Back
Malvinia
From Williams et al., 2017:
[Malvinia, Houben et al., 2011, p. 177.
Type species: Malvinia escutiana, Houben et al., 2011 (pl.1, figs.1–3)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Huben et al., 2011]:
Diagnosis:
Non-cavate spherical peridinioid dinocyst of intermediate size. Tabulation reflected by faint sutural ridges. Malvinia has a theropylic archeopyle, representing a split along the margins of the anterior intercalary- and apical series. All plates remain attached to the cyst. The cingulum consists of three plates and a small transitional plate. The anterior part of the cyst always appears distorted as a consequence of the archeopyle type.
Description:
Proximate subsphaerical cyst of intermediate size. The cyst wall consists of one relatively thin layer. Tabulation is marked by faint parasutural ridges and reflects a protoperidinioid pattern (pr, 4 , 3a, 7 , 1t, 3c, 5″′, 2″″). The archeopyle is interpreted as a theropylic type consisting of a straight split along the anterior margins of the anterior intercalary plates (1a, 2a and 3a), which remain attached to the cyst along their posterior margins. The split extends between the anterior intercalary plates (1a with 2a and 2a with 3a) and between the anterior intercalary- and apical plates (1a with 2 and 3 , 2a with 3 and 3a with 3 and 4 ) as shown in Fig. 3. This type of archeopyle typically causes the anterior part of the cyst to collapse, which is therefore found strongly distorted.
Affinities:
Echinidium Zonneveld 1997 is a protoperidinioid genus with a theropylic archeopyle, it differs from Malvinia in having brown pigmentation and spinose ornamentation. Dubridinium Reid 1977 has a theropylic archeopyle but differs from Malvinia in being cavate and its tabulation reflects the cingulum only. Subtilisphaera Jain and Millepied 1973 has a transverse archeopyle and incomplete parasutures along individual anterior intercalary plates. Algidasphaeridium Matsuoka and Bujak 1988 differs from Malvinia in having a chasmic archeopyle. Malvinia differs from Islandinium Head et al. 2001, which has a saphopylic archeopyle with loss of the apical series (i.e. 2 , 3 and 4 ). Cryodinium Esper and Zonneveld 2002 is a round brown cyst with a fully reflected tabulation on the epi- and hypocyst, it primarily differs from Malvinia since in its archeopyle type, which is a combination intercalary type involving plates 1a and 2a. Brigantedinium Reid 1977, Lejeunecysta Artzner and Dörhöfer, 1978 and Selenopemphix Benedek 1972 are fossil genera of round, brown cysts related to extant Protoperidinium species that are non tabular and have a simple archeopyle formed by the detachment of the anterior intercalary plate 2a. Phthanoperidinium Drugg and Loeblich 1967 is a fossil peridinioid dinoflagellate genus that includes subsphaerical forms with sutural ornamentation and a closely appressed endo- and periphragm. Typically an apical projection is present. Edwards and Bebout (1981) and Islam (1982) emended the genus to include different archeopyle types; I (2a), IP (2a and 4 ), 3I (1a–3a), 3IP (1a, 2a, 3a and 4 ) and 3I3P (1a–3a, 3″–5 ). The distinct therophylic archeopyle type is characteristic for Malvinia. Phthanoperidinium has four roughly equally sized cingular plates and is therefore not considered protoperidinioid. An apical projection has not been observed in Malvinia.
[Malvinia, Houben et al., 2011, p. 177.
Type species: Malvinia escutiana, Houben et al., 2011 (pl.1, figs.1–3)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Huben et al., 2011]:
Diagnosis:
Non-cavate spherical peridinioid dinocyst of intermediate size. Tabulation reflected by faint sutural ridges. Malvinia has a theropylic archeopyle, representing a split along the margins of the anterior intercalary- and apical series. All plates remain attached to the cyst. The cingulum consists of three plates and a small transitional plate. The anterior part of the cyst always appears distorted as a consequence of the archeopyle type.
Description:
Proximate subsphaerical cyst of intermediate size. The cyst wall consists of one relatively thin layer. Tabulation is marked by faint parasutural ridges and reflects a protoperidinioid pattern (pr, 4 , 3a, 7 , 1t, 3c, 5″′, 2″″). The archeopyle is interpreted as a theropylic type consisting of a straight split along the anterior margins of the anterior intercalary plates (1a, 2a and 3a), which remain attached to the cyst along their posterior margins. The split extends between the anterior intercalary plates (1a with 2a and 2a with 3a) and between the anterior intercalary- and apical plates (1a with 2 and 3 , 2a with 3 and 3a with 3 and 4 ) as shown in Fig. 3. This type of archeopyle typically causes the anterior part of the cyst to collapse, which is therefore found strongly distorted.
Affinities:
Echinidium Zonneveld 1997 is a protoperidinioid genus with a theropylic archeopyle, it differs from Malvinia in having brown pigmentation and spinose ornamentation. Dubridinium Reid 1977 has a theropylic archeopyle but differs from Malvinia in being cavate and its tabulation reflects the cingulum only. Subtilisphaera Jain and Millepied 1973 has a transverse archeopyle and incomplete parasutures along individual anterior intercalary plates. Algidasphaeridium Matsuoka and Bujak 1988 differs from Malvinia in having a chasmic archeopyle. Malvinia differs from Islandinium Head et al. 2001, which has a saphopylic archeopyle with loss of the apical series (i.e. 2 , 3 and 4 ). Cryodinium Esper and Zonneveld 2002 is a round brown cyst with a fully reflected tabulation on the epi- and hypocyst, it primarily differs from Malvinia since in its archeopyle type, which is a combination intercalary type involving plates 1a and 2a. Brigantedinium Reid 1977, Lejeunecysta Artzner and Dörhöfer, 1978 and Selenopemphix Benedek 1972 are fossil genera of round, brown cysts related to extant Protoperidinium species that are non tabular and have a simple archeopyle formed by the detachment of the anterior intercalary plate 2a. Phthanoperidinium Drugg and Loeblich 1967 is a fossil peridinioid dinoflagellate genus that includes subsphaerical forms with sutural ornamentation and a closely appressed endo- and periphragm. Typically an apical projection is present. Edwards and Bebout (1981) and Islam (1982) emended the genus to include different archeopyle types; I (2a), IP (2a and 4 ), 3I (1a–3a), 3IP (1a, 2a, 3a and 4 ) and 3I3P (1a–3a, 3″–5 ). The distinct therophylic archeopyle type is characteristic for Malvinia. Phthanoperidinium has four roughly equally sized cingular plates and is therefore not considered protoperidinioid. An apical projection has not been observed in Malvinia.