Upper Oligocene (Chattian) brachiopod fauna from the Aquitaine Basin, southwestern France and its paleoenvironmental implications Author Bitner, Maria Aleksandra Author Lozouet, Pierre Author Cahuzac, Bruno text Geodiversitas 2013 2013-09-27 35 3 579 606 journal article 10.5252/g2013n3a418 1638-9395 5381126 Joania peyrerensis n. sp. ( Fig. 7 A-I; Table 7 ) TYPE MATERIAL . — Holotype MNHN .F.A46532: specimen figured in Fig. 7 A-C; paratypes MNHN .F. A46533 , A46534: specimens figured in Fig. 7 D-I. ETYMOLOGY. — Referring to the name of type locality, Peyrère. MATERIAL EXAMINED. — Peyrère: one complete specimen. — Bélus: three complete specimens and one dorsal valve. TYPE HORIZON AND LOCALITY . — Upper Oligocene, Peyrère, Aquitaine Basin, SW France . DIAGNOSIS. — Small, rounded subrectangular Joania with surface ornamented by six to eight distinct ribs; teeth triangular; dorsal septum high, triangular in profile with serrations; tubercles on inner margin of both valves. DESCRIPTION Shell small, not exceeding 3 mm in length, rounded subrectangular in outline with maximum width at mid-valve, weakly biconvex. Shell surface covered with 6 to 8 distinct ribs. Hinge line shorter than maximum width, slightly curved. Anterior commissure rectimarginate. Beak high with distinct beak ridges. Interarea narrow. Foramen large, triangular, hypothyrid flanked by elevated, narrow deltidial plates. Ventral valve interior with plate-like, triangular teeth ( Fig. 7 F-H). Pedicle collar wide, excavate anteriorly, supported by a slender septum that extends beyond mid-valve. On inner surface radial ridges terminating in tubercles ( Fig. 7I ). Dorsal valve interior with narrow but high inner socket ridges. Dental sockets deep. Cardinal process distinct. Septum high, triangular in profile, with 4 serrations. Numerous tubercles on inner margin ( Fig. 7D, E ). Loop not preserved. REMARKS Álvarez et al . (2008) created Joania as a monospecific genus, however, since that time several Argyrotheca species have been transferred into the genus Joania , based mostly on the important diagnostic character – numerous radial ridges terminating anteriorly in tubercles on the inner margin. ffle presence of marginal tubercles in the specimens from the Aquitaine Basin supports their attribution to the genus Joania . In the ornamentation of 6-8 distinct, sharp ribs J. peyrerensis n. sp. can be easily distinguished from other so far described Joania species. ffle shell surface of J. cordata is smooth or covered with almost imperceptible costae ( Logan 1979 ; Bitner 1990 ; Álvarez et al . 2008 ). In addition, both species differ in the nature of the teeth; in J. peyrerensis n. sp. the teeth form a triangular plate, while in J. cordata they are hooked. ffle shell of a Recent Indo-Pacific species J.arguta (Grant, 1983) is also completely smooth without any costae (Bitner 2008; Simon 2010 ). ffle teeth in this species are, similarly like in J. cordata , hooked given off dorsally, thus differing clearly from J. peyrerensis n. sp. ffle studied specimens differ strongly from the Lower Pleistocene species from southern Italy , Joania ageriana , originally described as Argyrotheca ageriana by Taddei Ruggiero (1993) . Joania ageriana is much larger, reaching 7 mm in length, and ornamented by 14 to 18 rounded ribs ( Taddei Ruggiero 1993 , 1994 ) FIG. 7. — Joania peyrerensis n. sp. , Upper Oligocene: A -C , ventral and dorsal views of complete specimen, and enlargement of posterior part to show details of the beak, holotype MNHN.F.A46532, Peyrère; D , E , inner and oblique lateral views of dorsal valve, paratype MNHN.F. A46533 , Bélus; F -I , inner view of ventral valve, enlargement of posterior part ( G ) and details of left tooth ( H ) and enlargement of anterior part ( I ) to show radial ridges terminating anteriorly in tubercules, paratype MNHN.F.A46534, Bélus. All SEM. Scale bars: A, B, D-F, 1 mm; C, G, I, 500 µm; H, 100 µm. TABLE 8. — Measurements (in mm) of Megerlia truncata ( Linnaeus, 1767 ) .

Locality	Length	Width
Peyrère	?6.3	10.1
Peyrère	10.3	–
Peyrère	6.7	9.3

FIG. 8. — Megerlia truncata ( Linnaeus, 1767 ) , Upper Oligocene, Peyrère (MNHN.F. A46535 ), complete specimen in ventral ( A ) and dorsal ( B ) views. Scale bar: 3 mm. Dulai (2010a) attributed a single dorsal valve from the Late Miocene of Italy to Joania aff. falunica (de Morgan, 1915), recognizing in this brachiopod diagnostic characters of the genus. ffle poor material prevents any formal description of a new species.