342


Journal of Paleontology 92(3):336–372


the late Silurian–Mississippian, rare to very rare in the Pennsylvanian–Permian.


Remarks.—Eovolutinidae (= Rauserinidae) emend. herein encompasses the eovolutinins (with two concentric chambers), rauserinins (with clusters of unilocular chambers), and vicine- sphaerins (strictly unilocular) (e.g., the genera Eovolutina Antropov, 1950; Rauserina Antropov, 1950; Vicinesphaera Antropov, 1950; Archaesphaera Suleimanov, 1945 [partim]; Serginella Pronina, 1963; Paralagena Sabirov, 1986; and ?Tscherdyncevella Antropov, 1950). They are the most primi- tive parathuramminids due to the presence, among them, of Vicinesphaera Antropov, 1950 as early as in the Cambrian of Kazakhstan and the Early Ordovician of Mexico (Vachard et al., 2017). The family Eovolutinidae is often confused with the Archaesphaeridae Poyarkov, 1979 auctorum, which could therefore have priority; nevertheless, it is more probable that Archaesphaera Suleimanov, 1945 is a transverse section of Eotuberitina Miklukho-Maklay, 1958, and therefore is a tuberitinoid rather than a parathuramminoid. However, true Eotuberitina seem to appear in Upper Devonian deposits, and an


“Archaesphaera”, such as that of Flügel and Hötzl (1971, fig. 1.1, 1.2), belongs to another taxon, which are either oblique sections of Eovolutina cutting only the external chamber, or oblique sections of Ivanovella, which do not pass by the external spines.


Family Ivanovellidae Chuvashov and Yuferev in Zadorozhnyi and Yuferev, 1984


Diagnosis.—Small- to moderate-sized unilocular tests with spherical to polygonal central chamber. Radiate to irregularly arranged protuberances of the wall; either unperforated or when possessing a central neck, the latter does not communicate with the external environment. Inconspicuous apertures. Wall dark- microgranular.


Occurrence.—Early Ordovician to Late Devonian in Laurussia, Siberia and eastern Paleotethys (Tian Shan and South China).


Remarks.—The Ivanovellidae are partly synonymous with Psammosphaeridae sensu Miklukho-Maklay, 1965 (non Haeckel, 1894, nec Cushman, 1927). They are composed of Ivanovella Pronina, 1969; Lechangsphaera Lin, 1984; Neoiva- novella Chuvashov and Yuferev in Dubatolov, 1981; Neoarchaesphaera Miklukho-Maklay, 1963 (non 1958); Ele- nella Pronina, 1969; ?Ratella Kotlyar, 1982; and ?Turcmeniella Miklukho-Maklay, 1965. The mazzuelloid microproblematica are probably recrystallized (phosphatized) ivanovellids. Maz- zuelloids were interpreted as microfossils with an original phosphatized wall (Kozur, 1984), but a secondary phosphati- zation is more probable (Hüsken and Eiserhardt, 1997; Kremer, 2005; and general discussion of the problems of phosphatization in Porter, 2004 and Zhuralev and Wood, 2008). Hüsken and Eiserhardt (1997) advocated for a phosphatization of the organic


wall of acritarchs, but it seems that their illustrations (pl. 1, fig. 15, pl. 2, figs. 1–4) most probably correspond to secondarily phosphatized ivanovellids (perhaps Neoarchaesphaera spp.). The material illustrated by Kremer (2005) seems also to belong


to Neoarchaesphaera. Moreover, because the mazzuelloids are known from Late Ordovician to Early Devonian, they have a stratigraphic distribution similar to that of the ivanovellids. Genus Ivanovella Pronina, 1969


Type species.—Ivanovella isensis Pronina, 1969.


Other species.—See Chuvashov and Yuferev in Dubatolov (1981) and Zadorozhnyi and Yuferev in Dubatolov (1981).


Diagnosis.—Test unilocular, with spherical central chamber and radiate necks, prominent at the periphery and not commu- nicating with the external environment. Inconspicuous aper- tures. Wall dark-microgranular.


Occurrence.—Ludlovian–Pridolian of the central and northern Urals. Late Emsian of Gornyi Altai. Middle Devonian–Frasnian of the Tomsk area (SW Siberia). Late Emsian–Frasnian of southwestern Siberia (the Famennian age indicated byVdovenko et al., 1993, p. 29, is possibly due to a lapsus calami).Discovered in the Givetian ofMount Polinik (Carnic Alps, Austria).


Ivanovella sp. 1 Figure 10.13


Diagnosis.—The test is small; the chamber is subhexagonal; the necks are short and subtriangular.


Occurrence.—Only one sample in the Givetian of Mount Polinik (Carnic Alps, Austria).


Description.—Outer diameter=0.08mm; inner diameter= 0.04mm; test wall thickness=0.01mm.


Materials.—Only one specimen (sample POL11a-9).


Ivanovella sp. 2 Fig. 10.14


Diagnosis.—The test consists of an irregularly polygonal chamber; the necks are long, thin and triangular.


Occurrence.—Only one sample in the Givetian Feldkogel Limestone of Mount Polinik (Carnic Alps, Austria).


Description.—Outer diameter=0.13mm; inner diameter= 0.08mm; test wall thickness=0.005mm.


Materials.—Only one specimen (sample POL11a-10b).


Ivanovella sp. 3 Figure 10.15


Diagnosis.—The test consists of a polygonal chamber with a thick wall; the necks are long, triangular to thin and occasionally curved.


Occurrence.—Rare in the Givetian Feldkogel Limestone of Mount Polinik (Carnic Alps, Austria).


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