New species of Neogene radiolarians from the Southern Ocean – part III

In this paper, the third of a series of four, 25 new species are described from the Neogene sediments of the Southern Ocean: six spumellarians (Actinomma telarania, Hexacontium? cooki, Lonchosphaera shackletoni, Joergensenium pseudodictyocha, Cryptolarnacium pauliani and Spongoplegma dentifrangibula) and nineteen nassellarians (Arachnocorallium cerebellum, A. stilla, A.? pyroensis, Amphiplecta? satoshii, Antarctissa kjelli, Lithomelissa celsagula, Botryopera piperata, B. vavato, Lophophaena? neuma, L.? globeacuculla, L. pileata, L. amictoria, Pseudodictyophimus ignatius, Spongomelissa? bipatens, Ceratocyrtis? arthuri, C.? ringisstola, Phormostichoartus ashbyi, Ceratospyris clinamen and Dorcadospyris kennetti).

below. The Riedel (1967) classification is based on highly distinct structural features (Baupläne) of the complete shell. Although a more recent, inferred ontogeny-based taxonomical framework has been proposed (De Wever et al., 2001), some authors are in disagreement with it (e.g. Lazarus et al., 2005;Suzuki & Aita, 2011). Molecular-based classifications of radiolarians, which can perhaps better resolve higher-level relationships, are still in their infancy.
Because this work is only about species-level taxonomy we prefer to follow the conservative, less controversial classification of Riedel (1967) whenever possible. The terminology used here follows mostly Jørgensen (1905) and Petrushevskaya (1965Petrushevskaya ( , 1968 for nassellarian internal structure (Fig. 3), Goll (1968) for features specific to the family Trissocyclidae and Boltovskoy (1998) for general external characters. The notation for connecting arches in nassellarians follows generally De Wever et al. (1979), Dumitrica (1991) and Funakawa (1995a) in which they are named after a combination of the initials of the spines from which they originate (i.e. arch aV would be an arch connecting spine a and spine V, see Fig. 3a) or, when necessary, follows Petrushevskaya (1965Petrushevskaya ( , 1968 in which they are named after the apophyses they are joining (i.e. arch mj joins apophyses m on spine a and j on spine V, see Fig. 3b).
All holotypes are deposited in the micropalaeontology collection of the Museum für Naturkunde (MfN), Berlin (MfN accession numbers eCO-xxx). Specimens are identified by a circle on the slide. All discussed specimens are illustrated in Plates 1-8.  Jørgensen, 1905). a: apical spine; V: ventral or vertical spine; d: dorsal spine; lr and ll: primary lateral right and left spines; l': secondary lateral spines; Mb: median bar; ax: axobate; aV: arch connecting spine a and spine V. Dark grey: spines in the sagittal plane (i.e. the plane of a, Mb, d and V); black: spines on our side of the sagittal plane; dashed, light grey: spines on the other side of the sagittal plane. (b) Apophyses (modified after Petrushevskaya, 1971). g: galear; m: mitral; a: anterior; t: tergal; c: cervical; p: pectoral; j: jugal; d: second series of apophyses on spines ll and lr; mj: arch connecting apophyses m and j.
shell ratio. It is distinguished from other actinommids in the presence of an outer cortical shell, and from the species described as Cromyechinus icosacanthus Haeckel, 1887, C. dodecacanthus Haeckel, 1887and C. circumtextum Haeckel, 1887 primarily in its long conical spines but also in the pore patterns of its shells and, for C. circumtextum, in its shell ratio.
Differentiation between immature (juvenile) specimens of this new species and immature specimens of Sphaeroyple robusta Kling, 1973 could be problematic as the three first shells are remarkably similar in both those species (see, for instance, Suzuki, 2006, fig. 11), the only true difference at this stage being the long conical spines of A. telarania that seem to appear quite early in the ontogeny of the species: the specimen in Plate 1, fig. 1A-B, whose outermost cortical shell has just started to form, already possesses fully developed conical spines. More juvenile specimens were not recognized in our material, making it difficult to judge when this character appears in regard to the formation of the third shell.
diagnosis. Large and thick-walled, slightly flattened spherical shape, cortical shell with large pores; six radial beams; numerous thorns.
description. Large three-shelled actinommid with a shell ratio of approximately 1:2.5:10. Cortical shell is thick, with a circular to somewhat flattened circular outline, and is covered with fairly long, conical thorns arising from bar nodes. Pores on the cortical shell are large and closely packed (see Pl. 3, fig. 4A); they are elliptical to irregular in shape. Outer medullary shell has a somewhat flattened circular outline (see Pl. 3,. Pores in the medullary shell are small, closely packed (usually arranged in a hexagonal pattern; Pl. 3, fig. 7) and polygonal. Inner medullary shell seems to be a polyhedron (Pl. 3, figs 5-6). Six radial beams arise from this polyhedron, join the outer medullary shell, where they become tribladed, extend to the cortical shell and then protrude as conical spines of same length and shape as the numerous thorns covering the cortical shell. remarks. This species shares many common features with Actinomma golownini Petrushveskaya, 1975(= A. tanyacantha Chen, 1975; concerning the priority between Chen (1975) and Petrushevskaya (1975) species names, see Lazarus (1990, p. 710)) such as the shape, size and porosity of their medullary shells and their cortical shell outline. However, they differ in A. golownini having a thinner cortical shell bearing four supplementary spines similar to the six radial ones and in H.? cooki having a thick cortical shell bearing numerous thorns and being larger. This species is also very similar to the Arctic species Hexalonche esmarcki Goll & Bjørklund, 1989 but varies from it in its larger, thicker and 'thornier' cortical shell. Pores on the cortical shell of H.? cooki are also more regularly disposed and its outer medullary shell is flattened. It also differs from Actinomma haysi Bjørklund, 1976b, in possessing numerous thorns, in the shape of the cortical and outer medullary shells and in the conical spines. The cortical shell of H.? cooki is also comparable to that of Cenosphaera cor onatoformis Shilov, 1995 and Pentactinosphaera hokurikuensis (Nakaseko, 1955) in its size, thickness and the shape and disposition of its pores; it differs, however, from these species in the presence of numerous thorns and in their outer medullary shell being, in C. coronatoformis, non-existent or, in P. hokurikuensis, a heteropolar, pyriform meshwork of thin bars. Finally, it differs from Haliomma? immensa Kozlova in Petrushevskaya & Kozlova, 1979 primarily in the radial beams being, in the latter, irregularly distributed and thin as well as conical, and from Haliomma? extima Petrushevskaya in Petrushevskaya & Kozlova, 1979 in the shell ratio, the greater irregularity in the pore disposition in the latter and the outline of the cortical shell.
Because of its three-shelled skeleton and its six radial beams, H.? cooki was tentatively assigned to the genus Hexacontium; however, the tetrapetaloid structure of the inner medullary shell, typical of that genus, could not be observed due to the thickness of the cortical shell. This generic assignment is also problematic considering the fact that the genotype (H. phaenaxonium) was not illustrated by Haeckel and not found during the exploration of Haeckel's material .
As is summarized in Burridge & Bjørklund, (2014, p. 78), there is something of a controversy as to whether some Cenozoic and Quaternary genera (including the genera Hexacontium, Pentactinosphaera, Lonchosphaera and Joergensenium that we mention in this series of papers) should be considered to be entactinarians or spumellarians: while some authors (e.g. Dumitrica, 1985;De Wever et al., 2001) think their innermost medullary shell structure is homologous with the spicular inner shell of the entactinarians, other authors (e.g. Suzuki & Aita, 2011) tend to think that the order entactinaria became extinct during the Mesozoic. While we do recognize the Cenozoic family Orosphaeridae to be a possible member of the order entactinaria (as indicated in Renaudie & Lazarus, 2012), we are not convinced that the innermost shell of the Cenozoic genera mentioned above and the spicular inner shell of the entactinarians are indeed homologous. It is probable that studies on molecular phylogeny of radiolarian families will help in clarifying the matter in the near future, but in the meantime we prefer to think of those genera as belonging to the Spumellaria.
Genus Joergensenium Bjørklund et al., 2007 Fig. 4. Schematic representation of the medullary shell of: (a) Lonchosphaera spicata Poposfky, 1908(modified after Petrushevskaya, 1975 description. Small globular outer shell consisting of a meshwork of thin, anastomosed bars diverging from the small, thin spines extending from the silicoflagellate-looking, spicular inner medullary shell, which consists of a somewhat hexagonal ring from which arise six radial beams (in the plane of the ring; Pl. 1, fig. 7A; Fig. 4), and of three (Pl. 1, fig. 5B) bars starting from opposite sides of the ring and joining in the middle where one (two?) beam(s) arises perpendicularly to the plane of the ring (Pl. 1, fig. 5A). The shell ratio is approximately 1:2. Some small, thin by-spines arise from some bar nodes of the outer shell, but do not seem to be connected with the inner medullary shell (Pl. 1, figs 4A, 5B, 7B). Pores on the outer shell are polygonal (generally pentagonal or hexagonal; Pl. 1, figs 4B, 7B) and relatively large compared to the thickness of the bars separating them. There are generally 6 to 8 such pores on a half-equator. remarks. This species differs from Lonchosphaera spicata, L.? suzukii and L. shackletoni in its highly reduced size and its subsequently high shell ratio. The outer shell wall is otherwise very similar to that of L. spicata. J. pseudodictyocha shares many features with Sethostaurus parvulus Popofsky, 1912 (size, shell ratio, shape and porosity of the outer shell) but differs from it in lacking the four long tribladed spines arising from the radial beams of S. parvulus. It differs also from Melittosphaera magnaporulosa (Clark & Campbell, 1942) in the latter having a properly latticed cortical shell wall and a spherical, latticed-wall medullary shell; from Haliomma sp. Tan, 1993 in lacking the long radial spines and by-spines; from Actinomma cocles Renaudie & Lazarus, 2013 in its spicular medullary shell. Actinomma(?) sp. B Hull, 1996 (pl. 1, figs 3-4, 9, 12) seems to have the same medullary shell as J. pseudodictyocha and their cortical shell are also very similar; however, the specimen in Hull, (1996) has a lower shell ratio and longer, more numerous spines.
J. pseudodictyocha is very similar to the medullary shells of J. rotatile Bjørklund et al., 2007 andJ. appolo Kamikuri, 2010; however, it differs from them quite clearly in their outer medullary shell consisting of seven cupolas, whereas the external shell of J. pseudodictyocha is simply spherical to slightly globular and does not show such cupolas.
Because of their size, it is possible that the two shells of this new species are indeed an outer and an inner medullary shell. Whether this species lacks a cortical shell or all specimens observed are juvenile or broken cannot be determined with certainty.
Genus Lonchosphaera Popofsky, 1908 type species. Lonchosphaera spicata Popofsky, 1908. diagnosis. Large irregular-pored cortical shell; polyhedral medullary shell with radial beams extending externally as long, tribladed spines. Material. eight specimens observed in samples from ODP sites 690 and 1138. description. Large, spherical cortical shell with rough surface and numerous pores that are irregular in size, shape and randomly arranged. The bars between pores are rather thin. Cortical shell bears numerous thorns. A small number (two to eight) of long, tribladed spines also protrude from the cortical shell. They originate directly from the beams (text- fig. 4c) arising from the small irregular polyhedral medullary shell. In some specimens, a very thin meshwork links the beams somewhere between the cortical and medullary shells. remarks. The medullary shell of Lonchosphaera shackletoni seems to be exactly similar to the one illustrated for L. spicata by Petrushevskaya (1975, pl. 17, fig. 8), hence the generic assignment. Although L. shackletoni is also very similar in structure with the specimens illustrated by Petrushevskaya (1975) as L. sp. B and L. sp. C (respectively her pl. 17, figs 9-10 and 11-15), the size of the cortical shell, the medullary to cortical shell ratio and the shape of the radial beams in these species are very different. L. shackletoni and L.? suzukii Renaudie & Lazarus, 2013 differ in the size of their cortical shell, in the tribladed radial spines and in the pore to bar area ratio of the cortical shell. The cortical wall in L.? suzukii is furthermore properly latticed whereas it is somewhat anastomosed as a 3D mesh in L. shackletoni. Additionally, it differs from the specimen illustrated as Octodendron hamuliferum Hollande & enjumet, 1960(in Tan, 1993 fig. 3 non figs 1-2) in the size of the cortical shell and in the radial spines being in the latter larger and serrated, with many small apophyses branching regularly from them. description. Two concentric shells consisting of a thick, latticed cortical shell and a medullary meshwork connected together by a fairly high number of rather thin, cylindrical (rarely bladed) radial beams. There is a depression on the cortical shell where each radial beam fuses with the shell, thus creating a 'bumpy' surface.
Pores on the cortical shell are rounded to elliptical, of variable size (but somewhat large) and unevenly distributed. They are separated by thick, cylindrical bars. The medullary meshwork is twice as small as the cortical shell and is somewhat dense. It has a general spherical shape but has a cupola-shaped extension where the radial beams arise. It seems that the very centre of this medullary meshwork is denser and has a more regular geometrical pattern; but, due to the already substantial density of the outer meshwork, it is difficult to observe it. occurrence. Sporadic from the Tau to the Phi zone (early Pliocene to Pleistocene), common from the Phi to the Omega zone (Pleistocene to Holocene).
remarks. S. dentifrangibula differs from Spongoplegma antarcti cum Haeckel, 1887, S. medianum (Nigrini, 1967) and S. arcado phorum (Haeckel, 1887) in having a thick, latticed cortical shell (compared to a thin meshwork of anastomosed bars). It also differs from S. variabile Nakaseko, 1972 in having a thicker wall, bigger, unequal pores, a smaller but denser medullary meshwork and a 'bumpy' surface. It differs from S. holtedahli (Bjørklund, 1976a) and S. nipponicum (Nakaseko, 1955) primarily in having a single cortical shell; from Rhizosphaera serrata Haeckel, 1887 and Haliomma capillacea Haeckel, 1887 in its thick cortical shell with wider bars between pores and its larger, denser medullary shell; from Actinomma gigantea Popofsky, 1912 in lacking external spines, in the diameter of its cortical shell (more than 200 µm in A. gigantea; Popofsky, 1912) and in the lower number of radial beams. The specimen illustrated as Spongoplegma sp. Chen (in Lazarus, 1992, pl. 5, figs 3-4), although weakly silicified compared to our specimens is likely to be conspecific with our new species. The specimen illustrated by Chen (in Lazarus, 1992) on plate 5, figs 1-2 as well as the specimens illustrated as Spongoplegma sp. Chen (1975, pl. 22, figs 1-2), although having a slightly irregularly shaped spherical outline, does not seem to have a bumpy surface; they also are more regularly pored, thinner-walled, with a lower shell ratio: they probably both belong to species Spongoplegma variabile Nakaseko, 1972 despite the irregularity of their shell outline.
Family Pyloniidae Haeckel, 1881Genus Cryptolarnacium Dumitrica, 1989 type species. Cryptolarnacium hexastylus Dumitrica, 1989. description. Small two-shelled skeleton from which arises four very long (up to 180 µm), conical spines. Four additional spines arising also from the medullary shell can be seen on some specimens: these are situated at the bisector of the previously mentioned spines and are considerably smaller and thinner (so much so that they are hardly distinguishable from the other by-spines; Pl. 3, fig. 3A-B). Cortical shell is spherical to ellipsoidal, with small, regularly arranged circular pores and a fair amount of medium-lengthed byspines. Incompletely formed cortical shells appear to be of pyloniid origin (Pl. 3, fig. 1A-B). The medullary shell has an oblong outline and seems to be a pyloniid medullary shell with two opposite gates (Pl. 3, figs 1B, 3B). Radial beams extend from it and protrude outside the cortical shell as long conical spines with a thickened base. occurrence. Sporadic from the Cycladophora spongothorax zone to the Chi zone (Late Miocene to Pleistocene).
remarks. Cryptolarnacium pauliani differs from Larnacalpis sp. A Suzuki et al., 2009b, from Larnacalpis sp. 2 Dumitrica, 1989 and from Larnacilla? spp. Dumitrica, 1989(Dumitrica, 1989, non 3 and 5) in its long conical spines arising from the medullary shell; from Larnacalpis sp. Takahashi & Honjo, 1981 and from Larnacalpis sp. 1 Dumitrica, 1989 in its more or less spherical outline; and from Tetrapyle octacantha Müller, 1858 in the presence of a cortical shell and of spines. It is also distinguished from Echinomma sphaerechinus Haeckel, 1887, Drymyomma elegans Jørgensen, 1900 and Actinomma cocles Renaudie & Lazarus, 2013 in its pyloniid medullary shell and in its long conical spines. Finally, it differs from the type species of the genus, the eocene C. hexastylus, in its thinner cortical shell, bearing larger pores, in its numerous by-spines and in the possession of four (instead of six) longer radial spines. Not only does the shell ratio seem lower in C. hexastylus, but the overall size of C. pauliani is also much less than C. hexastylus (c. 65 µm v. c. 160 µm for the cortical shell.).
Phormostichoartus ashbyi n. sp. though the lineation on thoracic pores is less regular than on the two following segments. Pores of equal diameter on all segments except on cephalis (where they are smaller).
occurrence. Common from the Acrosphaera? labrata zone to the Tau zone (Late Miocene to early Pliocene), sporadic from the Tau to the upsilon zone (early Pliocene).
remarks. It differs from Phormostichoartus corbula (Harting, 1863), P. fistula Nigrini, 1977 andP. pitomorphus Caulet, 1986 in its shell outline, in the smaller number of pore rows per segment and in the length and breadth ratio of the abdomen v. the post-abdominal segment. It differs from other artostrobiids, and in particular from Botryostrobus aquilonaris, in its lower number of segments and the downward direction of its ventral tube. Phormostichoartus sp. A Ashby, 1986 (unpublished thesis, victoria university of Wellington) differs from this new species only in the inflexion of the outline being on the post-abdominal segment instead of on the abdomen, as is the case in this new species.
Material. Thirty-five specimens observed in samples from ODP sites 748 and 751.
description. Dicyrtid with a long, apically-elongated cephalis (some specimens have a somewhat flattened apex; Pl. 5, figs 10-11) and a short, largely flaring thorax. Shell wall is smooth with randomly arranged, well-spaced, small, circular to elliptical pores. A large number of small thorns connected to one another are present at the apex of the cephalis including one broader thorn connected to spine a (see Pl. 5, fig. 11). Spine V is short, and can protrude at the collar stricture as a very short triangular horn (Pl. 5, fig. 10). In some specimens (such as in Pl. 5, fig. 11 and Pl. 8, fig. 11), apophyses j are strongly expressed and bifurcate, one upward, the other downward just before spine V connects to the wall. Spine a is fused to the dorsal part of the cephalic wall. An arch ad is well developed, thus creating a small shoulder. Spine d seems to bear some dents (Pl. 8, fig. 11) in addition to apophyse c which is thin and connects to the arch near its middle. ax is sometimes seen as a small dent of Mb. Spines ll and lr join Mb close to spines a and d (Pl. 8,fig. 11) and project subhorizontally, almost perpendicularly to the sagittal plan (hence the flaring of the upper thorax). They do not form wings. Arch Vl can be seen in some rare specimens as a thin rod. Although the cephalis and the thorax are separated by arches al and Vl, there are no visible furrows along those arches. Arch al is not distinct but may be embedded in the wall. remarks. It differs from Amphiplecta tripleura Funakawa, 1995b in the width/length ratio of its cephalis, in having less numerous, smaller pores as well as a smoother shell wall and in the dorsal shoulder being less developed but covered by the shell wall; from A. cylindrocephala Dumitrica, 1973 in the thickness of its wall, the shape of its cephalis and in having less numerous, smaller pores. Contrary to what is seen in A. tripleura and A. acrostoma Haeckel, 1887(Petrushevskaya, 1971Funakawa, 1994Funakawa, , 1995b, arch dl (or d-al according to Funakawa 1995b) is not recognizable in our species, and arch al is not distinguishable from the rest of the wall. This renders the genus assignment questionable; however, the fact that arch ad is clearly expressed as a bump external to the rest of the cephalis and the overall shape of the cephalis seems to indicate a close relationship of A.? satoshii with those two species.
Amphiplecta? satoshii also differs from Lophophaena galeata ehrenberg, 1874 (see also Ogane et al., 2009, pl. 79, fig. 1a-c) and L. capito ehrenberg, 1874 (see also Ogane et al., 2009, pl. 79, fig. 2a-c) in its elongated cephalis with a flattened top, the presence of a cluster of apical spines instead of just a unique spine and, more importantly, in its inner cephalic structure: L. galeata seems, based on the Ogane et al. (2009)  diagnosis. Strawberry-shaped cephalis with, apically, a cluster of supplementary horns; characteristic thorax termination with numerous ridges prolonged as feet, and a large hemispherical, thin sieve plate.
Material. Seven specimens observed in samples from ODP site 747.
description. Large dicyrtid with a cephalis elongated toward its somewhat blunt apex and a long thorax with a short flaring upper part and a lower part in the shape of a pinched cylinder (i.e. a hyperboloid) or, in later form, a proper cylinder (see Pl. 7, fig.  15). Thorax end with several ribs projecting as long, thin teeth. Below this termination is a large, thin, mainly concave sieve plate, perforated by numerous, closely packed, elliptical to polygonal pores.
Spines a and V join the wall at the collar stricture. The cephalis, however, exhibits a cluster of apically situated horns (unrelated to any internal spines or apophyses). Spine d is projected downward and bears an upward-directed apophyse c (evoking a similar disposition typical of genus Antarctissa; compare Pl. 8, fig. 10 with Petrushevskaya (1967, pl. 49, fig. 3)). Spines d, ll and lr join the thoracic wall between the upper and the lower thorax and continue outside as short needle-like wings. Spine ax is situated at the middle of Mb and is fairly long and straight (Pl. 8, fig. 10). Pores on the cephalis are small, of more or less even size and slightly elliptical. Pores on the thorax are generally larger and more unevenly spaced as well as uneven in size. Cephalic wall is thicker and the bars between the pores more frankly crested than on the thorax. remarks. Although the overall shape of the species as well as the thorax termination are very uncharacteristic of the genus Antarctissa, the fact that spine a, in particular, joins the cephalis wall at the level of the external collar stricture, and the shape and direction of spine d together seem to be characters strong enough to justify the assignment of this species to the genus. This species differs from Antarctissa strelkovi Petrushevskaya, 1967 in the shape of the cephalis, the length of the thorax and its peculiar termination. Although Antarctissa strelkovi and A. evanida Renaudie & Lazarus, 2013 also have clusters of apical horns (systematic in evanida but rarer in strelkovi), they are, in those two species, conical whereas in A. kjelli they are often linked together by blade-shaped connections (see Pl. 7, fig. 12). Finally, this species differs from Helotholus praevema Weaver, 1983 in the shape of its cephalis (H. praevema cephalis being almost hemispherical), in the shoulders of the latter being twice as wide as its cephalis and in the spines d, ll and lr of H. praevema joining the wall at the shoulder and never extending outside as wings.
diagnosis. Large, almost spherical, cephalic chamber; strong spines d, ll and lr that branch irregularly in their distal part; several long, subapical by-spines.
Material. 1396 specimens observed in samples from ODP sites 689, 690, 693, 745, 746, 747, 751 and 1138. description. Shell consists only in a cephalis which is in two distinct parts: a large, spherical, almost globular upper part that bears regularly arranged, relatively large circular pores and whose wall is rough and crested and a more or less conical, narrow lower part with a few large circular pores and a rather smooth wall. Spine a is embedded in the wall of the lower and the upper part and eventually, in some specimens, protrudes as a fairly long conical spine (Pl. 5, fig. 2). Spines d, ll and lr are rather strong, relatively long and bifurcate distally. ax can be seen near the junction of Mb, ll and lr as a triangular dent on Mb. Several supplementary thin, long, conical horns can also be present subapically. occurrence. Rare from the upper Cycladophora spongothorax zone to the Tau zone (Late Miocene to early Pliocene), common from the Tau zone to the Phi zone (early Pliocene to Pleistocene). Funakawa, 1995b in the presence of the long by-spines and in the robustness, length and shape of the basal spines. It is also distinguishable from the specimen illustrated in Petrushevskaya (1971) as Lophophaeninae gen. sp. cf. Micromelissa coarctata Rüst, 1888 by its size, its numerous, larger pores and the additional spines being confined to the apical part of the cephalis. Psilomelissa? sp. A Hollis, 2002 is lacking an apical horn, has longer, tribladed d, ll and lr spines and lacks the basal constriction of the cephalic chamber.
Material. 336 specimens observed in samples from ODP sites 689, 690, 693, 745, 747, 748, 751, 1138. description. Shell consists only of an apically elongated tearshaped cephalis. Pores are circular to elliptical, generally large, irregularly arranged. Shell wall is rough and numerous spine-like thorns arise from bar nodes. Spines a and V (Pl. 5, fig. 3) are incorporated in the shell wall but do not seem to protrude as horns (or they are not distinguishable from the numerous thorns). Spines d, ll and lr are fairly long, conical and can bifurcate close to their base (Pl. 5, fig. 5). ax is not noticeable.
occurrence. Common from the Actinomma golownini zone to the Acrosphaera australis zone (Middle to Late Miocene), then rare until the Tau zone (early Pliocene) and finally sporadic until the upsilon zone (Late Pliocene).
remarks. It differs from Peridium infundibuliforme (Funakawa, 1995b) in its upper cephalis bearing numerous spines, being crested, with a smaller number of pores. This new species also differs in spines d, ll and lr being more robust and longer than in P. infundibuliforme. It is also distinguished from Plectacantha oikiskos Jørgensen, 1905, Arachnocorys dubius Dogiel in Dogiel & Reshetnyak, 1952, Plectacantha cresmatoplegma Nigrini, 1968 and Plagiacantha panarium Dumitrica, 1973 primarily by those species' cephalic wall being only a thin meshwork spread between a series of spines connected to Mb and directed upwards and not a proper eucephalic chamber as in A. stilla. It differs from Peridium longispinum Jørgensen, 1900 (see also Bjørklund 1976a, pl. 7, figs 9-15) in its elongated cephalis, thicker bars, shorter spines and in being much larger (c. 80 µm v. c. 45 µm); and from Peridium piriforme Popofsky, 1908 also in its larger size (P. piriforme is c. 60 µm) and, more importantly, in its basal spines (d, ll and lr) being shorter and lacking the many distal branches that Popofsky described and illustrated for P. piriforme. It is finally distinguished from Arachnocorallium calvata (Haeckel, 1887) by its numerous thorns/spines and in its elongated cephalis.
The specimen illustrated on Plate 5, fig. 5A-B possesses a thin, unfinished thoracic wall, connected to spines d, ll and lr but also to some thorns on the lower third of the cephalic wall (i.e. where the cephalis outline starts to narrow). This growth stage is reminiscent of what has been shown for Arachnocorallium calvata in Petrushevskaya, (1971, pl. 70, figs 1-8); however, in A. calvata, some branchings seem to connect the thorax wall to the upper third of the cephalic wall as well, in an early stage of the thorax development (Petrushevskaya, 1971, pl. 70, fig. 7), whereas here there is no trace of such connections in our specimens of A. stilla.
(Pl. 5, figs 6A-B, 8-9B) derivation of name. From the Latin Pyrois which is another name for the planet Mars, with termination -ensis meaning 'from', pyroensis therefore stands for 'Martian' after the resemblance of the specimen seen in apical view (Pl. 5, fig. 6A-B) with the depiction of Martians in 1960s science fiction.
diagnosis. Cephalis wall is a loose meshwork attached to a sagittal ring; spines d, ll and lr are long and thin.
Material. 412 specimens observed in samples from ODP sites 751 and 1138.
description. Monocyrtid with a cephalis arranged on both sides of a clearly developed sagittal ring (i.e. a, V and arch Av; see Pl. 5, fig. 9B). This sagittal ring apex is orientated ventrally. Spines d, ll and lr are well developed, long, thin and conical. A supplementary spine projects from spine a dorsally as a short conical horn. ventrally, a triangular dent can be seen high on spine V. Shell wall is loose, consists of a few large, elliptical pores separated by crested bars. In apical view (see specimen Pl. 5, fig. 6A-B), the shell has a cardioid outline due to a constriction following spine a. The breadth (perpendicularly to the sagittal ring) seems on this specimen slightly greater than its width (parallel to the sagittal ring).
occurrence. Common in the Acrosphaera australis zone (Late Miocene).

remarks.
Despite having what seems to be a sagittal ring, this species is unlikely to be a trissocyclid due to the absence of a basal ring. It differs from members of the genus Zygocircus Bütschli, 1882 and the genus Cortina Haeckel, 1887 in possessing a shell wall and in its well-developed spines d, ll and lr. It differs from members of the genus Arachnocorallium in possessing a sagittal ring. The generic assignment is therefore provisional and based on the postulate that the presence of the sagittal ring in this species is only a convergence with the sagittal ring seen in the Trissocyclidae sensu Goll (1979), the Acanthodesmiidae sensu Petrushevskaya (1971) or even the Stephaniidae sensu Nishimura (1990  description. Dicyrtid with a hemispherical cephalis (c. a third of the shell height) and a truncated conical thorax. Both segments are separated externally by furrows following arches al and Vl (Pl. 7, fig. 6). Spine a is fused to the dorsal side of the cephalic wall and protrudes subapically as a short triangular, tribladed, slightly incurved, robust horn. Spine V protrudes at the collar stricture as a shorter, triangular and tribladed horn. Spines d, ll and lr join the thoracic wall, are directed downwards (and eventually form furrows on the thoracic wall; Pl. 7, fig. 6) and continue after the thorax termination as small feet. These feet are short and conical and are undifferentiated from the fairly numerous teeth that also project at the thorax termination. The mouth is closed by a sieve plate, relatively thick, perforated by a few, randomly distributed, small circular pores (Pl. 7, fig. 9A). Additional robust spines can be present on the cephalis (Pl. 7, figs 6, 8). The shell wall is generally rather thick. Pores on the cephalis are small and circular while pores on the thorax are somewhat larger. remarks. This species is easily distinguished from other species of Botryopera because of the presence of basal teeth and of a sieve plate closing the basal aperture. The thickness of the shell and the short, robust horns are also characteristic of this species. In particular, it differs from Botryopera chippewa Renaudie & Lazarus, 2013 in the cephalis to thorax height ratio, in its shell outline and the shape and length of the apical horn. It differs from Pseudodictyophimus gracilipes Bailey, 1856 (and in particular to the form described as Pseudodictyophimus gracilipes bicornis (ehrenberg, 1861); see Petrushevskaya (1967, pl. 41, figs 1-5), Suzuki et al. (2009a, pl. 45, fig. 8a-d)) and from Trisulcus nanus (Popofsky, 1913) emend. Petrushevskaya, 1971 in the absence of wings, the length of the apical horn, the shell thickness and the less-marked shoulders. Cephaluspinus josephinus Alvira Martin, 1971 seems to be very similar to B. piperata as they share their thorax shape and most noticeably their peculiar thorax termination, but they differ in C. josephinus having thin, long apical and vertical spines and a more pronounced change of contour at the collar stricture (judging by the specimen illustrated in Alvira Martin, 1971, pl. 3, fig. 2). The specimen illustrated as Botryopera? pseu doantarctissa Petrushevskaya & Kozlova, 1979in Hull (1996, figs 3-4) seems similar to B. piperata but lacks a sieve plate and robust horns (which can be due to preservation or ontogeny) and has larger, polygonal pores. B. pseudoantarctissa as described and illustrated in Petrushevskaya & Kozlova (1979) is distinguishable from this new species primarily in having a straight, cylindrical thorax and lacking horns. B. piperata finally differs from Botryopera? chlamyda Petrushevskaya, 1975  remarks. This species is characterized by its wings and its more or less cylindrical, closed thorax. The furrows along arches al and Vl, the shape of the cephalis and the disposition of spines a and V relative to the shell wall seem to be characteristic of this group of small dicyrtids that we have regrouped in this series of papers (Renaudie & Lazarus 2012, 2013 inside the genus Botryopera (with the exception of Botryopera? daleki Renaudie & Lazarus, 2013 as explained in the Remarks for that species).
This species differs from B. piperata and B. chippewa Renaudie & Lazarus, 2013 in its fairly long thorax, its short, weak apical spine and its wings; from Lithomelissa buetschlii Haeckel, 1887 primarily in its wall thickness, in the length of its cephalis and thorax and in the cephalis/thorax ratio; from Dimelissa apis Petrushevskaya, 1971 and the specimens illustrated as Lithopera oceanica ehrenberg group in Petrushevskaya (1975, pl. 19, figs 4-5) in its long, cylindrical thorax; from Trisulcus nanus (Popofsky, 1913) emend. Petrushevskaya, 1971 primarily in lacking the deep furrows along spines d, ll and lr at the collar stricture; from Lithomelissa setosa Jørgensen, 1900, in the presence of wings, the less marked shoulders and the modest yet present apical horn; from Lophophaenoma arctissa Petrushevskaya in Petrushevskaya & Kozlova, 1979 in the latter having a thicker shell wall and bearing fewer pores (specimens illustrated in Petrushevskaya & Kozlova, 1979, figs 339 and 342), in the wings (if any) being poorly developed and in the cephalis-thorax length ratio; from the specimen illustrated as Botryopera laticeps? (Jørgensen) in Petrushevskaya (1975, pl. 20, fig . 3) in the cephalis/thorax ratio and the thorax width; from Antarctissa deflandrei Petrushevskaya, 1975(= Antarctissa conradae Chen, 1975 in the explanation of Plate 5. fig. 1. Arachnocorallium cerebellum n. sp. Sample 120-747A-4H-1, 45-47 cm. fig. 2. Arachnocorallium cerebellum n. sp. Sample 120-751A-4H-4, 98-102 cm. Holotype. fig. 3. Arachnocorallium stilla n. sp. Sample 119-745B-14H-6, 53-55 cm. Holotype. fig. 4. presence of wings, in the latter's spine a joining the cephalic wall at the collar stricture, and in its cephalis apex being round instead of elongated into a peak as in A. deflandrei. description. Small dicyrtid with a cephalis and a thorax indiscernible externally. Thorax seems to be closed by a sieve plate (Pl. 6, fig. 4A). Pores on the shell wall are irregular in size, shape (though usually polygonal) and disposition. Mb is reduced to a point from where all spines (a, V, d, ll and lr) project upwards and protrude outside the wall as short conical horns. Some additional spines are present on the cephalis and some of them may be related to apophyses (see Pl. 6, fig. 6B). The point where all spines converge, i.e. Mb, is situated halfway down the shell cavity, meaning that, technically, the cephalis and the thorax are of equal length. occurrence. Sporadic from the Cycladophora golli regipileus zone to the upsilon zone (early Miocene to early Pliocene).

Genus
remarks. Because of the thorax termination and the cephalis length and because the axobate was not observed, the generic assignment of this species to Ceratocyrtis is tentative. The fact that there is no discernible collar stricture and that Mb is reduced to a point make us lean toward this assignment. Clathromitra pterophormis Haeckel, 1887 and Clathromitra pentacantha Haeckel, 1887 also have a highly reduced Mb and a domeshaped shell; however, they also have an axobate in the shape of a cluster of lumps, and all major spines protruding as long, robust, tribladed (and panelled, in the case of C. pterophormis) appendages. C? arthuri is distinguishable from Ceratocyrtis mashae Bjørklund, 1976a in its smaller size, in Mb being situated lower in the shell cavity and in the pores being smaller; from C. stoermeri Goll & Bjørklund, 1989 and C. broeggeri Goll & Bjørklund, 1989 in its thorax and cephalis being indistinguishable externally. description. Large dicyrtid with a reduced cephalis and a long, conical thorax. The collar stricture is not marked externally. Thorax terminates on a rim that bears between 10 and 20 downwarddirected, short, conical spines. Pores on the thorax are large and polygonal. There is a size gradient from the cephalis to the thorax rim for those pores and they seem to be distributed randomly. Numerous thorns arise from bar nodes on the cephalis and the upper thorax. Spines d, V, ll and lr are of equal length and in the same plane, as a cross (see Pl. 6, fig. 8B), while Mb is reduced to a point. a and ax were not observed (maybe due to the fact that most of the specimens were observed in apical view). Spines d, V, ll and lr protrude outside the wall as horns that are similar in shape and size to the numerous thorns that the wall already bears. remarks. The possible absence of an axobate, the thorax termination and the 'cross' disposition of spines d, V, ll and lr make the assignment to genus Ceratocyrtis questionable. All these characters would fit rather well with species of the genus Lampromitra; however, the reduced size of the cephalis, and the fact that the spines protrude outside as horns do not fit with the description this genus either. The cross disposition of the main spines evokes that typical of the genus Velicucullus Riedel & Campbell, 1952; however, species of this genus (such as V. oddgurneri Bjørklund, 1976a) generally have a highly flattened shell and relatively large cephalis. early forms of Velicucullus altus Abelmann, 1990 have a more conical shell; however, the pore size, shape and density on C. ringisstola and the size of its cephalis are very unlike that of this species.
Genus Lithomelissa ehrenberg, 1847 type species. Lithomelissa microptera ehrenberg, 1854. description. Large dicyrtid with a kidney-shaped cephalic chamber and a thorax whose upper part is deformed by three, almost horizontal in some specimens, short, robust wings derived from spines d, ll and lr. These wings can be, proximally, linked to the thorax by arches (Pl. 7, fig. 10B). Spine a is free in the cephalic cavity and protrudes subapically as a tribladed horn. Arches ap are clearly marked (Pl. 8, fig. 12). The collar stricture on the dorsal side is situated at the level of apophyse a and follows arches ap. Pores vary widely in size and shape and are randomly distributed. Pores on the cephalis are smaller than on the thorax. Thorax termination is ragged. The shell is generally thin, except in some rare, late specimens (Pl. 7, fig. 11A-B).
occurrence. Sporadic from the Stylosphaera radiosa zone to the upper Cycladophora spongothorax zone (Late Oligocene to Late Miocene).
Lophophaena amictoria n. sp. lr project downwards, reach the thorax wall at its midst, continue on the wall as ribs until they become, at the thorax termination, blade-like feet. Cephalis is globular. Cephalis and thorax are distinctly separated by an inflated distally extended annular structure, delimited on top by arches aV and on the bottom by a fold that follows Mb, which somewhat resembles a scarf. Pores on the cephalis and on the collar structure are small and more or less circular while pores on the thoracic wall are larger and slightly more elliptical. They both seem to be arranged in a hexagonal pattern. Thorax termination is ragged. occurrence. Rare from the Cycladophora golli regipileus zone to the Actinomma golownini zone (early to Middle Miocene), then sporadic until the Chi zone (Pleistocene). Based on specimens reported by Lazarus & Pallant (1989) this species ranges into the early Oligocene.
remarks. This species differs from the Lophophaena macren cephala Clark & Campbell, 1945 group as illustrated in Dzinoridze et al. (1976) and Lophophaena mugaica (Grigorjeva, 1975) as illustrated in Kozlova (1999, pl. 3, fig. 16; pl. 4, fig. 3) primarily in possessing three well-developed feet. L. mugaica seems to share the same collar structure while L. macrencephala does not. Lophophaena clevei Petrushevskaya, 1971 (see Pl. 7, fig. 17 herein) also shares this structure (though slightly reduced in volume) and possesses three feet as well; however, its size and the length ratio between its cephalis and its thorax are significantly different from that of the new species.
diagnosis. Hood-shaped cephalis with triangular apical horn unconnected to spine a.
description. Dicyrtid with an ellipsoid cephalis elongated toward the apex where a short triangular, tribladed horn is present. This horn does not seem connected to any internal spine or apophyse. Indeed spine a is fused to the dorsal side of the cephalic wall and does not seem to protrude outside of it (though it is possible that it merges with the horn), nor do spines V (which joins the wall on the ventral side of the collar stricture) or d. Spines ll and lr are almost perpendicular to Mb and join the wall in an intermediate position between the dorsal and the ventral side where, in some specimens (Pl. 7, fig. 4), they can protrude as very short wings. Thorax and cephalis are separated externally by furrows along arches al and Vl: because spines ll and lr are relatively close to spine d, the furrow along al forms a smaller angle with the one along Vl thus forming a more-or-less marked dorsal shoulder. The thorax is more or less conical in outline. Pores on both segments are numerous, circular, of various sizes but generally relatively large (smaller toward the apex of the cephalis) and randomly arranged.
occurrence. Sporadic from the Eucyrtidium punctatum zone to the Chi zone (early Miocene to Pleistocene).
remarks. The apical triangular horn unconnected to spine a seems characteristic of this species. This horn evokes that of Trisulcus boldyrae Petrushevskaya, 1971; however, the thorax outline of both those species differs completely from one another. Because the collar stricture follows arches al and Vl and because of the presence of a dorsal shoulder, the general outline of the cephalis is very similar to that of more common species, such as Lophophaena thaumasia Caulet, 1991 (which differs from L. pileata in its apical and ventral tribladed horn) and Lophophaena simplex Funakawa, 1994 (which differs from L. pileata in its numerous by-spines and its thorax ridges). This cephalis outline also evokes the kidney-shaped cephalis of species Lithomelissa celsagula and L. ehrenbergi discussed above; however, not only do those species lack a dorsal shoulder but they possess a more complex neck structure based on arches ap that L. simplex, L. thaumasia and L. pileata lack.  Material. 119 specimens observed in samples from ODP sites 690, 693, 744, 747, 748, 751 and 1138. description. Large dicyrtid with a large, flattened, almost spherical cephalis and a truncated-conical to tetrahedral thorax. Both segments are separated by a clear collar stricture, above Mb. Spine a is free in the cephalic cavity and protrudes subapically as a curved, conical horn. Two other supplementary horns that are very similar in shape and size to the apical horn are also present subapically on the cephalis. They do not seem to be connected with any internal spine or apophyse. Spine V reaches the wall at the cephalic stricture but does not seem to continue outside as a horn. Spines d, ll and lr are projected downward, reach the thoracic wall at the third of its height and continue after the thorax termination as fairly long, blade-like, smooth feet. Pores on the cephalis are smaller than pores on the thorax. Both are round to elliptical. The pores on the thorax are more or less quincuncially arranged. Bars are crested on the cephalis. remarks. This species differs from species of the genus Pseudodictyophimus and from Theoperidae in the size and shape of its cephalis and the disposition of its collar stricture: in Theoperidae, the collar stricture is systematically situated at the same height as Mb, while in Pseudodictyophimus the separation between the two external segments follows furrows along arches al and Vl (Funakawa, 1995a) which is clearly not the case here. It is distinguished from Lophophaena witjazii (Petrushevskaya, 1971) in its apical horns being cylindrical instead of tribladed, its large thorax and in its three feet and from L. capito ehrenberg, 1874 in its large thorax and in lacking wings.
diagnosis. Flaring thorax with teeth at the rim; elongated cephalis; whole shell covered with thorns.
Material. 44 specimens observed in samples from ODP sites 748 and 751.
description. Dicyrtid with a spherical to apically elongated cephalis and a largely flaring truncated-conical thorax. Thorax ends on a circular rim where numerous small triangular teeth project. Spine a is fused to the dorsal side of the cephalic wall and can protrude outside the wall as a short triangular spine that can be hardly differentiated from the multitude of conical thorns projecting from the bar nodes of the cephalic wall and the upper thoracic wall. Spines d, ll and lr join the upper thoracic wall and continue as ribs. Some specimens (Pl. 7, fig. 1) exhibit a more-orless marked pore alignment following these ribs. Pores on the thorax are more or less even in size, circular to elliptical and numerous. Pores on the cephalis are slightly smaller than those on the thorax in general. The cephalic wall can be rough and crested in some specimens (Pl. 7, fig. 1).
occurrence. Found sporadically from the Cycladophora golli regipileus zone to the Acrosphaera australis zone (early to Late Miocene), rare in the Actinomma golownini zone (Middle Miocene).
Although L.? neuma differs from Petrushevskaya's (1971)  description. Large dicyrtid with a dome-shaped cephalis, bearing small rounded pores, an apical and ventral horns (usually tribladed at least at their base) and, often, numerous additional horns. The thorax is at least twice as wide and long as the cephalis. Both segments are separated by furrows along arches al and Vl. Spines d, ll and lr join the wall at the collar stricture, continue on at least half the length of the thorax, in the thoracic wall as ribs and then protrude as fairly long, downward-directed, conical to blade-like wings. Pores on the thorax are round to elliptical, relatively large (somewhat larger next to the ribs). Additional spines on the upper part of the thorax are frequent. occurrence. Sporadic from the Cycladophora antiqua zone to the Cycladophora golli regipileus zone (early Miocene), then rare until the upsilon zone (Late Pliocene).
remarks. It differs from P. tanythorax Funakawa, 1994 andP. gracilipes Bailey, 1856 in the flaring of its thorax, its size and the presence of additional horns. It differs from P. platycephalus (Haeckel, 1887) primarily in the latter having a collar stricture barely marked externally and from the specimen illustrated as Dictyophimus cf. platycephalus in Abelmann (1990) in its size and the width ratio of its cephalis and thorax; from Tripophaenoscenium laimingi Campbell & Clark, 1944 in its shorter apical horn, the thinner wall, the smaller pores and, more noticeably, in its size (the total length of T. laimingi being often more than 400 µm and its width more than 200 µm; as per Campbell & Clark (1944) and personal observations on the specimens observed in the Southern Ocean); from Clathromitra ptero phormis Haeckel, 1887 in the same characters as above, and additionally in lacking a large dendritic ax; from Spongomelissa dilli Chen, 1975 andCorythomelissa omoprominentia Funakawa, 1995a in possessing long wings/feet but lacking a rimmed peristome; from Corythomelissa horrida Petrushevskaya, 1975 andfrom C. spinosa Funakawa, 1995a in being larger, in having a wider, open thorax and in the collar stricture being distinct externally; from Corythomelissa pachyostraca Funakawa, 1995a, primarily in its weaker and shorter appendages but also in its additional spines. description. Large dicyrtid with a large bell-shaped thorax that ends on a short poreless rim with several short triangular teeth.
No visible constriction or change in contour at the collar stricture. Spine a is free in the cephalic cavity and protrudes apically as a short tribladed horn. The cephalic wall, in apical view, is separated in three sectors: one is latticed, with round to elliptical pores and thick bar nodes with thorns and the two others are one large pore each (may be covered by a velum; Pl. 6, fig. 1A) delimited by a strong, thick circular arch extending from apophyses g. Mb is reduced. Apophyses a can be seen joining a with the shell wall (Pl. 6, fig. 3B). Still in apical view, the thorax contour is irregular with a few triangular spines extending laterally from the largest part of the bell-shaped thorax: some of them could be wings extending from d, ll and ll, or even unobserved l'. Pores on the thorax are numerous, large, regularly arranged and spaced, and elliptical. Spines d, V, ll and lr seem to be all in the same horizontal plane (Pl. 6, fig. 1B) and do not seem to extend as horns or feet, but possibly wings (yet unconfirmed). No ax has been observed.
occurrence. Sporadic from the Stylosphaera radiosa to the Eucyrtidium punctatum zone (Late Oligocene to early Miocene).
remarks. The peculiar cephalic structure of this species sets it aside from the other lophophaenids or clathromitrids present in the Southern Ocean, rendering the generic assignment problematic. This structure evokes that of the specimens illustrated by Sanfilippo & Riedel (1973) as Velicucullus sp. (Sanfilippo & Riedel, 1973, pl. 20, figs 5-6;pl. 34, fig. 14) but the rest of the skeleton differs widely from our new species (specifically the shell flattening and the thorax termination). It differs from Spongomelissa adunca Riedel, 1973 andS. euparyphus Sanfilippo &Riedel, 1973 in lacking feet, in the shell flattening of these two species and in the cephalis being reduced in height; from Spongomelissa dilli Chen, 1975 and Corythomelissa omopromi nentia Funakawa, 1995a in the presence of teeth at the rim, in being taller and in its peculiar cephalic structure; from Corythomelissa horrida Petrushevskaya, 1975, C. pachyostraca Funakawa, 1995aand C. spinosa Funakawa, 1995a in lacking feet, in possessing a rim at the thorax termination and in its shorter apical horn.
Family trissocyclidae Haeckel, 1881 emend. Goll, 1968 Genus description. Bilobed cephalis with a weak sagittal constriction and a loose latticed shell wall that appears to be asymmetrical on both sides of the sagittal ring. elliptical pores are randomly distributed and of various sizes. Bars are generally wide and often crested. The lattice wall joins the sagittal ring at the apex, in the middle of its frontal side and in the upper two-thirds of the dorsal side. The shell is wider than its height.
Spine a and spine d both extend as fairly significant spines, one near the apex of the sagittal ring, the other near the antapex. Some additional spines, more modest in size, can be seen arising from some bar nodes. Spine V seems to be visible on the frontal side (see the knob-like thickening of the sagittal ring near its base (Pl. 8, figs 4A and 5A). remarks. This species differs from Eucoronis fridtjofnanseni Goll & Bjørklund, 1980, from Ceratospyris borealis Bailey, 1856 and from Lophospyris cheni Goll, 1976 primarily in its considerably wider cephalic lobes. Additionally it differs from E. fridtjofnanseni and C. borealis in its deeper sagittal constriction and in the lattice wall connecting also to the middle of the sagittal ring and not exclusively to the top and bottom of it; and from L. cheni in its lattice wall bars being wider and flatter. It also shares, to some extent, similarities with Clathrospyris sandellae Goll, 1978 but they can be distinguished in the latter lacking an apical spine, having feet and in the latticed wall joining those feet distally. It is finally distinguished from other species of the genus Ceratospyris, such as C. laventaensis Campbell & Clark, 1944, which are also found in the middle Miocene Southern Ocean, in its peculiar asymmetrical lattice wall.
diagnosis. Thorny trissocyclid with randomly distributed pores, no sagittal constriction and no sagittal-lattice pores on the dorsal side.
description. Hemispherical to spherical cephalis separated into two chambers by a sagittal ring. No sagittal constriction. ventral side of the cephalis shows several unpaired sagittal-lattice pores but dorsal side does not have any sagittal-lattice pores. The other pores on the shell wall are large, round to elliptical and more-or-less regularly arranged. Spine a extends as a short, conical apical horn. Spines d, ll and lr continue as fairly long, thin, conical feet that are bent downwards. Numerous thorns arise from bar nodes as thin, needlelike supplementary horns slightly shorter than the apical horn. occurrence. Rare, from the Stylosphaera radiosa zone to in the Cycladophora spongothorax zone (Late Oligocene to Late Miocene). Found sporadically until the Siphonosphaera vesuvius zone (Late Miocene).