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Text-fig. 32. Scanning electron microscope (SEM) images of "Stamen with monocolpate, reticulate pollen"; Catefica locality, Portugal. a) Stamen with four pollen sacs and an adhering bract (arrow); b) Pollen grains from stamen showing the large gaping, almost circular, aperture with a distinct aperture margin; c) Detail of pollen wall showing finely verrucate supratectal ornamentation and bases of broken columellae; d) Pollen grain showing the large gaping, rounded aperture; e) Pollen grains showing large, rounded aperture (left) and abraded reticulum exposing the surface of the foot layer and long columellae (right). Specimen, Catefica 49-S170144 (a–e). Scale bars = 600 Μm (a), 20 Μm (b), 6 Μm (d, e), 1.5 Μm (c). in The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms

Text-fig. 32. Scanning electron microscope (SEM) images of "Stamen with monocolpate, reticulate pollen"; Catefica locality, Portugal. a) Stamen with four pollen sacs and an adhering bract (arrow); b) Pollen grains from stamen showing the large gaping, almost circular, aperture with a distinct aperture margin; c) Detail of pollen wall showing finely verrucate supratectal ornamentation and bases of broken columellae; d) Pollen grain showing the large gaping, rounded aperture; e) Pollen grains showing large, rounded aperture (left) and abraded reticulum exposing the surface of the foot layer and long columellae (right). Specimen, Catefica 49-S170144 (a–e). Scale bars = 600 Μm (a), 20 Μm (b), 6 Μm (d, e), 1.5 Μm (c).

Text-fig. 27. Scanning electron microscope (SEM) images of stamens and pollen of Valvidistemon globiferus gen. et sp. nov.; Catefica locality, Portugal. a) Stamen in oblique lateral view showing laterally hinged valves, massive connective between the thecae and prominent, globular, apical extension of the connective; b) Stamen in oblique lateral view on the opposite side from (a) showing broken laterally hinged valves and distinct endothecium cells; c) Detail of stamen showing the large, longitudinally aligned cells of the massive connective, broad, poorly defined stamen base, and the laterally hinged valves of one of the thecae; d) Reticulate pollen attached to the inside of the anther wall. Specimen, Catefica 49-S107779 (holotype, a–d). Scale bars = 600 Μm (a, b), 100 Μm (c), 20 Μm (d). in The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms

Text-fig. 27. Scanning electron microscope (SEM) images of stamens and pollen of Valvidistemon globiferus gen. et sp. nov.; Catefica locality, Portugal. a) Stamen in oblique lateral view showing laterally hinged valves, massive connective between the thecae and prominent, globular, apical extension of the connective; b) Stamen in oblique lateral view on the opposite side from (a) showing broken laterally hinged valves and distinct endothecium cells; c) Detail of stamen showing the large, longitudinally aligned cells of the massive connective, broad, poorly defined stamen base, and the laterally hinged valves of one of the thecae; d) Reticulate pollen attached to the inside of the anther wall. Specimen, Catefica 49-S107779 (holotype, a–d). Scale bars = 600 Μm (a, b), 100 Μm (c), 20 Μm (d).

Text-fig. 14. Scanning electron microscope (SEM) images of "Stamen with Asteropollis-type pollen sp. 1"; Catefica locality, Portugal. a) Stamen with pollen in situ; b–d) Pollen in situ in stamen in (a) showing poorly defined tetrachotomocolpate aperture and semitectate-reticulate tectum; e) Detail of pollen wall showing semitectate-reticulate tectum with long, scattered columellae supporting the narrow muri; note two irregular rows of minute verrucae ornamenting surface of muri. Specimen, Catefica 50- S170385 (a–e). Scale bars = 600 Μm (a), 20 Μm (b), 6 Μm (c, d), 1.5 Μm (e). in The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms

Text-fig. 14. Scanning electron microscope (SEM) images of "Stamen with Asteropollis-type pollen sp. 1"; Catefica locality, Portugal. a) Stamen with pollen in situ; b–d) Pollen in situ in stamen in (a) showing poorly defined tetrachotomocolpate aperture and semitectate-reticulate tectum; e) Detail of pollen wall showing semitectate-reticulate tectum with long, scattered columellae supporting the narrow muri; note two irregular rows of minute verrucae ornamenting surface of muri. Specimen, Catefica 50- S170385 (a–e). Scale bars = 600 Μm (a), 20 Μm (b), 6 Μm (c, d), 1.5 Μm (e).

Text-fig. 11. Scanning electron microscope (SEM) images of isolated "Stamen fragment with Clavatipollenites-type pollen sp. 2"; Catefica locality, Portugal. a) Fragment of tetrasporangiate stamen with pollen in situ; b) Detail from stamen fragment showing distal and proximal surfaces of in situ pollen grains; c) Pollen grain in distal view showing short colpus with irregular margin and aperture membrane covered by irregular verrucae; d) Detail of pollen wall showing tiny spherical orbicules; e) Detail of pollen wall showing the semitectate-reticulate tectum and long, scattered columellae supporting the narrow muri with finely verrucate supratectal ornamentation. Specimen, Catefica 50-S170389 (a–e). Scale bars = 600 Μm (a), 20 Μm (b), 6 Μm (c), 3 Μm (d), 1.5 Μm (e). in The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms

Text-fig. 11. Scanning electron microscope (SEM) images of isolated "Stamen fragment with Clavatipollenites-type pollen sp. 2"; Catefica locality, Portugal. a) Fragment of tetrasporangiate stamen with pollen in situ; b) Detail from stamen fragment showing distal and proximal surfaces of in situ pollen grains; c) Pollen grain in distal view showing short colpus with irregular margin and aperture membrane covered by irregular verrucae; d) Detail of pollen wall showing tiny spherical orbicules; e) Detail of pollen wall showing the semitectate-reticulate tectum and long, scattered columellae supporting the narrow muri with finely verrucate supratectal ornamentation. Specimen, Catefica 50-S170389 (a–e). Scale bars = 600 Μm (a), 20 Μm (b), 6 Μm (c), 3 Μm (d), 1.5 Μm (e).

Text-fig. 7. Scanning electron microscope (SEM, a–c, e, f) and synchrotron radiation X-ray tomographic microscopy (SRXTM, d) images of fruits and pollen grains of Hedyflora crystallifera; Catefica locality, Portugal. a, b) Lateral view of fruits showing the remains of apical tepals and remains of the hypanthium, which is thicker on the edges of the fruit in (b) (arrows); c) Detail of hypanthium surface between the thickenings on the edges of the fruit showing polygonal cells with a central papilla; d) Transverse section (orthoslice xy0600) of fruit and seed showing the finely crystalliferous endotesta (arrowhead) and sclerified outer tegmen (asterisk); e) Distal view of pollen grain from surface of fruit showing the poorly defined tetrachotomocolpate aperture (daggers indicating the four arms of the aperture) and semi-tectate, reticulate tectum; f) Detail of pollen wall showing narrow muri with indistinctly beaded surface ornamentation of minute verrucae in poorly defined rows and supported by long columellae. Specimens, Catefica 49-S172313 (a), Catefica 49-S153159 (b), Catefica 49-S172324 (c), Catefica 49-S172325 (d), Catefica 50-S170453 (e, f). Scale bars = 300 Μm (a, b), 100 Μm (d), 50 Μm (c), 6 Μm (e), 1.5 Μm (f). in The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms

Text-fig. 7. Scanning electron microscope (SEM, a–c, e, f) and synchrotron radiation X-ray tomographic microscopy (SRXTM, d) images of fruits and pollen grains of Hedyflora crystallifera; Catefica locality, Portugal. a, b) Lateral view of fruits showing the remains of apical tepals and remains of the hypanthium, which is thicker on the edges of the fruit in (b) (arrows); c) Detail of hypanthium surface between the thickenings on the edges of the fruit showing polygonal cells with a central papilla; d) Transverse section (orthoslice xy0600) of fruit and seed showing the finely crystalliferous endotesta (arrowhead) and sclerified outer tegmen (asterisk); e) Distal view of pollen grain from surface of fruit showing the poorly defined tetrachotomocolpate aperture (daggers indicating the four arms of the aperture) and semi-tectate, reticulate tectum; f) Detail of pollen wall showing narrow muri with indistinctly beaded surface ornamentation of minute verrucae in poorly defined rows and supported by long columellae. Specimens, Catefica 49-S172313 (a), Catefica 49-S153159 (b), Catefica 49-S172324 (c), Catefica 49-S172325 (d), Catefica 50-S170453 (e, f). Scale bars = 300 Μm (a, b), 100 Μm (d), 50 Μm (c), 6 Μm (e), 1.5 Μm (f).

Text-fig. 13. Scanning electron microscope (SEM) images of "Staminate inflorescence fragment with Clavatipollenites-type pollen sp. 4"; Catefica locality, Portugal. a) Fragment of stamen whorl from staminate inflorescence showing several closely packed, almost sessile stamens that lack a well-developed filament; b, c) Distal and proximal views of pollen grains showing poorly defined aperture with verrucate aperture membrane; d) Detail of pollen wall showing the semitectate-reticulate tectum and long, scattered columellae supporting the narrow muri with finely verrucate supratectal ornamentation. Specimen, Catefica 49-S107782 (a–d). Scale bars = 600 Μm (a), 6 Μm (b, c), 1.5 Μm (d). in The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms

Text-fig. 13. Scanning electron microscope (SEM) images of "Staminate inflorescence fragment with Clavatipollenites-type pollen sp. 4"; Catefica locality, Portugal. a) Fragment of stamen whorl from staminate inflorescence showing several closely packed, almost sessile stamens that lack a well-developed filament; b, c) Distal and proximal views of pollen grains showing poorly defined aperture with verrucate aperture membrane; d) Detail of pollen wall showing the semitectate-reticulate tectum and long, scattered columellae supporting the narrow muri with finely verrucate supratectal ornamentation. Specimen, Catefica 49-S107782 (a–d). Scale bars = 600 Μm (a), 6 Μm (b, c), 1.5 Μm (d).

Text-fig. 6. Scanning electron microscope (SEM, a, g, h) and synchrotron radiation X-ray tomographic microscopy (SRXTM, b–f) images of fruits and pollen grains of Canrightiopsis crassitesta (a–c, g, h) and fruit of Canrightiopsis intermedia (d–f); Catefica locality, Portugal. a) Dorsal view of fruit showing rim of hypanthium (arrowheads); b) Surface rendering of longitudinal section in the median plane of fruit (cut between orthoslices yz0440-0510) showing the thin fruit wall, thick endotesta of the seed coat (en, dark blue) and the orthotropous, pendent seed with the chalaza (ch) near the fruit apex and the micropyle (mi) at the fruit base; note the tiny embryo (emb) adjacent to the micropyle at the base of the fruit; c) Longitudinal section (orthoslice xz0511) through the seed wall showing the thick, finely crystalliferous endotesta (en) surrounding the nutritive tissue of the seed; d) Surface rendering of fruit in dorsal view showing rim of the hypanthium (arrowheads) and apical stigmatic region (st); e) Surface rendering of longitudinal section of fruit in (d) (cut at orthoslice xz0560) showing the crystalliferous endotesta (en, dark blue) and the inner tissues of the seed; f) Longitudinal section (orthoslice xz0560) through fruit and seed showing the finely crystalliferous endotesta (en) and thin fruit wall (fr); g, h) Pollen grains from apical region of fruit showing poorly defined margin of the single colpus, reticulate tectum and muri ornamented by minute verrucae. Specimens, Catefica 343-S174311 (a), Catefica 49-S174159 (b, c), Catefica 50-S174905 (d–f), Catefica 342-S122089 (g, h). Scale bars = 300 Μm (a, b, d, e), 150 Μm (c, f), 6 Μm (g), 3 Μm (h). g, h published with permission from Grana. in The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms

Text-fig. 6. Scanning electron microscope (SEM, a, g, h) and synchrotron radiation X-ray tomographic microscopy (SRXTM, b–f) images of fruits and pollen grains of Canrightiopsis crassitesta (a–c, g, h) and fruit of Canrightiopsis intermedia (d–f); Catefica locality, Portugal. a) Dorsal view of fruit showing rim of hypanthium (arrowheads); b) Surface rendering of longitudinal section in the median plane of fruit (cut between orthoslices yz0440-0510) showing the thin fruit wall, thick endotesta of the seed coat (en, dark blue) and the orthotropous, pendent seed with the chalaza (ch) near the fruit apex and the micropyle (mi) at the fruit base; note the tiny embryo (emb) adjacent to the micropyle at the base of the fruit; c) Longitudinal section (orthoslice xz0511) through the seed wall showing the thick, finely crystalliferous endotesta (en) surrounding the nutritive tissue of the seed; d) Surface rendering of fruit in dorsal view showing rim of the hypanthium (arrowheads) and apical stigmatic region (st); e) Surface rendering of longitudinal section of fruit in (d) (cut at orthoslice xz0560) showing the crystalliferous endotesta (en, dark blue) and the inner tissues of the seed; f) Longitudinal section (orthoslice xz0560) through fruit and seed showing the finely crystalliferous endotesta (en) and thin fruit wall (fr); g, h) Pollen grains from apical region of fruit showing poorly defined margin of the single colpus, reticulate tectum and muri ornamented by minute verrucae. Specimens, Catefica 343-S174311 (a), Catefica 49-S174159 (b, c), Catefica 50-S174905 (d–f), Catefica 342-S122089 (g, h). Scale bars = 300 Μm (a, b, d, e), 150 Μm (c, f), 6 Μm (g), 3 Μm (h). g, h published with permission from Grana.

Text-fig. 12. Scanning electron microscope (SEM) images of isolated "Stamen fragment with Clavatipollenites-type pollen sp. 3"; Catefica locality, Portugal. a) Stamen fragment with pollen in situ; b, c) Pollen grains showing the semitectate-reticulate pollen wall and folds (c) indicating a possible monocolpate aperture; d) Detail of pollen wall showing the semitectate-reticulate tectum and long, scattered columellae supporting the narrow muri with finely verrucate supratectal ornamentation; e) Detail of pollen wall showing tiny, spherical, finely spiny orbicules. Specimen, Catefica 50-S170449 (a–e). Scale bars = 600 Μm (a), 6 Μm (b, c), 1.5 Μm (d, e). in The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms

Text-fig. 12. Scanning electron microscope (SEM) images of isolated "Stamen fragment with Clavatipollenites-type pollen sp. 3"; Catefica locality, Portugal. a) Stamen fragment with pollen in situ; b, c) Pollen grains showing the semitectate-reticulate pollen wall and folds (c) indicating a possible monocolpate aperture; d) Detail of pollen wall showing the semitectate-reticulate tectum and long, scattered columellae supporting the narrow muri with finely verrucate supratectal ornamentation; e) Detail of pollen wall showing tiny, spherical, finely spiny orbicules. Specimen, Catefica 50-S170449 (a–e). Scale bars = 600 Μm (a), 6 Μm (b, c), 1.5 Μm (d, e).

Text-fig. 26. Scanning electron microscope (SEM) images of stamens and pollen grains of Elasmostemon paisii gen. et sp. nov. (a–c) and laminar stamens with monocolpate reticulate pollen sp. (d–g); Catefica locality, Portugal. a) Stamen fragment with basal portion missing showing two pairs of pollen sacs on one surface of the stamen close to the margin and separated by a broad connective, except near the apex where the thecae meet; note that the thecae are dehisced with the walls of the pollen sacs curled back; b) Pollen grains inside a dehisced pollen sac; note variation in size and development of the reticulum; c) Detail of (b) showing monocolpate, reticulate pollen with lumen of reticulum varying markedly in size but partly obscured by residual organic material; d) Stamen with apical and basal part of anther preserved showing two pairs of pollen sacs (asterisks) on the curved, perhaps ventral, surface close to the stamen margin; e) Detail of crack in the anther showing the inner anther wall with densely spaced spherical orbicules that vary greatly in size; f) Pollen exposed in the crack in the anther; note coarsely foveolate to coarsely reticulate pollen wall and densely spaced orbicules; g) Folded pollen grains with reticulate pollen wall and also showing the inner anther wall with densely spaced spherical orbicules that vary greatly in size. Specimens, Catefica 49-S172560 (a–c), Catefica 50- S170384 (d–g). Scale bars = 600 Μm (a, d), 20 Μm (b, e), 6 Μm (c, f, g). in The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms

Text-fig. 26. Scanning electron microscope (SEM) images of stamens and pollen grains of Elasmostemon paisii gen. et sp. nov. (a–c) and laminar stamens with monocolpate reticulate pollen sp. (d–g); Catefica locality, Portugal. a) Stamen fragment with basal portion missing showing two pairs of pollen sacs on one surface of the stamen close to the margin and separated by a broad connective, except near the apex where the thecae meet; note that the thecae are dehisced with the walls of the pollen sacs curled back; b) Pollen grains inside a dehisced pollen sac; note variation in size and development of the reticulum; c) Detail of (b) showing monocolpate, reticulate pollen with lumen of reticulum varying markedly in size but partly obscured by residual organic material; d) Stamen with apical and basal part of anther preserved showing two pairs of pollen sacs (asterisks) on the curved, perhaps ventral, surface close to the stamen margin; e) Detail of crack in the anther showing the inner anther wall with densely spaced spherical orbicules that vary greatly in size; f) Pollen exposed in the crack in the anther; note coarsely foveolate to coarsely reticulate pollen wall and densely spaced orbicules; g) Folded pollen grains with reticulate pollen wall and also showing the inner anther wall with densely spaced spherical orbicules that vary greatly in size. Specimens, Catefica 49-S172560 (a–c), Catefica 50- S170384 (d–g). Scale bars = 600 Μm (a, d), 20 Μm (b, e), 6 Μm (c, f, g).

Text-fig. 30. Scanning electron microscope (SEM) images of anther and pollen of Kempia longicolpites; Catefica locality, Portugal. a) Transverse section through an anther showing the four pollen sacs with in situ pollen; b) Pollen in situ from anther in (a) showing very long colpus and loosely attached reticulum; c) Detail of reticulum showing smooth muri supported by short, scattered columellae; d) Pollen grain from anther in (a) enlarged showing colpus extended beyond the equator and loosely attached reticulum; e) Detail of pollen wall showing thick, homogeneous foot layer, columellae and reticulate tectum; note remains of granular endexine (arrows) in the apertural region of the grain; f) Internal view of reticulum showing the short columellae adhering to the muri detached from the foot layer. Specimen, Catefica 49-S101208 (a–f). Scale bars = 100 Μm (a), 20 Μm (b), 6 Μm (d), 3 Μm (c, e, f). in The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms

Text-fig. 30. Scanning electron microscope (SEM) images of anther and pollen of Kempia longicolpites; Catefica locality, Portugal. a) Transverse section through an anther showing the four pollen sacs with in situ pollen; b) Pollen in situ from anther in (a) showing very long colpus and loosely attached reticulum; c) Detail of reticulum showing smooth muri supported by short, scattered columellae; d) Pollen grain from anther in (a) enlarged showing colpus extended beyond the equator and loosely attached reticulum; e) Detail of pollen wall showing thick, homogeneous foot layer, columellae and reticulate tectum; note remains of granular endexine (arrows) in the apertural region of the grain; f) Internal view of reticulum showing the short columellae adhering to the muri detached from the foot layer. Specimen, Catefica 49-S101208 (a–f). Scale bars = 100 Μm (a), 20 Μm (b), 6 Μm (d), 3 Μm (c, e, f).

Text-fig. 10. Scanning electron microscope (SEM) images of isolated "Stamen fragment with Clavatipollenites-type pollen sp. 1"; Catefica locality, Portugal. a) Fragment of tetrasporangiate stamen with pollen in situ; b) Detail from stamen fragment showing distal and proximal surfaces of in situ pollen grains and tiny orbicules on the inner surface of the anther wall (arrows); c) Pollen grains in distal view showing short colpi with irregular margins and aperture membrane with irregular verrucae; d) Detail of pollen wall showing the semitectate-reticulate tectum and long, scattered columellae supporting the narrow muri with finely verrucate supratectal ornamentation. Specimen, Catefica 50-S170387 (a–d). Scale bars = 600 Μm (a), 20 Μm (b), 6 Μm (c), 1.5 Μm (d). in The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms

Text-fig. 10. Scanning electron microscope (SEM) images of isolated "Stamen fragment with Clavatipollenites-type pollen sp. 1"; Catefica locality, Portugal. a) Fragment of tetrasporangiate stamen with pollen in situ; b) Detail from stamen fragment showing distal and proximal surfaces of in situ pollen grains and tiny orbicules on the inner surface of the anther wall (arrows); c) Pollen grains in distal view showing short colpi with irregular margins and aperture membrane with irregular verrucae; d) Detail of pollen wall showing the semitectate-reticulate tectum and long, scattered columellae supporting the narrow muri with finely verrucate supratectal ornamentation. Specimen, Catefica 50-S170387 (a–d). Scale bars = 600 Μm (a), 20 Μm (b), 6 Μm (c), 1.5 Μm (d).

Text-fig. 29. Scanning electron microscope (SEM) images of stamens and pollen grains of cf. Endressistemon sp. 1 (a, b), cf. Endressistemon sp. 2 (c, d) and cf. Endressistemon sp. 3 (e–g); Catefica locality, Portugal. a) Two adhering stamens, each with a long, pointed extension of the connective; b) Monocolpate, reticulate pollen in situ in stamen from stamen pair in (a); c) Fragment of stamen with prominent apical extension of the connective; d) Reticulate, apparently monocolpate, pollen in situ in stamen fragment in (c); e) Stamen with basifixed anther, perhaps sessile, and with prominent, wing-like apical extensions of the connective; note the dehisced thecae with the anther wall curved back; f, g) Monocolpate, reticulate pollen in situ in stamen in (e). Specimens, Catefica 49-S107780 (a, b), Catefica 49-S107784 (c, d), Catefica 49-S107781 (e–g). Scale bars = 600 Μm (a, c, e), 6 Μm (b, d, f, g). in The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms

Text-fig. 29. Scanning electron microscope (SEM) images of stamens and pollen grains of cf. Endressistemon sp. 1 (a, b), cf. Endressistemon sp. 2 (c, d) and cf. Endressistemon sp. 3 (e–g); Catefica locality, Portugal. a) Two adhering stamens, each with a long, pointed extension of the connective; b) Monocolpate, reticulate pollen in situ in stamen from stamen pair in (a); c) Fragment of stamen with prominent apical extension of the connective; d) Reticulate, apparently monocolpate, pollen in situ in stamen fragment in (c); e) Stamen with basifixed anther, perhaps sessile, and with prominent, wing-like apical extensions of the connective; note the dehisced thecae with the anther wall curved back; f, g) Monocolpate, reticulate pollen in situ in stamen in (e). Specimens, Catefica 49-S107780 (a, b), Catefica 49-S107784 (c, d), Catefica 49-S107781 (e–g). Scale bars = 600 Μm (a, c, e), 6 Μm (b, d, f, g).

Text-fig. 28. Scanning electron microscope (SEM) images of stamens and pollen of Endressistemon cateficensis gen. et sp. nov.; Catefica locality, Portugal. a, b) Staminal structure with two lateral stamens and one median structure seen in ventral and dorsal view (orientation unknown) showing that each stamen has a prominent apical extension and two pairs of pollen sacs separated by a narrow connective; both stamens are borne on a common base together with the median structure and their anthers are sessile on the common stalk; note the apical projection of the median structure (asterisk) between the two stamens and the ribs over probable vascular bundles that extend from the common base into the apical projections of both stamens and the median structure (arrows); c) Staminal structure showing two stamens with prominent apical projections and median axis-like structure between the two stamens (arrow); d) Staminal structure showing two stamens with prominent apical projections borne on a common base; e) Staminal structure in (a) and (b), from the same orientation as (b), showing the ribs over probable vascular bundles (yellow) that extend into the apical projections; f) Detail of staminal structure in (a) and (b) showing the fused or strongly adhering apical projections of the two lateral stamens and the median structure (asterisk); g) Monocolpate, reticulate pollen grains from the pollen sacs of stamen in (d). Specimens, Catefica 49-S107778 (holotype, a, b, e, f), Catefica 49-S107769 (c), Catefica 49-S107751 (d, g). Scale bars = 600 Μm (a–d), 300 Μm (e), 100 Μm (f), 6 Μm (g). in The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms

Text-fig. 28. Scanning electron microscope (SEM) images of stamens and pollen of Endressistemon cateficensis gen. et sp. nov.; Catefica locality, Portugal. a, b) Staminal structure with two lateral stamens and one median structure seen in ventral and dorsal view (orientation unknown) showing that each stamen has a prominent apical extension and two pairs of pollen sacs separated by a narrow connective; both stamens are borne on a common base together with the median structure and their anthers are sessile on the common stalk; note the apical projection of the median structure (asterisk) between the two stamens and the ribs over probable vascular bundles that extend from the common base into the apical projections of both stamens and the median structure (arrows); c) Staminal structure showing two stamens with prominent apical projections and median axis-like structure between the two stamens (arrow); d) Staminal structure showing two stamens with prominent apical projections borne on a common base; e) Staminal structure in (a) and (b), from the same orientation as (b), showing the ribs over probable vascular bundles (yellow) that extend into the apical projections; f) Detail of staminal structure in (a) and (b) showing the fused or strongly adhering apical projections of the two lateral stamens and the median structure (asterisk); g) Monocolpate, reticulate pollen grains from the pollen sacs of stamen in (d). Specimens, Catefica 49-S107778 (holotype, a, b, e, f), Catefica 49-S107769 (c), Catefica 49-S107751 (d, g). Scale bars = 600 Μm (a–d), 300 Μm (e), 100 Μm (f), 6 Μm (g).

Text-fig. 8. Scanning electron microscope (SEM) images of staminate inflorescences and pollen of Proencistemon portugallicus gen. et sp. nov.; Catefica locality, Portugal. a, b) Staminate inflorescences composed of numerous tetrasporangiate stamens; each stamen lacks a filament and there is no clear indication of other floral organs; note apparently paired arrangement of stamens in (b) (asterisks); c) Pollen in situ in anther from specimen in (a) showing poorly defined trichotomocolpate aperture and semitectate-reticulate tectum; d) Detail of pollen from specimen in (a) showing narrow muri with beaded surface ornamentation; e) Distal and proximal views of pollen in situ in an anther fragment; f) Orbicules attached to surface of in situ pollen from anther fragment. Specimens, Catefica M282-P0341 (holotype, a, c, d), Catefica 150-S174257 (b), Catefica 50-S170393 (e, f). Scale bars = 600 Μm (a, b), 6 Μm (c, e), 1.5 Μm (d, f). in The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms

Text-fig. 8. Scanning electron microscope (SEM) images of staminate inflorescences and pollen of Proencistemon portugallicus gen. et sp. nov.; Catefica locality, Portugal. a, b) Staminate inflorescences composed of numerous tetrasporangiate stamens; each stamen lacks a filament and there is no clear indication of other floral organs; note apparently paired arrangement of stamens in (b) (asterisks); c) Pollen in situ in anther from specimen in (a) showing poorly defined trichotomocolpate aperture and semitectate-reticulate tectum; d) Detail of pollen from specimen in (a) showing narrow muri with beaded surface ornamentation; e) Distal and proximal views of pollen in situ in an anther fragment; f) Orbicules attached to surface of in situ pollen from anther fragment. Specimens, Catefica M282-P0341 (holotype, a, c, d), Catefica 150-S174257 (b), Catefica 50-S170393 (e, f). Scale bars = 600 Μm (a, b), 6 Μm (c, e), 1.5 Μm (d, f).

Text-fig. 9. Scanning electron microscope (SEM) images of stamens and pollen of Proencistemon portugallicus gen. et sp. nov. (a–g) and Proencistemon sp. (h–j); Catefica locality, Portugal. a) Fragment of stamen whorl from staminate inflorescence showing almost sessile anthers; note short bracts at the base of the stamen whorl (arrow) and apparent paired arrangement of the stamens; b) Fragment of stamen whorl showing almost sessile anthers and apparent paired arrangement of the stamens; c) Pollen in situ from stamen whorl in (b) showing poorly defined trichotomocolpate aperture and semitectate-reticulate tectum; d–g) Distal views of pollen in situ from pollen clump showing poorly defined trichotomocolpate aperture, semitectate-reticulate tectum (d–f), and fractured pollen wall with long, scattered columellae supporting narrow muri (g); h) Fragment of staminate inflorescence with narrow, almost sessile, stamens; i, j) Pollen from fragment of staminate inflorescence in (h) showing poorly defined trichotomocolpate aperture (i), semitectate-reticulate tectum (i, j) and long, scattered columellae supporting narrow muri (j). Specimens, Catefica 49-S266015 (a), Catefica 342-S122086 (b, c), Catefica 50-S170394 (d–g), Catefica 49-S107783 (h–j). Scale bars = 600 Μm (a, b, h), 6 Μm (c–f, i), 1.5 Μm (g, j). in The Early Cretaceous Mesofossil Flora Of Catefica, Portugal: Angiosperms

Text-fig. 9. Scanning electron microscope (SEM) images of stamens and pollen of Proencistemon portugallicus gen. et sp. nov. (a–g) and Proencistemon sp. (h–j); Catefica locality, Portugal. a) Fragment of stamen whorl from staminate inflorescence showing almost sessile anthers; note short bracts at the base of the stamen whorl (arrow) and apparent paired arrangement of the stamens; b) Fragment of stamen whorl showing almost sessile anthers and apparent paired arrangement of the stamens; c) Pollen in situ from stamen whorl in (b) showing poorly defined trichotomocolpate aperture and semitectate-reticulate tectum; d–g) Distal views of pollen in situ from pollen clump showing poorly defined trichotomocolpate aperture, semitectate-reticulate tectum (d–f), and fractured pollen wall with long, scattered columellae supporting narrow muri (g); h) Fragment of staminate inflorescence with narrow, almost sessile, stamens; i, j) Pollen from fragment of staminate inflorescence in (h) showing poorly defined trichotomocolpate aperture (i), semitectate-reticulate tectum (i, j) and long, scattered columellae supporting narrow muri (j). Specimens, Catefica 49-S266015 (a), Catefica 342-S122086 (b, c), Catefica 50-S170394 (d–g), Catefica 49-S107783 (h–j). Scale bars = 600 Μm (a, b, h), 6 Μm (c–f, i), 1.5 Μm (g, j).

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Widespread reticulate evolution in an adaptive radiation

<p>A fundamental assumption of evolutionary biology is that phylogeny follows a bifurcating process. However, hybrid speciation and introgression are becoming more widely documented in many groups. Hybrid inference studies have been historically limited to small sets of taxa, while exploration of the prevalence and trends of reticulation at deep time scales remains unexplored. We study the evolutionary history of an adaptive radiation of 109 gemsnakes in Madagascar (Pseudoxyrhophiinae) to identify potential instances of introgression. Using several network inference methods, we find twelve reticulation events within the 22-million-year evolutionary history of gemsnakes, producing 28% of the diversity for the group, including one reticulation that resulted in the diversification of an 18 species radiation. These reticulations occur at nodes with high gene tree discordance. Hybridization events occurred between north-south distributed parentals that share similar ecologies. Younger hybrids occupy intermediate contact zones between the parentals, showing that post-speciation dispersal in this group has not eroded the spatial signatures of introgression. Reticulations accumulated consistently over time, despite drops in overall speciation rates during the Pleistocene. This suggests that while bifurcating speciation may decline as the result of species accumulation and environmental change, speciation by hybridization may be more robust to these processes.</p>

Figure 3 in A phylogenetic analysis of the grape genus (Vitis L.) reveals broad reticulation and concurrent diversification during neogene and quaternary climate change

Figure 3 Chronogram of Bayesian divergence time estimates of Vitis diversification based on 27 concatenated nuclear gene fragments inferred using the BEAST software. Grey bars represent the 95% Highest Posterior Density (HPD) intervals of nodal age in million years. Calibration points are indicated with filled circles. Significant evolutionary events are indicated with black diamonds. Asterisk indicates inclusion of a clonally propagated cultivar that may affect the local divergence estimate. Additional files 4 and 5 show nodal ages and posterior probabilities for all nodes in this tree.

Figure 1 in A phylogenetic analysis of the grape genus (Vitis L.) reveals broad reticulation and concurrent diversification during neogene and quaternary climate change

Figure 1 Native geographic distribution of the genus Vitis (grey shading1) and geographic regions of origin of Vitis species used in this study. Dashed lines indicate southern borders of the polar ice cap during the most recent ice age2. Dash-dot lines indicate ice age refugia of the forest flora2. Areas labeled 1 through 4 were used in ancestral area optimization (reversible parsimony, Additional file 14). Redrawn from 1Alleweldt et al. [7], 2Reinig [14].

Figure 6 in A phylogenetic analysis of the grape genus (Vitis L.) reveals broad reticulation and concurrent diversification during neogene and quaternary climate change

Figure 6 Simplified version (cartoon) of the MP strict consensus tree. Blue = North and Central American accessions, Green = Asian accessions, Red = European accessions. For comparison, Additional files 6 and 10 represent cartoons of the ML and BA trees, respectively.

Figure 5 in A phylogenetic analysis of the grape genus (Vitis L.) reveals broad reticulation and concurrent diversification during neogene and quaternary climate change

Figure 5 Hypothesis of phylogenetic relationships among Vitis species. Eurasia. Continuation of Figure 4.