Conus
(Plagioconus) sp. (Psarras & Koskeridou & Merle,2021)
Shell description
Medium-large-sized shells (SL max.: 76.1
mm). Spire whorls medium to high, with conical outline. Protoconch multispiral.
Early spire whorls conical, slightly elevated and beaded, with angulated
shoulder. Late spire whorls conical, flat to striated, with straight to convex
sutural ramp. Suture incised, of variable depth. Subsutural flexure moderately
deep to deep, moderately curved, strongly asymmetrical. Sutural ramp straight
to slightly inflated and convex. Shoulder smooth to subangulated. Spiral
angulation at shoulder, as separation of last whorl and sutural ramp. Aperture
straight, narrow. Last whorl elongated, conical. Fasciole smooth, elongated,
slightly twisted. Faint spiral cords at anterior part of last whorl.
Description of colour pattern
The first pattern level consists of an
alteration of fluorescent spiral bands, on a non-fluorescent base
colour, with one thin fluorescent band at the position of the maximum diameter,
another wide fluorescent band near the shoulder of the shell, and, in some
shells, a third smaller band present on half of the anterior part of the last
whorl (Fig. 30B). The second level consists of rows of dots and dashes,
which are axially or spirally arranged on the surface of the shell, on top
of the first field. The colour pattern of the spire whorls consists of
fluorescent flammulae of irregular width, usually continuing on the last whorl,
as axial dots or dashes (Fig. 30G). The pattern is not consistent in all
shells, as some shells under the UV light display either faded patterns (Fig.
30C), one pattern on the last whorl (Fig. 30B), or none at all (Fig. 30D).
Remarks
The Cretan specimens are mostly broken, but the
remaining shell surfaces are in pristine condition, the beads on the spire
whorls are visible and, most importantly, the colour patterns can be
distinguished under UV light. The specimens of Conus (Plagioconus)
sp. display variable shoulder angulation height of the spire (Fig. 30; Table
14). The colour pattern is consistent, with fluorescent bands and occasional
spiral or axial dots and dashes. Some of the studied specimens have previously
been identified by Symeonidis & Kostantinidis (1968) as Conus puschi,
here regarded as a synonym Conus (Plagioconus) elatus Michelotti,
1847. After studying the material, we noticed that the overall spire outline
of Conus (Plagioconus) sp. is more straight-sided, than Conus (Plagioconus)
elatus Michelotti, 1847, which has a slightly inflated outline on the
middle whorls. The spire of Conus (Plagioconus) elatus then
continues to much more pronounced later spire whorls, which is not the case for
Conus (Plagioconus) sp. Also, the shells of Conus (Plagioconus)
elatus have almost no colour pattern (only flammulae and some blotches
on the spire whorl), while the specimens of Conus (Plagioconus)
sp. are much more flamboyant.
Hall (1966) illustrated specimens of several varieties
of other species and considered them as synonyms of Conus aquensis d’Orbigny,
1852. These specimens are a type specimen of Conus oboesus? var. paucisuturata
Sacco, 1893, a type specimen of Conus oboesus? var. elatoides
Sacco, 1893, a type of Conus puschi var. pseudobiconica
Sacco, 1893, a type specimen of Conus pushi var. peracutolonga
Sacco, 1893 and a type specimen of Conus elatus var. fusuloparva
Sacco, 1893. These specimens have the same conical, elongated spire whorls
and angulation at the shoulder as Conus (Plagioconus) sp.
As we had no access to their colour
patterns, we cannot check the synonymy of Hall (1966). A comparison with the
syntype (MNHN.F.A13061) of Conus (Plagioconus) aquensis (Fig.
32) from the early Miocene of the Aquitaine Basin shows that Hall’s specimens
possess more angulated shoulders, high conical spires and relatively narrower
diameters (RD). Two specimens named as Conus puschi from Davoli
(1972: pl. 8 figs 17a–b, 19) have an elongated spire similar to that of the
studied specimens (Fig. 30B1– C2), but the spire whorls are not distinctly
elevated and there is a slight angulation at the shoulder. We also wait for
their colour pattern descriptions in order to compare to the Cretan specimens.
Stratigraphic range
Tortonian of Greece (Messara Basin and Sitia Basin,
Crete (Symeonidis & Kostantinidis 1968; this work)).
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Fig. 30. Conus (Plagioconus) sp. from the Tortonian of Crete (Greece) in apertural,
abapertural and apical views under natural (A1, B1, B3, C1, D1, E1, F, G1) and UV
light. A.
Specimen AMPG(IV) 3901, Psalidha. B.
Specimen
AMPG(IV) 3890, Filippi. C. Specimen
MNHN.F.A83095, Panassos. D. Specimen
AMPG(IV) 3881, Achladhia. E.
Specimen AMPG(IV) 3903, Psalidha. F.
Specimen AMPG(IV) 3904, Psalidha. G. Specimen
AMPG(IV) 3902, Psalidha. |
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Conus (Plagioconus) sp. mm. 61 x 21 Rethymno a 800 m. s.l.m. –
Creta [AZFC
5643-01] |
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Conus oboesus? var. paucisuturata (3) (Sacco, 1893) Tav. V fig. 33 |
Conus oboesus? var. paucisuturata (2) (Sacco, 1893) Plate 22 fig. 2 N. 66 Coll. Sacco Middle Miocene – Torino mm. 50,6 x
21,4 |
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Conus
oboesus? var. elatoides (3) (Sacco, 1893) Tav. V fig. 35 |
Conus
oboesus? var. elatoides (2) (Sacco, 1893) Plate 22 fig. 8 N. 67 Coll. Sacco Middle Miocene – Torino mm. 45,6 x 19,2 |
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Conus puschi var. pseudobiconica (3) (Sacco, 1893) Tav. V fig. 43 |
Conus puschi var.
pseudobiconica (2) (Sacco, 1893) N. 71 Coll. Sacco Plate 22 fig. 13, 23 Middle Miocene – Torino mm. 51,5 x 20,8 |
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Conus puschi var. peracutolonga (3) (Sacco, 1893) Tav. V fig. 46 |
Conus puschi var.
peracutolonga (2) (Sacco, 1893) N. 73 Coll. Sacco Plate 22 fig. 18 Middle Miocene – Torino mm. 55,9 x 20,8 |
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Conus elatus var. fusuloparva (3) (Sacco, 1893) Tav. IV fig. 23 |
Conus elatus var.
fusuloparva (2) (Sacco, 1893) Coll. Sacco Plate 22 fig. 19 Tortoniano – S. Agata mm. 48,8 x 14,9 |
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Plagioconus sp. B Specimen AMPG(IV) 3890, Filippi. mm. 67,5 |
Conus (Plagioconus) sp. mm. 61 x 21 Rethymno a 800 m. s.l.m. –
Creta [AZFC
5643-01] |
Plagioconus sp. C Specimen MNHN.F.A83095, Panassos. mm. 50 |
Plagioconus sp. A Specimen AMPG(IV) 3901, Psalidha mm. 48,8 |
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Bibliografia Consultata
·
(2) - Hall C.A. Jr. 1966. Middle Miocene Conus (Class Gastropoda) from Piedmont, Northern
Italy. Bollettino della Società Paleontologica Italiana 3 (2):
111–171