Bonanzacarpum sprungerorum, Manchester & Lott, 2019

Manchester, Steven R. & Lott, Terry A., 2019, Bonanzacarpum Sprungerorum Sp. Nov. - A Bizarre Fruit From The Eocene Green River Formation In Utah, Usa, Fossil Imprint 75 (2), pp. 281-288 : 283

Bonanzacarpum sprungerorum sp. nov.

Text-figs 1–3

H o l o t y p e. UF 18054-55045 ( Text-fig. 1a, b ) housed in Florida Museum of Natural History.

P a r a t y p e s. UCMP PB02016-201239, UCMP PB02016-201240, UF 15753-78205, UF 18054-22886, 55045, 55055.

P l a n t F o s s i l N a m e s R e g i s t r y N u m b e r.

PFN000564 (for new species).

E t y m o l o g y. The species name honors Mike and Sandra Sprunger who collected and donated some of the finest examples.

T y p e l o c a l i t y. Vicinity of Bonanza , Utah, USA

( UF locality 18054: 39°53′40.76″ N, 109°8′42.31″ W) .

T y p e h o r i z o n a n d a g e. The Parachute Creek

Member, early to middle Eocene, ca. 47 Ma.

D i a g n o s i s. Fruit a tabular, button-shaped circumscissile capsule, rounded-polygonal in transverse section with 4 to 6 equal to unequal sides. Capsule unilocular, circumscissile with an apical operculum closely fitting like a stopper. Lateral walls smooth, straight. Basal surface of locule with 7–11 smooth, obpyriform, slightly raised areas radiating from a central point. Obpyriform areas pointed proximally, with somewhat convex lateral margins and round distal margins. Obpyriform areas with corresponding cycle of smaller indentations on the basal external surface.

D e s c r i p t i o n. Fruits tabular, button-shaped circumscissile capsules 2–4 mm high and 18–30 mm in diameter, rounded-polygonal in transverse section with 4 to 6 equal to unequal sides. Capsule unilocular, circumscissile with an apical operculum closely conforming in shape and size to that of the fruit as viewed transversely, and closely fitting like a stopper. Lateral walls smooth, straight. Basal surface of locule with 7–11 smooth, obpyriform, slightly raised areas radiating from a central point. Obpyriform areas are pointed proximally, with somewhat convex lateral margins and round distal margins, 7–9 mm long, and 1.3– 3.0 mm wide. These marks are not evident from the outer surface of the fruit, but a corresponding cycle of smaller indentations occurs on the basal external surface. Fruit wall 1.2–1.6 mm thick, composed of sclerenchymatous tissue.

Figures

Text-fig. 1. Bonanzacarpum sprungerorum gen. et sp. nov., fruits. a, b) Mold of inner surface of the basal portion of a fruit with 11 radiating placentae, holotype, UF 18054-55045. a) Transverse view, reflected light. b) Oblique lateral view showing domed appearance and recessed placentae, surface rendering from micro-CT scan data. c) Transversely compressed pentagonal specimen, reflected light, UF 18118-22840. d–f) Mold of basal portion of a fruit with 7 radiating placentae, UCMP PB02016-201240. d) Transverse view, reflected light. e, f) Surface renderings of same specimen as viewed through the shale from behind, showing sharp edge of the surrounding wall from which the operculum is inferred to have been shed. Specimen rotated with two views: nearly transverse and oblique-lateral, showing placentae slightly raised within the locule. g–j) Upper and lower counterpart surfaces of the basal portion of a fruit, UCMP PB02016-201239. g) Reflected light of locule cast of basal portion of fruit. h) Reflected light image of the counterpart from (g), representing the basal endocarp surface. i, j) Micro-CT surface rendering of the specimen in (g, h), showing short, button-shaped outline, and open apex interpreted to indicate that it is dehiscent with the operculum and

Text-fig. 2. Bonanzacarpum sprungerorum gen. et sp. nov., fruits. a–d) UF 18054-62091. a) Compressed quadrangular fruit with coalified remains of endocarp, reflected light microscopy. b) Same specimen by micro-CT scan, volume rendering with coalified material rendered partly translucent showing radiating placental ridges. c) Same specimen, isosurface generated from micro-CT scan data, showing smooth apical surface. d) Same viewed laterally showing relatively short side walls of the fruit. e–k) UF 18054- 55050. Pentagonal fruit. e) Impression of apical surface by reflected light. f) Counterpart impression of same specimen by reflected light, showing central collapsed portion of wall, and thick lateral walls. g) Surface rendering from micro-CT data. Oblique-lateral view of apical surface showing straight side walls and marginal fissure defining the operculum. h) Digital longitudinal section through the complete specimens (both counterparts assembled), with black area representing the space originally occupied by the fruit. Note the width much greater than height. i) Transverse view of the apical surface from (e). j) Depth mapping of the complete specimen, showing whorl of 8 depressions on lower surface. k) Oblique view of surface rendering representing the basal side of the fruit, with evident collapse of some of the basal wall. l) Hexagonal fruit by reflected light, with obvious stress fractures, and central whorl of depressions, UF 18054-55053. m) Transverse view of locule cast with coalified remains of endocarp at lower margin, UF 18054-55046. n) Largest specimen, UCMP PB02016-391009. Scale bar in (m) = 10 mm, applies to (a–l, n).

Text-fig. 3. Bonanzacarpum sprungerorum gen. et sp. nov., fruits. a) Apical view of UF 18054-55050, showing the peripheral crack (arrows) delineating the apical operculum. Isosurface rendering from micro-CT scan data. b–g) UF 18054-55051. b) Viewing toward the apex, impression containing coalified remains of the endocarp. c) Counterpart specimen, viewed toward the base, impression with subsidence cracks of the endocarp. d, e) Isosurface rendering from micro-CT scan of the specimen in (b, c). Note the clear delineation of operculum in (d) (arrows) and subsidence cracks in (e). f) Digital longitudinal section with arrows indicating the margin of operculum. g) Surface rendering in longitudinal section with arrows indicating margin of operculum. h) Rounded pentangular fruit with convex surface of the base of the locule, DMNH 22486, loc. 323. i) UF 18054-55054, reflected light of concave basal impression with adherent coalified material. j) Surface rendering of specimen in (i), based on micro-CT scan data, showing straight lateral walls and domed base. Scale bar in (a), (b) = 10 mm, bar in (b) applies also to (c–j).