Amphiplecta sp.

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 : 15

Amphiplecta sp. cf. A. kikimorae

Plate 2, Figs. 6A – 7B .

Amphiplecta acrostoma?, Renz, 1974 , pl. 18, fig. 12.

Unknown plagonid group C sp 73, Trubovitz et al., 2020, supplementary data 7.

Remarks. This species resembles Amphiplecta kikimorae n. sp. (Pl. 2, Figs. 1A – 5B ) except that it has significantly larger pores, is overall larger in size, has a more widely flared thorax, and a less pronounced apical horn. However, it does have a cephalis of similar shape, and the same prominent AL and AD arches. It differs from Amphiplecta acrostoma Haeckel (Pl. 1, Figs. 1A – 2 ) and A. cylindrocephala Dumitrica in that the cephalis is closed at the top. A specimen similar to ours was figured by Renz (1974) and identified as Amphiplecta acrostoma ?, but the poor image quality makes it difficult to discern the pore size of Renz’s specimen, and say with certainty it is conspecific with ours. However, we believe Amphiplecta sp. cf. A. kikimorae does not match any Amphiplecta species so far described, and could be justified as a new species after more specimens can be documented.

Material Examined. 2 specimens from samples 321-1337A-7H- 6, 104–107cm (Early Pliocene) and 321- 1337D-1H-1, 0–3cm (Recent).

Range. Early Pliocene—Recent in the EEP ( Table 1 ). The specimen figured by Renz (1974) was listed as Quaternary in age.

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 2. Relative abundance of specimens and taxa belonging to Plagiacanthoidea and Lophophaenidae per sample, from IODP Site U1337 in the EEP over the last ~10 Ma. The relative percentages of total taxa are represented by the blue lines and the red lines represent the percentages of total specimens (triangles = Plagiacanthoidea; circles = Lophophaenidae). The Plagiacanthoidea was among the most abundant and speciose of radiolarian groups encountered in Trubovitz et al. (2020), with at least 10% of the specimens and 20% of the taxonomic richness in every sample. Within the Plagiacanthoidea, lophophaenids consistently made up the majority of specimens (~67%) and taxa (~61%). Data are from Trubovitz et al. (2020).

FIGURE 5. Internal skeletal structure of Amphiplecta acrostoma Haeckel, 1887.

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

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