Home of the Fossil Coralline Algae
CORALLINE RED ALGAE FROM THE UPPER EOCENE CALCARE DIE NAGO (LAKE GARDA, NORTHERN ITALY)
by Davide Bassi (Ferrara)
Bassi, D., 1998: Coralline Red Algae
(Corallinales, Rhodophyta) from the Upper Eocene Calcare di Nago (Lake Garda, Northern
Annali Universitá di Ferrara, vol. 7 (suppl.): 5-51.
Read an Abstract about the geological position of the Calcare di Nago
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PLEASE NOTE: DESIGNATION OF TAXONOMIC NAMES ARE USED ACCORDING TO THE ABOVE CITED PUBLICATION
Mesophyllum sp. 1
Spongites sp. 1
Spongites sp. 2
Spongites sp. 3
Neogoniolithon sp. 1
Neogoniolithon sp. 2
Lithoporella cf. minus
Mastophoroideae gen. et sp. indet.
Sporolithon cf. aschersoni
Sporolithon sp. 1
Geniculates sensu lato
Halimeda sp. 1
Division RHODOPHYTA Wettstein 1901
Class RHODOPHYCEAE Rabenhorst 1863
Order CORALLINALES Silva & Johansen 1986
Family Corallinaceae Lamouroux 1816
Subfamily Melobesioideae Bizzozero 1885
Lectotype species. Lithothamnion muelleri Lenormand ex Rosanoff 1866
Remarks. Woelkerling (1985b, 1988) proposed conservation of the homonym Lithothamnion Heydrich (1897) against Lithothamnium Philippi (1837).
According to Braga et al. (1993), diagnostic features of Lithothamnion are: thallus monomerous composed of numerous layers of cells, core filaments non-coaxial, cell fusions present, secondary pit absent, epithallial cells flat, epithallium one-cell thick, tetra/bisporangial conceptacles multiporate.
The characters that have been so far used in the delimitation of the fossil species (Tab. 3) were compared to those adopted for the Recent species both by Wilks & Woelkerling (1995) from the southern Australia and by Basso (1995) from the Tyrrhenian Sea (Mediterranean). This comparison has provided the following results. At least seven characters relating to vegetative features and one relating to reproductive ones have been used by previous authors to delimit fossil species of Lithothamnion (Tab. 3). Only one of these (plant habit, character 1) has been found useful in delimiting the Recent species as an ancillary character (Wilks & Woelkerling, 1995). The remaining characters are considered too variable (characters 2-8). Except for a few species, the numerical characters are thus not sufficiently reliable to discriminate the species, as already demonstrated for Neogene Lithophyllum (Braga & Aguirre, 1995). In the present-day species both from the Tyrrhenian Sea (Basso, 1995) and southern Australia (Wilks & Woelkerling, 1995), it seems that the diagnostic characters at species level are the shape and structure of the conceptacles (in particular those associated with tetra/bisporangial conceptacle roof anatomy).
Lithothamnion sp.1 [image]
1995a. Lithothamnion sp. 1; Bassi, pag. 87-88, pl. 1, figs. 1-2.
Morphology. Ranges from lumpy to encrusting plants, with protuberances reaching up to 2 mm long and 1-2.5 mm wide.
Vegetative anatomy. Dorsiventral organisation in crustose portion and radial in protuberances; core filaments non-coaxial, core portion about 50-75-100mm; cells 16-24 mm (M= 20, s.d. 4) long and 7-13 mm (M= 10, s.d. 3) in diameter; core filaments curve outwards towards the thallus surface. Peripheral region with cells 9-13 mm (M= 11, s.d. 2) long and 9-11 mm (M= 10, s.d. 1) in diameter. Cells of adjacent filaments connected laterally by fusions. Epithallial cells not preserved.
Tetra/bisporangial conceptacles multiporate; conceptacle chamber 586-604mm (M= 595, s.d. 9) in diameter and 182-198 mm (M= 190, s.d. 8) high; conceptacle roof protruding above or flush with surrounding thallus surface, 34-40 mm (M= 37, s.d. 3) thick, and composed of 9 cell layers, with cells 5 mm long and 5 mm in diameter; depth of tetra/bisporangial conceptacle chamber floor of about 10-12 cells. Pores diameter of 10-13 mm. All the conceptacles are buried in the thallus.
Remarks. L. sp. 1 shows analogies with Lithothamnium aesitante described by Francavilla et al. (1970) from the Priabonian of the Colli Berici, however, the authors did not illustrated the species except for a photos of the multiporate conceptacles, which are smaller than those of L. sp. 1. Bassi (1995a) sampled the same locality of Francavilla et al. (1970) and described L. sp. 1 which may be compared to L. sp. 1 herein described.
Lithothamnion sp.2 [image]
Morphology. Plants encrusting to foliose; rarely warty growth-forms with 1 mm long and less than 1 mm wide protuberances.
Vegetative anatomy. Dorsiventral organisation in crustose portion and radial in protuberances; core filaments non-coaxial, core portion 480-550mm thick; cells 8-12 mm (M= 10, s.d. 2) long and 22-25 mm (M= 23, s.d. 2) in diameter; core filaments curve outwards towards the thallus surface. Peripheral region with cells 7-11 mm (M= 9, s.d. 2) long and 7-9 mm (M= 8, s.d. 1) in diameter. Cells of adjacent filaments connected laterally by fusions. Epithallial cells not preserved.
Tetra/bisporangial conceptacles multiporate; conceptacle roof raising above thallus surface, 33-37mm (M= 35, s.d. 2) thick, composed of about 4 cell layers with cells 10 mm long and 1 mm in diameter; conceptacle chamber 510-530 mm (M= 520, s.d. 10) in diameter and 168-190 mm (M= 179, s.d. 11) high. Pore canal, about 5 mm in diameter and 35 mm high, is lined by filaments whose cells do not differ markedly from those of the surrounding roof.
Remarks. L. sp. 2 differs from L. sp. 1 in having smaller conceptacle chambers, higher pore canals, conceptacle roof raising above thallus surface and composed of about 4 cell layers.
Lectotype species: Mesophyllum lichenoides (Ellis) Lemoine 1928
Remarks. According to Braga et al. (1993), diagnostic features of Mesophyllum are: thallus momerous, coaxial core filaments, epithallium thin and unknown in fossil material, cell fusions, secondary pits absent, tetra/bisporangial conceptacles multiporate.
Mesophyllum is seems to be the only genus of the subfamily Melobesioideae with a "crustose to fruticose but not taeniform" growth-forms (pag. 390) and with "a predominantly coaxial core" (pag. 392, Woelkerling & Irvine, 1986; Woelkerling, 1988). Woelkerling & Harvey (1993) delimited Mesophyllum from other melobesioid genera on the basis of the anatomy of spermatangial conceptacles. However, all melobesioid species which have had a predominance of coaxial core, have been ascribed to Mesophyllum. This suggests that, while M. may not be designed only on the basis of a coaxial core, this character is strongly associated with the genus, and may be useful for identification when sexual material is not available, as is often the case with populations of M. species (Keats & Chamberlain, 1994; Keats & Maneveldt, 1997).
The coaxial core arrangement has thus been one of the most important features used in the fossil material to ascribe several specimens to the genus Lithophyllum. The lack of tetra/bisporangial conceptacles, and thus the impossibility to recognize the conceptacle roof characters (uniporate or multiporate) did not preclude the establishment of new species (Lemoine, 1928; Conti, 1950; Mastrorilli, 1968). The main difference in the vegetative anatomy between Lithophyllum and Mesophyllum is that the latter is characterized by cell fusions. According to the recognition of this cell characters, several fossil species previously identified as Lithophyllum, should be revised.
Mesophyllum sp. 1 [image]
1995a. Mesophyllum sp. 1; Bassi, pag. 88-90, pl. 1, fig. 4, text-fig. 8A.
Morphology. Plants foliose and commonly fruticose with cylindrical branches mostly 150mm in diameter and rare fragments of thin crusts.
Vegetative anatomy. Thallus monomerous; internal longitudinal organisation radial, composed by a single system of cell filaments that form a central coaxial core with arching tiers of cells when viewed in radial section; cells 27-32mm (M= 29, s.d. 3) long and 10-16 mm (M= 13, s.d. 3) in diameter in core region; main dimensions found in the axial part of the thallus. Distal portions of the filaments arch upwards towards the dorsal thallus surface or slant downwards towards the ventral thalus surface in varying degree; the cells of this portions are shorter (about 12 mm in diameter) than those in the coaxial core and usually micritized. No epithallial cells were recognized. Cells of adjacent filaments connected laterally by cell fusions. Conceptacles not found.
Remarks. The thallus monomerous with a central coaxial core together with cell fusions enable the specimens to be ascribed to Mesophyllum (see Woelkerling & Irvine, 1986; Keats & Chamberlain, 1994).
Among the Palaeogene species identified in the Piedmont Basin (Mastrorilli, 1968) and in Veneto (Mastrorilli, 1973; Francavilla et al., 1970; Vannucci, 1970), Lithophyllum simplex Lemoine 1927 and Lithophyllum symetricum Lemoine 1927 show analogies as far as the thallus organisation of M. sp. 1 is concerned. The descriptions of these species made by Mastrorilli (1968), Francavilla et al. (1970), and Vannucci (1970) report the dominant coaxial core filament arrangement of the thallus and the absence of conceptacles. Moreover, the illustration of the species show predominant cell fusions which thus enable the specimens to be identified as Mesophyllum and not as Lithophyllum.
Subfamily Mastophoroideae Setchell 1943
Genus Spongites Kützing 1841
Type species: Spongites fruticulosa Kützing 1841
Remarks. According to Braga et al. (1993), diagnostic features of Spongites are: core filament non-coaxial, cell fusions present, secondary pit absent, tetra/bisporangial conceptacles uniporate, pore canal of conceptacles bordered by cell filaments, subparallel to the roof surface and protruding into the canal.
In considering the relationships of Spongites with other Corallinaceae, Hydrolithon "presumably" differs from Spongites in possessing a unistratose rather than a multistratose core ("medullar hypothallium", Woelkerling, 1985a), and Neogoniolithon in having coaxial core filamments (Braga et al., 1993). Further discussions about the relationships between Spongites and H. have been provided by Penrose & Woelkerling (1992). At present, S. is delineated from Neogoniolithon by the absence of coaxial core filaments (Woelkerling, 1985a, 1988). It seems that reproductive, rather than vegetative, characters provide a basis for generic differentiation in the Mastophoroideae; vegetative characters may, however, often be of diagnostic value at species level (Chamberlain, 1993). The generic diagnosis proposed by Penrose (1992) and Penrose & Woelkerling (1992) are, therefore, accepted.
In most identification keys of fossil corallines the recognition of uniporate conceptacles and non-coaxial core filament ("plumose" arrangement) defined Leptolithophyllum and Tenarea (pag. 95-96, Conti, 1950) and sometime Lithophyllum (pag. 37-39, Lemoine, 1939). According to Woelkerling (1988), Leptolithophyllum is not recognized as a valid taxon (p. 103-104); Tenarea and Lithophyllum, both lacking cell fusions, belong to the subfamily Lithophylloideae.
Spongites sp. 1 [image]
Morphology. Encrusting (up to 2 mm in thickness) or warty with unbranched protuberances mostly 1.0 mm hight and 3-4 mm wide.
Vegetative anatomy. Thallus monomerous with non-coaxial cell filaments about 100-110mm in thickness, with cells 16-20 mm (M= 18, s.d. 2) high and 8-12 mm (M= 10, s.d. 2) in diameter. Peripheral region with cells 14-20 mm (M= 17, s.d. 3) high and 9-11 mm (M= 10, s.d. 1) in diameter; distinct growth rhythms; cell fusions connecting the contiguous filaments. Epithallial cells not found.
Tetra/bisporangial conceptacles uniporate with sub-cylindrical pores (Fig. 8); chambers are elliptical in shape, 92-118mm (M= 105, s.d. 13) high and 205-235 mm (M= 220, s.d. 15) in diameter; depth of tetra/bisporangial conceptacle chamber floor of 10-12 cells. Pore canal 100-104 mm (M= 102, s.d. 2) long and 33-37 mm (M= 35, s.d. 2) in diameter, lined by numerous small cells arranged in 12-14 filaments subparallel to the roof surface. The conceptacles are burried in the thallus.
Remarks. The core filament are non-coaxial, the occurrence of cell fusions, the tetra/bisporangial conceptacles uniporate, and the pore canal of conceptacles bordered by cell filaments subparallel to the roof surface and protruding into the canal allow to identify the genus Spongites. S. sp. 1 shows possible similarities with Lithophyllum malarodai Mastrorilli (1958) Lithophyllum lateporatum Mastrorilli (1973), and Lithophyllum vicetinum Mastrorilli (1973).
Mastrorilli (1958) defined L. malarodai, the type locality is Fontanafredda, Monti Lessini, Lutetian). Afterwards the same author recognized two new species in the Oligocene-Miocene deposits near Schio-Vicenza: L. lateporatum and L. vicetinum (1973). Their peculiar characters are represented by the conceptacle shapes: the arcuate conceptacle walls, the flat floors, and the long pore canal make analogies between these species. The schematic drawings and the photos of these species reported by Mastrorilli (1958, 1973) show uniporate conceptacles which are comparable to those of S. sp. 1. In the photos 2 and 3 of pl. 6 (Mastrorilli, 1973) showing L. lateporatum and L. vicetinum respectively, it is possible to recognize the growth rhythms of the thallus and the absence of a well defined separation of the cells; this latter is usually due to the fusions between them. The non-coaxial cell filaments, the cell fusions, and the uniporate conceptacles allow L. malarodai, L. lateporatum, and L. vicetinum to Spongites to be recognized. Nevertheless, no revision of the holotypes and the original collections was made thus far.
Spongites sp. 2 [image]
Morphology. Encrusting (usually 1.5 mm thick) or weakly warty in correspondence of conceptacles.
Vegetative anatomy. Monomerous thallus, about 60mm thick; cell filaments non-coaxial with cells 16-20 mm (M= 18, s.d. 2) high and mm 8-12 mm (M= 10, s.d. 2) in diameter. Peripheral cell filaments with cells 12-16 mm (M= 14, s.d. 2) high and 7-9 mm (M= 8, s.d. 1) in diameter; cell fusions occurring between cells of contiguous filaments; secondary pit connections not seen. Subepithallial and epithallial cells not found.
Tetra/bisporangial uniporate conceptacles from flask to bean shaped, raising above the thallus surface with the typical bell-form; chambers 150-170mm (M= 160, s.d. 10) high and 270-300 mm (M= 285, s.d. 15) in diameter. Pore canal conical in shape 200 mm high and about 50 mm in diameter; depth of tetra/bisporangial conceptacle chamber floor of 10 cells; central columella about 40-50 mm high. Only one uniporate conceptacle differs in shape and size from the others (Fig. 9); it is flask in shape with chamber 80 mm high and 540 mm in diameter; flat floor with marginal depressions about 30 mm depth. Pore canal about 240 mm high, 30 mm and 50 mm in diameter at the base and top respectively; cell filaments protruding into the canal.
Remarks. Spongites sp. 2 differs from Spongites sp. 1 in having larger conceptacle chambers and larger pore canals which are conical in shape.
Spongites sp. 3 [image]
Morphology. Encrusting plants up to 300-400 mm in thickness.
Vegetative anatomy. Monomerous thallus with non-coaxial cell filaments, 100-250mm thick; cells 31-39 mm (M= 35, s.d. 4) high and 18-22 mm (M= 20, s.d. 2) in diameter arranged in a regualr grid. Peripheral region with cells 31-39 mm (M= 35, s.d. 4) high and 19-21 mm (M= 20, s.d. 1) in diameter; cell fusions connecting the contiguous filaments. Epithallial cells not found.
Tetra/bisporangial conceptacles uniporate with subconical pores; chambers are flask shaped in section, 194-206mm (M= 200, s.d. 6) high and 463-477 mm (M= 470, s.d. 7) in diameter; depth of tetra/bisporangial conceptacle chamber floor of about 10 cells. Pore canal about 150 mm long and 80 mm in diameter, lined by numerous small cells arranged in 10-11 filaments subparallel to the roof surface.
Remarks. Spongites sp. 3 differs from S. sp. 1 in having larger conceptacle chambers and conical pore canals; S. sp. 3 difffers from S. sp. 2 in having larger conceptacles and shorter pore canals. S. sp. 3 show similarities with S. sp. described by Bassi (1995a) in the Priabonian of the Colli Berici, however, this latter has a larger conceptacle diameter than the S. sp. 3.
Genus Neogoniolithon Setchell & Mason 1943
Type species: Neogoniolithon fosliei (Heydrich) Setchell & Mason 1943
Remarks. According to Braga et al. (1993), diagnostic features of Neogoniolithon are: core filament coaxial, cell fusions present, secondary pit absent, tetra/bisporangial conceptacles uniporate, pore canal of conceptacles bordered by cell filaments, subparallel to the roof surface and protruding into the canal. Neogoniolithon differs from Spongites in possessing a coaxial core arrangement. Further remarks have been above reported.
Neogoniolithon sp.1 [image]
Morphology. Encrusting plants up to 1 mm in thickness; the rare fertile crusts are characterized by weakly developed protuberances as high as the conceptacles.
Vegetative anatomy. Thallus monomerous; internal longitudinal organisation radial, composed by a single system of cell filaments forming a central coaxial core, about 200-250mm in thickness; cells 21-29 mm (M= 25, s.d. 4) high and 13-17 mm (M= 15, s.d. 2) in diameter. Distal portions of the filaments with cells 15-19 mm (M= 17, s.d. 2) high and 8-12 mm (M= 10, s.d. 2) in diameter. Cell fusions connecting the contiguous filaments. Epithallial cells not found.
Tetra/bisporangial conceptacles uniporate with conical pores and raising above the thallus surface; chambers are flask in shape, 180-200mm (M= 190, s.d. 10) high and 740-780 mm (M= 760, s.d. 20) in diameter; depth of tetra/bisporangial conceptacle chamber floor of about 15 cells. Pore canal 160-200 mm long and 60-70 mm in diameter, lined by numerous small cells arranged in filaments subparallel to the pore canal.
Neogoniolithon sp. 2 [image]
Morphology. Encrusting and layered growth-forms, with thallus thickness up to 500mm.
Vegetative anatomy. Thallus monomerous; internal longitudinal organisation radial, composed by a single system of cell filaments that form a central coaxial core, about 200mm in thickness; cells 21-33 mm (M= 27, s.d. 6) high and 11-13 mm (M= 12, s.d. 1) in diameter. Distal portions of the filaments with cells 13-19 mm (M= 16, s.d. 3) high and 8-12 mm (M= 10, s.d. 2) in diameter. Cell fusions connecting the contiguous filaments. Epithallial cells not found.
Tetra/bisporangial conceptacles uniporate; only two tangential section of conceptacles were found; they show typical uniporate chambers which are respectively 230-250mm high and 460-480 mm in diameter. The random sections do not show the pore canal.
Remarks. N. sp. 2 differs from N. sp. 1 in having a thicker peripheral region, higher and with different shape conceptacles.
The thick coaxial core reminds those of Lithophylum contii Mastrorilli s.a. (pls. 25-26; Fravega & Vannucci, 1987) and of Lithophyllum giammarini described by Vannucci (1970) (Lithophyllum giammarinoi is considered a junior synonym of Lp. contii; Fravega & Vannucci, 1987). No recent revision of the type collections of these species has been made so far.
L. contii Mastrorilli is characterized by a thick core in which cell fusions connecting the contiguous filaments are present. They have never been described by the several authors who studied this species (Mastrorilli, 1967, 1968; Vannucci, 1970; Francavilla et al., 1970; Fravega & Vannucci, 1987), however, it is possible to recognize them in the photos 2 and 4 of pl. 25 representing the original types (in Fravega & Vannucci, 1987). The conceptacles of N. sp. 2 were always recorded in tangential sections which do not show the pore canals. The shape and the size of these conceptacles are, however, comparable to those reported by Fravega & Vannucci (1987), who affirm that "i concettacoli in sezione tangenziale appaiono come cavit ovoidali di dimensioni minori (rispetto alla sezione assiale; n.d.r.) (35-90mm x 160-200 mm)". The occurrence of cell fusions characterize the members of the subfamilies Melobesioideae and Mastophoroideae; moreover, the presence of uniporate conceptacles is typical of the mastophoroid genera (Braga et al., 1993). The types of Lithophyllum contii need thus to be revised and eventually reassigned to a different genus (Neogoniolithon?).
(Foslie) Foslie 1909
Type species: Lithoporella melobesioides (Foslie) Foslie 1909
Remarks. According to Braga et al. (1993) and Woelkerling (1988), diagnostic features of Lithoporella are: thin dimerous thallus with large cells, presence of cell fusions, and uniporate tetra/bisporangial conceptacles. The dimerous thallus consists of multiple overgrowths of large cells.
Lithoporella melobesioides (Foslie) Foslie 1909 [image]
1950. Lithoporella melobesioides (Foslie); Johnson & Ferris, pag. 18-19, pl.
8, fig. A.
1958. Lithoporella melobesioides Foslie; Mastrorilli, pag. 17.
1968. Lithoporella melobesioides (Foslie) Foslie; Mastrorilli, pag. 376-378, pl. 39, fig. 5.
1970. Lithoporella melobesioides (Foslie) Foslie; Vannucci, pag. 472-474, pl. 9, figs. 1-2.
1977. Lithoporella melobesioides (Foslie) Foslie; Buchbinder, pag. 428- 430, pl. 6, figs. 2-3, 5.
1983d. Lithoporella melobesioides (Foslie) Foslie; Bosence, pag. 165-166, pl. 18, fig. 2, text-fig. 11.
Morphology. Encrusting growth-forms, single or multiple overgrowths of cell filaments (up to 400mm in thickness).
Vegetative anatomy. Dimerous plants with primigenous filaments with palisade cells 33-43 mm (M= 38, s.d. 5) high and 21-27 mm (M= 24, s.d. 3) in diameter. Postigenous filaments restricted to the fertile portions of the plants. Cell fusions present.
Rare tetra/bisporangial uniporate conceptacles, 170-188mm high and 352-400 mm in diameter, with pore canal about 100 mm high and 70 mm in diameter.
Remarks. most species of Lithoporella recorded from the Eocene to the Recent were assigned to melobesioides (which is also the type species of the genus). This species is well known both in the fossil (Cretaceous) and Recent material.
Lithoporella cf. minus Johnson, 1964b [image]
1950. Lithoporella sp.?; Johnson & Ferris. pag. 19, pl. 3, fig. C.
1968. Lithoporella minus Johnson; Mastrorilli, pag. 378-379, pl. 39, figs. 6-7.
Morphology. Encrusting growth-forms, usually single or double overgrowths of cell filaments.
Vegetative anatomy. Dimerous plants with primigenous filaments with palisade cells 23-27mm (M= 25, s.d. 2) high and 11-15 mm (M= 13, s.d. 2) in diameter. Postigenous filaments restricted to the fertile portions of the plants. Cell fusions present.
Only two uniporate conceptacles were found; they are 130mm high and 200 mm in diameter in tangential sections; no measures of the pore canal were taken.
Remarks. L. cf. minus differs from L. melobesioides only in having smaller cells. Although there is high intraspecific variability, the thallus characters described above allow the comparison of our specimens to L. minus which has been always recorded in Eocene deposits to be made. The separation between these two species, however, is based only on the cell sizes (Johnson, 1964b), which does not seem a valid character at species level. A revision of L. minus together with the other species described in fossil material, and an account of L. melobesioides are needed.
Mastophoroideae gen. et sp. indet. [image]
1995b. Hydrolithon sp.; Bassi, pag. 20, figs. 6 A-B.
1996. Hydrolithon sp.; Bassi, pag. 146, pl. 17, figs. 1-5.
Morphology. Growth-form encrusting.
Vegetative anatomy. Monomerous thallus with cell filaments dorsiventrally arranged, core filaments 50-170mm thick; cells 13-17 mm (M= 15, s.d. 2) high and 8-12 mm (M= 10, s.d. 2) in diameter. Peripheral cell filaments with cells 22-28 mm (M= 25, s.d. 3) high and 12-20 mm (M= 16, s.d. 4) in diameter; poligonal-subexagonal shaped in transversal section; cell fusions connecting the contiguous filaments. Epithallial cells not found.
Tetra/bisporangia conceptacles not found.
Remarks. According to Braga et al. (1993), the occurrence of cell fusions characterizes the members of the subfamilies Mastophoroideae and Melobesioideae. As no conceptacles were found in the specimens above described, it is impossible to infer them to any genus. Large poligonal cells, as described for our specimens, were considered to belong to Hydrolithon by Martn et al. (1993). According to Penrose & Woelkerling (1992), the diagnostic features which distinguish Hydrolithon and Spongites are restricted to the pore canals of tetrasporangial conceptacles. Hydrolithon is characterized by conceptacles lined by a ring of elongate cells that arise from filaments interspersed amongst sporangial initials; they do not protrude into the canal, and are oriented more or less perpendicularly to the roof surface. For the relationships to Spongites, see the above mentioned remarks.
The absence of the tetra/bisporangial conceptacles in our specimens, however, does not allow a certain taxonomic determination at genus level to be made. Further studies concerning the conceptacle characters are thus needed.
Family Sporolithaceae Verheij 1993
Genus Sporolithon Heydrich 1897
Type species: Sporolithon ptychoides Heydrich 1897
Remarks. According to Braga et al. (1993), diagnostic features of Sporolithon are: thallus monomerous, core filaments non-coaxial, epithallium thin and unknown in fossil, tetrasporangia in sori.
According to ICBN rules, Woelkerling (1988) and Moussavian & Kuss (1990) have definitively demonstrated and accepted the priority of Sporolithon Heydrich 1897 over Archaeolithothamnium Rothpletz 1891/Archaeolithothamnion Rothpletz 1891 ex Foslie 1898. This priority is justified by article 34.1 of ICBN (Moussavian & Kuss, 1990). Verheij (1993) defined the new family Sporolithaceae. Braga et al. (1993) and Verheij (1993) affirm that cell and tetrasporangial sizes are not sufficient enough to identify a species. Cell sizes are not specific characters in Sporolithon (Verheij, 1993). Some anatomical characters, pointed out by Verheij (1992) as having value at species level, are not preservable in the fossil material. However, the number of additional cell filaments between tetrasporangia, the number of cells in the paraphyses, the basal layer of elongated cells, and the size of the tetrasporangia may be recognized in the fossil specimens (Bassi, 1995b; Braga & Aguirre, 1998).
Sporolithon cf. aschersoni (Schwager) Moussavian & Kuss, 1990 [image]
1883. Lithothamnium aschersoni Schwager, pag.147, pl. 29, figs. 25 a-e.
1898. Archaeolithothamnion aschersoni (Schwager) Foslie, pag. 3.
1990. Sporolithon aschersoni (Schwager) Moussavian & Kuss, pag. 934-936, pl. 1, figs. 1-5.
1995a. Sporolithon sp.; Bassi, pag. 90-91, pl. 1, fig. 7.
1995b. Sporolithon aschersoni (Schwager) Moussavian & Kuss; Bassi, pag. 14-19, figs. 3-5.
1996. Sporolithon aschersoni (Schwager) Moussavian & Kuss; Bassi, pag. 136-141; pl. 7, figs. 1-6; pl. 8, figs. 1-3; pl. 9, figs. 1-3; pl; 10, figs. 1-3; pl. 11, figs. 1-4.
Morphology. Lumpy, warty, and more rarely encrusting (mean thick up to 1 mm) plants, with typically swollen protuberances up to 1 mm long and 2 mm in diameter.
Vegetative anatomy. Monomerous plants with non-coaxial core of cell filaments, up to 100-160 mm in thickness; cells 13-17 mm (M= 15, s.d. 2) high and 10-14 mm (M= 12, s.d. 2) in diameter. Peripheral region much thicker than the ventral one; cells 16-20 mm (M= 18, s.d. 2) high and 8-12 mm (M= 10, s.d. 2) in diameter. Cell of adjacent filaments, commonly arranged in undistinct rows, are joined by cell fusions and primary pit-connections; growth-rhythms occur. No epithallial and initial cells were found.
Tetrasporangia occur within surface sori which are subcircular in shape and of indefinite size. Sori raise from a basal layer of elongated cells, 20-26mm (M= 23, s.d. 3) high and 8-10 mm (M= 9, s.d. 1) in diameter. Sori normally become buried within the thallus. Tetrasporangia, ellipsoidal in shape, are 57-73 mm (M= 65, s.d. 8) high and 30-34 mm (M= 32, s.d. 2) in diameter. Approximately 4-5-celled paraphysial filaments developed from subterminal initials and are interspersed between tetrasporangia.
Remarks. By bibliographical revision of the Palaeogene Italian species of Sporolithon, some anatomical similarities among the following species can be recognized: Sporolithon (Archaeolithothamnion) aschersoni (Schwager) Moussavian & Kuss (1990), A. lugeoni Pfender (1926), A. praeerithraeum Airoldi (1932), A. johnsoni Mastrorilli (1958), A. bericum Mastrorilli (1973), A. fabianii Mastrorilli (1973), A. poleoense Mastrorilli (1973), Sporolithon sp. (Bassi, 1995b). Characters considered to be diagnostic at the species level by phycologists (Verheij, 1992, 1993; Townsend et al., 1995) have been described for none of the species listed above, as they have not been recognized as significant by the authors (Schwager, 1883; Airoldi, 1932; Mastrorilli, 1958, 1973). The value of these diagnostic characters and their comparison regarding S. aschersoni have been discussed by Bassi (1995b).
Sporolithon sp. 1 [image]
Morphology. Lumpy and warty plants with swollen protuberances up to 2.5 mm long and 3 mm in diameter.
Vegetative anatomy. Monomerous plants with non-coaxial core of cell filaments, up to 40-50mm in thickness; cells 14-18 mm (M= 16, s.d. 2) high and 8-12 mm (M= 10, s.d. 2) in diameter. Peripheral region much more thicker than the ventral one; cells 17-23 mm (M= 20, s.d. 3) high and 8-12 mm (M= 10, s.d. 2) in diameter. Cell of adjacent filaments, commonly arranged in undistinct rows, are joined by cell fusions and primary pit-connections; growth-rhythms occur. No epithallial and initial cells were found.
Tetrasporangia grouped in sori as parallel lines (generally twin lines) of indefinite size. Sori do not raise from a basal layer of elongated cells. Sori normally become buried within the thallus. Tetrasporangia, ellipsoidal in shape, are 112-122mm (M= 117, s.d. 5) high and 29-33 mm (M= 32, s.d. 3) in diameter. No celled paraphysial filaments are interspersed between tetrasporangia.
Remarks. S. sp. 1 occurs only in the samples CNB94-97b, CNB94-103, CNB94-104. S. sp. 1 differs from S. cf. aschersoni in having larger tetrasporangia arranged in parallel lines which form the sori, and the absence of a basal layer of elongated cells below the tetrasporangia. According to the direct comparison between S. sp. 1 and the descriptions and illustrations of the Sporolithon ("Archaeolithothamnium" auct.) species sofar recorded in the Tertiary Piedmont basin and Veneto, any of these latter show tetrasporangia which do not raise from a basal layer of elongated cells. It is thus needed a revision of the types to verify the absence/presence of this and others anatomical features.
Geniculates sensu lato [image]
1995b. Corallina sp.; Bassi, pag. 20-21, fig. 6C.
1996. Corallina sp. 1; Bassi, pag. 152, pl. 24, figs. 5-6; pl. 25, figs. 1-5.
1996. Jania cf. nummulitica Lemoine, 1927; Bassi, pag. 152-153, pl. 25, fig. 6.
Morphology. Arborescent branching with dichotomous thalli.
Description: Fragments of thalli about 1.5 mm long and mainly 240-300mm in diameter. Rare genicula, approximately 130 mm long and 160 mm in diameter, with one row of cells very long, 8-9 mm (M= 8, s.d. 0.5); no cell fusion recognized. Intergenicula, 500 mm long and about 230 mm in diameter, with core cells 91-111 mm (M= 101, s.d. 10) long and 8-10 mm (M= 9, s.d. 1) in diameter; intergenicular cortication with cells 12-15 mm in diameter and 16-30 mm (M= 23, s.d. 7) long; sub-pentagonal/exagonal cells in transversal sections; cell fusions present. Conceptacles not found.
Remarks. The occurrence or absence of genicula is considered to informally divide the Corallinaceae into the geniculate (articulated) and nongeniculate (non-articulated) groupings. The genicula consist of a single uncorticated and uncalcified tiers or layers of core cells, which can be characterized by secondary pit-connections, lateral cell fusions, lateral branches, and cortications (Johansen & Silva, 1978; Woelkerling, 1988). Spores grow within conceptacles which, however, occur externally or in non-calcified portions of the thallus. Species of geniculate coralline algae are distributed worldwide in tropical and subtropical oceans (Dawson, 1966; Riosmena-Rodriguez & Siqueiros-Beltrones, 1996). The true number of geniculate coralline species is still controversial (Johansen, 1981; Kim, 1990; Riosmena-Rodriguez & Siqueiros-Beltrones, 1996). Taxonomic problems arise when only traditional methods of morphological comparison are used because of the phenotypic plasticity of geniculate species. The taxonomy of geniculate corallines has been based on growth-form, method of branching, internal and external characters of the genicula and intergenicula, and characters of the reproductive structures (Bressan, 1974; Johansen & Silva, 1978; Norris & Johansen, 1981; Woelkerling, 1988; Riosmena-Rodriguez & Siqueiros-Beltrones, 1996).
Geniculate corallines are abundant in many of the Cenozoic carbonate deposits, at places contributing importantly to the total bulk of the rocks. Difficulty in their study arises mainly from the fact that the classification at genus level of Recent representatives is based largely on the genicular cell characters and position and nature of conceptacles. As the genicula are generally not preserved, it has not been possible so far to apply the systematics of the present-day geniculates. A distinction between the fossil specimens of geniculate coralline genera has been proposed by Johnson & Ferris (1950) and Johnson (1964a) (see also Lignac-Grutterink, 1943), but without the possibility to distinguish genicular and intergenicular cells nor conceptacles.
Due to the absence both of decalcified genicula and conceptacles in our studied fossil material, we include all the geniculate fragments in the present "Geniculate corallines sensu lato" group, with any distinction of species and genera.
Subclass Florideophycidae Schmitz in Engler 1892
Order Cryptonemiales Schmitz in Engler 1892
Family Peyssonneliaceae Denizot 1968
Genus Polystrata Heydrich
Type species: Polystrata dura Heydrich 1905
Remarks. Trauth (1918) ascribed specimens recorded from the Eocene of Radstadt (Pongau, Austria) to the genus Lithothamnium as they shown a cell arrangement "Lithothamnium-type". Pfender (1936) described a crustose organism from the Cretaceous and Eocene of Europe, Egypt, and Turkey as Pseudolithothamnium album. Massieux & Denizot (1964) compared the genus Ethelia Weber van Bosse, 1913 to Pseudolithothamnium Pfender, 1936 and concluded that Ethelia was a synonym of Pseudolithothamnium. Denizot (1968), however, redefined the genus Ethelia as a previously designed genus Polystrata Heydrich, 1905. Buchbinder & Halley (1985, p. 254) recognized Polystrata alba (Pfender) Denizot and affirmed that 'squamariacean' rhodoliths from middle Eocene of Tonga Island are composed only of this algal species. Moussavian (1988) does not recognize the synonymy among Pseudolithothamnium, Ethelia and Polystrata because the type-species of these genera are very similar but not identical (p. 99). Reports of Polystrata alba (=Pseudolithothamnium album) were published by other authors (Segonzac, 1961; Beckmann & Beckmann, 1966; Vannucci, 1970; Moussavian, 1984, 1988). The taxonomy of Polystrata is discussed in detail by Massieux & Denizot (1964; =Ethelia), Moussavian (1988; =Pseudolithothamnium), and Bassi (1997).
Polystrata alba (Pfender) Denizot, 1968 [image]
1918. Lithothamnium torulosum Gmbel; Trauth (pars), pag. 213, pl. 1, figs.
1936. Pseudolithothamnium album nov gen. nov. sp., Pfender, pag. 304-308, pl. 19, figs. 1-5.
1961. Pseudolithothamnium album Pfender; Segonzac, pag. 445-446, pl. 13a, figs. 1, 2; text-pl., fig. 15.
1964. Ethelia alba (Pfender, 1936) Massieux & Denizot, pag. 31-42, pl. 1, figs. 1-10; pl. 2, fig. 1-5.
1968. Squamariacea; Mastrorilli, pl. 41, fig. 2.
1970. Polystrata alba (Pfender) Denizot; Vannucci, pag. 475-476, pl. 9, fig. 4.
1973. Polystrata; Mastrorilli, text-fig. 3.
1984. Ethelia alba (Pfender); Moussavian, pl. 2, fig.1; pl. 3, fig. 1.
1985. Ethelia alba (Pfender); Hfling, pag. 24, pl. 3, fig. 2.
1985. Polystrata alba (Pfender); Buchbinder & Halley, figs. 3, 6, 7, 8, 9.
1988. Pseudolithothamnium album Pfender; Moussavian, pag. 100-101, pl. 2, figs. 2-3.
1992. Pseudolithothamnium album Pfender; Darga, pag. 50, pl. 4, fig. 1; pl. 19, fig. 2.
1994. Pseudolithothamnium album Pfender; Rasser, pag. 199, pl. 2, fig. 5; pl. 3, figs.5, 6.
1995. Polystrata alba (Pfender); Masse, pag. 304, pl. 1, fig. 11.
1996. Pseudolithothamnium album Pfender; Bassi, pag. 153-155; pl. 26, figs 1-5; pl. 27, figs 1-2.
1997. Polystrata alba; Bassi, pag. 311-315, figs. 1-4b.
Morphology. Plants have irregularly layered to foliose growth-forms; numerous superimposed encrusting layers can develop into sub-ellipsoidal and sub-discoidal laminated nodules (= rhodoliths). The cavities between each layer may be filled with micrite.
Vegetative anatomy. Epigenous plant with pseudoparenchymatous thallus, composed of filaments and organized in a bilateral-radial manner in longitudinal section. In longitudinal section, each thallus (400-500mm thick) consists of a single eccentric row (closer to the ventral part of the crustose thallus) of primigenous filaments composed of tall cells, 47-57 mm (M= 52, s.d. 5) long and 28-36 mm (M= 32, s.d. 4) in diameter. Postigenous filaments arise plumosely from the outer surface of the cells of primigenous filaments both upward and downward; the dorsal ones bend progressively upward to become perpendicular to the surface of the thallus. The postigenous filaments are characterized by columnar cells, 35-41 mm (M= 38, s.d. 3) long and 9-15 mm (M= 12, s.d. 3) in diameter, dividing outwards, which reduce their sizes near the outer part of the thallus. Within a primigenous filament, all the successive cells are joined by primary pit-connections. Successive cells of postigenous filaments are joined by primary pit-connections. No secondary pit-connections in postigenous filaments have been recognized in the samples studied. Epithallial cells smaller than those below. Conceptacles not found.
Remarks. According to the original descriptions of the type species, the vegetative anatomy of Pseudolithothamnium album Pfender 1936, Polystrata alba (Pfender) Denizot 1968 and Ethelia alba (Pfender) Massieux & Denizot, 1964 have similar vegetative anatomies. All the three type species show a dimerous constructional system characterized by primigenous filaments from which the postigenous ones rise outwards. It follows that the three species are synonyms belonging to the oldest genus Polystrata Heydrich 1905. Thus, Polystrata alba (Pfender) Denizot, 1968 is the only valid name (Bassi, 1997).
A widespread Paleocene-Eocene limestone facies consisting predominantly of rhodoliths composed of peyssonneliaceans and nongeniculate corallines is known from the Southern Alps (Mastrorilli, 1968, 1973; Vannucci, 1970; Bassi, 1996), Apennines (Praturlon, 1966; Crescenti et al., 1969; Pignatti, 1994), Tonga (southwestern Pacific; Buchbinder & Halley, 1985), Northern Calcareous Alps and Helveticum (Darga, 1992), southern Slovenia (Jurkovsek et al., 1996), and Central Alpine Krappfeld Gosau (Rasser, 1994).
Division Chlorophyta Papenfuss, 1946
Class Chlorophyceae Ktzing, 1843
Family Halimedaceae Link, 1832
Genus Halimeda Lamouroux, 1812
Remarks. The largest living green marine algae belong to the order Bryopsidales, formerly Siphonales, and of the modern algae they are the least known. Six genera out of a total of twenty-four calcify. Five of the taxa, namely Halimeda Lamouroux, Penicillus Lamarck, Rhipocephalus Ktzing, Tydemania Weber van Bosse, and Udotea Lamouroux have been assigned to the family Halimedaceae; Pedobesia MacRaild & Womersly has been placed in the family Bryopsidaceae (Hillis-Collinvaux, 1984). Assignment to these families is based principally on differences in morphology, reproduction and distribution, although the data available for some genera are still very limited Hillis, 1991).
Mu (1991) considers the fossil specimens of Halimeda to belong to the family Udoteaceae, by accepting the classification of Bassoulet et al. (1983). This author discusses the relationships between Udoteaceae (= Halimedaceae in Hillis, 1991) and Gymnocodiaceae, and affirms that the erected fossil specimens of the Udoteaceae group have similar growth-forms, vegetative features, palaeoecological and geographical distribution of those of the Gymnocodiaceae.
It is evident that problems in determining the systematic position and classification of Gymnocodiaceae and fossil Udoteaceae are the result of the inadequate information available regarding the fossil material. In studying fossil calcareous algae we are not dealing with complete plants, but only with their calcareous skeletons which are generally in the form of moulds. According to the data presented by Hillis (1991) and other works about Bryopsidales (International Symposium, Alpine Algae 1993), it is possible to ascribe the fossil specimens of Halimeda to the family Halimedaceae.
Halimeda sp. 1 [image]
Morphology. Irregularly segments, 4-5 mm in lenght and about 0.5 mm in diameter, of arborescent to discoid (catenulate, sensu Hillis, 1991) plants.
Vegetative anatomy. Medullar portion of the thallus composed of few filaments (40-45mm in diameter) subparallel to the axis of the thallus. Irregularly arranged pores on the outer surface are approximately 30 mm in diameter. Reproductive organs not found.
Remarks. According to Flgel (1988) and Mu (1991), reliable species determination is rather difficult because of the great variability of Recent and fossil species.