Parvamussium felsineum (Foresti, 1893)
FORESTI, L. 1893. Enumerazione dei Brachiopodi e dei Molluschi pliocenici dei dintorni de Bologna. Parte II. Bullettino della Società Malacologica Italiana, 18: 185-413. [p. 381]
1896 Amussium [sic] felsineum Foresti, 1893
«Mostra moltissima somiglianza coll' A. duodecimlamellatum; ne è uguale per dimensioni, e com' esso varia nel numero delle coste interne, le quali però sono identiche per la disposizione, per il rigonfiamento terminale e per presentarne alcune intermediarie non complete; diversifica un poco per la forma della conchiglia mostrandosi un poco più rotondata causa l'avere un poco più lungo il diametro antero-posteriore. L' ornamentazione ne è differente; mentre le lamelle trasversali sono molto più rade e perciò in minor numero, sono anche molto meno prominenti, ed invece sono bene apparenti delle filiformi e numerosissime costicine longitudinali che irradiano dall' apice alla periferia e che vengano a tagliare la lamelle concentriche formando, specialmente presso gli apici un elegante reticolato. Il margine cardinale è diritto ed internamente mostra una piccolissima fossetta triangolare pel legamento. Dal punto dove terminano le costicine interne, fino all' estremità del margine, il guscio della conchiglia è sottilissimo, trasparente e minutamente striato. Quanto all' orecchiette non posso nulla precisare, non essendo complete.
Presenta ancora moltissima somiglianza coll' A. cancellatum Smith (1), non tanto per le dimensioni, essendo il vivente molto più grande, ma quanto l' ornamentazione, il margine striato internamente e la disposizione delle costicine interne; quanto alla forma il nostro esemplare ha il diametro umbo-ventrale proporzionatamente più corto; con tutta probabilità da questa forma fossile può essere derivata la forma vivente. Dimensioni — Diametro antero-posteriore 10 millim. Diametro umbo-ventrale 10 ½ millim. Marne argillose — Ponticello in vai di Savena — Coll. Berti, Foresti; raro.» (1) Smith — Zool. Voyag. Challeng. part. XXXV, Rep. Lamellib., pag. 315, tav. XXIII, fig. 8.
LODOVICO FORESTI, 1893
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«Parvamussium shells from the Central Paratethys bearing radial sculpture on the left valve were formerly always identified as P. felsineum. According to the number of internal riblets they certainly belong to at least two species, viz., P. fenestratum (14–24) and P. miopliocenicum (10–12) or P. felsineum (10–12). The latter species was introduced by Foresti (1893, p. 381, 382) on the basis of the Pliocene material found at Ponticello in the Val Savena near Bologna. According to the original description, the fragile shell (up to ca. 10 mm high) is oval in outline (wider than high), with reticulate sculpture: very numerous and easily visible thread-like radial riblets cutting less prominent and more loose commarginal lamellae form elegant reticulae, mainly near the beak. The internal surface bears ten to twelve radial riblets, some times with a few rudimentary interstitial ones, terminating at some distance from the ventral margin. From the end of the internal riblets to the ventral margin, the shell is very thin, transparent and finely striated. Unfortunately, no type material of felsineum was figured by Foresti. Only in formation that both ornamentation and arrangement of internal riblets in felsineum is similar to that in Amussium cancellatum Smith, 1885 may justify the presumption that reticulate sculpture is present on the left valve whilst the right valve is ornamented with closely spaced commarginal lamellae.
The species P. felsineum seems to be scarcely sparsely within the Mediterranean area. It is reported from the Pliocene of Italy (Foresti, 1893; Ruggieri, 1950). Its supposed occurrence in the eastern Middle Miocene Mediterranean is based on Roger’s (1939) record from Syria. Unfortunately, no illustrations of the Mediterranean felsineum were provided. The occurrence of P. felsineum in the Oligocene of the Paratethys was only presumed (Báldi, 1986). A well-documented record apparently begins with the Karpatian (Early Miocene) of Slovenia and Slovakia (Meznerics, 1936; Harzhauser et al., 2011, respectively). The Paratethyan specimens of P. felsineum appear to conform in many important respects to the typical form de scribed from the Pliocene of Italy; although Paratethyan specimens are some what elongated and slightly posteriorly oblique (the type specimens are al most circular in shape, some what wider than high). Their left valves bear a reticulate sculpture produced by intersecting numerous (about 30 at central disc portion) prominent radial ribs and delicate commarginal growth lines in early to medium growth stages, and with prominent commarginal sculpture in late growth stages (while the type specimens show much weaker but more regular reticulate sculpture). Interstitial riblets in side left valves are not observed. There fore, Meznerics (1936, p. 124, 125) proposed the name Amussium (Variamussium) felsineum Foresti var. styriaca for specimens with prominent reticulate sculpture on the left valve. In the Paratethys this morphotype of P. felsineum with strongly radial sculpture is reported from the Lower Miocene clayey deposits (Karpatian) of Slovenia and Slovakia, and from the Mid dle Mio cene (Lower Badenian) of Poland (Meznerics, 1936, pl. 1, figs. 1–6; Harzhauser et al., 2011, fig. 11.1–4; Krach 1957, pl. 1, figs. 1, 18, respec tively). Moreover, the presence of P. felsineum is documented in several outcrops of the Lower Badenian in the north-western Bulgaria (Kojumdgieva, 1969, 86, pl. 2, figs. 3–11) and in the Lower-Middle Miocene of the Vienna Basin in Austria (Deperet and Roman, 1928, pl. 27, figs. 12, 12a, 13, 13a; Schultz, 2001, 162–164, pl. 15, figs. 10, 10a, 11, 11a). The considered morphotype styriaca resembles very closely P. fallax (Korobkov, 1936) wide spread in Upper Eocene strata in Caucasus, Russia and Georgia (Korobkov, 1936, p. 70, 71, pl. 1, figs. 1–13, pl. 2, figs. 1–3; Korobkov, 1954, pl. 73, figs. 3–5), west wards to Hungary (Báldi, 1986, pl. 1, fig. 1). The two species are some what elongated and slightly posteriorly oblique in shape with similar reticulate sculpture visible on the left valve. More over, they have the same shape and number of internal riblets re stricted to the proximal four-fifths of the height and lack of interstitial riblets. In the opinion of the senior author, these morphological shell features suggest that P. felsineum might be a di rect descendent of the Eocene P. fallax.» STUDENCKA, B., V. A. PRYSYAZHNYUK & S.A. LJUL’EVA. 2012. First record of the bivalve species Parvamussium fenestratum (Forbes, 1844) from the Middel Miocene of the Paratethys. Geological Quarterly, 56 (3): 513-528, figs. 1-5. [p. 523]
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Amussium (Variamussium) felsineum Foresti nov. var. styriaca; I. Meznerics, 1936, Die Schlierbildungen des mittelsteirischen Beckens, plate 4, figures 1-6.
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«Remarks: Shell as high as long, low convex, circular in outline, inclined anteriorly, dorsal margin straightened with posterior ear small and anterior ear large and pointed. Right valve exterior with regular, fine, slightly projecting comarginal lirae, left valve exterior with numerous (about 30 at central disc portion) fine ribblets intersected by fine projecting lirae; the number of ribblets increases distally by intercalation; scaly nodes present at lirae/ribblet intersections. Interior with about 12 interior ribs restricted to proximal four fifths of height, the very distal fifth with thinned shell wall.
The presence of radial ribblets on the left valve exterior surface allows a differentiation of this species from P. duodecimlamellatum. In contrast to NW Bulgaria (Kojumdgieva & Strachimirov 1960), no smooth left valves were recorded from the Styrian and Vienna Basins and the identifications of P. duodecimlamellatum in those basins is questionable (Deperet & Roman 1928; Mikuž 1998; Schultz 2001). Because of the prominent left valve sculpture, our specimens correspond to P. felsineum morph. styriaca (Meznerics 1936).
P. felsineum is frequent in the Early Badenian of the Styrian Basin and the northern Slovenia (Meznerics 1936; Mikuž 1998) and in the Early/Middle Badenian of the Vienna Basin in Austria (Depéret & Roman 1928; Schultz 2001) and NW Bulgaria, the Late Badenian of the Carpathian Foredeep in SE Poland (Jakubowski & Musiał 1977) and the Pannonian Basin in NE Hungary (Csepreghy-Meznerics 1960, 1966). Further, the species is present from the Middle Miocene to Pliocene in the Mediterranean Sea and the NE Atlantic. The type locality of Ponticello in the Val de Savena near Bologna in Italy is of Pliocene age.» HARZHAUSER, M., O. MANDIC & J. SCHLÖGL. 2011. A late Burdigalian bathyal mollusc fauna from the Vienna Basin (Slovakia). Geologica Carphatica, 62 (3): 211-231, figs. 1-14. [p. 222, 223]
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