Ibericarpus cuneiformis E.M.FRIIS, P.R.CRANE, K.R.PEDERSEN, M.M.MENDES et J.KVAČEK, 2022

Friis, Else Marie, Crane, Peter R., Pedersen, Kaj Raunsgaard, Mendes, Mário Miguel & Kvaček, Jiří, 2022, The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms, Fossil Imprint 78 (2), pp. 341-424 : 373-374

Ibericarpus cuneiformis E.M.FRIIS, P.R.CRANE, K.R.PEDERSEN, M.M.MENDES et J.KVAČEK sp. nov.

Text-figs 21–23

Holotype. S115851 (Catefica sample 49; figured Text-fig. 21a–c ).

Plant Fossil Names Registry Number.

PFN002791 (for new species).

Paratypes. S115852–S115856, S118683–S118685, S265996, S266012 (Catefica sample 49), S170413– S170417, S174907, S266037, S266135 (Catefica sample 50); P0477 (Catefica sample MM75).

Repository. Holotype: Palaeobotanical Collections , Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden ( S).

Paratypes: Palaeobotanical Collections, Department of Palaeobiology, Swedish Museum of Natural History , Stockholm, Sweden ( S) and Geological Museum of Lisbon, Lisbon, Portugal ( P) .

Etymology. From the wedge-shaped fruits.

Type locality. Catefica (39° 03ʹ 30ʺ N; 09°14ʹ 30ʺ W), between the villages of Catefica and Mugideira, about 4 km south of Torres Vedras, Portugal .

Type stratum and age. Almargem Formation, Early Cretaceous (Aptian-early Albian).

Specific diagnosis.As for the genus.

Dimensions. Carpel bearing axis up to about 1.7 mm long and 1.1 mm in diameter; individual carpels up to 1.05 mm long and 0.4 mm broad.

Description and remarks. The species is known from two pistillate structures bearing carpels (Textfigs 21a–c, 22a, b) as well as detached fruits that occur either isolated ( Text-fig. 22c ) or in groups ( Text-figs 22d , 23a–c ). One group of detached fruits (S174907; Text-fig. 22d ) was studied for internal details using SRXTM.

The holotype consists of a central axis with numerous carpels borne in a spiral arrangement ( Text-fig. 21a–c ). Although the specimen has lost some of its carpels the total original number is estimated to have been about 70, based on those still attached to the axis and the scars from the detached carpels. This specimen was probably preserved early in development before the carpels were shed. Another carpel-bearing specimen is thought to be at fruiting stage and the few carpels still attached to the axis when it was recovered were only loosely attached and fell off as the axis was mounted for SEM ( Text-fig. 22a, b ). The infructescence axis of this second specimen is about 1.9 mm long and based on the scars on the axis, there were about 70 carpels as also in the holotype. The diameter of the axis (ca. 0.3 mm) is more or less uniform from base to apex (Textfig. 22a). There are no traces of other floral organs or bracts associated with the individual carpels or with the carpelbearing axis. Specifically, there is no distinct joint between the infructescence stalk and the portion of the inflorescence axis that has the carpel scars. There are also no scars from bracts, perianth parts or stamens associated with the carpel scars.

The carpels are densely spaced on the axis. Each carpel is about 0.35 mm long and 0.25 mm wide, with the carpels of the second specimen ( Text-fig. 22 ) larger than those of the holotype. Carpels are obconical to pyriform in lateral view, and angular in transverse section as a result of their dense packing on the axis. Each carpel contains a single ovate ovule/seed with micropyle pointing towards the base and in one specimen with remains of embryo preserved (Textfig. 23a–c).

The epidermis of the carpel wall consists of small, bulging, isodiametric cells covered by a thick cuticle (Textfigs 21a, 22b–d, 23a–c). The cell outlines are particularly distinct in the protected regions where adjacent carpels meet, but less so in the apical portion of the carpel that is free ( Text-figs 21c , 22b–d ). The stigmatic area of each carpel is seen as a small apical swelling ( Text-figs 21c , 22b–d ).

No pollen grains have been observed in the stigmatic region or on other parts of the structure.

Affinity and other occurrences. For comments on the possible relationships of Ibericarpus see comments on the genus (above). Ibericarpus cuneiformis is common in the Catefica mesofossil flora, where it is characteristic for the basalmost layers of the outcrop. There are also fruitlets of Ibericarpus cuneiformis in the Buarcos mesofossil flora.

Figures

Text-fig. 21. Scanning electron microscope (SEM) images of Ibericarpus cuneiformis gen. et sp. nov.; Catefica locality, Portugal. a) Fruiting structure in lateral view showing numerous small, helically arranged wedge-shaped fruitlets each with a slightly differentiated apical stigmatic region (st); no bracts or scars from bracts, perianth or stamens were observed associated with the entire structure or with individual carpels; b) Apical portions of fruitlets showing differentiation of the stigmatic region (st); c) Detail of apical portion of fruitlet showing slightly raised stigmatic region (st) and possible ventral suture. Specimen, Catefica 49-S115851 (holotype, a–c). Scale bars = 300 Μm (a, b), 100 Μm (c).

Text-fig. 22. Scanning electron microscope (SEM, a–c) and synchrotron radiation X-ray tomographic microscopy (SRXTM, d) images of Ibericarpus cuneiformis gen. et sp. nov.; Catefica locality, Portugal. a) Fruiting axis bearing an elongated receptacle with numerous diamond-shaped scars from detached fruitlets; note the absence of scars from bracts, tepals or stamens at the transition to the fruitlet scars and the stalk (arrow); b) Group of ten fruitlets detached from fruiting axis in (a) showing apical stigmatic region and distinctive bulging isodiametric epidermal cells; c) Detached fruitlet showing apical stigmatic region; d) Volume rendering of three adhering fruits showing apical stigmatic region and distinctive bulging isodiametric epidermal cells. Specimens, Catefica MM75-P0477 (a, b), Catefica 49-S115852 (c), Catefica 50-S174907 (d). Scale bars = 300 Μm (a–d).

Text-fig. 23. Synchrotron radiation X-ray tomographic microscopy (SRXTM) images of Ibericarpus cuneiformis gen. et sp. nov.; Catefica locality, Portugal. a) Longitudinal section (orthoslice yz0827) showing fruitlet with apical stigmatic region and a single seed enclosed within the fruitlet wall that has a thick epidermal cuticle; note the tiny embryo (emb) internal to the micropyle (mi) and oriented toward the base of the fruitlet; b) Transverse section through apical part of two fruitlets (orthoslice xy0810) showing the fruitlet wall (fr) composed of small thin-walled cells covered by an epidermis of isodiametric cells (ep) with a thick outer cuticle (cu); c) Longitudinal section (orthoslice xz0370) through basal part of fruitlet perpendicular to section in (a) showing the micropyle (mi), embryo (emb) composed of tiny cells, and the thick cuticle (cu) covering the bulging cells of the fruitlet epidermis. Specimen, Catefica 50-S174907 (a–c). Scale bars = 300 Μm (a–c).