Lophophaena ikiryo, n. sp.

Lophophaena ikiryo n. sp.

Plate 32, Figs. 1A – 8.

urn:lsid:zoobank.org:act: 80B504BF-6D68-448F-869B-E6BE8D8E82FB

Lithomelissa thoracites Haeckel, Boltovskoy and Riedel, 1987, pl. 4, fig. 7

unknown plagonid group C sp 8, partim., Trubovitz et al., 2020, supplementary data 7.

unknown plagonid group C sp 54, Trubovitz et al., 2020, supplementary data 7.

Diagnosis. Lophophaena with a large, sub-rectangular cephalis that tends to be increasingly hyaline towards the top and has a thorax with long, conical appendages extending from the dorsal and lateral spines.

Description. This species has a relatively large cephalis that is somewhat rectangular in shape, with slightly flattened sides. Pore size decreases from the neck to the apex of the cephalis, and in many cases the top ⅓ of the cephalis can be hyaline. The apical spine is subdued, barely extending from the top of the dorsal side of the cephalis. However, it forms a strong indentation where it runs along the wall of the cephalis, and appears to be pinched inwards. The largest pores on the skeleton occur around the neck area. The thorax is slightly more broad than the cephalis, and exhibits strong appendages extending from the dorsal and lateral spines. These spines are conical, and tend to be significantly thicker than the apical spine.

Remarks. This species differs from Peromelissa thoracites (Pl. 38, Figs. 7A – 10) in that it is much larger, and the top of the cephalis tends to be hyaline or nearly so. It also has a consistently poorly developed apical horn, whereas Peromelissa thoracites usually has an apical horn of approximately the same strength as the dorsal and lateral spines on the thorax. The ranges of these two species overlap slightly, but L. ikiryo was restricted to the Late Miocene—Early Pliocene, whereas P. thoracites was present from the Latest Miocene—Recent, reaching greatest abundances in the Pleistocene.

Material examined. 50 specimens observed from samples 321-1337A-16H- 6, 121–124cm (Late Miocene), 321-1337A-14H-7, 39–42cm (Late Miocene), 321-1337A-12H-5, 23–26cm (Late Miocene), and 321-1337A-10H-2, 91–94cm (Early Pliocene).

Holotype. Pl. 32, figs. 4A–B; sample 321-1337A-14H-7, 39–42cm; ECO-138; E37-1.

Paratypes. (1) Pl. 32, fig. 9; sample 321-1337A-12H-5, 23–26cm; ECO-137; C3-3. (2) Pl. 32, figs. 1A–B; sample 321-1337A-14H-7, 39–42cm; ECO-140; L33-4. (3) Pl. 32, figs. 3A–B; sample 321-1337A-16H- 6, 121–124cm; ECO-142; K4-2. (4) Pl. 32, figs. 6A–B; sample 321-1337A-16H- 6, 121–124cm; ECO-143; SS7-1. (5) Pl. 32, fig. 8; sample 321-1337A-16H- 6, 121–124cm; ECO-143; R 47-2. (6) Pl. 32, figs. 5A–B; sample 321-1337A-16H- 6, 121–124cm; ECO-143; F33-1. (7) Pl. 32, figs. 7A–B; sample 321-1337A-14H-7, 39–42cm; ECO-138; J41-1.

Measurements. Cephalis height 51–59 (55)μm; cephalis width 41–49 (44)μm; neck width 32–40 (37)μm; width at shoulders 48–62 (52)μm. Based on 13 specimens.

Etymology. Named for the ghostly spirits of living people that temporarily leave their bodies in Japanese folklore, Ikiryô.

Range. Late Miocene—Pliocene in the EEP (Table 1).