Monostiolum hungaricum ( Csepreghy-Meznerics, 1954 )

Harzhauser, Mathias & Landau, Bernard M., 2024, The Colubrariidae, Eosiphonidae, Melongenidae, Pisaniidae, Prodotiidae and Tudiclidae (Gastropoda, Buccinoidea) of the Miocene Paratethys Sea, Zootaxa 5427 (1), pp. 1-110 : 49-51

Monostiolum hungaricum ( Csepreghy-Meznerics, 1954)

Figs 15H , 25A–D

Triton varians Michti. —Hörnes 1856: 670, pl. 51, figs 3a–b [non Monostiolum varians ( Michelotti, 1847) ].

Pollia varians Michti. —Hoernes & Auinger 1890: 240 [non Monostiolum varians ( Michelotti, 1847) ].

* Philbertia hungarica n. sp. — Csepreghy-Meznerics 1954: 54, 142, pl. 7, figs 16–17, 21–22.

C [antharus]. (P [ollia]). varians (Micht.) — Sieber 1958: 151 [non Monostiolum varians ( Michelotti, 1847) ].

“ Philbertia ”(?) hungarica Csepreghy-Meznerics — Strausz, 1966a: 444, pl. 79, fig. 4.

Philbertia hungarica Csepreghy-Meznerics —Pálfy et al. 2009: 108.

Aplus varians ( Michelotti, 1847) — Vicián et al. 2017: 270, pl. 3, figs 1–3 [non Monostiolum varians ( Michelotti, 1847) ].

Aplus varians ( Michelotti, 1847) — Kovács & Vicián 2023: 252, figs 12H–I [non Monostiolum varians ( Michelotti, 1847) ]. Type material. Holotype: M. 52/1441, Hungarian Natural History Museum, Budapest, SL: 10.9 mm, MD: 4.3 mm, Sámsonháza ( Hungary), Badenian (Middle Miocene), illustrated in Csepreghy-Meznerics 1954 (pl. 7, figs 16–17, 21–22).

Illustrated material. NHMW 2023/0348/0003, SL: 15.1 mm, MD: 5.7 mm, Steinebrunn ( Austria), Figs 25A 1 – A 2 . NHMW 1869/0001/0348, SL: 14.3 mm, MD: 5.5 mm, Steinebrunn ( Austria); illustrated in Hörnes (1856: pl. 51, fig. 3), Figs 25B 1 –B 2 . NHMW 1865/0001/0561, SL: 14.9 mm, MD: 5.7 mm, Steinebrunn ( Austria), Fig. 25C . NHMW 1868/0001/0094, SL: 16.5 mm, MD: 5.9 mm, Steinebrunn ( Austria), Figs 15H , 25D .

Additional material. 53 spec., NHMW 1871 /0010/0338, Steinebrunn ( Austria) ; 1 spec., NHMW 2023 /0348/0004, Steinebrunn ( Austria) ; 2 spec., NHMW 1863 /0015/0658, Niederleis ( Austria) ; 2 spec., NHMW 1862 /0033/0023, Pöls ( Austria) ; 21 spec., NHMW 1870 /0033/0075, Lăpugiu de Sus ( Romania) ; 8 spec., NHMW 1855 /0043/0012, Lăpugiu de Sus ( Romania) .

Revised description. Medium-sized, slender shell of up to six teleoconch whorls with weakly cyrtoconoid spire; apical angle ~50°. Protoconch moderately high conical of three weakly convex whorls; diameter: 680 μm, height: 620 μm. Second protoconch whorl weakly carinate below mid-whorl. Early teleoconch whorls weakly convex, periphery close above deeply incised suture. Sculpture of broad, prominent axial ribs, separated by slightly narrower interspaces, overrun by three broad spiral cords weakly swollen over ribs. On second teleoconch whorl adapical spiral cord splits into two primary cords. Later whorls strongly increasing in height, becoming increasingly convex. Single secondary cord becomes intercalated in each spiral interspace, rapidly increasing in strength and becoming equal to primaries in some specimens ( Figs 25A, B, D ), or remaining slightly weaker in others ( Fig. 25C ). Last whorl attaining ~40% of total height, moderately convex, with moderately constricted base, bearing about 18–20 subequal spiral cords, swollen to weakly nodulose over ribs, with occasional tertiary thread intercalated in some interspaces; fasciole broad, indistinct with prominent spiral cords. Aperture narrow, ovate, Columella weakly excavated, distinctly angled at transition to siphonal canal, accentuated by prominent denticle, smooth above. Columellar callus forming broad, prominent rim, sharply delimited from base. Anal canal moderately incised Ushaped, adjoined by low parietal denticle. Outer lip thickened by terminal varix, with about 10–12 prominent, elongate denticles slightly behind peristome, lowermost denticle at transition to siphonal canal slightly stronger, oriented in axial direction. Siphonal canal moderately short, wide, shallowly notched, slightly deflected to the left.

Discussion. Kovács & Vicián (2023) studied the holotype of Philbertia hungarica Csepreghy-Meznerics, 1954 and recognized that it was conspecific with the species described by Hörnes (1856) and (Hoernes &Auinger 1890) as Triton varians and Pollia varians respectively. Monostiolum hungaricum was identified as Triton varians Michelotti, 1847 by Hörnes (1856) and subsequent authors. The Italian species was illustrated in Michelotti (1847: 250, pl. 16, fig. 10). In addition, we consider Pollia angusta Bellardi, 1873 to be conspecific with Monostiolum varians (see Bellardi 1873: 181, pl. 12, fig. 20). Based on these two illustrations, Monostiolum hungaricum differs from M. varians in its higher spire, more convex whorls and more deeply incised suture. In his Latin description, Bellardi (1873: 181) emphasized the prominent axial ribs and weak spiral sculpture of M. varians , whereas the Paratethyan species has weak axial ribs and prominent spiral sculpture. Nevertheless, better illustrations and descriptions of M. varians will be needed to clarify its relation to M. hungaricum . The specimen illustrated by Kovács & Vicián (2023) has an extra varix at 180 degrees from the terminal varix and is not fully grown. Its terminal varix is not fully formed and labial denticles are absent.

The specimen illustrated by Bellardi (1873: 180, pl. 12, fig. 19) as Pollia varians has a short spire and an inflated last whorl and is placed herein in Dianthiphos . Tritonidea productocostata Sacco, 1904 , established as subspecies of Tritonidea varians by Sacco (1904: 59, pl. 14, figs 69–70) differs from M. varians and M. hungaricum in its fewer and wider spaced spiral cords. This species is also placed in Dianthiphos by us.

Paleoenvironment. Shallow marine, inner neritic.

Distribution in Central Paratethys. Badenian (Middle Miocene): Vienna Basin: Steinebrunn, Niederleis ( Austria) (Hoernes & Auinger 1890); Styrian Basin: Pöls ( Austria) (Hoernes & Auinger 1890); Pannonian Basin: Bánd, Letkés, Márkháza ( Hungary) ( Vicián et al. 2017); Bükk Mountains: Borsodbóta ( Hungary) ( Vicián et al. 2017); Făget Basin: CoŞteiu de Sus, Lăpugiu de Sus ( Romania) (Hoernes & Auinger 1890).

Figures

FIGURE 1. Measurements for shell morphology; AA: apical angle, SL: shell length, MD: maximum diameter, LWH: last whorl height, AH: aperture height, AL: aperture length, AW: aperture width.

FIGURE 2. Colubraria subobscura (Hoernes & Auinger, 1884). A1–A3. NHMW 1854/0035/0170, paralectotype, Lăpugiu de Sus (Romania). B1–B2. NHMW 1859/0037/0018a, paralectotype, Lăpugiu de Sus (Romania). C1–C3. NHMW 1865/0001/0183, paralectotype, Lăpugiu de Sus (Romania). D1–D2. NHMW 1859/0037/0018b, paralectotype, Lăpugiu de Sus (Romania). E1–E3. NHMW 1874/0025/0021, lectotype, Lăpugiu de Sus (Romania). F1–F2. NHMW 2023/0338/0001, paralectotype, Lăpugiu de Sus (Romania).

FIGURE 15. Protoconchs of Paratethyan Pisaniidae, Prodotiidae and Tudiclidae. A. Aplus moravicus (Hoernes & Auinger, 1890), NHMW 1862/0029/0034, lectotype, Rudice u Blanska (Czech Republic). B. Aplus subpusillus (Hoernes & Auinger, 1890), NHMW 1866/0001/1066, paralectotype, Forchtenau (Austria). C. Aplus transsylvanicus (Hoernes & Auinger, 1890), NHMW 1873/0026/0019b, lectotype. D. Aplus zebus (De Gregorio, 1885a), NHMW 1855/0045/0439, Gainfarn (Austria). E. Aplus anatolicus nov. sp. RGM 784 005, paratype, Seyithasan (Turkey). F. Hilda transsylvanica (Hoernes & Auinger, 1884), NHMW 1876/0011/0023a, lectotype, Lăpugiu de Sus (Romania).G. Janiopsis vindobonensis nov. sp., NHMW 1850/0009/0002, holotype, Baden (Austria). H. Monostiolum hungaricum (Csepreghy-Meznerics, 1954), NHMW 1868/0001/0094, Steinebrunn (Austria). I. Dianthiphos klaudiae (Kovács & Vicián, 2023), NHMW1846/0037/0144a, Steinebrunn (Austria). J. Euthria obelixi nov. sp., NHMW 1865/0015/0060, holotype, Lysice (Czech Republic). K. Tethyspollia mariae (Hoernes & Auinger, 1890), NHMW 1868/0001/0441, paralectotype, Lăpugiu de Sus (Romania).

FIGURE 25. Monostiolum hungaricum (Csepreghy-Meznerics, 1954). A1–A2. NHMW 2023/0348/0003, Steinebrunn (Austria). B1–B2. NHMW 1869/0001/0348, Steinebrunn (Austria). C. NHMW 1865/0001/0561, Steinebrunn (Austria). D. NHMW 1868/0001/0094, Steinebrunn (Austria).