ASTRACTURIDAE Haeckel, 1882

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 : 419-420

Family ASTRACTURIDAE Haeckel, 1882

Astracturida Haeckel, 1882: 458 [as a tribe]; 1887: 458, 469 [as a subfamily].

Astracturinae – Campbell 1954: D82. — Chediya 1959: 130. — Petrushevskaya 1979: 113 ( sensu emend. ). — Amon 2000: 49.

Astracturidae – Kozur & Mostler 1972: 46-48.

TYPE GENUS. — Astractura Haeckel, 1882: 458 [type species by subsequent designation ( Campbell 1954: D82): Astractura ordinata Haeckel, 1887: 476 ] = junior subjective synonym of Astromma Ehrenberg, 1846: 385 [type species by subsequent monotypy: Astromma aristotelis Ehrenberg, 1847: 55 ].

INCLUDED GENERA. — Astromma Ehrenberg, 1846: 385 (= Astractinium with the same type species; Astractura n. syn., Astracturium n. syn., Astrococcura n. syn., Staurococcura n. syn.). — Amphactura Haeckel 1882: 468 (=? Dicoccura n. syn.,? Diplactinium n. syn.). — Hymeniastrum Ehrenberg, 1846: 385 (= Hymenastrella with the same type species; Hymenactura n. syn., Hymenacturium n. syn., Trigonactinium n. syn.; Hymenactinium , Pentactura , Trigonacturium synonymized by Kozur & Mostler 1972: 46).

INVALID NAMES . — Amphiactura, Astrococcus .

NOMEN DUBIUM. — Diplacturium .

DIAGNOSIS. — Roughly flat shell with a large convex lens-shaped latticed shell. A three-dimensional grid-like architecture formed by the arms is observed; frequently evolving from two to four arms, rarely more. Radial beams arise from the outer medullary shell and radiate towards both sides of the equatorial plane. These beams are connected to the large latticed shell. A bladed, solid and robust spine penetrates through the central axis of each arm in some members but is never seen connected to the medullary shell. No structure extends to both sides of the equatorial plane.

STRATIGRAPHIC OCCURRENCE. —Late Middle Eocene-Early Oligocene.

REMARKS

A series of publications by Riedel and Sanfilippo (e.g., Sanfilippo et al. 1985) grouped several genera of both Lithocycliidae and Astracturidae into the single genus Lithocyclia . These were apparently miscategorized with several genera of different stratigraphic ranges. Thus, we are separating more genera than they did for the goal of future discussion. Internal skeletal structure was illustrated for Astromma ( Pisias & Moore 1978: pl. 5, figs 1, 2).

VALIDITY OF GENERA

Astromma

As “ Astromma entomocora ” was wrongly assigned as type species of Astromma by Campbell (1954: D74), this genus was once applied for Didymocyrtis ( Petrushevskaya & Kozlova 1972: 522; Petrushevskaya 1975: 578). Once we disassembled Astromma (= Astracturium in original) and Hymeniastrum from the synonymy of Lithocyclia by Riedel & Sanfilippo (1971: 522), the so-called 50-year rule (ICZN 1999: Article 23.9 “Reversal of precedence”) is not an applicable case for both these genera. Astractura and Astracturium have the same type species and are characterized by four crossed chambered arms, no patagium and a simple medullar shell ( Campbell 1954: D82-83). Astrococcura and Astrococcus have the same type species and can be considered as having a double medullary shell ( Campbell 1954: D83). Staurococcura is characterized by the presence of a patagium and double medullary shells ( Campbell 1954: D84). The lectotype of Astromma found in the Ehrenberg collection ( Ogane et al. 2009b: pl. 71, figs 1a-c) possess a double medullary shell and the different development of the patagium continues from a non-patagium form to a fully-grown form, and, thus, these genera listed here cannot be differentiated at a species level. Astromma is the oldest available name among them (1846 for Astromma ; 1882 for Astractura ; 1887 for Astractinium , Astracturium ; 1896 for Astrococcura and Staurococcura ; 1954 for Astrococcus ).

Amphactura

The same type species was designated for both Amphactura and Amphiactura. The distinction of Diplactinium is suspect because no real specimens assignable to this genus were found during a long time. We simply keep it as valid for a future examination. Diplactinium is characterized by a single medullary shell, no patagium and the presence of a distal spine whereas Amphactura is characterized by the former and double medullary shell with a patagium ( Campbell 1954: D82-83). Dicoccura is defined by the lack of a patagium and the presence of a double medullary shell ( Campbell1954: D83). The synonymy among Amphactura , Diplactinium and Dicoccura is problematic. The lectotype of Amphactura has a high possibility to a broken specimen of Astromma . A different medullary shell is not confirmed for Diplactinium so we have it questionably synonymized with Amphactura . The exactly same morphotypes, excepted for the occurrence of a distal spine on the arms, are commonly found in the same samples so this indicator is not used at genus-level. Like Astromma , the patagium has different growth stages in the same species. The valid name is automatically Amphactura because this genus was the oldest available name among them.

Hymeniastrum

Hymeniastrum was used as a valid genus within 50 years ( Tan 1998: 224; Tan & Chen 1999: 221). Hymenactura and Hymenacturium have the same type species and are characterized by a patagium, blunt and truncated arms, but no terminal spines ( Campbell 1954: D83). Hymenactinium has a patagium and a terminal spine on the distal end of each arm ( Campbell 1954: D83); Trigonactinium is characterized by a patagium and arms with a distal radial spine ( Campbell 1954: D84), and Trigonacturium by arms distally blunt, or truncated, not with a terminal spine ( Campbell 1954: D84). The Nomarski imaging of Hymeniastrum pythagorae for the supporting image of Hymenastrella in the Atlas displays the axial rod which is relevant to the terminal spine inside an arm. As other genera of this family, the patagium as well as the terminal spine on the arm are not characteristic at genus level. The lectotype of Pentactura ( Ogane et al. 2009b: pl. 69, figs 1a-c) confirms the simple drawing of Ehrenberg (1876: pl. 30, fig. 1) with more than five arms. The arrangement of the arms is not such as a cross unlike Astromma so this genus is close to Hymeniastrum . The oldest available names among this group is Hymenastrella (1846 for Hymeniastrum, 1882 for Hymenactura and Pentactura ; 1887 for Hymenastrella , Hymenacturium , Hymenactinium , Trigonactinium and Trigonacturium ).