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Sphaeripilosa
From Fensome et al., 2019:
Sphaeripilosa Soliman and Lucas-Clarke 2018, p.32. Type: Soliman and Lucas-Clarke 2018, pl.2, figs.1–3, as Sphaeripilosa wernerpilleri.
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Original description Soliman and Lucas-Clark, 2018:
Derivation of name. Sphaera (L. sphere) and pilosa (L. hairy), referring to the overall morphology of the cysts.
Type species. Sphaeripilosa wernerpilleri n. sp.
Diagnosis. Proximochorate to chorate, acavate, spherical to subspherical organic-walled, peridinioid dinoflagellate cysts covered with hair-like or similar, solid processes. Hexa-bipesoidal, episomal tabulation(?). Archeopyle mesoepicystal (3A3I). Cysts transparent to light brown in color.
Description. Small, organic-walled, peridinioid dinoflagellate cysts: acavate, spherical to sub-spherical (lacking horns), transparent to light-brown in color, proximochorate to chorate. Wall consists of an autophragm covered with hair-like or similar, solid processes. Cingulum and sulcus usually not indicated. Tabulation indicated by archeopyle only, or faintly by alignment of processes, or by bare linear areas free of processes along the cingulum and/or plate margins or by clusters of processes. Tabulation of the epicyst interpreted as standard peridiniacean (?pr, 4′, 3a, 7″) inferred from the details of the archeopyle. Tabulation of the hypocyst usually not indicated, but antapical plates may be suggested by clusters of processes (see Plate III, 11). Archeopyle large, mesoepicystal (3A3I), formed by loss of 3 apical plates (2′–4′) and 3 intercalary plates (1a–3a); operculum simple. Shape of the dorsal edge of the archeopyle suture may suggest a hexa plate 2a. The ventral edge of the archeopyle may be characterized by the presence of the anterior tip of apical plate 1′ and/or preapical plates or an indecipherable protrusion (“tab”) into the archeopyle. Archeopyle may be rounded so that tabulation is obscured.
Remarks. Assignment to Ovoidinioideae is based on evidence of the hexa-bipesoidal, episomal tabulation seen in some specimens (second anterior intercalary plate 2a appears to be 6-sided, based on the angles of its outline in the archeopyle see Plate III, 10). Also, the archeopyle is centered about the apical region and the cyst wall is organic (not calcareous) (see Fensome et al., 1993, p. 135).
Comparison. Sphaeripilosa gen. nov. is similar to Algidasphaeridium Matsuoka and Bujak, 1988 and Echinidinium Zonneveld, 1997, but both of these have chasmic archeopyles and are classified as Gymnodiniales and Incertae Sedis respectively. Sphaeripilosa is quite similar to Islandinium Head et al., 2001, which, however, is partly apiculocavate (implying two walls) and possibly epicavate (Head et al., 2001, plate 2, e; Islandinium minimum) and has an apical (3A) archeopyle that occupies less space on the cyst than the mesoepicystal (3A3I) archeopyle of Sphaeripilosa. Islandinium also has either a pointed termination of 1″ or a preserved canal plate in the ventral/apical position, similar to the tab of Sphaeripilosa, but less variable. Also, the holotype and other species of Islandinium are brown and regarded as “round brown” dinoflagellates which are classified as protoperidiniaceans (Head et al., 2001). Sphaeripilosa has been mistaken for Batiacasphaera Drugg 1970, which is described by Stover (1977) as having a gonyaulacoid, apical archeopyle involving four apical plates (tA). Wood et al. (2016) transferred species of Batiacasphaera with processes to Sentusidinium, which would thus now accommodate species similar to Sphaeripilosa but with gonyaulacoid apical archeopyles. Sphaeripilosa has a shape and mesoepicystal archeopyle similar to that of Arcticacysta Sangiorgi et al., 2009 but differs in having hair-like processes, a rounded archeopyle lacking accessory archeopyle sutures, and a variable but not pointed first apical. Other species, such as Calciodinellum kergulensis Streng et al., 2004, with mesoepicystal archeopyles have calcareous cyst walls, and have been assigned to the subfamily Calciodinelloideae (Fensome et al., 1993, Sangiorgi et al., 2009).
Sphaeripilosa Soliman and Lucas-Clarke 2018, p.32. Type: Soliman and Lucas-Clarke 2018, pl.2, figs.1–3, as Sphaeripilosa wernerpilleri.
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Original description Soliman and Lucas-Clark, 2018:
Derivation of name. Sphaera (L. sphere) and pilosa (L. hairy), referring to the overall morphology of the cysts.
Type species. Sphaeripilosa wernerpilleri n. sp.
Diagnosis. Proximochorate to chorate, acavate, spherical to subspherical organic-walled, peridinioid dinoflagellate cysts covered with hair-like or similar, solid processes. Hexa-bipesoidal, episomal tabulation(?). Archeopyle mesoepicystal (3A3I). Cysts transparent to light brown in color.
Description. Small, organic-walled, peridinioid dinoflagellate cysts: acavate, spherical to sub-spherical (lacking horns), transparent to light-brown in color, proximochorate to chorate. Wall consists of an autophragm covered with hair-like or similar, solid processes. Cingulum and sulcus usually not indicated. Tabulation indicated by archeopyle only, or faintly by alignment of processes, or by bare linear areas free of processes along the cingulum and/or plate margins or by clusters of processes. Tabulation of the epicyst interpreted as standard peridiniacean (?pr, 4′, 3a, 7″) inferred from the details of the archeopyle. Tabulation of the hypocyst usually not indicated, but antapical plates may be suggested by clusters of processes (see Plate III, 11). Archeopyle large, mesoepicystal (3A3I), formed by loss of 3 apical plates (2′–4′) and 3 intercalary plates (1a–3a); operculum simple. Shape of the dorsal edge of the archeopyle suture may suggest a hexa plate 2a. The ventral edge of the archeopyle may be characterized by the presence of the anterior tip of apical plate 1′ and/or preapical plates or an indecipherable protrusion (“tab”) into the archeopyle. Archeopyle may be rounded so that tabulation is obscured.
Remarks. Assignment to Ovoidinioideae is based on evidence of the hexa-bipesoidal, episomal tabulation seen in some specimens (second anterior intercalary plate 2a appears to be 6-sided, based on the angles of its outline in the archeopyle see Plate III, 10). Also, the archeopyle is centered about the apical region and the cyst wall is organic (not calcareous) (see Fensome et al., 1993, p. 135).
Comparison. Sphaeripilosa gen. nov. is similar to Algidasphaeridium Matsuoka and Bujak, 1988 and Echinidinium Zonneveld, 1997, but both of these have chasmic archeopyles and are classified as Gymnodiniales and Incertae Sedis respectively. Sphaeripilosa is quite similar to Islandinium Head et al., 2001, which, however, is partly apiculocavate (implying two walls) and possibly epicavate (Head et al., 2001, plate 2, e; Islandinium minimum) and has an apical (3A) archeopyle that occupies less space on the cyst than the mesoepicystal (3A3I) archeopyle of Sphaeripilosa. Islandinium also has either a pointed termination of 1″ or a preserved canal plate in the ventral/apical position, similar to the tab of Sphaeripilosa, but less variable. Also, the holotype and other species of Islandinium are brown and regarded as “round brown” dinoflagellates which are classified as protoperidiniaceans (Head et al., 2001). Sphaeripilosa has been mistaken for Batiacasphaera Drugg 1970, which is described by Stover (1977) as having a gonyaulacoid, apical archeopyle involving four apical plates (tA). Wood et al. (2016) transferred species of Batiacasphaera with processes to Sentusidinium, which would thus now accommodate species similar to Sphaeripilosa but with gonyaulacoid apical archeopyles. Sphaeripilosa has a shape and mesoepicystal archeopyle similar to that of Arcticacysta Sangiorgi et al., 2009 but differs in having hair-like processes, a rounded archeopyle lacking accessory archeopyle sutures, and a variable but not pointed first apical. Other species, such as Calciodinellum kergulensis Streng et al., 2004, with mesoepicystal archeopyles have calcareous cyst walls, and have been assigned to the subfamily Calciodinelloideae (Fensome et al., 1993, Sangiorgi et al., 2009).