Lithomelissa babai, 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 : 42-43

Lithomelissa babai n. sp.

Plate 18, Figs. 1A – 5B .

urn:lsid:zoobank.org:act:2B2D2DC5-3F5E-4BB8-B39A-795A513F78A2

unknown plagonid group C sp 27, Trubovitz et al., 2020, supplementary data 7.

Diagnosis. Lithomelissa with a hemispherical cephalis exhibiting multiple long conical spines, and a cylindrical thorax that is slightly wider than the cephalis.

Description. The cephalis of this species is hemispherical in shape, and is very strongly silicified with large, framed pores. This species has several long, conical spines on the cephalis. These are easily broken off, but often at least two are preserved and our specimens showed up to six spines. One of the cephalic horns is connected to the apical spine, which is free within the cephalis like all Lithomelissa species. This apical horn is most often thin and conical like the others, but it can apparently develop into a stronger, tri-bladed horn in some individuals. The thorax is cylindrical in shape and is always wider than the cephalis. There are enlarged pores at the top of the thorax, near the connection to the cephalis. The dorsal and lateral spines protrude slightly through the wall of the thorax, but do not form long appendages.

Remarks. This species differs from Lithomelissa dybbuki n. sp. (Pl. 19, Figs. 1–7 ) in that it is larger overall, and has more spines on the cephalis. The collar structure is sunken into the thorax, so the species does not have a constriction at the base of the cephalis, differentiating it from Lithomelissa mitra (Pl. 15, Figs. 4A – 6 ), L. celsagula (Pl. 15, Figs. 1A – 2B ), L. alkonost n. sp. (Pl. 16, Figs. 1A – 7B ), and L. sirin n. sp. (Pl. 17, Figs. 1 –11B).

Material examined. 42 specimens observed from samples 321-1337A-10H-2, 91–94cm (Early Pliocene), 321-1337A-7H- 6, 104–107cm (Early Pliocene), 321-1337A-6H-3, 29–32cm (Late Pliocene), 321-1337A-5H-5, 11–14cm (Late Pliocene), 321-1337A-4H-2, 16–19cm (Middle Pleistocene), 321-1337A-3H- 2, 103–106cm (Middle Pleistocene), and 321-1337D-1H-1, 0–3cm (Recent).

Holotype. Pl. 18, Figs. 1A–C; sample 321-1337A-7H-6 , 104– 107cm; ECO-143; C26-3.

Paratypes. (1) Pl. 18, fig. 2; sample 321-1337A-7H- 6, 104–107cm; ECO-143; U30-1. (2) Pl. 18, figs. 3A–B; sample 321-1337A-7H- 6, 104–107cm; ECO-133; G15-3. (3) Pl. 18, figs. 4A–B; sample 321-1337A-7H- 6, 104– 107cm; ECO-133; X24-4. (4) Pl. 18, figs. 5A–B; sample 321-1337A-7H- 6, 104–107cm; ECO-134; K38-2. (5) [not figured] sample 321-1337A-7H- 6, 104–107cm; ECO-135; F37-4. (6) [not figured] sample 321-1337A-7H- 6, 104–107cm; ECO-134; G27-1.

Measurements. Height of cephalis 36–43 (39)μm; width of cephalis 32–41 (36)μm; width of thorax at shoulder area 46–59 (51)μm.

Etymology. Named for the boogeyman in Russian folklore, Babai.

Range. Early Pliocene–Recent, EEP ( 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 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 3. Locality map of IODP Site U1337, where all samples for this study were collected. Map from Google EarthTM.

FIGURE 4. Examples of specimen measurements discussed in the Systematic Paleontology section of this study.

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.