LOPHOCYRTIIDAE

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 : 519-520

Family LOPHOCYRTIIDAE

Sanfilippo & Caulet in De Wever, Dumitrica, Caulet, Nigrini & Caridroit, 2001

Lophocyrtiidae Sanfilippo & Caulet in De Wever, Dumitrica, Caulet, Nigrini & Caridroit, 2001: 283-284 . — Afanasieva et al. 2005: S300-301. — Afanasieva & Amon 2006: 150.

TYPE GENUS. — Lophocyrtis Haeckel, 1887: 1410 [type species by subsequent designation ( Campbell 1954: D134): Eucyrtidium stephanophorum Ehrenberg, 1874: 233 ].

INCLUDED GENERA. — Aphetocyrtis Sanfilippo & Caulet, 1998: 16 . — Apoplanius Sanfilippo & Caulet, 1998: 12 . — Clinorhabdus Sanfilippo & Caulet, 1998: 19 . — Cyclampterium Haeckel, 1887: 1379 (= Polyalacorys n. syn.). — Lophocyrtis Haeckel, 1887: 1410 . — Paralampterium Sanfilippo, 1990: 307 (= Spongiopodium n. syn.). — Sciadiopeplus Sanfilippo, 1990: 310 .

DIAGNOSIS. — Lophocyrtiidae are commonly three-segmented, cylindrical to conical shell. The cephalis is spherical in shape and may or may not have pores. The cephalic initial spicular system consists of MB, A-, V-, double l-, double L-, and Ax-rods. The double mp - arch (one of AL-arch) freely develops in the cephalic cavity. The A-rod is generally visible and free in the cephalic cavity. It may also be attached to the cephalic wall. The thorax is of a rounded conical shape, thick-walled, and its pores are regularly quincuncially arranged. The abdomen is thick-walled to coarse-framed skirt-like. The abdomen’s end is widely open. The feet, present in some members, are disconnected from the cephalic initial spicular system. The basal ring is directly connected to the apical end of the MB as well as to the double L- and V-rods, forming a frame that resembles a four-leafed clover. The basal ring sharply bends along the line with the double L-rods. The D- and double L-rods extend downward forming a rim on the internal wall of the thorax. These rods are completely merged. A double Dl-arch seems to be present as part of the thoracic wall, but the double l-rod is generally unrecognizable. No living form are known.

STRATIGRAPHIC OCCURRENCE. — Late Paleocene-early Middle Miocene.

REMARKS

The grammatically correct name is “Lophocyrtididae” but the current usage following Article 29.5 of the Code is maintained ( Lophocyrtiidae ).Three segmented, cylindrical Nassellaria similar to the Lophocyrtiidae are known in the Eucyrtidiidae (e.g., Theocoronium ), Rhopalosyringiidae (e.g., Rhopalosyringium ), and Pterocorythidae (e.g., Calocyclas , the Podocyrtopsis -form of Podocyrtis , the Theoconus -form of Pterocorys, Theocorythium ). The most significant difference among them is the presence of a free double mp-arch in Lophocyrtiidae . Theocoronium is of a small size and is more fragile than the Lophocyrtiidae . Rhopalosyringium differs from the Lophocyrtiidae by its artostrobid-type cephalic structure. Calocyclas has a non-bladed, long, robust horn with a spherical and delicate thorax. Both Pterocorys and Theocorythium have a lobe-like, oblong, cephalic part with a complex internal structure. The cephalic structure of the Spongiopodium -form of Paralampterium (Lophocyrtiidae) , similarly to Theoperidae , bears a connection structure between the cephalis and thorax.

According to Sanfilippo (1990), Paralampterium diverged from Lophocyrtis in the early Eocene; Cyclampterium separated around the Eocene-Oligocene boundary while Sciadiopeplus diverged from Cyclampterium just after the appearance of Cyclampterium in the early Oligocene. Lophocyrtis is also the direct ancestor of Apoplanius , this follows the analyses of the stratigraphic distribution as well as the geographic distribution at species level among Lophocyrtis , Apoplanius , Aphetocyrtis and Clinorhabdus ( Sanfilippo & Caulet 1998) . Takemura & Ling (1998) discussed the phylogeny of the Lophocyrtiidae with the same group of species treated inSanfilippo & Caulet (1998). These species appear under the genus name Theocorys Haeckel 1882 (with a Mesozoic type species Theocorys morchel- lula Rüst, 1885), as some photos appear to have a double mp -arch ( Takemura & Ling 1998: fig. 3.19). Little is known about the ancestor of the Lophocyrtiidae .

The morphological change of the cephalic initial spicular system at species level was documented for Aphetocyrtis , Apoplanius and Clinorhabdus ( Sanfilippo & Caulet 1998) . The double mp -arch must be encrypted in the cephalic wall of some members as it remained unobserved in scanning electron microscopy (SEM) images ( Takemura & Ling 1998: figs 5.7-5.12). The double mp -arch is recognizable as part of the thoracic wall in SEM illustrations of Aphetocyrtis (originally Theocorys in Takemura & Ling 1998: figs 5.11, 5.12), Clinorhabdus (originally Theocorys inTakemura & Ling 1998: figs 5.9, 5.10) and the Spongiopodium form of Paralampterium ( Nishimura 1990: figs 27.1-27.3).

VALIDITY OF GENERA

Cyclampterium

Polyalacorys was first practically validated by Nishimura (1990: 142), who subsequently designated Alacorys carcinus as the type species of Polyalacorys , whereas Cyclampterium was transferred from a subgenus of Cycladophora ( Haeckel 1887: 1379) to that of Lophocyrtis (Sanfilippo 1990: 304) . Sanfilippo (1990) described Cyclampterium as having an apical horn usually short or absent and Nishimura (1990) described it as an apical spine prolonged from an A-rod. The length of the apical horn is the only difference in these descriptions. Sanfilippo (1990) considered the Cyclampterium lineage to start from Lophocyrtis (Cyclampterium) hadra . This species has a very long, stout apical horn that nearly reaches the same length as the apical horn of Alacorys carcinus , the type species of Polyalacorys . Based on the lineage reconstructed by Sanfilippo (1990), Polyalacorys must be synonymized with Cyclampterium. Cyclampterium has been raised to the rank of genus for practical usage due to its significant morphological differences, although this genus branches from Lophocyrtis .

Paralampterium

The main difference between the definitions of Spongiopodium and Paralampterium is a spongy wall structure and three or more foot-like projections for the former ( Nishimura 1990: 135); the abdominal segment, the most conspicuous one, is very variable, with large-coarse meshes and three feet that are solid, incipiently latticed or pored for the latter (Sanfilippo 1990: 307). The definition of Paralampterium covers that of Spongiopodium, which raises the issue of splitting and lumping philosophies. The genus concept by Sanfilippo (1990) is based on stratigraphic and geographic distribution at the species level, whereas that by Nishimura (1990) is based on a spot sampling obtained in just one locality of the Pacific Ocean. As Sanfilippo’s (1990) concept better reflects stratigraphic and geographic variation for this taxon, we support the lumping philosophy for this genus. Both genera were published in 1990; the formal publication dates were March 1990 for Paralampterium (Marine Micropaleontology, Volume 15 no. 3-4) and March 31, 1990, for Spongiopodium (Science Reports of the Institute of Geoscience, University of Tsukuba, Section B: Geological Sciences, Volume 11). Because there is no clear difference between these publication dates, we select Paralampterium as the valid name due its more comprehensive definition.