- T. Kase (1984). Early Cretaceous Marine and Brackish-water Gastropoda from Japan. Tokyo, National Science Museum, 1-263.
- T. Kase & Y.M. Aguilar (2014). The gastropod genus Calyptraphorus (Rostellariidae: Stromboidea: Mollusca): A lazarus taxon from the Pliocene of the Philippines; Paleontological Research, 18 (3) pp. 169-175.
Calyptraphorus sp.; Tartaro Formation, mid-Pliocene; Angat area, Bulacan Province, northern Luzon, Philippines; Coll. NMNS no. PM 25619; Copyright T. Kase
Description of Calyptraphorus sp. by Kase & Aguilar, 2014:
- "Shell fusiform, completely covered with thin glazed callus, consisting of ca. 13 whorls including protoconch. Protoconch naticiform, smooth, but details of coiling pattern and sculpture unknown. Teleoconch comprising ca. 10 weakly convex whorls separated by a very weakly impressed suture. Surface sculpture of whorls obscurely observable under callus cover, consisting of orthocline axial ribs and numerous fine spiral cords; number of axial ribs uncountable, but four ribs observed beneath callus on one-fourth of eighth whorl; axial ribs becoming obsolete on penultimate whorl, absent from last whorl. Blunt varices seemingly present at irregular intervals on some whorls, recognized as a swelling of callus. Last whorl occupying more than half of total shell length, strongly tapered anteriorly, incomplete, seemingly with a short, narrow anterior canal. Outer lip totally missing. Posterior canal extending posteriorly up to base of seventh whorl, then U-turned, extending anteriorly to posterior part of last whorl."
Locus typicus: AGT 2 (14°57.114'N, 121°02.999'E), riverbed of the Bayabas River in the Barangay (village) of Banaban,
Angat Municipality, Bulacan Province, the Philippines.
Stratum typicum: lower part of the Tartaro Formation, Pliocene