Lithophyllum pustulatum (J.V.Lamouroux) Foslie, 1904: 8

Tâmega, Frederico T. S., Spotorno-Oliveira, Paula, Coutinho, Ricardo & Bassi, Davide, 2016, Taxonomic assessment of fossil Holocene coralline red algae (Rhodophyta, Corallinales, Hapalidiales) from southwestern Atlantic, Phytotaxa 245 (4), pp. 237-250 : 239-241

Lithophyllum pustulatum (J.V.Lamouroux) Foslie, 1904: 8 ( Figs. 2–5 )

Basionym: — Melobesia pustulata J.V. Lamouroux, 1816: 315 , pl XII, fig. 2

Lectotype: — CN (Herb. Lamouroux) unnumbered ( Womersley, 1996: 229)

Type locality: — France ( Silva, Basson & Moe, 1996:274)

Synonyms: — Woelkerling & Campbell (1992).

Age: — Praia do Farol —12,910 –12,690 Cal yrs B. P. (2σ) ; Prainhas do Pontal —3,370 –3,185 Cal yrs B. P. (2σ) .

Material examined: — BRAZIL. Rio de Janeiro State, Arraial do Cabo, Praia do Farol, Cabo Frio Island (23°00.090`S, 042°00.248`W, 1.5 m above sea level, 15 May 2014, F. T. de S. Tâmega, IEAPM 00332) and Prainhas do Pontal (22°59’18.8” S, 42°00’47.1” W, 2.14 m above sea level, 14 August 2014, F. T. de S. Tâmega & P. S-Oliveira, IEAPM 00333).

Description: —Thalli non-geniculate, encrusting ( Fig. 2 ); internal construction dimerous; dorsiventral organization with a unistratose primigenous filaments composed of palisade rectangular cells ( Fig. 3 ); dorsal cell filaments with palisade rectangular cells ( Fig. 3 ) and measure 6–10 μm in length and 5–7 μm in diameter. Cells of adjacent primigenous and dorsal filaments joined by secondary pit connections; cell fusions not observed. Well-defined cell walls separate adjacent filaments, and the absence of cell fusions indicate that only secondary pit connections are present.

Gametangial thalli were not observed. Mature empty conceptacles uniporate, ellipsoidal in section, with a flat floor and an arcuate roof and flush with, one to three cell layers bellow the surrounding vegetative thallus surface ( Fig. 4 ); conceptacle chambers 186–513 μm in diameter and 115–211 μm in height ( Fig. 5 ).

Remarks: —Molecular evidence (e.g., Broom et al. 2008) suggests that Lithophyllum Philippi, 1837: 387 and Titanoderma Nägeli, 1858 represent distinct genera, but generic boundaries remain blurred on morphological/anatomical grounds (see Braga 2003, Harvey et al. 2009, Villas-Bôas et al. 2009, Bittner et al. 2011, Iryu et al. 2012), and as a result, these genera have been treated as a complex using the oldest generic name, Lithophyllum ( Woelkerling et al. 2002, p. 370, Braga & Aguirre 2004). Since we studied samples in thin section, specimens ascribed to L. pustulatum in this study encompass thalli with dimerous organization, primigenous filaments usually composed of palisade cells, and postigenous filaments composed of only epithallial cells (rarely preserved in fossil plants) or epithallial and a few subtending cells. Conceptacle characteristics found in the studied material show similarities with those previously reported for present-day material in the British Isles ( Chamberlain 1991), Australia ( Woelkerling & Campbell 1992), Caribbean ( Littler & Littler 2000), New Zealand ( Harvey et al. 2005) and Brazil ( Henriques et al. 2014), with only minor differences in the conceptacle height and diameter ( Table 2).

2) Encrusting thallus with several tangential peripheral sections of conceptacles (c).

3) Magnification of Fig. 2 : dimerous dorsiventral organization with ventral palisade cells (p).

4) Detail of Fig. 2 : conceptacles (c) which arise from the surface of individual dimerous thalli and become overgrown by other dimerous thalli.

5) Oblique longitudinal section of a uniporate conceptale (arrow) with floor two to three cell layers below surrounding vegetative thallus surface.

Geographical and stratigraphic distribution: —See Guiry &Guiry (2015) for a detailed geographical distribution list. This species has been recorded from the Late Oligocene to the Recent ( Bassi et al. 2009).

Subfamily Corallinoideae (J.E. Areschough) Foslie, 1908: 19

Unidentified geniculate coralline algae

Age: —Prainhas do Pontal —3,370 –3,185 Cal yrs B.P. (2σ).

Material examined: — BRAZIL. Rio de Janeiro State,Arraial do Cabo, Prainhas do Pontal (22°59’18.8” S, 42°00’47.1” W, 2.14 m above sea level, 14 August 2014, F. T. de S. Tâmega & P. S-Oliveira, IEAPM 00333).

Description: —Geniculate corallines occur in packstone and grainstone deposits and are represented by calcified intergenicula formed by a medulla of regular parallel rows ( Fig. 6 ). Calcified cylindrical intergenicula, are composed of arching tiers of medullary cells. These cells are all the same height, without pit-connections. No geniculum and reproductive structure were identified, thus precluding their certain placement within a Corallinoideae genus.

Different combinations of vegetative morphological and anatomical reproductive characters circumscribe the genera and species within this subfamily (e.g., Riosmena-Rodríguez & Siqueiros-Beltrones 1996, Mendoza González et al. 2014). The absence of adequate information on conceptacles and genicula for the studied specimens precludes their certain placement in a Corallinoideae genus.

Subfamily Mastophoroideae W.A. Setchell, 1943: 134

Figures

FIGURE 6. Two specimens of unidentified geniculate coralline algae showing the calcified intergenicula formed by a medulla of regular parallel rows. Sample IEAPM 00333, Arraial do Cabo; scale bar = 200 μm.

FIGURE 2–5. Lithophyllum pustulatum, sample IEAPM 00333, Arraial do Cabo; scale bar = 200 μm.