Sinum affinis ( 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 : 187-188

Sinum affinis ( Eichwald, 1830)

(Fig. 33.1−4)

Sigaretus affinis Eichwald, 1830: p. 215 ; Eichwald 1840, p. 8; Eichwald 1851, p. 124, pl. 11, fig. 1; Eichwald 1853, p. 257; Eichwald 1859, pl. 11, fig. 1a, b.

Sigaretus haliotoïdeus (non Linnaeus, 1758): Du Bois de Montpéreux 1831, p. 43, pl. 3, figs 47, 48.

Sigaretus striatus (non de Serres, 1829): Pusch 1837, p. 93, pl. 9, fig. 6a, b.

? Sigaretus affinis: Laskarev 1914, p. 645 .

? Sigaretus striatus (non de Serres, 1829): Friedberg 1923, p. 423, pl. 25, fig. 10.

Type material. Sigaretus affinis Eichwald, 1830 , lectotype (designated herein): the unique syntype presently existing in ZISP and figured herein (Fig. 33.1a–e), ZISP 1/62208, height 9 mm, Zhukivtsi, Ukraine (see remarks below).

Type locality. Zhukivtsi , Ukraine .

Type stage. Middle Miocene (Upper Badenian) .

Material examined. Varovtsi: MZB 50510 (1 shell, Fig. 33.2a–b); MZB 50521 (1 shell, Fig. 33.3a–b); MPUM 11757 (1 broken shell, Fig. 33.4a–c); BD 177 (1 shell).

Dimensions. Only 1 shell measured (MZB 50521, Fig. 33.2a–b). DHW = 0.097 mm; PD = 0.910; H = 12.74 mm; D = 20.02 mm; SH = 2.41 mm: AH = 10.33 mm; AW = 13.82 mm; IS = 35°; SA = 143°. DHW and PD measured also for the shell MPUM 11757 (Fig. 33.4a–c): 0.097 and 0.910, respectively.

Description. Protoconch small, low-turbiniform, of 2.80 rather convex whorls, tip very small; protoconch I apparently smooth, protoconch II with first half-whorl sculptured with even, widely spaced axial riblets, which are replaced by obtuse, even spiral cordlets on subsequent half whorl; cordlets gradually vanishing toward end of protoconch. Teleoconch auriculate, depressed, wider than high, rather thin. Spire broadly dome-shaped, depressed, whorls slightly convex. Suture adpressed. Last whorl lenticular, moderately depressed, quickly expanding toward aperture. Subsutural shelf indistinct; narrowly rounded periphery nearly at midline. Aperture large, broadly oval, rather strongly prosocline, wider than high. Parietal callus thin, adapically concave in outline, narrowing abapically, extended to cover the small and narrow umbilical area. Outer lip arched and thin; basal lip semicircular. Inner lip round-edged, with narrow, flat callus sloping inward, reflected toward the umbilical area and merging into the parietal callus. Umbilicus absent. Funicle and umbilical callus absent. Basal fasciole indistinct. Surface sculptured by quite uniform flat-topped spiral cords, thinner subsuturally, occasionally with intervening threads or incised by spiral furrow; interspaces shallow and flat-bottomed, as wide as cords. Base with finer cordlets. Fine and dense growth lines occur throughout. One specimen retains remnants of uniform, pale brown background apparently without any colour pattern.

Remarks. The nomenclatural history of this species is very complex. Eichwald (1830) proposed the new species Sigaretus affinis on the basis of middle Miocene material from Shukowze (= Zhukivtsi), Ukraine. He noted (p. 215) a striking resemblance to Sigaretus haliotoïdeus ( Linnaeus, 1758) , “ der dem Sig. haliotideus auffallend gleicht ”, but he regarded the two species as distinct. A year later, Du Bois de Montpéreux (1831, p. 43) assigned to S. haliotoïdeus a specimen from Szuskowce (= Shushkivtsi), a locality about 10 km from Zhukivtsi, and included Eichwald’s species in the synonymy of S. haliotoïdeus . He also gave a good description and figures of the shell ( Du Bois de Montpéreux 1831: pl. 3, figs 47, 48). Pusch (1837, p. 93) identified the specimens from Krzeminiec (= Kremenets) and Zuckowce (= Zhukivtsi) as Sigaretus striatus , and included in the synonymy of this species the Sigaretus species dealt with by Eichwald (1830) and Du Bois de Montpéreux (1831). He refined the description of S. haliotoïdeus published by Du Bois de Montpéreux (1831, p. 43, pl. 3, figs 47, 48), and illustrated a shell ( Pusch 1837, pl. 9, fig. 6), without specifying the place of collecting, since in the explanation to the plate he indicated only “ Tertiär ” ( Pusch 1837, p. 216). Eichwald (1840, p. 8) reaffirmed the validity of his species stating that “ Mein Sigaretus affinis ist wirklich neu und nicht Sig. striatus M. Serr. ” [My Sigaretus affinis is really new and not Sig. striatus M. Serr. ] and that his diagnosis of the species was sufficient for separation. Finally, Eichwald (1853, p. 257) published an exhaustive description and later also a good figure ( Eichwald 1859, pl. 11, fig. 1) of a specimen of S. affinis from Zhukivtsi. We have obtained a good quality photograph of a shell from Eichwald’s collection housed in the Zoological Institute, St. Petersburg ( Russia), and of the two manuscript labels accompanying this shell. According to Boris Sirenko (pers. comm.), it is not certain whether this shell is Eichwald’s type. However, two notes can be made: 1) on one label (Fig. 33.1d), the script ‘ Sigaretus affinis Eichw., Zukowce (688)’ qualifies the specimen as a topotype, thus a relevant one; 2) the other label (Fig. 33.1e) states ‘ Sigaretus affinis m, Zukowce’. We think that the letter m following affinis could be a short for the Latin word mihi. Should this be correct, this label would have been written personally by Eichwald and the shell be a syntype. Other inquiries about the location of Eichwald’s type material gave negative results. In these circumstances, it seems advisable to designate the considered syntype as the lectotype of Sigaretus affinis (ZISP 1/62208) in order to clarify and fix the characters of this species (ICZN 1999, Article 74 and Recommendation 74D of the Code).

The Recent, Indo-Pacific species Sinum haliotoideum ( Linnaeus, 1758) (Fig. 33.5, 33.6) somewhat resembles the present species, but differs from it in having: 1) protoconch II sculptured after the first half-whorl with even, dense subsutural riblets,with faint threads located in the middle part of the last half-whorl (obtuse, even spiral cordlets, gradually vanishing toward the end of the protoconch in S. affinis ); 2) a more flattened teleoconch; and 3) very different ornamentation, consisting of fine growth lines crossed by closely spaced, rather even spiral bands devoid of longitudinal furrows.

The middle Miocene to Pliocene European species Sinum striatum (Fig. 33.7, 33.8) appears to be the most similar species, but it differs from S. affinis in that it attains a larger size, has a flatter shell and a differently sculptured protoconch (rows of uneven, elongated microscopic granules instead of axial wrinkles and spiral cordlets), protoconch with a smaller diameter, at a size of 0.582 mm.

The Italian Pliocene species Sinum perregulare (Fig. 33.9, 33.10) is also similar but is readily distinguished from S. affinis by having: 1) a differently sculptured protoconch (spiral threads), with a greater diameter (averages 1.347 mm and 0.897 mm, respectively) and greater diameter of the first half-whorl, almost twice the size (averages 0.186 mm and 0.097 mm, respectively); 2) a teleoconch with spiral ribbons and intervening threads; and 3) a smaller overall size.

The Oligocene to early Miocene northeastern Atlantic and proto-Mediterranean species Sinum patulum (Grateloup, 1847) (Figs 33.11, 33.12) is relatively similar, but differs from S. affinis in having a more conical shell and a sculpture of ribbons with threads or cordlets in the interspaces.

Distribution. Middle Miocene: Central Paratethys (upper Badenian) in Ukraine ( Eichwald 1830 and this paper).