Dasycladalean algae distribution in ammonoid-bearing Middle Triassic platforms (Dolomites, Italy)

Abstract

This paper gives an account of distribution of Dasycladales in ammonoid-bearing Middle Triassic carbonate platforms of the Dolomites. A ca. 600-m-thick section was investigated within the Latemar platform interior and Dasycladales from correlated ammonoid-bearing samples of the Marmolada platform were studied for comparison. At Latemar, the dense sampling allowed, with some confidence, the identification of the first occurrences of Diplopora nodosa and Gyroporella ladinica, and the last occurrences of D. annulatissima and D. comelicana. Their stratigraphic range was found to be in agreement with literature. Other first or last occurrences could not be reconciled with known distributions, and were considered as environmentally or palaeogeographically controlled. All four algal events occur within a narrow interval of two Illyrian (Upper Anisian) ammonoid subzones (avisianum and crassus subzones). This study demonstrates the biostratigraphic potential of Dasycladales in platform settings, and highlights the necessity of detailed stratigraphic studies to determine their distribution.

Appendices

Appendix I

The aim of this part of the paper is only to describe dasycladalean taxa on which the correlation is based, instead of discussing taxonomical problems. The latter are only reported, in some particularly complex cases.

Systematic description

Phylum: Chlorophycophyta Papenfuss 1946

Class: Chlorophyceae Kützing 1843

Order: Dasycladales Pascheer 1931

Family: Diploporaceae (Pia 1920), Deloffre 1988

Tribe: Diploporeae Pia 1920 emend Güvenç 1979

Genus: Diplopora Schafhäutl 1863, emend Güvenç 1979

D. annulata (Schafhäutl 1853) Schafhäutl 1863

(Fig. 4a, b)

Selected synonymy

1853 Nullipora annulata n. sp.—Schafhäutl (1853), pl. VI, fig. 1a–f

1863 D. annulata n. gen. n. comb.—Schafhäutl (1863), pl. XLVe, fig. 6a, b

1899 D. annulata—Tornquist (1899), pl. XVIII, fig. 5a, b

1912 D. annulata—Pia (1912), pl. VII (VI), figs. 1, 2, 14, 15

1921 D. annulata—Bubnoff (1921), pl. X, fig. 13

1927 D. annulata—Ogilvie Gordon (1927), pl. IX, fig. 6

1950 D. annulata—Herak (1950), pl. I, figs. 2, 3

1957 D. annulata—Bystrický (1957), pl. VII, fig. 5

1957 D. annulata subsp. annulata n. subsp.—Herak (1957), p. 52 (no figure)

1963 D. annulata annulata—E. Flügel and Kirchmayer (1963), pl. X, fig. 2

1964 D. annulata var. annulata nom. nov.—Bystrický (1964), pl. XXIX, fig. 1–3

1965 D. annulata var. annulata, forma trichophora—Zanin Buri (1965), pl. 54, fig. 4

1970 D. annulata annulata—Patrulius (1970), pl. III, fig. 1

1972 D. annulata—Mišik (1972), pl. XXXVIII, fig. 2

1974 D. annulata—Zorn (1974), pl. I, fig. 1

1981 D. annulata—Gaetani et al. (1981), figs. 7, 15.8

1983 D. annulata—Fois and Jadoul (1983), pl. 1, fig. a pars

1986 D. annulata var. annulata—Bystrický (1986), pl. IV, fig. 1

1993 D. annulata—Senowbari-Daryan et al. (1993), pl. 55, fig. 7

1997 D. annulata—Pugliese (1997), pl. 1, figs. 6–9

2001 D. annulata—Bucur and Enos (2001), pl. 2, figs. 1–12, 14

Table 1 Measurements of D. annulata. D the diameter of the thallus, d the diameter of the central stem, H the thickness of the segments, h the distance of the laterals, p the diameter of the pores at the most wide place

Description

Thallus: Cylindrical, straight and thick well calcified wall. The external surface of the thallus is emphatic annulated. Central stem is cylindrical, relatively wide. The internal surface of the wall is smooth and straight. Whorled laterals, two whorls per segment. Transversal section is circular in shape.

Laterals: Double whorled, metaspondyl, trichophor type. From one base grow up two laterals in V shape. The distal part of the laterals is opened. The whorls insert perpendicularly on the central stem.

Occurrences: Austria: Tirol, Höllengebirge, Steyrtal, Croatia: Velebit Mt, Germany: Zugspitze, Poland: Upper Silesia, Tatra, Italy: Lombardia, Mendola, Marmolada, N Predazzo, Val di Fassa St. Cristina, Val Gardena (Trentino), Véneto, Friuli, Calabria, Switzerland: Ticino, Slovakia: Muranška Planina, Fatra, Male Karpaty, Serbia: Tara Mt, Romania: Apuseni Mt, Spain: NW Tarragona, Granada, Slovenia: W Kranjska Gora, Hungary: Aggtelek–Rudabánya Mts, Buda Hills, China: Guizhou

D. annulatissima Pia 1920

(Fig. 4c–d)

Selected synonymy

1919 D. annulata—Baretti (1919), fig. 1a

1919 Kantia monregalensis n. sp.—Baretti (1919), figs. 6a–c

1920 D. annulatissima n. sp.—Pia (1920), pl. IV, figs. 11–16

1927 D. annulatissima—Ogilvie Gordon (1927), pl. IX, figs. 1–3

1931 D. annulatissima—Pia (1931), pl. XXI, fig. 1

1950 D. annulatissima—Herak (1950), pl. II, fig. 4, pl. III, figs. 2, 3, pl. IV. fig. 1, 2

1957 D. annulatissima—Bystrický (1957), pl. VII, fig. 3

1959 D. annulatissima—Bystrický (1959), pl. XI, figs. 1–3, pl. XII, figs. 1–5

1961 D. annulatissima—Botteron (1961), pl. VII, fig. 1

1964 D. annulatissima—Bystrický (1964), pl. XXIV, figs. 4, 5, pl. XXV, fig. 4, pl. XXVI, figs. 3, 4, pl. XXVII, figs. 1–3, pl. XXVIII, figs. 1–4

1965 D. annulatissima—Herak (1965), pl. V, fig. 3

1966 D. annulatissima—Ott (1966), figs. 4, 5

1967 D. annulatissima—Rossi (1967), fig. 70

1972 D. annulatissima—Ott (1972), figs. 2, 1–10

1980 D. annulatissima—Dragastan (1980), pl. 5, fig. 3

1981 D. annulatissima—Gaetani et al. (1981), fig. 4

1983 D. annulatissima—Fois and Jadoul (1983), pl. 1, fig. b

1986 D. annulatissima—Senowbari-Daryan and Abate (1986), pl. 5, fig. 5

1987 D. annulatissima—Braga and Martín (1987), pl. I, fig. 1

1993 D. annulatissima—Senowbari-Daryan et al. (1993), pl. 55, figs. 1, 6, 8

1997 D. annulatissima—Pugliese (1997), pl. I, figs. 1–5

2001 D. annulata—Bucur and Enos (2001), pl. 3, figs. 1–13

Table 2 Measurements of D. annulatissima. Abbreviations see Table 1

Description

Thallus: Cylindrical, straight. Densely annulated. The annulation is deep and thick. The segments (rings) are thinner than the annulation. Central stem is cylindrical, relatively wider than the central stem of D. annulata. The internal surface of the wall is straight. Laterals are whorled, only one whorl per segment. Transversal section is circular in shape.

Laterals: Double whorled, metaspondyl, trichophor type. The laterals are thinner than in D. annulata. Two laterals in V shape grow from each base. The distal part of the laterals is opened. The whorls insert perpendicularly on the central stem.

Occurrences: Austria: Tirol, Kärtner, Hochschwab, Croatia: Lika, Poland: Upper Sylesia, Tatra, Italy: Piemonte, Marmolada (Trentino), Friuli, Sicilia, Switzerland: Schwyz, Tyrol, Slovakia: Stratenska hornatina, Slovensky kras, Malé Karpaty, Serbia: N Niš, Velebit Mt., Spain: Granada, Slovenia: W Jesenice, Hungary: Aggtelek–Rudabánya Mts, Montenegro: Sutomore, France: Savoie

D. nodosa Schafhäutl 1863, emend De Castro 1979

(Fig. 4p)

Selected synonymy

1863 D. nodosa n. sp.—Schafhäutl (1863), pl. LXV, figs. 19, 20

1971 Teutloporella nodosa—Zorn (1971), pl. 17, fig. 6

1979 D. nodosa—De Castro (1979), fig. 2A

1988 Teutloporella nodosa—Pfeiffer (1988), pl. 11, fig. 1

1995 Teutloporella nodosa—Pantić-Prodanović (1995), pl. I, fig. 8

Table 3 Measurements of D. nodosa. Abbreviations see at Table 1

Description

Thallus: Cylindrical, straight and relatively thick. The thallus forms a triangular segments. The diameter of the segments is half of the diameter of the annulation. Central stem is cylindrical, relatively thin. The internal surface of the central stem is smooth and straight. Whorled laterals, one segment per whorl. Transversal section is circular in shape.

Laterals: Whorled, euspondyl, trichophor type. The laterals are very thin. The distal part of the laterals is generally closed. The whorls insert obliquely on the central stem.

Occurrences: Croatia: Velebit Mt, Slovakia: E Trencín, Slovenský Kras, Malé Karpaty, Hungary: Aggtelek–Rudabánya Mts

D. comelicana Fois 1979

(Fig. 4g–h)

Selected synonymy

1979 D. comelicana n. sp.—Fois (1979), pl. 1, figs. 1–7

1983 D. comelicana—Fois and Jadoul (1983), pl. 1, fig. A

1986 D. comelicana—Bystrický (1986), pl. IV, figs. 2–4

Table 4 Measurements of D. comelicana. Abbreviations see at Table 1

Description

Thallus: Cylindrical, straight and relatively thick, well calcified. The external surface of the thallus is annulated. The annulation is deep. Central stem is cylindrical, extremely wide. The internal surface of the wall is smooth and straight. Whorled laterals. Transversal section of the thallus is circular in shape.

Laterals: Whorled, metaspondyl, vesiculifer type. Two or more laterals in V shape grow from each base. The proximal part of the laterals is long and thin. The distal part of the laterals flare vesical-like. The distal part of the laterals is generally closed (seldom opened). The whorls insert almost perpendicularly on the central stem.

Taxonomy: Güvenç (1979) suggested of his emendation of genus Diplopora to eliminate the forms with vesiculifer branches. He included these forms emended genus Kantia (Bucur and Enos 2001).

Occurrences: Italy: Veneto, Friuli, Slovakia: E Banská Bystrica

Family: Seletonellaceae (Korde 1950) Bassoulet et al. 1975

Tribe: Dasyporelleae (Pia 1920), Bassoulet et al. 1979

Sub-tribe: Macroporellinae (Pia 1920), Bassoulet et al. 1979

Genus: Macroporella Pia 1912, emend. Bassoulet et al. 1978

M. beneckei (Salomon 1895) Pia 1920

(Fig. 4i–k)

Selected synonymy

1895 D. Beneckei n. sp.—Salomon (1895), pl. I, figs. 21, 22a, b, 23–27

1920 M. beneckei n. comb.—Pia (1920), pl. I, figs. 24–26

1964 M. beneckei—Bystrický (1964), pl. VI, fig. 2

1965 M. beneckei—Herak (1965), pl. IX, fig. 3, pl. X, figs. 1–4

1967 M. beneckei—Pantić (1967), pl. IV, figs. 3, 4

1971 M. beneckei—Zorn (1971), pl. 17, fig. 8

1973 M. beneckei—Popa and Dragastan (1973), pl. XIX, fig. 76

1976 M. beneckei—Epting et al. (1976), fig. 8c

1988 M. beneckei—Pfeiffer (1988), pl. 11, fig. 3

1990 M. beneckei—Scheuber (1990), pl. 10, fig. 1

1994 M. beneckei—Flügel et al. (1994), pl. 1, fig. 1

Table 5 Measurements of M. beneckei. Abbreviations see at Table 1

Description

Thallus: Cylindrical, straight and thick well calcified wall. Central stem is cylindrical, relatively narrow. The internal surface of the wall is smooth and straight. Transversal section is circular in shape.

Laterals: Aspondyl, phloiophor type. The pores take place obliquely to the axial stem and widen to the outer side of the wall. The proximal part of the branch is thin, the distal is thick. The distal end of the laterals is opened. The laterals insert densely on the central stem.

The specimens are smaller than Diplopora specimens.

Occurrences: Austria: Kärnten, Croatia: N Knin, Italy: Marmolada (Trentino), Veneto, Switzerland: Ticino, Slovakia: Slovenský kras, Serbia: Tara Mt, Romania: Apuseni Mt, Spain: Granada, Slovenia: Bled, Hungary: Aggtelek–Rudabánya Mts

Tribe: Gyroporelleae Pal, 1976; emend.

Gyroporella ladinica Bystrický 1962

(Fig. 4m, n)

Selected synonymy

1962 G. ladinica—Bystrický (1962), pl. III, fig. 4

1964 G. ladinica—Bystrický (1964), pl. VII, fig. 1

Table 6 Measurements of G. ladinica. Abbreviations see at Table 1

Description

Thallus: Cylindrical, straight with a thin wall. The external wall of the thallus is smooth. The central stem is extremely wide.

Laterals: Single whorled, euspondyl, mainly vesiculifer type, but sometimes phloiophor. The distal part flares vesical-like. Laterals insert perpendicularly on the central stem. The whorls insert densely.

Grainer and Grgasović (2000) considered this species as a synonym of Poikiloporella duplicata, however, the thallus of this species is straight and bigger than in Poikiloporella duplicata, and misses the remnants of inner ring. Thus, we still consider G. ladinica a valid taxon.

Occurrences: Slovakia: Slovenský kras, Hungary: Bükk Mt

Family: Triploporaceae (Pia 1920), Berger and Kaever 1992

Tribe: Salpingoporelleae Bassoulet et al. 1979

Sub-tribe: Salpingoporellinae Bassoulet et al. 1979

Genus: Physoporella Steinmann 1903, emend. Pia 1912

Physoporella lotharingica (Benecke 1898) Pia 1931

(Fig. 4e–f)

Selected synonymy

1898 D. lotharingica n. sp.—Benecke (1898), fig. 1

1958 Physoporella lotharingica—Ellenberger (1958), pl. 7, figs. 17–19

1965 Physoporella lotharingica—Herak (1965), pl. XIV, figs. 4, 5

1997 Physoporella lotharingica—Pugliese (1997), pl. 1, figs. 10–13

Table 7 Measurements of Physoporella lotharingica. For abbreviations see Table 1

Description

Thallus: Cylindrical, straight with well calcified and relatively thin wall. The external wall of the thallus is deeply undulated. Calcification rings between the undulations are thinner than the undulation. Central stem is cylindrical and relatively thick. The internal surface of the central stem is smooth. Laterals are whorled, one segment per whorl. Transversal sections are circular in shape.

Laterals: Single whorled, euspondyl, pyriferous type. The base of the laterals is large in diameter, the distal part is closed. Laterals insert perpendicularly on the central stem.

The species seems identical to the Physoporella pauciforata var. undulata Pia 1935, but smaller (D: 0.7–0.9 mm in Physoporella lotharingica versus 2.0–3.6 mm in Physoporella pauciforata var. undulata, see Bystrický 1964).

Occurrences: Austria: Niederösterreich, Croatia: NW Knin, Lika, Italy: Basilicata, Spain: NW Tarragona, France: Moselle, Germany: Baden-Württemberg

Tribe: Dasyporelleae Pia 1920

Sub-tribe: Teutloporellinae Bassoulet et al. 1979

Genus: Euteutloporella De Castro 1993

Euteutloporella peniculiformis (Ott 1963) n. comb. Grgasović and Sokać 1999

(Fig. 4l)

Selected synonymy

1963 (nom. nud.) Teutloporella peniculiformis n. sp.—Ott (1963), figs. 14, 20–24

1966 (nom. nud.) Teutloporella peniculiformis—Ott (1966), fig. 3

1971 (nom. nud.) Teutloporella peniculiformis—Zorn (1971), pl. 4, fig. 4

1976 (nom. nud.) Teutloporella peniculiformis—Epting et al. (1976), fig. 6

1980 (nom. nud.) Teutloporella peniculiformis—Dragastan (1980), pl. VII, fig. 7

1989 (nom. nud.) Teutloporella peniculiformis—Buček (1989), pl. I, fig. 2.

1989 (nom. nud.) Teutloporella peniculiformis—Gaetani and Gorza (1989), Pl 10, fig. 5

1993 (nom. nud.) Teutloporella peniculiformis—Budai, Lelkes and Piros (1993), pl. VI, fig 1

1994 (nom. nud.) Teutloporella peniculiformis—Bucur et al. (1994), pl. 10, figs. 8, 9

1995 (nom. nud.) Teutloporella peniculiformis—Ott in Granier and Deloffre (1995), p. 57, no illustration

Table 8 Measurements of Euteutloporella peniculiformis. Abbreviations see at Table 1

Description

Thallus: The thallus has an appearance of a “fox tail”. Central stem is extremely thin. The relatively thick wall is pierced by numerous circular and weakly recognizable pores. Transversal sections of the thallus are circular or oval in shape. In transversal section the central stem is generally not visible, only the transversal sections of the laterals can be seen.

Laterals: Single whorled, euspondyl, trichophorous type. The base of the laterals is not wider than the distal part, the distal part is opened. The laterals straight obliquely to the central stem.

Taxonomy: Pia (1912) established the genus Teutloporella and included species with thin trichophorous laterals, mainly aspondyl, but sometimes euspondyl. Bassoulet et al. (1978) emended the genus to include only the aspondyl species, and the euspondyl ones were moved into the new genus Neoteutloporella. After the discovery of two-order laterals in Neoteutloporella socialis De Castro (1993) changed the diagnosis of the genus Neoteutloporella, and established the new genus Euteutloporella included the euspondyl species with trichophorous branches (Grgasović and Sokać 1999).

Occurrences: Hungary: Bakony, Aggtelek Mountains; Slovakia: Slovenský kras, Malé Karpaty, Italy: Veneto, Lombardia, Switzerland: Ticino, Romania: Apuseni Mt. Sasca Zone South Carpathians, Austria: Tyrol.

Family: Incertae sedis

Z. obscura Senowbari-Daryan and Di Stefano 2001

(Fig. 4p)

Selected synonymy

1972 “Problematikum 1”—Zorn (1972), pl. 3, fig. 1

2001 Z. obscura n. gen. n. sp.—Senowbari-Daryan and Di Stefano (2001), pl. IV, figs. 1–5

Description

Thallus: The skeleton of this alga consists of “horseshoe” or crescent-shaped mainly irregular walls surrounding a 0.3–0.5-mm-wide cavity. The cavity filled by calcite cement and/or bioclasts. Only identified in thin sections.

Laterals: Mainly pyrifer type. The distal ends are closed. The presence of whorls is not confirmed.

Taxonomy: The taxonomy of this species is problematical, because it only knows in transversal section and it is not enough for the reconstruction of the thallus.

Occurrences: Italy: Cozzo Paparina (Sicily)