PLECTOPYRAMIDIDAE Haecker, 1908

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 : 475-477

Family PLECTOPYRAMIDIDAE Haecker, 1908

Plectopyramididae Haecker, 1908: 157 . — Petrushevskaya & Kozlova 1972: 550. — Dumitrica 1979: 34. — Hollis 1997: 71.

Acropyramida Haeckel, 1882: 428 [nomen dubium, below tribe].

Archiphormida Haeckel, 1882: 428 [nomen dubium, as a tribe]; 1887: 1133, 1158, 1159 [as a subfamily].

Haliphormida Haeckel, 1882: 428 [junior homonym, below tribe].

Archiphormididae – Campbell 1954: D118 [nomen dubium]. — Takahashi 1991: 136.

Archiphormidinae – Campbell 1954: D118 [nomen dubium].

Archiphorminae – Clark & Campbell 1942: 64 [nomen dubium]; 1945: 34. — Campbell &Clark 1944a: 39; 1944b: 21. — Chediya 1959: 192.

Plectopyramidinae – Petrushevskaya 1971a: 225-226 ( sensu emend. ); 1971b: 986 ( sensu emend. ). — Takahashi 1991: 113.

Acropyramididae – Petrushevskaya 1981: 155-157 [nomen dubium]; 1986: 135. — Kozlova 1999: 124-125. — De Wever et al. 2001: 245-246. — Afanasieva et al. 2005: S295. — Afanasieva & Amon 2006: 143.

Cornutellidae Takemura, 1986: 68. — Nishimura 1990: 150-151, 153 ( sensu emend. ).

TYPE GENUS. — Plectopyramis Haeckel, 1882: 432 [type species by subsequent designation ( Campbell 1954: D128): Plectopyramis magnifica Haeckel, 1887: 1257 ] = junior subjective synonym of Cinclopyramis Haeckel, 1879: 705 [type species by monotypy: Cinclopyramis murrayana Haeckel, 1879: 705 ].

INCLUDED GENERA. — Cinclopyramis Haeckel, 1879: 705 (= Cephalopyramis n. syn., Plectopyramis n. syn., Sestropyramis n. syn., Spongopyramis n. syn.: Enneapleuris synonymized by Suzuki et al. 2009d: 262, Peripyramis synonymized by Suzuki et al. 2009d: 262, Sethopyramis synonymized by Suzuki et al. 2009d: 262). — Cladarachnium Haeckel, 1882: 430 . — Cornutella Ehrenberg, 1839: 128 (= Cornutissa with the same type species; Orthocornutanna n. syn.). — Haliphormartidium Campbell, 1951: 528 . — Litharachnium Haeckel, 1861b: 835 (= Litharachnidium with the same type species). — Polypleuris Haeckel, 1887: 1260 .

INVALID NAMES . — Ceratarachnium, Craspedilium, Sethodrepanum.

NOMINA DUBIA. — Acropyramis , Actinopyramis , Archiphormis , Bathropyramis , Cladopyramis , Cornutanna , Cornutosa, Heterocornutanna , Hexapleuris , Litharachnoma .

JUNIOR HOMONYMS. — Cornutellium Haeckel, 1887 (= Cornutella ), nec Haeckel, 1882; Haliphormis Haeckel, 1887 (= Haliphormartidium ) nec Ehrenberg, 1847.

DIAGNOSIS. — Plectopyramididae consist of high-angled conical or very flat umbrella-like shaped shells. They appear as two segmented Nassellaria from an anatomical point of view but seem to be single segmented. The cephalic initial spicular system is highly degraded in some members. The proximal part above the cephalis is poreless and covered with a thick wall. The thoracic part is constructed of a gridwork pore frame. Pores are usually distributed in a longitudinal direction. If existent, four collar pores are visible in Cinclopyramis and Cornutella , and three collar pores are observed in Polypleuris . Endoplasm is small yet very long and thee cephalic part includes a proximal top. No pseudopodia or algal symbionts were observed.

STRATIGRAPHIC OCCURRENCE. — Late Anisian-Living.

REMARKS

The protoplasm and living specimen images were illustrated for Cornutella ( Gowing 1993: fig. 6j; Suzuki & Not 2015: fig. 8.10.19), Litharachnium ( Zhang et al. 2018: 15, fig. 4.16, p. 21, fig. 8.9) and Polypleuris ( Suzuki & Not 2015: fig. 8.10.21). Environmental molecular data indicate a deep-water normal environment for the Plectopyramididae ( Sandin et al. 2019). The cephalic structure was observed and documented for Cinclopyramis ( Nishimura & Yamauchi 1984: pl. 25, fig. 9b; Takemura & Yamauchi 1984: pl. 1, fig. 5; Nishimura 1990: figs 32.4b, 32.6b, 32.10b; Sugiyama 1998: pl. 5, fig. 10b), Cornutella ( Nishimura & Yamauchi 1984: pl. 25, figs 5b, 7b; Takemura & Yamauchi 1984: pl. 1, figs 1-3; Nishimura 1990: fig. 32.9b; Sugiyama 1998: pl. 6, fig. 1b), Litharachnium ( Cachon & Cachon 1972a: fig. 9) and Polypleuris ( Nishimura 1990: figs 32.1b, 32.2b, 23.3c, 32.5c). The development stage of the cephalic initial spicular system is variable among the genera. MB, V- and double L-rods occasionally develop in Cornutella with infra-species variations ( Nishimura 1990: fig. 32.8b). It was presumed that the initial spicule was embedded in the cephalic wall but this prediction was discarded after careful examination of thin-walled Cornutella specimens by Sugiyama (1998: 237). Cinclopyramis always has a cephalic initial spicular system consisting of MB, A-, D-, V-, double L-rods, and a cephalic basal ring. Litharachnium has both D- and double L-rods but the MB seems to be degraded. The apertural view of Polypleuris shows the presence of MB, D-, V-, double l-, and double L-rods, as well as a basal ring-like structure.

VALIDITY OF GENERA

Cinclopyramis

As pointed in Suzuki et al. (2009d: 262), Cinclopyramis was published by Haeckel (1879: 705) but not Haeckel (1887). Cinclopyramis includes the current usage of Acropyramis and Bathropyramis whose type species have not been illustrated. The genera synonymized in our paper are classified into two different subsuperfamilies in the sense of Campbell (1954): one is “Archipiliilae” defined by no joints and strictures on shells ( Campbell 1954: D117) and the other one is “Sethopiliilae” whose shells are divided by transverse strictures into cephalis and thorax ( Campbell 1954: D122). These differences do exactly reflect the absence of a cephalic cavity for the former group ( Haeckel 1879: pl. 16, fig. 8 for Cinclopyramis ; Haeckel 1887: pl. 54, fig. 5 for Peripyramis ). The latter is relevant to the presence of a cephalic cavity ( Haeckel 1887: pl. 54, fig. 6 for Enneapleuris , pl. 54, fig. 2 for Sethopyramis and pl. 56, fig. 10 for Spongopyramis ) and of a ball-like cephalis ( Bury 1862: pl. 11, fig. 1 for Plectopyramis ; Haeckel 1887: pl. 56, fig. 7 for Cephalopyramis ; Ogane et al. 2009b: the lectotype shown in pl. 21, figs 6a-6d for Sestropyramis ). However, there are no specimens without cephalic cavities in these groups so the differences at the Campbell’s (1954) subsuperfamily level are wrong. This can be also concluded at the family and subfamily levels in the sense of Campbell (1954). The former two genera belong to the “Archiphormidinae” of the “ Archiphormididae ” ( Campbell 1954: D118) whereas the remaining six genera to the “Sethophormidinae” of the “ Sethophormididae ” ( Campbell 1954: D124). These families are defined by exactly the same phrases: “radial apophyses 4 to 9 or more” for both “Archiphormidiae” and “ Sethophormididae ”. These subfamilies are also expressed with the exactly same phrases: “basal shell mouth open” for both “Archiphormidinae” and “Sethophormidinae”. Thus, even under the concept of Campbell (1954), all these genera belong to the same family and “subfamily.” The distinguishing characters are a double meshwork in Cinclopyramis ( Campbell 1954: D118), an outer mantle in Peripyramis ( Campbell 1954: D119) and meshes closed by a spongy framework in Spongopyramis ( Campbell 1954: D128). These characters are relied to ontogenetic growth differences formed by the secondary growth mode of Ogane et al. (2009c) in some limited species. In ignoring these secondary growth parts, Cinclopyramis and Peripyramis include a morphotype with a pyramidal shell with straight ribs and simple fenestration, and nine radial ribs in the thorax. This was cited from the definition for Sethopyramis in Campbell (1954: D127). This obviously indicates a synonymy relationship among Cinclopyramis , Sethopyramis and Peripyramis . Enneaphormis is marked by meshes fenestrated by secondary lattices and eight to nine radial beams ( Campbell 1954: D127), but this can be synonymized with these three genera as discusses here. The type-illustration for Spongopyramis shows irregular framed pores, differing from any other genera listed here. Spongopyramis -like morphotypes seemed to be limited in range but this difference is not sufficient to be regarded as to constitute an independent genus from the others. Plectopyramis , Cephalopyramis and Sestropyramis are characterized by the presence of a ball-like cephalis but this character has not been used for genus differentiation. Instead, Cephalospyris is distinguished by nine radial ribs in the thorax ( Campbell 1954: D127) and Sestropyramis by six radial ribs in the thorax ( Campbell 1954: D127) as a subgenus of Plectopyramis ( Campbell 1954: D128). The number of “radial ribs in the thorax” is not significant among their type-illustrations as to be relevant for genus differences. In conclusion, these three genera are synonyms. The specimens with ball-like cephalis are generally found in the Eocene but it is unclear whether this character is of genus or species level. The oldest available name is Cinclopyramis .

Cornutella

Cornutissa has the same type species as Cornutella . Semiobjective morphological studies of Cornutella by Reynolds (1978) are references to evaluate the validity of genera for the Cornutella group. Cornutella in the sense of Reynolds (1978) is subdivided into two genera ( Cornutanna and Cornutella ) by occurrence of an apical horn in Campbell (1954: D121) but this character is obviously an infraspecific variation. Orthocornutanna is marked by a straight shell axis ( Campbell 1954: D121) but a curved specimen was found in the Messinian (by upper Miocene-upper upper Miocene; Cortese & BjØrklund 1999: figs 21.G, 21.I). These curved specimens including the topotype of Cornutella clathrata ( Suzuki et al. 2009c: pl. 16, figs 4a, 4b) are not significant to separate Orthocornutanna from Cornutella . The oldest available name is Cornutella .