Mitrella demaintenonae, Harzhauser & Landau, 2021

Harzhauser, Mathias & Landau, Bernard M., 2021, The Columbellidae (Gastropoda, Buccinoidea) in the Miocene Paratethys Sea — striking diversity of a negelected group, Zootaxa 5025 (1), pp. 1-75 : 23-24

publication ID	https://doi.org/ 10.11646/zootaxa.5025.1.1
publication LSID	lsid:zoobank.org:pub:35E6C8FA-4078-4C53-9B74-F9618D5E6E60
persistent identifier	https://treatment.plazi.org/id/256F7D50-E27D-FFF7-ACD6-341CFBB0B389
treatment provided by	Plazi
scientific name	Mitrella demaintenonae
status	sp. nov.

Treatment

Mitrella demaintenonae nov. sp.

Figs 4B, 9E View FIGURE 9 1 –E View FIGURE 1 2 View FIGURE 2 , F 1 –F View FIGURE 1 2 View FIGURE 2 , G 1 –G View FIGURE 1 2 View FIGURE 2 , H

Columbella (Mitrella) Petersi nov. form.— Hoernes & Auinger 1880: 97 (pars), pl. 12, figs 7a–c [non Mitrella petersi Hilber, 1879 ].

Columbella (Mitrella) carinata Hilber View in CoL — Hoernes & Auinger 1880: 97 (pars), pl. 12, figs 10–11 [non Mitrella hilberi ( Cossmann, 1901) ].

Columbella sp. — Caze et al. 2010: 32, figs 5K 1 –K 2.

Type material. Holotype: NHMW 2020 View Materials /0161/0001, SL: 12.5 mm, MD: 4.0 mm, Coşteiu de Sus ( Romania), Figs 4B, 9G View FIGURE 9 1 –G View FIGURE 1 2 View FIGURE 2 . Paratypes: NHMW 2020 View Materials / 0161/0002, SL: 11.1 mm, MD: 3.4 mm, Coşteiu de Sus ( Romania), Figs 9E View FIGURE 9 1 – E View FIGURE 1 2 View FIGURE 2 . NHMW 2020 View Materials / 0161/0002, SL: 11.9 mm, MD: 3.7 mm, Coşteiu de Sus ( Romania), Figs 9F View FIGURE 9 1 –F View FIGURE 1 2 View FIGURE 2 . NHMW1867 View Materials /

0019/0049b, SL: 12.1 mm, MD: 3.3 mm, Coşteiu de Sus ( Romania), illustrated in Hoernes & Auinger (1880, pl. 12, figs 11a–c) as Columbella (Mitrella) carinata , Fig. 9H View FIGURE 9 . NHMW 1878/0001/0081, SL: 12.0 mm, MD: 3.6 mm, Möllersdorf, illustrated in Hoernes & Auinger (1880, pl. 12, figs 7a–c) as Columbella (Mitrella) Petersi.

Additional material. NHMW1867 View Materials /0019/0049a, SL: 12.4 mm, MD: 4.1 mm, Coşteiu de Sus ( Romania), illustrated in Hoernes & Auinger (1880, pl. 12, figs 10a–c) . NHMW2020 View Materials /0177/0002 (ex B. Landau coll.), 9 spec., Gainfarn ( Austria) .

Type locality. Coşteiu de Sus ( Romania), Făget Basin .

Type stratum. Silt and clay of the Dej Formation.

Age. Middle Miocene, Badenian.

Etymology. In honour of Marta deMaintenon (University of Hawaii) in recognition of her contributions on Columbellidae .

Diagnosis. Mitrella species of moderately small size, slender fusiform, with multispiral protoconch, acute spire, weakly convex spire whorls, spirals restricted to siphonal fasciole, faint basal angulation, columellar callus weakly developed, without denticles. Distinguished from similar Paratethyan species by its moderately wide aperture.

Description. Shell moderately small, slender fusiform, with high spire, and narrowly incised suture. Conical multispiral protoconch of about 3.5 whorls. Teleoconch of eight whorls. First teleoconch whorl slightly narrower than last protoconch whorl. Spire whorls only weakly convex with periphery slightly below mid-whorl. Last whorl weakly convex with rounded basal angulation, moderately to strongly constricted at base. Shell smooth except for faint spiral threads visible only in best preserved specimens; prominent spiral cords restricted to siphonal fasciole. Aperture moderately wide, elongate ovoid. Outer lip slightly thickened with eight to ten small prominent denticles within. Anal canal shallow, U-shaped. Siphonal canal moderately long, moderately narrow, straight to slightly deflected, notched at tip. Columella slightly twisted forming indistinct fold. Columellar callus forming thin, narrow rim, weakly delimited from base. No columellar denticles. Parietal callus hardly developed. Colour pattern consisting of large blotches or flammulae at adapical and abapical suture, intercalated by spiral band of smaller irregular dots. Base also covered by close-set dots (see Caze et al. 2010, figs 5K 1 –K 2).

Shell measurements and ratios. SL: 11.1–12.5 mm, MD: 3.3–4.1 mm, AA: 25–28°, SL/MD: 3.2–3.3, AL/AW: 3.3–3.4, LWH/AH: 1.3–1.4.

Discussion. This species was mixed with Mitrella elongatissima nov. sp. in the collections of the NHMW due to the similar elongate outline. Mitrella demaintenonae , however, differs in its wider apical angle, wider aperture and the taller conical protoconch. In addition, both species seem to have been ecologically separated. Mitrella elongatissima is documented from inner neritic environments with sea grass whereas M. demaintenonae derives from offshore clay.

Palaeoenvironment. Middle neritic to outer neritic. The specimens from the Vienna Basin are found in clay of the Baden Fm., suggesting about 250 m water depth ( Hohenegger et al. 2008).

Distribution in Central Paratethys. Badenian (middle Miocene): Vienna Basin: Baden, Gainfarn, Möllersdorf ( Austria) (own data); Făget Basin: Coşteiu de Sus ( Romania) ( Boettger 1906).