On some Vetigastropoda (Mollusca, Gastropoda) from the Plio-Pleistocene of the Philippines with descriptions of three new species
Author
Helwerda, Renate Ariane
Author
Wesselingh, Frank Pieter
Author
Williams, Suzanne T.
text
Zootaxa
2014
3755
2
101
135
journal article
46615
10.11646/zootaxa.3755.2.1
e02bbd39-b7ee-4ddf-8109-3407dd6d2ea2
1175-5326
250959
1872ECAB-3C5C-4D76-93A0-A8626F75B96E
Thelyssina
?
spec. 1
(
Figures 20–22
)
Material.
Anda 2 (5); AndaDeVos (2).
Characterization.
Shell minute, H
0.8 mm
,
W
0.7
mm; P 1.1 whorls, with fine anastomosing sculpture, DN
0.08 mm
; P/T boundary rounded varix; second varix at 1.6 whorls; T whorls with a sharp keel; microsculpture granulate; body whorl with two sharp spiral ribs; aperture rounded; umbilicus narrow; umbilical ridge weak.
Remarks.
This seguenzioid skeneimorph species is provisionally placed in
Thelyssina
, based on the presence of dendritic teleoconch sculpture and a keeled shoulder. At the highest magnifications available, we observed very brilliantly shiny shell material at the inner side of the outer lip that we interpret as nacre. The small protoconch is also similar to the protoconch of the
type
species for the genus,
T. sterrha
Marshall
, 1983
, in the anastomosing sculpture and characteristic shape. However, this assignment is uncertain, because the fossil species is relatively tall and more strongly granulate and keeled.
Thelyssina
?
spec. 1 also resembles
Conotalopia minima
(
Golikov, 1967
)
, a Recent trochid species from
Japan
, in general shape, but it has a smaller protoconch relative to the first teleoconch whorl, a dendritic granulate sculpture on the teleoconch and a narrower umbilicus.