Margarites hayashii, Kiel & Aguilar & Kase, 2020

Kiel, Steffen, Aguilar, Yolanda M. & Kase, Tomoki, 2020, Mollusks from Pliocene and Pleistocene seep deposits in Leyte, Philippines, Acta Palaeontologica Polonica 65 (3), pp. 589-627 : 617-618

Margarites hayashii sp. nov.

Fig. 30 .

Zoobank LSID: urn:lsid:zoobank.org:act:24D9CA99-1B02-434F-B900-EFECAF6D8BFC

Etymology: For Hiroki Hayashi (Shimane University, Japan) who provided preliminary results of planktonic foraminifer analyses for biostratigraphy.

Type material: Holotype: NMNS PM 28444 . Paratypes: NMNS PM 28445 , 28446 from the type locality; all specimens with defoliated shells .

Type locality: Liog-Liog Point , Leyte, Philippines .

Type horizon: Lower Pliocene part of the Bata Formation .

Material.— Six specimens from the Pliocene of Liog-Liog

Point: the type material and NMNS PM 28451 (three individuals) .

Dimensions (in mm).—NMNS PM 28444, W = 17.0, H = 16.0; NMNS PM 28445, W = 12.5, H = 8.0 (specimen with most complete spire); NMNS PM 28446, W = 12.0.

Diagnosis.—Trochiform Margarites with weakly convex whorls, sculptured by six spiral cords and a finer spiral between cords; umbilicus narrow, base with fine spiral lines.

Description.—Shell trochiform, at least five whorls with convex profile, sculpture of up to six low, widely spaced cords crossed by strongly prosocline growth lines, some interspaces with fine cord; basal margin marked by another cord; base sculptured by finer and more densely spaced spiral lines than whorl flanks; umbilicus conical, width about 1/3 of shell diameter; aperture circular, strongly inclined.

Remarks.—Two similar species are Margarites shinkai Okutani, Tsuchida, and Fujikura, 1992 living around seep sites in Sagami Bay, Japan ( Okutani et al. 1992; Sasaki et al. 2010) and M. similis Zhang and Zhang, 2017 from the Okinawa Trough ( Zhang and Zhang 2017). The former differs from Margarites hayashii by having a more angular whorl profile, more numerous spiral cords on the whorls and narrower umbilicus. M. similis has a lower spire and more conical base than Margarites hayashii , and more densely spaced spiral cords.

Stratigraphic and geographic range.—Late Pliocene, Leyte, Philippines.

Figures

Fig. 30. The trochoid gastropod Margarites hayashii sp. nov. from the late Pliocene Liog-Liog Point seep deposit in Leyte, Philippines. A. Holotype NMNS PM 28444, in apertural (A1), apical (A2), and basal (A3) views. B. Paratype NMNS PM 28445 in apical view. C. Paratype NMNS PM 28446, in apical (C1) and basal (C2) views.