Hydrolithon lemoinei ( Miranda, 1935 ) Aguirre, Braga, and Bassi, 2011

Hrabovský, Juraj, 2019, Reproductive phases of Miocene algae from central Paratethys and their bearing on systematics, Acta Palaeontologica Polonica 64 (2), pp. 417-439 : 425-429

Hydrolithon lemoinei ( Miranda, 1935) Aguirre, Braga, and Bassi, 2011

1973 Lithophyllum (Dermatolithon) sp.; Schaleková 1973: 218, pl. 74: 2.

Material.—Bi/tetrasporangial plant ( Fig. 4A), NHM B1842 (thin section 5227), early Langhian, Rohožník, Slovakia (Vienna Basin). Spermatangial plant ( Fig. 4B), NHM B1843 (thin section 5228) from the same locality as bi/tetrasporophyte. Carpogonial-carposporangial conceptacles ( Fig. 4C), NHM B1844 (thin section 6174), early Langhian, Kamenica nad Hronom, Slovakia (Danube Basin). Other examined bi/tetrasporophytes ( Table 5): NHM B1845 (thin section VZ20), early Langhian, Kosihovce, Slovakia (Novohrad Basin); NHM B1846 (thin section IIIb/458), early Langhian, Pavlová, Slovakia (Danube Basin); NHM B1847 (thin section DK C), early Serravallian, Devínska Kobyla, Slovakia (Vienna Basin); NHM B1838/2(thin section184911651),early Langhian, Lopadea Veche, Romania (Transylvania Basin). Gametophyte, NHM B1838/3 (thin section 184911651), early Langhian, Lopadea Veche, Romania (Transylvania Basin).

Specimens from Schaleková’s collection ( Schaleková 1973)bi/tetrasporophyte thin section VEGA 5105,early Serravallian, Rohožník, Slovakia (Vienna Basin). Hydrolithon lemoinei specimens from new samples: both bi/tetrasporo-

Fig. 4. Coralline alga Hydrolithon lemoinei ( Miranda, 1935) Aguirre, Braga, and Bassi, 2011 . A. Bi/tetrasporophyte, NHM B1842 (thin section 5227), early → Serravallian, Rohožník, Slovakia, Vienna Basin. A 1. Encrusting growth form with distinct projection of bi/tetrasporangial conceptacles. A 2. Dorsiventral internal organisation and dimerous construction (white arrows point to the lateral fusion of cells in adjacent filaments); note small flattened epithallial cells at the surface and elongated meristematic cells (black arrow). Large polygonal cell producing two long and narrow cells is on the right margin. A 3.

Dome shaped epithallial cells (arrow). A 4. Pore canal filaments and proposed papillae that protrude inside (arrow). B. Male gametophyte, NHM B1843 thin section R5228), early Serravallian, Rohožník, Slovakia, Vienna Basin; spermatangial conceptacle (arrow) roof and the pore are developed by filaments running parallel with the chamber; note adjacent bi/tetrasporic plant on the left margin of the figure. C. Carpogonial-carposporangial plant, NHM B1844 (thin section 6174), early Serravallian, Kamenica nad Hronom, Slovakia, Danube Basin. C 1. Encrusting growth form with prominent conceptacles projections (arrow); carpogonial conceptacle bear wide and long pore canal. C 2. Detail of the carpogonial conceptacle (arrow point to the pore canal); note cells projecting into it from the roofs. C 3. Another portion of the thallus with both, carpogonial (arrow) and carposporangial conceptacles; carposporangial conceptacle is large with pore canal cells projecting into the pore canal and the chamber.

phytes and gametophytes, thin section VEGA 184911435; spermatangial gametophyte, thin section VEGA 1849115451; bi/tetrasporophytes, thin sections VEGA 1849113351, VEGA 1849114051, and VEGA 1849114951; all from early Langhian, Lopadea Veche, Romania (Transylvania Basin).

Description.— Hydrolithon lemoinei occurs in infra- to circalittoral limestone beds ( Schaleková 1978; Seneš and Ondrejčíková 1991; Baráth 1992). Species overgrows coralline algae on the soft bottoms and rhodolith beds. It develops thin encrusting non-protuberant thalli ( Fig. 4A 1 ). Applanate branches have not been observed. Thallus surface is undulate with distinct projection of conceptacles. Individual thalli are 97–296 μm thick. Superimposed thalli develop 0.5 mm thick crusts. Thallus is pseudoparenchymatous with dorsiventral internal organisation and dimerous construction, consisting of the two systems of filaments ( Fig. 4A 2). Primigenous filaments consist of non-palisade cells 10– 21 μm H (mean ± SD: 15 ± 4.1 μm) and 12–30 μm L (mean ± SD: 22 ± 5.6 μm) (n = 10). Cells are square, flattened, or rectangular to polygonal. Polygonal cells are markedly larger and always produce two cells of postigenous filaments Fig. 4A 2). Postigenous filaments are multicellular and grow perpendicularly to primigenous ( Fig. 4A 2). However, short bistratose thallus could develop at the margins in young thallus probably. Filaments consist of square or rectangular to polygonal cell that could be of the same dimensions as primigenous filaments cells. Cells are 9–31 μm L (mean ± SD: 16 ± 6.4 μm) and 10–28 μm D (mean ± SD: 13 ± 5.2 μm) n = 11). Polygonal cells are enlarged and produce always two cells, the same as in primigenous filaments ( Fig. 4A 2). No alignment of cells was observed. Cells are laterally connected with fusions in both filaments. Meristematic cells are mostly longer than cells subtending them immediately and are 9–18 μm L (mean ± SD: 5 ± 0.5 μm) and 5–11 μm D mean ± SD: 8 ± 2.4 μm) (n = 5) ( Fig. 4A 3). Filaments terminate with single epithallial cell ( Fig. 4A 3).

Spermatangial conceptacles are triangular and developed from initials located peripheral to the fertile area ( Fig. 4B). Conceptacle is without central columella. Chamber is 71 μm in diameter and 18 μm in height. Pore canal is 37 μm H and 32 μm W at its base, tapering to the pore opening. Conceptacle protrude 43 μm above thallus surface and its external diameter reach 272 μm.

Gametophytes are dioecious, since carpogonial conceptacles develop on separate thallus than spermatangial Fig. 4C). They protrude 148 μm above thallus surface and external diameter reach up to 403 μm. The mode of formation is the same as in spermatangial. Chambers may have central columella. Chambers are 65 μm D and 41 μm H. Pore canal is markedly longer than in spermatangial conceptacles and is 103 μm L and 32 μm W. In thin section 6174 from Kamenica nad Hronom are carpogonial and carposporangial conceptacles documented in single plant. Carpogonial conceptacles are triangular and occasionally columellated, possessing broad pore canal ( Fig. 4C 2). Chambers are 54–108 μm D (mean ± SD: 77 ± 21.8 μm)

and are 23–43 μm H (mean ± SD: 31 ± 7.7 μm) (n = 6). Pore canals are long cylindrical. They are 72–123 μm L and 13– 50 μm W (n = 6). Carposporangial conceptacle chamber is 271 μm D and 69 μm H without central columella ( Fig. 4C 3). Bi/tetrasporangial conceptacles are uniporate and markedly protrude over the thallus surface ( Fig. 4A 4). They protrude up to 173 μm above thallus surface. External diameter is 372–393 μm (n = 2). Conceptacles were developed from initials peripheral and interspersed within sporangial initials, resulting in the more or less perpendicularly oriented roof cells to the chamber ( Fig. 4A 4). Pore lining cells were not observed. The roof is formed by cells narrower than postigenous and by polygonal cells producing two other cells also. Chambers are rounded to ellipsoid. They are 214–231 μm D (mean ± SD: 222 ± 12.1 μm) and 125–134 μm H (mean ± SD: 129 ± 6.3 μm) (n = 2). Chambers are not columellated. Pore canal is 83–102 μm L and up to 47 μm W.

Remarks.—Species was designated as Melobesia lemoinei by Miranda (1935). Later was reassessed by Aguirre et al. (2011) and positioned to the genus Hydrolithon because of the bi/tetrasporic conceptacle type, presence of lateral cells fusions and thallus construction. Bi/tetrasporophytes fit within the description provided by Aguirre et al. (2011) and gametophytes and carposporangial conceptacles bearing plants possess the same morpho-anatomical features as bi/ tetrasporophytes ( Table 5).

There is one character briefly discussed in revision of the type material—the pore canal anatomy. All of the studied plants, known plants ( Hrabovský et al. 2015: 464, fig. 16; Chelaru and Bucur 2016: 11, fig. 3c) and that ones with the type ( Aguirre et al. 2011: 283, fig. 6b) possess conceptacles with pore canals lined by cells projecting into the pore canal. This could be the result of either roof cells projections comparable to Pneophyllum , Neogoniolithon , Mastophora , and Spongites , or presence of papillae lining the pore canal found in Hydrolithon , Porolithon , Lithophyllum , and Titanoderma ( Irvine and Chamberlain 1994; Ringeltaube and Harvey 2000; Harvey et al. 2005, 2006; Basso and Rodondi 2006; Rösler et al. 2016). Given close similarity between the papillae ( Fig. 4A 4, left margin of pore canal) and the type of the conceptacle development, the second option is likely more. Whether the specimen is bi/tetrasporophyte is proved by distinct phases of the complete life cycle presence.

Prior to this study the two occurrences were reported from Slovakia: Lithophyllum (Dermatolithon) sp. ( Schaleková 1973: 218, pl. 74: 2) from Rohožník and Lithophyllum (Dermatolithon?) sp. ( Schaleková 1969: pl. 21: 2) from Sandberg. The first one represents H. lemoinei but the second one possesses thallus with cells laterally not joined with fusions. Schaleková (1969, 1973, 1978) referred only these two specimens, others from the remaining localities find in her collection during this study are unpublished therefore.

Species has been found in Transylvania, Novohrad, Danube, and Vienna basins. Also, it occurs in the early Langhian Carpathian Foredeep localities from Czech Republic ( Hrabovský et al. 2015) and Pinczów Limestone in Poland ( Studencki 1988a) but is missing in Maksymivka (Carpathian Foredeep). Occurrence in the early Serravallian Roztocze Hills algal-vermetid reefs documented by Pisera (1985) is not supported. There is another similar species reported under the names of Lithophyllum (Dermatolithon) nataliae possessing comparable morphological features with H. lemoinei found in the Poland ( Studencki 1988b: fig. 10; Studencki and Pisera 1989: pl. 12: 1, 2). The type of Lithophyllum (Dermatolithon) nataliae Maslov, 1956 was recently transferred by Bassi et al. (2005) to the extinct genus Karpathia Maslov, 1962 . This genus is characterized by: (i) dimerous thallus construction with (ii) cells laterally joined with fusions, (iii) fusion in postigenous filaments are more extensive, (iv) each ventral cell produce one or two cells of postigenous filaments, (v) cells are smaller in size towards the dorsal surface, and (vi) sporangial conceptacle is uniporate ( Bassi et al. 2005). Characters (iii) and (v) were not observed in H. lemoinei nor in the figured specimens from Polish Carpathian Foredeep. To the contrary, the examined specimens often terminate with elongated meristematic cells and single epithallial cell.

Geographical and stratigraphical range.—Oligocene to middle Miocene (early Serravallian) of the Mediterranean and central Paratethys.

Figures

Fig. 1. Modified geographical and geological map of the studied area with Recent distribution of central Paratethyan deposits, redrawn from Kováč (2000). List of studied sites: 1, Rohožník; 2, Vývrat; 3, Stupava; 4, Devínska Kobyla; 5, Wolfsthal; 6, Müllensdorf; 7, Mikulov; 8, Židlochovice; 9, Blučina; 10, Rebešovice; 11, Telnice; 12, Pratecký Vrch; 13, Holubice; 14, Vyškov; 15, Hluchov; 16, Přemyslovice; 17, Lomnice; 18,- Ochoz; 19, Kralice nad Oslavou; 20, Hostim; 21, Modrý Majer; 22, Čierny Hill; 23, Kamenica nad Hronom; 24, Pavlová; 25, Veľký Pesek; 26,- Sazdice; 27, Štúrovo; 28, Kosihovce; 29, Maksymivka; 30, Lopadea Veche; 31, Weglinek; 32, Zagrody.