BULLETIN DH L'INSTITUT ROYAL DHS SCIENCES NATURELLES DE BELGIQUE SCIENCES DE LA TERRE, 70: 75-88. 2000 BULLETIN VAN HET KONINKLIJK BELGISCH INSTITUUT VOOR NATUURWETENSCHAPPEN AARDWETENSCHAPPEN, 70: 75-88, 2000 Phacoiderhynchus, a new middle Famennian rhynchonellid genus from the Anti-Atlas, Morocco, and Phacoiderhynchidae n. fam. by Paul SARTENAER Abstract D ia g n o s is Large-sized, flat, elliptical outline. Ventral sulcus, dorsal Phacoiderhynchus n. gen., type species P. antiatlasicus n. sp., is fold. Costae few, relatively high, strong, starting at some described from the middle (UD III-B to IV-B) Famennian of Ma'ider, southern Morocco: the genus is also probably present in Central distance from the beak. Median costae commonly di­ Morocco. The new genus results from a further restriction of the vided. Dental plates; no septum; no crural plates; divided meaning of the genus Planovatirostrum Sartenaer 1970, and is type hinge plate; simple cardinal process. of Phacoiderhynchidae n. fam. Key-words: Phacoiderhynchus. Phacoiderhynchidae. rhynchonellid. C o m p o s it io n brachiopod, Famennian, Morocco. Phacoiderhynchus n. gen. as sole genus so far. R e m a r k Résumé The flatness of the shell combined with the absence of a septum, the presence of dental plates and of a simple Phacoiderhynchus n. gen., avec P. antiatlasicus n. sp. du Famennien cardinal process, and the absence of crural plates allow moyen (UD Ill-B ¡i IV-B) du Ma'ider. Maroc méridional, comme the separation of the new family from all known families, espèce-type, est décrit; le genre est aussi probablement présent au Maroc Central. Le nouveau genre résulte de l'éclatement du genre in particular from Tetragonorhynchidae Sartenaer, Planovutiroslrum S arthnakr 1970 et est le genre-type de Phacoider­ 1999, which has a bilobate cardinal process, and no dental hynchidae n. tam. plates. Mots-clefs: Phacoiderhynchus. Phacoiderhynchidae, Rhynchonellide, Brachiopode, Famennien. Maroc. Phacoiderhynchus n.gen. This paper is a further step towards the unravelling of the D e r iv a t io n o m i n is Famennian rhynchonellids of Moroccan Anti-Atlas. Spe­ OaKoeidriç, pç, eç (Greek) = lenticular; t o puy^oç cial attention is paid to those occurring with goniatites, (Greek, neuter) = beak. The name draws attention to the because the ammonoid deep water facies zonation is a characteristic lenticular profile of the shell. key element for ascertaining the precise stratigraphical range of new rhynchonellid taxa. In this respect, the T y p e s p e c ie s description of the Jebel el Mrakib section by B e c k e r et Phacoiderhynchus antiatlasicus n.gen., n.sp. al. (1999) is very helpful, because 78 per cent of the specimens of the new species described below come from D ia g n o s t ic f e a t u r e s this locality. Old and recent collections were examined in Large-sized. Strongly costate. Uniplicate. Flatly bicon­ order to describe Phacoiderhynchus n. gen., which is a vex. Elliptical outline. Commissure sharp. Sulcus, fold, stratigraphically restricted genus showing a combination and median costae beginning at some distance from beak. of characters leading to the establishment of a new fa­ Sulcus well marked, shallow, and wide. Fold low and mily. commonly marked by a slight depression. Tongue low, wide, and well defined. Top of tongue always located lower, often considerably lower, than top of shell. Costae Superfamilv RhynchonellaceaG r a y , 1848 in moderate number, wide, and relatively high. Divisions Phacoiderhynchidaen.farn. and intercalations common in median costae. Width ex­ ceeding length considerably. Wide apical angle. Dental T y p e g e n u s plates tortuous and convergent. Relatively small umbonal Phacoiderhynchus n. gen. cavities. Septum and crural plates absent. Divided hinge 76 Paul SARTENAER plate with wide outer plates. Simple cardinal process. stout. Delthyrial cavity wide. Neither septum nor septa- Crura slender, crescent-shaped in their distal part. lium present. Instead of a septum a slight median swelling or even a low crest is present on the valve floor. Dental S p e c i e s a t t r i b u t e d t o t h e g e n u s sockets deep and narrow. Hinge plate divided, of variable Only the type species is attributed to the genus. thickness, but always thin anteriorly. Outer plates wide, Two poorly preserved moulds of pedicle valves (one slightly convex and slightly inclined towards each other, of them figured) of Planovatirostrum sp. described by and extending some distance anteriorly as appendages of Brice & D rot (in B r i c e eta/., 1984, p. 447, pp. 450-451, the crura. Extremely short (0.3 to 0.4 mm in serial trans­ pi. XII, fig. 3) could belong to the new genus, and even to verse sections) and simple cardinal process resting on the its type species, although they have shorter median and hinge plate. No crural bases to speak of. Slender crura lateral costae. In the absence of sufficient material and with Phrygian cap shape in section posteriorly, becoming better preserved specimens, the problem must remain grooved forward. Crura very slightly curved at their distal open. end. D e s c r ip t io n C o m p a r i s o n s Large-sized. Both valves shallow. Anterior commissure Before comparing Phacoiderhynchus n. gen. with the uniplicate to slightly parasulcate. Outline transversely middle-late (UD IV-V) Famennian genus Planovatiros­ elliptical in ventral and dorsal views. Commissure sharp, trum Sartenaer, 1970, to whichPhacoiderhynchus anti­ and projecting clearly postero-laterally where valve mar­ atlasicus n. gen., n. sp. has been assigned previously gins are concave. Frontal and lateral commissures clearly under the name Planovatirostrum undulatum, an up to and deeply indented by the costae. Sulcus and fold begin­ date reassessment of that genus is needed. ning imperceptibly at a great distance from the beak. The following species were already eliminated from External median costae on fold slightly higher than mid­ the genus Planovatirostrum: P. fibrosissimum ( T i e t z e , dle ones when fold is slightly depressed medially. Hinge 1870), and P. richteri (Oppenheimer, 1916). Apart from line relatively long. the originally figured specimen of P. fibrosissimum, this Flanks of pedicle valve flat to slightly convex, sloping late Famennian (UD VI) species from the Sudetes [Ebers- gently from umbonal region almost without relief. Well dorf near Neurode in county Glatz (Dzikowiec near Nowa marked shallow sulcus starting wide, widening rapidly, Ruda in county Klodzko nowadays)] is so far only known and wide at front. Bottom of sulcus flat to slightly convex. with two Thuringian specimens of the same age figured Tongue low, well defined, and trapezoidal. Top of tongue by W e y e r (1979, p. 103, pi. 4, fig. 14; 1990, p. 29, always lower, often considerably lower, than top of shell. fig. 14), Bartzsch & W eyer (1986, pi. I, right column, Upper part of tongue elongated anteriorly. Beak small, fig. 5), B a r t z s c h et «/.( 1993, fig. 14, p. 35), and B l u - wide, slightly incurved, overhanging the hinge line. Inter­ m enstengel (1995, pi. 4.3.4.-I, fig. 14, p. 141). On this area low, relatively long, clearly separated from flanks. limited base S a r t e n a e r & Xu (1989, p. 39) suggested Extremely short deltidial plates have been observed in that the species could probably be assigned to the genus serial transverse sections. Pugnaría B iernat & Racki, 1986. This problem will be Brachial valve slightly and uniformly convex. Flanks solved when more material allowing the investigation sloping gently towards the commissure. Fold low, clearly of the internal structure becomes available. Problems separated from flanks. Fold often marked on almost its connected with the late Famennian [UD V (and VI)] whole length by a very shallow depression affecting the Moravian species P. richteri, concerning which informa­ part between the external costae. Top of valve located tion is sparse, was discussed by S a r t e n a e r & Xu (1989, posterior to the frontal commissure. p. 38, p. 43, p. 44), and by S a r t e n a e r (1997, pp. 25-27, Costae in moderate number, clearly marked, high, p. 31, p. 32, pp. 33-34), who excluded from it represen­ regular, wide, and angular with rounded crest. Median tatives of the species mentioned from northern Sauerland costae arising with sulcus and fold. One to three divisions and southeastern Thuringia. S a r t e n a e r (1999, pp. 67-68, of median costae commonly present in the anterior half of p. 73) indicated that P. richteri could belong to the genus the shell, and even often in its anterior third or quarter, Tetragonorhynchus Sartenaer, 1999. break the regularity of the costation. Lateral costae sim­ The following species and forms from Morocco and ple, restricted to the anterior half of shell. No parietal Poland have also to be excluded from the genus Plano­ costae. vatirostrum on the basis of the morphological criteria Valves have subequal depths with maximum width of detailed below: Calvinaria undulata, Pseudoleior- shell somewhat anterior to mid-length. Maximum depth hynchus undulatus, Planovatirostrum undulatum,!Plano­ of brachial valve, and thus of shell, always located in vatirostrum cf. undulatus, and Planovatirostrum sp. posterior half, and from which point the valve slopes The following two conclusions regarding Moroccan gently towards the commissure. Very wide apical angle species are drawn from the discussion of the synonymy and angle of the cardinal commissure. (see below): (1) no specimen of the type series ofCalvi­ Shell moderately thick in the apical region.