Coriaripites goodii Barreda, Palazzesi & M.C.Tellería, sp., 2020

Renner, Susanne S., Barreda, Viviana D., Tellería, María Cristina, Palazzesi, Luis & Schuster, Tanja M., 2020, Early evolution of Coriariaceae (Cucurbitales) in light of a new early Campanian (ca. 82 Mya) pollen record from Antarctica, TAXON 69 (1), pp. 87-99 : 96-97

Coriaripites goodii Barreda, Palazzesi & M.C.Tellería, sp.

nov. – Holotype: Specimen on slide 611b: C54-1 (sample

6 from Barreda & al., 2019) earliest Maastrichtian; occurs

in trace numbers in early Campanian–early Maastrichtian

sequences of the Santa Marta, Snow Hill Island and

Lopez de Bertodano Formations, Snow Hill and Vega

Islands , Antarctica. Paratype: Specimen on slide 698b :

E30-2 (sample 23 from Barreda & al., 2019): early

Campanian; same locality as the holotype.

For images of the holotype and paratype, see Fig. 5A,B and 5G,H , respectively.

Diagnosis. – Pollen grain free, isopolar, tricolporate, or tetracolporate, fastigiate, suboblate, amb circular to subcircular with convex sides. Colpi short and narrow (ca. 4–6 μm), slit-like, fastigium 4–8 μm wide, 2–3 μm deep in polar view, ora circular to subcircular, ca. 2–3 μm in diameter, with slightly thickened margins. Exine 1–1.5 μm thick, tectate, sexine as thick as nexine, sexine columellate, tectum scabrate, granulate (rugulate) (LM), bearing small spinules (SEM).

Dimensions. – Equatorial diameter: 21–34 μm (6 specimens observed).

Age. – Early Campanian–early Maastrichtian (ca. 82–70 Mya.; Barreda & al., 2019).

Etymology. – In recognition of R.D.O. Good, who first postulated a southern connection route for the Coriariaceae where these pollen grains come from.

Remarks and comparisons. — Coriaripites alienus Sat. K.Srivast. from the Maastrichtian of Canada ( Srivastava, 1969) differs from the pollen grains described here in having aspidate instead of fastigiate apertures and obscure exine stratification. The illustration of pollen referred to as Coriaripites sp. cf. C. alienus ( Jarzen & Norris, 1975: pl. 2, fig. 21), also from the Maastrichtian of Canada, shows broad similarities, but no description was provided. Muller (1981) considered these specimens to differ from modern Coriaria pollen by having a very thin exine wall and more pronounced colpi. Other brevitricolporate specimens with broad similarities to Coriaripites goodii were reported from the middle Turonian- Santonian of the Gulf and Atlantic Coastal Plain of North America, which are Porocolpopollenites ( Leopold & Pakiser, 1964; Doyle, 1969), and aff. Porocolpopollenites ( Doyle & Robbins, 1977) , both later placed in Sohlipollis ( Christopher & al., 1999). These fossils have similarities in pollen grain shape, size, and general sculpture, however they have subequatorial “nexinal costae” that border each colpus. More importantly, Sohlipollis lacks the fastigium typical of Coraria, because the nexine remains attached to the columellate layer at the apertural level ( Christopher & al., 1999).

Botanical affinity. — Coriaripites goodii sp. nov. shows strong morphological similarities with pollen of extant Coriaria . They share similarities in shape, size, sculpture, exine thickness, and particularly in having tri- and/or tetracolporate fastigiate apertures, with very short colpi ( Figs. 5 , 6 , suppl. Figs. S6 , S7). Among Cucurbitales , the fastigium distinguishes C. goodii from most other members of the order ( Schaefer & Renner, 2011), where only Begoniaceae also have a fastigium, but differ in pollen shape (prolate) and sculpture (striate) ( Van den Berg, 1984, 1985). Pollen grains of Cucurbitaceae differ in size (ca. 50–200 μm) and sculpture (striate, reticulate, or echinate); Apodanthaceae in type of aperture (inaperturate, tricolpate) ( Blarer & al., 2004), and Anisophyllaceae in size (ca. <20 μm), shape (subprolate), type of aperture (tricolporoidate, syncolpate), and sculpture (striate) ( Vezey & al., 1988); Datiscaceae in the type of pollen dispersion (obligate tretrads) ( Davidson, 1973); and Tetramelaceae in pollen grain size (ca. 10–12 μm) and shape (spheroidal) ( Davidson, 1973). Furthermore, the sister family Corynocarpaceae differs in the number of apertures (dicolporate) ( Nowicke & Skvarla, 1983). However, although C. goodii has all morphological features present in extant Coriaria pollen, we cannot exclude the possibility that the fossil pollen grains presented here represent a deeper diverging extinct linage within Cucurbitales .

Pollen of extant Coriaria . — ( Figs. 5C,F,I , 6B , suppl. Figs. S6 , S7). Pollen grains are tricolporate, sometimes tetracolporate, suboblate to oblate-spheroidal, with a more or less elliptic or spheroidal outline in equatorial view and circular to semiangular outline in polar view. Polar axis ranges between 17 and 30 μm in length and equatorial axis between 19 and 34 μm in length ( Table 3). The ectoaperture is always narrow with rounded ends and a scabrate membrane but it may be as long as the diameter of the pore ( Fig. 6B , suppl. Fig. S7A,E,F). The endoaperture is circular to slightly lalongate, commonly forming a fastigium ( Fig. 5 ). Exine is tectate, columellate, with the surface scabrate or rugulate-microgranulate. Ratio sexine/nexine: 1.

Conclusion. — Our Cretaceous record of Coriariaceae from Antarctica represents the oldest for the family and also the oldest record of Cucurbitales ( Collinson & al., 1993). This fossil discovery reinforces the idea of Antarctica as a region of origin and/or dispersal during the Cretaceous of several lineages today occurring in the temperate regions of the Southern Hemisphere.

Figures

Fig. 5. Fossil and extant representatives of Coriariaceae observed with light microscopy. A, B, D, E, G & H, Pollen of Coriaripites goodii sp. nov. from the late Cretaceous of Antarctica (blue frames). A & B, Pollen on slide BA-Pal. ex CIRGEO Palin 611b: C54-1; D & E, Pollen on slide BA-Pal. ex CIRGEO Palin 963b: R31-1; G & H, Pollen on slide BA-Pal. ex CIRGEO Palin 698b: E30-2. All grains in polar view. A & B, Note the well-defined fastigium and short colpi with pointed ends (arrowheads); D & E, Note stratified thin exine and short colpi (arrowheads); G & H, Pollen with four apertures; note clearly defined fastigium and very short colpi (arrowheads).C, F & I, Pollen of extant species for comparison (magenta frames). C, Extant Coriaria plumosa; F, Extant Coriaria ruscifolia; I, Extant Coriaria myrtifolia, pollen with four apertures and clearly defined fastigium (arrowhead). — Scale bars = 5 μm.

Fig. 6. Fossil and extant representatives of Coriariaceae observed with scanning electron microscopy. A, Pollen of Coriaripites goodii sp. nov. from the late Cretaceous of Antarctica (blue frame); polar view showing details of sculpture, big apocolpium and short colpi (arrowheads); B, Extant pollen of Coriaria arborea (magenta frame); polar view showing details of sculpture and colpi length (arrowhead). — Scale bars = 5 μm.