62 BIVALVE MOLLUSKS FROM MAXVILLE LIMESTONE VOL. 107 OHIO JOURNAL OF SCIENCE R. D. HOARE 63 Bivalve Mollusks from the Maxville Limestone (Mississippian) in Ohio Richard D. Hoare 1, Department of Geology, Bowling Green State University, Bowling Green, OH 43403 A. Bivalve mollusks are a common component of the Chesterian Maxville Limestone in Ohio, although not as abundant as the brachiopods. A number of taxa were found preserved as internal molds making identi cation di cult. e new species Leptodesma (Leptodesma) rhysema, Limipecten lamellus, Astartella clinata, and Sanquinolites hekitoensis are among the 29 taxa now known from the formation. e shale unit near the top of the formation contains mytilaceans and abundant pectenaceans dominated by Aviculopecten winchelli Meek, 1875, the latter with inarticulate brachiopod epibionts. OHIO J SCI 107 (4): 63-75, 2007 INTRODUCTION missouriensis Swallow, 1863; Schizodus chesterensis Meek and Collections from eight localities have produced a signi cant Worthen, 1860 = Schizodus sp.;Allorisma andrewsi Whit eld = increase in the known bivalve fauna of the Mississippian Wilkingia andrewsi (Whit eld, 1882); and Allorisma maxvillensis (Chesterian) Maxville Limestone (Fig. 1). Previous work by Whit eld = Wilkingia maxvillensis (Whit eld, 1882). To this Whit eld (1882, 1891, 1893), Morse (1911) and Hoare and list Morse (1911) added one species: Cypricardella oblonga Hall, others (1988) described seven taxa. An additional 22 taxa are 1858a = Edon oblonga (Hall, 1858a). A short note by Hoare and included herein. Corrections of previous taxonomic assignments others (1988) added two species in describing color patterns on are given in the discussion on previous work and in the systematic Aviculopecten winchelli Meek, 1875, and Streblopteria sp. from the section. e location of Whit eld’s bivalve specimens is unknown, shale near the top of the Maxville. presumably lost. Six specimens collected by Morse are in the Hyde (1953) described numerous Mississippian bivalves from collections of the Orton Geological Museum, e Ohio State Ohio but did not include the Maxvillle Limestone. University. e purpose of this study is to describe and illustrate the known bivalve fauna and to update the taxonomic assignment EPIFAUNA of previously described taxa. e lack of shell material on most bivalve specimens precludes the preservation of any epibionts that may have been attached. e MATERIALS AND METHODS brachiopods in the Maxville Limestone have a common and varied Collections from the limestone and shale were obtained by the epibiont fauna present on the shells (Hoare, 2003). It is likely that use of hammer and sledge in the eld as well as nding weathered specimens of bivalves also had attached epibionts. out specimens. Further preparation was done under a microscope In several instances pedicle valves of Orbiculoidea cf. O. keokuk using a vibratool and ne needles. In extracting specimens from (Gurley, 1884) were found preserved on the valves of Aviculopecten the limestone the shell commonly adhered to the matrix and in winchelli Meek, 1875, in the upper black shale unit (Fig. 2.1-2.3) It chipping the matrix away from specimens the shell usually broke is possible that the larvae of these inarticulate brachiopods suvived up as it was exposed. Samples of weathered limestone were boiled by becoming attached to the rm substrate of the bivalve shell. A in a solution of water and Quaternary O which liberated numerous brachial valve of Oehlertella pleurites (Meek, 1875) was also found small specimens, mainly preserved as internal molds. Many of these in the shale but not on a bivalve shell (Fig. 2.4). Several small were not well enough preserved to allow speci c identi cation. fragments of brachial valves were also found in the shale. Specimens from the shale unit were all disarticulated valves. Shell material was preserved, although very thin and incomplete. ese RESULTS specimens were coated with a thin layer of Styrofoam dissolved in e bivalve fauna of the Maxville Limestone is much more benzene to preserve the shell material and to protect the impression diverse than previously known. An additional 22 taxa are described of the shell in the shale matrix. herein including: All specimens were coated with a thin layer of magnesium Nuculopsis a . N. shumardana (Hall, 1858a) oxide for photographic purposes to enhance the ornamentation. Nuculopsis sp. Photography was done with a Leica camera. Polidevcia cf. P. stevensiana (Girty, 1910) Collections made by the late M. T. Sturgeon and students, Palaeoneilo sp. Ohio University, and the late A. S. Horowitz, Indiana University, Phestia cf. P. pandoraeformis (Stevens, 1858) were given to the author to supplement the collections at Bowling ?Solemya (Jania) sp. Green State University. Modiolus (Modiolus) fountainence Weller, 1916 M. (M.) waverliensis (Herrick, 1888) PREVIOUS WORK ?ambonychiid gen. and sp. e four species of bivalves described by Whit eld (1882, 1891, Myalinella sp. 1893) include: Pinna maxvillensis Whit eld = Pinna (Sulcatopinna) Leptodesma (Leptodesma) rhysema n. sp. L. (L.) cf. L. (L.) matheri Elias, 1957 Aviculopecten sp. A 1 Corresponding author: Richard D. Hoare, Professor Emeritus, Department of Aviculopecten sp. B Geology, Bowling Green State University, Bowling Green, OH 43402. Email: [email protected] Limipecten lamellus n. sp. 64 BIVALVE MOLLUSKS FROM MAXVILLE LIMESTONE VOL. 107 OHIO JOURNAL OF SCIENCE R. D. HOARE 65 Limipecten sp. in the repository of the Orton Geological Museum, e Ohio State are not preserved. ey di er from N. rectangular (McChesney, Description Streblochondria sp. University (OSU). 1860) by being more attenuate posteriorly and from N. okawensis Small internal molds; beaks tightly incurved, anterior to Schizodus cf. S. chesterensis Meek and Worthen, 1860 Genus Nuculopsis Girty, 1911 Schenk, 1939 by being more elongate. e better preserved midlength; strongly sloping posterodorsal margin; ventral margin Astartella clinata n. sp. Nuculopsis a . N. shumardana (Hall, 1858a) specimens range in size from 7.6 mm long, 5.1 mm high, 4.1 mm convex becoming concave posteriorly; anterior margin broadly Edmondia sp. (Fig. 3.1-3.4) wide to 4.8 mm long, 3.7 mm high, 2.0 mm wide. convex; internal features not observed. Specimens range in size Sanguinolites hekitoensis n. sp. from 4.3 mm long, 2.8 mm high, 2.0 mm wide to 2.0 mm long, ?Sedgwickia sp.. Nucula shumardana Hall, 1858a, p. 16; Whit eld, 1882, Material 2.0 mm high, 1.4 mm wide. Two species of inarticulate brachiopods were found in the black p. 57, pl. 7, gs. 2-6; Hall, 1883, p. 343, pl. 30, gs. 2-6; Four internal molds including OSU 52354-52356 from Discussion shale unit, Orbiculoidea cf. O. keokuk (Gurley, 1884) and Oehlertella Beede, 1906, p. 1323, pl. 23, gs. 2-6. localities 1, 2. All of the specimens found are small internal molds and pleurites (Meek, 1875). ese were presumably epibionts associated Genus Polidevcia Chernyshew, 1951 appear to be juveniles. ey appear to be most similar to P. with pectenaceans. Further collecting will likely increase the number Description Polidevcia cf. P. stevensiana (Girty, 1910) pandoraeformis. Phestia nasata (Hall, 1858) is somewhat similar of bivalve taxa known in the Maxville Limestone. Subtrigonal shell with beaks near anterior end; beaks prosogyrate (Fig. 3.10-3.14) but the beaks are located further posteriorly and the shell is less extending above hingeline; hingeline slopes steeply to narrowly attenuate posteriorly. SYSTEMATIC PALEONTOLOGY curved posterior margin; anterior margin truncate; surface with Leda stevensiana Girty, 1910, p. 226. e supergeneric classi cation of Newell (1969, p. N205) is numerous closely-spaced, comarginal ridges; internal features not Phestia stevensiana (Girty). Pojeta, 1969, p. 19, pl. 3, gs. 24- Material followed and not reproduced herein. Specimens have been placed observed. Specimens range from 4.3 mm long, 3.8 mm high, 1.5 29. Sixteen specimens including OSU 52363 from localities 1, 2. mm wide to 1.8 mm long, 1.4 mm high, 1.1 mm wide. Polidevcia stevensiana (Girty). Hoare, 1993, p. 378, g. 2.17- Genus Solemya Lamarck, 1818 Discussion 2.21. Subgenus Jania King, 1850 One of the specimens has the shell preserved (Fig. 3.3), the rest Description Solemya (Jania) sp. are internal molds that are distorted to varying degrees. Nucula Elongate, narrow, with nuculaniform shape; beaks anterior of (Fig. 3.20) shumardana was described from the Salem Limestone in Indiana. midlength, low, incurved, prosogyrate; ornament and internal Discussion e specimens from the Maxville Limestone di er from those in features not observed. Specimens range in size from 5.3 mm A single partial shell of a le valve shows characteristics the Salem Limestone by being thicker and less truncate anteriorly long, 2.8 mm high, 1.9 mm wide to 2.0 mm long, 1.1 mm high, distinguishing it from known Mississippian bivalves. e specimen with the beaks not located as far anteriorly. Otherwise they closely 1.0 mm wide. was apparently elongate with a straight hingeline, with prosogyrate resemble Hall’s species. Discussion beaks close to the anterior extremity. e umbonal area is smooth Most of the specimens are small juveniles preserved as distorted but the ventral and posterior portions of the valve bear relatively Material internal molds. coarse, closely-spaced costae radiating from the direction of the Forty-nine specimens including OSU 52351-52353 from beak. One major comarginal growth line is present. e shell is localities 2, 8. Material partially distorted. Exact measurements cannot be made but the Nuculopsis sp. Over 100 specimens including OSU 52357-52359 from specimen is 12.6 mm long, 9.0 mm high, and 2.9 mm wide. It (Fig. 3.5-3.9) localities 1, 2. looks somewhat similar to S. (J.) primaeva Phillips, 1836, from the Discussion Genus Palaeoneilo Hall and Whit eld, 1869 Carboniferous of England, although the costae are coarser and do Several small internal molds have the basic shape of Nuculopsis.