identifier	taxonID	type	CVterm	format	language	title	description	additionalInformationURL	UsageTerms	rights	Owner	contributor	creator	bibliographicCitation
03ED0C5EFFD1FF9CFD97429A7864F83B.text	03ED0C5EFFD1FF9CFD97429A7864F83B.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Tarphyceratida Flower 1950	<div><p>Order Tarphyceratida Flower, 1950</p><p>Diagnosis (from Aubrechtová &amp; Korn 2025)</p><p>Multiceratoid cephalopods with coiled to gyroconic conchs of various whorl profile and simple transverse or slightly curved suture lines. Coiling planispiral, rarely torticonic; body chambers usually long, extending from a half to more than one complete whorl in length. Last whorl commonly slightly to greatly divergent from preceding coiled portions; terminal aperture commonly modified. Siphuncle varies in position; siphuncular segments tubular, nautilosiphonate, with orthochoanitic or loxochoanitic septal necks and thick connecting rings in stratigraphically earlier forms, and cyrtochoanitic septal necks and thin homogeneous rings in stratigraphically later forms. Muscle attachment scars ventromyarian or sometimes pleuromyarian. Thin cameral deposits present in some taxa. Shell surface smooth or ornamented with transverse lirae, ribs or annuli, or spiral ornament elements.</p><p>Families included</p><p>Barrandeoceratidae Foerste, 1925; Estonioceratidae Hyatt in Zittel, 1900; Ophioceratidae Hyatt, 1894; Plectoceratidae Hyatt in Zittel, 1900; Tarphyceratidae Hyatt, 1894; Trocholitidae Chapman, 1857 .</p></div>	https://treatment.plazi.org/id/03ED0C5EFFD1FF9CFD97429A7864F83B	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFDEFF93FDEF46057E48F979.text	03ED0C5EFFDEFF93FDEF46057E48F979.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Trocholitidae Chapman 1857	<div><p>Family Trocholitidae Chapman, 1857</p><p>Diagnosis (from Aubrechtová &amp; Korn 2025)</p><p>Family of the order Tarphyceratida with subglobular to discoidal conchs consisting of three to five or more gradually expanding volutions; body chamber may uncoil from preceding volution. Terminal aperture of body chamber with flares in some taxa, aperture often modified with ventral sinus and lateral projections. Whorl profile usually with dorsal imprint zone; usually depressed except for the adult growth stage that may have an equidimensional or compressed whorl profile; flanks and venter broadly rounded or flattened. Shell ornament varies during ontogeny, usually consisting of imbricating and/or frilled lirae, ribs or annuli, but taxa with smooth shell surface exist; ornament elements form ventral sinus. Conch in some taxa with periodic constrictions. Phragmocone chambers short (on average six phragmocone chambers relative to whorl height). Suture line simple with shallow ventral lobe or rarely saddle. Siphuncle subcentral, subdorsal or marginodorsal in position, ventral to central in initial volution; siphuncle segments tubular, weakly convex or weakly concavo-convex, narrow in diameter (usually less than 0.25 of apertural height); septal necks short (less than 0.20 of segment length), orthochoanitic or loxochoanitic; connecting rings usually thick, layered, but becoming thin and homogeneous in some taxa.</p><p>Genera included</p><p>Arkoceras Ulrich, Foerste, Miller &amp; Furnish, 1942; Crenuloceras Flower, 1968; Curtoceras Ulrich, Foerste, Miller &amp; Furnish 1942; Discoceras Barrande, 1867; Hardmanoceras Teichert &amp; Glenister, 1952; Jasperoceras Ulrich, Foerste, Miller &amp; Furnish, 1942; Litoceras Hyatt, 1884; Paradiscoceras Barskov, 1972; Plectolites Flower, 1968; Trocholites Conrad, 1838; Trocholitoceras Hyatt, 1894; Weberoceras Barskov, 1972; Wichitoceras Ulrich, Foerste, Miller &amp; Furnish, 1942; Yushanoceras Chen &amp; Liu, 1976 .</p><p>Remarks</p><p>Trocholitidae Schröder, 1891 is a junior homonym of Trocholitidae Chapman, 1857 and consequently, Chapman (1857) is the author of the family name.</p><p>Some authors have previously included Discoceras in the family Discoceratidae Dzik, 1984, which is, however, a junior homonym of Discoceratidae Hyatt, 1894 . The latter originally included several early Palaeozoic genera (besides Discoceras also Peismoceras Hyatt, 1894, Systrophoceras Hyatt, 1894, Trochoceras Barrande, 1848, Mitroceras Hyatt, 1894 and Plectoceras Hyatt, 1884), which have later been shown to belong to various, unrelated lineages. For example, the Silurian lechritrochoceratids Peismoceras and Systrophoceras represent basal members of the order Nautilida Agassiz, 1847 (Dzik &amp; Korn 1992; Manda &amp; Turek 2019). When all the unrelated genera are excluded, the family Discoceratidae is left with just Discoceras, the name-bearing taxon. However, the separation of Discoceras at the family level is not justified – the conch geometry, internal conch structures and ornament in Discoceras all perfectly fall within the morphological variability observed among the representatives of the family Trocholitidae . Thus, the family Discoceratidae Hyatt, 1894 is synonymised here with the family Trocholitidae Chapman, 1857 .</p></div>	https://treatment.plazi.org/id/03ED0C5EFFDEFF93FDEF46057E48F979	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFDEFF91FD8641B97985FC4D.text	03ED0C5EFFDEFF91FD8641B97985FC4D.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Discoceras Barrande 1867	<div><p>Genus Discoceras Barrande, 1867</p><p>Type species</p><p>Clymenia antiquissima Eichwald, 1842; by subsequent designation (Schröder 1891).</p><p>Diagnosis (after Kröger &amp; Aubrechtová 2018; Manda &amp; Turek 2018)</p><p>Genus of the family Trocholitidae with adult conch diameters between 40 and 150 mm or more; body chamber usually divergent from preceding whorl, aperture may be slightly constricted or ventrally flared; whorl profile weakly depressed, equidimensional or weakly compressed; shape of whorl profile circular, elliptic, subquadrate, trapezoidal or heart-shaped; whorls weakly embracing or not embracing; caecum subcentral, shifted towards ventral side, siphuncle shifts dorsally in second and third chamber, final dorsal or subdorsal position is attained in third septum; thick, layered connecting rings; shell surface smooth or ornamented with frilled and imbricated to lamellar lirae, narrow to strong annuli or ribs present in some taxa; ornament forms ventral sinus.</p><p>Remarks</p><p>Among the Ordovician Baltoscandian trocholitids, the genera most similar to Discoceras are Curtoceras Ulrich, Foerste, Miller &amp; Furnish 1942 and Trocholites Conrad, 1838 (see Aubrechtová &amp; Korn 2025 for detailed discussions). The species of both genera are smaller in adult diameters (usually between 20 and 60 mm), and their shells are more finely ornamented; the ornamentation elements are neither frilled nor strongly imbricated. In Curtoceras, the whorl profile is equidimensional or nearly so, with convex or only slightly flattened ventral and lateral sides. In Trocholites, the conch is stouter, more tightly coiled, the whorls embrace each other and the whorl profile is much more depressed.</p><p>In Discoceras, the adult conch size usually exceeds 100 mm, and the shell is ornamented with frilled and imbricated elements. The terminal body chamber is typically uncoiled to varying degrees. The adult growth stages of Discoceras are extremely discoidal (CWI &lt;0.35), and the whorls usually have only a weak imprint zone or no imprint zone at all. The whorl profile in Discoceras is typically weakly depressed in earlier growth stages (WWI = 1.00–1.50), becoming equidimensional or compressed in later growth (WWI = 0.50–1.00). The shape of the whorl profile ranges from circular or oval to subrectangular, subquadrate, trapezoidal or heart-shaped. Both the whorl profile WWI and its shape are highly variable within species and during ontogeny (Kröger 2025).</p><p>Geographic and stratigraphic occurrence</p><p>North America, Baltoscandia and St Petersburg Region of Russia, Kazakhstan, India, China, Middle–Late Ordovician. Baltoscandia, Czech Republic, North America, China and Australia, Llandovery–Wenlock series, Silurian.</p><p>Species included</p><p>North America (Meek &amp; Worthen 1870, 1873; Whiteaves 1897; Flower 1968): Lituites Graftonensis Meek &amp; Worthen, 1870; Lituites ? Ortoni Meek &amp; Worthen, 1873; Discoceras canadense Whiteaves, 1897; Discoceras perornatus Flower, 1968 .</p><p>Northern Europe and St Petersburg Region of Russia (Eichwald 1840; Saemann 1853; Lossen 1860; Remelé 1880, 1890; Schröder 1891; Hyatt 1894; Strand 1933; Balashov 1953; Sweet 1958; Kröger et al. 2011; Rasmussen &amp; Surlyk 2012; Manda &amp; Turek 2018; Kröger &amp; Aubrechtová 2019; Kröger 2025): Clymenia antiquissima Eichwald, 1840; Clymenia rarospira Eichwald, 1840; Lituites angulatus Saemann, 1853; Lituites arcuatus Lossen, 1860; Lituites danckelmanni Remelé, 1880; Discoceras bandonis Remelé, 1890; Trocholites Damesii Schröder, 1891; Schroederoceras saemanni Hyatt, 1894; Schroederoceras tubulatum Hyatt, 1894; Discoceras roemeri Strand, 1933; Discoceras spongistratum Balashov, 1953; Schroederoceras chrevitzaense Balashov, 1953; Schroederoceras gubkovense Balashov, 1953; Schroederoceras ievense Balashov, 1953; Schroederoceras tammikuense Balashov, 1953; Schroederoceras vasalemmense Balashov, 1953; Schroederoceras vesenbergense Balashov, 1953 Discoceras amplicameratum Sweet, 1958; Discoceras boreale Sweet, 1958; Discoceras depressum Sweet, 1958; Discoceras fleischeri Sweet, 1958; Discoceras siljanense Kröger et al. 2011; Discoceras costatum Rasmussen &amp; Surlyk, 2012; Discoceras vasegaardense Rasmussen &amp; Surlyk, 2012; Discoceras lindstroemi Manda &amp; Turek, 2018; Discoceras stridsbergi Manda &amp; Turek, 2018; Discoceras amtjaernense Kröger &amp; Aubrechtová, 2019; Discoceras nilssoni Kröger &amp; Aubrechtová, 2019; Discoceras paopense Kröger, 2025 .</p><p>Bohemia (Barrande 1865): Lituites (Ophioceras) amissus Barrande, 1865 .</p><p>Kazakhstan (Tarbagatay, East Kazakhstan) (Barskov 1972): Discoceras kazakhstanense Barskov, 1972; Discoceras tshingizense Barskov, 1972 .</p><p>China (Xainza, Tibet) (Lai 1982): Discoceras xainzaense Lai, 1982 .</p><p>China (Xinjiang) (Lai &amp; Wang 1981): Discoceras aqalense Lai &amp; Wang, 1981; Discoceras rareplicatum Lai &amp; Wang, 1981; Discoceras robustum Lai &amp; Wang, 1981; Discoceras semicirculare Lai &amp; Wang, 1981; Discoceras ventrosellatum Lai &amp; Wang, 1981; Discoceras yinganense Lai &amp; Wang, 1981 .</p><p>China (Shaanxi, Gansu, Ningxia) (Gao et al. 1982): Discoceras huanxianense Gao, Lai &amp; Wen, 1982 .</p><p>China (Altun area, Xinjiang) (Lai &amp; Wang 1986): Discoceras altunense Lai &amp; Wang, 1986 .</p><p>China (Mt Charchag, Xinjiang) (Lai 1987): Discoceras xinjiangense Lai, 1987 .</p><p>India (Spiti, Himachal Pradesh) (Salter in Reed 1912): Trocholites juliformis Salter, 1912 .</p></div>	https://treatment.plazi.org/id/03ED0C5EFFDEFF91FD8641B97985FC4D	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFDCFF95FDC744EF7CDAFA00.text	03ED0C5EFFDCFF95FDC744EF7CDAFA00.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Discoceras antiquissimum (Eichwald 1842)	<div><p>Discoceras antiquissimum (Eichwald, 1842)</p><p>Figs 4–6; Table 3</p><p>Clymenia antiquissima Eichwald, 1842: 33, pl. 3 figs 16–17.</p><p>Lituites trapezoidalis Lossen, 1860: 25, pl. 1 fig. 2.</p><p>Clymenia antiquissima – de Verneuil 1845: 361. — Eichwald 1860: 1301.</p><p>Lituites cornu arietites – Eichwald 1860: 1298.</p><p>? Discoceras antiquissimum – Rüdiger 1889: 55.</p><p>Lituites antiquissimus – Roemer 1861: 62, pl. 6 fig. 2f–g; 1885: 68(315), pl. 4(27) fig. 12.</p><p>Trocholites antiquissimus – Foord 1891: 51.</p><p>? Discoceras antiquissimum – Schröder 1891: (25)163.</p><p>Discoceras antiquissimum – Hyatt 1894: 500. — Foerste 1925: 17, 58, pl. 18 fig. 1. — Teichert 1930: 285. — Strand 1933: 33, pl. 2 figs 4, 11, pl. 4 figs 2–3, pl. 13 fig. 9. — Thorslund 1936: pl. 2 fig. 11 — Balashov 1953: 265, pl. 4 fig. 2, pl. 11 fig. 3, pl. 12 fig. 1; 1962: pl. 9 fig. 1; 1974: pl. 9 fig. 1. — Sweet 1958: 99, text-fig. 13Q. — Neben &amp; Krueger 1973: pl. 77 figs 24–25. — Dzik 1984: 42, text-fig. 9c–d, 12.39, pl. 7 fig. 1. — Kröger 2013a: 72 fig. 31b; 2025: 129 figs 47c–d, 48a, 49a, 50a.</p><p>Discoceras cf. antiquissimum – Balashov 1964: 48, pl. 3 figs 3a–b.</p><p>non Lituites antiquissimus – Roemer 1861: pl. 6 fig. 2a–e.</p><p>non Lituites antiquissimus – Roemer 1885: 68, pl. 4 fig. 12.</p><p>non Discoceras antiquissima – Hucke 1967: 58, pl. 15 fig. 1.</p><p>Diagnosis (after Strand 1933; Kröger 2013a, 2025; emended)</p><p>Species of the genus Discoceras with adult sizes of up to about 150 mm, WER ah ~ 1.90 (decreasing with ontogeny), whorl profile slightly depressed and becoming less depressed to equidimensional in maturity (WWI decreases from 1.50 to ~ 1.00 during ontogeny), broadly reniform in juvenile stages, rounded trapezoidal with venter wider than dorsum in later growth stages; suture line with ventral and lateral lobe and ventrolateral saddle; free adult body chamber with constriction near aperture; shell ornamented with prominent annuli, one to two annuli per distance between two septa; siphuncle close to dorsal conch margin, diameter 0.15–0.17 of whorl height in late growth stages, septal necks orthochoanitic.</p><p>Type material</p><p>Neotype (designated here) ESTONIA • Piirsalu old quarry (Lääne County); Pirgu Regional Stage, Katian Stage; illustrated in Fig. 4; TAM G432:72.</p><p>Other material examined</p><p>ESTONIA • 1 spec.; Hosholm (Vormsi Island, Lääne County); Pirgu Regional Stage (late Katian, Late Ordovician); 2007; Krueger leg.; MB.C.32314 • 1 spec.; Härgla Quarry (Rapla County); Porkuni Regional Stage, Hirnantian Stage; illustrated in Fig. 5A; TUG 1862-1 .</p><p>NORWAY • 1 spec.; Asker (Akershus County); Jerestadian Regional Stage (late Katian, Late Ordovician); von Buch Coll.; illustrated in Fig. 5B; MB.C.11569 .</p><p>Description</p><p>Neotype TAM G432:72 (Fig. 4) is an internal mould of a nearly complete conch in the adult growth stage, 151 mm in maximum diameter; the inner volutions are obscured by the rock. The body chamber is preserved in the length of ~55 degrees and it is uncoiled adaperturally. At the diameter of 145 mm, the conch is extremely discoidal (CWI = 0.21) with a whorl expansion rate (WER wh) of ~ 1.62. The whorl profile is roughly equidimensional (WWI ~ 1.00), weakly round laterally and slightly flattened ventrally. The ornament consists from prominent, widely spaced annuli (~ 16 mm apart in the last half whorl); their crests are rather sharp and adapically inclined. The annuli are oblique laterally and produce a deep and sharp sinus ventrally. The annuli are locally covered by fine transverse and longitudinal lirae. The suture lines are directly transverse and extend with a ventrolateral saddle and a lateral and ventral lobe. The relative cameral length (RCL) is ~ 0.25 in the last half volution.</p><p>Specimen TUG 1862-1 (Fig. 5A) is an internal mould of a conch in the subadult or adult growth stage, 109 mm in diameter, with locally preserved shell wall. One side of the conch is slightly worn resulting in the need to reconstruct whorl width, but otherwise, the specimen is not significantly deformed. A little over three, tightly coiled whorls are preserved, which are fully chambered; only the last ~ 24 degrees belong to the body chamber. At the maximum diameter, the conch is evolute (UWI = 0.50) and extremely discoidal (CWI ~ 0.29) with a whorl expansion rate (WER wh) of ~ 1.90. The whorl profile is slightly depressed (WWI ~ 1.07) and very weakly imprinted dorsally, rounded laterally and slightly flattened ventrally. The shell is ornamented with sharp and widely spaced annuli (~ 13 mm apart at dm = 109 mm); their crests are rather sharp and inclined towards the adapical part. The annuli run obliquely across the flanks and produce a sharp ventral sinus. Finer ornament elements are locally preserved, especially on the ventral side of the outer whorl. These fine elements are transverse lirae and very fine longitudinal lirae. The suture lines are directly transverse; they produce a ventrolateral saddle and a lateral and ventral lobe. The relative cameral length (RCL) is 0.18 at the dm = 104 mm).</p><p>Specimen MB.C.11569 is a conch in the subadult growth stage with a diameter of 81 mm and three preserved whorls (Fig. 5B). The conch is evolute (UWI = 0.53) and discoidal (CWI = 0.36) with moderate whorl expansion (WER ah = 1.82). The last whorl is weakly depressed (WWI = 1.36) and very weakly embracing (IZR = 0.02); the whorl profile is rounded trapezoidal in shape, being narrowest dorsolaterally and widest ventrolaterally. A short part of the body chamber is preserved; it is very slightly uncoiled from the preceding whorl. The shell is ornamented with distinct, widely spaced annuli (~ 11 mm apart at dm = 81 mm) with rounded, symmetrical crests, along with coarse lirae (up to 1 mm apart); the annuli have low nodes mid-ventrally and at the ventrolateral shoulder. Extremely fine longitudinal ornament is discernible at the ventral side at the end of the last whorl. The septa are relatively crowded (RCL = 0.15 at dm = 60 mm).</p><p>Specimen MB.C.32314 is a large, nearly adult conch with a diameter of 119 mm; only the outer whorl is preserved. The conch is extremely discoidal (CWI = 0.26) and evolute (UWI = 0.56), expanding with a WER ah of 1.71. The whorl profile at the maximum diameter of the conch is weakly depressed (WWI = 1.10) and trapezoidal in shape (widest ventrally); weakly imprinted dorsally or not imprinted (IZR = 0.02–0.00). The relative cameral length (RCL) is 0.22 (dm = 86 mm). The incomplete body chamber is preserved in the length of 100 degrees and uncoils from the preceding whorl at near its beginning. The siphuncle has a position close to the dorsal shell wall but its distance and the diameter cannot be precisely measured. The ornament consists of widely spaced annuli (~ 10 mm apart at dm = 87 mm) with rounded and symmetric crests.</p><p>Remarks</p><p>The holotype of Discoceras antiquissimum comes from the late Katian (Vormsi–Pirgu regional stages) of Kärdla (Island of Hiiumaa, Estonia). It was described by Eichwald (1840: 115), illustrated by Eichwald (1842: pl. 3 figs 16–17) and then re-illustrated by Foerste (1925: pl. 18 fig. 1) and Balashov (1953: pl. 12 fig. 1). The latter author stated the holotype was held at the “Prussian Geological Institute?” in Berlin. However, any attempts of the present authors to trace the current location and status of the specimen were unsuccessful and it is probable that the specimen was lost. For this reason, we designate TAM G432:72 (Fig. 4) from the Pirgu Regional Stage (Katian Stage) of west Estonia (Piirsalu old quarry, Lääne County) as the neotype. The specimen is roughly corresponds stratigraphically to the holotype and bears all the diagnostic features of the species, namely the coarse annulation on the shell surface. The specimen was previously described by Strand (1933: 34, pl. 2 fig. 11) and Kröger (2025: 132; under the obsolete collection number TAM G1:170), and is re-described and illustrated here for the purpose of neotype designation.</p><p>Specimen MB.C.11569 described above was originally used by Lossen (1860) to establish the species Lituites trapezoidalis . As already noted by Strand (1933: 36), the specimen corresponds in all aspects to the diagnosis of D. antiquissimum and is thus considered to represent an earlier growth stage attributable to the latter taxon.</p><p>Discoceras antiquissimum is similar to D. saemanni due to its weakly depressed, trapezoidal whorl profile, which is widest at the ventrolateral shoulder. However, it can be readily distinguished by the distinctly annulated shell surface; the annuli are clearly visible also on the internal mould. The thickness of the annuli varies between specimens, and the annuli are present in all growth stages except the earliest and latest growth stage (Kröger 2025).</p><p>Geographic and stratigraphic occurrence</p><p>Baltoscandia, north-eastern Russia, northern Germany and northern Poland; late Katian–early Hirnantian, Late Ordovician.</p></div>	https://treatment.plazi.org/id/03ED0C5EFFDCFF95FDC744EF7CDAFA00	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFD8FF8AFD9141117829F821.text	03ED0C5EFFD8FF8AFD9141117829F821.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Discoceras saemanni (Hyatt 1894)	<div><p>Discoceras saemanni (Hyatt, 1894)</p><p>Figs 6–8; Table 4</p><p>Schroederoceras Saemanni Hyatt, 1894: 462 .</p><p>Lituites angulatus Saemann, 1853: 166, pl. 21 fig. 1c–d.</p><p>Trocholites undosus Foord, 1891: 45 .</p><p>Discoceras hyatti Strand, 1933: 38, pl. 2 fig. 2, pl. 5 fig. 3a–b.</p><p>Discoceras sp. – Foerste 1930: 176, pl. 20 fig. 2a.</p><p>Discoceras saemanni – Strand 1933: 40, pl. 2 fig. 1a–b, pl. 4 fig. 1. — Sweet 1958: 102, text-fig. 13n. — Dzik 1984: 44, text-fig. 12.43. — Kröger 2025: 141, text-figs 48c, 49c, 50b, 51a, 53.</p><p>Discoceras hyatti – Sweet 1958: 102, text-fig. 13g.</p><p>Schroederoceras hyatti – Stumbur 1959: 26, text-fig. 1c; 1962: 137. — Dzik 1984: 44, text-fig. 12.44.</p><p>Schroederoceras saemanni – Stumbur 1962: 137.</p><p>Rectanguloceras sp. – Neben &amp; Krueger 1973: pl. 76 figs 16–17.</p><p>non Lituites angulatus Saemann, 1853: pl. 21 fig. 1a–b.</p><p>Diagnosis (after Kröger 2025)</p><p>Species of the genus Discoceras with adult conch diameters of up to ca 125 mm; adult WER ~2.00; adult whorl profile with WWI ~1.10–1.20, subtrapezoidal with flattened venter, venter considerably wider than dorsum except at adult aperture and in juvenile growth stages; WER and WWI decrease with conch size; free adult body chamber with constriction near aperture; ornamented with crenulated costae and distinct growth lines that form U-shaped hyponomic sinus, low ribs can occur.</p><p>Material examined</p><p>GERMANY – Brandenburg • 1 spec.; Hohensaaten; Vormsi or Pirgu regional stages (late Katian Stage, Late Ordovician); Stober leg.; illustrated by Neben &amp; Krueger (1973: pl. 76 figs 16–17), re-illustrated here in Fig. 7; MB.C.32315 .</p><p>POLAND – Pomerania • 1 spec.; Gdańsk; probably Late Ordovician; Rühle von Lilienstern Coll.; illustrated in Fig. 8; MB.C.32316 .</p><p>Description</p><p>Specimen MB.C.32315 is a conch of an adult individual, where a little less than one half is missing (Fig. 7). The maximum diameter is 102 mm; 3.25 whorls are preserved. The whorl width and profile had to be reconstructed due to the conch being embedded in rock on one side and the imprecise preparation of the specimen by a previous researcher. In the last half whorl, the conch is discoidal (CWI ~ 0.34) and increasingly evolute (UWI increases from 0.46 to 0.49); the coiling rate drops (WER decreases from 2.09 to 1.91), and the whorls are weakly embracing (IZR close to zero). The whorl profile is almost equidimensional (WWI = 0.96) and weakly trapezoidal in shape, with the widest point at the subangular ventrolateral shoulder. The sutures line has lateral and external lobes and a ventrolateral saddle. The body chamber is preserved over nearly 90 degrees of the whorl and is uncoiled from the preceding whorl. The end of the body chamber flares laterally, causing the whorl profile to change from trapezoidal to rectangular, with flattened dorsal and ventral sides. The relativa cameral length decreases during ontogeny, from RCL = 0.60 in the earliest whorl to 0.19 in the latest part of the phragmocone (dm = 72 mm). The initial chamber measures approximately 1.7 mm in length and 2.3 mm in width at the position of the first septum. The siphuncle is located close to the dorsal shell wall in the inner whorls and is nearly in contact with it in the outer whorl; the RSH is 0.20 at the largest preserved whorl height. The shell ornament in the earliest whorl is only very faintly preserved and appears to consist of widely and regularly spaced raised lirae or thin ribs. The second whorl has low, lamellar lirae and at the end of the body chamber, the raised lirae with symmetric crests are present.</p><p>Specimen MB.C.32316 is a nearly complete adult conch, broken off on one side (Fig. 8). The conch measures 96 mm in diameter, with a reconstructed maximum size of 120 mm, and consists of 3.25 whorls. In the last half-whorl, the conch becomes increasingly discoidal (CWI decreases from 0.34 to 0.29) and more evolute (UWI increases from 0.49 to 0.53), while the coiling rate decreases (WER drops from 1.99 to 1.82). The imprint zone rate (IZR) is close to zero. The whorl profile is weakly depressed (WWI decreases from 1.16 to 1.13) and weakly trapezoidal in shape, with the widest point at the subangular ventrolateral shoulder and a convex umbilical wall. The suture line extends with external and ventral lobes as well as a ventrolateral saddle. The last whorl begins to uncoil at approximately the rear part of the terminal body chamber or slightly earlier. The body chamber is 110 degrees in length, with a laterally flared aperture forming a ventral sinus. The relatice cameral length (RCL) is 0.25 in the last whorl. In the latest part of the phragmocone, the siphuncle is subdorsal, with an RSH of approximately 0.19. The shell ornament in the first whorl transitions from sharp, widely and regularly spaced raised lirae or thin ribs to low, lamellar lirae. The outer whorl bears fine lirae, either with symmetrical crests or imbricated, while very flat ribs appear at the end of the body chamber. A pair of very low, narrow ridges is present on the ventral shell surface of the last whorl.</p><p>Remarks</p><p>According to the original museum label, the specimen MB.C.32316 comes from the “Orthoceratite Limestone”, which would correspond to the Darriwilian Stage (Middle Ordovician). However, the lithology of the specimen indicates that the actual age is the Katian Stage (Late Ordovician). Additionally, no Darriwilian representatives of Discoceras exhibit a conch morphology similar to that of specimen MB.C.32316, suggesting that the stratigraphic information on the label is erroneous. Instead, specimen MB.C.32316 is almost identical to specimen MB.C.32315 and other late Katian–early Hirnantian representatives of Discoceras with a trapezoidal, ventrally flattened whorl profile. Its coiling parameters, ontogenetic trends and shell ornamentation perfectly align with the morphological variation recognised in D. saemanni by Kröger (2025); the two specimens are therefore assigned to that species.</p><p>Hyatt (1894) based D. saemanni on two specimens originally illustrated by Saemann (1853: pl. 21 fig. 1c–d). Both specimens come from the latest Katian of Herøya (near Porsgrund, Norway) and are now kept at the Museum of Comparative Zoology (Massachusetts, USA) under coll. no. MCZ:IP:109000 and MCZ:IP:109001. Neither of the syntypes were available for study in this work.</p><p>Discoceras saemanni is most similar to D. antiquissimum in terms of conch proportions, ratios and whorl profile, but its shell surface lacks annuli; instead, crenulated costae and, in some cases, low ribs are present. A weakly trapezoidal whorl profile is also present in specimens of the stratigraphically older (Sandbian) D. spongistratum, but the latter differs in shell ornamentation (narrow ribs or annuli), a more compressed whorl profile (WWI ~ 0.70) and a greater coiling rate (WER = 2.12) in the terminal growth stage.</p><p>Geographic and stratigraphic occurrence</p><p>Norway, Estonia, northern Germany and northern Poland; late Katian–Hirnantian Stage, Late Ordovician.</p></div>	https://treatment.plazi.org/id/03ED0C5EFFD8FF8AFD9141117829F821	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFC4FF88FD9646047829FB12.text	03ED0C5EFFC4FF88FD9646047829FB12.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Discoceras ievense (Balashov 1953)	<div><p>Discoceras ievense (Balashov, 1953)</p><p>Figs 6, 9; Table 5</p><p>Schroederoceras ievense Balashov, 1953: 259, pl. 9 fig. 1.</p><p>Discoceras ievesense – Sweet 1958: 112, pl. 12 figs 2–3, text-fig. 13h — Dzik 1984: 44.</p><p>Rectanguloceras ievense – Stumbur 1962: 137, 142.</p><p>Discoceras ievense – Kröger &amp; Aubrechtová 2018: 809, 811; 2019: 966.</p><p>Diagnosis (after Balashov 1953; Sweet 1958; emended)</p><p>Species of the genus Discoceras with adult sizes of about 110 mm; up to four tightly coiled whorls; last whorl discoidal with CWI ~0.30 and WER ah ~ 2.00. Whorl profile weakly imprinted dorsally, equidimensional (WWI ~ 1.00), convex in first two whorls but flattened laterally and ventrally (subquadrate) later in ontogeny. Suture line almost straight with broad and shallow ventral and lateral lobe. Shell ornamented with lirae on inner whorls, fine annuli are added on the last whorl, which are most pronounced on flanks. Siphuncle subdorsal with diameter ~ 0.20 of whorl height in late growth stages.</p><p>Material examined</p><p>ESTONIA • 1 spec.; Idavere; early Haljala Regional Stage (Sandbian Stage, Late Ordovician); Mark Coll; illustrated in Fig. 9; GIT 426-370 .</p><p>Description</p><p>Specimen GIT 426-370 is a tightly coiled conch in the subadult growth stage, with a maximum diameter of 66 mm (Fig. 9); a little over one whorl is preserved (minimum diameter ~ 30 mm). At a conch diameter of 54 mm, it is subevolute (UWI = 0.39) and discoidal (CWI = 0.31), with a high coiling rate (WER ah = 2.14). The conch is worn on one side, but it can be recognised that at smaller diameters, the whorl profile is very slightly compressed or equidimensional (WWI close to one), nearly square-shaped with flattened venter and flanks and very weakly embracing (IZR close to zero). In ontogenetically earlier stages of the conch, the flanks are more rounded, but the venter remains flattened; in the earliest visible whorl profile (at dm ~ 30 mm), the venter also appears rounded, with the whorl profile transitioning from nearly circular to nearly square-shaped during ontogeny. The shell ornament is preserved only in small remnants of the shell wall or as faint imprints on the internal mould of the outer whorl; it consists of irregularly thick lirae and/or low annuli. The siphuncle is positioned near the dorsal shell wall but is not in contact with it (subdorsal) and has a relative septal foramen height (RSH) of about 0.20. The septa are closely spaced with the RCL ranging between 0.15 and 0.20 in the outer whorl; the suture line is nearly straight, with only a very shallow lateral and external lobe.</p><p>Remarks</p><p>The holotype of Discoceras ievense was not accessible for study herein. It is the specimen illustrated by Balashov (1953: pl. 9 fig. 1), reportedly deposited under coll. no. 40 at the St. Petersburg State University. The holotype originates from the late Haljala Regional Stage (Sandbian Stage, Late Ordovician) of the Tallinn Region of Estonia.</p><p>Discoceras ievense is readily recognised from all other representatives of the genus by the square-shaped whorl profile with clearly flattened lateral and ventral sides in the outer two whorls and the relatively wide (RSH ~ 0.20), subdorsal siphuncle. The most similar species are D. rarospirum and D. vesenbergense from Estonia. In the late Darriwilian to Katian D. rarospirum, the whorl profile transitions from circular to trapezoidal (with wider dorsal side) and finally square-shaped, but the flanks of the conch remain rounded (Balashov 1953; Kröger &amp; Aubrechtová 2018, 2019). In the Katian (Rakvere Regional Stage) D. vesenbergense, the whorl profile has a flattened venter and flanks, but it is depressed, with the WWI decreasing from 1.35 to 1.08 (Balashov 1953; Kröger &amp; Aubrechtová 2018, 2019).</p><p>Geographic and stratigraphic occurrence</p><p>Northern Estonia and Norway (Oslo-Asker and Nes-Hamar districts); Sandbian Stage, Late Ordovician.</p></div>	https://treatment.plazi.org/id/03ED0C5EFFC4FF88FD9646047829FB12	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFC5FF8EFDE942057E69FE0A.text	03ED0C5EFFC5FF8EFDE942057E69FE0A.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Discoceras damesii (Schroeder 1891)	<div><p>Discoceras damesii (Schröder, 1891)</p><p>Figs 6, 10; Table 6</p><p>Trocholites Damesii Schröder, 1891: 158, pl. 28(5) fig. 2.</p><p>Schroederoceras Damesi – Hyatt 1894: 469–470 .</p><p>Discoceras damesi – Sweet 1958: text-fig. 13a.</p><p>Trocholites damesii – Neben &amp; Krueger 1971: pl. 39 figs 13–15.</p><p>Diagnosis</p><p>Species of the genus Discoceras in which the shell ornament on inner whorls has sharp, regularly spaced (up to 1 mm apart) and weakly frilled annuli or raised lirae, with symmetric crests, accompanied by extremely fine spiral ornament; shell in later whorls ornamented with irregularly frilled and strongly imbricated transverse elements. Whorl profile rounded, weakly depressed (WWI ~1.20); siphuncle near dorsal shell wall in subadult stage.</p><p>Type material</p><p>Holotype GERMANY – Brandenburg • Schwedt/Oder; Dalbyan Regional Stage (Sandbian Stage, Late Ordovician); illustrated by Schröder (1891: pl. 5(28) fig. 2) and Neben &amp; Krueger (1971: pl. 39 figs 13– 15), re-illustrated here in Fig. 10; MB.C.11542 .</p><p>Description</p><p>Holotype MB.C.11542 is a phragmocone in the juvenile or early adult growth stage, with a diameter of 56 mm and 2.5 whorls preserved (Fig. 10). The conch is embedded in rock on one side and broken off on the other; therefore, some ratios are estimates. At its largest diameter, the conch is discoidal (CWI ~0.42) and subevolute (UWI = 0.42), with a WER ah of 2.05. The whorl profile is elliptic and weakly depressed (WWI ~1.19). The imprint zone rate appears to increase in the last half-whorl (IZR from 0.00 to approximately 0.07). The siphuncle is positioned close to the dorsal shell wall (RSP ~0.12), with a relative septal foramen height (RSH) of 0.18. In the inner whorls, the shell is ornamented with rather sharp annuli or raised lirae, which are regularly and relatively widely spaced (up to 1 mm apart at dm = 24 mm), weakly frilled and not imbricated; the transverse elements are accompanied by an extremely fine spiral ornament. On the outer whorl, the transverse ornament becomes irregularly frilled and strongly imbricated, while spiral lines are no longer discernible.</p><p>Remarks</p><p>Discoceras damesii is a species of the genus in which the first 2.5 whorls are characterised by a weakly depressed, elliptic whorl profile and distinct shell ornament. The first at least 1.5 whorls show sharp annuli or raised lirae crossed by an extremely fine, flat spiral ornament. This transitions into irregularly thick, irregularly frilled, and strongly imbricated transverse elements, while spiral elements are no longer present.</p><p>The conch ratios and ornament of the holotype of D. damesii are rather similar to corresponding growth stages of the holotype of D. vesenbergense (Balashov 1953) and some representatives of D. saemanni (Kröger 2025: text-figs 50b, 53 and the specimen MB.C.32316 studied herein). However, it appears most similar to some specimens of D. roemeri (Kröger 2025), not only in whorl profile but particularly in the shell ornament, which transitions from thin, sharp ribs to frilled transverse elements. Further comparison is hindered by the insufficient details provided by Balashov (1953) and the lack of knowledge on the late growth stages of the holotype of D. damesii . Additionally, the latter is stratigraphically much older (Sandbian vs Katian to Hirnantian stages) than the representatives of the other three species named above. D. damesi is thus kept separate until more completely preserved material is known.</p><p>Geographic and stratigraphic occurrence</p><p>Northern Germany; Sandbian Stage, Late Ordovician.</p></div>	https://treatment.plazi.org/id/03ED0C5EFFC5FF8EFDE942057E69FE0A	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFC3FF8CFDEE45287856FBA3.text	03ED0C5EFFC3FF8CFDEE45287856FBA3.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Discoceras paopense Kroger 2025	<div><p>Discoceras cf. paopense Kröger, 2025</p><p>Figs 6, 11–12; Table 7</p><p>Material examined</p><p>ESTONIA • 1 spec.; Ristna cliff (Harju County); Keila Regional Stage (late Sandbian or early Katian Stage, Late Ordovician); Hints Coll.; illustrated in Fig. 11; GIT 789-6 • 1 spec.; Ristna (Hiiumaa Island); Keila Regional Stage (late Sandbian or early Katian Stage, Late Ordovician); illustrated in Fig. 12; GIT 426-443 .</p><p>Description</p><p>Specimen GIT 789-6 represents a subadult growth stage of a conch with a diameter of 98 mm with 1.5 volutions preserved (Fig. 11). The specimen is slightly worn on one side, and the inner whorls are damaged and compacted. In the last whorl, the conch is discoidal (CWI decreasing from 0.28 to 0.25) and evolute (UWI = 0.55). The coiling rate (WER ah = WER wh in this case) decreases from 2.01 to 1.75. The whorl profile is weakly imprinted dorsally (IZR close to zero) and transitions from compressed to equidimensional (WWI increases from 0.94 to 1.00), with convex flanks and a flattened venter. The penultimate whorl profile (dm = 53 mm) appears to be weakly trapezoidal, with a wider ventral side, though this may result from an oblique natural cut of the specimen. The relative cameral length (RCL) is approximately 0.20 of the corresponding whorl height in the last preserved whorl. The suture line extends with a lateral lobe, an external lobe and a ventrolateral saddle. At a diameter of 53 mm, the siphuncle is subdorsal (RSP = 0.32) with a relative septal foramen height (RSH) of 0.19.</p><p>Specimen GIT 426-443 is a conch in the subadult or adult growth stage, measuring 116 mm in diameter, with approximately three outer volutions preserved (Fig. 12). The specimen is broken off adaperturally and strongly compacted from one side. The innermost whorls cannot be measured, and the width and shape of the outer volutions can only be estimated from the unaffected flank. At the beginning of the last whorl, the conch is discoidal (CWI ~0.29 at dm ~ 85 mm) with an equidimensional whorl profile (WWI ~1.04 at dm ~ 85 mm), which appears convex laterally and either convex or very weakly flattened ventrally. In the last whorl, the coiling rate (WER wh) slightly increases from ~1.93 to 2.07 between a conch diameter of ~ 85–101 mm) before decreasing again from ~2.07 to 1.89 between a conch diameter of ~ 101–116 mm. At its greatest diameter, the conch is evolute (UWI ~0.52). The whorl profile in the last two whorls appears only very weakly imprinted dorsally or not imprinted (IZR close to zero). The relative cameral length (RCL) is approximately 0.20 of the whorl height in the last 1.5 whorls. The suture lines feature a lateral lobe, a ventral lobe, and a ventrolateral saddle. The siphuncle cannot be precisely measured, but it appears to be subdorsal, at least in the inner whorls. The shell ornament is best preserved on the compacted lateral side of the specimen. It consists of slightly irregularly spaced, oblique ribs or annuli, which appear rounded on top, with weaker transverse elements present between them. On the inner whorls, the ornament appears much finer, though this may be a result of the specimen’s preservation.</p><p>Remarks</p><p>The minor differences in whorl expansion rate between the two specimens are interpreted here as being due to inaccuracies in the measurements of the compacted specimen GIT 426-443 and differences in adult size. The conch geometry and ornament in both specimens are most similar to those seen in representatives of Discoceras paopense . However, both specimens are kept in open nomenclature due to incomplete preservation and compaction. Additionally, there is a stratigraphic gap between the specimens studied here (Keila Regional Stage) and representatives of D. paopense (Vormsi Regional Stage) .</p><p>Geographic and stratigraphic occurrence</p><p>Western Estonia; Keila Regional Stage, late Sandbian or early Katian Stage, Late Ordovician.</p></div>	https://treatment.plazi.org/id/03ED0C5EFFC3FF8CFDEE45287856FBA3	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFC1FF83FDCA4371796DFC2A.text	03ED0C5EFFC1FF83FDCA4371796DFC2A.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Discoceras gubkovense Balashov 1953	<div><p>Discoceras cf. gubkovense Balashov, 1953</p><p>Figs 13–14; Table 8</p><p>Material examined</p><p>GERMANY – Brandenburg • 1 spec.; Schwedt; Nabala Regional Stage (Katian Stage, Late Ordovician); illustrated in Fig. 13; MB.C.32317 .</p><p>Description</p><p>Specimen MB.C.32317 is a conch in the subadult or adult growth stage, measuring 100 mm in diameter (Fig. 13). In the final half whorl, the conch becomes increasingly discoidal (CWI decreasing from 0.32 to 0.21), more widely umbilicate (UWI increasing from 0.46 to 0.51), and less expanded (WER decreasing from 2.16 to 1.76). The whorl profile transitions from equidimensional to weakly compressed (WWI decreasing from 1.00 to 0.86) and from convex to flattened ventrally and laterally. The final whorl is not uncoiled, but the conch is distorted adaperturally, and it is unclear whether the aperture is preserved. The ornament consists of strongly imbricated lirae, which are irregularly raised to form narrow, transverse ribs.</p><p>Remarks</p><p>The conch geometry and ornament of specimen MB.C.32317 are similar to those of specimens of D. paopense from the Vormsi Regional Stage of Estonia. However, in MB.C.32317, the whorl profile transitions from equidimensional to weakly compressed and from convex to flattened ventrally and laterally, and the body chamber does not appear to uncoil.</p><p>Specimen MB.C.32317 more closely resembles the type specimens of D. gubkovense from the Sandbian Stage of the St. Petersburg Region of Russia as described by Balashov (1953). The similarities include an adult conch size of approximately 100 mm, an extremely discoidal conch shape, very slowly expanding and compressed whorls and shell ornamentation consisting of lirae and low ribs that form a ventral sinus. However, the type material of D. gubkovense described by Balashov (1953) is rather incompletely preserved and originates from a stratigraphically older interval (Sandbian vs Katian Stage). Additionally, internal features cannot be examined in MB.C.32317. As a result, the latter specimen is tentatively assigned to D. gubkovense with a question mark, pending further study.</p><p>Geographic and stratigraphic occurrence</p><p>Northern Germany; Nabala Regional Stage, Katian Stage, Late Ordovician.</p></div>	https://treatment.plazi.org/id/03ED0C5EFFC1FF83FDCA4371796DFC2A	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFCFFF85FD9146057826FB58.text	03ED0C5EFFCFFF85FD9146057826FB58.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Discoceras bandonis Remele 1890	<div><p>Discoceras bandonis Remelé, 1890</p><p>Figs 14–17; Table 9</p><p>Discoceras bandonis Remelé, 1890: 105, pl. 3 fig. 4.</p><p>Discoceras Bandonis – Schröder 1891: 24–25 (162–163).</p><p>Discoceras bandonis – Sweet 1958: 102, 106, text-fig. 13m. — Neben &amp; Krueger 1971: pl. 39 fig. 11.</p><p>Sweetoceras bandonis – Stumbur 1962: 137, 143.</p><p>Schroederoceras bandonis – Dzik 1984: 42, 44, text-fig. 12.42.</p><p>non Trocholites damesii – Neben &amp; Krueger 1971: pl. 39 figs 13–15.</p><p>Diagnosis</p><p>Species of the genus Discoceras with adult conch diameter of ~ 115 mm; conch extremely discoidal (CWI &lt;0.35) and evolute (UWI ~0.43); whorls weakly imprinted dorsally or not imprinted (IZR close to zero); whorl profile in the last whorl elliptic and weakly compressed (WWI ~ 0.90); whorl expansion rate decreases in ontogeny (WER = 2.6–2); relative cameral length (RCL) of ~ 0.17 in the last whorl; body chamber uncoiled, tubular or only slowly expanding, and short (up to 180 degrees in length); siphuncle position (RSP) of 0.23, relative septal foramen height (RSH) of ~0.20; shell ornament of fine, weakly frilled or flat and lamellar transverse lirae; flat, indistinct ribs may be present in late growth stages.</p><p>Type material</p><p>Holotype GERMANY – Brandenburg • Oderberg; Dalbyan Regional Stage (Sandbian Stage, Late Ordovician); 1881; Remelé Coll.; illustrated by Remelé (1890: pl. 3 fig. 4) and Neben &amp; Krueger (1971: pl. 39 fig. 11), re-illustrated here in Fig. 15; MB.C.11602 .</p><p>Additional material</p><p>ESTONIA • 1 spec.; unknown locality; late Haljala Regional Stage (Sandbian Stage, Late Ordovician); Mägi Coll.; GIT 426-128 • 1 spec.; Aluvere quarry (Lääne-Viru County); late Haljala Regional Stage (Sandbian Stage, Late Ordovician); GIT 426-144 • 1 spec.; Jõhvi-Paemurru quarry (Ida-Viru County); late Haljala Regional Stage (Sandbian Stage, Late Ordovician); Hermaküla Coll.; illustrated in Fig. 17; GIT 426-453 .</p><p>GERMANY – Mecklenburg-Vorpommern • 1 spec.; Salem (near Malchin); Moldåan Regional Stage (early Katian Stage, Late Ordovician); Krueger leg.; MB.C.32318 • 1 spec.; Schlicht (near Neustrelitz); Moldåan Regional Stage (early Katian Stage, Late Ordovician); Müller-Friedmann Coll.; MB.C.32319 .</p><p>POLAND – West Pomerania • 1 spec.; “Stettin” (now Szczecin); Moldåan Regional Stage (early Katian Stage, Late Ordovician); illustrated in Fig. 16; MB.C.11995 .</p><p>Description</p><p>Holotype MB.C.11602 is a tightly coiled phragmocone with a diameter of 102 mm, consisting of about three volutions, distorted from one side (Fig. 15). The conch is extremely discoidal (CWI = 0.32 at dm = 72 mm). In the last whorl, the umbilicus widens (UWI increases from 0.40 to 0.47) and the coiling rate (WER) decreases from 2.28 to 1.99). In the last half whorl, the whorl profile is elliptic and compressed (WWI increases from 0.85 to 0.94). The relative septal foramen height (RSH) is 0.17, and its position (RSP) is 0.23. The relative cameral length (RCL) is 0.20 at the maximum conch diameter. The shell is ornamented with relatively fine, weakly frilled, and generally regularly spaced transverse lirae that are not imbricated and form a ventral sinus.</p><p>Specimen MB.C.11995 is a conch of an adult individual with a diameter of 114 mm and 2.5 whorls preserved (Fig. 16). At a diameter of 100 mm, the conch is extremely discoidal (CWI = 0.29) and subevolute (UWI ~ 0.44) with a high coiling rate (WER = 2.11). The whorls are very weakly embracing (IZR close to zero). The whorl profile, at the maximum conch diameter, is weakly compressed (WWI = 0.93) and elliptic in shape. The body chamber is preserved over a length of 172 degrees and is uncoiled from the previous whorl; its profile is weakly compressed (WWI = 0.89) and elliptic, with a slight flattening on the dorsal side. The relative cameral length (RCL) in the last whorl is 0.18. The shell ornament is relatively fine and consists of increasingly frilled and lamellar lirae, irregular in thickness. The inner whorls of the conch appear to be out of the coiling plane, but this is only a result of preparation and gluing of the specimen by previous researchers.</p><p>Specimen MB.C.32318 is an adorally incomplete conch in the adult growth stage with a diameter of 115 mm; three whorls are preserved. The conch is subevolute (UWI ~0.42) with a high coiling rate (WER = 2.18). The imprint zone rate is close to zero. The whorl width cannot be accurately measured because one side of the specimen is distorted, but the whorl profile is apparently compressed and elliptic. The body chamber is preserved over a length of 120 degrees and is uncoiled from the previous whorl. The relative cameral length (RCL) in the last whorl is 0.14. The shell ornament is preserved only in a small area on the inner whorls; it consists of flat, strongly imbricated to lamellar lirae. The surface of the body chamber has faint impressions of flat, transverse rib-like elements.</p><p>Specimen MB.C.32319 is an incomplete coiled phragmocone in the subadult growth stage. The conch has a diameter of 87 mm; it is subevolute (UWI ~ 0.45) with a high coiling rate (WER = 2.00). The relative cameral length (RCL) is 0.18 at a diameter of 62 mm. The ornament consists of rather irregular lirae, increasingly frilled adaperturally; indistinct flat ribs are visible on the internal mould of the body chamber.</p><p>Specimen GIT 426-453 is a coiled phragmocone with a maximum measurable diameter of 117 mm (Fig. 17). The innermost whorls are covered by rock matrix, and the outermost whorl is adaperturally incomplete (only a short basal part of the body chamber is preserved). One side of the specimen is worn and slightly compacted, but the other side is mostly unaffected, which allows for the reconstruction of the whorl profile and some measurements. At a diameter of 96 mm, the conch is extremely discoidal (CWI = 0.25) and has a high coiling rate (WER = 2.00). The whorls are only slightly imprinted dorsally or not imprinted. The whorl profile is elliptic and compressed (WWI = 0.86 at dm = 96 mm). The siphuncle is relatively wide (RSH = 0.25) and has some distance from the dorsal shell wall (RSP = 0.25). The relative cameral length (RCL) in the last whorl decreases from 0.16 to 0.12; the suture line is nearly straight with only a shallow lateral lobe. The shell wall is not preserved, but imprints of oblique, irregularly raised ribs or annuli are visible in the last half a whorl.</p><p>Specimen GIT 426-144 is an incompletely preserved phragmocone with a diameter of 110 mm. The last half whorl is laterally compacted and worn, and thus, the conch geometry had to be reconstructed. Between a diameter of 63 and 96 mm, the conch is extremely discoidal (CWI ~0.25) and expands rapidly (WER decreases from 2.47 to 2.33). The whorls are either slightly dorsally imprinted dorsally or not imprinted. The whorl profile appears to be elliptic and compressed (WWI decreases from ~ 0.78 to 0.72). The relative cameral length (RCL) is approximately 0.15, and the suture line is straight with only a shallow lateral lobe. The shell wall is preserved in patches where fine, straight or weakly frilled lirae are visible; faint imprints of oblique, irregularly raised ribs or annuli can be discerned on the surface of the internal mould.</p><p>Remarks</p><p>Holotype MB.C.11602 was originally illustrated by Remelé (1890: pl. 3 fig. 4), but this illustration is rather inaccurate. It depicts the whorl profile as nearly circular in shape, whereas it is, in fact, compressed, with a whorl width index (WWI) of 0.85–0.94 in the last half whorl. Additionally, the ornament is not as well-preserved as the illustration suggests.</p><p>Discoceras bandonis is distinguished from other representatives of the genus primarily by its large, discoidal, evolute conch with a weakly compressed and elliptic whorl profile in the late growth stage, as well as by the rather fine, evenly developed lirae on the shell surface. Additionally, the body chamber appears to be relatively short, not exceeding 180 degrees in length.</p><p>The conch geometry, whorl profile, relative diameter and position of the siphuncle, shell ornament, and suture distance in the three Estonian specimens (GIT 426-128, GIT 426-144, GIT 426-453) closely match those of the specimens classified above as D. bandonis . Some differences in the coiling rate (WER) and whorl width index (WWI) are likely attributable to lateral compaction, partial distortion and the larger adult size of these specimens. In terms of adult size, the three specimens correspond to the holotype of D. tammikuense, which comes from stratigraphically coeval strata at Tammiku (near Jõhvi) in Estonia (Balashov 1953). The holotype of D. tammikuense differs from the three described specimens, as well as from all specimens of D. bandonis, in having a rectangular whorl profile with flattened lateral and ventral sides in the late growth stage (the earlier growth stages have an elliptic whorl profile; Balashov 1953), and a relatively narrower and more subdorsal siphuncle. However, it should be noted that the holotype of D. tammikuense was not available for this study; it cannot be ruled out that a physical examination would reveal that its conch geometry falls within the variation of D. bandonis . Furthermore, Balashov (1953) described Discoceras tammikuense var. chrevitzaense (Haljala Regional Stage, St Petersburg Region), which, according to him, differs only in having an elliptic whorl profile. This further supports the possibility that the three mentioned taxa may be synonymous.</p><p>In addition to the apparently closely similar D. tammikuense, the specimens of D. bandonis resemble representatives of D. circulare sp. nov.; however, in the latter, the whorl profile is circular in all growth stages, including the inner whorls.</p><p>Representatives of D. danckelmanni are also similar to those of D. bandonis, but the former species has a lower coiling rate (WER = 2.00 or less) with a more compressed whorl profile (WWI ~ 0.70 in the late growth stage); the body chamber appears to uncoil earlier in growth. However, the comparison of the two species is complicated by the poor preservation (compaction) of the types of D. danckelmanni .</p><p>Representatives of the two species from the Sandbian of the St Petersburg Region of Russia ( D. gubkovense and D. spongistratum) are more discoidal (CWI ~ 0.20), more compressed (WWI ~0.70 vs&gt; 0.90 in late growth stages) and have a whorl profile that is weakly flattened ventrally and laterally. Their terminal body chambers do not uncoil, and the shell ornament is much coarser (narrow ribs or annuli) compared to the fine lirae of D. bandonis . Additionally, in D. spongistratum, the whorl profile is wider on the ventral side than on the dorsal side (i.e., weakly trapezoidal). The holotype of D. gubkovense appears to have a much lower expansion rate, although this cannot be measured precisely based on the data provided by Balashov (1953).</p><p>Geographic and stratigraphic occurrence</p><p>Northern Germany, northern Poland, north-east Estonia; Sandbian–early Katian Stage, Late Ordovician.</p></div>	https://treatment.plazi.org/id/03ED0C5EFFCFFF85FD9146057826FB58	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFC8FFB9FDC943D9790BFEA7.text	03ED0C5EFFC8FFB9FDC943D9790BFEA7.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Discoceras danckelmanni (Remele 1880)	<div><p>Discoceras danckelmanni (Remelé, 1880)</p><p>Figs 14, 18–19; Table 10</p><p>Lituites Danckelmanni Remelé, 1880: 241, pl. 1 figs 7–8.</p><p>? Lituites (Trocholites) cornuarietis – Schmidt 1861: 199.</p><p>? Discoceras danckelmanni – Rüdiger 1889: 56. — Sweet 1958: 102, text-fig. 13f.</p><p>Discoceras (Lituites) Danckelmanni – Remelé 1890: 32, pl. 1 figs 7–8.</p><p>Discoceras Danckelmanni – Schröder 1891: 25 (163). — Hyatt 1894: 469.</p><p>Schroederoceras danckelmanni – Balashov 1953: 261, pl. 9 fig. 2.</p><p>Discoceras danckelmanni – Sweet 1958: 102, text-fig. 13f.</p><p>Rectanguloceras danckelmanni – Stumbur 1962: 137, 142.</p><p>? Schroederoceras danckelmani (sic) – Saladžius 1966: 36, pl.1 fig. 2.</p><p>Rectanguloceras (Discoceras) – Neben &amp; Krueger 1973: pl. 76 fig. 18.</p><p>non Discoceras danckelmanni – Hucke 1967: pl. 15 fig. 2.</p><p>non Rectanguloceras (Discoceras) danckelmanni – Neben &amp; Krueger 1973: pl. 65 figs 3–4.</p><p>Diagnosis</p><p>Species of the genus Discoceras with adult conch diameters of ~ 100 mm; adult conch evolute (UWI = 0.50–0.60), moderately expanding (WER ~2.00); whorl profile elliptic and compressed (WWI ~ 0.70 in late growth stage); body chamber uncoiled from preceding whorl for most of its length, nearly tubular in shape, only weakly curved and slightly flared ventrally in its apertural part; shell ornament with regularly spaced, weakly frilled lirae with symmetric crests, and irregularly spaced, low ribs on the body chamber.</p><p>Type material</p><p>Lectotype (designated herein) GERMANY – Brandenburg • Eberswalde; Moldåan Regional Stage (early Katian Stage, Late Ordovician); Remelé Coll.; illustrated by Remelé (1880: pl. 1 fig. 7; 1890: pl. 1 fig. 7), re-illustrated here in Fig. 18; MB.C.11603.</p><p>Paralectotype (designated herein) GERMANY – Brandenburg • 1 spec.; same data as for lectotype; illustrated by Remelé (1880: pl. 1 fig. 8) and Remelé (1890: pl. 1 fig. 8); MB.C.11570 .</p><p>Other material examined</p><p>GERMANY – Brandenburg • 1 spec.; Hohensaaten; Moldåan Regional Stage (early Katian Stage, Late Ordovician); Neben and Krueger Coll.; illustrated by Neben &amp; Krueger (1973: pl. 65, figs 3–4), re-illustrated here in Fig. 19; MB.C.32321. – Mecklenburg-Vorpommern • 1 spec.; Salem ( Malchin); Moldåan Regional Stage (early Katian Stage, Late Ordovician); MB.C.32320 .</p><p>Description</p><p>Lectotype MB.C.11603 is a conch in the adult growth stage with an uncoiled body chamber (Fig. 18). The specimen is strongly secondarily compressed, but some measurements can still be obtained. The diameter of the conch is around 100 mm in total, and it is evolute (UWI ~0.50). The whorls were probably weakly compressed, elliptic, and weakly imprinted dorsally or not imprinted. The coiling rate decreases in the last whorl from 2.10 to 1.94. The body chamber is tubular, about 104 degrees in length, and its departure from the previous whorl starts shortly after the last septum; the uncoiled part is weakly curved. The shell ornament is not preserved; only indistinct traces of some irregularly thick, flat transverse ornament elements are visible on the internal mould of the body chamber.</p><p>The ornament is much better preserved in paralectotype MB.C.11570 (Fig. 19). It consists of regularly spaced lirae, which are weakly frilled and have symmetric crests; in addition, low, rounded ribs are indicated ventrolaterally. The whorl profile in the paralectotype is not as strongly distorted as in the lectotype; it appears to be compressed (WWI = 0.70) and elliptic in shape.</p><p>Specimen MB.C.32320 is a compacted, fragmentary conch in the adult growth stage. The specimen shows the uncoiled body chamber, about 85 degrees in length, with a slightly flared ventral side.</p><p>Specimen MB.C.32321 is a nearly complete conch, consisting of over three whorls and with a maximum diameter of 93 mm. At this diameter, the conch is evolute (UWI = 0.61) and moderately expanding (WER = 1.98). The conch is embedded in rock from one lateral side, hence the whorl width cannot be measured. The shell wall is preserved only locally and bears fine, relatively regularly spaced transverse lirae. The relative cameral length (RCL) is about 0.20 in the last whorl; suture lines appear to be nearly straight or only with a shallow lateral and ventral sinus. The last 100 degrees of the conch are occupied by the body chamber, which is uncoiled from about the last septum and is nearly tubular in shape; the uncoiled part is weakly curved and almost straight.</p><p>Remarks</p><p>Discoceras danckelmanni was described by Remelé (1880) based on two distorted (compacted) specimens. Additionally, the type specimens are not accurately illustrated by Remelé (1880, 1890); the ornamentation is only faintly preserved, and the specimens do not show the siphuncle or septa. Since the specimens are compacted, the whorl profile is not as strongly compressed as indicated by Remelé (1880, 1890) and Sweet (1958: text-fig. 13f).</p><p>Despite the poor preservation of the type material, some measurements and descriptions could still be made, and two other specimens, MB.C.32320 and MB.C.32321 from the herein studied collection, were assigned to the species.</p><p>Discoceras danckelmanni can be distinguished from other species of the genus by its large, discoidal conch. The body chamber is probably rather short, with a low expansion rate, and remains nearly tubular except for a slight ventral flaring in its apertural region. The whorls are also relatively slowly expanding and have an elliptic and weakly compressed profile. Most similar to D. danckelmanni is D. bandonis, in which the whorl profile is less compressed (WWI ~0.90 vs 0.70) and which has a higher coiling rate (WER of 2.00 in late growth stage); its body chamber uncoils from the previous whorl at about midlength or later.</p><p>The holotypes of three species from the Haljala Regional Stage (Sandbian) of Estonia and the St Petersburg Region of Russia ( D. tammikuense, D. gubkovense, and D. spongistratum) are also similar to the specimens of D. danckelmanni . All three of these species have rather large (95–145 mm), discoidal and slowly expanding conchs (WER ~ 2.00) with weakly subrectangular, subtrapezoidal, or elliptic, compressed whorl profiles (WWI = 0.70–0.80), and their shells are ornamented with lirae and/or low ribs. In contrast to the specimens of D. danckelmanni, only the adapertural end of the body chamber is uncoiled in D. tammikuense, while in D. gubkovense and D. spongistratum, the body chamber is not uncoiled at all.</p><p>The specimens of D. paopense are larger in adult size (120 mm vs 100 mm) than D. danckelmanni, and the whorl profile appears less compressed (WWI 0.80–0.90 vs ~ 0.70) with a flattened venter; the body chamber uncoils later in ontogeny.</p><p>Geographic and stratigraphic occurrence</p><p>Northern Germany and northern Estonia; early Katian Stage, Late Ordovician.</p></div>	https://treatment.plazi.org/id/03ED0C5EFFC8FFB9FDC943D9790BFEA7	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFF4FFBFFDBD4674793CFE2F.text	03ED0C5EFFF4FFBFFDBD4674793CFE2F.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Discoceras aseriense Aubrechtová & Korn & Kröger 2026	<div><p>Discoceras aseriense sp. nov.</p><p>urn:lsid:zoobank.org:act: 7E00DA96-8FBD-4160-996E-B0EA30BECF3E</p><p>Figs 14, 20; Table 11</p><p>Diagnosis</p><p>Species of the genus Discoceras with an adult conch diameter of about 90 mm, terminal body chamber uncoiled. Conch in the last half whorl thinly discoidal (CWI ~0.30) and evolute (UWI ~0.50) with WER of ~ 1.75 in late growth stage. Whorl profile not imprinted dorsally, weakly depressed (WWI ~ 1.10) with rounded or slightly flattened venter and flanks. Phragmocone chambers with RCL ~ 0.25 in last whorl. Suture line straight on the venter or with a shallow ventral and lateral lobes. Shell on inner whorls ornamented with fine lirae, and in the last whorl with regularly spaced, narrow, rounded ribs or flat annuli.</p><p>Etymology</p><p>From ‘Aseri’, referring to the type horizon.</p><p>Type material</p><p>Holotype ESTONIA • Koila (Lääne-Viru County); Aseri Regional Stage (Darriwilian Stage, Middle Ordovician); Schmidt Coll.; illustrated in Fig. 20; GIT 225-1084 .</p><p>Description</p><p>Holotype GIT 225-1084 is an adaperturally uncoiled phragmocone in the adult growth stage, with a total diameter of approximately 90 mm; the last 2.5 whorls are preserved (Fig. 20). The body chamber is preserved over a length of about 120 degrees and becomes uncoiled from the phragmocone after about 100 degrees (at a coiled diameter of ~ 82 mm). In the last half whorl, the conch is discoidal (CWI = 0.27) and evolute (UWI increases from 0.48 to 0.52), with a coiling rate (WER) of 1.76 at dm = 82 mm. The whorls are not imprinted dorsally; the whorl profile is weakly depressed to equidimensional (WWI = 1.05), appearing slightly flattened on the ventral side. The relative cameral length (RCL) is 0.25 in the last whorl, with the final phragmocone chambers shortened. The suture line exhibits shallow ventral and lateral lobes. The shell ornament is preserved on the inner whorls, where it consists of fine lirae, and locally on the body chamber, where it comprises rather regularly spaced, narrow, rounded ribs or annuli.</p><p>Remarks</p><p>With its occurrence in the Aseri Regional Stage, the holotype of Discoceras aseriense sp. nov. represents the stratigraphically oldest known representative of Discoceras from Baltica, predating the Lasnamägian D. depressum of Norway and the Uhakuan D. rarospirum of Estonia, if not globally.</p><p>Among other species, the holotype of D. aseriense sp. nov. appears to be most similar in conch geometry and shell ornamentation to a late Darriwilian or early Sandbian specimen from Norway, which Sweet (1958: pl. 8 fig. 7) assigned to “ Discoceras arcuatum ?”. However, it is difficult to compare the two based on the available information and the limited data on the internal whorls and siphuncle. Moreover, the validity of D. arcuatum has been questioned (Rasmussen &amp; Surlyk 2012), as both type specimens were likely lost during World War II. Therefore, this matter remains unresolved until more complete specimens are available to allow proper taxonomic assignments.</p><p>The other Darriwilian representatives of Discoceras differ from the holotype of D. aseriense sp. nov. more significantly. The holotype of D. depressum has a depressed whorl profile even in the late ontogenetic stage (WWI ~1.35). The representatives of D. rarospirum do not uncoil adaperturally. The specimens of D. boreale have shorter phragmocone chambers (RCL 0.14–0.20 vs 0.25), and the whorl profile becomes slightly compressed in later growth stages (WWI = 0.90).</p><p>The other Darriwilian representatives of Discoceras differ from the holotype of D. aseriense sp. nov. more significantly. The holotype of D. depressum has a depressed whorl profile even in late ontogenetic stages (WWI ~ 1.35). The representatives of D. rarospirum do not uncoil adaperturally. The specimens of D. boreale have shorter phragmocone chambers (RCL 0.14–0.20 vs 0.25) and the whorl profile is becomes slightly compressed in growth (WWI = 0.90 in late ontogeny).</p><p>Among the specimens studied herein, the holotype of D. aseriense sp. nov. is most similar to specimen MB.C.32328 (D. sp. indet.). However, at a diameter of 70 mm, the whorl profile in MB.C.32328 is weakly subquadrate with a convex venter and slightly flattened flanks. The shell ornamentation in the outer whorl of the holotype appears more distinctly and regularly developed. The two specimens are difficult to compare, however, due to the incomplete preservation of MB.C.32328 and the lack of information on the whorl profile and siphuncle in the holotype of D. aseriense . Additionally, the two specimens are significantly separated stratigraphically (Aseri vs Haljala Regional Stages), which is a further argument for keeping them separate until better-preserved material is available.</p><p>Geographic and stratigraphic occurrence</p><p>Northern Estonia; Aseri Regional Stage, Darriwilian Stage, Middle Ordovician.</p></div>	https://treatment.plazi.org/id/03ED0C5EFFF4FFBFFDBD4674793CFE2F	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFF2FFBDFDEF450D7E04FEA6.text	03ED0C5EFFF2FFBDFDEF450D7E04FEA6.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Discoceras brandenburgense Aubrechtová & Korn & Kröger 2026	<div><p>Discoceras brandenburgense sp. nov.</p><p>urn:lsid:zoobank.org:act: 26674E19-CF3F-4E2C-B25C-A42F123EE5BF</p><p>Figs 14, 21; Table 12</p><p>Rectanguloceras cf. roemeri – Neben &amp; Krueger 1973: pl. 65 figs 1–2.</p><p>Discoceras roemeri – Kröger 2013a: 73.</p><p>Diagnosis</p><p>Species of the genus Discoceras with an adult conch diameter of about 80 mm. Conch tightly coiled up to diameter of about 64 mm; body chamber and adapertural part of phragmocone widely uncoiled. Conch increasingly discoidal (CWI decreases from 0.40 to 0.30 in last three quarters of a whorl) with decreasing coiling rate (WER wh decreasing from 2.50 to 2.00). Whorl profile subcircular, equidimensional to weakly depressed (WWI ~ 1.05) in last whorl but equidimensional and slightly ventrally flattened in body chamber. Phragmocone chambers short (RCL = 0.18 in last whorl), suture line with broad lateral lobe, straight across venter.</p><p>Etymology</p><p>From Brandenburg (Germany), the region of the type locality.</p><p>Type material</p><p>Holotype GERMANY – Brandenburg • Niederfinow; Moldåan Regional Stage (early Katian Stage, Late Ordovician); Neben Coll.; illustrated in Fig. 21; MB.C.32324.</p><p>Description</p><p>Holotype MB.C.32324 is a conch with a maximum diameter of 82 mm; approximately 3.25 whorls are preserved, with the last ~100 degrees of the outer whorl being uncoiled (Fig. 21). The coiled portion has a diameter of about 64 mm. In the last three-quarters of a whorl, the conch becomes increasingly discoidal (CWI decreases from 0.38 to 0.31) and increasingly evolute (UWI increases from 0.41 to 0.48), while the coiling rate (WER) decreases from 2.51 to 1.97. The whorl profile is nearly circular, transitioning from equidimensional to slightly depressed (WWI increases to 1.03 to 1.08) throughout the last whorl, before becoming equidimensional again at the end of the body chamber, with a slightly flattened venter. The body chamber is preserved over a length of approximately 90 degrees; it is tubular in shape, with only a slightly flared venter. The phragmocone chamber length (RCL) is 0.18 in the last whorl. The shell ornament is preserved only in a small area on the venter at the end of the last whorl, where it consists of fine lirae.</p><p>Remarks</p><p>Holotype MB.C.32324 is unique among the species of Discoceras due to its comparatively small adult conch diameter of 82 mm. It is widely uncoiled, slowly expanding last volution, has an equidimensional or slightly depressed whorl profile that is ventrally slightly flattened, and shows the presence of short phragmocone chambers.</p><p>Neben &amp; Krueger (1973) classified holotype MB.C.32324 as “ Rectanguloceras (Discoceras) cf. roemeri ” (see also Kröger 2013a). However, the terminal conch of D. roemeri is much larger (up to 150 mm in diameter) with an elliptic, depressed to quadrangular whorl profile. In D. roemeri, the last whorl uncoils from the preceding whorl only at the very end of the body chamber, whereas it is much more widely uncoiled in holotype MB.C.32324. Additionally, the phragmocone chambers are longer in D. roemeri (RCL ~ 0.25 vs ~ 0.18 in the last whorl).</p><p>Holotype MB.C.32324 is similar in umbilical width, conch width and expansion rate to the holotype of D. polonicum sp. nov. (MB.C.11992); the latter also has an uncoiled outer whorl. However, the whorl profile in MB.C.11992 is compressed (WWI ~ 0.90 in the last volution) and ventrally rounded. Additionally, the last 90 degrees of the conch expand more rapidly in MB.C.11992 (WER = 2.27–2.15 vs 2.04– 1.97 in MB.C.32324).</p><p>Geographic and stratigraphic occurrence</p><p>Northern Germany; early Katian Stage, Late Ordovician.</p></div>	https://treatment.plazi.org/id/03ED0C5EFFF2FFBDFDEF450D7E04FEA6	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFF0FFBCFDB1467B784CFAF8.text	03ED0C5EFFF0FFBCFDB1467B784CFAF8.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Discoceras angustum Aubrechtová & Korn & Kröger 2026	<div><p>Discoceras angustum sp. nov.</p><p>urn:lsid:zoobank.org:act: A67ACC33-C790-4987-A16C-FBE9797AC8EE</p><p>Fig. 22</p><p>Diagnosis</p><p>Species of the genus Discoceras with adult conch diameter of 70 mm or more; conch extremely discoidal (CWI ~ 0.30) and evolute (UWI ~0.45); whorls weakly imprinted dorsally or not imprinted (IZR close to zero); whorl profile changes from nearly equidimensional (WWI ~1) to weakly depressed (WWI ~ 1.10) with convex flanks and slightly flattened venter; whorl expansion rate increases up to WER ~2.3 at ~ 50 mm conch diameter; relative cameral length (RCL) of 0.14 in the last whorl; shell ornament with low and irregularly thick transverse ribs; fine spiral elements in early growth stage.</p><p>Etymology</p><p>From the Latin ‘angustum’ (adj., neut.) = ‘narrow’, referring to the remarkably short phragmocone chambers.</p><p>Type material</p><p>Holotype ESTONIA • Rakvere (Lääne-Viru County); Keila Regional Stage (late Sandbian or early Katian Stage, Late Ordovician); illustrated in Fig. 22; TUG 2-731.</p><p>Description</p><p>Holotype TUG 2-731 is an internal mould of a conch in the subadult or adult growth stage, embedded in the rock matrix on one side (Fig. 22). Internal structures are almost entirely destroyed, but some whorl profiles can be partially reconstructed. The conch has a diameter of 70 mm, with two outer volutions visible. In the last 1.5 whorls, the whorl profile transitions from nearly equidimensional (WWI = 0.97 at whorl height of 9 mm) to weakly depressed (WWI = 1.12 at a whorl height of 21 mm), subquadrate in shape, with convex flanks and an apparently slightly flattened venter. The coiling rate (WER) increases from 1.87 to 2.28, while the conch width index (CWI) increases from 0.27 to 0.33. At its maximum diameter, the conch is evolute (UWI = 0.45). At a whorl width of 9 mm, the siphuncle is positioned close to the dorsal shell wall and has a relative septal foramen height (RSH) of 0.18. The phragmocone chambers are markedly short, with a relative cameral length (RCL) of about 0.14 of the respective whorl height in the last whorl. The suture lines form shallow lateral and ventral lobes. The internal mould shows traces of strongly oblique, low, and irregularly thick transverse ornament elements. Additionally, fine spiral elements are discernible on the flank of the innermost preserved whorl.</p><p>Remarks</p><p>The flanks of the outer volution of the conch in specimen TUG 2-731 have a shallow impression with a series of thin grooves, measuring up to 6 mm in total width. Similar structures have been described in coiled cephalopods before and interpreted as evidence of conch damage during earlier ontogeny (Manda &amp; Turek 2018; Aubrechtová &amp; Korn 2025), as a colour band (Kröger &amp; Aubrechtová 2019), or as a type of ornament produced by the elevation of costae (Kröger 2025). However, the shell wall is not preserved in specimen TUG 2-731, and it is unclear how this lateral band manifests on the shell surface. Therefore, further interpretation is avoided here.</p><p>It appears that the ontogenetic trajectories of several characters in TUG 2-731 are rather unique. The whorl profile becomes more depressed, and the expansion rate increases during growth. The latter may indicate that the specimen does not yet represent the adult growth stage.</p><p>Specimen TUG 2-731 differs from all other representatives of Discoceras with subquadrate or weakly depressed whorl profiles, such as D. vesenbergense and D. roemeri, in possessing very short phragmocone chambers and fine spiral ornamentation in the early growth stage.</p><p>Geographic and stratigraphic occurrence</p><p>Northern Estonia; Keila Regional Stage, late Sandbian or early Katian Stage, Late Ordovician.</p></div>	https://treatment.plazi.org/id/03ED0C5EFFF0FFBCFDB1467B784CFAF8	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFF1FFB2FDBB423F79E6FC54.text	03ED0C5EFFF1FFB2FDBB423F79E6FC54.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Discoceras circulare Aubrechtová & Korn & Kröger 2026	<div><p>Discoceras circulare sp. nov.</p><p>urn:lsid:zoobank.org:act: E909E2E3-131A-4015-8856-5F94EAB67E91</p><p>Figs 23–24; Table 13</p><p>Diagnosis</p><p>Species of the genus Discoceras with adult conch diameter of over 100 mm; conch extremely discoidal (CWI ~ 0.30) and subevolute (UWI ~0.40); whorls weakly imprinted dorsally or not imprinted (IZR close to zero); whorl profile remains nearly equidimensional (WWI ~1.00) with convex flanks and venter; whorl expansion rate decreases in ontogeny up to WER ~2.10; relative cameral length (RCL) of 0.25 in the last whorl; body chamber slightly uncoiled adaperturally and slightly flared; siphuncle subdorsal with a relative septal foramen height (RSH) of ~ 0.20 in the last whorl; shell ornament of fine, regularly spaced lirae which are not frilled or weakly frilled and weakly imbricated.</p><p>Etymology</p><p>From the Latin ‘circulare’ (adj., neut.) = ‘circular’, referring to the shape of the whorl profile.</p><p>Type material</p><p>Holotype ESTONIA • Aluvere quarry (Lääne-Viru County); late Haljala Regional Stage (Sandbian Stage, Late Ordovician); illustrated in Fig. 24; GIT 426-145.</p><p>Paratype GERMANY – Brandenburg • Schlabendorf (near Calau); early Haljala regional Stage (Sandbian, Late Ordovician); Krueger Coll.; MB.C.32325 .</p><p>Description</p><p>Holotype GIT 426-145 is a conch of a nearly adult or adult individual with a maximum diameter of 102 mm (Fig. 24). The last 2.25 whorls are preserved; the conch is adaperturally incomplete, with at least 90 degrees of the outermost volution missing and indicated only by remains on the outer surface of the penultimate whorl. During growth, the conch is discoidal (CWI decreases from 0.46 to 0.34) and moderately evolute (UWI increases from 0.28 to 0.41). The coiling rate (WER) decreases from 2.83 at a diameter of 34 mm to 2.13 at a diameter of 83 mm. The whorl profile is weakly imprinted dorsally, subcircular, and equidimensional (WWI ~1.00). The siphuncle has a subdorsal position and a relative septal foramen height (RSH) of about 0.19. The shell ornament consists of well-developed transverse lirae, which are regularly spaced and not frilled or only weakly frilled. In the last half whorl, the lirae are irregularly thickened, with very fine lines present between thicker lines, and low, rounded annuli are indicated.</p><p>Paratype MB.C.32325 is a conch in the adult growth stage with a diameter of 105 mm with the last 2.5 volutions preserved. The conch is extremely discoidal (CWI = 0.31) and subevolute (UWI = 0.43) with a high coiling rate (WER = 2.19). At its largest diameter, the whorl profile is subcircular and nearly equidimensional (WWI = 0.97). The body chamber is preserved over 95 degrees and becomes uncoiled after about 70 degrees. It appears to be adaperturally slightly flared on its ventral and lateral sides, with a slight indication of a ventral sinus. However, it is not clearly visible whether the aperture is preserved. The relative cameral length (RCL) is 0.25 at dm = 70.9 mm. The ornament consists of regularly spaced lirae, which are not frilled or only weakly frilled and slightly imbricated.</p><p>Remarks</p><p>The holotype and paratype of Discoceras circulare sp. nov. are most similar to specimens assigned to Discoceras bandonis, but they differ in having a more circular whorl profile (WWI ~ 1.00 vs 0.93 at the corresponding conch diameter).</p><p>The conch geometry in the representatives of Discoceras circulare sp. nov. falls within the variability described for the late Katian to early Hirnantian D. roemeri (Kröger 2025) . However, D. roemeri differs in having a greater adult size (140 mm), a subquadratic whorl profile in subadult growth stages, and a stronger ornamentation consisting of imbricated lamellae, irregularly spaced costae, and shallow ribs.</p><p>Geographic and stratigraphic occurrence</p><p>Northern Germany, Estonia; Haljala Regional Stage, Sandbian Stage, Late Ordovician.</p></div>	https://treatment.plazi.org/id/03ED0C5EFFF1FFB2FDBB423F79E6FC54	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFFCFFB0FDAB46057E04FA53.text	03ED0C5EFFFCFFB0FDAB46057E04FA53.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Discoceras sovaki Aubrechtová & Korn & Kröger 2026	<div><p>Discoceras sovaki sp. nov.</p><p>urn:lsid:zoobank.org:act: 4A540D1B-F7B7-4638-827F-336D8CD3EAB0</p><p>Figs 23, 25; Table 14</p><p>Rectanguloceras (Discoceras) danckelmanni – Neben &amp; Krueger 1973: pl. 65 figs 3–4.</p><p>Diagnosis</p><p>Species of the genus Discoceras with adult conch size of ~ 70 mm, of which the coiled part is ~ 55 mm in diameter; body chamber uncoils from about half of its length onward; whorl profile in external volution weakly compressed (WWI between 0.78 and 0.86), barely imprinted dorsally (IZR close to zero or zero), and elliptic in shape, slightly ventrally flattened from the base of the body chamber; shell ornament of sharp, raised lirae or thin annuli, evenly spaced, slightly imbricated with fine lirae or growth lines in between them.</p><p>Etymology</p><p>In honour of the late Jan Sovák (1953–2025), Czech painter renowned for vivid reconstructions of prehistoric life, including early Palaeozoic cephalopods.</p><p>Type material</p><p>Holotype GERMANY – Brandenburg • Prenzlau; Moldåan Regional Stage (early Katian Stage, Late Ordovician); Neben Coll.; illustrated in Fig. 25; MB.C.32326.</p><p>Description</p><p>Holotype MB.C.32326 is a conch of an adult individual with an adorally incomplete, uncoiled body chamber (Fig. 25). The maximum diameter of the conch is 70 mm, with the coiled part accounting for up to 55 mm. In the last 0.75 whorls, the conch is discoidal (CWI decreases from 0.36 to 0.31) and subevolute (UWI increases up to 0.39). The coiling rate (WER wh) decreases from 2.98 to 2.42. The whorl profile is weakly compressed (WWI between 0.78 and 0.86), very weakly imprinted dorsally or not imprinted (IZR close to zero or zero) and elliptic in shape. From the rear part of the body chamber, the profile is slightly flattened ventrally. The suture line has a low lateral lobe and an external saddle. The body chamber is preserved over 115 degrees and becomes uncoiled from the previous whorl after ~70 degrees, with no indication of proximity to the aperture. In the outer volution, the relative cameral length (RCL) is 0.14. The shell ornament consists of sharp, raised lirae or thin annuli, which are also visible on the internal mould. The ornament elements are evenly spaced, slightly imbricated, and have fine lirae or growth lines between them.</p><p>Remarks</p><p>Discoceras sovaki sp. nov. is distinguished from other species of the genus by its comparatively small, extremely discoidal, adaperturally uncoiled, and sharply ornamented conch.</p><p>The holotype of D. sovaki sp. nov. is most similar to the holotype of D. alienum sp. nov., but differs in its larger adult size (70 mm vs 50 mm) and in having a body chamber that is much more strongly uncoiled from the previous whorls. Additionally, D. sovaki has a lower coiling rate (WER wh = 2.42 vs 2.61 at a diameter of 55 mm), a less compressed whorl profile (WWI = 0.86 vs 0.77 at dm = 55 mm), and a coarser shell ornamentation (sharp lirae or thin annuli vs fine lirae).</p><p>The conch ratios of D. sovaki sp. nov. are also similar to those of the late Sandbian D. vasalemmense from Estonia. However, in late growth stages, the latter species exhibits a heart-shaped whorl profile (where the conch narrows ventrally) and an even coarser ornamentation with strongly crenulated and irregularly spaced transverse elements (Kröger &amp; Aubrechtová 2018).</p><p>Geographic and stratigraphic occurrence</p><p>Northern Germany; early Katian Stage, Late Ordovician.</p></div>	https://treatment.plazi.org/id/03ED0C5EFFFCFFB0FDAB46057E04FA53	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFFDFFB6FDA442C07E04FE2F.text	03ED0C5EFFFDFFB6FDA442C07E04FE2F.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Discoceras alienum Aubrechtová & Korn & Kröger 2026	<div><p>Discoceras alienum sp. nov.</p><p>urn:lsid:zoobank.org:act: 6E931B16-8922-43E2-9558-DD1F36CE8A40</p><p>Figs 23, 26; Table 15</p><p>Diagnosis</p><p>Species of the genus Discoceras with adult conch size of 55 mm; adapertural half of the body chamber slightly uncoiled; whorl profile in external volution weakly compressed (WWI = 0.77), barely imprinted dorsally (IZR close to zero or zero), and elliptic in shape; aperture extended with a ventral sinus; shell ornament of raised lirae, slightly unevenly spaced, slightly imbricated with fine lirae or growth lines in between.</p><p>Etymology</p><p>From the Latin ‘alienum’ (adj., neut.) = ‘foreign’, referring to the origin of the holotype from erratic boulders.</p><p>Type material</p><p>Holotype GERMANY – Brandenburg • Oderberg; Moldåan Regional Stage (early Katian Stage, Late Ordovician); Neben Coll.; illustrated in Fig. 26; MB.C.32327.</p><p>Description</p><p>Holotype MB.C.32327 is an adult conch, 55 mm in diameter, with a partly uncoiled body chamber (Fig. 26). The conch is discoidal (CWI = 0.29) and subevolute (UWI = 0.38). In the last 90 degrees of the conch, the coiling rate (WER wh) decreases from 2.81 to 2.61, and the whorl profile becomes less compressed (WWI increases from 0.68 to 0.77); it is elliptic in shape. The whorls are weakly imprinted dorsally or not imprinted (IZR close to zero). The body chamber is preserved over 148 degrees, with its adapertural half uncoiled from the preceding whorl; the aperture extends into a small ventral sinus. The relative cameral length (RCL) in the last half whorl is 0.20. The shell surface has raised lirae (also visible on the internal mould), which are slightly unevenly spaced and slightly imbricated; fine lirae or growth lines are present between the coarser elements.</p><p>Remarks</p><p>Discoceras alienum sp. nov. differs from other species of the genus by its comparatively small, adaperturally only weakly uncoiled, and extremely discoidal conch with a compressed, elliptic whorl profile.</p><p>Discoceras alienum sp. nov. closely resembles D. sovaki sp. nov., but the former is smaller (55 mm vs 70 mm) and has a less strongly uncoiled body chamber. Additionally, D. alienum has a higher expansion rate (WER wh = 2.61 vs 2.42 at dm = 55 mm), a more compressed whorl profile (WWI = 0.77 vs 0.86 at dm = 55 mm), and a finer shell ornamentation (raised lirae vs regularly spaced sharp lirae or thin annuli). Discoceras vasalemmense differs from D. alienum sp. nov. in having a heart-shaped whorl profile and a coarser shell ornamentation, which consists of strongly crenulated and irregularly spaced transverse elements (Kröger &amp; Aubrechtová 2018).</p><p>Geographic and stratigraphic occurrence</p><p>Northern Germany; early Katian Stage, Late Ordovician.</p></div>	https://treatment.plazi.org/id/03ED0C5EFFFDFFB6FDA442C07E04FE2F	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
03ED0C5EFFFBFFB5FDB5450D7E60F865.text	03ED0C5EFFFBFFB5FDB5450D7E60F865.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Discoceras polonicum Aubrechtová & Korn & Kröger 2026	<div><p>Discoceras polonicum sp. nov.</p><p>urn:lsid:zoobank.org:act: ADC2FF6A-2F7C-48AD-9147-99C6A6D76B02</p><p>Figs 23, 27; Table 16</p><p>Diagnosis</p><p>Species of the genus Discoceras with adult conch diameter of ~ 100 mm where the last 50 degrees are uncoiled (diameter of coiled part ~ 70 mm); conch extremely discoidal (CWI ~ 0.30) and evolute (UWI up to 0.45); whorls not imprinted dorsally (IZR close to zero); whorl profile in the last whorl elliptic and weakly compressed (WWI ~0.90); whorl expansion rate decreases to WER ~ 2.20); shell ornament of imbricated lirae and evenly distributed thin ribs.</p><p>Etymology</p><p>From the Latin ‘polonicum’ (adj., neut.) = ‘polish’, referring to the origin of the holotype.</p><p>Type material</p><p>Holotype POLAND – West Pomerania • Ustronie Morskie; Moldåan Regional Stage (early Katian Stage, Late Ordovician); Müldner Coll.; illustrated in Fig. 27; MB.C.11992.</p><p>Description</p><p>Holotype MB.C.11992 is a plaster cast of a nearly complete conch in the adult growth stage. The conch has a maximum diameter of 100 mm and consists of 3.25 volutions (Fig. 27). The last 50 degrees of the external volution are widely uncoiled (diameter of the coiled part is 73 mm). In the last 0.75 whorl, the conch is extremely discoidal (CWI decreases from 0.32 to 0.29), more evolute (UWI increases from 0.41 to 0.45), and less expanded (WER decreases from 2.42 to 2.15). The whorl profile is weakly compressed (WWI around 0.90), elliptic, and barely imprinted dorsally (IZR close to zero). The shell ornament consists of imbricated lirae and evenly distributed thin ribs.</p><p>Remarks</p><p>The discoidal, compressed and adaperturally uncoiled conch of the holotype of Discoceras polonicum sp. nov. is similar to the holotypes of D. sovaki sp. nov. and D. alienum sp. nov. However, both D. sovaki and D. alienum are smaller in the adult stage (100 mm vs 70 mm and 55 mm, respectively), less compressed (WWI = 0.92 vs 0.86 and 0.77, respectively, at maximum conch diameter), and more expanded (WER wh = 2.15 vs 2.42 and 2.61, respectively, at maximum conch diameter). Additionally, D. alienum has a finer shell ornamentation than D. polonicum, and the body chamber does not uncoil as strongly in the former.</p><p>The holotype of D. polonicum sp. nov. (MB.C.11992) is also somewhat similar to the holotype of D. brandenburgense sp. nov. (MB.C.32324). The similarities include umbilical width, conch width, expansion rate, and the wide uncoiling of the last volution. However, the whorl profile in MB.C.32324 is not compressed but equidimensional or weakly depressed (WWI = 1.03–1.09), and the last 90 degrees of the conch expand much less rapidly (WER = 2.04–1.97 vs 2.27– 2.15 in D. polonicum).</p><p>Geographic and stratigraphic occurrence</p><p>Northern Poland; early Katian Stage, Late Ordovician.</p></div>	https://treatment.plazi.org/id/03ED0C5EFFFBFFB5FDB5450D7E60F865	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aubrechtová, Martina;Korn, Dieter;Kröger, Björn	Aubrechtová, Martina, Korn, Dieter, Kröger, Björn (2026): The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe. European Journal of Taxonomy 1036: 1-54, DOI: 10.5852/ejt.2026.1036.3173, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3173/14109
