TREMATODISCOIDEA Haeckel, 1862

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 : 433

Superfamily TREMATODISCOIDEA Haeckel, 1862

sensu Suzuki emend. herein

Trematodiscida Haeckel, 1862: 240, 485, 491 [as a tribe]; 1882: 459 [as a tribe]; 1887: 484, 491 [as a subfamily].

Trematodiscea – Zittel 1876-1880: 124 [rank unknown].

Trematodiscacea – Kozur & Mostler 1978: 125-126 [as a superfamily]; 1990: 217-218 [as a superfamily].

Stylodictyoidea – Suzuki in Matsuzaki et al. 2015: 25.

DIAGNOSIS. — Flat or convex lens shape with circular outline. Central structure consisting of many discontinuous rings connected by short radial beams or a microsphere with four decussated primary radial spines.

REMARKS

This superfamily includes only the family Trematodiscidae . Homeomorphy between Spongodiscoidea and Trematodiscoidea was first detected by a molecular phylogenetic study ( Ishitani et al. 2012). The group of Schizodiscus, Spongobrachiopyle , Flustrella and Stylodictya was analyzed by molecular studies and further subdivided into two subgroups, namely a subgroup of Schizodiscus and Spongobrachiopyle (originally Spongopyle ) as Clade L2, and a subgroup of Flustrella and Stylodictya as Clade J ( Sandin et al. 2021). The former group morphologically corresponds to the Spongopylidae and the latter to the Trematodiscidae . The general morphology of Spongopylidae closely resembles that of Spongodiscidae (Spongodiscoidea) . It is estimated that identifying the classical Spongodiscidae family, used to include the Spongodiscoidea and Trematodiscoidea is difficult. However, this is largely due to an insufficient observation of many taxonomical markers. In particular, the difference in the disk’s lateral profiles is almost completely ignored. This complicates the taxonomic process. The structural difference between the “empty” space and “thin” structural parts must be carefully recognized upon dark to bright appearance of disc parts under a light microscope. An “empty” space can be bright irrespective of disk thickness. Meanwhile, a “thin” place may be bright based on its relationship to the disk thickness. It is sometimes presumptively concluded, to a fault, that differences in brightness may be caused by supplemental gowns on both faces of the disk. If this is observed, shallow depth focused photos are essential. Many previous papers repeatedly noticed the different lateral profiles of the classical Spongodiscidae ( Müller 1859b: pl. 1, figs 8, 9; Haeckel 1862: pl. 27, figs 3, 5; pl. 28, figs 6, 9; 1887: pl. 42, figs 5, 6, 9, 10; Hertwig 1879: pl. 6, 7a, 7b, 8a; JØrgensen 1905: pl. 10, figs 39a, 40b, 41c; Riedel 1953: pl. 84, fig. 6; Kozlova 1960; Krasheninnikov 1960: 3, figs 5-7; Moksyakova 1961: pl. 1, fig. 11; 1972: pls 1-9; Kozlova & Gorbovetz 1966: pl. 14, figs 1-2; Petrushevskaya 1967: pl. 19, fig. 2; pl. 20, figs 2, 4; pl. 21, figs 3, 6; pl. 22, fig. 7; pl. 25, figs 3, 5; 1975: pl. 34, figs 1, 2; pl. 36, figs 3, 5; pl. 38, figs 1, 3, 7; pl. 39, figs 2; pl. 40, fig. 4, Barwicz-Piskorz 1978: pl. 5, figs 1-3; Zaynutdinov 1978: pl. 7, figs 1-3; pl. 12, fig. 7; Petrushevskaya & Kozlova 1979: figs 431, 432, 434, 438, 441; Nakaseko & Nishimura 1982: pl. 29, fig. 1c; pl. 31, figs 2b, 3a; pl. 32, fig. 3; pl. 34, fig. 2a; pl. 37, fig. 1b; pl. 40, fig. 6b; pl. 41, fig. 2a; pl. 42, figs 1, 4; pl. 43, figs 1b, 2a; Poluzzi 1982: pl. 20, fig. 17; O’Connor 1997b: text-fig. 2; pl. 4, figs 4, 6; Ogane & Suzuki 2006 : pl. 1, figs 6, 9; pl. 2, fig. 2; Onodera et al. 2011: pl. 6, fig. 6). The difference of lateral profile in classic Spongodiscidae is directly related to the fundamental rule of skeletal growth patterns and construction scheme of a biological design. Regardless of the repeated rediscovery of this profile difference, systematic examination regarding these differences have been under-appreciated and the majority of studies identify a spongy disk without radial spines as Spongodiscus , a spongy disk without radial spines as Spongotrochus , a spongy disk with a pylome as Spongopyle , a concentric disk without radial spines as Porodiscus , and/or a concentric disk with radial spines as Stylodictya . Everyone empirically knows that this simple scheme does not work for any real specimens. This is easily recognizable if we look at names such as Spongodiscus spp. , Spongodiscidae gen. et sp. indet. and other ambiguous indications for classic Spongodiscidae . Nevertheless, the validity of described genera such as Schizodiscus, Spongobrachiopyle, Spongospira and Staurospira was rejected without any further careful anatomical considerations. It is noteworthy that some studies still strongly adhere to this flawed principle, despite the clear rejection of this treatment by the molecular phylogeny ( Ishitani et al. 2012). To understand these groups, shallow focus photos like pl. 13, fig. 3a of Suzuki et al. (2009d) are essential. Otherwise, progress is stifled.