Euspira protracta ( Eichwald, 1830 )

Pedriali, Luca, Sosso, Maurizio & Dell’Angelo, Bruno, 2019, Naticid gastropods from the middle Miocene of western Ukraine, Zootaxa 4700 (2), pp. 151-195 : 172-175

Euspira protracta ( Eichwald, 1830)

(Fig. 27.1−8)

Natica protracta Eichwald, 1830: p. 218 .

Natica protracta: Eichwald 1840, p. 9 ; Eichwald 1851, p. 124, pl. 10, fig. 43; Eichwald, 1853, p. 255; Eichwald 1859, pl. 10, fig. 43a, b.

? Natica helicina (non Brocchi, 1814): Du Bois de Montpéreux 1831, p. 44, pl. 3, fig. 44; Laskarev, 1914, p. 645.

? Natica (Lunatia) catena var. helicina (non Brocchi, 1814): Friedberg 1923, p. 429, pl. 26, figs 4, 5.

? Natica catena var. prohelicina (non Sacco, 1891): Friedberg, 1923, p. 432, text-fig. 77.

Type material. Natica protracta Eichwald, 1830 , type material not seen. The syntypes of this species were probably housed in the Zoological Institute of the Russian Academy of Sciences in St. Petersburg ( Russia), but they have not been found and are possibly lost.

Material examined. Varovtsi: MPUM 11741 (1 shell, Fig. 27.1a–c); MZB 32148 (1 shell, Fig. 27.2a-b); IGS NANU B-III-7/2018 (1 shell, Fig. 27.3a–c); MPUM 11742 (1 shell, Fig. 27.8a–c); ZISP 3/62198 (1 shell); NP 10027 (2 shells). Zalistsi: MZB 50518 (1 shell, Fig. 27.6a–b); MPUM 11743 (1 shell, Fig. 27.7); MZB 32149 (1 shell). Tarnoruda: ZISP 1/62196 (1 shell, Fig. 27.4a–b); ZISP 1/62197 (1 shell, Fig. 27.5).

Description. Protoconch small, turbiniform, of 2.0−2.1 convex whorls, tip small; protoconch I bearing un- evenly noded, evenly spaced spiral threads over abapical two-thirds. Teleoconch small, globose, higher than wide, moderately thick. Spire conical, rather elevated, whorls gently convex; suture fine, adpressed. Last whorl globoseoval, slightly extended toward aperture; subsutural shelf indistinct; periphery above midline. Aperture D-shaped in slightly prosocline plane; outer lip semicircular, inner lip nearly straight. Parietal callus thick, subquadrangular, with concave abapertural outline, ending at level of umbilical border with pointed, small anterior lobe. Umbilicus deep, moderately wide to small, subtriangular, rounded abapically, angular adapically. Umbilical wall arched, basal fasciole indistinct. Funicle small, depressed, separated from umbilical wall by shallow spiral furrow and merging into anterior lobe of parietal callus. Outer surface with fine growth lines; microscopic spiral striation present on last whorl. One well preserved specimen retains uniform whitish background with pattern of uneven pale-brown collabral stripes, darker subsuturally.

Remarks. Eichwald (1830) introduced the new species Natica protracta on the base of material from Sawa- dynze (= Zavadyntsi), Ukraine. He published ( Eichwald 1830, p. 218) a concise diagnosis without figures: “ Testa elongato-ovata, spira elongato-protracta, apertura semicirculari, umbilico magno laterali; color fusco-rufus ” [Elongated oval shell, spire elevated and protracted, aperture semicircular, umbilicus large and lateral; reddishbrown color]. Pusch (1837, p. 101), included with doubt Eichwald’s species in the synonymy of Natica hemiclausa J. Sowerby, 1824 . Three years later, Eichwald (1840, p. 9) confirmed the validity of his species stating that “ Meine Natica protracta … ve schieden von der N. hemiclausa Sow. , mit der sie H. Pusch verwechselt ” [My Natica protracta … is separated from N. hemiclausa Sow. with which she was confused by H. Pusch] and that his short diagnosis of the species was sufficient for species separation. Finally, Eichwald (1853, p. 255) published an exhaustive description and a good figure (1859, pl. 10, fig. 43) of a shell of N. protracta , without specifying the collecting locality among those listed, i.e., Zukowce, Zawadynce and Korytnice (= Zhukivtsi, Zavadyntsi and Korytnytsya). We have examined good quality photographs of three shells from Eichwald’s collection housed in the Zoological Institute, St. Petersburg ( Russia), and of the manuscript label accompanying these shells; on this label it is written ‘ Natica protracta, Eichw., Tarnaruda (510)’ (= Tarnoruda). According to Boris Sirenko (pers. comm.), it is not sure whether these shells are Eichwald’s syntypes, and other inquiries about the location of Eichwald’s type material gave negative results. In addition, Tarnoruda is not one of the collecting localities of this species listed by Eichwald in his papers; Tarnoruda is cited only referring to another species, N. eximia . We have selected and figured (Fig. 27.4 and 5) two of these specimens, but neither is eligible to be the lectotype of the species, since their status of possible syntypes need to be confirmed. They appear to be strikingly similar in teleoconch shape and umbilical characters to some specimens collected by one of the present authors (BD) from Varovtsi and Zalistsi, which we assign to N. protracta . Two of these specimens, one from Varovtsi and one from Zalistsi, retain a well preserved protoconch.

Euspira protracta is very similar in teleoconch shape to E. helicina helicina (Fig. 27.9−27.11), a subspecies known from the Burdigalian to the late Pliocene of Europe and from the Serravallian of Turkey. However, E. protracta is readily distinguished from E. helicina helicina in having a protoconch of about 0.5 fewer whorls with protoconch I sculptured with more numerous spiral threads present over the abapical two-thirds of it and not only over its most abapical part as in E. helicina helicina .

The Pliocene to Recent ( Harmer 1921, p. 698) North European species Natica hemiclausa (Fig. 27.12) is superficially similar to E. protracta , but can be easily distinguished from it by having a protoconch with a smaller diameter of the first half-whorl, a spire with more flattened whorls, and a longer parietal callus largely covering an umbilicus with a shallower inner spiral furrow.

In order to clarify the relationships between Euspira protracta and E. helicina helicina, Janssen (1969, 1984 ) examined several specimens from the Reinbekian (middle Miocene) deposits of Dingden, Germany ( Janssen 1969), and from the Hemmorian (early Miocene) deposits of Winterswijk-Miste, the Netherlands ( Janssen 1984); only on the basis of teleoconch characters he affirmed that the first species was to be considered a subspecies of the latter, and referred the German specimens ( Janssen 1969, pp. 163, 165) to as Polinices (Euspira) helicinus protractus ( Eichwald, 1830) and Polinices (Euspira) helicinus helicinus ( Brocchi, 1814) , and the Dutch shells ( Janssen 1984, p. 197) to as Euspira helicina protracta ( Eichwald, 1830) .

Bałuk (1995, p.196, pl. 15, figs 2–3), used the name Polinices protractus ( Eichwald, 1853) for specimens from lower Badenian of Korytnica, Poland, on the basis of teleoconch characters and of the assumption that the holotype of this species was coming from this locality. We examined some similar specimens from this outcrop and noted that they surely belong to another species because they have a protoconch with smaller diameter of the first half-whorl; in addition, Eichwald (1830, p. 218) created the species Natica protracta based on material from another locality, Sawadynze (=Zavadyntsi), Ukraine (see remarks above).

Thus, the presence of E. protracta in Janssen’s and Bałuk’s materials could be confirmed only by protoconch examination and therefore the specimens cited and figured by these authors are herein excluded from the synonymy of the species.

More recently, Landau et al. (2013, p. 105), summarized the complex nomenclatural history of E. protracta , concluding that Eichwald’s taxon is to be considered a valid species, and that it is readily distinguished from E. helicina helicina ( Brocchi, 1814) on the basis of teleoconch differences.

From the above, it may be concluded that the presence of E. protracta outside Ukraine needs to be confirmed by the recovery of specimens retaining the protoconch.

Distribution. Middle Miocene: Central Paratethys (Upper Badenian) in Ukraine (this paper).