STYLATRACTIDAE Schröder, 1909

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 : 457-459

Family STYLATRACTIDAE Schröder, 1909 n. stat.

sensu Matsuzaki et al. (2015)

Stylatractida [sic] Schröder, 1909: 37 (= Stylatractidae ) [as a subfamily].

Sphaerostylida Haeckel, 1882: 451 [nomen dubium, as a tribe];1887: 122, 133 [as a subfamily]. — Schröder 1909: 7 [as a subfamily].

Amphistylida Haeckel, 1882: 452 [nomen dubium, as a tribe]; 1887: 142 [as a subfamily].

Cromyostylida Haeckel, 1882: 453 [nomen dubium, as a tribe]; 1887: 146 [as a subfamily].

Caryostylida Haeckel, 1882: 454 [nomen dubium, as a tribe]; 1887: 148 [as a subfamily].

Ellipsida Haeckel, 1887: 289 [nomen dubium, as a family]. — Rüst 1892: 150 [as a family]. — Carter 1893: 227 [as a family]. — Wisniowski 1889: 684 [as a family]. — Anderson 1983: 23 [as a family].

Sphaerostylinae – Clark & Campbell 1942: 24 [nomen dubium]; 1945: 11. — Campbell & Clark 1944a: 10; 1944b: 4. — Chediya 1959: 80.

Amphistylinae – Clark & Campbell 1945: 13 [nomen dubium]. — Campbell 1954: D54. — Chediya 1959: 82.

Lithapinae Deflandre, 1953: 418 [as a new Nassellaria subfamily].

Cromyostylinae – Campbell 1954: D54 [nomen dubium].

Ellipsidiicae – Campbell 1954: D68 [nomen dubium, as a superfamily].

Ellipsidiidae – Campbell 1954: D68 [nomen dubium]. — Kozur & Mostler 1979: 38-39 ( sensu emend. ).

Caryostilinae – Chediya 1959: 82 [nomen dubium].

Stylatractidae – Nishimura 1990: 156 [as a new Nassellaria family].

Amphisphaeridae Suzuki in Matsuzaki, Suzuki & Nishi, 2015: 10 [nomen dubium].

TYPE GENUS. — Stylatractus Haeckel, 1887: 328 [type species by subsequent designation ( Campbell 1954: D73): Stylatractus neptunus Haeckel 1887: 328 ] = junior subjective synonym of Druppatractylis Haeckel, 1887: 325 [type species by subsequent designation ( Campbell 1954: D71): Druppatractus ostracion Haeckel, 1887: 326 ].

INCLUDED GENERA. — Druppatractylis Haeckel, 1887: 325 (= Stylatractylis n. syn.; Lithatractara , Lithatractus synonymized by Kozur & Mostler 1979: 40; Stylatractara , Stylatractus synonymized by Petrushevskaya 1975:570). — Ellipsostylus Haeckel, 1887: 299 (= Ellipsostyletta with the same type species; Ellipsostylissa n. syn., Sphaerostylomma n. syn.). — Lithapium Haeckel, 1887: 303 (= Xiphatractara , Xiphatractus synonymized by Petrushevskaya 1975: 570; Xiphatractium n. syn.). — Lithomespilus Haeckel, 1882: 450 . — Stylatractona Haeckel, 1887: 330 (= Amphisphaerissa synonymized byPetrushevskaya 1975: 570). — Stylosphaerantha Haeckel, 1887: 133 (= Praestylosphaera synonymized by O’Dogherty et al. 2009a: 283;? Xiphosphaerantha n. syn.). — Xiphatractylis Haeckel, 1887: 332 (= Cromydruppocarpus n. syn., Heliosestarium n. syn.,? Xiphosphaeromma n. syn.). — Xiphostylantha Haeckel, 1887: 127 (= Druppatractus , Druppatractara , Sphaerostylantha , synonymized by Petrushevskaya 1975: 570). — Xiphostylissa Haeckel, 1887: 129 (= Xiphostyletta n. syn.).

INVALID NAMES . — Ellipsis, Spongostylidium.

NOMINA DUBIA. — Amphisphaera, Amphisphaerantha, Amphisphaerella, Amphisphaeromma , Amphistylus, Axellipsis , Caryostylus, Cenellipsis, Cenellipsium, Cenellipsula, Cromyostaurolonche , Cromyostylus, Druppatractium, Echinocapsa , Ellipsidium, Ellipsoxiphetta, Sphaerostyletta, Sphaerostylissa , Spongolonchis, Spongostylium, Stylatractium, Stylocromyum, Xiphatractona, Xiphosphaerissa.

JUNIOR HOMONYM. — Spongolonche Haeckel, 1882: 455 (= Spongolonchis ) nec Haeckel, 1882: 461; Sphaerostylus Haeckel, 1882 nec Chaudoir, 1854.

DIAGNOSIS. —The shell consists of one to three concentric shells with bi-polar spines (rarely one). The innermost shell, if present, contains a spherical microsphere with many radial beams. The second inner shell is also a spherical macrosphere and this shell is connected to the outermost shell by many radial beams. The outermost shell is a cortical shell, occasionally found with by-spines or a fragile coverage. Most radial beams are disconnected between the concentric shells. A dark gray endoplasm occupies the cortical shell in Stylatractona .

REMARKS

Since the Cenozoic Genera Working Group (CGW) decided to exclude any genera based on unfigured type species, the genus Amphisphaera is regarded as a “ nomen dubium.” Its type species, Amphisphaera neptunus Haeckel, 1887 , has been interpreted as a probable junior synonym of Stylatractus neptunus ( Petrushevskaya 1975; Hollis 1997). However, CGW postponed this decision. Therefore, the name Amphisphaeridae by Matsuzaki et al. (2015) should also be regarded as “ nomen dubium ”. The subfamily/family rank commonly used for this group has been “Lithapiinae”, originally pertained to the Nassellaria by Deflandre (1953) and Nishimura (1990) respectively; however, many authors have overlooked the name Stylatractidae proposed earlier by Schröder (1909). Stylatractidae is easily distinguishable from both Stylosphaeridae and Entapiidae due to the presence of an innermost pyriform shell. The genera Druppatractylis , Lithapium and Stylatractona are maintained as valid for future discussions although their basic differences only depend upon the position of the spines. Internal skeletal structure was illustrated for Stylatractona in fossils ( Nakaseko & Nishimura 1982: pl. 17, fig. 4; Sugiyama et al. 1992: pl. 3, fig. 8) and a living form ( Suzuki & Not 2015: fig. 8.10.13).

VALIDITY OF GENERA

Druppatractylis

The combination of Lithatractus and Lithatractara , and that of Stylatractus and Stylatractara have respectively the same type species. As the definitions written for Lithatractus and Stylatractus are the same even in Campbell (1954: D72 for Lithatractus and D73 for Stylatractus ), both these genera are mostly conspecific. Stylatractylis is marked by a thorny or papillate surface ( Campbell 1954: D73) but the type-illustration does not match with this description. Based on the principle of the name-bearing specimen, the type species for these three genera has a common structure as written in the Atlas .

Ellipsostylus

Ellipsostyletta has the same type species as Ellipsostylus . Both Ellipsostylus and Ellipsostylissa have a single elliptical shell and two opposite dissimilar polar spines, but the former has a regular network whereas the latter has an irregular network ( Campbell 1954: D68-69 for Ellipsostylus and D69 for Ellipsostylissa ). The difference in the network is insufficient as a genus criterion. Sphaerostylomma is marked by two concentric lattice shells, irregular pores with dissimilar sizes and presence of by-spines or thorns on the cortical shell ( Campbell 1954: D54). Any specimens identical to the type species of these three genera are very rare so it is not possible to examine their descriptions in detail and these genera are tentatively synonymized here. All these genera are simultaneously established by Haeckel (1887: 299 for Ellipsostylus , 299 for Ellipsostyletta , 301 for Ellipsostylissa , and 140 for Sphaerostylomma ). As a real specimen identifiable of Ellipsostylus psittacus , the type species of Ellipsostylus , has been found in the topotypic material of the H.M.S. Challenger Station 265, this genus is selected as a valid genus among the other ones.

Lithapium

Xiphatractus has the same type species as Xiphatractara . Specimens with no internal structure whose characteristics fit with the type-illustration in Haeckel (1887: pl. 14, fig. 9) are always associate with specimens having three concentric shells in the topotypic material from the H.M.S. Challenger Station 266. Based on this observation, the definition of Lithapium has changed in the Atlas . As Lithapium , the lectotype of Xiphatractium also has three concentric shells ( Ogane et al. 2009b: pl. 12, figs 3a-d). Xiphatractus has three concentric shells based on its type-illustration ( Haeckel 1887: pl. 17, fig. 11). Distinguishing characters are an elliptical or pear-shaped cortical shell with a single spine on one pole for Lithapium ( Campbell 1954: D69); a cortical shell with a smooth surface and a regular network, and two opposite dissimilar polar spines for Xiphatractus ( Campbell 1954: D73); and a cortical shell with a thorny or papillate surface and an irregular network, and also two dissimilar spines for Xiphatractium ( Campbell 1954: D73). As indicated by the type-illustration of Lithapium ( Haeckel 1887: pl. 14, fig. 9), Lithapium pyriforme has two opposite dissimilar polar spines and this character can be confirmed with topotypic specimens from the H.M.S. Challenger samples (the supporting image for Lithapium ). The lectotype of Xiphatractium does not match with the description by Campbell (1954: D73). Rather, pore arrangement and size patterns are the same in the type species of both Xiphatractus and Xiphatractium . Although the exact internal structure is not well known for Xiphatractus and Xiphatractium , it is unnecessary to keep these three genera valid. All genera were simultaneously described in Haeckel (1887: 303 for Lithapium , 332 for Xiphatractus , 331 for Xiphatractara , and 334 for Xiphatractium ). Lithapium is validated among them because many representative specimens are found in the topotypic material.

Stylatractona

The concept of this genus corresponds to the current usage of Amphisphaera . The difference between Stylatractona and Amphisphaerissa at “genus” level is the presence of an irregular network in the former ( Campbell 1954: D73) or in the presence of irregular pores with dissimilar sizes in the latter ( Campbell 1954: D54). This difference cannot be recognized from type-illustrations ( Haeckel 1887: pl. 17, fig. 2 for Stylatractona and pl. 17, fig. 5 for Amphisphaerissa ). No other differences are observed in the type species of both these genera. These two genera were simultaneously established in Haeckel (1887: 330 for Stylatractona and 144 for Amphisphaerissa ). Stylatractona is validated because of a better illustrated type specimen in Haeckel (1887: pl. 17, fig. 2). The differences between Lithapium and Stylatractona need a more precise study.

Stylosphaerantha

Xiphosphaerantha is questionably synonymized with Stylosphaerantha herein, in consideration of the same number of shells and the bladed polar spines. This synonymy needs to evaluate by trace of evolutionary continuity between the type species of Stylosphaerantha and that of Xiphosphaerantha .

Xiphatractylis

Differing from the other genera of the Stylatractidae , Xiphatractylis has several radial spines which are directly connected by radial beams and these radial spines tend to appear in the equatorial zone of the shell. Xiphosphaera was defined by a double medullary shell, two opposite dissimilar polar spines, a regular network, and a spiny or thorny surface ( Campbell 1954: D73), but this definition does not match with the lectotype which has only two lattice shells ( Ogane et al. 2009b: pl. 3, figs 6a, 6b). Any well-preserved specimens identifiable as Heliosestarium cretaceum, the type species of Cromydruppocarpus , are not so far formally illustrated, so the total number of shells cannot be confirmed. However, the taxa belonging to the Stylatractidae are rarely associated with robust radial spines in the equatorial zone of the shell. Xiphosphaeromma is defined by the presence of irregular pores with dissimilar sizes, a spiny or thorny surface, two similar polar spines and a single latticed shell ( Campbell 1954: D54). The specimen most similar to the type image for Xiphosphaeromma was found from an upper Eocene Barbados sample (supporting image for Xiphosphaeromma ). If this specimen is the true Xiphosphaeromma vestum , this genus has three concentric shells and robust radial spines which are not connected by radial beams. This internal structure is similar to that of some Actinommidae . Until the internal structures could be well described, Xiphatractylis , Praestylosphaera, Heliosestarium and Xiphosphaerantha are synonymized herein. The oldest available names are Xiphatractylis and Xiphosphaeromma which were simultaneously published by Haeckel (1887: 322 for Xiphatractylis and 126 for Xiphosphaeromma ). As the real type specimen of Xiphatractylis is in the Ehrenberg collection, Xiphatractylis is selected as a valid name.

Xiphostylantha

Druppatractus hippocampus is the type species of three genera Druppatractus , Druppatractara and Sphaerostylantha . Xiphostylantha was defined by a single lattice shell, two dissimilar polar spines, regular pores with similar sizes, and no by-spines or thorns on the surface ( Campbell 1954: D54). The shorter polar spine of Xiphostylus phasianus , the type species of Xiphostylantha , is so characteristic of the Stylatractidae that this species is a synonym of “ Stylosphaera coronata ” (the supporting image for Xiphostylantha ). The lectotype of the latter species ( Ogane et al. 2009b: pl. 12, figs 1a-d) has two shells so Xiphostylantha should be regarded as a genus with two shells. Druppatractus is defined by an elliptical shell, a simple medullary shell and two dissimilar polar spines ( Campbell 1954: D71). The sphericity of the outer shell in both Xiphostylantha and Druppatractus is a little bit different but it is explained by a difference at the species level. These two genera were simultaneously published by Haeckel (1887: 127 for Xiphostylantha and 324 for Druppatractus ). The first genus in Haeckel (1887) is validated.

Xiphostylissa

Following Campbell (1954: D54), Xiphostylissa and Xiphostyletta have a common structure with a single lattice shell and dissimilar polar spines. The difference is the absence of by-spines and thorns in Xiphostylissa and the presence of byspines and thorns in Xiphostyletta . These characters, however, are helpless to precisely determine the real specimen referable to their type species, Xiphostylus trogon for Xiphostylissa ( Haeckel 1887: pl. 14, fig. 12) and Xiphostylus picus for Xiphostyletta ( Haeckel 1887: pl. 14, fig.13). Based on the type-illustrations, Xiphostylissa lacks a prominent polar spine whereas Xiphostyletta has a prominent polar spine. The difference in its length can be explained by an intraspecies variation.

STRATIGRAPHIC OCCURRENCE. — Late Campanian-Holocene.