Lophophaena shishigae, n. sp.

Lophophaena shishigae n. sp.

Plate 35, Figs. 1–6B.

urn:lsid:zoobank.org:act: A289D1AC-8B84-406E-B5E7-C6CF4358263F

unknown plagonid group C sp 17 (partim.), Trubovitz et al., 2020, supplementary data 7.

Diagnosis. Lophophaena with a small, balloon-shaped cephalis that has numerous conical spines, and a flared conical thorax that has multiple strong ribs.

Description. The cephalis of this species is narrow at its base and reaches its widest point about ⅔ of the way up, giving it a balloon-like shape. There are many conical spines protruding from the cephalis, one of which is the apical spine, though it is not differentiated from the others. The small pores on the cephalis are about the same size, shape, and density as those on the thorax. The thorax extends down from the neck constriction in a roughly conical shape, flaring outward to varying degrees among specimens. The thorax has multiple strong ribs, and may become hyaline toward the base in some individuals (i.e., fig. 2).

Remarks. This species is similar to Lophophaena variabilis (Pl. 22, Figs. 9A –11C), except that the cephalis is always heavily-silicified, rounded, and closed at the top. It reaches its widest point about 2/3 up from the base of the cephalis. On the thorax, the numerous spines have a tendency to form long ribs, rather than protruding through the thorax wall as they commonly do in L. variabilis. It differs from L. casperi (Pl. 28, Figs. 1A–9B) in that the cephalis is relatively narrower, particularly at its widest point, and the thorax flares outward in a roughly conical shape, rather than expressing sharp shoulders before tapering inward toward the base. The more widely flared thorax, strong ribs, and more balloon-shaped cephalis also distinguish this species from L. rusalkae n. sp. (Pl. 29, Figs. 1A – 6). This species differs from Arachnocorys jorogumoae n. sp. (Pl. 4, Figs. 1A –11) in that it is consistently much smaller in size, has relatively smaller pores, and does not have dendritic spines on the cephalis.

Material examined. 14 specimens observed from Late Miocene samples 321-1337D-23H- 6, 134–137cm and 321-1337A-21H-1, 33–35cm.

Holotype. Pl. 35, Fig. 1; sample 321-1337D-23H- 6, 134– 137cm; ECO-146; W4-2.

Paratypes. (1) Pl. 35, figs. 2A–B; sample 321-1337D-23H- 6, 134–137cm; ECO-146; W37-1. (2) Pl. 35, fig. 3; sample 321-1337A-21H-1, 33–35cm; ECO-144; V 2-2. (3) Pl. 35, fig. 4; sample 321-1337D-23H- 6, 134–137cm; ECO-147; W30-4. (4) Pl. 35, fig. 5; sample 321-1337D-23H- 6, 134–137cm; ECO-146; Y6-1. (5) Pl. 35, figs. 6A–B; sample 321-1337D-23H- 6, 134–137cm; ECO-146; A34-4.

Measurements. Cephalis height 33–41 (37)μm; cephalis width 25–30 (27)μm; width at neck 19–25 (23)μm; width at shoulders 39–68 (51)μm. Based on 8 specimens.

Etymology. Named for Shishiga, the troublesome female swamp creature in Russian mythology.

Range. Late Miocene in the EEP, range not well constrained (Table 1).