Published: Rasser and Piller (in press: 1999): Journal of Micropalaeontology
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Created by Michael Rasser (17. Apr 01)
Subfamily MASTOPHOROIDEAE Setchell, 1943 Diagnosis: Tetra/bisporangial conceptacles uniporate, cell fusions present (Woelkerling, 1988).
Genus Lithoporella (Foslie) Foslie, 1909 Diagnosis: Non-endophytic dimerous thallus which lacks haustoria; primigenous filaments composed of palisade cells; thallus 2-3(-5) cells thick; tetra/bisporangial conceptacles lack a columella; conceptacle roof formed by filaments interspersed between sporangia; postigenous filaments are restricted to branching zones and conceptacle walls (Woelkerling, 1988). Braga et al. (1993) characterise Lithoporella by a thin thallus and multiple overgrows of large primigenous cells.
Remarks: Lithoporella is well known in fossil material and can be easily identified by its unistratose thallus with large cells.
Lithoporella melobesioides (Foslie) Foslie, 1909
1909 Lithoporella melobesioides (Foslie) Foslie: 59.
1957 Lithoporella melobesioides (Foslie) Foslie; Johnson: 234, pl. 37, fig. 5; pl. 43, figs 1-2; pl. 49, fig. 4. -
1982 Lithoporella melobesioides (Foslie) Foslie; Turner & Woelkerling: 218 ff., figs 2, 4, 6, 7-11, 15-17, 20, 21, 25, 26.
1994 Lithoporella melobesioides (Foslie) Foslie; Rasser: 198, pl. 3, fig. 3.
Description: Growth form encrusting, either forming single thalli or multiple overgrows.
Primigenous filaments show cell fusions. Cell length 11-20 Ám (M=17, SD=3), cell height 27-54 Ám (M=42, SD=9).
Postigenous filaments occur around the tetra/bisporangial conceptacle chambers only (pl. 1, fig. 1), trichocytes absent. Epithallus not preserved.
Tetra/bisporangial conceptacles completely raised above the thallus surface. Filaments around the conceptacle pores are subparallel to the outer roof surface. Length of cells in the conceptacle roof 14-36 Ám, diameter 9-25 Ám. Cells near the outer conceptacle roof surface usually longer than at the inner surface. Height of conceptacles: 130-180 Ám, diameter: 410-420 Ám. Pore length 160 Ám, diameter 110 Ám. Type of conceptacle roof formation unclear. Sexual conceptacles and carposporangia unknown.
Remarks: L. melobesioides is one of the few species which is well known both in Recent and in fossil material. Nevertheless, it has to be treated carefully, as the status of most species in Lithoporella is uncertain (Woelkerling, 1988). This species is not abundant in the studied material. It overgrows corals and other coralline algae. Measured sample: MOL25.
Genus Neogoniolithon Setchell & Mason, 1943 Diagnosis: Thallus non-endophytic, lacking haustoria and palisade cells; core filaments coaxial (Woelkerling, 1988; Braga et al., 1993). Penrose (1992) and Penrose & Chamberlain (1993) define Neogoniolithon mainly by simple (i. e., unbranched) spermatangial initials (compare text-fig. 2I) which are borne on both the floor and roof of the conceptacles and gonimoblast filaments arising dorsally from fusion cells.
Remarks: The separation of Spongites from Neogoniolithon using the arrangement of core filaments (Braga et al., 1993) is not accepted in present-day taxonomy which uses the structures of sexual reproductive organs instead (Penrose, 1992; Penrose & Chamberlain, 1993). Nevertheless, Neogoniolithon is the only genus of the Mastophoroideae with coaxial core filaments (Woelkerling, 1988).
Description: Growth form encrusting to layered and foliose, tips of lamellate branches may fuse together. Thallus usually 700 Ám thick, but at the conceptacle bearing portions is up to 1.4 mm.
Core portion 250-400 Ám thick. Filaments curve towards both the ventral and dorsal thallus surfaces (pl. 1, fig. 2). Cell fusions are abundant (pl. 1, fig. 4). Cell length 25-41 Ám (M=31, SD=5), diameter 11-18 Ám (M=13, SD=2).
Peripheral filaments are usually restricted to the dorsal surface but may sometimes additionally occur on the ventral thallus portion (pl. 1, fig. 2). Peripheral portion 150-250 Ám thick, no growth rhythms. Cell fusions occur, trichocytes absent. Cell length 9-16 Ám (M=12, SD=2), diameter 7-11 Ám (M=9, SD=1). Epithallial cells not preserved.
Tetra/bisporangial conceptacles: height 190-200 Ám, diameter 600-620 Ám. Pore length 144-190 Ám, diameter 65-68 Ám. Conceptacle floor 3-4 cell layers below thallus surface. Cell length of cells in the conceptacle roof 18-25 Ám (M=21, SD=3), diameter 9-13 Ám (M=11, SD=1). Filaments around the conceptacle pore subparallel to the conceptacle roof (pl. 1, fig. 3). No columella found. Type of conceptacle roof formation unclear, but appear not to be formed by filaments enclosing the conceptacle chamber (pl. 1, fig. 3). Sexual conceptacles and carposporangia were not seen.
Remarks: Traditionally (Wray, 1977) this genus would have been identified as Lithophyllum Philippi (1837) because cell fusions were not recognised in fossil material prior to the 1990's (Bosence, 1990; Braga et al., 1993).
Only uniporate conceptacles without preserved reproductive organs were found in the studied material. It is not known if these are tetra/bisporangial (asexual) or gametangial (sexual) conceptacles. If they are gametangial conceptacles, which are always uniporate, the described genus may have multiporate tetra/bisporangial conceptacles which are not preserved in the studied material. Owing to the regular coaxial thallus, the described genus in this case would belong to Mesophyllum (although the coaxial core is no longer diagnostic for Mesophyllum Lemoine (1928) we apply the same arguments as for Neogoniolithon). If, however, the identified uniporate conceptacles are gametangial conceptacles of Mesophyllum, they would have to be formed from filaments which enclose the chamber (Woelkerling & Harvey, 1993). Owing to the filament structure in the walls of the identified conceptacles, this kind of formation can be excluded. We therefore refer this species to Neogoniolithon. Besides Phymatolithon sp., Neogoniolithon sp. is one of the most abundant species in the studied material. It forms coralline algal bindstones in association with the latter and occurs fragmented in most samples. Measured sample: MOL110.
Genus Spongites KŘtzing, 1841 Diagnosis: Non-endophytic thallus which lacks haustoria; thallus organisation dimerous or monomerous; dimerous thallus portions lacking palisade cells; filaments around the conceptacle pore canals subparallel to the roof surface (Penrose & Woelkerling, 1992). Braga et al. (1993) additionally mentioned the presence of non-coaxial core filaments to separate Spongites from Neogoniolithon.
Remarks: Hydrolithon (Foslie) Foslie (1909) was considered to be congeneric with Spongites by Woelkerling (1988). Penrose & Woelkerling (1992), however, showed that both genera can be separated by the filament arrangement in the conceptacle roof. As it was shown by Braga et al. (1993) and by the current study this character can be applied to fossil material as well. The separation from Neogoniolithon is discussed above.
Spongites sp. 1
Description: Growth form encrusting, thallus organisation dimerous.
Primigenous filaments unistratose, cell size variable. Cell length 18-40 Ám (M=31, SD=9), diameter 9-22 Ám (M=13, SD=4).
Postigenous filaments show cells with irregular cell walls, some, but not all cells of contiguous filaments joined by cell fusions, no growth rhythms and no trichocytes occur. Cell length 9-22 Ám (M=14, SD=4), diameter 11-18 (M=13, SD=2). Subepithallial initials and epithallial cells not preserved.
Tetra/bisporangial conceptacles uniporate with cylindrical pores. Filaments around the conceptacle pore are arranged subparallel to the conceptacle roof. Conceptacle floor 0-4 cell layers below thallus surface (pl. 1, fig. 6). Conceptacle height 150-160 Ám, diameter 260-360 Ám, no columella found. Cell length in conceptacle roof 9-18 Ám (M=13, SD=3), diameter 7-13 Ám (M=9, SD=2). Shape of pore channel unknown. Sexual conceptacles and carposporangia unknown.
Remarks: This species encrusts other coralline algae. It was found in three samples. Measured samples: MOL292, MOL380
Spongites sp. 2 Description: Growth form fruticose, diameter of protuberances 2-3 mm, length up to 10 mm; thallus monomerous.
Core filaments non-coaxial, core portion usually 25-30 Ám thick, sometimes up to 80 Ám. Filaments only curve towards the dorsal thallus surface. Cell fusions present. Cell length 7-22 Ám (M=13, SD=6), diameter 6-9 Ám (M=7, SD=1).
Peripheral filaments: some parts of the thallus show growth rhythms with a thickness of 7-10 cell rows; cell length 6-11 Ám (M=10, SD=2), diameter 7-9 Ám (M=8, SD=1). Some cells of contiguous filaments are joined by cell fusions. Subepithallial initials and epithallial cells not preserved.
Tetra/bisporangial conceptacles uniporate, usually completely raised above thallus surface (i. e. conceptacle floor on the level of thallus surface; pl. 1, fig. 8). Conceptacle height 120-200 Ám, diameter 500-550 Ám. Pore length 150-180 Ám, diameter 110 Ám. Shape of pore channel most probably conical. Cell filaments around conceptacle pore are subparallel to the roof (pl. 1, fig. 8), measuring 11-18 Ám (M=14, SD=3) in length and 4-5 Ám (M=5, SD=1) in diameter. Filaments in distal portions of the roof are subperpendicular to the roof and show distinctively shorter cells: length 5-11 Ám (M=9, SD=2), diameter 4-9 Ám (M=5, SD=2). Sexual conceptacles and carposporangia unknown.
Remarks: Spongites sp. 2 was found in a single sample (MOL209).
Subfamily MELOBESIOIDEAE Bizzozero, 1885 Diagnosis: Tetra/bisporangial conceptacles multiporate, cell fusions present (Woelkerling, 1988).
Melobesioideae gen. et spec. indet.
Description: Growth form encrusting to warty and lumpy, thallus thickness in encrusting portions 0.3-0.4 mm. Protuberances are up to 3 mm in diameter and up to 5 mm long. Thallus organisation monomerous.
Core filaments non-coaxial, core portion usually 100-180 Ám thick; filaments only curve towards the dorsal surface. Cell fusions occur. Cell length 11-18 Ám (M=14, SD=3), diameter 11-13 Ám (M=13, SD=1).
Peripheral region in encrusting portion 220-300 Ám thick; growth rhythms occur, composed of up to 6 cells (pl. 2, fig. 3). Cell fusions abundant, trichocytes absent. Cell length 7-13 Ám (M=10, SD=2), diameter: 7-13 Ám (M=9, SD=2). Protuberances: Growth rhythms from 4 to 12 rows occur. Cell fusions abundant. Cell length 13-18 Ám (M=15, SD=1), diameter 7-11 Ám (M=9, SD=2). Epithallium and vegetative initials not preserved.
Tetra/bisporangial conceptacles usually raised one half above the thallus surface (pl. 2, fig. 3). Conceptacle height 170-200 Ám, diameter 350-600 Ám; roof thickness 55-90 Ám. Pore diameter 11-13 Ám. Length of cells in conceptacle roofs 7-9 Ám (M=8, SD=1), diameter 5-10 Ám (M=8, SD=2). Type of conceptacle roof formation unknown, sexual conceptacles and carposporangia unknown.
Remarks: In accordance with the traditional generic concepts of Wray (1977), this species would belong to Lithothamnion. However, this genus cannot be identified using present-day concepts owing to the unpreserved epithallial cells and subepithallial initials. Owing to the non-coaxial core filaments, it can be referred to either Lithothamnion or Phymatolithon (see also remarks of Phymatolithon).
The described species is most abundant in "Maerl"-type sediments (sensu Lemoine, 1910) forming isolated branches. Measured sample: MOL3a.
Genus Phymatolithon Foslie, 1898 Diagnosis: Plants lacking an arborescent growth form and haustoria. Thallus monomerous, core filaments non-coaxial, epithallial cells rounded or flattened, but not flared, subepithallial initials as short or shorter than underlying cells (Braga et al., 1993; Wilks & Woelkerling, 1994). Irvine & Chamberlain (1994) additionally define Phymatolithon by the "Phymatolithon-type" surface view of epithallial cells.
Remarks: Following Braga et al. (1993) this genus is indistinguishable from Leptophytum Adey (1966) in fossil material. This fact is reflected by the generic differentiation of Chamberlain & Keats (1994) who focus on growth form, surface view of epithallial cells, and whether the conceptacle initiation is "shallow" or "deep". However, the cited authors also mention that the differentiation between Lepthophytum and Phymatolithon is provisional. As Wilks & Woelkerling (1994) concluded that Leptophytum is not a distinct genus in the current state of research, it is not considered here. The occurrence of rounded epithallial cells and short subepithallial initials allows a distinct separation of Phymatolithon from other genera of this subfamily.
1957 Lithothamnium crispithallus Johnson: 231, pl. 42, figs 6-8.
1994 Lithothamnion sp.; Rasser: 198, pl. 3, figs 4, 5; pl. 2, fig. 6.
In prep. Phymatolithon sp.; Rasser & Piller
Description: Growth form encrusting to foliose (pl. 2, fig. 4) with a thallus thickness of usually 150 Ám. Sometimes warty growth forms occur with 1.3-1.4 mm long and 1.5-0.8 mm thick protuberances. Thallus monomerous.
Core filaments predominantly curve towards the dorsal, sometimes towards the ventral thallus surface. Core portion 70-150 Ám (mostly 100 Ám) thick, in layered to foliose portions usually at least 50% of the thallus thickness (pl. 2, fig. 6). Cell fusions occur. Cell length 14-29 Ám (M=19, SD=4), diameter 7-11 Ám (M=9, SD=1). The peripheral region in encrusting portions is restricted to the dorsal part of the thallus; it is usually 50 Ám thick but also up to 150 Ám. No growth rhythms occur. Cell length 7-16 Ám (M=11, SD=2), diameter 5-13 Ám (M=10, SD=2). Protuberances show 90-120 Ám thick growth rhythms. Cell fusions abundant, trichocytes absent, cell rows not regular. Cell length 7-18 Ám (M=11, SD=3), diameter 7-13 Ám (M=9, SD=2). Vegetative initials as short or shorter than underlying cells (pl. 2, fig. 8). Cell length 7-9 Ám, diameter 11-12 Ám. The epithallium is one cell-layer thick, the cells are rarely well preserved. The shape of epithallial cells is not clear, but they seem to be not flat (pl. 2, fig. 8). Cell length 8-9 Ám, diameter 11-12 Ám. Only few measurable epithallial cells and vegetative initials were found in the studied material. Therefore, M and SD were not calculated.
Tetra/bisporangial conceptacles are multiporate, without a rim, old conceptacles may be buried within the thallus. Conceptacles distinctively raised above the thallus surface with a floor usually ten cell layers below the thallus surface (less frequently only five) (pl. 2, fig. 5, 6). Height 100-160 Ám, diameter 210-460 Ám. Thickness of roof 45-70 Ám, conceptacle pore diameter up to 27 Ám. Length of cells in conceptacle roof 6-12 Ám (M=9, SD=3), diameter 5-8 Ám (M=7, SD=1). Conceptacle roof formed by filaments interspersed between sporangia (pl. 2, fig. 7). Sexual conceptacles and carposporangia unknown.
Remarks: As traditional concepts for fossil corallines do not take into account the occurrence of epithallial cells and subepithallial initials, this genus would, in the past, have been identified as Lithothamnion. This species is the same described by Rasser (1994) as Lithothamnion sp. Growth form, anatomy, and conceptacle size are close to those of Lithothamnion crispithallus Johnson (1957), which, following this work, should now belong to Phymatolithon. A new combination would, however, require a study of the original material and this has not been included in the present study. Phymatolithon sp. is the most abundant species in the studied material, forming coralline algal bindstones together with Neogoniolithon sp. Moreover, it is the dominant coral encruster. Measured samples: MOL12 and MOL291.
Family SPOROLITHACEAE Verheij, 1993
Diagnosis: Non-geniculate, almost entirely calcified thalli; both cell fusions and secondary pit connections occur; tetra/bisporangia formed between filaments, on one or more stalk cells, apical plug at tetra/bisporangial apex (Verheij, 1993).
Remarks: Verheij (1993) separated the family Sporolithaceae from the family Corallinaceae. Because of the preservation of calcified sori and paraphyses this family can easily be identified in fossil material.
Genus Sporolithon Heydrich, 1897
Diagnosis: Epithallial cells with flattened and flared cells and tetra/bisporangial conceptacles separated by interspersed calcified filaments (paraphyses) (Woelkerling, 1988); conceptacles arranged in sori (Verheij, 1993).
Sporolithon sp. 1
Description: Growth form encrusting to lumpy (pl. 3, fig. 1). Diameter of protuberances: 0.7-2 mm at the base and 0.8-3.4 mm at the top. Thickness of encrusting thalli up to 2 mm.
Core filaments strongly curve towards the dorsal, but never towards the ventral thallus surface (pl. 3, figs 2, 5). Thickness of core portion usually 30-50 Ám, sometimes up to 100 Ám. Irregular cell shapes, cell fusions occur. Cell length 20-36 Ám (M=29, SD=5), diameter 11-13 Ám (M=12, SD=1).
Peripheral portion 85 to 200 Ám thick, mostly 100 Ám. Cell shape rectangular; no growth rhythms and trichocytes occur; cell layers irregular; cell fusions occur. Cell length 25-30 Ám (M=28, SD=2), diameter 10-16 Ám (M=13, SD=2).
Some thalli show preserved epithallial cells which are characterised by brightish cell layers on the outermost thallus surfaces in thin section (pl. 3, fig. 2). SEM samples show that the epithallium is recrystallised and cells are replaced by large calcite crystals (pl. 3, figs 5, 6). Cell length approx. 7 Ám, diameter approx. 13 Ám. Owing to the poor state of preservation, the shape of epithallial cells cannot be identified.
Tetra/bisporangial conceptacles arranged in sori which rise approximately one half above the thallus surface. Sori consist of 12 to 45 tetra/bisporangia (pl. 3, fig. 1). Old sori are not flaked off, but buried in the thallus. Sori usually arise from a layer of elongated cells (pl. 3, fig. 3). Conceptacle shape elongated ellipsoidal. Tetra/bisporangia height 110-130 Ám, diameter 47-60 Ám. Two pores with a diameter of 24 Ám can be recognised in horizontal section, both of them surrounded by 7-8 rosette cells (pl. 3, fig. 4). 1-6 filaments (paraphyses) are interspersed between tetra/bisporangia (pl. 3, fig. 3). Number of cells in the paraphyses difficult to recognise. Most probably there are four cells with a length of 30-40 Ám. Sexual conceptacles and carposporangia unknown.
Remarks: This species cannot be compared with any previous species of Sporolithon. It is not abundant in the studied material and usually encrusts bioclasts. Measured sample: MOL377.
Sporolithon sp. 2
Description: Growth form encrusting (pl. 3, fig. 7). Several consecutive sori may occur within one thallus. Thallus thickness 0.8-1 mm.
Core portion 50-70 Ám thick. Cell dimensions not measurable owing to the poor preservation of core filaments.
Peripheral filaments are arranged in regular cell rows. Vertical filament walls are more distinct than the horizontal ones (pl. 3, fig. 8). Cell fusions abundant, trichocytes absent. Thickness of peripheral portion 350-500 Ám. Cell length 10-16 Ám (M=13, SD=2), diameter 7-9 Ám (M=8, SD=1).
Epithallium not preserved.
Tetra/bisporangia arranged in sori with up to 35 tetra/bisporangia each. Sori completely raised above the thallus surface. Sori do not arise from a layer of elongated cells. Old sori are not flaked off, but buried in the thallus. Conceptacle height 63-70 Ám, diameter 36-45 Ám. One to nine filaments interspersed between the tetra/bisporangia. Number of cells in the paraphyses unclear, they seem to vary between three and five. Sexual conceptacles and carposporangia unknown.
Remarks: This species cannot be compared with any previous species of Sporolithon. Only a single thallus of Sporolithon sp. 2 was found in the studied material (MOL220).