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New Devonian Gastropod Genera Important for Paleogeographic Reconstructions

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New Devonian Gastropod Genera Important for Paleogeographic Reconstructions Journal of the Czech Geological Society 44/3ñ4(1999) 293 New Devonian gastropod genera important for paleogeographic reconstructions NovÈ rody devonsk˝ch gastropod˘ d˘leûitÈ pro paleogeografickÈ rekonstrukce (Czech summary) This publication is dedicated to the memory of (11 text-figs) VladimÌr HavlÌËek (1922ñ1999) ROBERT B. BLODGETT1 ñ JIÿÕ FR›DA2 1Department of Zoology, Oregon State University, Corvallis, Oregon, USA, [email protected] 2Czech Geological Survey, Kl·rov 3, 118 21 Praha 1, Czech Republic, [email protected] Twelve new Devonian gastropod genera are established in this paper which we deem important in better delineating Devonian biogeographic units. New genera include: Semilukispira, Teutonophon, Goldfussoceras, Manitobiella, Ibergia, Humboldtiella, Paragnesia, Winterbergiella, Spiniplatyceras, Roemeriella, Devononerita, and Dahmeria. In addition, one new Silurian genus, Ornatosinuitina, is established. Key words: Paleozoic, Gastropoda, Devonian, new taxa Introduction we hope to better communicate with fellow gastropodo- logists what these biogeographically-significant Devoni- On-going study by the two authors of Devonian gastro- an genera represent. In addition, we are also establishing pod biogeography has brought to our attention the need a new Silurian bellerophontid genus, Ornatosinuitina to establish many generic entities in order to better qua- gen. nov., from the Upper Silurian of Bolivia, which lify the taxonomic content of former biogeographic units came to our attention during study of Devonian species (realms, regions, and provinces). Previous works on De- of Sinuitina. vonian gastropod biogeography (Forney et al., 1981; Blodgett et al., 1988, 1990) have depended considerab- Systematic part ly upon usage of open nomenclatorial terminology (i. e. Subclass Amphigastropoda n. genus pleurotomarid 1, or spinose platyceratid plexus, Superfamily Bellerophontoidae MíCoy, 1851 etc.) and it is deemed necessary at this time to establish Family Sinuitidae Dall in Zittel, 1913 genera which are critical in better understanding Devo- Subfamily Bucanellinae Koken, 1925 nian biogeography. Despite intensive study of Devonian gastropods during the 19th Century, the general neglect Genus Ornatosinuitina gen. nov. received by this group during the early half of the 20th Text-fig. 1AñB Century, has resulted in a vast gap of detailed generic descriptions. Most notably lacking are updated revisions Type species: Sinuitina reyesi Fischer, 1969, from the Upper Si- lurian of Bolivia. of Upper Devonian faunas, i. e. the famous Iberger Kalk Etymology: Combination of the word ornatus (Latin for ìbearing of Germany, where a large percentage of Frasnian gast- ornamentî) and the genus name of Sinuitina. ropod species have been described to date. To date, only two genera are based upon Iberger Kalk species: 1. Ser- Diagnosis: Small helmet-shaped shell similar to Si- pulospira Cossmann, 1916, based on Serpulospira cent- nuitina and Branzovodiscus; dorsum bearing V-shaped rifuga F. A. Roemer, 1843; and 2. Coloniacirrus Bandel, sinus; whorl surface ornamented with transverse, poste- 1993, based on Ammonites primordialis Schlotheim, riorly curved threads crossed by spiral threads forming 1820. As noted by Linsley (1979, p. 252), our knowledge a reticulate pattern; circumbilical whorl area ornamen- of Upper Devonian gastropods is one of ìwoefull igno- ted only by radial threads. ranceî. In this paper, we establish several new genera Comparison: The new genus Ornatosinuitina resem- based on Iberger Kalk species, most of which were il- bles species of Sinuitina Knight, 1945 and Branzovodis- lustrated by drawings of rather poor quality, which do not cus Fr˝da, 1999, in its general shell shape. It differs from adequately reflect their shell characters. This reef asso- all of the three previously recognized subgenera of Si- ciated gastropod fauna is the most diverse known in the nuitina, S. (Sinuitina) Knight, 1945, S. (Vorticina) Gor- Frasnian, and share some affinity to the Koltuban Limes- don and Yochelson, 1987, and Sinuitina (Globosinuitina) tone fauna of the Urals (Nalivkin 1947, 1951). We are Fr˝da, 1998, in bearing a reticulate shell ornament. Gor- presently preparing a revision of the complete gastropod don and Yochelson (1987) proposed to divide Carboni- fauna of the Iberger Kalk. ferous species of Sinuitina into two subgenera. According In this short paper, we intend to establish genera which to these authors, the subgenus Sinuitina (Sinuitina) in- we feel have long needed naming. It is with this aim that cludes species with a broadly helmet-shaped whorl pro- 294 Journal of the Czech Geological Society 44/3ñ4(1999) condary shell deposit. The shape of whorl in radial se- ction is rhomboidal in Ornatosinuitina, but subtriangu- lar in Branzovodiscus. Composition: Only the type species is known. Family Bellerophontidae MíCoy, 1851 Subfamily Bellerophontinae MíCoy, 1851 Genus Semilukispira gen. nov. Type species: Bellerophon petinensis Nalivkin, 1930. A B Etymology: The genus name refers to the Semiluki beds from which the only illustrated specimen (the lectotype) was recovered. Fig. 1. AñB. Ornatosinuitina reyesi (Fischer, 1969), from the Upper Silurian of Bolivia. A ñ apertural view, B ñ lateral view, x7. (ex Fis- Diagnosis: Bellerophonitid gastropods with large, cher 1969, fig. 1). sharp, oblique ribs which are arched backwards from dorsum. Comparison: This genus is easily distinguished from file, which have a prominent somewhat flattened medi- all other related bellerophontid genera (i. e. Bellerophon, an crest bearing a pseudoselenizone and having promi- Aglaoglypta) by its sharp, oblique backwards inclined nent collabral ornament. Members of their new subge- ribs. No other bellerophontid genus bears such a distinc- nus Sinuitina (Vorticina) were diagnosed as species of tive ornament. Sinuitina having a whorl profile with the shape of a poin- Comments: According to Nalivkin (1941, p. 228), the ted arch and having collabral ornament which is promi- ornament consists of large tubercles which form more or nent on the inner flanks, and reduced on the outer flanks less regular rows, that form a sharp angle with the keel. and dorsum (Gordon ñ Yochelson 1987). The Early De- Commonly, these tubercles unite to form discontinuous vonian Sinuitina (Globosinuitina) differs from the latter low ribs (translation by authors). However, the photogra- subgenera in having a rounded dorsum without a medi- phs provided in both of the above papers of Nalivkin an crest and in having a deeper and wider dorsal sinus. show strong, backwards arched ribs which appear to be In addition, the shell ornament of Sinuitina (Globosinu- continuous in the single illustrated specimen (the lecto- itina) consists of distinct, widely spaced ribs extending type). The presence of tubercles referred to by Nalivkin across the entire whorl surface, however, the ribs are ir- on some parts of the shell (not visible in his photogra- regular in the middle of dorsum and form a ripple-like phs) suggest that the genus is allied to Aglaoglypta, pattern. The Silurian age Ornatosinuitina gen. nov. be- which is almost wholly restricted to the Frasnian. Howe- ars a reticulate shell ornament and is easily distiguished ver, the latter genus has an ornament of tubercles which by this character from all of the three previously reco- do not unite to form ribs. gnized subgenera of Sinuitina. No other species of Si- Composition: Only the type species, Bellerophon nuitina have such a pattern. The reticulate ornament of petinensis Nalivkin, 1930, from the Frasnian of the Rus- the Late Silurian type species of Ornatosinuitina so- sian Platform is known. mewhat resembles that of the Early Devonian Branzovo- discus Fr˝da, 1999. The type species of the latter genus, Genus Teutonophon gen. nov. Branzovodiscus bajae Fr˝da, 1999, differs from Orna- tosinuitina reyesi by the shape of the dorsum and a dif- Type species: Bellerophon striatus de Ferussac and Orbigny in Archiac and Verneuil, 1842, p. 353, plate 28, fig. 6. fering style of reticulate ornament. The shell of Ornato- Etymology: The name is derived from the term Teuton (Latin for sinuitina reyesi has a rounded dorsum in contrast to Bran- Germany) and the Greek word phone (sound or voice). zovodiscus bajae, which has an angular, helmet-shaped dorsum. The circumbilical area in Branzovodiscus is co- Diagnosis: Bellerophontid with a very large, globu- vered by a coinductural layer ornamented with fan-like, lar, narrowly phaneromphalous shell; in adult whorls the posteriorly curved lamellae (Fr˝da 1999, figs 1bñf). On outer surface of the thick shell ornamented by numerous the other hand, the ornament of the circumbilical area in coarse, undulose collabral ridges, which give the exteri- Ornatosinuitina gen. nov. consists of fine radial threads or a distinctive ìshingledî appearance. (see Fischer 1969 and herein fig. 1). In addition, the re- Comparison: This new genus is very similar to the ticulate ornament in the latter genus is formed by the in- genus Bellerophon Montfort, 1808, in its general shell tersection of collabral and spiral threads, in contrast to shape. Knight et al. (1960) divided the genus Bellerophon Branzovodiscus bajae, whose shell lacks spiral elements. into three subgenera Bellerophon (Bellerophon) Montfort, The reticulate ornament of Branzovodiscus bajae is li- 1808, Bellerophon (Aglaoglypta) Knight, 1942, and Bel- mited only to an area about half of whorl back from the lerophon (Pharkidonotus) Girty, 1912, according to the aperture
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