Procardium avisanense ( Fontannes, 1879 )

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 : 737-740

Procardium avisanense ( Fontannes, 1879)

Figs. 5 , 6 .

1878 Cardium avisanense ; Fontannes 1878: 499, 502 (nomen nudum).

1879 Cardium avisanense sp. nov.; Fontannes 1879: 44.

1903 Cardium hians var. recta ; Dollfus et al. 1903: 44, pl. 16: 4–6.

1912 Cardium (Ringicardium) hians var. recta Dollfus, Cotter, and Gomes, 1903 ; Cossmann and Peyrot 1912: pl. 21, figs. 3–5.

1950 Ringicardium avisanense ( Fontannes, 1879) ; Magne 1950: 124.

Material. —RGM.794104, one shell, one valve, 16 fragments, RGM.794106 (van Nieulande collection), three shells, three valves; from Tortonian (Miocene), Cacela Velha Portugal. RGM.794107 (Visser collection), one valve, some fragments, RGM.794108 (Visser collection), one valve, one fragment; from Serravallian (Miocene), Salles “l’Argileyre”, France. PH 19296, four valves from from Serravallian (Miocene), Salles “Le Minoy”, France. PH 20376, two shells, four valves from Tortonian (Miocene), Cacela Velha, Portugal. PH 20377, three shells, seven valves from Tortonian (Miocene), Fábrica/ Cacela Velha, Portugal. JJTP 4860, three fragments from Tortonian (Miocene), Lacem, Portugal.

Description.— Shell rather large (L up to 85 mm), slightly longer than high, almost equilateral, relatively thin, inflated, moderately gaping posteriorly. Umbo prosogyrate. Anterior and ventral margins rounded, posterior margin truncated and nearly straight. Shell bearing 15–19 primary radial ribs, on anterior half each interspace with a weakly defined, rather broad secondary riblet. Median primary ribs rather well delimited, broad, low rounded and about as wide as interspaces. Anterior ribs prominent with conical-rounded, ventrally hollow scales, placed on rib top. Cross-section of anterior and median ribs trapezium-shaped, with a radial groove on rib tops. Ribs on postero-medial slope strongly asymmetrical in cross section, ultimately flattened posteriorly, with sculpture on posterior rib flanks gradually developing into pointed, posteriorly directed spines. Rib impressions clearly visible from within. Hinge plate rather narrow and slightly sinuous, hinge angle very large. Hinge and ligament: as for genus. Lunule shallowly excavate, dorsal margin slightly raised anterior of umbo.

Remarks. —The original record of Cardium avisanense is from the Miocene of the Rhone Valley, southern France ( Fontannes 1879: 44). The shell shape was described as “généralement un peu plus large que haute, légèrement oblique et inéquilatérale, globuleuse, largement arrondie en avant, subtronquée et comprimée en arrière”, while the radial sculpture was said to consist of 16–18 ribs, “assez élevées, presque arrondies dans la moitié supérieure, subquadrangulaires en avant et vers le bord palléal, divisées en deux par une strie profonde au milieu de laquelle se dressent, à des intervalles assez rapprochés et peu réguliers, de petites écailles”, with a poorly distinct rib sometimes present in the interspaces.

The species was again discussed by Fontannes (1882), while dealing with C. hians from the Pliocene of the Rhone Valley, remarking the separation of the Miocene species C. avisanense from the Pliocene one.

No precise locality was given in the original description, but the species was said to occur in marly-sandy deposits cropping out in the area of Mont Luberon, at Visan and Cucuron together with Pecten vindascinus Fontannes, 1878 , up to the marly deposits with Ancillaria glandiformis Lamarck, 1810 at Cabrières d’Aiguës. From Cucuron and Cabrières d’Aiguës, the species had been reported, as a nomen nudum, by Fontannes (1878). Based on the original indications and on literature data on the stratigraphy of the Mont Luberon area ( Demarcq 1960; Courme-Rault and Dubar 2011), the original records of C. avisanense were from Tortonian deposits.

Fontannes (1879: 45) noted several differences between C. avisanense and C. hians : “Elle [ C. avisanense ] en diffère par un contour palléal moins oblique, plus largement arrondi, par un crochet moins porté en avant, par un côté postérieur plus brusquement tronqué, laissant probablement un écartement beaucoup moins accusé que dans le type subapennin; les côtes sont moins élevées, plus larges, plus arrondies de chaque côté du sillon; celui-ci est plus étroit, moins profond et les épines sont notablement plus petites”.

The type material of C. avisanense was not located, but the careful description and comparison with C. hians by Fontannes (1879) leave no doubts about the identity of this species, which was studied on material from the late Miocene of the Algarve Basin, southern Portugal ( Figs. 5 , 6A, B, E ) and from the Serravallian of the Aquitaine Basin Salles, Le Minoy) ( Fig. 6C, D ). The Portuguese material is fromCacela(nowCacelaVelha)andfromthenearbylocality of Fabrica, where the richly fossiliferous Cacela Formation, of Tortonian–Messinian age ( Santos and Mayoral 2007; Pais et al. 2000; Studencka and Zieliński 2013) crops out. The poorly preserved shell from this formation, illustrated by Studencka and Zieliński (2013: fig. 4E–G) as C. indicum , can be referred to Procardium avisanense .

As remarked in the original description, P. avisanense is markedly similar to P. diluvianum . Both species share relatively wide radial ribs, convex in cross-section, well delimited, bearing a distinct median groove, from which conical scales rise, as well as poorly distinct secondary riblets ( Table 2; Fig. 16F, G ). The distinctive characters of P. avisanense from P. diluvianum are: (i) lower number of ribs 15–19); (ii) smaller size (L up to 85 mm); (iii) less oblique and less inequilateral shape; (iv) ventral margin more regularly convex, not or only weakly expanded posteroventrally. Fontannes (1879) remarked further differences from C. hians , namely a sharper posterior truncation and less anterior umbo. However, in both species the sharpness of the posterior truncation is rather variable and the umbo is practically subcentral. More properly, in P. avisanense the anterior side is slightly larger and more convex than in P. hians , giving the impression of a less anterior umbo. The maximum size is slightly exceeding 80 mm, clearly smaller than P. diluvianum ( Table 2).

A few specimens from the Tortonian of Cacela have particularly straight ribs, with slightly narrower interspaces Fig. 5D, E ). The shell is more inflated and with a narrower posterior gape, while the shape is more equilateral, largely lacking the typical obliquity of the genus. The rib number

(16–17) is within the range of the other specimens from the same locality. At first, these shell characters seem to point to a distinct species, corresponding to Cardium hians var. recta Dollfus, Cotter, and Gomes, 1903 , shortly described “Nous proposons pour les exemplaires figurés la variété recta , largeur 90 mm., hauteur 80. Les côtes sont assez serrées, presque droites, la forme générale moins brièvement tronquée en avant” and nicely illustrated from the Tortonian of Cacela ( Dollfus et al. 1903: 44, pl. 16: 4–6). Probably, the “straight” ribs suggested the specific attribute rectum (= straight, Latin). However, these specimens seem to fall within the variability of P. avisanense , considering that other specimens occur ( Fig. 5F ), which are intermediate in shape and sculpture between the “typical” form with oblique ribs and the specimens matching C. hians var. recta . After all, similar variations also occur in P. diluvianum ( Fig. 3D, G ). Cardium hians var. recta is therefore considered a synonym of P. avisanense , as also proposed by Magne (1950). The records of C. hians var. recta from the Tortonian of Cacela by Chavan (1940) are deemed to be based on P. avisanense .

The specimens from the Serravallian of the Aquitaine Basin ( Fig. 6C, D ) do not differ significantly from the Tortonian ones. It is also worth noting that these specimens show a certain variability in shape and radial ribbing, paralleling to some extent that of the Tortonian material. Cardium (Ringicardium) hians and C. hians var. recta reported by Cossmann and Peyrot (1912: p. 110, pl. 21: 3–5) from Salles are referred to P. avisanense .

Dollfus et al. (1903) mentioned the occurrence at Cacela of large fragments with wide radial interspaces and secondary riblets, together with fragments with long, sharp spines. These shell characters point to a distinct species, misidentified as the “typical” form of “ C. hians ”, namely Procardium kunstleri (Cossmann and Peyrot, 1912) , which does occur in the Tortonian of Cacela. Also the records of C. (Ringicardium) hians mut. recta by Zbyszewski (1957: 135, pl. 5: 40, 41) from the Burdigalian of Portugal, based on internal moulds, point to a distinct species with secondary riblets, corresponding to P. kunstleri or to a similar species. For this reason, the wide distribution in Portugal reported by Dollfus et al. (1903), ranging from the Burdigalian to the Tortonian, is considered doubtful and in need of confirmation.

The record of C. hians from the Tortonian of Tuscany, northern Italy by Tavani and Tongiorgi (1963: 25, pl. 25: 10, 11), based on internal moulds, may represent P. avisanense or a closely similar species with convex, grooved radial ribs, but a clear identification is prevented by the poor preservation. Another Tortonian record from northern Italy ( Venzo and Pelosio 1963: 174, pl. 25: 15), also based on internal moulds, may refer to a distinct Procardium species, markedly oblique in shape and with 16–17 convex ribs, probably grooved.

Stratigraphic and geographic range.— Procardium avisanense is known from the Serrravallian of the Aquitaine Basin and the Tortonian of the southern Rhone Valley and Algarve Basin, thus including the Franco-Iberian Atlantic coast and the Western Mediterranean. A wider, late Miocene distribution in the Mediterranean is possible .

Figures

Fig. 5. Cardiid bivalve Procardium avisanense (Fontannes, 1879) from Tortonian (Miocene) of Portugal, Cacela Velha (A, D, E) and Fabrica (B, C, F). A. RGM.794106.a (van Nieulande collection), internal (A1), external (A2), and umbonal (A3) views. B. PH 20377, internal (B1) and external (B2) views. C. PH 20377, umbonal view. D. RGM.794104.a, internal (D1) and external (D2) views. E. RGM.794104.b, external (E1) and umbonal (E2) views. F. PH 20377, external (F1) and internal (F2) views. Scale bar 50 mm.

Fig. 6. Cardiid bivalve Procardium avisanense (Fontannes, 1879) from Tortonian (Miocene) of Cacela Velha, Portugal (A, B, E) and Serravallian (Miocene) of France, Salles, “Le Minoy”(C) and “l’Argileyre” (D). A. PH 20376, external view. B. PH 20376, external (B1) and internal (B2) views. C. PH 19296, internal (C1) and external (C2) views. D. RGM.794107.a, internal (D1) and external (D2) views. E. RGM.794104.c, detail of anterior sculpture. Scale bars: A–D, 50 mm; E, 10 mm.

Fig. 16. Comparative rib cross-sections and rib sculpture for species of Procardium. Schematic drawings based on the third/fourth rib anterior to the midline, close to the margin of an adult shell. A. P. magnei sp. nov. B. P. jansseni sp. nov. (upper part of rib sculpure reconstructed). C. P. danubianum (rib sculpture undefined). D. P. kunstleri. E. P. aff. kunstleri. F. P. avisanense. G. P. diluvianum. H. P. indicum. Median rib, showing radial groove on rib top (H2). Note presence of microscopic granulations (white arrow) and secondary riblet in interspace (black arrow). Scale bar 5 mm.

Fig. 3. Cardiid bivalve Procardium diluvianum (Lamarck, 1819). A. Syntype of Cardium hians Brocchi, 1814, MSNM i13317, Pliocene, northern Italy (photo Giorgio Teruzzi); external (A1) and umbonal (A2) views. B. Holotype of Cardium diluvianum Lamarck, 1819, MNHN.F.A50147, Pliocene, surroundings of Siena, Italy; external view (photo Jacques Mouchart, http://coldb.mnhn.fr/catalognumber/mnhn/f/a50147). C. MPUR no registration number (unnumbered Cerulli Irelli collection), Early Pleistocene, Farnesina, Italy; external view. D. RGM.794093 (van Nieulande collection), Zanclean (Pliocene), Bonares, Spain; external view. E. RGM.48582.a, Piacenzian (Pliocene), Castell’Arquato, Italy; umbonal view. F. MRSN BS.131.03.001, Pliocene, Asti Hills, Italy; external view. G. RGM.48583, Piacenzian (Pliocene), Castell’Arquato, Italy; external view. Scale bar 50 mm.