The pharciceratid ammonoids from the Roteisenstein Formation of Dillenburg (Cephalopoda, Ammonoidea)

The ammonoids of the suborder Pharciceratina from the Red Ironstone Formation of the area around Dillenburg (eastern Rhenish Mountains) are revised, mainly based on historical collections stored in the Museum für Naturkunde, Berlin. The genus Evopharciceras gen. nov. and the following species are newly described: Maenioceras ornatum sp. nov., Pharciceras beyrichi sp. nov., Pharciceras kruegeri sp. nov., Pharciceras ferrum sp. nov., Evopharciceras formosum gen. et sp. nov., Extropharciceras metallicum sp. nov., Lunupharciceras kochi sp. nov., Stenopharciceras lotzi sp. nov., Pluripharciceras ahlburgi sp. nov. and Sandbergeroceras archiaci sp. nov. Neotypes are proposed for the species Extropharciceras becheri (von Buch, 1832) and Sandbergeroceras costatum (d’Archiac & de Verneuil, 1842). The stratigraphic distribution of the genera is discussed; they are assigned to three assemblages: (1) Maenioceras terebratum Zone (early Givetian; two species), (2) Pseudoprobeloceras pernai Zone (latest Givetian; fi fteen species) and (3) Sandbergeroceras costatum Zone (early Frasnian; three species).


Introduction
The study of late Givetian ammonoid assemblages is closely linked to the Roteisenstein (Red Ironstone) Formation in the Dillenburg and Oberscheld district at the eastern margin of the Rhenish Mountains. Almost all Late Givetian ammonoid species newly described before 1960 originate from the Dillenburg area, and most of these specimens were collected in the course of intensive underground ironstone mining. While many specimens from this mining area were distributed to various museums at the end of the 19 th and beginning of the 20 th century, there is hardly any new material since the decline in mining activities that led to the demise of mining in the 1970s (Georg et al. 1985;Stoppel 1988). Therefore, the revision of the Central European Late Givetian ammonoid species is entirely based on historical collections.
From the second half of the 20 th century, diverse late Givetian ammonoid assemblages have been discovered in the Anti-Atlas of Morocco (Petter 1959;Bensaïd 1974;Bockwinkel et al. 2009Bockwinkel et al. , 2013a. This material is much better preserved than the Rhenish material and allows a substantially better understanding of the morphological spectrum. Currently, about 40 ammonoid species are known from the Moroccan localities. The Moroccan material consists of both calcareous specimens and limonitic internal moulds.
In the following, we provide a re-description of the pharciceratid ammonoid material available in the collections of the Museum für Naturkunde, Berlin. The purpose of this description is to make the material of the classical sites from the Dillenburg area known in order to support a supra-regional comparison of time-equivalent assemblages.

The Red Ironstone of the Dillenburg district
The Red Ironstone of Dillenburg has been mined over a period of more than 2000 years; iron ores were already mined and smelted in the La Tène period in the vicinity of Oberscheld (Jockenhövel & Willms 1993). The iron ore brought great economic importance to the region around Dillenburg for centuries (Frohwein 1885;Georg et al. 1985); as early as the beginning of the 17 th century, hammer mills worked in the area around Oberscheld (Becher 1789).
The Ironstone is an exhalative-synsedimentary formation of haematite ores (so-called Lahn-Dill Type), which originated from ascending hydrothermal fl uids connected with basaltic volcanism. It overlies the so-called Schalstein and Mandelstein (= volcanic tuffi tes) and is in turn overlain by either Late Devonian shales or cephalopod limestones. The red ironstone ore deposit has been described as a succession of several layers up to 4 metres thick, which may be distributed over a sequence of layers up to 50 metres thick (e.g., Koch 1858;Frech 1888;Lotz 1902;Lotz in Kayser 1907a, 1907bKegel 1934aKegel , 1934bKegel , 1934cLippert & Hentschel in Lippert et al. 1970;Lippert & Nesbor in Bender et al. 1997). The siliceous iron ores occur in varying concentrations; they are often more or less intensively mineralised limestones that still show the carbonate microfacies and allow the extraction of the macrofossils.
An early geological explanation of the red ironstone ore was given by Lotz (in Kayser 1907a, 1907b, at that time on the basis of numerous accessible subsurface outcrops. He already pointed out the complicated bedding conditions including shallow overthrusts, that were an obstacle for creating a clear stratigraphic classifi cation of the layers. He accepted the hypothesis expressed shortly before by Harbort (1903) that the iron ores were primary in nature and related to diabase volcanism and postulated a formation caused by hot springs rich in carbon dioxide and iron in the aftermath of volcanic activity.
Lotz has already clearly shown that there are several layers of red ironstone and that the lithology of the individual layers can be very different. He distinguished between siliceous haematite ores and the so-called "Flußeisenstein"; the latter is rather to be regarded as mineralised limestone and yielded the most and best-preserved fossils.
It has long been known that the red ironstone shows considerable lateral changes in thickness. The thickness depends on the topography of the seabed; on submarine sills it is thicker and more enriched in iron than in the basins. Later studies on the palaeogeography of the red ironstone occurrences, which were carried out simultaneously with investigations of the conodont succession, were able to confi rm these results and supplement them in greater detail (Krebs 1959a(Krebs , 1959b(Krebs , 1960Krebs & Rabien 1964).
European Journal of Taxonomy 771: 1-79 (2021) Summaries of the geological conditions of the Roteisenstein of Dillenburg, its history of formation as well as its history of research were published in the explanations of the geological map sheets of Dillenburg and Oberscheld (Lippert & Hentschel in Lippert et al. 1970;Lippert & Nesbor in Bender et al. 1997).

Ammonoid stratigraphy
All the material studied herein is part of historical collections; therefore, little is known about the precise stratigraphic position of the various species. In some cases, assemblages from specifi c localities exist, but even these cannot be assumed with certainty to be from the same stratum. In several cases this is even excluded, for example when genera from both the Givetian (e.g., Pharciceras Hyatt, 1884) and the Frasnian (e.g., Manticoceras Hyatt, 1884) are named from the same locality (e.g., Königszug Mine). Even if the locality information is more precise (e.g., Königszug Mine, 60 m level), stratigraphically distinctly different genera (e.g., Pharciceras and Manticoceras) may have been collected together. Therefore, no precise stratigraphic classifi cation is possible on the basis of the available material.
However, this succession of ammonoid zones could not be demonstrated in any section; the zonation is rather based on the expectation that the progressive evolution towards more complex suture lines in pharciceratids is also refl ected in the stratigraphic succession of species and genera. The study of the species-rich assemblages in the Anti-Atlas of Morocco (Bockwinkel et al. 2009(Bockwinkel et al. , 2013a has shown that at least in these, there is a co-occurrence of the genera Pharciceras, Synpharciceras Schindewolf, 1940, Pseudoprobeloceras Bensaïd, 1974, Taouzites Korn, 2001, and sometimes also with Petteroceras Bogoslovsky in Bogoslovsky et al., 1962. All these occurrences would therefore be placed in either the Pseudoprobeloceras pernai Zone or the Petteroceras errans Zone. A similar biostratigraphic attribution might be true for the occurrences of Pharciceras and related genera in the Red Ironstone of Dillenburg. There is no evidence that the forms originate from widely separate horizons; on the contrary, the collections rather indicate a short interval in which most of the species described here lived together. However, only one rock can be used to support this hypothesis, which provided specimens of the species Pharciceras kayseri and Stenopharciceras lotzi sp. nov. The frequent occurrence of Pseudoprobeloceras pernai (Wedekind, 1918) in the Red Ironstone would speak for a most likely attribution to the Pseudoprobeloceras pernai Zone.

Material and methods
There was a total of about 165 specimens available for our study, most from the area of Dillenburg and some from Wetzlar at the eastern margin of the Rhenish Mountains (Fig. 2). The specimens are preserved in iron-rich micritic or sparitic limestone or in haematitic ironstone, some of them in a pure haematite ore. Most specimens are tectonically deformed laterally, but often the shell ornamentation is well preserved. Inner whorls and septa are often destroyed and replaced by coarse calcite, so that the important features of conch ontogeny and suture line are sometimes destroyed.
The material from the Red Ironstone Formation comes from four principal stratigraphic intervals, in ascending order: -middle Givetian (assemblage with Maenioceras Schindewolf, 1933) -late Givetian (assemblage with Pharciceras, Pseudoprobeloceras) -early Frasnian (assemblage with Koenenites Wedekind, 1913, Acanthoclymenia Hyatt, 1900) -middle Frasnian (assemblage with Manticoceras, Mesobeloceras Glenister, 1958 Almost all the material consists of isolated specimens without assignment to any stratigraphic scheme. Information on the co-occurrence of taxa could only rarely be obtained from the context of the collections. Most of the material kept in the fossil cephalopod collection of the Museum für Naturkunde, Berlin, was collected in a period between 1830 and 1930: Beyrich collected some material in the course of European Journal of Taxonomy 771: 1-79 (2021) The description of the material follows, as far as possible, the scheme for Palaeozoic ammonoids outlined by Korn (2010) and Klug et al. (2015) (Fig. 3). However, due to the limitation of ontogenetic data, the descriptions must remain incomplete. The embedding of most of the material in very hard ironstone precluded the complete preparation of most of the specimens. In addition, many of the specimens are tectonically distorted, so that photographing dorsal and ventral views was diffi cult. In the following, we therefore present reconstructed dorsal projections to give a better picture of the conch geometry.
= collection of fossil cephalopods in the Museum für Naturkunde, Berlin SMF.Mbg. = former collection of the Marburg University, now Senckenberg Museum, Frankfurt uw = umbilical width WER = whorl expansion rate wh = whorl height ww = whorl width

Results
Order Agoniatitida Ruzhencev, 1957Suborder Pharciceratina Korn, 1998Superfamiliy Pharciceratoidea Hyatt, 1900 Family Maenioceratidae Bogoslovsky, 1958 For a defi nition of the family and the included genera, see Korn & Klug (2002: 139). European Journal of Taxonomy 771: 1-79 (2021) distinct spiral groove. Suture line with very wide external lobe with acute ventrolateral saddle and a low median saddle, and a V-shaped lateral lobe and two U-lobes.

Description
The material from Wetzlar contributes little to the knowledge of the species. Specimen MB.C.4977.1 is a weakly deformed, comparatively well-preserved specimen with 45 mm conch diameter in haematitic ironstone and the best available specimen that allows the study of the adult conch (Fig. 5A). It is, at nearly 45 mm diameter, extremely discoidal with a very narrow umbilicus (ww / dm = 0.24; uw / dm = 0.06). The whorl profi le shows that the conch is widest in the midfl ank area; the fl anks stand parallel and are weakly convex. They converge towards the umbilicus to form a shallow groove, from which the umbilical margin is elevated like a low rim. The fl anks also converge towards the narrowly rounded venter, which is separated from the fl anks by a rather deep ventrolateral groove. The shell ornament is visible in a small area near the aperture and shows very weak growth lines.
MB.C.4976 is a rather poorly preserved specimen of 42 mm diameter, embedded in an ironstone slab (Fig. 5B). It shows the same conch proportions as specimen MB.C.4977.1.

Remarks
The type material from the Stringocephalus Limestone of Villmar is poorly preserved. It hardly allows an accurate description of the conch shape and the ornament. In addition, there is the rather small size of the lectotype which is 25 mm in diameter. The identifi cation of the specimens from the Roteisenstein is therefore mainly based on the compressed conch shape of the type material.
It is not certain whether the fi ndings reported from North Africa and Canada actually belong to M. terebratum. Göddertz (1987) described sickle-shaped furrows on the inner half of the fl ank of larger specimens from Algeria; apparently this feature does not appear in the specimens from the Rhenish Mountains. However, it is not clear whether the furrows are actually shell constrictions or internal shell thickenings.
Maenioceras terebratum differs from M. ornatum sp. nov. in the slenderer conch, the much narrower and rounded venter and the much weaker ornament with fi ner growth lines. Already Holzapfel (1895) discussed the morphological differences of specimens attributed by him to "Maeneceras terebratum" between the various occurences. However, he considered the difference in the weaker ornament of specimens from the Stringocephalus Limestone compared to the occurrence in the cephalopod limestone as caused by preservation. This is obviously not the case, as the specimens from the Red Ironstone of Wetzlar share the weak ornament with the specimens from the Stringocephalus Limestone of Villmar, but differ from the Red Ironstone specimens from Oberscheld.

Etymology
Named after the Latin 'ornatum', meaning 'decorated', because of the shell ornament.

Description
The description is based on three specimens: Holotype MB.C.30229.1: weakly deformed, comparatively well-preserved specimen with 23 mm conch diameter in red ironstone (Fig. 6C).
The three type specimens listed above allow the study of conch geometry and ornament between 20 and 35 mm conch diameter. They show thinly discoidal conchs with parallel fl anks; the whorl profi le is widest near the midfl ank, from where the fl anks slowly converge towards the umbilicus and a little faster towards the venter. Flanks and venter are separated by a narrowly rounded shoulder that is accompanied, on the fl ank side, by a shallow longitudinal groove.
Particularly in the holotype MB.C.30229.1, the ornament is well-preserved and shows lamellar growth lines with a broadly rounded dorsolateral projection, a slightly narrower lateral sinus, a very high and narrow ventrolateral projection and a very deep, narrow ventral sinus. Remains of the wrinkle-layer are preserved in the dorsal whorl area; they show very delicate lines.

Remarks
The new species was previously described by Holzapfel (1895) from well-preserved material from the Roteisenstein from Adorf (Fig. 7A). The large specimen illustrated by Holzapfel agrees very well with the specimens from Oberscheld in terms of conch form and ornament. Holzapfel already recognized the differences between the specimens from the Stringocephalus Limestone of Villmar (M. terebratum) and from the Roteisenstein of Oberscheld (M. ornatum sp. nov.) in the strength of the growth lines. However, he considered both forms to belong to M. terebratum.
The new species differs from Maenioceras terebratum in the stouter conch (ww / dm = 0.40-0.45 in M. ornatum sp. nov. at 30 mm conch diameter but 0.25-0.30 in M. terebratum), the wider and slightly fl attened venter and the much coarser ornament with lamellar growth lines.
Family Pharciceratidae Hyatt, 1900 For the systematics and taxon content of this family, see . Note that Bockwinkel et al. (2009Bockwinkel et al. ( , 2013a added several genera to the family.

Description
Holotype MB.C.22174 is laterally slightly deformed, completely chambered specimen with 34 mm conch diameter in haematitic limestone; small parts of the specimen are covered with shell, the phragmocone is fi lled with sparry calcite (Fig. 8). The specimen has a thickly discoidal and subevolute conch shape with a low coiling rate at 34 mm diameter; the whorl profi le is depressed with steep umbilical wall and broadly rounded fl anks and venter. Two faint ventrolateral spiral grooves on each side separate the fl anks from the venter, which is broadly rounded at the largest diameter of the specimen but fl attened up to the last volution (Fig. 9B). The ornament shows lamellar growth lines. The suture line has a very wide external lobe with nearly parallel fl anks and lanceolate prongs. Two lobes are located on the fl ank: the asymmetric lateral lobe that is larger than the prongs of the external lobe and the small, rounded U 2 lobe (Fig. 9A). A very small U 4 lobe is located on the umbilical wall.

Remarks
The two specimens, of which only the holotype is rather well-preserved, are described here as a new species because a conch morphology cannot be attributed to any other species of Pharciceras. Its conch is stouter (ww / dm ~ 0.55 at 35 mm conch diameter) than in most of the other species of Pharciceras. Juveniles of P. kruegeri sp. nov. are also stout, but they possess a narrower umbilicus (uw / dm ~ 0.33) than P. beyrichi sp. nov. (uw / dm ~ 0.38) and much weaker ventrolateral grooves.  Pharciceras tridens is a similar form, but is slenderer with a ww / dm ratio of ~ 0.45 at 35 mm conch diameter. In smaller stages at 25 mm diameter, the venter is broadly rounded in P. tridens, in contrast to the slightly fl attened venter in P. beyrichi sp. nov. Bockwinkel & Korn in Bockwinkel et al., 2013 Figs 10-13; Tables 4-5 Pharciceras oberscheldense Bockwinkel & Korn in Bockwinkel et al., 2013b: 262, text-fi gs 5-8.

Diagnosis
Species of Pharciceras with thickly discoidal, subevolute conch at 25 mm dm (ww / dm ~ 0.50; uw / dm ~ 0.32) and thinly discoidal, subevolute conch at 60 mm dm (ww / dm ~ 0.35; uw / dm ~ 0.30). Whorl profi le weakly depressed at 25 mm dm (ww / wh ~ 1.35) and weakly compressed at 60 mm dm (ww / wh ~ 0.90); whorl expansion rate low to moderate. Venter continuously rounded throughout ontogeny. Adult stage with slightly fl attened, converging fl anks bordered by a subangular ventrolateral shoulder from the slightly fl attened venter. Growth lines coarse, strongly biconvex; ventrolateral shoulder with two spiral grooves. Outer suture line with asymmetric, rounded prongs of the external lobe, a tongue-shaped lateral lobe, a small V-shaped U 2 lobe, and a shallow and wide U 4 lobe.

Paratypes
Paratype MB.C.3655: incomplete specimen with 48 mm conch diameter in iron-rich limestone; probably the last volution belongs to the body chamber (Fig. 10D).
Paratype MB.C.3662: incomplete specimen with 33 mm conch diameter in iron-rich micritic limestone; the specimen is fi lled with sparry calcite. The specimen is fully chambered, body chamber missing.
Paratype MB.C.22161: fairly well-preserved specimen with 65 mm conch diameter in haematitic limestone. The specimen is broken apart and allows the study of an inner whorl and its suture line (Figs 10B, 11A).  Paratype MB.C.22168: incomplete steinkern specimen with 47 mm conch diameter in iron-rich limestone; the complete last volution belongs to the body chamber (Fig. 10C).
Hototype MB.C.3620 has in the last volution at 76 mm diameter a discoidal and subevolute conch (ww / dm = 0.32; uw / dm = 0.31) with moderately high coiling rate (WER ~ 1.87); the whorl profi le is compressed (ww / wh = 0.77) with narrow umbilical wall and slightly fl attened fl anks which converge towards the subangular ventrolateral shoulder. In the penultimate whorl, the venter is broadly rounded. Here, two shallow ventrolateral spiral grooves are accompanied by low ridges on each side. Lamellose growth lines are well-preserved here and extend with a wide dorsolateral projection, a broad lateral sinus, and a very pronounced, narrow ventrolateral projection across the fl anks. The suture line has, at approximately 34 mm conch diameter, a very wide external lobe, in which the prongs are slightly pouched. Two V-shaped lobes are located on the fl ank (Fig. 11A), a narrowly rounded U 2 and a shallow and wide A 4 lobe.

Remarks
Pharciceras oberscheldense is a common species in the Red Ironstone from Dillenburg and specimens of this species were obviously often referred to as P. tridens. This includes the specimen fi gured by Frech (1888), which cannot be assigned to P. tridens because of its rather narrow umbilicus, which has only one third of the conch diameter ( Fig. 12) and probably also the specimen fi gured by Wedekind (1918: pl. 20 fi g. 7) (Fig. 13).
Pharciceras oberscheldense belongs to the more narrowly umbilicate species of the genus (uw / dm ~ 0.30 at 30-40 mm dm) and differs in this respect from P. tridens and P. kochi sp. nov. (uw / dm ~ 0.40). Among the narrowly umbilicate species of Pharciceras, P. oberscheldense differs from P. ferrum sp. nov. in the shape of the lateral lobe (rounded in P. oberscheldense but V-shaped in P. ferrum sp. nov.) and in the wider whorl profi le (ww / wh ~ 1.05 at 50 mm dm in P. oberscheldense but only ~ 0.80 in P. ferrum sp. nov.). (Sandberger & Sandberger, 1850

Description
Five specimens are selected for description and illustration: Lectotype 29 in the Wiesbaden Museum: Rather poorly preserved, corroded specimen with 26 mm conch diameter in iron-rich limestone (Fig. 14).
MB.C.3647: incomplete specimen with 46 mm conch diameter in iron-rich micritic limestone with body chamber occupying the last volution (Fig. 15B).
Lectotype 29 is a specimen of less than 30 mm diameter and allows the study of conch shape and suture line of the preadult stage. The conch is discoidal and subevolute with a crescent-shaped whorl profi le. The shell is largely removed and only at some parts preserved with rather coarse growth lines. The suture line has U-shaped prongs of the external lobe and a tongue-shaped lateral lobe.

European Journal of Taxonomy 771: 1-79 (2021)
The four specimens MB.C.3634, MB.C.3663, MB.C.3647 and MB.C.3618 allow the study of conch geometry, ornament and suture line between 27 and 57 mm conch diameter. The general conch morphology is similar during this interval, but the conchs become slenderer (ww / dm decreasing from ~0.47 to ~0.39), paralleled by fl attening of the whorl profi le (ww / wh decreasing from ~1.45 to ~1.20). All specimens show double ventrolateral grooves.
Specimen MB.C.3618 shows the suture line, which has a very wide external lobe with a median saddle attaining about 60% of the lobe depth and lanceolate prongs. The lateral lobe is much shorter than the external lobe; it is tongue-shaped with a narrowly rounded base. On the fl anks and umbilical margin follow two very small, rounded umbilical lobes (Fig. 16A).

Remarks
Unfortunately, the lectotype of Pharciceras tridens is a rather small and poorly preserved specimen with only 26 mm conch diameter (Fig. 14); therefore, it may be diffi cult to compare this with the other species of the genus, which are defi ned by larger type material. The type specimen allows at least to fi gure two characters that can be used to characterise the species, the fi rst is the rather wide umbilicus (uw / dm ~ 0.40) and the tongue-shaped, rounded or blunt lateral lobe.
Only one species from the Red Ironstone has an umbilicus as wide as that in P. tridens, it is P. beyrichi sp. nov. but this differs in its much stouter conch with a much broader whorl profi le (ww / dm ~ 0.45 and  European Journal of Taxonomy 771: 1-79 (2021) ww / wh ~ 1.40 in P. tridens but ww / dm ~ 0.55 and ww / wh ~ 1.75 in P. beyrichi sp. nov.). Furthermore, the ventrolateral grooves are much deeper in P. beyrichi sp. nov.
The species name Pharciceras tridens has frequently been used in the past decades for all specimens with a rather wide umbilicus and little differentiated suture line. For a secure classifi cation of these specimens, a comprehensive revision would be necessary, which, however, is outside the scope of the present study. These mentions in the literature are therefore marked with a question mark in the list of synonyms. Wedekind, 1918 Figs 17-19; Tables 8-9 Pharciceras Kayseri Wedekind, 1918: 127, 169, pl. 20
The material allows the description of conch geometry and ornament of the growth interval between 42 and 80 mm conch diameter. In this interval, the conch becomes slenderer (ww / wh decreases from ~ 0.42 to ~ 0.28), while the umbilical opening rate is rather constant (uw / dm ~ 0.25). The coiling rate increases slowly form WER ~ 1.70 to ~ 1.85. The whorl profi le is rounded triangular, it is widest near the rounded umbilical margin. The fl anks are weakly convex and converge towards the narrowly rounded venter. Two faint ventrolateral grooves are present in all specimens. Shell remains are preserved only occasionally; it appears that the growth lines are very delicate, even in the inner whorls.
The suture line of specimen MB.C.30235.1 has a large external lobe with a median saddle raised to three quarters of the lobe depth (Fig. 19A). On the fl anks, there is a rather small, V-shaped lateral lobe and an even much smaller, V-shaped umbilical lobe.

Remarks
Pharciceras kruegeri sp. nov. is a similar species but differs in the stouter conch (ww / dm ~ 0.40; ww / wh ~ 1.05) from P. kayseri (ww / dm ~ 0.30; ww / wh ~ 0.65) at 60 mm diameter. The ornament reveals more Pharciceras ferrum sp. nov. is rather similar in conch proportions, but differs in less strongly convergent fl anks and wider venter. P. galeatum is similar in the juvenile and preadult stage, but is more widely umbilicate and develops a tectifom venter in the adult stage.
The Moroccan specimens, placed in P. kayseri by Bockwinkel et al. (2009), differ in the suture line; they have short lobes of about the same height, while the Rhenish material has deep lobes of varying depth. Furthermore, the Moroccan specimens are stouter and the umbilicus is wider and the venter is not tabulate in P. kayseri.

Etymology
Named after the teacher Krüger (Hagen), who provided an important collection of fossils from the Red Ironstone.

Description
Five specimens are selected for description and illustration: Holotype MB.C.22170: laterally deformed, incomplete specimen with 65 mm conch diameter in haematitic ironstone; the last volution belongs almost completely to the body chamber (Fig. 20A).
Paratype SMF.Mbg.6359: laterally strongly deformed specimen with 94 mm conch diameter in haematitic ironstone; the last volution belongs almost completely to the body chamber (Fig. 21).
Paratype MB.C.3654: slightly deformed, well-preserved steinkern specimen with 32 mm conch diameter fi lled with sparry calcite. Nearly the entire last volution belongs to the body chamber (Fig. 20D).
Holotype MB.C.22170 and paratype MB.C.22162 are, at 65 and 54 mm conch diameter, similar in their proportions and represent the adult stage of the species (Fig. 20A-B). In this stage, the conch is discoidal and subinvolute with moderate coiling rate; the whorl profi le rounded triangular with steep umbilical wall, rounded umbilical margin and strongly converging fl anks. The evenly rounded venter is separated from the fl anks by two shallow spiral grooves. Both specimens possess ornament with lamellar, biconvex growth lines.
The smaller paratype MB.C.3654 with 32 mm conch diameter (Fig. 20D) is attributed to this species because it shows a conch geometry that is present in the earlier whorls of the two larger individuals. The conch is thinly pachyconic and subevolute; the whorl profi le is depressed with rather steep umbilical wall and broadly rounded fl anks and venter. Two very shallow spiral grooves are visible on the ventrolateral shoulder on both sides. Only some shell remains are preserved, they indicate coarse biconvex growth lines with a very high and narrow ventrolateral projection, which has a position at the spiral grooves. The suture line has, at a conch diameter of about 22 mm, a very wide external lobe with subparallel fl anks and two V-shaped lobes on the fl ank, of which the outer (lateral lobe) has the size of the prongs of the external lobe, and the inner one (U 2 lobe) is small (Fig. 22A), the U 4 lobe is shallow and wide.
The large paratype SMF.Mbg.6359 with 94 mm diameter shows that the conch proportions change towards a more slender conch geometry with a narrower venter. The specimen shows that the longitudinal grooves are still present in this stage (Fig. 21).

Remarks
Among the species from the Red Ironstone, Pharciceras kayseri is most similar but differs in the slenderer conch (ww / dm ~ 0.30; ww / wh ~ 0.65) from P. kruegeri sp. nov. (ww / dm ~ 0.40; ww / wh ~ 1.05) at 60 mm diameter. The ornament consists of very delicate growth lines in P. kayseri but coarse growth lines in P. kruegeri sp. nov.
The wide conch with the rounded-triangular whorl profi le makes it rather easy to separate P. kruegeri sp. nov. from the other species of Pharciceras.  Tables 12-13 Diagnosis Pharciceras with thinly discoidal, subevolute conch at 30 mm dm (ww / dm ~ 0.42; uw / dm ~ 0.32); extremely discoidal, subevolute at 60 mm dm (ww / dm ~ 0.32; uw / dm ~ 0.32). Whorl profi le nearly circular at 30 mm dm (ww / wh ~ 1.05); weakly compressed at 60 mm dm (ww / wh ~ 0.75); whorl expansion rate low to moderate. Venter continuously rounded throughout ontogeny. Adult stage with broadly convex, converging fl anks continuing to the narrowly rounded venter. Growth lines coarse, strongly biconvex; ventrolateral shoulder with two spiral grooves. Outer suture line with symmetric, U-shaped, blunt prongs of the external lobe, a V-shaped lateral lobe and a shallow and wide U 2 lobe.

Etymology
Named after the Latin 'ferrum', meaning 'iron', after the occurrence of the specimen in iron ore.

Description
Six specimens are selected for description and illustration: Holotype MB.C.30238: laterally deformed steinkern specimen with 78 mm conch diameter at the contact between a basaltic volcanic rock and a haematite ore (Fig. 23A). Paratype MB.C.22165: incomplete, laterally deformed specimen with 50 mm conch diameter in haematite ore. Parts of the suture line are visible (Fig. 23C).
The material allows the description of conch geometry from 29 to 78 mm diameter. During this interval, the ww / dm ratio decreases continuously from 0.45 to 0.30, while the umbilical width ratio is stable at 0.30-0.35. The coiling rate is also rather stable between 1.62 and 1.78. Holotype MB.C.30238 has, at 75 mm diameter, a compressed whorl profi le with very shallow umbilical wall, convergent fl anks and a narrowly rounded venter (Fig. 23A). A pair of faint spiral grooves is present in the ventrolateral area. Shell ornament is preserved in some specimens; it possesses coarse biconvex growth lines, which have an appearance of faint riblets in the inner whorls visible in the umbilicus of some specimens.
Paratype MB.C.3646 shows the suture line of the preadult stage (Fig. 24A); at a phragmocone diameter of 24 mm, it shows a parallel-sided external lobe with lanceolate, blunt prongs. The lateral lobe is V-shaped with weakly convex fl anks and the U 2 lobe is small and rounded.

Diagnosis
Pharciceras with extremely discoidal, subevolute conch at 80 mm dm (ww / dm ~ 0.27; uw / dm ~ 0.35). Whorl profi le weakly compressed at 80 mm dm (ww / wh ~ 0.65); whorl expansion moderate (WER ~ 1.95). Venter narrowly rounded in the preadult stage; adult stage with strongly converging fl anks bordered by a subangular ventrolateral shoulder from the tectiform venter. Growth lines coarse, strongly biconvex; ventrolateral shoulder with two spiral grooves. Outer suture line with symmetric, V-shaped prongs of the external lobe, a V-shaped lateral lobe, and a small rounded U 2 lobe.

Description
Holotype SMF.Mbg.2316 is a rather well-preserved but incomplete specimen with 74 mm conch diameter in red ironstone (Fig. 25). It allows the study of the adult conch as well as portions of the inner whorls. Its last volution is extremely discoidal and subevolute. It is widest at the rounded umbilical margin, from where the fl anks strongly converge towards the tectiform venter. This shape of the venter is developed only during the last half volution; the venter is still rounded at 180 degrees before the largest Fig. 25. Pharciceras galeatum Wedekind, 1918, specimen SMF.Mbg.2316(Welsch 1913 from Oberscheld (Prinzkessel Mine); reproduction from Wedekind (1918: pl. 20 fi g. 1). Scale bar units = 1 mm. Wedekind, 1918. A. Specimen MB.C.22182 (Koch Coll.) from Oberscheld (Anna Mine). B. Specimen MB.C.22180 (Kegel 1927 Coll.) from Oberscheld (Sahlgrund Mine). Scale bar units = 1 mm.

Fig. 26. Pharciceras galeatum
European Journal of Taxonomy 771: 1-79 (2021) diameter. The ventrolateral shoulder bears two longitudinal grooves on each side. The inner whorls are very evolute and it appears that the whorl profi le is crescent-shaped throughout most of the ontogeny.
The suture line of the holotype has a wide external lobe with a median saddle attaining more than half of the lobe depth (Fig. 27A). The prongs of the external lobe are V-shaped and symmetric. They are separated from the V-shaped lateral lobe by a rather narrow, rounded ventrolateral saddle. The U 2 lobe is rather small and rounded.
MB.C.22182 is an incomplete specimen with 88 mm conch diameter in red ironstone; the last volution belongs almost completely to the body chamber (Fig. 26A). It has an extremely discoidal and subevolute conch; the whorl profi le is compressed with shallow umbilical wall, rounded umbilical margin, and convergent fl anks that are widest at some distance from the umbilicus. The venter is narrowly rounded in the penultimate whorl, but developing into a subacute shape with a rounded keel at the end of the last volution. The inner whorls display coarse growth lines which become fi ner on the last volution. Runzelschicht is present in the dorsal whorl zone; it consists of fi ne wrinkles with slightly prorsiradiate direction.
MB.C.22180 is an incomplete specimen with 69 mm conch diameter in iron-rich micritic limestone, with several calcite veins cutting through (Fig. 26B). It shows very similar conch proportions; the whorl profi le is also compressed with shallow umbilical wall, rounded umbilical margin, and convergent fl anks. The narrowly rounded venter is separated from the fl anks by a subangular margin accompanied by a shallow spiral groove. In the penultimate whorl, the venter develops into a subacute shape with a rounded keel at the end of the last volution. The inner whorls show a rather well-preserved ornament; the growth lines are coarse in the inner whorls and slightly fi ner on the last volution.

Remarks
Pharciceras galeatum is, in the adult stage, easily separable from all other pharciceratids by its tectiform venter. A clear separation using conch characters in small specimens may be diffi cult, but the compressed whorl profi le and the rather narrow venter may serve as good criteria. The suture line provides another character for a separation, as P. galeatum possesses V-shaped ventrolateral prongs and a V-shaped lateral lobe. Pharciceras galeatum has some similarity to Oxypharciceras chebbiense Bockwinkel, Becker & Aboussalam, 2017, but differs in the shape of the venter, which is distinctively oxyconic from ca 60 mm dm in O. chebbiense but tectiform in P. galeatum.

Diagnosis
Pharciceratinae with evolute juvenile and adult stage, whorl profi le moderately to strongly depressed. Adult stage with weakly depressed whorl profi le; venter rounded. WER low or moderate. Juvenile stage sometimes fi nely ribbed, adult stage with weak to strong, single or paired ventrolateral grooves. Suture line with wide external lobe, short E 1 lobe, high median saddle, deep lanceolate E 2 lobe, large, deep lanceolate lateral lobe, two outer and two inner umbilical lobes. Suture line formula (E 2 E 1 E 2 ) L U 2 U 4 : U 3 U 1 I.

Remarks
The new genus differs from Pharciceras fi rst in the conch geometry with a high umbilicus / diameter ratio in all stages, which in Pharciceras decreases in the course of ontogeny. Second, the two genera are distinguished in the form of the external lobe: in Pharciceras the median saddle is low and usually does not reach half the height of the external lobe; in Evopharciceras gen. nov., however, the median saddle is very high and reaches more than three-quarters the height of the external lobe.

Etymology
Named after the Latin 'formosum', meaning 'beautiful', because of the decorated shell.

Description
Paratype MB.C.22173: Laterally deformed, but otherwise well-preserved specimen with 35 mm conch diameter in iron-rich micritic limestone. Most of the specimen is covered with shell; a quarter of the last volution belongs to the body chamber (Fig. 28B). It has a discoidal and evolute conch with low coiling rate (Fig. 28B); the whorl profi le is subcircular with shallow umbilical wall, broadly rounded fl anks and a broadly rounded venter. One faint ventrolateral spiral groove on each side separates fl anks and venter. The ornament includes lamellar growth lines, which extend with low dorsolateral projection on the umbilical margin, a shallow lateral sinus, a prominent, narrow ventrolateral projection and a deep ventral sinus.
The larger holotype MB.C.30241 is a laterally strongly deformed specimen with about 65 mm conch diameter in haematitic limestone, showing the suture line (Fig. 28A). It has a similar conch geometry, but is slightly slenderer. It displays the suture line, which has a rather narrow external lobe with high median saddle and narrow and slightly pouched, lanceolate prongs. The lateral lobe is also very narrow and lanceolate; the U 2 lobe is very narrow and the U 4 lobe is V-shaped and wider than the U 2 lobe (Fig. 29A).  (Lotz 1901 from Oberscheld (Beilstein Mine). B. Paratype MB.C.22173 (Koch Coll.) from Oberscheld (Anna Mine). Scale bar units = 1 mm.

Remarks
Evopharciceras formosum gen. et sp. nov. is similar to Extropharciceras metallicum sp. nov. but differs in the slightly stouter conch and the slightly narrower umbilicus. The suture line provides more specifi c criteria for the separation of the two species: while the E 2 , L and U 2 lobes are very narrow and lanceolate in Evopharciceras gen. nov., they are wider and tongue-or V-shaped in Extropharciceras.

Diagnosis
Pharciceratinae with discoidal to pachyconic, subevolute to evolute juvenile stage, whorl profi le depressed. Adult stage subinvolute to subevolute with weakly depressed to weakly compressed whorl profi le; venter rounded or tabulate. WER low or moderate. Juvenile stage sometimes fi nely ribbed, adult stage with weak to strong, single or paired ventrolateral grooves. Suture line with very wide external lobe, deep or shortened median E 1 lobe, moderately high median saddle, deep, tongue-shaped E 2 lobe, large, midfl ank lateral lobe, two or three outer and three inner umbilical lobes. Suture line formula (E 2 E 1 E 2 ) L U 2 U 4 : U 5 U 3 U 1 I to (E 2 E 1 E 2 ) L U 2 U 4 U 6 : U 5 U 3 U 1 I.

Included species
Extropharciceras conex Bockwinkel, Becker & Ebbighausen, 2009 Diagnosis Extropharciceras with extremely discoidal, evolute conch at 60 mm dm (ww / dm ~ 0.25; uw / dm ~ 0.50). Whorl profi le weakly depressed or weakly compressed with convergent fl anks and broadly rounded venter, umbilical wall steep. Growth lines rather coarse, strongly biconvex; ventrolateral shoulder with two spiral grooves in the middle growth stage. Outer suture line with lanceolate prongs of the external lobe, a tongue-shaped lateral lobe with acute base and V-shaped U 2 and U 4 lobes and a very small, rounded U 6.

Etymology
Named after the Latin 'metallicum', because of the origin of the specimens from iron ore.

Description
Four specimens are selected for description and illustration: Holotype MB.C.22151: rather well-preserved specimen with 61 mm conch diameter embedded in a block of haematite ore (Fig. 30A).
Holotype MB.C.22151 has an extremely discoidal and evolute conch (uw / dm = 0.49); the whorl profi le is compressed with oblique umbilical wall, rounded umbilical margin and slowly converging fl anks and narrowly rounded venter (Fig 30A). Venter and fl anks separated by a shallow spiral groove that is accompanied by delicate ridges. Lamellar biconvex growth lines are well-preserved on the specimen; they extend strongly biconvex on the fl ank to form a narrow and high ventrolateral projection. The ventral sinus is narrow and deep.
None of the specimens shows a complete outer suture line; in specimen MB.C.30242, for instance, the median saddle cannot be studied. The lateral prongs of the external lobe appears to be rather narrow and lanceolate. The lateral lobe is tongue-shaped but acute at its base; the U 2 and U 4 lobes are narrow and V-shaped, the U 6 lobe is small and rounded (Fig. 31A).

Diagnosis
Extropharciceras with thinly pachyconic, evolute conch at 20 mm dm (ww / dm ~ 0.60; uw / dm ~ 0.45), thickly discoidal, subevolute conch at 40 mm dm (ww / dm ~ 0.50; uw / dm ~ 0.40) and thinly discoidal, subevolute conch at 80 mm dm (ww / dm ~ 0.35; uw / dm ~ 0.35). Whorl profi le changing from strongly depressed in the juvenile stage (ww / wh ~ 2.30) to weakly compressed in the adult stage (ww / wh ~ 0.95). Whorl profi le crescent-shaped with continuously rounded venter up to 35 mm dm; adult stage with slightly fl attened, convergent fl anks bordered by a pronounced ventrolateral shoulder from the slightly fl attened venter. Growth lines fi ne, strongly biconvex; ventrolateral shoulder with two spiral grooves in the middle growth stage. Outer suture line with symmetric, lanceolate prongs of the external lobe, a V-shaped lateral lobe and small, V-shaped U 2 , U 4 and U 6 lobes.

Remarks to the type material
The original specimen described by von Buch (1832) was from the Goldfuß collection and could not be traced; it is missing in the Bonn collection and probably lost. Therefore, a neotype (MB.C. 3609) from the type area is proposed here. The selection of this neotype stabilises the use of the species name, which was mainly coined by Frech (1888Frech ( , 1897Frech ( -1902Frech ( , 1902.

European Journal of Taxonomy 771: 1-79 (2021)
As the species description provided by von Buch (1832) can hardly be used for a defi nition of the species, we herein refer to the description by Beyrich (1837a, 1837b), which allows a characterisation of the species. As the original specimen fi gured by Beyrich could not be traced, we propose herein a neotype from the Volpertseiche Mine near Oberscheld.
[The original specimen of von Buch (1832) came from the Rinzenbach Mine near "Edbach" (or "Eybach"). This mine was located between Eibach and Oberscheld and was later included in the Königszug Mine.]

Description
Three specimens are selected for description and illustration: Neotype MB.C.3609: well-preserved specimen with nearly 100 mm conch diameter in the contact zone between a pillow diabase and an iron-rich sparitic limestone (Fig. 32A).
MB.C.3613: slightly deformed specimen with 52 mm conch diameter in iron-rich sparitic limestone; the last quarter of the last volution belongs to the body chamber (Fig. 32B).
Neotype MB.C.3609 with nearly 100 mm conch diameter has an extremely discoidal and subevolute conch with a moderate coiling rate (Fig. 32A); the whorl profi le is pear-shaped in the last volution with a shallow umbilical wall, a broadly rounded umbilical margin, rather strongly convergent fl anks, a subangular ventrolateral shoulder and a rounded venter. The ventrolateral shoulder is much more rounded half a volution earlier (at 73 mm dm). A ventrolateral groove on each side is well-preserved another half whorl earlier (at 52 mm dm). Shell remains are preserved in the inner whorls and also on the last volution, but here only on the umbilical wall and the inner fl anks. The course of the fi ne growth lines on the last volution is biconvex with a rather high and rounded dorsolateral projection. Inner whorls show coarser growth lines, which possess a very prominent, narrow ventrolateral projection.
MB.C.3613 has, at a diameter of 52 mm, a discoidal and subevolute conch and a whorl profi le with rather steep umbilical wall, a rounded umbilical margin, convergent fl anks and a broadly rounded venter (Fig. 32B). The growth lines can be best seen in the area 270-360 degrees before the preserved aperture; their course is strongly biconvex with very prominent, very narrow ventrolateral projection. The growth lines are here superimposed by the Runzelschicht, which consists of fi ne wrinkles with radial direction. The outer suture line can be seen on the last preserved volution; at a conch diameter of about 39 mm it shows a wide external lobe with nearly parallel fl anks and four V-shaped lobes on the fl ank, which continuously become smaller towards the umbilicus (Fig. 33B).
The sectioned specimen MB.C.30247 allows the study of the ontogenetic changes of conch geometry from the earliest whorls up to a diameter of 92 mm (Fig. 33A). The most conspicuous morphological change concerns the whorl profi le, which is depressed in the whorls of the early and preadult stage but compressed in the adult stage. The whorl profi le is widest in a growth interval between 4.5 and 18 mm conch diameter, when the ww / wh ratio exceeds a value of 2.00. Up to a conch diameter of 38 mm, the whorl profi le is crescent-shaped with a very broad venter. Thereafter, the whorls become higher with narrowing of the venter. The last half whorl, between 68 and 92 mm dm, shows slightly fl attened, convergent fl anks that are slightly incurved in the ventrolateral area. At the largest diameter, the ventrolateral shoulders are pronounced and separate the fl anks from the weakly fl attened venter. The uw / dm ratio increases in early ontogeny up to 6 mm dm to a value of 0.50; thereafter, a nearly continuous decrease to a value of 0.35 in the terminal stage can be observed. The coiling rate decrease in early ontogeny and slowly increases to a maximum value of 1.82 at 92 mm dm (Fig. 33C-F).

Remarks
The description and the fi gure of "Ammonites Becheri" by von Buch (1832) gives little information about the morphology of the species. Beyrich (1837a, 1837b) provided a better illustration; it shows a species with evolute inner convolutions and quite high adult whorl (Fig. 34B). Finally, Frech (1888) gave a more detailed description and illustration (Fig. 34A); the species Extropharciceras becheri is redefi ned here based on this description and fi gure.

KORN D. & BOCKWINKEL J., Ammonoids from the Roteisenstein Formation
Extropharciceras becheri differs from E. metallicum sp. nov. from the Roteisenstein in that it has considerably wider whorls and the adult stage with a fl attened venter. Differentiation from some species of Pharciceras is more diffi cult if the suture line is not visible. But here, too, a demarcation can be ensured by the conch form; E. becheri shows the combination of very evolute inner whorls and a fl at venter, which is not known in the species of Pharciceras from the Roteisenstein.
Extropharciceras becheri has some similarity in the shape of the conch to Allopharciceras maximum from the Anti-Atlas of Morocco , but differs in the ontogeny of the suture, which shows irregular insertion of umbilical lobes in A. maximum.

Diagnosis
Pharciceratinae with discoidal subevolute to evolute juvenile stage, whorl profi le weakly depressed. Adult stage discoidal and subevolute to evolute with compressed whorl profi le; WER moderate, venter rounded or tabulate. Adult stage with or without ventrolateral grooves. Suture line with wide external lobe, short E 1 lobe, high median saddle, deep lanceolate E 2 lobe, smaller lanceolate lateral lobe, three outer and two or three inner umbilical lobes. Suture line formula sequence of the fi ve or six U lobes so far ambiguous and controversial.
MB.C.3642: weakly deformed specimen with 57 mm conch diameter in iron-rich micritic limestone; phragmocone fi lled with sparry calcite. Half of the last whorl belongs to the body chamber, the last suture line is well exposed at the calcite-micrite contact (Fig. 36A).

KORN D. & BOCKWINKEL J., Ammonoids from the Roteisenstein Formation
MB.C.22121 is sectioned and shows the conch ontogeny from the initial stage up to a conch diameter of 31 mm (Fig. 37A).
The cross section of specimen MB.C.22121 demostrates that the trajectories of the conch parameters are very different (Fig. 37A): while the ww / dm trajectory is nearly monophasic with a rather continuous decrease from 0.55 at 1 mm dm to 0.33 at 31 mm dm, the uw / dm trajectory has an irregular undulating course with values ranging between 0.40 and 0.50. The coiling rate is rather high (1.88-2.01) in the early juvenile stage up to 4 mm dm, it is lower (down to 1.64 at 7 mm dm) and shows a subsequent increase to nearly 2.00 at 31 mm dm.
The largest available specimen MB.C.3642 (Fig. 36A) with 57 mm conch diameter allows the study of the adult stage. The conch is extremely discoidal and subinvolute with a high coiling rate; the whorl profi le is compressed with a steep umbilical wall, subparallel fl anks and rounded venter on the fi rst three quarters of the last volution. At the largest diameter of the specimen, the venter is slightly fl attened and  (Sandberger & Sandberger, 1850). A. Cross section of specimen MB.C.22121 from Oberscheld. B. Suture line of specimen MB.C.3642 (Kegel 1927 Coll.) from Oberscheld (Sahlgrund Mine), at dm = 35.0 mm, ww = 10.5 mm, wh = 14.5 mm. C. Suture line of specimen MB.C.3648 (Kegel 1927 Coll.) from Oberscheld (Sahlgrund Mine), at dm = 42.0 mm, ww = 12.5 mm, wh = 16.5 mm. D-G. Ontogeneric trajectories of the cardinal conch parameters. Abbreviations: see Material and methods. Scale bar units = 1 mm. (Sandberger & Sandberger, 1850); reproduction of the specimen illustrated by Frech (1888: pl. 2 fi g. 3). Scale bar units = 1 mm.

Fig. 38. Lunupharciceras lunulicosta
European Journal of Taxonomy 771: 1-79 (2021) separated from the fl anks by a pronounced ventrolateral shoulder. Shell ornament is not preserved, but at some places, impressions of strengthened growth lines can be seen on the outer fl anks. The suture line has, at 35 mm conch diameter, a very wide external lobe with parallel-sided, blunt prongs, a parallelsided, rounded lateral lobe and a smaller U 2 lobe of the same shape (Fig. 37B).
Specimen MB.C.3648 (Fig. 36B) shows the morphological change from the widely umbilicate juvenile stage to the more involute adult stage. The conch is extremely discoidal and subevolute with high coiling rate; the whorl profi le is compressed with a rounded umbilical wall, subparallel fl anks and rounded venter. The suture line has, at 42 mm phragmocone diameter, a wide parallel-sided external lobe with lanceolate prongs. Four lobes are visible on the fl anks and umbilical wall; while the lateral lobe is lanceolate and acute, the U 2 -U 6 lobes are rounded (Fig. 37C).
Specimens MB.C.22171 (37 mm conch diameter), MB.C.3666 (29 mm) and MB.C.3667 (29 mm) demonstrate the decrease of the umbilical width ratio, which parallels the whorl profi le becoming more compressed. Specimen MB.C.3666 shows the shell ornament with fi ne, biconvex growth lines that possess a high ventrolateral projection and a deep ventral sinus, while specimen MB.C.3667 appears to be smooth.

Remarks
Lunupharciceras lunulicosta differs from the co-occurring L. kochi sp. nov. in the narrower umbilicus. Lunupharciceras lunulicosta is subevolute at 20 mm conch diameter (uw / dm ~ 0.40), while L. kochi Table 21. Conch dimensions and ratios of selected specimens of Lunupharciceras lunulicosta (Sandberger & Sandberger, 1850  sp. nov. is still evolute (uw / dm ~ 0.47). At 50 mm conch diameter, the difference is even larger (uw / dm ~ 0.30 in L. lunulicosta but more than 0.40 in L. kochi sp. nov.). The difference in the umbilical width can easily be seen in specimens in which the matrix has been cleaned from the umbilicus.
The material attributed by Bockwinkel et al. (2013a) to L. lunulicosta is fragmentary and diffi cult to assign. It can therefore not be determined whether it actually belongs to this species.

Description
Five specimens are selected for description and illustration: Holotype MB.C.3627: incomplete, laterally partly deformed specimen with 83 mm conch diameter in sparitic, iron-rich limestone. It is a steinkern in which the right side is better preserved than the left side, the penultimate whorl shows suture lines. The last half of the terminal volution belongs to the body chamber (Fig. 39A).
Paratype MB.C.22181: rather well-preserved steinkern specimen with 24 mm conch diameter preserved haematitic ironstone (Fig. 39E). Holotype MB.C.3627 with 83 mm conch diameter has a conch that is extremely discoidal and subevolute; the whorl profi le is compressed and widest near the umbilical shoulder. The coiling rate is moderate, the umbilical wall is shallow and rounded and the fl anks converge slowly towards the angular ventrolateral shoulder that delimits the fl ank from the slightly fl attened venter (Fig. 39A). The steinkern shows traces of rhythmically strengthened growth lines, producing shallow folds on fl anks and venter. These folds are particularly strong on the outer fl ank. Course of the growth lines is strongly biconvex with a rather high and wide dorsolateral projection, a shallow lateral sinus, and a narrow ventrolateral projection. The inner whorls appear to be smooth, but they are not well-preserved. However, they demonstrate that the conch shape of the juvenile stage is strikingly different from the adult stage, as it is serpenticonic with slowly expanding volutions.
The smaller paratype MB.C.22186 with 57 mm conch diameter shows the transformation from the preadult to the adult stage. It also has an extremely discoidal and subevolute conch with moderate coiling rate; the whorl profi le is compressed with steep umbilical wall, rounded umbilical margin, and fl attened, slowly converging fl anks and narrowly rounded venter. Lamellar, biconvex growth lines are visible (Fig. 39B).
Specimen MB.C.22181 with 24 mm conch diameter allows the description of an intermediate growth stage. It has a discoidal and evolute conch; the whorl profi le is nearly circular with oblique umbilical wall, fl anks and venter broadly rounded (Fig. 39E). No traces of ventrolateral spiral grooves are visible.
The suture line of paratype MB.C.3628 has, at 44 mm phragmocone diameter, a general meandering outline with a high median saddle that attains more than 80 % of the external lobe depth (Fig. 40A). The prong of the E lobe as well as the shorter lateral lobe are lanceolate and weakly pouched with a pointed base. They are separated by a weakly infl ated, narrow ventrolateral saddle. There are three umbilical lobes on the fl ank; they are much shorter than the lateral lobe. The fi rst two are U-shaped and the third is small and asymmetric.

Diagnosis
Synpharciceratinae with thickly discoidal to thinly pachyconic, subevolute to evolute juvenile stage, whorl profi le depressed. Adult stage subinvolute to involute by closure of the umbilicus by shell fl ares; whorl profi le compressed, venter rounded. Adult stage without ventrolateral grooves. Suture line with wide external lobe, short bell-or funnel-shaped E 1 lobe, high median saddle, deep lanceolate E 2 lobe, smaller pointed lateral lobe, three or four outer and up to fi ve inner umbilical lobes. Suture line formula (E 2 E 1 E 2 ) L U 2 U 4 U 6 : U 5 U 3 U 1 I to (E 2 E 1 E 2 ) L U 2 U 4 U 6 U 8 : U 9 U 7 U 5 U 3 U 1 I.

Diagnosis
Stenopharciceras with thickly discoidal conch at 20 mm dm (ww / dm ~ 0.50) and thinly discoidal conch at 40 mm dm (ww / dm ~ 0.40); with very narrow to closed umbilicus. Whorl profi le slightly compressed (ww / wh ~ 0.95) at 20 mm dm and more strongly compressed at 40 mm dm (ww / dm ~ 0.75); conch widest in the midfl ank area. Flanks and venter continuously rounded. Outer suture line with bell-or funnel-shaped E 1 lobe, parallel-sided, usually pointed, E 2 , L and U 2 lobes separated by rounded saddles. Inner fl ank and umbilical wall with blunt or rounded U 4 , U 6 , U 8 and U 10 lobes.

Description
Four specimens are selected for description and illustration: Paratype MB.C.2280: rather well-preserved specimen with nearly 40 mm conch diameter in haematitic ironstone (Fig. 41A).
The material allows the study of a rather short ontogentic interval between about 20 and 40 mm conch diameter. During this interval, the conch becomes slenderer (ww / dm decreases from 0.55 to 0.40; ww / wh decreases from 1.00 to 0.70). The fl anks are convex and the venter is continuously rounded. Specimens MB.C.30254 and MB.C.2280 show a shell ornament with fi ne, widely spaced growth lines that extend with a lateral sinus and a high, linguiform ventrolateral salient across the fl anks.
The suture line of the specimens closely resemble each others. They show that, between 22 and 35 mm conch diameter, the shape of the external lobe is rather stable, but that this lobe becomes more dominant in its size during ontogeny ( Fig. 42A-D). While in holotype MB.C.30254, at 22 mm conch diameter, the lateral lobe is almost as deep as the external lobe, this proportion has shifted towards a much shorter L lobe in specimen MB.C.30255 at 35 mm diameter. The shape of the lateral lobe changes from lanceolate in holotype MB.C.30254 to tongue-shaped in paratype MB.C.30255. The E 1 lobe is bell-shaped in MB.C.30255 but V-shaped in the smaller specimens MB.C.30254 or MB.C.2280

Remarks
Stenopharciceras lotzi sp. nov. superfi cially resembles Pluripharciceras ahlburgi sp. nov. but possesses a stouter conch (ww / dm ~ 0.40 at 35 mm dm in contrast to 0.35 in P. ahlburgi sp. nov.). The main differences are in the suture line; S. lotzi sp. nov. possesses fewer, rounded lobes on the fl ank while these lobes are V-shaped in P. ahlburgi sp. nov.
Stenopharciceras lotzi sp. nov. differs from Synpharciceras clavilobum, which it closely resembles in conch shape, in the suture line which is not meandering as in S. clavilobum in the general outline. Furthermore, the E 2 lobe is lanceolate and the L and U 2 lobes are usually acute at the base, in contrast to the rounded or blunt lobes in S. clavilobum. European Journal of Taxonomy 771: 1-79 (2021) Genus Synpharciceras Schindewolf, 1940 Type species Goniatites clavilobus Sandberger & Sandberger, 1850, by original designation.

Diagnosis
Synpharciceratinae with thinly pachyconic to thickly discoidal, subevolute to evolute juvenile stage, whorl profi le depressed. Adult stage subinvolute to involute with compressed whorl profi le; venter rounded. Adult stage with or without ventrolateral grooves. Suture line with wide external lobe, short, funnel-shaped E 1 lobe, large, deep lanceolate E 2 lobe, smaller lanceolate lateral lobe, and up to 13 outer and inner umbilical lobes. Suture line formula (E 2 E 1 E 2 ) L U 2 U 4 U 6 …U 12 : U 13 …U 5 U 3 U 1 I.

Diagnosis
Synpharciceras with thinly discoidal conch at 30 mm dm (ww / dm ~ 0.45) with closed umbilicus. Whorl profi le slightly compressed (ww / wh ~ 0.95); conch widest near the umbilicus. Flanks and venter continuously rounded; venter bordered by faint ventrolateral spiral grooves. Outer suture line with weakly pouched, blunt, E 2 , L and U 2 lobes meandering with separating rounded saddles. Inner fl ank and umbilical wall with blunt U 4 , U 6 , U 8 and U 10 lobes.

Description
Holotype 42 in the Wiesbaden Museum is a rather well-preserved, partly exfoliated specimen with 32 mm diameter, at which the conch dimensions can be obtained at 29 mm diameter (Fig. 43). It is thinly discoidal (ww / dm = 0.48) with an almost closed umbilicus, but this area is obscured by matrix. The whorl profi le is weakly compressed (ww / wh = 0.93); it is widest near the umbilicus, from where the convex fl anks converge towards the continuously rounded venter. On the venter, there are two weak spiral grooves standing 4 mm apart. The suture line of the specimen shows a meandering outline with weakly pouched E 2 , L and U 2 lobes similar in outline; they are rounded at the base (Fig. 45A). They are separated by rather narrow, rounded saddles.

Remarks
Synpharciceras clavilobum is a rare species; only a few characteristic specimens are known from the type region. It differs from the more common species Pluripharciceras ahlburgi sp. nov. in the shape of the whorl profi le, which in S. clavilobum is widest near the umbilicus but in P. ahlburgi sp. nov. widest in the midfl ank area. Furthermore, S. clavilobum has a conspicuously meandering suture line, while in P. ahlburgi sp. nov. the lobes are acute.
A species similar in conch shape is Stenopharciceras lotzi sp. nov., but this species differs in the suture line. The general outline of the suture line in that species is not meandering as in S. clavilobum, the E 2 lobe is lanceolate and the L and U 2 lobes are usually acute at the base, in contrast to the rounded or blunt lobes in S. clavilobum.
The shape of the whorl profi le is also a separating character to distinguish the material from the type region from North African material that has been identifi ed as S. clavilobum (Petter 1959;Bensaïd 1974;Bockwinkel et al. 2009Bockwinkel et al. , 2013a. As shown in the latter monographic articles, the conch is, in the specimens from the Anti-Atlas, widest in the midfl ank area, from where   Tables 28-29 Pharciceras clavilobum -Wedekind 1918: 127, pl. 20 fi gs 4-5, text-fi g. 37d.

Diagnosis
Pluripharciceras with thinly discoidal conch at 20 mm dm (ww / dm ~ 0.40) and extremely discoidal conch at 40 mm dm (ww / dm ~ 0.30); with very narrow to closed umbilicus. Whorl profi le slightly compressed (ww / wh ~ 0.90) at 20 mm dm and weakly compressed at 40 mm dm (ww / dm ~ 0.60); conch widest in the midfl ank area. WER moderate to high. Flanks and venter continuously rounded; venter narrowly rounded. Outer suture line with parallel-sided, usually pointed, E 2 , L and U 2 lobes meandering with separating saddles. Inner fl ank and umbilical wall with acute U 4 , U 6 , U 8 and U 10 lobes.

Etymology
Named after Johannes Ahlburg (1883-1919), who assembled a collection of Roteisenstein fossils including the type of the new species.

Remarks
Pluripharciceras ahlburgi sp. nov. differs from Synpharciceras clavilobum in the shape of the whorl profi le, which in P. ahlburgi sp. nov. is widest in the midfl ank area but in S. clavilobum is widest near the umbilicus. Furthermore, S. clavilobum has a conspicuously meandering suture line, while in P. ahlburgi sp. nov. the lobes are V-shaped and acute.

Diagnosis
Triainoceratidae with eight to twelve umbilical lobes.   (2021) well-preserved. It allows an insight into the conch ontogeny from the initial stage to the adult stage. Up to about 18 mm diameter, the conch is very evolute; thereafter, the whorl begins to grow in height and the relative width of the umbilicus decreases. At 15 mm diameter, the whorls are broadly kidney-shaped in profi le and the venter is broadly rounded. At about 30 mm diameter the whorls are already much higher and at about 45-50 mm diameter apparently already compressed-triangular with a very narrow venter. The inner whorls are apparently unsculptured, but at about 10 mm diameter sharp, initially closely spaced ribs appear; at about 12 mm diameter there are about eight ribs on a quarter whorl. The ribs are present up to a conch diameter of 30 mm; they run almost straight across the fl ank.
SMF.Mbg.6360: incomplete, slightly distorted specimen of about 75 mm conch diameter in iron-rich limestone with shell remains preserved (Fig. 50C) The suture line shows, at a whorl height of 15.5 mm, a Y-shaped, divided external lobe with very narrow, ventrally somewhat pouched prongs and a median saddle reaching half the height of the lobe (Fig. 51B). The ventrolateral saddle is rounded and slightly tilted in the dorsal direction. The lateral lobes are deep and infl ated, with a mammiform base. Two more, V-shaped and much smaller umbilical lobes follow on the fl ank. On the inner fl anks and the umbilical wall no portion of the suture line is preserved, but it is likely that more lobes would follow.

Remarks
With the decision of the International Commission of Zoological Nomenclature (1956), at the request of Miller (1952), the species Sandbergeroceras sandbergerorum was declared an objective synonym of S. tuberculosocostatum. This decision was apparently unknown to House (in House & Ziegler 1977), so that he considered S. sandbergerorum valid and designated the Wiesbaden specimen as lectotype. This specimen is determined here as the lectotype of S. tuberculosocostatum.
The suture line shown here signifi cantly differs from the illustration of Sandberger & Sandberger (1850-1856 fi g. 1f), which had been copied several times (Foord & Crick 1897;Miller 1938;Bogoslovsky 1969;. The reason for this difference could be that the latter specimen has been cut too deeply and therefore some features have been lost; the illustrations of specimens as well as suture lines are usually excellent and very accurate in this monograph. The suture line shown here (Fig. 51B) is similar to the one published by Bogoslovsky (1969) for "Triainoceras gerassimovi". However, that species has only two lobes on the fl ank, the somewhat pouched, V-shaped lateral lobe and a somewhat smaller, V-shaped umbilical lobe. Because of this somewhat simpler suture line with fewer elements, the species became the type species of Altayites .
Although the material is incomplete and not well preserved, the species can be reasonably well defi ned. One problem, however, could be that the specimens do not belong to the same species. Sandbergeroceras tuberculosocostatum differs from S. costatum in the form of the whorl profi le. This is much slenderer in S. tuberculosocostatum (ww / wh ~ 1.10 in comparison to ~ 1.30 in S. costatum). Furthermore, the whorl profi le begins to fl atten with a subacute venter already at about 30 mm conch diameter in S. tuberculosocostatum, while the venter is still rounded in S. costatum.

Remarks to the type material
The whereabouts of the original material is not known. The specimen illustrated by d'Archiac & de Verneuil (1842: pl. 36 fi g. 1) does not exist in the de Verneuil collection at the University of Lyon, where other original specimens of this work are located (Emmanuel Robert, written comm., April 8 th , 2021). However, the description and illustration by d' Archiac & de Verneuil (1842) allows the species to be characterised (Fig. 53). The only available specimen MB.C.7695 corresponds well with the one illustrated by d' Archiac & de Verneuil (1842), in conch form as well as sculpture and suture line. It can therefore, with little doubt, be considered conspecifi c. It is herewith proposed as the neotype of the species.
Description MB.C.7695: incomplete, somewhat distorted specimen of about 42 mm conch diameter in iron-rich limestone (Fig. 50B). Although somewhat deformed laterally, it allows the study of conch geometry and ontogenetic development. At 33 mm diameter, the conch is discoidal and subevolute (ww / dm ~ 0.45, uw / dm ~ 0.40) with a broad pear-shaped whorl profi le (ww / wh ~ 1.30), which is widest in the middle of the fl anks. The umbilical edge is rounded; the external side has a rounded keel accompanied by European Journal of Taxonomy 771: 1-79 (2021) shallow longitudinal grooves. The interior whorls are poorly preserved and do not allow any study of the ornament. The last one and one-half whorls possess sharp ribs, which initially extend with a concave curve, then straight and fi nally with a slightly convex curve over the fl ank. The penultimate whorl shows sharp growth lines with the same course as the ribs.
Only a short portion of the suture line is visible in the ventral area. The external lobe is parallel-sided with a median saddle that reaches about half the height of the lobe. The E 1 lobe is very narrow and very deep (Fig.51A).

Remarks
Sandbergeroceras costatum differs from S. tuberculosocostatum in the form of the whorl profi le, which is much stouter in S. costatum (ww / wh ~ 1.30 in comparison to ~ 1.10 in S. tuberculosocostatum). The whorl profi le begins to fl atten with a subacute venter already at about 30 mm conch diameter in S. tuberculosocostatum, while the venter is still rounded at this diameter in S. costatum.
The main difference to S. archiaci sp. nov. is that the ventrolateral grooves are less pronounced in S. costatum. The umbilicus is, at a comparable diameter, narrower in S. costatum (ww / dm ~ 0.40 in S. costatum but ~ 0.50 in S. archiaci sp. nov.).  Table 32 Diagnosis Species of Sandbergeroceras with thinly discoidal, evolute conch at 30 mm dm (ww / dm ~ 0.35; uw / dm ~ 0.50). Whorl profi le moderately depressed (ww / wh ~ 1.55); venter fl atly rounded. Two deep spiral grooves on the venter. Shell ornament with 30 sigmoidal, sharp ribs on the fl anks and coarse growth lines.

Etymology
Named after Étienne Jules Adolphe Desmier de Saint-Simon, Vicomte d'Archiac (1802-1868), one of the pioneers of studying fossils from the Red Ironstone.

Description
Holotype MB.C.3671 is an incomplete, but rather well-prerserved specimen of 33 mm conch diameter in fossil-rich and iron-rich limestone (Fig. 50A). It allows the study of slightly more than two whorls up to a conch diameter of 33 mm. The conch is discoidal and evolute (ww / dm = 0.35; uw / dm = 0.51) with low coiling rate (WER = 1.51); the whorl profi le depressed (ww / wh = 1.56) with continuously rounded umbilical wall, fl anks and venter. The venter bears two rather deep spiral grooves. Both whorls bear rounded, forward-directed ribs; there are 30 such ribs on the last whorl and 40 on the penultimate. In addition, sharp growth lines are formed at almost equal intervals of about 0.2 mm. They extend almost straight across the fl ank and curve forward to a moderately high projection in the ventrolateral area.

Remarks
Sandbergeroceras archiaci sp. nov. differs from S. tuberculosocostatum and S. costatum in the form of the whorl profi le and the umbilical width. The whorl profi le is rounded-triangular with a tightly rounded venter in the latter two species, whereas the venter is weakly fl attened in S. costatum. The ventrolateral grooves are less pronounced in S. tuberculosocostatum and S. costatum. The umbilicus is, at 30 mm conch diameter, wider in S. costatum (ww / dm ~ 0.50 in S. costatum but only ~ 0.40 in S. tuberculosocostatum and S. costatum).

Discussion
The mining of the red ironstone of Dillenburg can be regarded as the cradle of the investigation of late Middle Devonian and early Late Devonian ammonoids. Already in the 19 th century (von Buch 1832; Beyrich 1837a; d'Archiac & de Verneuil 1842; Sandberger & Sandberger 1850-1856 and at the beginning of the 20 th century (Wedekind 1918), numerous species were described; however, the palaeontological study of these fossils experienced a long interruption thereafter, parallel to the slow decline of mining. Only with the study of time-equivalent assemblages from the Anti-Atlas of Morocco (Petter 1959;Bensaïd 1974;Bockwinkel et al. 2009Bockwinkel et al. , 2013a and various localities in the Rhenish Mountains (Bockwinkel et al. 2013b;Bockwinkel & Korn 2015) did awaken the interest in re-describing and revising the fossils from the original sites.
In a fi rst step of the revision, we present here the redescription of the ammonoids from the suborder Pharciceratina. A total of 20 species are described. All belong to genera that are also known from other regions; the greatest similarity at the generic level is to the Anti-Atlas of Morocco. However, there is apparently no agreement concerning the species.