SPHAEROZOIDAE Müller, 1859

Suzuki, Noritoshi, Caulet, Jean-Pierre & Dumitrica, Paulian, 2021, A new integrated morpho- and molecular systematic classification of Cenozoic radiolarians (Class Polycystinea) - suprageneric taxonomy and logical nomenclatorial acts, Geodiversitas 43 (15), pp. 405-573 : 530-532

Family SPHAEROZOIDAE Müller, 1859

Sphaerozoen Müller, 1859a: 17 [as a family].

Sphaerozoida – Haeckel 1862: 240, 521-522 [as a family]; 1882: 472 [as a family];1884: 28 [as a family]; 1887: 10, 38-39 [as a family]. — Mivart 1878: 179 [as a subsection]. — Brandt 1885: 212-214 [rank unknown]. — Bütschli 1889: 1947 [as a family]. — nec Rüst 1892: 132 [as a family]. — Ludwig 1908: 17 [rank unknown]. — Anderson 1983: 23.

Collozoida Haeckel, 1862: 240, 522 [as a tribe]; 1882: 472 [as a family]; 1884: 28 [as a family]; 1887: 10, 23-24 [as a family]. — Bütschli 1889: 1947 [as a family]. — Ludwig 1908: 17 [rank unknown]. — Anderson 1983: 23.

Rhaphidozoida Haeckel, 1862: 240, 522, 525 [as a tribe].

Sphaerozoidae – Claus 1876: 160. — Delage & Hérouard 1896: 202 [as a suborder]. — Lankester et al. 1909: 145. — Enriques 1919: 57; 1932: 983. — Hollande & Enjumet 1953: 108. — Campbell 1954: D46. — Chediya 1959: 67. — Strelkov & Reshetnyak 1971: 317. — Nakaseko & Sugano 1976: 118. — Dumitrica 1979: 26. — Anderson 1983: 71. — Takahashi 1991: 61. — van de Paverd 1995: 34. — Tan 1998: 90 Tan & Chen 1999: 117. — De Wever et al. 2001: 173. — Afanasieva et al. 2005: S306.

Sphaerozoiden – Hertwig 1879: 158-160 [as a family]. — Brandt 1882: 388-400; 1905: 314-316 [as a family].

Collozoidae – Delage & Hérouard 1896: 201 [as a suborder]. — Campbell 1954: D44. — Chediya 1959: 66. — Tan 1998: 87. — Tan & Chen 1999: 114. — Anderson et al. 2002: 1001.

TYPE GENUS. — Sphaerozoum Meyen, 1834: 163 [type species by monotypy: Sphaerozoum fuscum Meyen, 1834: 164 ].

INCLUDED GENERA. — Belonozoum Haeckel, 1887: 39 . — Collozoum Haeckel, 1862: 522 (= Collodinium with the same type

species; Coinozoum n. syn., Collodastrum synonymized by Haeckel 1887: 28, Xantozoum n. syn.). — Rhaphidozoum Haeckel, 1862: 529 (= Rhaphidonactis with the same type species; Rhaphidoceras synonymized by Popofsky 1920: 587; Rhaphidonura synonymized by Popofsky 1920: 567). — Sphaerozoum Meyen, 1834: 163 (= Sphaerozonoceras with the same type species; Actinozoum n. syn.; Sphaerozonura synonymized by Popofsky 1920: 568).

NOMINA DUBIA. — Jozoum, Sphaerozonactis .

DIAGNOSIS. — Sphaerozoidae consist of colonial Collodaria with isolated siliceous spicules. Each cell is surrounded by isolated siliceous spicules located inside a gelatinous matter. Algal symbionts generally surround each collodarian cell or are found scattered throughout the gelatinous matter. The shape of the colony changes within the same species. Each cell possesses many nuclei that are observable in the endoplasm.

STRATIGRAPHIC OCCURRENCE. — Living.

REMARKS

Very small differences between isolated siliceous spicules, analyzed in molecular phylogeny by Biard et al. (2015), may reflect significant molecular differences.For fully grown spicules it may be possible to specify the small clades of Biard et al. (2015) but younger spicules share common shapes. Thus, it is impossible to determine the relevant clades of Biard et al. (2015). A colony in which isolated siliceous spicules are evenly distributed may be found in plankton samples. This is probably an intermediate condition between colonial and solitary forms and a part of the life stage (see remarks in Thalassicolloidea ). Isolated siliceous spicules are occasionally encountered in rocks and sediments, but it is impossible to classify them as Thalassosphaeridae or Sphaerozoidae . If new research might prove that Thalassosphaeridae correspond to a different life stage of the Sphaerozoidae , the isolated siliceous spicules would be identified as fragments of Sphaerozoidae . Collozoum and Sphaerozoum are easily collected in shallow, warm waters; as such many living and fixed cells images were provided. “Living” images were illustrated for Collozoum ( Anderson 1980: fig. 9; 1983: figs 1.5.A-1.5.B, 2.17; Swanberg & Harbison 1980: figs 2, 6; Swanberg & Anderson 1981: figs 1A-1D; De Wever et al. 1994: figs 6.a, 6.b; Matsuoka 2007: fig. 4.g; Suzuki & Aita 2011: figs 5F, 5G; Probert et al. 2014: S1, PAC 17, S2, SES 46, VEPO-14; Suzuki & Not 2015: figs 8.13.3- 8.13.5), Rhaphidozoum ( De Wever et al. 1994: fig. 14; Probert et al. 2014: S1, PAC 8; Suzuki & Not 2015: fig. 8.13.6), and Sphaerozoum ( Anderson 1976b: pl. 1, figs 1, 2; 1983: figs 1.5.C-1.5.D; Suzuki & Aita 2011: fig. 5C, 5D; Probert et al. 2014: S1, SES 47; Yuasa & Takahashi 2014: figs 1A, 1B; Suzuki & Not 2015: fig. 8.13.7). Algal symbionts and nuclei were also illustrated with epi-fluorescent observation with DAPI dyeing for Sphaerozoum ( Suzuki et al. 2009b: figs 1N, 1O; Zhang et al. 2018: 9, figs 4-6), Rhaphidozoum ( Zhang et al. 2018: 11, figs 26, 27). Collozoum was used for studies on the ultrafine cellular structure ( Anderson1976c; 1983;Swanberg & Anderson 1981: Villar et al. 2018), food preference ( Anderson 1980) and transcriptome analysis ( Balzano et al. 2015). The ultrafine cellular structure ( Anderson 1976b; 1981) and food preference of Sphaerozoum ( Anderson 1980) has been well documented. One of the most important discover on Sphaerozoum has been the identification of the silicalemma, that is the cytokalymma in which the silica precipitate (Anderson 1981: fig. 13-13). The presence of crystals in a cell was already reported in Collozoum and Sphaerozoum by Haeckel (1862) (see Strelkov & Reshetnyak 1971: 305-306 for history of the study). The mineralogy in question is strontium sulfate and was found in reproductive swarmers of Sphaerozoum ( Hollande 1974; Hollande & Martoja 1974) and ultrafine cellular structure ( Yuasa & Takahashi 2014). From an historical point of view, the study of algal symbionts in Collosphaeridae are important because the Zooxanthella nutricula give the root of the common name “zooxanthella”. It was formally described for the first time in Collozoum inerme byBrandt (1882). Algal symbionts of Collozoum, Rhaphidozoum and Sphaerozoum were identified as Brandtodinium nutricula by Probert et al. (2014). The variety of symbiosis is largely documented in Collozoum . Hyperiid amphipod genus Hyperietta juveniles remain inside the gelatinous matter of Collozoum longiforme as an obligate parasite and they swim elsewhere after consuming the algal symbionts ( Swanberg & Harbison 1980). A similar photography was captured in Biard et al. (2016: extended data fig. 3.d). A single Hyperietta stephenseni (Lestrigonidae) individual can hold a fan-shaped flat colony of Collozoum pelagicum because this amphipod uses the colony to paraglide water flows (Nakamura et al. 2019: fig.S2.d). Other parasites were reported from Collozoum as Bod insidiosus ( Hollande & Enjumet 1953: 173-174), Merodinium brandti ( Chatton 1923) and M. belari ( Hollande & Enjumet 1953: 159-165; 1955: figs 3, 4), and also from Sphaerozoum as Merodinium dolosum and M. asturum ( Chatton 1923) . However, regardless of the efforts ( Dolven et al. 2007; Bråte et al. 2012), little progress has been made regarding the molecular study of these parasites relative to the morpho-species.

VALIDITY OF GENERA

Collozoum

As no papers explained the definition of Coinozoum, we present a translated summary of this genus from Enriques (1919): “ Colony in vegetative mode is cylindrical with a length <10 mm; width <1-2 mm; vacuoles usually present, irregularly distributed; the colonies may appear segmented as if they were miniature C. inerme ; plasmodia somewhat large as in C. radiosum ; oil droplets colorless to very light yellow (only visible after squishing the colony). ” As this genus is defined by characteristics of the colony, not radiolarian cells, and Coinozoum was established as a subgenus of Collozoum , we simply synonymize this subgenus with Collozoum .

Xantozoum has not been explained in any papers. Enriques (1919: 21) erected this genus to apply only to Collozoum fulvum . The translated summary of Brandt’s (1885: 223) description of C. fulvum is as follows: “ Colony spherical or ellipsoidal with one large or many small vacuoles. Individuals spherical, slightly flattened with a circular outline. Central capsule delicate.Two layers of nuclei. Numerous yellow inclusions in the protoplasm. ” This genus was also established based on colony shape. Under the current taxonomic scheme, colony shape is useless for define species, genera, or other any taxonomic levels in Collodaria .

Collodastrum was defined as:“ form of the central capsules irregular and indefinite, variable, commonly polyhedral or polygonal, or amoeboid, often with irregular, finger-like processes ” ( Haeckel 1887: 27). The type species is Sphaerozoum pelagicum , but this species lacks isolated siliceous spicules, so it belongs to Collozoum . The oldest available name is Collozoum .

Rhaphidozoum

Rhaphidonactis has the same type species as Rhaphidozoum , which is characterized by two to four shanks on radiate spicules, while Rhaphidoceras has complex spicules with rays at both ends, and in Rhaphidonura , “ complex spicules include both radiate type with rays from central point and branched type with rays at both ends ” ( Campbell 1954: D46). The current concept of Rhaphidozoum is defined by: “ spicules partly simple and partly branched or radiate ” ( Campbell 1954: D46). This definition covers the characteristics of Rhaphidoceras and Rhaphidonura . Rhaphidozoum is the oldest available name among them. However, molecular phylogenetic analyses revealed very high diversity in the current Rhaphidozoum at the genus and family levels ( Biard et al. 2015).

Sphaerozoum

Sphaerozoum was studied mainly by Brandt (1885) and Strelkov & Reshetnyak (1971). Brandt (1885: 229) described this genus as: “ Skeletons always present and consist of numerous needle-like spines that are not connected and are distributed tangentially in individuals ” (translated from German by J.-P. Caulet). Strelkov & Reshetnyak (1971) described it as: “ This genus includes, as the only skeletal elements, double (pairedtriradiate) spines as the main axis, bearing at the ends two, three, four, or more lateral branches. These branches can be simple and are most frequently smooth ( Sphaerozoum punctatum ) or ramified and covered with spinules ( S. verticillatum )” (translated from Russian by J.-P. Caulet). Enriques (1919: 61, 63) defines Actinozoum as: “ the main characteristic of this group is the greatest preponderance of complicate spicules ” (translated from Italian by J.-P. Caulet) and Haeckel (1887: 45) defines Sphaerozonura as: “ Spicules all geminate-radiate, but with different, variable numbers of shanks on each end of the middle rod . ” These characteristics are covered by Brandt’s (1885) definition, rather than that ofStrelkov & Reshetnyak (1971). Sphaerozoum is the oldest available name among them. As with Rhaphidozoum , molecular phylogenetic analyses revealed very high diversity in the current Sphaerozoum at the genus and family levels ( Biard et al. 2015).