Bela varovtsiana, Scarponi & Bella & Dell’Angelo & Huntley & Sosso, 2016

Scarponi, Daniele, Bella, Giano Della, Dell’Angelo, Bruno, Huntley, John Warren & Sosso, Maurizio, 2016, Middle Miocene conoidean gastropods from western Ukraine (Paratethys): Integrative taxonomy, palaeoclimatogical and palaeobiogeographical implications, Acta Palaeontologica Polonica 61 (2), pp. 327-344 : 336-337

publication ID	https://doi.org/ 10.4202/app.00158.2015
persistent identifier	https://treatment.plazi.org/id/A8608798-FF8D-FFBF-1C29-75D2FDF0443C
treatment provided by	Felipe
scientific name	Bela varovtsiana
status	sp. nov.

Treatment

Bela varovtsiana View in CoL sp. nov.

Figs. 4F View Fig , 5I− K View Fig , 6A View Fig ; SOM 1: fig. 3E, SOM 2.

Etymology: Named after the type locality (Varovtsi), where it occurs in abundance.

Type material: Holotype, MGGC-24516 adult, well-preserved shell . Paratypes, MGGC-24517 /1–14 from the type locality (SOM 2) .

Type locality: Varovtsi , Ukraine .

Type horizon: Massive, white sandstone of the Pidhirtsi Beds, early Serravallian (~14.0−12.7 Ma).

Material.— One hundred and five topotypes from Varovtsi: IGS-NANU-B-I-18-32/2015 (15 shs), MNHN.F.A53762 (15 shs), MSNG-58190 (15 shs), MGPT-PU135047 (15 shs), MZB-32057 (15 shs), NHMW-2015 /0404/0004 (15 shs), and ZISP-62077 (15 shs) .

Diagnosis.—A small-sized Bela (shell lengthm 4.7 mm, sd 1.0 mm; shell widthm 2.1 mm, sd 0.4 mm), with multispiral protoconch with nodose ribs (lengthm 0.50 mm, sd 0.03 mm; widthm 0.52 mm, sd 0.03 mm), relatively short spire (0.35 shell lengthm, sd 0.02) made of rounded whorls with a poorly-delimited sutural ramp; last whorl inflated; columellar lip straight and siphonal canal almost indistinct. Teleoconch sculpture of closely spaced, well rounded, relatively strong ribs (max. 11 on the second whorl) and a dense pattern of fine, but uneven and beaded threads.

Description.—Shell small-sized, fusiform; spire conical (0.35 shell lengthm, sd 0.02); last whorl slightly rounded. Protoconchm dome-shaped of 2.3 convex whorls (sd 0.2 wh); nucleus small, smooth as the remaining whorls except for the final one-third, where 3−4 faint cordlets override curved axials forming swollen tubercles at the intersections. Protoconch-teleoconch transition with pustules, marked by a sinusigera. Teleoconchm of 3.7 whorls (sd 0.3 wh) convex in profile, with strong axials and subdued spiral sculpture; suture marginated, undulating. Axial sculpture of prominent, rounded ribs (usually 10 on second whorl), thicker on their abapical portions, thinner upward, ending in proximity to the adapical suture. Growth lines dense, evident. Spiral sculpture of fine, relatively uniform threads alternating with thicker threads (usually 4 on second whorl), strengthening around periphery, interspaces of variable size. Spiral elements densely beaded by growth lines; the thinner ones often truncated. Aperture moderately wide, lanceolate (lengthm 2.2 mm, sd 0.4 mm); siphonal canal very short (almost indistinct); outer lip thin, smooth within, convex in profile; anal sinus relatively broad, v-shaped on the sutural ramp. Columellar lip slightly bent.

Remarks.—The combination of small size, rounded shoulder, shell sculpture, morphology of the aperture and position of the anal sinus suggests assignment to the genus Bela and more specifically to the Bela nebula group (see remarks in Scarponi et al. 2014b). Bela varovtsiana is morphologically similar to the recently described Mediterranean Pliocene B. pseudoappeliusi Naldi, Della Bella, and Scarponi, 2013 (SOM 1: fig. 4G, H), particularly in regard to teleoconch features such as: (i) shell dimensions and outline, (ii) number of whorls, (iii) morphology of the aperture and sinuses, and (iv) sculptural pattern of the shell: teleoconch of evident axial ribs overrun by densely beaded threads and protoconch of nodose axials and pustules. Furthermore, a great part of the teleoconch features measured here show a strong overlap between the two species ( Fig. 2 View Fig , SOM 2) with both parametric and non-parametric tests supporting this high morphological homogeneity ( Table 1, SOM 3). However, when compared to B. pseudoappeliusi , it may be noted that B. varovtsiana sp. nov. shows more numerous teleoconch ribs (mean 9.5 vs. 8.7 on second whorl; p <0.01), and less numerous, more spaced spiral elements (mean 4.6 vs. 7.8 on second whorl, p << 0.01; Fig. 2 View Fig , SOM 2). Furthermore, the protoconch of B. varovtsiana is notably smaller with respect to that of B. pseudoappeliusi (e.g., lengthm 0.50 mm vs. 0.63 mm respectively, p << 0.01; for further details see Fig. 2 View Fig , SOM 2); this clear separation is also strongly supported by all relevant tests here employed ( Table 1 and SOM 3).