Conus
sieboldianus (Makiyama, 1927)
Description.
Shell
rathey small, straight, elongate-biconic, very broadly and angularly
shouldered, not very thick. Spire conoidal, scalar, about one-third the height
of the aperture, outline straight. Whorls about 8, regularly increasing,
concave; the angle of the shoulder close to the lower suture forming a
supra-sutural ridgre; the surface below the angle vertical, less than a sixth
of the height of a whorl; the last large, attenuated below. Suture impressed, irregularly
undulating, slightly appressed. Sculpture: the angle granulate on the early 3
post-embryonal whorls; the concave slope of the shoulder with numerous
hair-like curved radial threads, nothing but enforced incremental lines,
crossed by very obscure unequal spiral lines; then body-whorl with about 4
shallow grooves around the periphery just below the angle, and many spiral
grooves on the anterior portion, increasing the widths anteriorly; curve of
incremental lines concave above the angle and slightly arched forward below.
Aperture straight and narrow, with parallel lips. Height, 28mm.; diameter,
14mm. Type: Cotype, no 401 (2).
This species is very
closely allied to C. sieboldii Reeve (Conch, Icon., sp. 269.), a species
living in the temperate waters of Japan, from which it differs in that the
shell is much smaller, the spire is straight and not so sharply acuminate, the
supra-sutural ridges is not so elevated, the suture is appressed, and that
there is shallow but distinct peripheral grooves on the body-whorl. Some of C.
sieboldii are less elongate and approach the present species. But the spire
of the living species is always acuminate and its outline is markeldly concave.
I have not examined the specimens of C. rarimaculatus (Sowerby, 1870) a
living species of the China Sea, which is said to be the young of C.
sieboldii: judging from the figure
(Proc. Zool:Soc., 1870, pl. 22, f.4), that species has no peripheral
grooves of C. sieboldianus (2).
This species appears to be
identical with the species described by Makiyama. It is characterized by the 2
to 4 spiral lines immediately below the shoulder and very weak spirals on the
subsutural slope. Conus oinouyei
Yokoyama ( 1928, pl . 1 , fig. 16 ) from the Lower Byoritzu beds of Formosa is
very closely related, but has a slightly lower spire. Although Yokoyama did not
mention the spirals below the shoulder, they are clearly visible on his figure.
Whether or not the specimens Nomura referred to C. odengensis Martin are
actually that species I am not prepared to say, but it seems quite certain that
his placing of C.
oinouyei in the synonymy of C. odengensis is incorrect (1).
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Conus sieboldianus
Holotype JC200401 |
Conus sieboldianus (2) Plate IV figs. 16,17 Lower Pliocene |
Conus (Leptoconus) sieboldianus Makiyama, Gaj Formation, Ranjitpur
Member, Early Miocene, 2.5 km ESE of Ranjitpur (India). Fig. 3; Sp. No. 38/311, apertural view. Fig.4; Sp. No.
38/979, apertural view. Fig. 5; Sp. No. 38/315, back view. |
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Conus sieboldianus (1)
Plate 6,
figures 10, 15-16
10,16. ( USNM 562775) mm. 26 x 13 Yonabaru clay ( 17451 ) 15. ( USNM 562776). Apertural view ( X2) height 23.5 mm, diameter 11 mm. Yonabaru clay ( 17447) |
Pl. XXII fig. 4 |
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Conus sieboldii mm. 90 |
Conus sieboldianus (1)
Plate 6,
figures 10
USNM 562775 mm. 26 x 13 |
Bibliografia
·
(2)
- Makiyama, 1927. Memoirs of the College of Science Kyoto Imperial
University, ser. B, 3 (1 ): 1 -145
- (3) - Jain (2014) "Neogene
Fossils From Kathiawar, Gujarat, India With Special Emphasis on Taxonomic
Description of Molluscs and Corals" (Courtesy of Jain on 20/11/2023)