Archimediella Sacco 1895

Harzhauser, Mathias & Landau, Bernard, 2019, Turritellidae (Gastropoda) of the Miocene Paratethys Sea with considerations about turritellid genera, Zootaxa 4681 (1), pp. 1-136 : 24-26

Genus Archimediella Sacco 1895

Type species: Turritella archimedis Brongniart, 1823 (non Dillwyn, 1817) [= Archimediella cochlias ( Bayan, 1873) ], by original designation ( Sacco 1895: 12). Rupelian (early Oligocene), Italy.

Remarks. Brongniart (1823) erroneously indicated Roncà in the Province of Verona in the Italian region Veneto as type locality of Turritella archimedis , which would suggest a middle Eocene age (Bartonian). Fuchs (1870: 137), however, documented that many specimens that were thought by Brongniart (1823) to derive from Roncà were collected at the Rupelian locality Sangonini ( Italy). Bayan (1873: 96) recognized that Turritella archimedis Brongniart, 1823 is a homonym of Turritella archimedis ( Dillwyn, 1817) [a Recent turritellid, which is currently considered to be a junior synonym of Turritella terebra ( Linnaeus, 1758) (MolluscaBase 2018e) ], and proposed Turritella cochlias as replacement name, pointing out its Oligocene age.

Based on the fossil type species, the genus Archimediella is characterized by its corkscrew-like early teleoconch whorls, on which the primaries B and C form two main keels. The lateral sinus of Archimediella cochlias is not visible in the material available to us. We doubt that the LS of Archimediella given in Marwick (1957, fig. 3) is based on this rather rare species, because he refers to the figure of Brongniart (1823), which does not show any growth lines. The lateral sinus of Archimediella abundans ( Handmann, 1882) is moderately deep with slight adapical inflection point and a distinct abapical inflection point passing via a prosocyrt sinus into a weakly opisthocyrt basal sinus. This morphology differs slightly from Marwick’s figure, which lacks an abapical inflection point.

Inner lirae are (occasionally) present in the investigated species ( A. abundans , A. carpathica , A. indigena , A. hoernesi ) typically consisting of 7–8 distinct lirae on the palatal wall (= outer free wall of whorl) and a prominent basal cord accompanied by 0–3 weaker cords. Palatal lirae are very weak in A. indigena , but a basal cord is present as well.

The neanic whorls of Archimediella cochlias are nearly indistinguishable from A. abundans ( Figs 10 A–B versus Figs 10 C–F). The main difference between the species is the much smaller size of all known specimens of A. cochlias . This might be a disputable argument as no complete specimens of A. cochlias are documented so far. However, a clear difference is the tendency to form beaded primary spiral cords in A. cochlias , whereas the Miocene A. abundans lacks any beads on the primaries. In addition, the color pattern of A. cochlias differs from A. abundans . Its axial stripes are better defined, it lacks the dots present in A. abundans on the secondary spiral cords of the sutural ramp, and it lacks the continuous coloring along the primaries (see Caze et al. 2010).

Archimediella cochlias is a rarely reported species, originally described from the Rupelian of the Vento region in Italy ( Brongniart 1823; Fuchs 1870; Oppenheim 1900). The published illustrations are all small and somewhat schematic. Therefore, we provide pictures of two specimens collected at the type locality Sangonini di Lugo (GBA 2010/152/0055; SL: 23.7 mm, MD: 8.4 mm, Figs 10A 1 –A 4 ) and the close by Gnata di Salcedo (GBA 2010/148/0062; SL: 11.5 mm, MD: 4.1 mm, Fig. 10B ).

Archimediella cochlias seems to be present back to the late Eocene (Priabonian) of the Veneto region ( Rumi et al. 1973). Rupelian records from Liguria were described as A. archimedis laevicrassa Sacco, 1895 ( Sacco 1895, 1904). Chattian occurrences of Archimediella are reported from southern Italy ( Esu & Girotti 2010), Bavaria ( Hölzl 1962) and Hungary ( Báldi 1973) as A. thetis , A. archimedis and A. archimedis laevicrassa . The status of these occurrences is difficult to evaluate due to the rather poor preservation. The late Miocene specimens from the North Sea, described as A. cochlias and A. archimedis by Rasmussen (1956, 1968) and Roth & Hoedemakers (2005), are almost certainly not conspecific with the Rupelian species and will need revision.

The genus Archimediella originated at least during the late Eocene ( Rumi et al. 1973) and seems to be still living along the coast of West Africa and the Persian Gulf. Marche-Marchad (1960) and Garrard (1972) placed several additional extant West African and Indo-West Pacific and Australian species in Archimediella , but this needs revision in most cases.

Figures

FIGURE 1. Paleogeography of the Paratethys during the early Miocene (Burdigalian, Eggenburgian, Sakaraulian) and the middle Miocene (Langhian, Badenian, Tarkhanian) (modified after Popov et al. 2004 and Neubauer et al. 2015).

FIGURE 4. A. Measurements and ratios to classify lateral sinus morphology (LS° = lateral sinus angle, LSp = lateral sinus position, LSd = lateral sinus depth). B. Classification of lateral sinus angles; grey area represents angles documented in Paratethyan Turritellidae. C. Notation system for describing spiral cords in turritellids:A, B, C, d = primary spiral cords, r, s, t, u = secondary spiral cords (adopted from Allmon 1996).

FIGURE 10. A–B. Archimediella cochlias (Bayan, 1873). A1–A4. Sangonini di Lugo (Italy) GBA 2010/152/0055. B. Gnata di Salcedo, GBA 2010/148/0062. C–F. Archimediella abundans (Handmann, 1882). C. Steinebrunn (Austria), NHMW 1846/0037/0393. D1–D2. Steinebrunn (Austria), NHMW 1871/0010/0382. E1–E2. Lăpugiu de Sus (Romania), NHMW 1869/0019/0204. F1–F2. Steinebrunn (Austria), NHMW 1963/0518/0000. G–J. Archimediella hoernesi (Rolle, 1856). G1–G2. Wetzelsdorf-Kreuzschaller (Austria), UMJG&P 61.170. H1–H2. Neotype, Wetzelsdorf-Winkeltoni (Austria), UMJG&P 74.936- 1. I. Wetzelsdorf-Winkeltoni (Austria), UMJG&P 74.936-2. J. Guglitz (Austria), NHMW 1858/0020/0024.