Lophophaena Ehrenberg, 1847 emend. Petrushevskaya, 1971

Trubovitz, Sarah, Renaudie, Johan, Lazarus, David & Noble, Paula, 2022, Late Neogene Lophophaenidae (Nassellaria, Radiolaria) from the eastern equatorial Pacific, Zootaxa 5160 (1), pp. 1-158 : 51-52

Genus Lophophaena Ehrenberg, 1847 emend. Petrushevskaya, 1971

Type species: Lophophaena galeaorci Ehrenberg, 1854b (= Lophophaena apiculata Ehrenberg, 1874 )

Description. This genus has a relatively high cephalis, which is variable in shape but often reaches maximum width near the top. The cephalis may exhibit a distinct and elongated “neck” region, in which skeletal bars separate the main cephalic segment from the thorax, or the cephalis may be attached to the thorax near the median bar and expand upward without a clear neck. The cephalis also typically has numerous spines, which may be simple or branching. In all Lophophaena , the apical spine becomes embedded in the shell wall near the base of the cephalis, rather than being free through the length of the cephalis as it is in Lithomelissa . The embedded apical spine may protrude as a horn once it reaches the top of the cephalis, as it does in Lithomelissa . The thorax is wider than the cephalis, but it does not flare outward as widely as some other plagonid genera, such as Lampromitra , Ceratocyrtis , and Amphiplecta . Ribs and wings on the thorax are sometimes present, but rarely form strong feet as in Pseudodictyophimus .

Remarks. The original description of this genus by Ehrenberg (1847) was somewhat vague and not illustrated, leading to some of the confusion in subsequent taxonomic literature. The type species, Lophophaena galea orci Ehrenberg, 1854b (by monotypy) was first illustrated from different material by Stöhr (1880). Ehrenberg’s original flow-chart describing this genus only specified that this taxon has two segments, a wide opening on the last segment, no ribs, often is crested, and has no posterior corona of spines. Ehrenberg (1874) described several additional species in this genus, and as some of these were also illustrated a clear basis for understanding the original meaning of Lophophaena is available. Furthermore, many of Ehrenberg’s illustrated type series specimens have since been digitally re-imaged using modern light microscopy ( Ogane et al., 2009 —see citations within individual species synonymy lists below). From these descriptions and images it is clear that the original concept was quite broad, and subsequent workers have further refined the scope of the genus concept Haeckel (1862) added further specifications to this genus, noting that it has a “ring-shaped cross-constriction” [translation from the German by David Lazarus], has a flared thorax (cylindrical or bell-shaped) that is not flattened, and has one or more spines on the cephalis that can be connected to one another. In 1887, Haeckel apparently revised this description, stating that the cephalis of Lophophaena should have a group of large spines (rather than a single spine being acceptable). This revision was adopted by Campbell and Clark (1945), who described the genus as having a “cephalis armed with several large horns.” Haeckel (1887) considered Lophophaena apiculata Ehrenberg 1874 to be synonymous with Lophophaena galea Ehrenberg, 1854b , but omitted the second half of the name (orci). Petrushevskaya (1971) also included Lophophaena apiculata Ehrenberg, 1874 under Lophophaena galea orci Ehrenberg, 1854b .

Haeckel (1887) designated two subgenera within Lophophaena : Lophophaenula and Lophophaenoma . Campbell (1954) listed Lophophaenula as a junior synonym of Lophophaena . Petrushevskaya (1971) initially elevated the subgenus Lophophaenoma to the genus rank, and Lophophaena circumtexta Haeckel, 1887 was the type species of Lophophaenoma by monotypy, as well as a junior synonym of L. radians ( Ehrenberg, 1874) . While Haeckel (1887) defined the subgenus Lophophaenoma as: “Horns of the cephalis connected by anastomosing branches,” Petrushevskaya (1971) ’s genus description includes species without connected cephalic horns. She states that anastomosing branches on the cephalis are sometimes present, but particularly in more recent Lophophaenoma species, are not common. Later, Petrushevskaya (1981) considered Lophophaenoma to be a subjective synonym of Arachnocorys , presumably because the type species fit within Arachnocorys . Petrushevskaya (1981) decided that the differences between Lophophaena and Lophophaenoma , such as the variation in skeletal proportions and spine strength, were insufficient to justify separate genera, but instead of completely subsuming Lophophaenoma within Lophophaena , she suggested that some of the species would fit within Peromelissa and others in Lophophaena , but did not make any formal transfers. Subsequent usage of Lophophaena is inconsistent in the sense that some still use the narrower definition of Lophophaena and break out Lophophaenoma, sensu Petrushevskaya 1971 (i.e., Poluzzi, 1982, Matsuzaki et al., 2016), whereas others use a broader genus definition of Lophophaena (i.e., Van de Paverd, 1995). Petrushevskaya (1971) was the first to describe the internal skeletal structure of Lophophaena , which was followed and clarified by Nishimura (1990), Funakawa (1994), and O’Connor (1997). All of these authors agree that the internal skeleton of Lophophaena includes the median bar, apical spine, dorsal spine, ventral spine, right and left lateral spines, and arches connecting the apical and ventral spines to the lateral spines. The arches connecting the apical and lateral spines are incorporated into the wall of the cephalis, as is the apical horn after it passes upward from the collar structure.

Here we observed the following species of Lophophaena : Lophophaena amictoria Renaudie and Lazarus, 2015 , Lophophaena arie n. sp., Lophophaena buetschlii (Haeckel) Petrushevskaya, 1971 , Lophophaena casperi n. sp., Lophophaena cylindrica (Cleve) Petrushevskaya, 1971 , Lophophaena domovoi n. sp., Lophophaena gozui n. sp., Lophophaena hispida (Ehrenberg) Petrushevskaya, 1971 , Lophophaena ikiryo n. sp., Lophophaena ikota n. sp., Lophophaena kaonashii n. sp., Lophophaena laticeps (Jørgensen) Kurihara and Matsuoka, 2010 , Lophophaena ? leberu Renaudie and Lazarus, 2016, Lophophaena leshii n. sp., Lophophaena macrencephala Clark and Campbell, 1945 , Lophophaena nadezdae Petrushevskaya, 1971 , Lophophaena rhopalica Renaudie and Lazarus, 2016 , Lophophaena rusalkae n. sp., Lophophaena shishigae n. sp., Lophophaena simplex Funakawa, 1994 , Lophophaena undulatum ( Popofsky, 1913) n. comb., Lophophaena ushionii n. sp., Lophophaena variabilis (Popofsky) Petrushevskaya, 1971 , and Lophophaena witjazii (Petrushevskaya) n. comb.

Lophophaena circumtexta Haeckel, 1887 is not included here because it is considered to be in Arachnocorys , following Petrushevskaya (1981) ’s determination that Lophophaenoma (type species: L. circumtexta ) is a subjective synonym of Arachnocorys . Lophophaena galeata Ehrenberg, 1874 does not fit the genus description, because the apical spine of this species is free within the cephalis, making it instead a Lithomelissa . Haeckel (1887) questionably synonymized Lophophaena galeata with Lithomelissa ehrenbergi , and we agree with this genus reassignment based on the position of the apical spine, but cannot confirm the species synonymy due to the poor quality of illustrated specimens. Lophophaena ? globeacuculla Renaudie and Lazarus, 2015 has a nearly-spherical cephalis and very strong feet, which are not typical of this genus. However, it is not clear which genus would be a better fit for this species, so we do not make any formal transfer here. Lophophaena tekopua O'Connor, 1997 and Lophophaena ? thaumasia Caulet, 1991 are not included because these species both have a cephalis relatively too small and horns too strong to be typical of Lophophaena . Here we transfer these species to a new genus, Pelagomanes n. gen., which is described later in this manuscript.

Range.?Eocene–Recent.