Dulcina liogliogensis, 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 : 595-596

Dulcina liogliogensis sp. nov.

Fig. 7 .

Zoobank LSID: urn:lsid:zoobank.org:act:4637E9DC-6DE5-43B0-A3D0-4AFC72FAEEC2

Etymology: In reference to the type locality at Liog-Liog Point.

Type material: Holotype NMP-2161, an articulated specimen; paratypes: NMNS PM 28127 (articulated), NMNS PM 28130 (left valve), NMNS PM 28131 (internal mold), NMNS PM 28136 (articulated), 28165 (internal mold).

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

Type horizon: Upper Pliocene part of the Bata Formation .

Material.— Late Pliocene of Liog-Liog Point : type material and many specimens including ( NMNS PM 28127– 28130 , 28135–28137 ) ; early Pleistocene of Buhoc Point : two specimens ( NMNS PM 28131 , 28165 ) ; early Pleistocene of Amtipolo Point : four specimens ( NMNS PM 28138–28141 ) .

Dimensions (in mm). — NMP-2161, L = 69.5, H = 61.2; NMNS PM 28127, L = 64.4, H = 58.5; NMNS PM 28130, L = 63.7, H = 56.1; NMNS PM 28131, L = 64.3, H = 56.4; NMNS PM 28136, L = 65.6, H = 61.4; NMNS PM 28165, L = 52.0, H = 49.1.

Diagnosis.—Large, little inflated Dulcina with broad posterior margin; growth lines irregular, indistinct; hinge plate narrow with remnant of cardinal tooth in left valve.

Description.—Large, rather flat shells with oval outline, W/L ratio c. 0.38; umbones small, prosogyrate, elevated, positioned anteriorly at about 40% of total shell length; anterior margin broad, well-rounded; posterior side tapering on both dorsal and ventral sides, posterior margin truncate; escutcheon lanceolate; lunule small, elongate; anterodorsal area narrow, marked by distinct incision; posterodorsal area narrow, marked by shallow sulcus; external sculpture of irregular commarginal growth increments. Shell interior with faint radial striations; anterior adductor muscle scar elongate, reaching below horizontal midline of shell to ~60% total shell height, detached from pallial line for 3/5 its length; posterior adductor muscle scar pear-shaped, broad groove running from umbo to its anterior margin; hinge plate narrow, left valve with remnant of short cardinal 4b; length of ligament nymph ~70% of length of posterodorsal margin.

Remarks.— Dulcina liogliogensis sp. nov. is somewhat similar to D. guidoi but with broader posterior margin (not as acutely rounded as in guidoi ); furthermore, Dulcina guidoi reaches 42 mm, whereas Dulcina liogliogensis reaches 60 mm, and the umbones of D. liogliogensis are in a more central position compared to D. guidoi , where they are displaced toward the anterior.

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

Figures

Fig. 7. The lucinid bivalve Dulcina liogliogensis sp. nov. from Pliocene (A–D, F, Liog-Liog Point) and Pleistocene (E, Buhoc Point) seep deposits in Leyte, Philippines. A. Holotype NMP-2161, articulated specimen; view on outer shell surface of right (A1) and left (A2) valves, dorsal view (A3). B. Paratype NMNS PM 28127, articulated specimen; view on outer shell surface of left valve (B1), dorsal view (B2). C. Paratype NMNS PM 28130, disarticulated left valve, close-up on hinge. D. Paratype NMNS PM 28165, internal mold, view on left valve showing anterior adductor muscle scar. E. NMNS PM 28131, internal mold of articulated specimen, view on left valve. F. NMNS PM 28136, articulated specimen, view on anterior external surface.