GEOLOGICA BELGICA (2017) 20/3-4: 181-188 Spirifer disjunctus (Sowerby, J. de C. in Sedgwick & Murchison, 1840) and S. verneuili Murchison, 1840 (Brachiopoda, Spiriferida): 175 years of confusion Paul SARTENAER P. Sartenaer passed away in July 2015, shortly after this paper was finalised. Since his retirement as Honorary Head of the Department of Palaeontology he continued working at the Royal Belgian Institute of Natural Sciences (RBINS), rue Vautier 29, B – 1000 Brussels, Belgium. ABSTRACT. ‘Spirifera disjuncta’ Soverby, J. de C in Sedgwick & Murchison, 1840 and ‘Spirifer Verneuili’ Murchison, 1840 were declared synonyms in 1840. ‘Spirifera disjuncta’ is based on a type series consisting of moulds of three specimens from the Upper Devonian of England: one from the Strunian of Barnstaple, North Devon, and two from the upper Famennian of Petherwin, North Cornwall. The type series of ‘Spirifer Verneuili’ is composed of three specimens from the Frasnian of Boulonnais, France. Lectotypes are designated herein. The acceptance of the synonymy of the two species, which still prevails, is considered unjustified. KEYWORDS: Spiriferids, England, Boulonnais (France), Upper Devonian. RÉSUMÉ. Spirifer disjunctus (Sowerby, J. de C. in Sedgwick & Murchison, 1840) et S. verneuili Murchison, 1840 (Brachiopoda, Spiriferida): 175 années de confusion. ‘Spirifera disjuncta’ Sowerby, J. de C. in Sedgwick & Murchison, 1840 et ‘Spirifer Verneuili’ Murchison, 1840 ont été déclarés synonymes en 1840. ‘Spirifera disjuncta’ est basé sur une série type comprenant les moules de trois spécimens du Dévonien supérieur d’Angleterre : un spécimen provient du Strunien de Barnstaple dans le nord du Devon, les deux autres du Famennien supérieur de Petherwin dans le nord des Cornouailles. La série type de ‘Spirifer Verneuili’ comprend trois spécimens du Frasnien du Boulonnais en France. Des lectotypes sont désignés dans ce travail. La synonymie acceptée des deux espèces prévaut encore à l’heure actuelle; elle est considérée injustifiée. MOTS-CLÉS: Spiriférides, Angleterre, Boulonnais (France), Dévonien supérieur. 1. Introduction Specimens studied are housed in the Sedgwick Museum of Earth Sciences, University of Cambridge (with specimen Judging by the number of descriptions (in tens), figures (in number prefixed: CAMSM) and in the Natural History tens), references (in hundreds), and citations (in thousands), Museum, London (formerly British Museum of Natural it seems evident that ‘Spirifera disjuncta’ Sowerby, J. de C. in History) (with specimen number prefixed: BMNH or Sedgwick & Murchison, 1840 is a well-known and universally NHMUK PAL BD). recognized species1. The reality is that 175 years elapsed since the species was 2. The identity card of disjunctus introduced, and, still, no single palaeontologist has attempted to come up with a proper definition of the species in its type area lato sensu (North Cornwall and North Devon). The three 2.1. The three specimens of the type series specimens of the type series, housed in the Sedgwick Museum The original description by Sowerby, J. de C. in Sedgwick of Earth Sciences, University of Cambridge since the species & Murchison (1840, pl. LIII, fig. 8, pl. LIV, figs 12, 13), was proposed, have never been mentioned in the literature. illustrated by the figures of the three specimens constituting Moreover, Sokiran (2013, p. 24) has been notified by Michael the type series is as follows: G. Bassett and Leonid E. Popov that the type series of this “Plate LIII, Fig. 8. ‘Spirifera disjuncta’. This, which is a cast of species was lost. the inside of the upper valve, appears to belong to the species In the year 1840, when the Devonian System came to light thus named, and is a good illustration of the internal structure in SW England, some new spiriferid species were established in of the genus, exhibiting the beak, the muscular impressions, Devon and Cornwall. Based on poorly preserved material and the central striated foramen (= cardinal process), and also the unsatisfactory descriptions and illustrations, these species led hinge area (= ventral hinge area) with its striated structure” to multiple and mostly vain discussions in the literature. One of them, ‘Spirifera disjuncta’, enjoyed worldwide distribution, (italics by the present author). and extended stratigraphic range in spite or probably on “Plate LIV, Figs. 12, 13. ‘Spirifera disjuncta’. Semicircular, account of its definition, rendered impossible without a type with an emarginate front, very convex, radiated; upper valve being designated among its type series. with about 12 ribs, much raised in the front, forming a rounded At the same time, the Devonian System was circumscribed elevation; ribs rounded, numerous, about 25 on each side the in continental Europe, and its upper part was undergoing active middle; beaks remote; hinge-area broad, curved, its edges investigations by British and French geologists in Boulonnais, nearly parallel. The specimens of this shell are so generally France. New spiriferid species were also established, but, distorted, that its true form is seldom to be clearly made out; contrary to the situation in England, their description by and this, added to the difficulty, which already exists of Murchison rested on well-preserved material. The same year, determining between the most perfect specimens of different one of them, ‘Spirifer Verneuili’, was declared identical to species, renders it very difficult to ascertain to what species ‘Spirifera disjuncta’. Equivalence of these two species, which they belong. Perhaps even the ‘S. gigantea’ from Tintagel won over the support of all renowned palaeontologists of (North Cornwall, 14 km to the northwest of Petherwin) (pl. that time and of the years after, is still surviving, although LV, figs 1 to 4) may be distorted individuals of this species” ‘Spirifer Verneuili’ later became the type species of the genus (italics by the present author). (Remark: it is evident that the Cyrtospirifer Nalivkin in Frederiks, 1924. Fallacy of this first half of the description can only apply to the specimen of equivalence is here put in evidence. fig. 13). 1 It has to be noted that species names which have been put between single quotation marks in the following, refer to the names used in the original description of the species. http://dx.doi.org/10.20341/gb.2017.010 182 P. S ARTENAER The three specimens of the type series of ‘Spirifera both (incomplete) valves is visible on three moulds. One of the disjuncta’ figured by Sowerby housed in the Sedgwick characteristics of the material of Petherwin is the occurrence Museum of Earth Sciences, University of Cambridge are: of large and very large complete or almost complete specimens CAMSM H.841 from Barnstaple, North Devon, and two that are only slightly deformed and look like rolling pebbles, specimens, CAMSM H.4008 and CAMSM H.4009, from both valves being strongly convex, worn out and glazed. Some Petherwin, North Cornwall. The specimen CAMSM H.841 of them (specimen BMNH 32965b, Pl. 2, Fig. G) have the (Pl. 1, Figs A-B) is the mould of an almost complete and large outline, profile and size of the paralectotype B. dorsal valve plus the interarea of the ventral valve (Fig. A = Most small specimens from Barnstaple and Petherwin have pl. LIII, fig. 8 of Sowerby; Fig. B represents internal cast of the greenish colour of the rock in which they are embedded, the specimen). The specimen is larger than hitherto estimated, others are brownish (most), grey, reddish, and, exceptionally, since part of the margin of its anterior part has been omitted rust-coloured. Surfaces of specimens from Petherwin are in the woodcut figured by Sowerby. Specimen CAMSM locally asphalt-black. H.4008 is the mould of a very large, flattened, distorted, and poorly preserved ventral valve (Pl. 2, Fig. A = pl. LIV, fig. 2.3. Stratigraphic range 12 of Sowerby), and specimen CAMSM H.4009 (Pl. 2, Figs When S. disjunctus was proposed as a new species, the B-F; Fig. B = pl. LIV, fig. 13 of Sowerby) is a large complete “calcareous slates” from South Petherwin and Barnstaple specimen (mould), less large than specimen CAMSM H.841. were considered by Sedgwick & Murchison (1840, pp. 668, 2.1.1. Designation of a lectotype 694-695) as having a “symmetrical position”, forming “an upper group of the great slaty series”, and appearing “on the Although the three specimens of the type series are very whole to form a mineral passage into the overlying system”. different from each other, no palaeontologist dealing with Recent knowledge indicates that these beds, in which spiriferids considered it necessary to designate a lectotype. disjunctus is declared to be found, are of different age. The choice of a lectotype has to be between the specimen The series of slates with thin limestones yielding the from Barnstaple and two specimens from Petherwin. spiriferids from South Petherwin form the late Famennian Specimen CAMSM H.841 (Pl. 1, Figs A-B) is here formally Upper Petherwin Beds (upper Platyclymenia and Clymenia designated as the lectotype of Spirifer disjunctus. As a fair “Stages”). representative of the abundant similar and slightly distorted The graded siltstones and shales with calcareous bands moulds from Barnstaple, it allows, in conjunction with them, and sandstones around Barnstaple that are rich in spiriferids to observe and define the internal characters of the species. correspond to the lower Pilton Formation, i.e. to the External characters, such as outline, costae, development of Wocklumeria Zone (probably the upper Wocklumeria Zone) fold, dorsal muscle field, and ventral interarea are also visible or to the upper Siphonodella praesulcata Zone in terms of on the specimen. conodont succession. These beds are commonly correlated 2.1.2. Paralectotypes with part or whole of the Stourscombe Beds overlying the Upper Petherwin Beds of North Cornwall, and, more Specimen CAMSM H.4008 (Pl. 2, Fig. A), here called generally, to the Strunian (Étroeungt Beds). paralectotype A, shows the ventral muscle field delimited by the dental plates.