Mangelia pseudorugulosa, 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 : 333-334

publication ID	https://doi.org/ 10.4202/app.00158.2015
persistent identifier	https://treatment.plazi.org/id/A8608798-FF82-FFB2-1CDC-76ABFB6F459C
treatment provided by	Felipe
scientific name	Mangelia pseudorugulosa
status	sp. nov.

Treatment

Mangelia pseudorugulosa View in CoL sp. nov.

Figs. 3C View Fig , 4D View Fig , 5E View Fig ; SOM 1: fig. 3C, SOM 2.

Etymology: From Greek pseudo, false, and Latin ruga, wrinkle; in reference to affinities with Mangelia rugulosa ( Philippi, 1844) .

Type material: Holotype, MGGC-24509 , adult, well-preserved shell, outer lip slightly broken . Paratypes, MGGC-24510 /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.— Seventy-two specimens, of which sixty-two topotypes from Varovtsi: IGS-NANU-B-I-4-15/2015 (12 shs), MNHN.F.A53761 (10 shs), MSNG-58189 (10 shs), MGPT-PU135046 (10 shs), MZB-32056 (10 shs), NHMW-2015 /0404/0003 (10 shs) and three topotypes from Velyka Levada, in batch ZISP-62075 (10 shs) .

Diagnosis.—A small Mangelia species (shell lengthm 5.3 mm, sd 0.6 mm; shell widthm 2.3 mm, sd 0.2 mm), characterised by a multispiral protoconch (lengthm 0.52 mm, sd 0.04 mm; widthm 0.51 mm, sd 0.03 mm), a relatively tall spire (0.37 the shell lengthm, sd 0.02), and an almost straight columellar lip. Teleoconch sculpture of apically well rounded and thin ribs (max. 11 on the second whorl) and thin, roundtopped threads densely indented by growth lines.

Description.—Shell small-sized, fusiform; spire slightly turreted (0.37 the shell lengthm, sd 0.02); last whorl rounded in profile. Protoconchm dome-shaped, of 2.1 slightly convex whorls (sd 0.1 wh.); nucleus small, smooth as the remaining whorls except for the final one-third, where 3−4 weak cordlets override low, curved, opisthocline axial riblets; protoconch-teleoconch boundary marked. Teleoconchm of 4.5 whorls (sd 0.5 wh), slightly convex in profile (apical ones tumid), with axial and subdued spiral sculpture; suture slightly undulating. Axial sculpture of rounded, well-spaced, slightly opisthocline ribs (usually 10 on second whorl), extending across the sutures on spiral whorls, until the base on the last whorl. Spiral sculpture of dense, thin elements, more homogeneous on sutural ramp, less uniform below periphery. On spiral whorls two to four thicker threads recognizable. Spiral elements densely indented (and/or beaded) by growth lines, the thinner sometimes truncated. Aperture moderately wide, sub-rectangular (lengthm 2.3 mm, sd 0.2 mm); siphonal canal short. Outer lip thin edged, slightly sigmoid in profile, internally thickened. Anal sinus C-shaped; columellar lip almost straight.

Remarks.— Friedberg (1951), in his review of molluscs from Poland and neighbouring regions, reported Mangelia rugulosa ( Philippi, 1844) from the Miocene deposits of Olesko Ukraine): i.e., the Pidhirtsi Beds of Studencka and Dulai 2010). Bałuk (2003) supported the attribution of the specimens described by Friedberg (1951) to M. rugulosa ( Philippi 1844) and acknowledged the high degree of morphological variability of this taxon. We cannot confirm if the shells reported by these authors are conspecific with M. rugulosa type locality Palermo, Italy; Philippi 1844), that is currently considered a junior synonym of M. unifasciata ( Deshayes, 1835) , a morphologically variable Atlantic and Mediterranean species (see Tucker 2004; WoRMs 2014). However, it is possible to compare the Varovtsi shells with M. unifasciata shells from the Mediterranean (SOM 1: fig. 4B− D, SOM 2).

Qualitative evaluation of some the morphological features of the species described by Philippi such as: (i) sub-rectangular aperture, (ii) short siphonal canal, (iii) thickening of the internal lip and its morphology, and (iv) teleoconch and protoconch shape, suggest a close affinity with M. pseudorugulosa sp. nov. (e.g., SOM 1: fig. 4B− D vs. Fig. 5E View Fig ). Furthermore, statistical analyses performed on a set of M. unifasciata specimens from the Mediterranean and the type material of M. pseudorugulosa highlight that there is no significant difference between the two species with regard to all measured protoconch features, number of teleoconch whorls and shell length ( Fig. 2 View Fig , Table 1, SOM 3). On the other hand, quantitative comparison supports a separation of the two taxa; the new species presents: (i) a narrower and shorter last whorl at comparable number of teleoconch whorls (e.g., widthm 2.3 vs. 2.5, p = 0.017); (ii) a greater number of ribs and fewer spiral elements (e.g., ribsm on second whorl 10.3 vs. 9.5; p << 0.01); and (iii) a shorter aperture (lengthm 2.3 vs. 2.9, p << 0.01; for further details see Fig. 2 View Fig , Table 1, SOM 3). In addition, M. rugulosa morphotype (SOM 1: fig. 4C) possesses flatter spiral whorls and finer spiral sculpture. The analyses performed on M. unifasciata also suggested a higher coefficient of variation for most of the parameters considered here, supporting the high morphological variability already documented for this species (SOM 3). Lastly, one allied morphotype originally separated (i.e., morphotype 12 in SOM 2) on the basis of: (i) the thinner and more uniform spiral sculpture, (ii) the slender spire, (iii) the wider aperture, and (iv) the thin and smooth inside outer lip; overlapped with M. pseudorugulosa in all measured shell parameters ( Fig. 2 View Fig ; Table 1, SOM 2, 3). Hence, we now consider it to fit within the intraspecific variablilty of the species (compare Fig. 5E View Fig vs. SOM 1: fig. 4F).