Lophophaena ushionii, Trubovitz, Sarah, Renaudie, Johan, Lazarus, David & Noble, Paula, 2022

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 : 67

Lophophaena ushionii n. sp.

Plate 31, Figs. 7A –11B.

urn:lsid:zoobank.org:act:563EAE81-E06C-40F6-B180-33517AB17AB3

unknown plagonid group C sp 32 cf, partim., Trubovitz et al., 2020, supplementary data 7.

Diagnosis. Lophophaena with a large cephalis that has two prominent bladed horns on the dorsal and ventral sides, and a third, often smaller horn that forms between them on the apex of the cephalis.

Description. This species has a large cephalis that is distinct for its two strong bladed horns that protrude from the widest part of the cephalis at approximately 45-degree angles. The horn on the dorsal side is an extension of the apical spine, and the other is not related to any of the primary spines, but sits just above the short and thin ventral spine. In one specimen we observed, the horn extending from the apical spine was strongly forked (fig. 11), but since few specimens were documented it is not clear how common this is. The thorax is approximately 1.5x as wide as the cephalis, and has extensions of the dorsal and lateral spines that form short appendages. Pores on the thorax are slightly larger than those on the cephalis.

Remarks. This species resembles Lophophaena gozui n. sp. (Pl. 31, Figs. 1A – 6 ) except that the cephalis is much larger, has three horns rather than two, and the thorax is relatively more narrow compared to the width of the cephalis ( Figure 13 ). In L. gozui , the average ratio of thorax:cephalis width is 2.52; for L. ushionii , this ratio averages 1.46. A chart showing the differences in cephalis dimensions is included above in the description of L. gozui . Another difference between these two species is that L. ushionii has short appendages on the thorax front he dorsal and lateral spines, whereas in L. gozui these primary spines join the wall of the thorax.

Material examined. 10 specimens observed from samples 321-1337A-31X-6W, 4–6cm (Middle Miocene) and 321-1337D-26H-3W, 142–144cm (Late Miocene).

Holotype. Pl. 31, Figs. 7A–B ; sample 321-1337A-31X-6, 4–6cm; ECO-151; T6-1 .

Paratypes. (1) Pl. 31, fig. 10; sample 321-1337A-31X-6, 4–6cm; ECO-151; O40-3. (2) [not figured] sample 321-1337A-31X-6, 4–6cm; ECO-151; U26-4.

Measurements. Cephalis height 49–60 (54)μm; cephalis width 40–52 (46)μm; thorax width 50–75 (65)μm; ratio of thorax:cephalis width 1.3–1.6 (1.5). Based on 9 specimens. Note: thorax width should be considered the minimum width, as the thorax is typically not fully preserved.

Etymology. Named for the Japanese yokai, ushi oni, which comes from the sea and has the head of an ox.

Range. Middle—Late Miocene, lower boundary not determined ( Table 1 ).

Figures

FIGURE 1. Diagram illustrating the general skeletal morphology of Lophophaenidae, and terminology used in this manuscript. Dashed lines indicate spines that are not visible from the angle shown, as they extend into the skeleton. An example specimen of Lophophaena casperi n. sp. is included for comparison to the diagrams.

FIGURE 6. Internal skeletal structure of Arachnocorallium calvata (Haeckel, 1887) Petrushevskaya, 1971.

FIGURE 7. Internal skeletal structure of Arachnocorys umbellifera (Haeckel, 1862) Petrushevskaya, 1971.

FIGURE 13. Chart illustrating the differences between Lophophaena gozui n. sp. (orange diamonds) and L. ushionii n. sp. (green squares), in terms of cephalis height and the ratio between thorax and cephalis width. L. gozui has a shorter average cephalis height (40 microns) compared to L. ushionii (average cephalis height = 54 microns). In addition, the thorax is proportionally wider compared to the cephalis in L. gozui (average ratio of thorax:cephalis width = 2.5). L. ushionii has a proportionally narrower thorax (average ratio of thorax: cephalis width = 1.5).