Tectonatica anistratenkorum, Pedriali & Sosso & Dell’Angelo, 2019

Pedriali, Luca, Sosso, Maurizio & Dell’Angelo, Bruno, 2019, Naticid gastropods from the middle Miocene of western Ukraine, Zootaxa 4700 (2), pp. 151-195 : 168-170

Tectonatica anistratenkorum sp. nov.

(Fig. 25.1−5)

Type material. Holotype and 4 paratypes ( Table 7 ).

Type locality. Varovtsi , Ukraine .

Type stage. Middle Miocene (Upper Badenian) .

Etymology. The species is named after Vitaliy and Olga Anistratenko (Schmalhausen Institute of Zoology of NAS Ukraine and Institute of Geological Sciences of NAS Ukraine), for their contribution to the study of Recent and fossil molluscs.

Other material. Varovtsi: MZB 50517 (1 operculum, Fig. 25.4a-b); NP 10025 (2 shells); BD 165 (1 shell); MS 104 (1 shell). Zalistsi: NP 10032 (1 shell).

Diagnosis. Globose shell with conical spire and inflated last whorl. Umbilicus completely plugged or with a semicircular mid-abapical chink in a few specimens. Umbilical callus thick, wide, in middle of inner lip, semicircular, not separated from parietal callus. Parietal callus thin, subrectangular. Basal fasciole poorly differentiated. Colour pattern composed of darker subsutural band and uneven whitish to brown collabral lines over light brown background. Operculum with smooth outer surface incised by very narrow, distinct marginal groove and with flat central callus slightly protruding abapically.

Description. Protoconch small, depressed turbiniform, of 2.50−2.75 gently convex, apparently smooth whorls, tip very small. Teleoconch globose, thick. Spire conical, moderately elevated, whorls gently convex, suture fine, adpressed. Last whorl inflated, rather depressed, slightly produced toward aperture. Subsutural shelf indistinct, periphery above midline. Aperture D-shaped in prosocline plane. Parietal callus subrectangular, rather thin. Umbilicus completely or partially filled by umbilical callus (in latter case, a semicircular mid-abapical chink). Funicle not visible in most specimens; only one specimen with more open umbilicus shows broad and thick funicle. Umbilical callus wide, rather thick, located at middle of inner lip, semicircular in outline, not separated from parietal callus. Abapertural outline of inner lip calluses (parietal + umbilical) concave. Basal fasciole poorly differentiated. Surface with rather dense, thin growth lines, stronger on basal fasciole; microscopic spiral striation present on body whorl. Background uniform pale brown, with pattern of uneven whitish to brown collabral lines and darker subsutural band. Operculum with smooth outer surface incised by very narrow, distinct marginal groove bounding narrow peripheral area, and with flat central callus slightly protruding abapically.

Remarks. Tectonatica anistratenkorum sp. nov. is identical to the Burdigalian to late Pliocene European species T. tectula in teleoconch shape, but can be distinguished from it because of its protoconch with a smaller diameter (average values 0.798 mm and 1.107 mm, respectively). The late Miocene (Tortonian) to late Pliocene Italian species T. astensis (Fig. 25.10−13) and the Pliocene to Recent (western Mediterranean and eastern Atlantic) species T. prietoi (Fig. 25.14−16) are similar to T. anistratenkorum sp. nov., but can be easily differentiated from it in that the protoconch has a greater diameter of the first half-whorl (average values 0.111 mm, 0.120 mm and 0.081 mm, respectively, and also the protoconch diameter, with an average value of 1.275 mm, is greater in T. astensis ), a smaller umbilical callus (see Fig. 19 ) and a more widely open umbilicus. We have found a young operculated specimen of T. anistratenkorum sp. nov. and a loose operculum, referable to this species; their characters are peculiar of species belonging in the genus Tectonatica . These opercula resemble that of T. tectula (Fig. 25.6−9), but are readily distinguished by the greater thickness, the less convex inner surface, with a less protruding nucleus, and the wider central callus, tongue-shaped (bean-shaped in T. tectula ) and more protrusive abapically. The identical teleoconch shape and very similar opercula confirm that T. anistratenkorum sp. nov. and T. tectula are closely related species.

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

Figures

FIGURES 12–19. FIGURE 12. Relationship between the spire height and the shell height for species of Polinices Monfort, 1810 studied herein. FIGURE 13. Relationship between the aperture width and the aperture height for species of Cochlis Röding, 1798 studied herein. FIGURE 14. Relationship between the aperture width and the aperture height for species of Payraudeautia Bucquoy, Dautzenberg & Dolfuss, 1883 studied herein. FIGURE 15. Relationship between the aperture width and the maximum diameter for species of Payraudeautia Bucquoy, Dautzenberg & Dolfuss, 1883 studied herein. FIGURE 16. Relationship between the umbilicus width and the maximum diameter for species of Euspira Agassiz in J. Sowerby, 1837 studied herein. FIGURE 17. Relationship between the umbilicus width and the maximum diameter for species of Payraudeautia Bucquoy, Dautzenberg & Dolfuss, 1883 studied herein. FIGURE 18. Relationship between the width of the umbilical callus and the maximum diameter for species of Cochlis Röding, 1798 studied herein. FIGURE 19. Relationship between the width of the umbilical callus and the maximum diameter for species of Tectonatica Sacco, 1890 studied herein.