (12 mm long). Chandler recognized two species, differing from each other in size (3.5–6 mm long in P. bognorensis , vs. 6–7.5 mm in P. sheppeyensis ), but she added “Should more abundant material become available in the future, the validity of Portnallia sheppeyensis as a species should be reviewed…” ( Chandler 1961: 287). Transverse sections of the two species show striking similarities in form of the locule and the narrow fibrous intervening septae ( Text-fig. 9b, e, g, i, m–o ). Knobloch and Mai (1986) treated both species of this genus as conspecific and transferred them to Beckettia . However, as mentioned above, the name Beckettia was earlier established for a genus of moss, so the name with priority in the case of a merger of these genera would be Portnallia . However, we do not support the merger of these genera, because the fruit stones of Exbeckettia are characterized by large areas of isodiametric cells between adjacent locules, whereas those of Portnallia are composed mainly of fibres. We retain Portnallia as a distinct entity from Lanfrancia because of its much smaller size (about half the length).

Figures

Text-fig. 9. Portnallia. a–j: P. bognorensis M.CHANDLER. a–g: Holotype, V. 30421. a: Oblique lateral view with dorsal surface of locule cast facing towards right side. b: Basal view (original illustration from pl. 28, fig. 40 of Chandler 1961). c–g: Micro CT data. c–f: Surface renderings. c: Lateral view with interlocular septum facing forward. d: lateral view with dorsal surface of locule facing forward. e: Basal view. f: Apical view. g: Digital transverse section near equatorial position showing (c) to u-shaped locules. h: Apical view of tetralocular fruit, V. 30423 (original illustration from pl. 28, fig. 42 of Chandler 1961). i: Transverse section of specimen in (h), reflected light. j–o: P. sheppeyensis M.CHANDLER, Holotype V. 30428, here synomomized with P. bognorensis, from micro-CT data. j–m: Surface renderings. j: Lateral view with interlocular septum facing forward. k: Lateral view with dorsal surface of locule facing forward. l: Basal view. m: Apical view. n: Digital equatorial transverse section showing the three preserved locules and extensive cracking due to pyrite decomposition. o: Translucent volume rendering, apical view showing (c) to u-shaped locules. Scale bars 2 mm, bar in (a) applies also to (b), bar in (e) applies to also to (c, d), bar in (g) applies also to (f), bar in (j) applies to applies also to (k–m).