Procardium danubianum ( Mayer, 1866 )

Poorten, Jan Johan Ter & Perna, Rafael La, 2017, The West African enigma: Systematics, evolution, and palaeobiogeography of cardiid bivalve Procardium, Acta Palaeontologica Polonica 62 (4), pp. 729-757 : 745-749

publication ID	https://doi.org/ 10.4202/app.00363.2017
persistent identifier	https://treatment.plazi.org/id/03F3E045-FFD2-574A-FF6D-52DE5904F08D
treatment provided by	Felipe
scientific name	Procardium danubianum ( Mayer, 1866 )
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Procardium danubianum ( Mayer, 1866) View in CoL

Fig. 11 View Fig .

1862 Cardium hians Brocchi, 1814 View in CoL ; Hörnes 1862: 181–182, pl. 26:

1–5. 1866 Cardium danubianum View in CoL sp. nov.; Mayer 1866: 71. 1956 Cardium (Ringicardium) hians danubianum Mayer, 1866 View in CoL ; Sieber

1956: 216, pl. 3: 11a, b. 2003 Cardium (Bucardium) ringens danubianum Mayer, 1866 ; Schultz

2003: 519, pl. 75: 2a, b; pl. 76: 9.

Material. — Syntypes of Cardium danubianum Mayer, 1866 : NHMW 1853.XVI.44 (lectotype selected herein), 1 shell; NHMW 1853.XVI.43, 1 shell; NHMW 1853.XVI.41, one valve; from middle–late Badenian (Miocene), Enzesfeld, Austria .

Description.— Shell large (L up to 130 mm), longer than high, weakly inequilateral, relatively thin, inflated, widely gaping posteriorly. Umbo prosogyrate. Anterior and ventral margins rounded, posterior margin truncated and nearly straight. Shell bearing 16–17 primary radial ribs, on anterior half each interspace with a weakly defined, rather broad secondary riblet. Median primary ribs not well delimited, rounded triangular and about 3–4 times as small as interspaces. Anterior ribs prominent, nature of scales undefined (largely broken off), placed on rib top. Cross-section of anterior and median ribs rounded-triangular. Ribs on postero-medial slope asymmetrical in cross section, ultimately flattened posteriorly, with sculpture on posterior rib flanks gradually developing into pointed, posteriorly directed spines. Poorly defined microscopic granulations present on parts of interspaces of anterior half of shell. Hinge and interior undefined (hidden in matrix). Lunule not well defined, dorsal margin raised anterior of umbo.

Remarks. —The species reported by Hörnes (1862: 181– 182, pl. 26: 1–5) as Cardium hians Brocchi, 1814 from the Miocene of Austria was recognized as a distinct species by Mayer (1866: 71), who proposed for it C. danubianum . The name was made available by reference to Hörnes (1862) ( ICZN 1999: art. 12.1), so that the material illustrated by Hörnes (1862) should be considered the type material of C. danubianum . It consists of two articulated shells (NHMW 1853.X.44, Fig. 11A, B View Fig ) from Enzesfeld. The larger specimen (NHMW 1853.XVI.44, Fig. 11A View Fig ) is here selected as lectotype ( ICZN 1999: art. 74.1), the remaining one becoming paralectotype (NHMW 1853.XVI.43, Fig. 11B View Fig ).

Both type specimens were also illustrated by Schultz (2003: 519, pl. 75: 2a, b; pl. 76: 9). Apparently, the drawing of right and left hinges reported by Sieber (1956: pl. 3: 11a, b) is from the lectotype, whose valves are strongly shifted, showing in part their poorly preserved hinge. However, Sieber’s illustration seems to be based more on reconstruction than on their actual state of preservation.

The internal mould of a complete shell reported by Schaffer (1910: 66, pl. 30: 5, 6) as Ringicardium hians var. danubiana from Eggenburg is markedly different in shape and sculpture from the type material, appearing more similar to some internal moulds from the Serravallian of Turkey (e.g., Fig. 10E, G View Fig ). Another internal mould from Eggenburg (NHMW 1869.III.16) seems similar to P. danubianum , but no clear identification is possible.

The type locality Enzesfeld, south-west of Vienna, is one of the fossiliferous localities in the Vienna Basin of middle–late Badenian age (late Langhian–middle Serravallian) ( Strauss et al. 2006; Paulissen et al. 2011). The Eggenburg deposits, cropping out north-west of Vienna belong to the North Alpine Foreland Basin and are late Eggenburgian (early Burdigalian) in age ( Mandic and Steininger 2003).

According to Mayer (1866), C. danubianum differs from “ C. darwini ” (i.e., the Miocene species misidentified by Mayer as the living P. indicum , representing P. magnei sp. nov., described below) by its larger umbo and its broader, lower and more closely set ribs, with secondary riblets in the interspaces. Indeed, these are diagnostic features of C. danubianum and “ C. darwini ”. However, Mayer’s (1866: 71) differential diagnosis was most probably based on more than one species, as he referred to C. danubianum specimens from the area of Ulm, southern Germany and Bern, Switzerland, preserved as internal moulds (“Ce type se retrouve aux environs d’Ulm et de Berne, et on le reconnaît facilement même à l’état de moule”). Evidently, his material originated from the Swiss and German Upper Marine Molasse, in the North Alpine Foreland Basin, of Eggenburgian–Ottnangian (early–middle Burdigalian) age ( Heckeberg et al. 2010; Pippèrr 2011; Pfister et al. 2011), but the Procardium specimens known from this formation seem closer to P. kunstleri , as discussed above.

almost equidimensional as P. indicum , P. diluvianum , and P. avisanense , and with a particularly large umbo.

Sacco (1899: 48, pl. 10: 15) reported C. (Ringicardium) cf. danubianum from Albugnano, “Helvetian” locality in the Turin Hills, northern Italy, now referred to the Langhian ( Zunino and Pavia 2009). It is a poorly preserved valve, ca. 75 mm in length, somewhat oblique and with a large, prominent umbo ( Fig. 12A View Fig ). It has 12 or 13 main ribs, and well distinct, rather strong secondary riblets. Because of its poor condition, it was not possible to ascertain the occurrence of granulations. It is possibly a distinct species, apparently similar to P. danubianum . The same author described C. (Ringicardium) hians var. dertogigantea ( Sacco 1899: 48, pl. 10: 14), from the Tortonian of Stazzano, Turin Hills, on a shell fragment showing the anteriormost median rib, square in cross section, and the first, asymmetrical anterior rib. Evidently, the poor preservation prevents from identification and var. dertogigantea is considered a nomen dubium.

The record of Cardium hians danubiana by Mandic et al. (2004) from the Burdigalian of southern Turkey, herein reported under P. kunstleri , seems to be based on P. danubianum , but its identification cannot be confirmed because of the poor preservation.

Stratigraphic and geographic range.— Procardium danubianum is known from the late Langhian–middle Serravallian of Austria (Central Paratethys).

The lectotype, ca 130 mm in length, has 16 ribs in the right valve; the left valve is fragmentary. The median ribs are moderately strong and roughly triangular in cross section. A fairly distinct medial secondary riblet is present in the wide interspaces ( Fig. 11A View Fig 4 View Fig ). Scales on the anterior and median ribs are mostly abraded and apparently funnel-shaped ( Fig. 16C View Fig ), while the posterior spines are mostly lost. The paralectotype, ca. 70 mm long, has the same type of sculpture as the lectotype, with 16 main ribs in the right valve; the left valve is broken. The specimen is almost equidimensional, suggesting marked ontogenetic changes in shape. In both specimens, the shell surface is crossed by particularly well distinct growth striae. A microsculpture is present in the radial interspaces: it consists of indistinct granulations, mostly located on the growth striae, though not regularly aligned on them ( Fig. 11B View Fig 3 View Fig ).

Procardium danubianum is particularly similar to P. kunstleri in sculpture: both species share a relatively low number of ribs, not exceeding 17, which are narrow and roughly triangular in shape, with wide interspaces and well distinct secondary riblets. Some similarities are also seen in shape, both species being somewhat elongate, instead of Procardium jansseni sp. nov.

Figs. 13 View Fig , 14 View Fig .

1925 Cardium (Ringicardium) danubianum Mayer View in CoL ; Kautsky 1925: 36. 1950 Cardium (Ringicardium) hians Brocchi, 1814 View in CoL ; Heering 1950: 32. 1972 Cardium (Ringicardium) sp.; Nordsieck 1972: 38, pl. 8: 59.

1975 Bucardium sp. ; Bosch et al. 1975: 82, pl. 12: 2.

1984 Cardium (Bucardium) sp.; Janssen 1984: 82, pl. 31: 3–5.

1994 Cardium (Bucardium) sp.; Moths 1994: 67, figs. 1–6.

1999 Cardium (Bucardium) sp.; Wienrich 1999: 240, pl. 57: 3a, b.

2010 Bucardium sp. ; Moths et al. 2010: 21, fig. 13, pl. 7: 6, 7.

2016 Bucardium cf. danubianum ( Mayer, 1866) ; Stein et al. 2016: 19, pl. 7: 5.

Etymology: After Arie W. Janssen, former curator of Cainozoic Mollusca at the National Museum of Geology and Mineralogy (now Naturalis Biodiversity Center, Leiden, The Netherlands), in recognition of his extensive contributions to our knowledge of Miocene molluscs of the North Sea Basin.

Type material: Holotype RGM.1309269 (van der Voort collection), top fragment of right valve (26 mm), Paratypes: RGM.225754, fragment of right valve (40 mm), RGM.225755, fragment of right valve (24.5 mm), RGM.225756, two fragments of right valves (largest 34 mm); all from the type locality.

Type horizon: Dark greenish black, variably silty, glauconite sand with many shells. Miste Bed, Breda Formation, lower part of the Aalten Member, Hemmoorian (Langhian), middle Miocene.

Type locality: Miste “Berenschot”, near Winterswijk, province of Gelderland, The Netherlands.

Material. —RGM.794091 (van den Bosch collection), 1 fragment; RGM.1309415, RGM.1309416, RGM. 1309417, RGM.1309418 (all van der Voort collection), 4 fragments; RGM.794092, 3 fragments; RGM.1309991 (ter Poorten collection), 1 fragment, JJTP2071, JJTP2072, 11 fragments; PH 36255, 41 fragments; JV unnumbered specimens,

100 fragments; from Langhian (Miocene), Miste, The Netherlands. RGM.794094 (Rijks Geologische Dienst collection), 3 fragments from Miocene, borehole Beeringen DB15 (B58B0008), De Peel, Beringe, The Netherlands. RGM.794095, Rijks Geologische Dienst collection), 4 fragments from Miocene of De Peel, Baarlo I, The Netherlands. JV unnumbered specimens, 18 fragments from Langhian (Miocene), Werder, Germany.

Diagnosis. —A rather large, inflated Procardium species with 19–24 sharply delimited high triangular radial ribs. Scales on anterior part close-set and also covering the rib flanks. Interspaces very broad with dense and commarginally alligned bands of minute granulations on anterior and median zones.

Description. —Shell large (L up to 95 mm, extrapolated), slightly longer than high (extrapolated), weakly inequilateral, thin shelled, inflated, with a moderately wide posterior gape along whole length of posterior margin. Umbo slightly prosogyrate. Anterior, ventral, and postero-ventral margins rounded; posterior margin weakly rounded and truncated. Shell bearing 19–24 sharply delimited, thin primary radial ribs, on anterior half alternating with a very weakly developed, broad and flattened secondary riblet. On median part, interspaces about 5–6 times wider than primary ribs. Radial ribs tiny and crowded on antero-dorsal slope, thin and rather pointed triangular on anterior and ventral slope, with broadly horseshoe shaped or funnel shaped close-set scales, also covering most of rib flanks and hollow ventrally. Ribs on posterior slope very low saw-tooth shaped with a sharp rib crest, sculptured with pronounced spines, placed on posterior rib flanks, directed posteriorly. Fine commarginal growth lines present in interspaces, combined with well developed, commarginally aligned bands of dense granulations on anterior and median zones. Rib impressions well visible from within. Hinge with nearly horizontally rotated cardinal teeth. Left valve: two cardinal teeth of which the anterior one well defined, posterior one tiny; both teeth connected at their bases, with a deep socket below. Right valve: two similar sized (extrapolated), erect, pointed cardinal teeth, not touching at their bases but separated by a deep socket. Anterior lateral sockets curved, extremely excavated; lateral teeth of both valves thin, blade like. Ligament rather short. Lunule not well defined, dorsal margin slightly raised anterior of umbo.

Remarks. —Fragments of Procardium from the early Miocene of the North Sea Basin, The Netherlands and northern Germany, are common in museum and private collections ( Nordsieck 1972: 38, pl. 8: 59; Bosch et al. 1975: 82, pl. 12: 2; Janssen 1984: 82, pl. 31: 3–5; Moths 1994: figs 1–6; Wienrich 1999: 240, pl. 57: 3a, b; Moths et al. 2010: 21, fig. 13, pl. 7: 6, 7; Stein et al. 2016: 19, pl. 7: 5) as Cardium (Ringicardium) danubianum ( Kautsky 1925: 36) or as C. (Ringicardium) hians ( Heering 1950: 32) in the literature.

Records are mainly from the area of Winterswijk-Miste (province of Gelderland, The Netherlands) and to a lesser extent from the Peel region (bordering Noord-Brabant and Limburg provinces, The Netherlands), but there are also several records from northern Germany (Hemmoor- Basbeck, Itzehoe, Kevelaer, and Werder), all from deposits of Hemmoorian age, late Burdigalian to Langhian in the standard time scale ( Janssen 2001; Gürs and Janssen 2002). The deposits in the area of Winterswijk-Miste most probably are late Hemmoorian (Oxlundian), i.e., Langhian in age (Arie W. Janssen personal communication 2017).

The study material, generally well preserved apart from fragmentation and invariably brownish-gray coloured, is mostly from Winterswijk-Miste, with the addition of few fragments from the coeval deposits at Beeringen (now: Beringe) and Baarlo, both in De Peel region, and Werder in northwestern Germany. The relatively abundant material (over 100 fragments), allowed the shell characters of the new species to be recognized and described. In order to give a realistic impression of a complete valve, a graphic reconstruction is herein given ( Fig. 14 View Fig ), based on a photographic collage of 12 fragments, most of which are illustrated ( Fig. 13 View Fig ), as well as examination of numerous additional fragments.

The shell of P. jansseni sp. nov. is particularly thin and fragile, and the fragmented condition in which this species is found is evidently due to its intrinsic shell fragility and weakness of radial ribs. The largest fragments are mostly from the anterior and posterior regions: in the former, scales are particularly crowded, giving some strength to shell, while the latter have wider and stronger ribs.

Further comments and comparisons are reported under the respective species.

Stratigraphic and geographic range.— Procardium jansseni sp. nov. is only known from the late Burdigalian to Langhian of the southern North Sea Basin.