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 : 135-136

Plagioconus extensus (Hörnes, 1851)

Figs 30 K, 32C1–C3, 32D, 32E1–E3

[ Conus ] extensus n. sp. — Hauer 1837: 416 (nomen nudum).

Conus extensus Partsch—Hörnes 1851: 37 , pl. 5, figs 1a–c.

Conus (Leptoconus) extensus Partsch—Hoernes & Auinger 1879: 34 .

Conus (Leptoconus) extensus Partsch—Csepreghy-Meznerics 1956: 421, pl. 11, figs 7–8.

? Conus (Leptoconus) extensus (Partsch in Hörnes 1856) —Kojumdgieva in Kojumdgieva & Strachimirov 1960: 210, pl. 49, fig. 6.

Conus (Leptoconus) extensus Partsch—Strausz 1966: 453 , pl. 67, figs 11–12.

Conus extensus Partsch—Wank 1981: 285 , pl. 1, fig. 2.

Conus (Phasmoconus) extensus Partsch—Schultz 1989: 72 , pl. 29, fig. 13.

Conus (Chelyconus) puschi Michelotti—Chira & Voia 2001: 156 , pl. 4, figs 1a–b [non Plagioconus puschi ( Michelotti, 1847) ].

Plagioconus extensus (Partsch in Hörnes, 1856) — Kovács & Vicián 2013: 79, figs 97–100.

Conus extensus Partsch—Fözy & Szente 2014: 311 , text-fig. 5.

non Conus (Leptoconus) extensus Partsch—Chira & Voia 2001: 156 , pl. 2, figs 1a–b [= Plagioconus marii (Sacco, 1893) ].

Type material. 2 syntypes NHMW 1847 /0037/0031, Baden ( Austria), including specimen illustrated in Hörnes (1851, pl. 5, fig. 1), middle Miocene , Badenian (late Langhian).

Studied material. Syntypes and 1 spec. NHMW 1869/0001/0159, 1 spec. NHMW 1997 z0178/0871, Badenian Baden ( Austria); 2 spec . NHMW 2015/0391/0001 including specimen illustrated in Schultz (1998, pl. 29, fig. 13), 3 spec. NHMW 1872/0030/0017, 10 spec. NHMW 2013 /0300/0525, all Baden-Sooß ( Austria); 1 spec . NHMW 1855 /0045/0370, Gainfarn ( Austria), 3 spec . NHMW 1854/00035/0053, 3 spec. NHMW 1854/0035/0052, 2 spec. NHMW 1855/0043/0003, 2 spec. NHMW 1859/0037/0001, 1 spec. NHMW 1868/0001/0384, 2 spec. NHMW 1866/0040/0247, 4 spec. NHMW 1875/0009/0005, 1 spec. NHMW 1875/0009/0004, 2 spec. NHMW 1890/0001/ 0 0 11, 2 spec. NHMW 1890/0001/0013, 2 spec. NHMW 1973/1615/0062, 3 spec. NHMW 2015/0392/0001, 8 spec. NHMW 2015/0392/0002, 2 spec. NHMW 1858 /0043/0004, all Lăpugiu de Sus ( Romania), 1 spec . NHMW 1867 / 0019/0010, Coşteiu de Sus ( Romania): 1 spec . NHMW 2015 /0393/0001, Nemeşeşti ( Romania).

Illustrated material. Figs 32 C1–C3: Lăpugiu de Sus ( Romania): SL: 89.3 mm, MD: 35.3 mm, NHMW 1890/ 0001/0011; Figs 32 D: Lăpugiu de Sus ( Romania), SL: 89.0, MD: 36.0 mm, NHMW 1859/0037/0001; Figs 30 K, 32E1–E3: Baden-Sooß ( Austria): SL: 96.0 mm, MD: 33.2 mm, NHMW 1872/0030/0017.

Revised description. Large shells comprising at least 10 tall teleoconch whorls; spire short, conical to weakly coeloconoid. Early whorls angular above suture with coarse beads, central angulation becoming mid-whorl inflation abapically. Sutural ramp bearing subsutural collar/band and spiral striae developed to a variable degree; ramp becoming increasingly concave abapically. Suture deeply impressed. Subsutural flexure very deep, moderately curved, strongly asymmetrical. Last whorl very elongate, weakly constricted at base; moderately round shoulder with position of maximum diameter a short distance below shoulder. Aperture narrow, widening abapically. Siphonal canal long, weakly recurved; fasciole elongate, slightly twisted and demarcated from narrow glossy inner lip by a narrow notch. Base covered by very delicate spiral grooves on adapical half; grooves become stronger and wider abapically; usually somewhat irregular and pitted. Colour pattern in UV light consisting of light flammulae on spire whorls and shoulder of last whorl parallel to subsutural flexure; indistinct bands on last whorl.

Shell measurements and ratios. n = 12 adult and subadult specimens: largest specimen: SL: 107 mm, MD: 39 mm, mean SL: 88.2 mm (σ = 10.4), mean MD: 32 mm (σ = 3.7), spire angle: µ = 82.7° (σ = 4.3°), last whorl angle: µ = 22.3° (σ = 1.7°), LW: µ = 2.76 (σ = 0.19), RD: µ = 0.44 (σ = 0.03), PMD: µ = 0.95 (σ = 0.02), RSH: µ = 0.17 (σ = 0.03).

Discussion. This species is characterized by the concave sutural ramp bearing spiral striae, the distinct but rounded shoulder and rather moderate variability in outline. The largest variability is represented by the more or less prominent spiral sculpture. Hörnes (1851) had only a single complete specimen at hand, which has been largely destroyed thereafter; only the spire is preserved. Since then, numerous shells were collected at Baden, Baden-Sooß and Lăpugiu de Sus.

Paleoenvironment. The majority of shells were collected in basinal clays. In contrast, only a single specimen was found in the seagrass environment of Gainfarn ( Austria). This suggests that Plagioconus extensus was probably an offshore species.

Distribution in Paratethys. Badenian (middle Miocene): Alpine-Carpathian Foredeep: Grund ( Austria) ( Sieber 1947); Vienna Basin: Baden, Baden-Sooß, Gainfarn, Steinebrunn ( Austria) ( Hoernes & Auinger 1879; Sieber 1958b); Lavanttal Basin: Mühldorf ( Austria) (Wank 1981); Pannonian Basin: Hont, Letkés, Szob ( Hungary) ( Kovács & Vicián 2013); Transylvanian Basin: Lăpugiu de Sus, Coşteiu de Sus, Nemeşeşti ( Romania) ( Boettger 1902, 1906; Chira & Voia 2001); Dacian Basin: Opanec ( Bulgaria) ( Kojumdgieva & Strachimirov 1960). No reliable occurrences from the proto-Mediterranean Sea are known to date.

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.