Journal of the Czech Geological Society 46/3ñ4(2001) 131

On the genus Acrospirifer Helmbrecht et Wedekind, 1923 (Brachiopoda, Lower Devonian) (Contributions to Lower Devonian brachiopods from the Rheinisches Schiefergebirge and adjacent areas, 1)

O rodu Acrospirifer Helmbrecht et Wedekind, 1923 (Brachiopoda, spodnÌ devon)

(3 plates)

ULRICH JANSEN

Forschungsinstitut Senckenberg, Senckenberganlage 25, 60325 Frankfurt am Main, Germany

Numerous Devonian spiriferid species with strongly plicate shells distributed almost worldwide have been assigned to the taxon Acrospirifer Helmbrecht et Wedekind, 1923. In order to prepare a revised diagnosis for the genus, materials of the type species A.†primaevus (Steininger, 1853) from its regio typica (Rheinisches Schiefergebirge, Germany) are redescribed. Well-preserved specimens display a fimbriate micro- ornamentation, with minute spines along the margins of concentric growth lamellae. This observation contradicts the diagnosis of the genus published by Gourvennec (1989) and the diagnosis of the family Acrospiriferidae Termier et Termier, 1949 published by Carter et al. (1994); both diagnoses include as a main character a capillate micro-ornamentation lacking minute spines. Due to the new observations, the diagnosis of the genus Acrospirifer is revised. The taxonomic position of different species up to now assigned to the genus is discussed. According to the present knowledge, Acrospirifer is restricted to its type species probably only occur- ring in the Ardenno-Rhenish Mountains (? southern England, ? Czech Republic). In the Lower Devonian of West Europe and North Africa purely capillate forms are abundant which have hitherto been determined as Acrospirifer; Gourvennecís diagnosis was also based on these forms. They do not belong to Acrospirifer but to the genus Filispirifer Jansen, 2001 comprising the group of ìSpiriferî fallax Giebel, 1858. This group also occurs in the Lower Emsian Erbsloch-Grauwacke and in Hercynian Limestones (Kellerwald and Harz Mountains, Germany). It is concluded that previous determinations of Acrospirifer or even A. primaevus in West Europe and North Africa should be reconsidered, and also stratigraphical alignments based on these determinations. At last, the family Acrospiriferidae can hardly be maintained in its present definition.

Key words: Brachiopoda, Spiriferida, Palaeozoic, Lower Devonian, stratigraphy, Rheinisches Schiefergebirge, Germany

Introduction without plications, sinus generally lacking plications but in some species with faint median costa; ventral muscle In the Lower Devonian of the Rheinisches Schieferge- field impressed; dental plates thickened, more or less birge (= Rhenish Slate Mountains, Germany), brachio- embedded in secondary shell thickenings. Maillieux re- pods represent a very abundant and diverse group of garded Euryspirifer Wedekind, 1926 (= paradoxus- macrofossils. The biostratigraphical subdivision of the group) and Paraspirifer Wedekind, 1926 (= cultrijuga- Rhenish Lower Devonian has mainly been based on ar- tus-group) as junior synonyms of Acrospirifer. From the ticulate brachiopods (see e.g. Mittmeyer 1982). In spite present viewpoint, the range of the taxon was certainly of their high biostratigraphical potential, not many de- too wide. As we know today, plicate spiriferids with tailed systematic descriptions have been published up to smooth sulcus and fold and with impressed ventral mus- now. This paper is the first one of an intended series deal- cle field rather represent a certain ecological morphotype ing with Rhenish Lower Devonian brachiopods. In this adapted to turbid waters and sandy sedimentation, but work, the genus Acrospirifer is considered, starting from they are not a natural phylogenetic unit. In a later publi- a re-study of its type species A.†primaevus (Steininger, cation, Maillieux (1941) distinguished between Acrospiri- 1853) which is a classical index fossil for the Middle to fer and Paraspirifer and regarded them as subgenera of Upper Siegenian in the Rheinisches Schiefergebirge. Hysterolites von Schlotheim, 1820. The genus Acrospirifer has been erected by Helm- In general, many coarsely costellate or plicate species brecht ñ Wedekind (1923) who did not give a diagnosis occurring worldwide in Lower to Middle Devonian stra- but only mentioned the group of the species ìSpiriferî ta have been determined as Acrospirifer since the 1930ís. primaevus Steininger, 1853 and named it Acrospirifer. In an atlas of North American index fossils, Cooper The authors included ìSpiriferî primaevus and ìS.î dech- (in Shimer ñ Shrock 1949) published a diagnosis resem- eni Kayser, 1878 (= fallax Giebel, 1858) in the genus, bling that of Maillieux: ìsubsemicircular to transversely and a new species which they named septalis. semielliptical, costate and lamellose spiriferoids; fold and Wedekind (1926, p. 202) designated ìSpiriferî pri- sulcus noncostate, dental plates strong, muscular field maevus as the type species of the genus. Maillieux (1931, large, elongate-oval; dorsal interior with thick socket p. 36) classified Acrospirifer as a subgenus of Spirifer platesî. and included species in the subgenus which share follow- In his monograph on the arduennensis-intermedius- ing features: simple and generally strong plications, fold group, Solle (1953) maintained a rather wide concept of

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Acrospirifer which he regarded as a subgenus of Hyster- arduennensis and concluded that this group had to be olites. Characters of his preliminary diagnosis were de- separated from Acrospirifer. Therefore, he classified the tails of the shell form, impressed ventral muscle field, arduennensis-group as a new subgenus of Hysterolites reduced dental plates, and a micro-ornamentation con- but did not give it a name. taining micro-spines (= ìpapillaeî; however, it is not sure Mittmeyer (1972) erected for the arduennensis-inter- whether Solle considered material of the type species). medius-group the new subgenus Acrospirifer (Arduspiri- Solle included the whole arduennensis-intermedius-group fer) and later (1973b) elevated it to a separate genus. in Hysterolites (Acrospirifer). According to Mittmeyer (1973a), Acrospirifer (including HavlÌËek (1959) also included the arduennensis-inter- Arduspirifer) shows a micro-ornamentation consisting of medius-group and the paradoxus-group in Acrospirifer. rows of long micro-spines (ìMikro-Dornenî). He as- His diagnosis was quite differentiated containing apical sumed that capillae (ìMikro-Rippenî) in Acrospirifer pri- characters and details of the micro-ornamentation, which maevus were probably a result of abrasion. Mittmeyer he described as fimbriate. (1973b) united species with purely capillate and with Vandercammen (1963) revised the Devonian spirifer- fimbriate micro-ornamentation in Acrospirifer. ids of Belgium including the genus Acrospirifer. The type Considering only specimens from the Armorican Mas- of micro-ornamentation and apical characters were used sif, Gourvennec (1989, p. 60ñ61) published a revised di- to distinguish between genera. Vandercammen investigat- agnosis of Acrospirifer including a purely capillate mi- ed Acrospirifer primaevus and observed the presence of cro-ornamentation and lacking notothyrial platform as capillae (ìmicrocostulesî) terminating as a fringe of the most important characters. Gourvennec believed that minute spine bases over the anterior margin of each the minute spines in A.†primaevus described by Vander- growth lamella, so that the micro-ornamentation of the cammen (1963) were just a fallacious impression caused species was considered to be essentially fimbriate. How- by ìperturbationsî of the capillae at the passage from one ever, Vandercammen also included the purely capillate growth lamella to the next one. species ìSpiriferî beaujeani BÈclard, 1887 and ìS.î sol- Subsequently, Carter et al. (1994), preparing the itarius Krantz, 1857 (today the type species of Multispiri- spiriferid part of the new brachiopod volume of the fer Kaplun, 1961) in Acrospirifer. Vandercammen recog- ìTreatise on invertebrate Paleontologyî, revised the di- nized the differences in micro-ornamentation but agnosis of the family Acrospiriferidae Termier et Termi- obviously he did not consider them as very substantial. er, 1949. The family diagnosis included as a main char- Apparently, he was also misled by a capillate specimen acter a capillate micro-ornamentation without from the Armorican Massif (Vandercammen 1963, Pl. 2, micro-spines. Acrospirifer was put in a subfamily Fig. 11) which he determined as A.†primaevus. Further Acrospiriferinae, together with the purely capillate gen- diagnostic characters were an excavated ventral muscle era Mauispirifer and Xerospirifer. A capillate family field and lacking crural plates. A similar diagnosis of Acrospiriferidae was maintained by Bizzarro ñ Acrospirifer was published by Pitrat (1965) in the bra- LespÈrance (1999) in a cladistic analysis but, in addition, chiopod volume of the ìTreatise on invertebrate Paleon- the Mucrospiriferinae have been included in the family. tologyî. Euryspirifer and Paraspirifer were definitely These workers even presented the capillate micro-orna- accepted as separate genera. mentation as the only diagnostic character of the family. In several publications (e.g. Amsden ñ Ventress 1963, Johnson (1995) erected the genus Patriaspirifer in- Johnson 1970, Boucot 1973), North American species cluding the North American species Patriaspirifer kobe- like e.g. ìSpiriferî murchisoni Castelnau, 1843, ìS.î at- hana (Merriam, 1940) and P. murchisoni (Castelnau, lanticus Clarke, 1907, and ìS.î kobehana Merriam, 1940 1843) which had been regarded as species of Acrospiri- were assigned to Acrospirifer. fer before. The main character Johnson used to distin- îSpiriferî fallax Giebel, 1858 from Lower Emsian guish the North American genus from Acrospirifer was Hercynian Limestones and the Erbsloch-Grauwacke the presence of a fimbriate micro-ornamentation. (Kellerwald and Harz Mountains, Germany) has for a My investigation of Acrospirifer primaevus (Steininger, long time been regarded as a species of Acrospirifer be- 1853) from the type region (northern Rheinisches Schief- ing very closely related to A.†primaevus (see e.g. Mitt- ergebirge) has largely confirmed Vandercammenís (1963) meyer 1973b, p. 20). Jahnke (1971) described fallax as observations. This has taxonomic consequences described a species of Acrospirifer supposing that primaevus was below. Further, the new results are important with respect the phylogenetic forerunner of fallax. The author ob- to stratigraphical and palaeobiogeographical consider- served that primaevus ñ in contrast to fallax ñ is charac- ations. The main facts have already been presented on the terized by the presence of strongly developed plications ìMillenium Brachiopod Congressî in London (Jansen bounding the sulcus, a thick dorsal median process 2000) and in a monograph (Jansen 2001). In the follow- (ìmyophragmaî in Jahnke), and a well-developed no- ing systematic part, the genus Acrospirifer and its type spe- tothyrial platform (ìKardinalplateauî). In fallax, he de- cies are briefly described. The type-species contains dif- scribed a purely capillate micro-ornamentation. Jahnke ferent morphotypes which may be distinguished as recognized a fimbriate micro-ornamentation in ìSpiriferî different subspecies in the future. A more detailed descrip-

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tion also containing information on intraspecific variation al platform present, in general moderately to strongly de- and palaeobiology is planned by the author. veloped, in rare cases poorly developed. Dorsal adductor In this work, the classical subdivision of the Lower field impressed, commonly divided by a strong median Devonian into the stages Gedinnian ñ Siegenian ñ Em- process in its posterior part. Free crural bases hardly pro- sian is used, as it has been defined in Germany. This sub- nounced. Free crural plates and outer hinge plates absent. division retains value in the Rheinisches Schiefergebir- Species assigned: At present, only the type spe- ge because the international subdivision defined by cies A. primaevus is assigned to the genus with certainty GSSPs still cannot be exactly reproduced here. (see below). Discussion: In the last three decades, mainly follow- Systematic paleontology ing species have been assigned to Acrospirifer: A. pri- maevus (Steininger, 1853), ìA.î fallax (Giebel, 1858), Order Spiriferida Waagen, 1883 ìA.î beaujeani (BÈclard, 1887), ìA.î kobehana (Merri- Suborder Delthyridina Ivanova, 1972 am, 1940), and ìA.î murchisoni (Castelnau, 1843). The Superfamily Delthyridoidea Phillips, 1841 latter two species from North America have already been Family Hysterolitidae Termier et Termier, 1949 excluded from the genus by Johnson (1995) who erect- Subfamily Hysterolitinae Termier et Termier, 1949 ed the new genus Patriaspirifer for them. The diagnosis of the genus Acrospirifer published by Genus Acrospirifer Helmbrecht et Wedekind, 1923 Gourvennec (1989) included as main characters a capil- late micro-ornamentation and a lacking notothyrial plat- Type species: Spirifera primaeva Steininger, 1853 form. However, Gourvennec exclusively referred to ma- terial from the Armorican Massif (western France). He *pt 1923 Acrospirifer Helmbrecht et Wedekind, p. 952. described the species primaevus Steininger, 1853 and pt 1931 Sous-genre Acrospirifer. ñ Maillieux, p. 47. pt 1935 Acrospirifer. ñ Allan, p. 18. fallax Giebel, 1858. Subsequently, Johnson (1995) and pt 1941 Sous-genre Acrospirifer. ñ Maillieux, p. 51. Bizzarro ñ LespÈrance (1999) also assumed a capillate pt 1949 Acrospirifer. ñ Cooper, in Shimer ñ Shrock, p. 323. micro-ornamentation in Acrospirifer and draw further pt 1953 Untergattung Acrospirifer. ñ Solle, p. 29. systematic conclusions. pt 1959 Hysterolites (Acrospirifer). ñ HavlÌËek, p. 98ñ99, 237. pt 1963 Acrospirifer. ñ Vandercammen, p. 5ñ6. From my own observations and from literature I am pt 1964 Acrospirifer. ñ Drot, p. 45. sure, that many well-preserved specimens from the pt 1965 Acrospirifer. ñ Pitrat in Moore (Ed.), p. H 681ñ682. Kellerwald Mountains (eastern Rheinisches Schieferge- pt 1973 Acrospirifer. ñ Mittmeyer, p. 38. ñ [1973a]. birge, see Jahnke 1971), the Anti-Atlas Mountains (south- pt 1973 Acrospirifer. ñ Mittmeyer, p. 88ñ89. ñ [1973b]. non1989 Acrospirifer. ñ Gourvennec, p. 60ñ61. ñ [=Filispirifer]. ern Morocco, see Jansen 2001), the Celtiberian Chains 2001 Acrospirifer. ñ Jansen, p. 285. (northeastern Spain, collection Carls), and the Armori- can Massif (see Gourvennec 1989) which have hitherto Stratigraphical distribution: According to the present been determined as Acrospirifer are in full accordance knowledge, the genus is confined to the Middle to Upper Siege- nian (? lower Lower Emsian). with Gourvennecís diagnosis. The typical capillate mi- Geographical distribution: At present, Acrospirifer is re- cro-ornamentation is figured by Jahnke (1971, Pl. 6, stricted to its type species occurring in the Ardenno-Rhenish Moun- Fig. 10) and Gourvennec (1989, Pl. 3, Fig. 13). tains and probably in southern England and the Hrub˝ JesenÌk However, the re-investigation of the type-species Mountains (Czech Republic). Reports of occurrences in other re- gions have already proved to be incorrect, or they are at least doubt- Acrospirifer primaevus (Steininger, 1853) from the type ed (see below, under ìdiscussionî). region in the Rheinisches Schiefergebirge has shown that this species is characterized by a fimbriate micro-orna- Revised diagnosis: (from Jansen 2001) large and mentation and a well-developed notothyrial platform (see strongly biconvex, pauciplicate hysterolitines. Shells semi- below). According to my own experiences in delthyridoid circular to somewhat transversely semielliptical in outline, brachiopods, I feel that the type of micro-ornamentation with simple, very strong and angular plications; number is an important generic character because it remains rath- of these generally ranging from 8 to 12 on each flank. Pli- er stable within a genus. Therefore, it was necessary to cations bounding the sulcus are strong, generally not weak- erect again a new diagnosis for the genus Acrospirifer. ened and not situated on a lower level with respect to the In some of the Acrospirifer-like specimens with capil- adjacent plications; only in rare cases they are weakened late micro-ornamentation from the Kellerwald and the and included in the sulcus. Sulcus with median costa. Mi- Anti-Atlas Mountains which I have studied small nod- cro-ornamentation of the fimbriate type, with a fringe of ules are visible where the concentric growth lines resp. rod-like micro-spines over each growth lamella; micro- lamellae cross the capillae. These nodules could be in- spines are of subequal size. Deltidial lamellae poorly de- terpreted as reduced spines. However, the nodules are veloped. Secondary shell in the apical regions of both different from the spines in A.†primaevus because they valves very thick. Subdelthyrial plate absent. Ventral mus- are never really free projections over the growth lamel- cle field deeply impressed. Dental plates largely embed- lae. Even in very well-preserved specimens, I have not ded in apical shell thickenings in adult stages. Notothyri- seen real spines like in A.†primaevus. This is the same

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condition Gourvennec (1989, p. 64ñ65) observed in In contrast to Acrospirifer primaevus, specimens of the ìAcrospirifer primaevusî from the Armorican Massif. capillate genus Filispirifer (= the fallax-group) I have The Acrospirifer-like but capillate shells without mi- seen are characterized by a lacking or poorly developed cro-spines from West Europe and North Africa (common- notothyrial platform, as also observed by Gourvennec ly determined as fallax or primaevus) certainly do not be- (1989) in his Armorican specimens. Only in rare cases, the long to Acrospirifer but to the genus Filispirifer Jansen, platform can be almost as strong as in A.†primaevus. In 2001. This genus encompasses the group of ìSpiriferî addition, the plications bounding the sulcus are generally fallax Giebel, 1858 mainly distributed in the Mauro-Ibe- weaker than the adjacent second plications and included ro-Armorican region. This region is regarded as a part of in the sulcus. In A.†primaevus, the plications bounding the former North Gondwana, whereas the Ardenno-Rhenish sulcus are mostly as strong as the adjacent plications. Con- region is considered to belong to the Old Red Continent cerning the other morphological characters, there are close (e.g. Robardet et al. 1990). The presence of ìSpiriferî similarities. fallax in the Erbsloch-Grauwacke and in Hercynian Lime- I am not sure about the taxonomic importance of the stones (Kellerwald and Harz Mountains, Germany) is observed differences. In spite of these, close phylogenet- probably due to tectonic transport of these rocks from ic relationships appear to be possible. At present, the dif- Gondwana to the North. Other faunal elements in the ferences are regarded as relevant on the generic level only. Erbsloch-Grauwacke (Lower Emsian, Kellerwald Moun- On the other hand, the ìAcrospirifer morphotypeî could tains) support close palaeobiogeographical relationships have developed in completely separate phylogenetic lin- to North Gondwana, e.g. the tabulate corals (Plusquellec eages and may represent a special ecological morphotype. ñ Jahnke 1999). I have investigated specimens of ìSpiri- Further research may elucidate the true phylogenetic re- ferî fallax from the Erbsloch-Grauwacke, and these clear- lationships between the forms under consideration. ly exhibit a purely capillate micro-ornamentation. How- Acrospirifer primaevus is a classic index fossil for the ever, it cannot be excluded that the special facies Middle to Upper Siegenian in the Ardenno-Rhenish conditions being of mixed Rhenish-Hercynian type are the Mountains, ìAcrospiriferî fallax (Giebel, 1858) an index reason for the presence of this species. fossil for the lower Lower Emsian (see e.g. Carls et al. In contrast to previous opinions (e.g. Vandercammen 1982, Fuchs 1982, Mittmeyer 1982). Specimens assigned 1963; Carls, in Brice et al. 2000), ìSpiriferî beaujeani to Acrospirifer have been used for stratigraphical align- BÈclard, 1887 from Siegenian strata of Belgium is not ments in West Europe and North Africa as well. If these an Acrospirifer either. I have investigated the holotype forms do not belong to Acrospirifer, what seems to be at that exhibits very clearly a capillate micro-ornamentation. least frequently the case, the drawn stratigraphical con- The ventral muscle field of another specimen is hardly clusions are problematic, of course. Moreover, the forms inpressed. The generic assignment of this rare species determined as ìAcrospirifer fallaxî from the lowest Em- remains uncertain; perhaps it belongs to Filispirifer Jan- sian (Ulmen Group) of the Eifel region (Mittmeyer 1982, sen, 2001 or it is a member of another (? new) genus. If Fuchs 1989) are probably descendants of Acrospirifer it actually belongs to Filispirifer, it would mean that this primaevus and may have nothing to do with fallax. genus sporadically occurs in the Ardennes. Further, the results of this work have also consequenc- Occurrences of ìAcrospiriferî have been reported es on palaeobiogeographical considerations: Acrospirifer from following North Gondwanan regions: Armorican is not available any further as a reliable witness for very Massif (Renaud 1942, Gourvennec 1989), Pyrenees (La- close affinities between Ardenno-Rhenish and Mauro- verdière 1930), Cantabrian Mountains (Jahnke et al. Ibero-Armorican faunas. The observed differences rath- 1983, GarcÌa-Alcalde et al. 1990), Celtiberian Chains er support the assumption that there was an oceanic bar- (Carls 1987, 1999, Carls ñ Valenzuela-RÌos 1998; Carls, rier between Gondwana and Euramerica in middle and in Brice et al. 2000), Anti-Atlas Mountains (Drot 1964), late Early Devonian times, restricting the faunal migra- northwestern Sahara (Le MaÓtre 1952a), and Ougarta tion between the shelf regions of the continents. Chains (Le MaÓtre 1952b; Gourvennec, in Boumendjel In the context of the revision of Acrospirifer, the North et al. 1997). These materials should be re-evaluated, and American genus Patriaspirifer Johnson, 1995 must be con- special attention must be paid to the micro-ornamenta- sidered as well. The genus contains the two species kobe- tion. I have a strong suspicion that many or even all these hana Merriam, 1940 and murchisoni Castelnau, 1843 specimens will turn out to be purely capillate. which had been included in Acrospirifer before Johnsonís One could argue that it is not a very big evolutionary publication in 1995. After Johnson (1995), Patriaspirifer step from the one type of micro-ornamentation to the oth- is distinguished from Acrospirifer by the presence of a fim- er type. In the course of phylogenetic development, mi- briate micro-ornamentation. Bizzarro ñ LespÈrance (1999, cro-spines were probably reduced to small nodules or, the p. 1062) accordingly stated: ìThe most significant differ- other way round, nodules were extended to micro-spines. ence between Patriaspirifer and Acrospirifer lies in the Perhaps, even environmental factors had a minor influ- micro-ornament. Spirifer primaevus Steininger, 1853, the ence on this. In any case, the difference between capil- type species of Acrospirifer, has a spine-less micro-orna- late and fimbriate condition is present and certainly of ment consisting of capillae, while North American forms taxonomic relevance. possess a fimbriate micro-ornamentÖî.

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Johnson, Bizzarro, and LespÈrance are wrong in this Acrospirifer is characterized by the strongest and most point. Because Acrospirifer primaevus has a fimbriate mi- angular plications. cro-ornamentation, this difference does not exist. How- Euryspirifer Wedekind, 1926 is regarded as being ever, shells determined as species of Patriaspirifer pos- closely related to Acrospirifer. However, the shells are sess considerable free lamellae along the inner socket alate in outline and multiplicate, the plications being ridges in the apical region of the dorsal valve (e.g. weaker. On the other hand, the genus shares some of the Johnson 1970, Pl. 56, Fig. 9, Pl. 58, Fig. 17; Amsden ñ diagnostic features with Acrospirifer: profile strongly bi- Ventress 1963, Pl. 6, Fig. 2) which may be called outer convex, median costa in the sulcus present, similar mi- hinge plates. Such lamellae are absent in Acrospirifer pri- cro-ornamentation, dental plates largely embedded in maevus. In this species, there are only very little pro- apical shell thickenings, ventral muscle field deeply im- nounced crural bases representing the free parts of the pressed, notothyrial platform present, median process crura which are included in the articulation apparatus. present, bisecting the impressed dorsal adductor field. Therefore, it seemingly still makes sense to maintain the Therefore, a close phylogenetic relationship between the North American genus Patriaspirifer. two genera is assumed. The North American species ìSpiriferî atlanticus Hysterolites von Schlotheim, 1820 has smaller shells Clarke, 1907 was assigned to Acrospirifer by Boucot and a different micro-ornamentation; median costa in (1973). Because the species is characterized by more the sulcus absent; ventral muscle field not impressed; transverse shells and more numerous and weaker plica- free dental plates are long and thin; free crural bases tions than Acrospirifer I prefer to assign it to the genus are more developed. Brachyspirifer Wedekind, 1926 is Euryspirifer. characterized by more ribs, not impressed ventral mus- Benedetto (1984) determined Acrospirifer in the Low- cle field, longer free dental plates, and crural bases er Devonian of Venezuela. The specimens determined as embedded to a lower degree in shell thickenings. ìAcrospirifer macrothyris (Hall, 1867)î do not belong to Paraspirifer Wedekind, 1926 has more ribs which are Acrospirifer. They have much weaker plications and a finer and tend to bifurcate. Arduspirifer Mittmeyer, different micro-ornamentation (cf. Benedetto 1984, 1972 is discriminated from Acrospirifer by smaller Pl. 19, Fig. 10). The specimens assigned to ìAcrospiri- shells and a slightly different micro-ornamentation with fer cf. murchisoni (Castelnau, 1843)î do not belong to micro-spines being more variable in size within the con- Acrospirifer either because of their smaller size and dif- centric rows. A median costa in the sulcus is generally ferent micro-ornamentation. absent (except for A.†mosellanus where a faint median Recently, Chen ñ Yao (1999) described a Chinese fau- costa may be present). na and erected the species shipengensis which they de- Dixonella Gourvennec, 1989 is smaller and has no termined as Acrospirifer. However, the description does median process separating the dorsal adductor field. The not give enough information to be sure to which genus plications bounding the sulcus are weakened and situat- the species belongs. In general, I would hesitate to de- ed on a lower level than the adjacent second plications. termine Ardenno-Rhenish brachiopod genera in China. Apart from that, this genus is very similar to Acrospiri- According to the present knowledge, the genus fer. Occurring in the Lower Siegenian of West Europe Acrospirifer should be restricted to its type species and North Africa, Dixonella is older than Acrospirifer and A. primaevus that probably occurs exclusively in the could be the phylogenetic forerunner. Ardenno-Rhenish region and possibly in southern England Torosospirifer Gourvennec, 1989 from the Siegenian and the Czech Republic. Previous assignments of other of Spain and France, erected as a subgenus of Brachy- species to this genus are regarded as doubtful and should spirifer, is regarded as a separate genus here. It is dis- be carefully reconsidered. Reports of Acrospirifer outside criminated from Acrospirifer by more and finer ribs and the Ardenno-Rhenish Mountains are doubted. considerable free crural bases (ìlamelles apicales dor- At last, Acrospirifer is the type genus of the family salesî sensu Gourvennec; ? outer hinge plates) along the Acrospiriferidae Termier et Termier, 1949. Carter et al. inner socket ridges; such free lamellae are absent in (1994) published a revised family diagnosis which shall Acrospirifer; free dental plates are generally longer in also be published in the forthcoming spiriferid part of the Torosospirifer (cf. Gourvennec 1989). ìTreatise on Invertebrate Paleontologyî. The main diag- The similar genus Australospirifer Caster, 1939 from nostic character of the family is the presence of a capil- the Malvinocaffric Realm (South Africa, southern and east- late micro-ornamentation. However, a family diagnosis ern South America, Antarctica) is characterized by the must harmonize with the morphology of its type genus. presence of a subdelthyrial plate (Boucot et al. 1965, Pl. 7, Due to the new observations, the family Acrospiriferidae Fig. 11, Pl. 8, Figs 7ñ8) which is absent in Acrospirifer. can hardly be maintained in its present version. For comparison with Patriaspirifer see above, under Comparison: Acrospirifer is more or less closely re- ìdiscussionî. lated to several other Lower Devonian hysterolitines with Rostrospirifer Grabau, 1931 and Otospirifer Hou et coarsely ribbed or plicate shells bearing a fimbriate mi- Xian, 1975 from China have more transversely elongat- cro-ornamentation. Some of these were assigned to ed shells and more plications, so that they rather resem- Acrospirifer in earlier times. Within the whole group, ble Euryspirifer.

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The forms bearing an exclusively capillate micro-or- ? 1957 Hysterolites (Acrospirifer) sp. aff. fallax (Giebel). ñ Jentsch namentation from the Lower Devonian (Siegenian ñ ñ Rˆder, p. 124, 127, Pl. 6, Fig. 3. v 1960 Acrospirifer primaevus. ñ Paproth, Tab. 1, Pl. 1, Fig. 8, Pl. 3, Emsian) of West Europe and North Africa which have Figs 6ñ7. been assigned to Acrospirifer up to now do not belong 1960 Hysterolites (Acrospirifer) primaevus. ñ Jentsch, p. 193ñ194, to this genus (see above, in the discussion). They belong Pl. 19, Figs 4ñ5, 7. to the genus Filispirifer comprising the group of ìSpiri- non1961 Acrospirifer primaevus kasachstanica Kaplun, p. 101ñ105, Pl. 17, Figs 5ñ9. ñ [completely different micro-ornamenta- ferî fallax Giebel, 1858 which is probably closely relat- tion]. ed to the capillate genus Mauispirifer Allan, 1947. v 1963 Acrospirifer primaevus. ñ Vandercammen, p. 12ñ19, Pl. 1 Multispirifer Kaplun, 1961 (type-species Spirifer sol- Figs 13ñ20, Pl. 2, Figs 1ñ10, 12ñ13 (non Fig. 11), Text-figs itarius Krantz, 1857) from the Middle Siegenian of the 4ñ9. v 1963 Spirifer primaevus. ñ Martin, Pl. 7, Fig. 4. Rheinisches Schiefergebirge is characterized by a capil- 1965 Acrospirifer primaevus. ñ Pitrat, H 682, Fig. 553. late micro-ornamentation as well; further, it has bifurcat- v 1971 Acrospirifer primaevus. ñ Jahnke, p. 37, Pl. 11, Figs 25añ ing costae. b. ñ [designation and re-figuration of lectotype]. 1973 Spirifer primaevus. ñ Waterlot et al., Pl. 2, Fig. 5. ? 1973 Acrospirifer primaevus. ñ Mittmeyer, p. 89ñ90, Pl. 2, Acrospirifer primaevus (Steininger, 1853) Figs 21ñ31. ñ [1973b]. Pl. I, Figs 1ñ14; Pl. II, Figs 1ñ12; Pl. III, Figs 1ñ7 v 1974 Acrospirifer primaevus. ñ Langsdorf, p. 379ñ380, Fig. 2. ? 1981 Acrospirifer primaevus. ñ Evans, p. 521, Pl. 1, Figs añb. v * 1853 Spirifera primaeva Steininger, p. 72, Pl. 6, Fig. 1. 1982 Acrospirifer primaevus. ñ Carls et al., p. 182ñ183, 185, 189, 1857 Spirifer socialis Krantz, p. 151ñ152, Pl. 8, Figs 3a, c, d (non 190ñ191, Fig. 3. Fig. 3b = Vandercammenina bischofi (Giebel, 1858)). 1982 Acrospirifer primaevus. ñ Fuchs, p. 231, 233ñ234, 252, ? 1864 Spirifera cultrijugata ? F. Roemer. ñ Davidson, p. 35ñ36, Fig. 10. Pl. 8, Figs 1ñ3. 1982 Acrospirifer primaevus. ñ Mittmeyer, p. 259ñ262, chart 1. 1885 Spir. paradoxus Schl. ñ Quenstedt, p. 727ñ728, Pl. 56, 1987 Acrospirifer primaevus. ñ Carls, p. 82ñ84, 99, Fig. 3. Fig. 20. ñ [non von Schlotheim 1813]. non1989 Acrospirifer primaevus. ñ Gourvennec, p. 61ñ67, Text-figs v 1886 Spirifer prohystericus Maurer, p. 19. ñ [semi-adult speci- 32ñ35, Pl. 3, Figs 1ñ13. ñ [= a species of Filispirifer]. mens of A.†primaevus]. ? 1989 Acrospirifer primaevus. ñ Chlup·Ë, p. 373, 378ñ379, 388, 1897 Spirifer primaevus. ñ Frech, p. 139ñ141, 143ñ144, Pl. 23a, Fig. 5: 8ñ9. Fig. 6. 1994 Acrospirifer primaevus. ñ Godefroid et al., Figs 2, 11. 1900 Spirifer primaevus. ñ Scupin, p. 16, 35, 84, 89, 92, 121, 123, v 2001 Acrospirifer primaevus. ñ Jansen, p. 286ñ287, Pl. 33, Figs 128ñ130, 132, Pl. 8, Fig. 9. 1ñ8. 1900 Spirifer subhystericus nov. nom. Scupin, p. 15ñ16, Pl. 8, Figs 9ñ10. ñ [semi-adult specimens of A. primaevus]. Lectotype: designated by Jahnke (1971, p. 37); ventral valve ex- 1904 Spirifer primaevus. ñ Drevermann, p. 246ñ249, Pl. 29, ternal mould figured by Steininger (1853, Pl. 6, Fig. 1); internal Figs 1ñ7. mould belonging to the external mould is also present. Gypsoplasts 1910 Spirifer primaevus. ñ Assmann, p. 140, Pl. 6, Figs 1ñ4. and a latex cast are re-figured herein on Pl. I, Figs 1ñ3. The origi- 1913 Spirifer primaevus. ñ Asselbergs, p. 102. nal material is housed in the Palaeontological Museum of the Hum- 1913 Spirifer primaevus. ñ Kegel, p. 108ñ110, 145, 149, 151, 156, boldt University, Berlin. 162, Pl. 6, Figs 3ñ4. Dimensions: ventral valve external mould: length > 50 mm, width 1923 Spirifer primaevus. ñ Helmbrecht ñ Wedekind, p. 949, 951ñ > 68 mm; number of plications on each flank (referred to the former 953. shell): 11. ñ ventral valve internal mould: length > 42 mm, width ? 1923 Spirifer septalis. ñ Helmbrecht ñ Wedekind, p. 952ñ953. = ca. 65 mm; length of muscle field = ca. 27 mm, width = ca. 1923 Spirifer primaevus. ñ Quiring, p. 91, 94, 98ñ100, 102ñ111. 19.5 mm; there are 8 (+ 1) plications on each flank of the internal 1931 Spirifer primaevus. ñ Dahmer, p. 87, Pl. 7, Fig. 3. mould. The ventral interarea is 10 mm high. 1931 Spirifer (Acrospirifer) primaevus. ñ Maillieux, p. 44ñ47, Type horizon: (? Upper) Siegen Formation, (? Upper) Siegenian. Pl. 2, Figs 1, 1a, 2, 2a. Type locality: Herdorf, Siegerland area, northern Rheinisches 1932 Spirifer primaevus. ñ Dahmer, p. 373. Schiefergebirge, Germany. 1934 Spirifer primaevus. ñ Dahmer: mentioned many times. Stratigraphical range: The species is a classical index fos- v 1934 Spirifer prohystericus Maurer, 1886. ñ Dahmer, p. 71ñ72, sil for the Middle to Upper Siegenian (high Pragian in its original Pl. 8, Fig. 1. sense); ? lowest Emsian (Ulmen Group). 1935 Spirifer primaevus. ñ Dahmer, p. 133ñ138. ñ [1935a]. Distribution: Rheinisches Schiefergebirge, Germany; Ardennes, 1935 Spirifer primaevus. ñ Dahmer, p. 140. ñ [1935b]. Belgium; ? S-England; ? Czech Republic. ñ Localities in Germa- v 1936 Spirifer primaevus. ñ Rose, p. 52, 57. ny, formations of Middle to Late Siegenian age: Siegerland area, 1936 Spirifer primaevus. ñ Dahmer, p. 25ñ27, Pl. 6, Figs 1ñ2, Siegen Formation: for localities see Paproth (1960), Quiring (1923); Text-fig. 2. ñ [1936a]. Westerwald area, Seifen Formation: see Dahmer (1934); Middle 1936 Spirifer primaevus. ñ Dahmer, p. 641, 645. ñ [1936b]. Rhine area near Bonn, Siegen Formation: see Dahmer (1931, 1937 Spirifer primaevus. ñ Kutscher: mentioned many times. 1936b); southern Rheinisches Schiefergebirge, Taunusquarzit For- 1937 Spirifer primaevus. ñ Dahmer, p. 446ñ450, 452ñ453, 455ñ mation: see Kutscher (1937, 1952), Jentsch ñ Rˆder (1957); west- 456, 458. ern Rheinisches Schiefergebirge, Eifel Hills: see Dahmer (1937, v 1940 Spirifer primaevus. ñ Simpson, p. 59, Tab. 4, Pl. 6, Fig. 5. 1940), Simpson (1940), Fuchs (1982). ñ Uncertain: central Rhein- v 1940 Spirifer primaevus. ñ Dahmer, p. 81. isches Schiefergebirge, Middle Rhine area, Ulmen Group, lower 1940 Spirifer primaevus. ñ Kutscher, p. 107, 110ñ115, Pl. 1, Lower Emsian: see Mittmeyer (1973b). ñ Localities in Belgium, Fig. 1. Ardennes, formations of Siegenian age: see Asselbergs (1913), 1950 Spirifer primaevus. ñ Solle: mentioned many times. Maillieux (1931, 1936), Vandercammen (1963), Godefroid et al. 1952 Spirifer primaevus. ñ Kutscher, p. 87, 89. (1994). ñ Uncertain: southern England, Siegenian: see Davidson 1957 Hysterolites (Acrospirifer) primaevus. ñ Jentsch ñ Rˆder, (1864), Evans (1981). ñ Uncertain: Czech Republic, Hrub˝ JesenÌk p. 124. Mountains, Siegenian: see Chlup·Ë (1989). ? 1957 Hysterolites (Acrospirifer) fallax (Giebel). ñ Jentsch ñ Rˆ- Studied materials: The investigated specimens are stored in der, p. 124, 127, Pl. 6, Fig. 2. the Senckenberg-Museum, Frankfurt am Main/Germany (collection

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numbers: SMF...). The specimens are preserved as internal and ex- cardinal extremities are often present. Dorsal valve with ternal moulds. Latex casts have been made in order to be better high fold, ventral valve with corresponding deep sulcus. able to describe the internal morphology of the valves and to make visible the external micro-ornamentation. The best-preserved spec- Sulcus angular in cross section, moderately wide, with imens exhibiting details of the micro-ornamentation come from the faint median costa. Fold moderately wide, angular in localities ìSeifenî (Westerwald area) and ìEtzbachî (Siegerland cross section, without plications or costae. Plications of area). ñ Following type specimens have been investigated: lecto- the flanks very strong, non-bifurcating, angular in cross type, ventral valve internal and external moulds (gypsoplasts); SMF 19236añb. ñ List of investigated materials from different localities section. The number of plications generally ranges from in the Rheinisches Schiefergebirge; all strata are of Middle to Late 8 to 12 on each flank. Plications bounding the sulcus are Siegenian age [abbreviations: DVI = dorsal valve internal mould(s), mostly not weakened and not situated at a lower level VVI = ventral valve internal mould(s), DVE = dorsal valve exter- with respect to the adjacent second plications. Only in nal mould(s), VVE = ventral valve external mould(s), DVI/VVI = internal mould of both valves in conjoined condition, TM25 = to- rare cases, they are weaker than the second plications and pographic mapsheet 1:25000]: included in the sulcus. Etzbach/Sieg, Siegerland area (TM25 No. 5212 Wissen): 17 VVI, The micro-ornamentation consists of short segments 14 DVKI, 1 DVI/VVI, 4 VVE; SMF 59870, 59877ñ59879, 59887, of fine pseudoradial striae (ìcapillaeî) terminating as a 65089ñ65091, 65093, 65095, 65097ñ65098, 65101, 65318, 65368, 65878. ñ Augustenthal near Neuwied (TM25 Neuwied/Rhein, fringe of micro-spines situated at the anterior margin of No. 5510); Augustenthal Formation, Middle Siegenian: 1 DVI, each growth lamella. Concentric growth lamellae more 2 VVI, 1 VVE; SMF XVII 989a. ñ Seifen, Westerwald area (TM25 or less strongly developed and imbricating, typically Altenkirchen, No. 5311); Seifen Formation, Middle Siegenian: showing a somewhat irregular course; distances between 7 VVI, 5 DVI, 5 VVE, 4 DVE; SMF 59873ñ59874, 59882ñ59883, 59916, 65053, 65088, 65092, 65094, 65096, 65099ñ65100, 65868, the succeeding lamellae are different; the lamellae are 65872, 65879ñ65880, 65882ñ65886. ñ Ascheid, Westerwald area crowded in the periphery of adult shells. ìCapillaeî in (TM25 Altenkirchen, No. 5311); Seifen Formation, Middle Siege- A.†primaevus are generally not developed as continuous nian: 1 DVE; SMF 59876. ñ Nieder‰hren, Westerwald area, quar- ry near the road from Puderbach to Seifen (TM25 Altenkirchen, (pseudo-)radial ridges which are typical of the real capil- No. 5311); Seifen Formation, Middle Siegenian: 11 DVI, 13 VVI, late condition. In well-preserved specimens, there are no 2 VVE; SMF 65891. ñ M¸hlmerich quarry near Eichen/Westerwald capillae in the proper meaning; these are frequently in- area (TM25 Altenkirchen, No. 5311); Seifen Formation, Middle terrupted and rather occur as subordinate spine bases. The Siegenian: 5 DVI, 10 VVI, 1 DVI/VVI, 1 DVE, 2 VVE; SMF XV 1676 d, XVII 398a, XVII 398x, XVII 932d, 65890. ñ Weiersbach micro-spines are the dominant sculpture element. There- mill (Lieser valley), road cut behind the mill, Eifel Hills (TM25 fore, the micro-ornamentation as a whole is clearly of the Daun, No. 5806); Saxler Formation, Upper Siegenian: 1 DVI, 1 VVI fimbriate type. The spines are rod-like and circular in (original specimens of Simpson 1940); SMF XVII 398m, XVII cross-section. They are about 0.05 mm in diameter. There 398p. ñ Saxler, road to Ellscheid, Eifel Hills (TM25 Gillenfeld, No. 5807); Saxler Formation, Upper Siegenian: 3 DVI (original are 8 to 12 spines in 1 mm along a concentric growth specimens of Simpson 1940); SMF 398f. ñ Ollenbachtal, Auder- lamella. The spines are regularly arranged in concentric ath mill, small quarry, Eifel Hills (TM25 Gillenfeld, No. 5807); rows and subequal in size. Saxler Formation, Upper Siegenian: 1 DVI (original specimen of Depending on the degree of abrasion of the shell, the Simpson 1940); SMF XVII 398r. ñ Berenbach, Eifel Hills (TM25 Kelberg, No. 5707); Saxler Formation, Upper Siegenian: 1 DVI, micro-ornamentation exhibits different stages of preser- 1 VVI (original specimens of Simpson 1940); SMF 398g. ñ Road vation. If the shell is not well enough preserved (what is cut SW Schˆnbach, Eifel Hills (TM25 Kelberg, No. 5707); Saxler frequently the case), the spines are broken off and the Formation, Upper Siegenian: 1 VVI (original specimen of Simp- micro-ornamentation may show a ìpseudo-capillateî con- son 1940); SMF XVII 398h. ñ Road from B¸rresheim to Kirchesch (TM25 Virneburg, No. 5608); Middle Siegen Formation, Middle dition. Siegenian: 1 DVI, 1VVI, 1 DVI/VVI, 1 DVE (original specimens Ventral interarea high (reaching > 10 mm), apsacline, of Dahmer 1940); SMF 398w. ñ Quarry W Kˆpfchen near Wald- concave in longitudinal section, surface largely smooth, Erbach, Hunsr¸ck Hills (TM25 Stromberg, No. 6012); Upper Tau- nusquarzit Formation: 1 VVI, 1 VVE; SMF 65881. ñ Homburg, with very fine growth lines running parallel to the hinge Kirbach mill, Taunus Hills (TM25 Bad Homburg v. d. Hˆhe, line. Delthyrium large, open, triangular, bordered by a No. 5717); Taunusquarzit Formation: 1 VVE; SMF XVII 3110. ñ pair of thin deltidial lamellae. Dorsal interarea low, ap- 100 m W Rheinstein castle (TM25 Bingen, No. 6013); Tau- proximately orthocline. Notothyrium open. nusquarzit Formation: 1 VVI, 1 VVE; SMF 65887. ñ Leingipfel near R¸desheim/Rhine, Taunus Hills (TM25 Bingen, Nr. 6013); Up- Shells of both valves very thick, especially in the um- per Taunusquarzit Formation: 1 DVI, 31 VVI, 2 VVE; SMF 65870ñ bonal regions, probably to help the living animal in main- 65877. ñ Hartberg, W Bingen (TM25 Bingen, Nr. 6013); Upper taining a beak-down orientation in its life position, and Taunusquarzit Formation: 4 DVI, 7 VVI, 1 DVE; SMF 65888. ñ assisting the pedicle. Allerbach, W Bingerbr¸ck (TM25 Bingen, Nr. 6013); Taunusquarzit Formation: 4 DVI, 16 VVI, 1 DVE; SMF 65889. ñ Waldesch near Ventral valve interior. ñ Apical cavity subdivided by Mayen, Eifel Hills, Siegen Formation: 1 DVI; SMF 65869. dental plates into a central cavity and two lateral cavi- ties. In juvenile and semi-adult ontogenetic stages (ìpro- Diagnosis: as for the genus. hystericusî-stage), short to moderately long free dental Description of the species (based on mate- plates are present which leave, on the ventral internal rials cited above): Exterior. ñ Shells large, strongly bi- mould, corresponding incisions lateral to the muscle convex, semicircular to somewhat transversely semiellip- field. Due to extensive deposition of secondary materi- tical in outline, equithyrid to megathyrid, with sulcus and al, the free parts of the dental plates almost disappear in fold flanked by plicate lateral areas. The shells reach large specimens. The dental plates are subdivided into some 70 mm width and 50 mm length. Short mucronate dental flange and ventral adminiculum. Dental flanges

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support prominent hinge teeth. On the internal mould, the above the surrounding floor of the internal mould. Free incisions left by the dental plates are situated lateral to crural bases are little pronounced. Free crural plates the sulcus, in the backward prolongation of the second (= dorsal adminicula) and outer hinge plates are absent. to third plications of the flanks. The dental plates are fol- Lateral to the dorsal adductor field, the surface shows lowed by very faint muscle bounding ridges enclosing the a peculiar pattern of irregular impressions probably left muscle field. Deltidial furrows present, situated just be- by the gonads; only visible in well-preserved speci- low the delthyrial margins. mens. Depending on the extent of umbonal shell thickenings, On the dorsal valve internal mould, generally 6 to 7 the lateral apical cavities are more or less clearly pro- strong plications have been counted on each flank, rare- nounced. They can leave sharp or rounded projections on ly 8 or 9. The first two or three pairs of plications begin the internal mould. There is a small median process bi- within the adductor field, the others lateral to it. The fold secting the ventral muscle field in its posterior part. On of the internal mould is subangular in cross section. the internal mould, this process leaves a clear median in- cision. The process grades anteriorly into a thin myo- Summary phragm which reaches about the midlength of the mus- cle field. The type species of Acrospirifer, A. primaevus (Steininger, The ventral muscle field reaches about the half length 1853), has been redescribed. Well-preserved specimens of the valve; it is suboval to rhomboid in outline, longer from the type region of the species (Rheinisches Schief- than wide, deeply impressed; diductor and adductor scars ergebirge, Germany) exhibit a fimbriate micro-ornamen- are arranged in pairs. Adductor scars long and narrow, tation with rows of micro-spines along each concentric situated in the sulcus area. Diductor scars lie lateral to growth lamella. Moreover, a strongly developed notothy- the adductor scars and bear fine striations which bifur- rial platform in the dorsal valve is present in most speci- cate. The muscle field leaves a kind of cone on the in- mens. Because these observations contradict the last pub- ternal mould (in German: ìMuskel-Zapfenî). One to lished diagnosis of the genus based on Armorican material three pairs of plications run through this cone so that it (Gourvennec 1989), a new diagnosis is erected. In North gets an angular appearance. The muscle field is delimit- Gondwanan regions, similar but purely capillate forms ed anteriorly by a change in curvature and by the mus- occur which have hitherto been assigned to Acrospirifer. cle bounding ridges. These forms, belonging to the group around ìSpiriferî fal- The surface of the internal mould lateral to the mus- lax Giebel, 1858, are now assigned to the genus Filispiri- cle field is flattened and forms a kind of platform. In fer Jansen, 2001. Apart from the different micro-ornamen- adult specimens, this area bears fine tubercles (small pits tation, they are further discriminated from Acrospirifer by on the interior shell surface) which may have been left the absence of a strongly developed notothyrial platform by the gonads. In this area, the plications are still weak and by the presence of sulcus bounding plications which or lacking. are commonly weakened and included in the sulcus. The In the peripheral regions of the internal mould, the taxonomic status of the rare capillate species ìSpiriferî plications are almost as strong as on the shell surface. beaujeani BÈclard, 1887 from the Siegenian of Belgium The number of plications normally reaches 7 to 8 on each remains uncertain; perhaps it belongs to Filispirifer as flank, in rare cases 9. The sulcus of the internal mould well. is rounded to subangular in cross section. The North American genus Patriaspirifer Johnson, Dorsal valve interior. ñ Apical cavity delimited lateral- 1995, which has mainly been discriminated from ly by thick inner socket ridges. Notothyrial platform Acrospirifer by the presence of a fimbriate micro-orna- present, generally strong. In few specimens, the platform mentation, is to be re-evaluated, because this difference is only moderately or even poorly developed. Ctenopho- is not present. It appears, that there are minor differenc- ridium (= dorsal diductor field) clearly developed, consist- es concerning the cardinalia so that it seems to be justi- ing of many and very thin lamellae, elevated on the no- fied to maintain this genus. tothyrial platform. Dental sockets begin thin apically and According to the present knowledge, Acrospirifer is re- become suddenly voluminous distally. They are support- stricted to its type species probably only occurring in the ed by thick callosities dorsally. Dorsal adductor field deep- Ardenno-Rhenish Mountains (uncertain occurrences in ly impressed in most specimens, adductor scars arranged southern England and in the Czech Republic). It is re-com- in pairs, irregularly striated. Adductor field commonly bi- mended to re-evaluate all determinations of Acrospirifer sected by a strong median process in its posterior part, in the Mauro-Ibero-Armorican region. Stratigraphical and process grading into a fine and very long myophragm. The palaeobiogeographical conclusions drawn on the base of median process is variable in size; in few specimens it is the supposed occurrences should be reconsidered as well. almost lacking, and there is only a faint myophragm in- The family Acrospiriferidae in the sense of Carter stead. The internal mould of the dorsal adductor field over- et al. (1994) can hardly be maintained any further be- hangs the hinge line posteriorly; it is more or less raised cause it has been defined as capillate.

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Acknowledgements. I thank Dr. G. Plodowski, For- Jahrbuch f¸r Geologie und Pal‰ontologie, Abhandlungen, 177(3): schungsinstitut Senckenberg (Frankfurt on Main) for dis- 367ñ392. cussions. Thanks also to U. Schwieger, Forschungsinsti- Cooper, G. A. (1949): Phylum Brachiopoda. In: Shimer ñ Shrock (Eds) Index Fossils of North America: New York, John Wiley & Sons; tut Senckenberg, for preparing the photographs. I am London, Chapman & Hall: 277ñ365. greatly indebted to E. Grebel, Dierdorf, who collected a Dahmer, G. (1931): Fauna der belgischen ìQuartzophyllades de Longlierî part of the well-preserved material. in Siegener Rauhflaserschichten auf Blatt Neuwied. ñ Jahrbuch der Thanks are also due to Prof. Dr. P. Carls (University preuflischen geologischen Landesanstalt f¸r 1931, 52: 86ñ111. of Braunschweig) and Dr. H. Jahnke (University of Gˆt- ñ (1932): Beziehungen zwischen den Faunen von Neuwied und Juseret (Siegen-Stufe). ñ Senckenbergiana, 14(4/5): 372ñ385. tingen) who gave me the opportunity to study materials ñ (1934): Die Fauna der Seifener Schichten (Siegenstufe). ñ Abhand- collected by them in the Celtiberian Chains and the lungen der preuflischen geologischen Landesanstalt, Neue Folge, Kellerwald Mountains. 147: 1ñ91. This work is a contribution to UNESCO-IGCP Project ñ (1935a): Die Fauna der Siegener Schichten in der Umgebung des 421 ìNorth Gondwanan mid-Palaeozoic bioevent/bioge- Laacher Sees. ñ Jahrbuch der preuflischen geologischen Landesanstalt f¸r 1934, 55: 122ñ141. ography patterns in relation to crustal dynamicsî. ñ (1935b): Revision der Fauna von Menzenberg (Siegen-Stufe). ñ Submitted December 13, 2000 Decheniana, Verhandlungen des Naturhistorischen Vereins der Rheinlande und Westfalens, 91: 135ñ150. ñ (1936a): Die Fauna der Obersten Siegener Schichten von der References Unkelm¸hle bei Eitorf a. d. Sieg. ñ Abhandlungen der preuflischen geologischen Landesanstalt, Neue Folge, 168: 3ñ36. Allan, R. S. (1935): The Fauna of the Reefton Beds, (Devonian) New ñ (1936b): Die Fauna der Siegener Schichten von Unkel (Bl. Kˆnigs- Zealand. ñ Palaeontological Bulletin, 14: 1ñ72. winter). ñ Jahrbuch der preuflischen geologischen Landesanstalt f¸r Amsden, T. W. ñ Ventress, W. P. S. (1963): Early Devonian brachiopods of 1935, 56: 633ñ671. Oklahoma. ñ Bulletin Oklahoma geological Survey, 94: 1ñ238. ñ (1937): Die Fauna der Siegener Schichten im Ahrgebiet (Nordost- Asselbergs, …. (1913): Le DÈvonien infÈrieur du Bassin de líEifel et de Eifel). ñ Jahrbuch der preuflischen geologischen Landesanstalt f¸r líAnticlinal de Givonne. ñ MÈmoires de líInstitut gÈologique de 1936, 57: 435ñ464. líUniversitÈ de Louvain, 1(1): 3ñ174. ñ (1940): Die Fauna der Siegener Schichten (Unter-Devon) zwischen Assmann, P. (1910): Die Fauna der Erbslochgrauwacke bei Densberg im B¸rresheim und Kirchesch in der S¸dost-Eifel. ñ Senckenbergiana, Kellerwald. ñ Jahrbuch der preuflischen geologischen Landesanstalt 22(1/2): 77ñ102. f¸r 1910, 31: 136ñ172. Davidson, T. (1864): A monograph of British Devonian Brachiopoda, Benedetto, J. L. (1984): Les brachiopodes dÈvoniens de la Sierra de Perija 6(1) ñ London, Palaeontographical Society, 56 pp. (Venezuela). ñ Biostratigraphie du PalÈozoïque, 1: 1ñ191. Drevermann, F. (1904): Die Fauna der Siegener Schichten von Seifen Bizzarro, M. ñ LespÈrance, P. J. (1999): Systematics of some Lower and unweit Dierdorf (Westerwald). ñ Palaeontographica, 50: 229ñ287. Middle Devonian spiriferid brachiopods from GaspÈ with a revision Drot, J. (1964): Rhynchonelloidea et Spiriferoidea siluro-dÈvoniens du of the Superfamily Delthyridoidea. ñ Journal of Paleontology, 73(6): Maroc prÈ-saharien. ñ Notes et MÈmoires du Service gÈologique du 1056ñ1077. Maroc, 178: 1ñ288. Boucot, A. J. (1973): Early Paleozoic Brachiopods of the Moose River Evans, K. M. (1985): The brachiopod fauna of the Meadfood group (Lower Synclinorium, Maine. ñ Geological Survey Professional Paper, 784: Devonian) of the Torbay area, South Devon. ñ Geological Journal, 1ñ81. 20: 81ñ90. Boucot, A. J. ñ Johnson, J. G. ñ Doumani, G. A. (1965): Articulate Frech, F. (1897): Lethaea geognostica, 1, Lethaea palaeozoica, 2(1) ñ Brachiopoda. ñ Antarctic Res. Ser., 6. Geology and Paleontology of Stuttgart, E. Schweizerbartísche Verlagshandlung, 256 pp. the Antarctic: 241ñ281. Fuchs, G. (1982): Upper Siegenian and Lower Emsian in the Eifel Hills. Carls, P. (1987): Ein Vorschlag zur biostratigraphischen Redefinition der ñ Courier Forschungsinstitut Senckenberg, 55: 229ñ256. Grenze Gedinnium/Siegenium und benachbarter Unter-Stufen. ñ (1989): Die unterdevonische Schichtenfolge bei Neuerburg in der 1.†Teil: Stratigraphische Argumente und Korrelation. ñ Courier Westeifel. ñ Mainzer geowissenschaftliche Mitteilungen, 18: 103ñ Forschungsinstitut Senckenberg, 92: 77ñ121. 124. ñ (1999): El DevÛnico de Celtiberia y sus fÛsiles. ñ In: G·mez Vintaned, GarcÌa-Alcalde, J. L. ñ Arbizu, M. ñ GarcÌa-LÛpez, S. ñ Leyva, F. ñ J. A. ñ Liñ·n, E. (Eds) VI Jornadas Aragonesas de Paleontologia: Montesinos, R. ñ Soto, F. ñ TruyÛls-Massoni, M. (1990): Devonian Zaragoza, InstituciÛn ìFernando el CatÛlicoî, Excma. 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(1999): Early Devonian (late Emsian) Brachio- SociÈtÈ GÈologique du Nord, 5(2): 108ñ111. pods from Zhongping, Xianzhou, central Guangxi, China. ñ Sencken- HavlÌËek, V. (1959): Spiriferidae v ËeskÈm siluru a devonu (Brachiopoda). bergiana lethaea, 79(1): 223ñ265. ñ Rozpravy ⁄st¯ednÌho ⁄stavu geologickÈho, 25: 1ñ275. Chlup·Ë, I. (1989): Fossil communities in the metamorphic Lower De- Helmbrecht, W. ñ Wedekind, R. (1923): Versuch einer biostratigraphischen vonian of the Hrub˝ JesenÌk Mts., Czechoslovakia. ñ Neues Gliederung der Siegener Schichten auf Grund von Rensselaerien und

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Spiriferen. ñ Gl¸ckauf, Berg- und H¸ttenm‰nnische Zeitschrift, Homburg vor der Hˆhe (Bad Homburg vor der Hˆhe: Verlag des 41: 949ñ953. Taunusboten), 28: 1ñ110. Jahnke, H. (1971): Fauna und Alter der Erbslochgrauwacke (Brachiopoden Maurer, F. (1886): Die Fauna des rechtsrheinischen Unterdevon aus meiner und Trilobiten, Unter-Devon, Rheinisches Schiefergebirge und Harz). Sammlung zum Nachweis der Gliederung. ñ Neues Jahrbuch f¸r ñ Gˆttinger Arbeiten zur Geologie und Pal‰ontologie, 9: 1ñ105. Mineralogie, Geologie und Palaeontologie, 1882(1): 3ñ55. Jahnke, H. ñ Henn, A. ñ Schweineberg, J. (1983): Silur und Devon im Merriam, C. W. (1940): Devonian stratigraphy and paleontology of the Arauz-Gebiet (Prov. Palencia, N-Spanien). ñ Newsletters on Strati- Roberts Mountains region. ñ Geological Society of America Special graphy, 13(1): 40ñ66. Papers, 25: 1ñ114. Jansen, U. (2000). The Early Devonian genus Acrospirifer. A taxonomic Mittmeyer, H.-G. (1972): Delthyrididae und Spinocyrtiidae (Brachiopoda) odyssey. ñ The Millenium Brachiopod Congress, Abstracts: London. des tiefen Ober-Ems im Mosel-Gebiet (Ems-Quarzit, Rheinisches ñ (2001): Morphologie, Taxonomie und Phylogenie unter-devonischer Schiefergebirge). ñ Mainzer geowissenschaftliche Mitteilungen, Brachiopoden aus der Dra-Ebene (Marokko, Pr‰-Sahara) und dem 1: 82ñ121. Rheinischen Schiefergebirge (Deutschland). ñ Abhandlungen der ñ (1973a): Die Hunsr¸ckschiefer-Fauna des Wisper-Gebietes im senckenbergischen naturforschenden Gesellschaft, 554: 1ñ389. Taunus. Ulmen-Gruppe, tiefes Unterems, Rheinisches Schiefergebirge. Jentsch, S. (1960): Die Moselmulde und ihre s¸dˆstlichsten Randstrukturen ñ Notizblatt des hessischen Landesamtes f¸r Bodenforschung, zwischen Lahn und Westerwald. ñ Notizblatt des hessischen Landes- 101: 16ñ45. amtes f¸r Bodenforschung, 88: 190ñ215. ñ (1973b): Grenze Siegen/Unterems bei Bornhofen (Unter-Devon, Jentsch, S. ñ Rˆder, D. (1957): Zur Geologie des Taunusquarzits bei Bad Mittelrhein). ñ Mainzer geowissenschaftliche Mitteilungen, 2: 71ñ103. Homburg. ñ Notizblatt des hessischen Landesamtes f¸r Bodenfor- ñ (1982): Rhenish Lower Devonian biostratigraphy. ñ Courier For- schung, 85: 114ñ128. schungsinstitut Senckenberg, 55: 257ñ269. Johnson, J. G. (1970): Great Basin Lower Devonian Brachiopoda. ñ Geo- Paproth, E. (1960): ‹ber die Fauna der Mittleren Siegener Schichten des logical Society of America Memoirs, 121: 1ñ421. Siegerlandes. ñ Abhandlungen des hessischen Landesamtes f¸r ñ (1995): Taxonomic note: Patriaspirifer, a new genus of Lower De- Bodenforschung, 29: 321ñ339. vonian spiriferid brachiopods. ñ Journal of Paleontology, 69(1): 198. Pitrat, C. W. (1965): Spiriferidina. In: Moore, R. C. (Ed.) Treatise on Kaplun, L. I. (1961): Brakhiopody niznego devona severnogo pribalkha- Invertebrate Paleontology, Part H, Brachiopoda, 2: Lawrence, The shya. In: Materialy po geologii i poleznym iskopaemym Kazakhstana. University of Kansas Press: H667ñH728. Stratigrafiya i paleontologiya: Moskwa: 64ñ114. Plusquellec, Y. ñ Jahnke, H. (1999): Les tabulÈs de líErbslochgrauwacke Kegel, W. (1913): Der Taunusquarzit von Katzenelnbogen. ñ Abhandlungen (Emsien infÈrieur du Kellerwald) et le problème des affinitÈs palÈo- der kˆniglich preuflischen geologischen Landesanstalt, Neue Folge, gÈographiques de líallochtone ìGieflen-Harzî. ñ Abhandlungen der 76: 1ñ162. Geologischen Bundesanstalt Wien, 54: 435ñ451. Krantz, A. (1857): ‹ber ein neues bei Menzenberg aufgeschlossenes Quenstedt, F. A. (1885): Handbuch der Petrefaktenunde (3rd Ed.): Petrefakten-Lager in den devonischen Schichten. ñ Verhandlungen T¸bingen, Verlag der H. Lauppíschen Buchhandlung, 1239 pp. des naturwissenschaftlichen Vereins von Rheinland und Westfalen, Quiring, H. (1923): Beitr‰ge zur Geologie des Siegerlandes. III. ‹ber 14: 143ñ165. Leitformen in den Siegener Schichten der Umgebung von Siegen. ñ Kutscher, F. (1937): Taunusquarzit, Throner Quarzite und Hunsr¸ckschiefer Jahrbuch der preuflischen geologischen Landesanstalt f¸r 1922, des Hunsr¸cks und ihre stratigraphische Stellung. ñ Jahrbuch der 43: 90ñ112. preuflischen geologischen Landesanstalt f¸r 1936, 57(1): 186ñ237. Renaud, A. (1942): Le DÈvonien du Synclinorium mÈdian Brest-Laval. ñ ñ (1940): Fossilvorkommen im Taunusquarzitzuge Weissfels-Hujets, MÈmoires de la SociÈtÈ GÈologique et MinÈralogique de Bretagne, S‰gem¸hle-Wehlenstein des Bl. Birkenfeld-West (Hunsr¸ck). ñ 7: 1ñ439. Decheniana, 99A: 105ñ118. Robardet, M. ñ Paris, F. ñ Racheboeuf, P. R. (1990): Palaeogeographic ñ (1952): Fossilfunde im Taunusquarzit des westlichen Soonwaldes evolution of southwestern Europe during Early Palaeozoic times. ñ (Hunsr¸ck). ñ Notizblatt des hessischen Landesamtes f¸r Bodenfor- In: McKerrow, W. S. ñ Scotese, C. R. (Eds) Palaeozoic Palaeogeo- schung, 3(6): 87ñ90. graphy and Biogeography. ñ Mem. Geol. Soc., 12: 411ñ419. Langsdorf, W. (1974): Geologische Untersuchungen im Unter-Devon der Rose, O. (1936): Versteinerungen im Taunusquarzit des Rheintaunus. ñ Nordflanke der Moselmulde zwischen Bad Bertrich und Kobern/ Jahrbuch des Nassauischen Vereins f¸r Naturkunde, 83: 49ñ58. /Mosel (S¸dost-Eifel, Rheinisches Schiefergebirge). ñ Neues Jahrbuch Schlotheim, E. F. von (1813): Beitr‰ge zur Naturgeschichte der Versteine- f¸r Geologie und Pal‰ontologie, Abhandlungen, 144(3): 373ñ401. rungen in geognostischer Hinsicht. In: Leonhard, Taschenbuch f¸r Laverdière, J. W. (1930): Contribution à líÈtude des terrains palÈozoïques die gesammte Mineralogie, 7(1): 3ñ134. dans les PyrÈnÈes Occidentales. ñ MÈmoires de la SociÈtÈ gÈologique Scupin, H. (1900): Die Spiriferen Deutschlands. ñ Palaeontologische du Nord, 10(2): 1ñ131. Abhandlungen, Neue Folge, 4(3): 207ñ344. Le MaÓtre, D. (1952a): Contribution à líÈtude des faunes palÈozoïques de Simpson, S. (1940): Das Devon der S¸dost-Eifel zwischen Nette und Alf. LíAdrar mauritanien. ñ Bulletin de la Direction des Mines, Gouver- ñ Abhandlungen der senckenbergischen naturforschenden Gesellschaft, nement gÈnÈral de líAfrique Occidentale franÁaise, 15(2): 299ñ383. 447: 1ñ81. Le MaÓtre, D. (1952b): La faune du DÈvonien infÈrieur et moyen de la Solle, G. (1950): Obere Siegener Schichten, Hunsr¸ckschiefer, tiefstes Saoura et des Abords de líErg el Djemel (Sud-Oranais). ñ MatÈriaux Unterkoblenz und ihre Eingliederung ins Rheinische Unterdevon. ñ pour la carte gÈologique de lëAlgÈrie, 1re†sÈr. palÈontologie, 12: 1ñ Geologisches Jahrbuch, 65: 299ñ380. 170. ñ (1953): Die Spiriferen der Gruppe arduennensis-intermedius im Mailleux, E. (1931): La faune des Grès et Schistes de Solières (SiegÈnien rheinischen Devon. ñ Abhandlungen des hessischen Landesamtes moyen). ñ MÈmoirs du MusÈe royal dëHistoire naturelle de Belgique, f¸r Bodenforschung, 5: 1ñ156. 51: 1ñ90. Steininger, J. (1853): Geognostische Beschreibung der Eifel: Trier, ñ (1936): La faune et lí‚ge des quartzophyllades siegÈniennes de Lintzísche Buchhandlung, 144 pp. Longlier. ñ MÈmoirs du MusÈe royal dëHistoire naturelle de Belgique, Vandercammen, A. (1963): Spiriferidae du DÈvonien de la Belgique. ñ 73: 1ñ140. Institut royal des Sciences naturelles de Belgique, MÈmoires, 150: ñ (1941): Les brachiopodes de líEmsien de lëArdenne. ñ MÈmoirs du 1ñ170. MusÈe royal dëHistoire naturelle de Belgique, 96: 3ñ73. Waterlot, G. ñ Beugnies, A. ñ Bintz, J. (1973): Guides gÈologiques Martin, G. P. R. (1963): Kleine Erdgeschichte der Taunuslandschaft um rÈgionaux. Ardenne, Luxembourg: Paris, Masson & Cie, 206 pp. Bad Homburg vor der Hˆhe und Oberursel. Schichten, Gesteine, Wedekind, R. (1926): Die devonische Formation. In: Salomon, Grundz¸ge Mineralquellen und ein Blick auf den ehemaligen Bergbau. ñ der Geologie, 2, Erdgeschichte: Stuttgart, E. Schweizerbartísche Mitteilungen des Vereins f¸r Geschichte und Landeskunde zu Bad Verlagsbuchhandlung: 194ñ226.

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O rodu Acrospirifer Helmbrecht et Wedekind, 1923 (Brachiopoda, spodnÌ devon)

»etnÈ devonskÈ druhy spiriferidnÌch brachiopod˘ se silnÏ plik·tnÌmi miskami, kterÈ byly rozö̯eny tÈmÏr po celÈm svÏtÏ byly p¯i¯azov·ny k†rodu Acrospirifer Helmbrecht et Wedekind, 1923. V†pr˘bÏhu p¯ipravovanÈ revize rodu byl materi·l typovÈho druhu A. primaevus (Steininger, 1853) z†typickÈ oblasti (R˝nskÈ b¯idliËnÈ poho¯Ì) znovu revidov·n. Na dob¯e zachoval˝ch jedincÌch je z¯eteln· fimbri·tnÌ mikroornamentace, s†mal˝mi trny podÈl okraj˘ koncentrick˝ch r˘stov˝ch lamel. Toto zjiötÏnÌ je v†rozporu s†diagnÛzou rodu publikovanou Gourvennecem (1989) a diagnÛzou Ëeledi Acrospiriferidae Termier et Termier, 1949, publikovanou Carterem et al. (1994); v†obou diagnÛz·ch je uveden jako hlavnÌ znak kapil·tnÌ mikro- ornamentace bez drobn˝ch trn˘ na lamel·ch. Na z·kladÏ nov˝ch zjiötÏnÌ je revidov·no urËenÌ rodu Acrospirifer a je diskutov·no taxonomickÈ postavenÌ druh˘ doposud tomuto rodu ¯azen˝ch. Na z·kladÏ souËasn˝ch znalostÌ je rod Acrospirifer ve skuteËnosti omezen pouze na typov˝ druh, kter˝ se vyskytuje v†Arden·ch a Por˝nÌ, a s†pochybnostmi i v†jiûnÌ Anglii a »eskÈ republice.Ve spodnÌm devonu z·padnÌ Evropy a severnÌ Afriky jsou hojnÈ v˝luËnÏ typy s†kapil·tnÌ mikroornamentacÌ, kterÈ byly dosud urËov·ny jako rod Acrospirifer; rovnÏû diagnÛza uvedenÈ Gourvennecem je zaloûena na tÏchto taxonech. Ty vöak nen·leûÌ k†rodu Acrospirifer, ale k†Filispirifer Jansen, 2001 spadajÌcÌmu do okruhu druhu ìSpiriferî fallax Giebel, 1858. Tato skupina druh˘ se rovnÏû vyskytuje ve spodnoemsk˝ch jednotk·ch Erbsloch-Grauwacke a v†Hercynsk˝ch v·pencÌch v†Kellervaldu a pohoûÌ Harz v†NÏmecku. V˝skyty rodu Acrospirifer Ëi dokonce druhu A. primaevus v†z·padnÌ EvropÏ a severnÌ Africe je nutno p¯ehodnotit a rovnÏû tak i stratigrafickÈ z·vÏry vych·zejÌcÌ z tÏchto ˙dajn˝ch v˝skyt˘. RovnÏû je z¯ejmÈ, ûe koncept Ëeledi Acrospiriferidae je tÏûko udrûiteln˝ na z·kladÏ jejÌ souËasnÈ definice.

Explanation of plates

Plate I 1ñ3 ñ Acrospirifer primaevus (Steininger, 1853). Lectotype, ventral valve internal and external moulds, latex cast of internal mould, specimen SMF 19236añb. Locality: Herdorf, Siegerland area, Rheinisches Schiefergebirge. (?†Upper) Siegen Formation, (?†Upper Siegenian): 1 ñ ventral valve internal mould, gypsoplast of the original specimen, x1. 2 ñ latex cast of ventral valve internal mould, x1. 3 ñ ventral valve external mould, gypsoplast, x1. 4 ñ Ventral valve internal mould, juvenile specimen SMF 65890. Locality: Seifen, Westerwald area, Rheinisches Schiefergebirge. Seifen For- mation, Middle Siegenian; x1. 5 ñ Ventral valve internal mould, specimen SMF XV1676d. Locality: M¸hlmerich near Eichen, Westerwald area. Seifen Formation, Middle Siegenian; x1. 6 ñ Ventral valve internal mould, specimen SMF 65876. Locality: Leingipfel, Taunus Hills, southern Rheinisches Schiefergebirge. Upper Tau- nusquarzit Formation, Middle or Upper Siegenian; x1. 7 ñ Ventral valve internal mould, specimen SMF XVII 398m. Locality: Weiersbach mill, Eifel Hills. Saxler Formation, Upper Siegenian; x1. 8 ñ Ventral valve internal mould, specimen SMF 65096a. Locality: Seifen, Westerwald area. Seifen Formation, Middle Siegenian; x1. 9ñ10 ñ Ventral valve internal mould, specimen SMF 65368. Locality: Etzbach/Sieg. Middle or Upper Siegen Formation, Middle or Upper Siegenian: 9 ñ ventral view, x1. 10 ñ lateral view, x1. 11ñ13 ñ Ventral valve internal mould, specimen SMF 59870. Locality: Etzbach/Sieg. Middle or Upper Siegen Formation, Middle or Upper Siegenian: 11 ñ ventral view, x1. 12 ñ lateral view, x1. 13 ñ muscle field with fine striations, x2.1. 14 ñ Ventral valve internal mould, specimen SMF 65875. Locality: Leingipfel, Taunus Hills, southern Rheinisches Schiefergebirge. Upper Tau- nusquarzit Formation, Middle or Upper Siegenian; x1.

Plate II Acrospirifer primaevus (Steininger, 1853) 1ñ8 ñ Dorsal valve internal mould and latex cast of it, specimen SMF 65868. Locality: Seifen, Westerwald area. Seifen Formation, Middle Siegenian: 1 ñ dorsal view of internal mould, x1. 2 ñ anterior view of internal mould, x1. 3 ñ posterior view of internal mould, x1. 4 ñ latex cast, x1. 5 ñ lateral view of internal mould, x1; 6. oblique view of internal mould, note median process and strongly developed notothyrial platform, x2; 7 ñ posterior view of internal mould, note median process, ctenophoridium, and dental sockets, x3.1. 8 ñ oblique view of latex cast showing cardinalia, note inner socket ridges and notothyrial platform, x2.6. 9 ñ Dorsal valve internal mould, specimen SMF 59874b. Locality: Seifen, Westerwald area. Seifen Formation, Middle Siegenian; x1. 10ñ12 ñ Dorsal valve internal mould, specimen SMF XVII 398a. Locality: M¸hlmerich, Westerwald area. Seifen Formation, Middle Siegenian: 10 ñ lateral view, x1. 11 ñ anterior view, x1. 12 ñ dorsal view, x1.

Plate III Acrospirifer primaevus (Steininger, 1853) 1ñ7 ñ Dorsal valve external mould and latex cast of it, specimen SMF 59874a. The external mould belongs to the internal mould figured on Pl. 2, Fig. 9. Locality: Seifen, Westerwald area. Seifen Formation, Middle Siegenian: 1 ñ external mould, overview, x2.5. 2 ñ external mould, detailed view showing minute holes left by micro-spines, x19. 3 ñ latex cast showing rows of micro-spines, anterior region of fold, x12. 4 ñ latex cast, anterior region of fold, x5.4. 5 ñ latex cast, detailed view of fourth plication clearly exhibiting rows of micro-spines, x25. 6 ñ latex cast, detailed view of interspace between third and fourth plication, several projecting micro-spines, some of them are broken off, x44. 7 ñ latex cast, overview, x5.1.

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U. Jansen: On the genus Acrospirifer Helmbrecht et Wedekind, 1923 (Brachiopoda, Lower Devonian) (Pl. I)

1 3

5 4

2

7

6

13

8

9

10

11 12 14

For explanation see p. 141

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U. Jansen: On the genus Acrospirifer Helmbrecht et Wedekind, 1923 (Brachiopoda, Lower Devonian) (Pl. II)

2

1

3

4 5

9 6

10

7

11

8 12

For explanation see p. 141

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U. Jansen: On the genus Acrospirifer Helmbrecht et Wedekind, 1923 (Brachiopoda, Lower Devonian) (Pl. III)

1

2

3

4

7

5 6

For explanation see p. 141

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