Plagioconus

Harzhauser, Mathias & Landau, Bernard, 2016, A revision of the Neogene Conidae and Conorbidae (Gastropoda) of the Paratethys Sea, Zootaxa 4210 (1), pp. 1-178 : 137-139

Plagioconus marii (Sacco, 1893)

Figs 30 I, 32F1–F3, 32G1–G3

[ Conus ] Chelyconus Marii Sacc. — Sacco 1893b: 62, pl. 6, fig. 1.

Conus marii (Sacco), 1893 — Hall 1966: 148, pl. 26, figs 21–22 [? figs 8, 15, 16].

Chelyconus marii Sacco, 1893 —Ferrero-Mortara 1984: 114, pl. 17, figs 8a–b.

Conus (Leptoconus) extensus Partsch—Chira & Voia 2001: 156 , pl. 2, figs 1a–b [non Conus extensus Hörnes, 1851 ].

Plagioconus marii (Sacco, 1893) — Kovács & Vicián 2013: 81 (partim), figs 101–105 [non fig. 108 = Plagioconus austriaconoe (Sacco, 1893) ].

non Conus (Chelyconus) marii Sacco—Chira & Voia 2001: 156 , pl. 4, figs 2a–b.

Type material. Lectotype BS.038.05.020 in Museo Regionale di Scienze Naturali, Torino; Albugnano ( Italy), middle Miocene, illustrated in Sacco (1893b, pl. 6, fig. 1); designated herein.

Studied material. 2 spec. NHMW 1846/0037/0025, 1 spec. NHMW 1851 /0013/0019, Vöslau ( Austria) ; 1spec. NHMW 1874/0024/0001, 1 spec. NHMW 1869 /0001/0160, Baden ( Austria) ; 5 spec NHMW 2013 /0300/ 0 529 (4 spire fragments) Baden-Soo ( Austria) .

Illustrated material. Figs 30 I, 32F1–F3: Baden-Soo ( Austria): SL: 67.0 mm, MD: 21.0 mm, NHMW 2013/ 0300/0529; Figs 32 G1–G3: Vöslau ( Austria): SL: 67.8 mm, MD: 23.4 mm, NHMW 1846/0037/0025.

Revised description. Moderately large shell with maximum height of nearly 70 mm; elongate outline with elevated conical spire comprising at least 13 whorls; spire height varies considerably. Early spire whorls angulated and beaded. Later spire whorls subangular without beads, with faint spiral grooves strongest along the angulation and below. Deeply incised suture; subsutural flexure very deep, moderately curved, strongly asymmetrical. Last whorl with strongly rounded shoulder and position of maximum diameter close below shoulder; straight sided with very slight constriction at base. Aperture narrow, narrowing adapically. Inner lip with callous notch and weak parietal callus. Siphonal canal moderately long, straight; fasciole indistinct, slightly twisted. Last whorl with narrow, finely wavy spiral grooves over lower half of last whorl.

Shell measurements and ratios. n = 4 adult and subadult specimens: largest specimen: SL: 67.8 mm, MD: 23.4 mm, mean SL: 64 mm (σ = 5.4), mean MD: 21.4 mm (σ = 1.5), spire angle: µ = 55.3° (σ = 3.8°), last whorl angle: µ = 24.8° (σ = 1.0°), LW: µ = 2.99 (σ = 0.16), RD: µ = 0.47 (σ = 0.01), PMD: µ = 0.93 (σ = 0.01), RSH: µ = 0.29 (σ = 0.03).

Discussion. The Paratethyan shells are very well preserved and show even the delicate beads on the early spire and the spiral sculpture on spire whorls and last whorl. These features are not preserved in the Italian type specimens but the size and general shape agree well. Unfortunately, Sacco (1893b) based this species on occurrences from different early and middle Miocene localities in the Turin Hills. These specimens represent syntypes and therefore, the designation of a holotype as proposed by Hall (1966) is inappropriate. To clarify this situation. the specimen from the middle Miocene of Albugnano illustrated by Sacco (1893b, pl. 6, fig. 1) is designated herein as the lectotype (inventory number BS.038.05.020 according to Ferrero-Mortara et al. 1984).

In the NHMW collections this species was mixed with P. puschi due to the superficial similarity in outline. Its rareness in the Paratethys might thus rather be an artefact. It differs from P. puschi and P. elatus in the shorter last whorl, the comparatively higher spire and higher spire whorls, the deep subsutural flexure and the smaller size. Moreover, the occurrences in coastal shallow water settings ( P. puschi , P. elatus ) versus offshore clays ( P. marii ) suggest an ecological and bathymetric separation.

Paleoenvironment. The species is only known from offshore clays of the inner to outer shelf.

Distribution in Paratethys. Badenian (middle Miocene): Vienna Basin: Bad Vöslau, Baden, Baden-Sooß ( Austria) (own data); Pannonian Basin: Letkés ( Hungary) ( Kovács & Vicián 2013); Transylvanian Basin: Lăpugiu de Sus ( Romania) ( Chira & Voia 2001).

Proto-Mediterranean Sea and northeastern Atlantic. Burdigalian ( Italy: Colli Torinesi), Langhian ( Italy: Albugnano).

Figures

FIGURE 32 A 1 – A 3. Plagioconus elatus (Michelotti, 1847), Gainfarn (Austria), NHMW 1855 / 0045 / 0367. 32 B 1 – B 2. Plagioconus elatus (Michelotti, 1847), Grinzing (Austria), NHMW 1846 / 0037 / 0023. 32 C 1 – C 3. Plagioconus extensus (Hörnes, 1851), Lăpugiu de Sus (Romania), NHMW 1890 / 0001 / 0011. 32 D. Plagioconus extensus (Hörnes, 1851), Lăpugiu de Sus (Romania), NHMW 1859 / 0037 / 0001. 32 E 1 – E 3. Plagioconus extensus (Hörnes, 1851), Baden-Sooß (Austria), NHMW 1872 / 0030 / 0017. 32 F 1 – F 3. Plagioconus marii (Sacco, 1893), Baden-Soo (Austria), NHMW 2013 / 0300 / 0529. 32 G 1 – G 3. Plagioconus marii (Sacco, 1893), Vöslau (Austria), NHMW 1846 / 0037 / 0025. 32 H. Plagioconus hirmetzli (Kovács & Vicián, 2013), Letkés (Hungary), private collection of T. Hirmetzl, paratype. 32 I. Plagioconus hirmetzli (Kovács & Vicián, 2013), Letkés (Hungary). private collection of T. Hirmetzl, paratype. 32 J. Plagioconus hirmetzli (Kovács & Vicián, 2013), Letkés (Hungary), HNHM, PAL 2013.3. 1, holotype.