Joseph G. Carter, Cristian R. Altaba, David C. Campbell, Peter J. Harries, and Peter Skelton
The following classification summarizes the suprageneric taxonomy of the Bivalvia for the upcoming revision of the Bivalvia volumes of the Treatise on Invertebrate Paleontology, Part N. The development of this classification began with Carter (1990a), Campbell, Hoekstra, and Carter (1995, 1998), Campbell (2000, 2003), and Carter, Campbell, and Campbell (2000, 2006), who, with assistance from the United States National Science Foundation, conducted large-scale morphological phylogenetic analyses of mostly Paleozoic bivalves, as well as molecular phylogenetic analyses of living bivalves. During the past several years, their initial phylogenetic framework has been revised and greatly expanded through collaboration with many students of bivalve biology and paleontology, many of whom are coauthors. During this process, all available sources of phylogenetic information, including molecular, anatomical, shell morphological, shell microstructural, bio- and paleobiogeographic as well as stratigraphic, have been integrated into the classification. The more recent sources of phylogenetic information include, but are not limited to, Carter (1990a), Malchus (1990), J. Schneider (1995, 1998a, 1998b, 2002), T. Waller (1998), Hautmann (1999, 2001a, 2001b), Giribet and Wheeler (2002), Giribet and Distel (2003), Dreyer, Steiner, and Harper (2003), Matsumoto (2003), Harper, Dreyer, and Steiner (2006), Kappner and Bieler (2006), Mikkelsen and others (2006), Neulinger and others (2006), Taylor and Glover (2006), Kříž (2007), B. Morton (2007), Taylor, Williams, and Glover (2007), Taylor and others (2007), Giribet (2008), and Kirkendale (2009). This work has also benefited from the nomenclator of bivalve families by Bouchet and Rocroi (2010) and its accompanying classification by Bieler, Carter, and Coan (2010).
This classification strives to indicate the most likely phylogenetic position for each taxon. Uncertainty is indicated by a question mark before the name of the taxon. Many of the higher taxa continue to undergo major taxonomic revision. This is especially true for the superfamilies Sphaerioidea and Veneroidea, and the orders Pectinida and Unionida. Because of this state of flux, some parts of the classification represent a compromise between opposing points of view. Placement of the Trigonioidoidea is especially problematic. This Mesozoic superfamily has traditionally been placed in the order Unionida, as a possible derivative of the superfamily Unionoidea (see Cox, 1952; Sha, 1992, 1993; Gu, 1998; Guo, 1998; Bieler, Carter, & Coan, 2010). However, Chen Jin-hua (2009) summarized evidence that Trigonioidoidea was derived instead from the superfamily Trigonioidea. Arguments for these alternatives appear equally strong, so we presently list the Trigonioidoidea, with question, under both the Trigoniida and Unionida, with the contents of the superfamily indicated under the Trigoniida.
Typified Versus Descriptive Names
The present classification gives preference to typified names over descriptive names above the family-group, following the recommendation by Stys and Kerzhner (1975) and Starobogatov (1991). Typified names are more useful than descriptive names, because their root indicates taxonomic affiliation and their suffix can be modified to reflect taxonomic rank. Descriptive names can be advantageous for indicating a key morphological feature, but this feature may not characterize all members of the group (e.g., the Palaeotaxodonta), and descriptive names indicate nothing about the phylogenetic placement of the taxon.
We agree with Dubois (2005) that adoption of a descriptive name should be guided by the spirit of priority and adherence to original definition. The term original definition is presently interpreted in a phylogenetic sense to mean the monophyletic clade defined by the original members of the taxon, their common ancestor, and all of its descendants. We have, therefore, not formally adopted the terms Palaeoheterodonta and Heterodonta, the original definitions of which have no useful phylogenetic equivalent in the present classification. These descriptive names, as well as the phylogenetically more useful Euheterodonta and Nepiomorphia, are, however, placed in the classification in bold-face type after their synonymous, or approximately synonymous, typified name. The descriptive names Autobranchia, Protobranchia, Pteriomorphia, and Heteroconchia are presently formally adopted. Grobbens (1894) Autolamellibranchiata is herein replaced with the shorter, more euphonic Autobranchia, following C. M. Kolesnikov (1977), T. Waller (1978), Naumov (2006), and Bieler, Carter, and Goan (2010).
Authorship and Priority of Nomina above the Family-Group
The ICZN (1999) Code does not regulate taxon names above the family-group. Previous workers have used various guidelines to determine the composition, authorship, and priority of such names. Some have based these names on the oldest valid and available included familygroup name in the group, or the first publication to define the group in a modern sense, or the oldest valid and available typified name above the family-group. We have adopted the latter guideline, with separate authorship and priority for names above and within the family-group. For example, the hyporder name Antipleuroidei Kříž, 2007, is presently adopted, even though it contains the superfamily Dualinoidea Conrath, 1887, because order Antipleuroida Kříž, 2007 is the oldest valid and available typified name above the family-group for this clade. Similarly, Hippuritida Newell, 1965, is adopted for an order that includes some families established as early as 1847 and 1848. In cases where a new name above the family-group is needed, but an appropriate typified root name above the family-group is not available, the earliest valid and available typified name in the family-group is used as the root, but with a new publication date. Separate priority for names above and within the family-group is preferred because it allows for the retention of a number of widely used but otherwise lesser priority names above the family-group, such as order Hippuritida.
Typified names above the family-group, which are based on a junior generic synonym or homonym, are presently regarded as unavailable and are disregarded for purposes of priority. This is a departure from the ICZN (1999) Code rules for family-group names. For example, Anatina Lamarck, 1818, is a junior homonym of Anatina Schumacher, 1817. Consequently, the suborder Anatinacea P. Fischer, 1887, based on Anatina Lamarck, 1818, is not available and has no bearing on the priority of any other typified name above the family-group. Also, the suborder Saxicavoidea Morretes, 1949, is unavailable because it is based on Saxicava Fleuriau de Bellevue, 1802, a junior synonym of Hiatella Bose ex Daudin MS, 1801, and the suborder Saxicavoidea has no bearing on the priority of the presently adopted order Hiatellida. However, typified names above the family-group are not presently regarded as unavailable on the basis that their nominal family-group name is a junior synonym of another family-group name. For example, the suborder Leptonidina Dall, 1889, is available despite the fact that its nominal familygroup name, Leptonidae J. Gray, 1847b, is now a junior synonym of Lasaeidae J. Gray, 1842.
Priority is presently given to the higher ranking of two or more simultaneously published typified or descriptive names above the family-group. This is an extension of Article 24.1 of the ICZN (1999) Code for family-group names. For example, order Pectinacea J. Gray, 1854a, has priority over the simultaneously established (unspecified rank above family-group but below suborder) Anomiaina J. Gray, 1854a. Changes in the rank, spelling, and/or taxonomic composition of a descriptive name are not presently considered to be a valid basis for changing the author and date of the descriptive name.
Paraphyletic and polyphyletic taxa. Paraphyletic higher taxa are unavoidable in a classification that includes ancestors and descendants. This is illustrated by J. Schneiders (1995, 1998a, 1998b, 2002) revision of the superfamily Cardioidea. Schneider reduced superfamily Tridacnoidea to subfamily Tridacninae within Cardiidae to elimininate paraphyly of Cardioidea with respect to Tridacnoidea. However, this reduction in rank merely shifted paraphyly from Cardioidea to its subfamily Cerastodermatinae, the ancestral stock group for Tridacninae. Building a taxonomy that includes living and extinct taxa presents a dilemma: choosing between explicitly recognizing paraphyletic taxa or multiplying supraspecific taxa beyond reasonable bounds (Cela-Conde & Altaba, 2002; Altaba, 2009). We favor an evolutionary classification that, being based upon cladistic analysis, does not dismiss evidence and reflects ancestor-descendant relationships. Paraphyletic taxa are indicated in the classification by an exclamation point (!) after the name.
Polyphyletic taxa are avoided in the classification, except in rare instances where the polyphyly is limited to descendants of the same genus, originating at about the same time. For example, the subfamily Lymnocardiinae is believed to contain more than one tribe derived, in the Miocene, from Cerastoderma of the subfamily Cerastodermatinae. In this case, Lymnocardiinae is also paraphyletic because it does not include Cerastoderma, the common ancestor of all its members.
Linnean Ranks and Suffixes for Names above the Family-Group
The present classification utilizes an increased number of Linnean ranks to adequately portray phylogenetic relationships. The number of Linnean ranks reflects a substantial increase in suprageneric taxa described over the past 50 years, and the fact that morphological and molecular phylogenetics have made possible a detailed phylogenetic framework for the Bivalvia. In order to minimize the number of Linnean ranks, we have not ranked the clade Eubivalvia and certain clades in more intensively studied groups, such as the Pectinoidea, Radiolitoidea, and Cardioidea. Those preferring a simpler classification can achieve this by disregarding some of the less familiar ranks, such as subcohort, infrasubcohort, megaorder, hyporder, minorder, epifamily, and series. Such condensation of the classification will hide some phylogenetic relationships, but it might be better suited for some summary and discussion purposes. The present Linnean synopsis does not show ancestor-descendant relationships, but these are identified in the phylogenetic classification under preparation for the revised Bivalvia Treatise.
There is currently no consensus on suffixes for typified names above the family-group. The proposal by Rohdendorf (1977) for general zoology is compared in Table 1 with the classifications of the Bivalvia by Cox and others (1969, 1971), Starobogatov (1984, 1992), Waterhouse (2008), and that used herein.
The suffix -ia is commonly used for bivalve subclasses and infraclasses, e.g., Protobranchia, Autobranchia, Pteriomorphia, and Heteroconchia (T. Waller, 1978; Ander, 1999). The suffix -ata was used by Blainville (1825, 1827) and by Grobben (1894) for orders (Lamellibranchiata and Autolamellibranchiata, respectively), and by Grobben (1892), Keen (1963), and Pojeta (1978) for subclasses (Protobranchiata, Anomalodesmata, and Lucinata, respectively).
Cohort and subcohort are generally inserted between class-group and ordinal-group names, although cohort has been used below the ordinal level for dinosaurs (e.g., Benton, 2005). The ranks subcohort, megaorder, hyporder, minorder, epifamily, and series have not been used before for the Bivalvia. Megaorder, hyporder, and minorder have been used for tetrapods, although at varying ranks in the case of hyporder and minorder (cf. Novacek, 1986; Sereno, 1986, 1999; E. Gaffney & Meylan, 1988; van Valen, 1994; McKenna & Bell, 1997; Benton, 2005).
Waterhouse (2000, 2001, 2008) suggested using -idina for suborders rather than the -ina of some earlier authors, because -ina is reserved for sub tribes by Article 29.2 of the ICZN (1999) Code. The subordinal suffix -oidina, advocated by Waller in T. Waller and Stanley (2005, p. 8), is presently rejected because -idina is more consistent with the -ida ordinal ending adopted by Scarlato and Starobogatov (1969, 1979a), Waterhouse (2008), and Bieler, Carter, and Coan (2010). The suffix -oid, as in nuculoid and pterioid, is retained for informal reference to orders, to avoid confusion with informal references to families, such as nuculids and pteriids.
The rank epifamily, with the suffix -oidae, has been used between superfamily and family for reptiles (Bour & Dubois, 1984; de la Fuente, 2003; van der Meijdin & others, 2005) and for insects (M. Engel, 2005). The term series has been used between superfamily and family for Lepidoptera.
The present classification of the Bivalvia differs from previous ones in its uniform priority basis for determining names above the family-group, more consistent use of typified rather than descriptive names above the family-group, and labelling of paraphyletic taxa. Details of the classification format are described below.
The nominotypical family, subfamily, or tribe is listed first within each superfamily, family, or subfamily, respectively. This is followed by the remaining members of the group in alphabetical order. At higher taxonomic ranks, simpler clades are generally listed before more complex clades.
Suffixes for taxonomic ranks.
Paraphyletic taxa are indicated by an exclamation point after the name, e.g., Grade Euprotobranchia!.
Extinct taxa are indicated by the symbol • before the name, e.g., •Family Actinodontidae.
Taxonomically Isolated Plesions and Paraphyletic Taxa
Some plesions and some paraphyletic taxa are taxonomically isolated in the sense that they lack membership in one or more expected, immediately higher Linnean ranks, e.g., the family Palaeocarditidae placed within the suborder Cardiidina without an intervening hyporder, minorder, or superfamily. Such isolated plesions and paraphyletic taxa are presently labelled plesions and paraplesions, respectively, to emphasize their deviation from the normal Linnean hierarchy.
Taxon Dates and References
Where two references are given for a taxon, e.g., Glycymerididae Dall, 1908 (Leach in J. Gray, 1847a), the second one indicates the source of date priority. See Bouchet and Rocroi (2010) for documentation.
Informal Descriptive Names
Commonly used descriptive names that are not presently formally adopted but have exact phylogenetic equivalents in the present classification are placed in bold face type after their correlative typified name, e.g., Eupteriomorphia, Foliobranchia, Euheterodonta, Neoheterodontei, Nepiomorphia, Palaeotaxodonta. Commonly used descriptive names that are not presently formally adopted and have no exact phylogenetic equivalent in the present classification (as determined by their original composition) are placed in bold-face type and italics after their most compatible typified name, e.g., Palaeoheterodonta, Heterodonta. The taxonomically widely dispersed taxa formerly assigned to the Anomalodesmata are indicated by underlining.
ABSTRACT OF CLASSIFICATION
To more clearly illustrate the major structure of the classification, the following abstract includes only the higher taxonomic ranks and their higher ranking paraplesions. A more detailed abstract, which includes all taxa at or above the rank of superfamily, plus all plesions and paraplesions, is provided in Appendix 3 (p. 27 herein). Symbols: • = extinct; ! = paraphyletic; underlining = former members of Anomalodesmata; ? = taxonomic placement uncertain.
We thank Michael Amler, Lyle Campbell, Jill Hardesty, and an anonymous reviewer for their critical reviews and/or editing of this manuscript. Thomas Waller provided helpful comments regarding the pectinoids. Richard Petit and Philippe Bouchet helped document several literature sources. We also thank John Taylor for pointing out that the putative cardiniid Tellidorella S. Berry, 1963, is a lucinid. This research was supported by NSF Grants GB-36048 and EAR-0003431, and University of North Carolina Research Council grants to J. G. Carter.
APPENDIX 1. NEW SUPRAGENERIC TAXA AND UNRANKED CLADE NAMES
Abbreviations: CL, simple crossed lamellar; CCL, complex crossed lamellar; ISP, irregular simple prismatic; RSP, regular simple prismatic.
Afghanodesmatida Carter, herein, ord. nov ., nom. transl. et correct. ex Afghanodesmatidae Scarlato & Starobogatov (1979a, p. 19, 25). Taxonomic content indicated above.
Anadontellidae Silantiev, herein, fam. nov. Type genus, Anadontella Betekhtina in Betekhtina, Starobogatov, & Jatsuk, 1987, p. 41. Family diagnosis; members of the superfamily Prokopievskioidea with relatively thin, elongate, subtriangular (Anthraconauta-like) or subrectangular, equivalve or slightly inequivalve shells, with an edentulous hinge, distinctly multilayered shells with fine, commarginal growth lines, and no radial microsculpture. Some forms (e.g., Synjaella) are strongly tapered posteroventrally and have a sinus-like concavity on the posterior and ventral margins. Ligament opisthodetic, possibly submerged, with single, narrow ligament groove appearing on internal molds, possibly representing secondarily simplified duplivincular ligament. Outer shell layer calci tic irregular simple prismatic or fibrous prismatic, middle and inner shell layers nacreous, except immediately internal to ISP palliai myostracum, where irregular CCL is developed. Nonmarine. Anadontellidae resembles Naiaditidae but differs from Prokopievskiidae in lacking radial microsculpture. At least Anadontella differs from some Prokopievskiidae and Naiaditidae in having a distinct sublayer of irregular CCL between the palliai myostracum and the nacreous inner part of the inner shell layer. Anadontellidae differs from Naiaditidae in having a single, narrow, opisthodetic ligament groove instead of an amphidetic, duplivincular ligament. This family also contains Soanellina Betekhtina, 1990, and Synjaella Kanev, 1993.
Antijaniridae Hautmann, herein, fam. nov. Type genus, Antijanira Bittner, 1901, p. 49. Family diagnosis; small shells with well-developed radial ribs occasionally bearing spines; ribs either equal in strength or intercalated in two or more ranks; discs circular to slightly retrocrescent, biconvex or with right disc flatter; dorsal margin straight and relatively short; beaks located close to midpoint of dorsal margin; byssal notch well developed; ctenolium not observed; ligament alivincular-areate, with centrally or slightly posteriorly located resilifer; shell with calcitic outer shell layer, regular simple prismatic in right valve and predominantly homogeneous in left valve, plus aragonitic crossed lamellar middle and inner shell layers. Comparisons; the ligament system indicates affinity with taxa presently classified with Aviculopectinoidea or Heteropectinoidea, contrary to Hertlein's (1969, p. 355) placement of the “Antijanira group” in Pectinidae. The style of ornamentation in Antijaniridae is not observed in other Triassic Aviculopectinoidea or Heteropectinoidea, except for Ornithopecten (Ornithopectinidae), which differs in having a broad right posterior wing and a delicate right anterior auricle. This family also contains Amphijanira Bittner, 1901, and Oxypteria Waagen, 1907. The affinity of Oxypteria to this group was first recognized by Allasinaz (1972, p. 266).
Arenigomyidae Carter, herein, fam. nov. Type genus, Arenigomya Cope, 1996, p. 1017. Cope (1996, p. 1017) gave the following diagnosis for Arenigomya, which is also the present family diagnosis; “Equivalve, edentulous, trapezoidal bivalve with length one-and-ahalf times greater than height. Surface with fine concentric undulose ornament, radial striae and anteriorly prominent commarginal rugae. Surface detail of finely granulose ornament. Strong carina runs from posterior side of umbo to postero-ventral margin of valves. Each valve with subumbonal articulation device.” This family is monogeneric.
Aulacomyini Carter, herein, tribe nov. Type genus, Aulacomya Mörch, 1853 in 1852–1853, p. 53. This new tribe is proposed because Perninae Scarlato & Starobogatov, 1979b, p. 24, is invalid; its type genus was given without author or date but is inferred from the context to be Perna Philipsson in Retzius, 1788. This Perninae is a junior homonym of Pernadae J. Fleming, 1828 (spelling corrected by Zittel, 1895, to Pernidae, the latter based on Perna Bruguière, 1789, in Bruguière, Lamarck, & Deshayes, 1789–1832, a junior synonym of Isognomon Lightfoot, 1786). Tribe Aulacomyini diagnosis: smooth or radially ribbed, mytiliform members of Mytilinae in which the anterior adductor muscle is present only in the juvenile stage. Other than the type genus, this tribe contains Ischadium JukesBrowne, 1905, Perna Philipsson in Retzius, 1788, and Choromytilus T. Soot-Ryen, 1952.
Colpomyida Carter, herein, ord. nov ., nom. transl. et correct. Carter, herein, ex Colpomyidae Pojeta & Gilbert-Tomlinson, 1977, p. 37. Taxonomic content indicated above.
Concinellinae Silantiev, herein, subfam. nov. Type genus, Concinella Betekhtina, 1966, p. 108, 198. Subfamily diagnosis: members of family Prokopievskiidae with thin, subcircular to subtriangular, inequivalve or equivalve, edentulous shells, probably an opisthodetic, possibly submerged ligament with a single, narrow ligament groove appearing on internal molds, possibly representing a secondarily simplified, duplivincular ligament. Ornamentation of regularly imbricated growth lines and fine radial striae. Outer shell layer calcitic irregular simple prismatic; middle and inner shell layers nacreous. Nonmarine. This subfamily is monogeneric.
Crassatellopsidae Carter, herein, fam. nov. Type genus, Crassatellopsis Beushausen, 1895, p. 146. The following family diagnosis is modified from the description of Crassatellopsis by P. A. Johnston (1993): two cardinal teeth in right valve, one anterior and one central, the latter bordered posteriorly by a narrow shelf; two cardinal teeth in left valve, left cardinal tooth immediately posterior to left pivotal cardinal is slender and directed posteroventrally; right cardinal tooth anterior to right pivotal cardinal tooth is slender and directed anteroventrally; no lateral teeth and no shell marginal teeth. Shell shape similar to Astarte, trigonally suboval or subcircular; umbos pointed, prosogyrate; shell margin broadly concave immediately anterior to umbos, convex elsewhere; lunule and escutcheon absent; exterior ornament of commarginal ribs, rugae, and growth lines; ribs generally prominent and regularly spaced in early growth stages, in some cases diminishing gradually throughout ontogeny. Hinge plate narrow or broad. Anterior adductor muscle scar reniform or moderately elongate; posterior adductor muscle scar larger. Anterior pedal retractor scar positioned above and separate from anterior adductor scar; above this scar 2 to possibly 4 subumbonal muscle scars are positioned at the junction of hinge plate and the shell interior, with the dorsalmost of these scars most prominent and usually positioned directly below the left or right principal cardinal tooth or its socket in the opposite valve. Posterior internal radial ridge present immediately anterior to posterior adductor muscle scar. Palliai line continuous, nonsinuate, relatively close to shell margin ventrally. Lamellar sublayer of ligament inserting into opisthodetic, narrow, submarginal fossette, but fibrous sublayer of ligament inserting within a strongly oblique, short resilifer; ligament sublayers separated by indistinct ridge on posterior margin of resilifer. This family is monogeneric.
Darininae Signorelli, herein, subfam. nov. Type genus, Darina J. Gray, 1853, p. 42. Subfamily diagnosis: members of Mactridae with thin, fragile, oval to subcircular, elongate, anteriorly and posteriorly gaping shells, nearly median umbos, a rudimentary, external ligament, a large resili um on a ventrally to posteroventrally strongly projecting chondrophore, a subdued posterior umbonal ridge, and hinge dentition that is concentrated on the central part of the hinge. This subfamily also contains Darcinia B. Clark & Durham, 1946. Darininae differs from Mactrinae in having a more elongate shell shape, thinner, more pellucid valves, and more medially concentrated hinge dentition. It differs from Kymatoxinae in having a more elongate, more nearly equilateral shell shape, anterior as well as posterior gapes, less prominent sculpture, and stronger anterior lateral teeth. It differs from Lutrariinae in having a more projecting chondrophore and more median umbos.
Entoliidina Hautmann, herein, subord. nov ., nom. transl. et correct. M. Hautmann, herein, ex Entoliinae Teppner, 1922, p. 89. A suborder proposed for the superfamilies Euchondrioidea and Entolioidea, as indicated above.
Eubivalvia Carter, herein, unranked clade nov. A descriptive clade name proposed for the subclasses Protobranchia and Autobranchia.
Eufistulaninae Carter, herein, subfam. nov. Type genus, Eufistulana Eames, 1951, p. 445. Subfamily diagnosis: obligate tube-dwelling Gastrochaenidae with long, straight-sided tubes; long, largely fused siphons sensu stricto; sparse, minute siphonal papillae on incurrent but not excurrent siphonal aperture; anterior pedal retractor muscles passing around visceral mass as they approach the foot; the ventral surface of the foot elongate-ovate in the lateral direction. This subfamily differs from Spengleriinae and Gastrochaeninae in having obligate tube-dwelling life habits in which the tube is very elongate and straight sided, in lacking papillae on the excurrent siphon, and in having a laterally expanded instead of round to anteroposteriorly elongate ventral pedal surface. This family also contains Kummelia L. Stephenson, 1937.
Hiatellida Carter, herein, ord. nov ., nom. transl. et correct. Carter, herein, ex Hyatelladae J. Gray, 1824, based on Hyatella, an incorrect subsequent spelling of Hiatella Bose ex Daudin MS, 1801; =suborder Saxicavoidea Morretes, 1949, p. 47, invalid, based on the junior synonym Saxicava Fleuriau de Bellevue, 1802 (=Hiatella Bosc ex Daudin MS, 1801). Taxonomic content indicated above.
Joannininae Carter, herein, subfam. nov. Type genus, Joannina Waagen, 1907, p. 94. Subfamily diagnosis: edentulous members of Modiomorphidae differing from sister subfamilies Modiomorphinae and Healeyinae in having more dors ally projecting umbos, better defined anterior auricles, a narrower hinge plate, and, with the exception of Leidapoconcha, a shorter, more external ligament nymph and growth lines not continuing from a lunule onto the subumbonal hinge plate. This subfamily also contains Protopis Kittl, 1904, Waijiaoella Stiller & Chen, 2006, Qingyaniola Stiller & Chen, 2006, and Leidapoconcha Stiller & Chen, 2006.
Ornithopectinidae Hautmann, herein, fam. nov. Type genus, Ornithopecten Cox, 1962, p. 596. Family diagnosis: discs inequilateral, retrocrescent, posteriorly slightly expanded; beaks located well in front of midpoint of dorsal margin; right anterior auricle delicate, with narrow subauricular byssal notch; right posterior wing broad, poorly differentiated but distally pointed; left anterior auricle poorly differentiated, with indistinct auricular sinus; ornament with radial ribs usually intercalated in different ranks, superimposed by regularly spaced commarginal riblets. Comparisons; Ornithopectinidae differs from the closely related Antijaniridae chiefly in the anteriorly positioned beaks, retrocrescent dics, and broad posterior wing. This family is monogeneric.
Ovatoconchidae Carter, herein, fam. nov. Type genus, Ovatoconcha Cope, 1996, p. 988. Family diagnosis; members of superfamily Solemyoidea with anteriorly produced shell, as in Ctenodontidae and Solemyidae, but lacking parivincular nymphs and possibly also lacking palaeotaxodont hinge teeth in adult shell. This family is monogeneric.
Paleodorinae Carter, herein, subfam. nov. Type genus, Paleodora C. Fleming, 1957, p. 943. Subfamily diagnosis; members of family Sanguinolitidae with elongate, subrectangular, slightly sickle-shaped shell with anterior end short and rounded, posterior end longer; posteroventrally rounded and dorsoposteriorly truncate; ornament of low, commarginal ribs, replaced by fine growth lines on the relatively flat, dorsoposterior area; hinge unknown, possibly lacking distinct teeth; sharply elevated, internal shell lamellae radiating from area below beaks anteroventrally and toward the posterior. This subfamily is monogeneric.
Pleuronectitidae Hautmann, herein, fam. nov. Type genus, Pleuronectites Schlotheim, 1820, p. 217. Family diagnosis; discs procrescent, height of valves greater than length, left valve more convex than right; shell exterior smooth or with radial ribs; right anterior auricle with auricular scroll and deep byssal notch; ctenolium present; right posterior auricle obtuse but well delimited, not projecting above hinge margin; auricles of left valve lacking auricular sinuses and dorsally levelling with hinge margin; ligament alivincularalate, small bourrelets may be present; hinge lacking resiliai teeth; shell interior without buttresses; shell with thin, calci tic outer shell layer, divided into radial sectors with irregular foliated to radially irregular spherulitic prismatic to radially fibrous prismatic structure; aragonitic middle and inner shell layers with evidence of linear to slightly branching crossed lamellar structure. Comparisons and comment: Pleuronectitidae differs from other families of Pectinoidea (as defined by the presence of both an alivincular-alate ligament and a ctenolium, thus excluding the Entolioidea) in having procrescent discs, a flat right valve, a well-developed right anterior auricular scroll, and in lacking teeth and internal buttresses. This family tentatively also contains Lower and Middle Triassic Periclaraia Li Jin-hua & Ding, 1981.
Saturnopectininae D. Campbell, herein, subfam. nov. Nom. subst. D. Campbell, herein, pro Saturnellinae Astafieva, 1994, p. 12, 16, invalid, based on Saturnella Astafieva, 1994, a preoccupied name. Type genus, Saturnopecten Astafieva, 2001a, p. 106, 2001b, p. 557, nom. nov. pro Saturnella Astafieva, 1994, non Saturnella Hedinger, 1993 [Foraminifera]. Subfamily diagnosis same as for Saturnellinae in Waterhouse (2008, p. 104); “Distinguished by ornament of strong commarginal rugae, radial ornament absent or very faintly developed over body of shell, and stronger over right anterior auricle in some species.” This subfamily also contains Astafievina Waterhouse, 2008, and Montorbicula Waterhouse, 2008.
Similodontidae Carter & Pojeta, herein, fam. nov. Type genus, Similodonta H. Soot-Ryen, 1964, p. 498. Family diagnosis; members of superfamily Tironuculoidea with low hinge angle (65–100°) and only slightly, if at all, anteroventrally expanded shell. Increased anterior shell gape achieved by orienting ligament axis more nearly perpendicular to the anteroventral shell margins. Anterior hinge teeth convexodont to orthomorphodont and inclined. Posterior hinge teeth convexodont in most genera, to orthomorphodont and inclined. Anterior and posterior tooth rows generally form continuous series below the beaks, but posterior tooth row may overlap anterior tooth row below beaks. Anterior and posterior tooth rows typically nearly equal in length, but the posterior tooth row may be slightly shorter. This family also contains Australonucula Sanchez, 1989, Trigonoconcha Sánchez, 1999, Villicumia Sánchez, 1999, and doubtfully Upper Ordovician Palaeoconcha S. A. Miller, 1889.
Spengleriinae Carter, herein, subfam. nov. Type genus, Spengleria Tryon, 1862a, p. 472, 485. Subfamily diagnosis; obligate endolithic Gastrochaenidae with short to long, entirely separated siphons sensu stricto, and with little or no extension of ctenidia and mantle cavity posterior to shell margins. Beaks slightly to moderately anterior, never far anterior or terminal. Numerous, minute siphonal papillae surround each siphonal aperture. Anterior pedal retractor muscles pass around visceral mass as they approach the sole of the foot; ventral surface of foot nearly circular to elongate-ovate in anteroposterior direction. This subfamily differs from Gastrochaeninae in having siphons sensu stricto that are entirely separated, and by having little or no extension of the ctenidia and mantle cavity posterior to the shell margins. It differs from Eufistulaninae in having entirely separated siphons sensu stricto, and in having obligate endolithic instead of obligate tube dwelling habits. This family also contains Gastrochaenopsis Chavan, 1952c, and Spenglerichaena Carter, gen. nov.
Thraciida Carter, herein, ord nov ., mom. transl. et correct. Carter, herein, ex subfamily Thraciinae Stoliczka, 1870 in 1870–1871, p. 59, 62. Taxonomic content indicated above.
APPENDIX 2. NEW GENERA AND SPECIES
Superfamily Gastro chaenoidea J. Gray, 1840b
Family Gastrochaenidae J. Gray, 1840b
Subfamily Gastrochaeninae J. Gray, 1840b
Stenochaena Carter, herein, gen. nov.
Type species.—Gastrochaena lacera Belokrys, 1991, p. 10.
Discussion .—The genus Stenochaena is presently proposed for Middle Eocene Gastrochaena lacera Belokrys, 1991 (p. 10, pl. 1, 1–3, fig. 1a, 2), from the Dnepropetrovsk region of Ukraine. The name Stenochaena derives from the Greek stenos for narrow, and from a variation of cheniskos for the upturned prow of a boat, as in Gastrochaena. The new genus name is feminine. The name Stenochaena reflects the extremely small pedal gape and boatlike shape of the united valves. In addition to Stenochaena lacera, this genus includes Upper Jurassic Gastrochaena zitteli Boehm, 1883, from Stramberk, Czech Republic, and Jurassic Gastrochaena valfinensis de Loriol, 1888, in de Loriol & Bourgeat, 1886–1888, from Valfin, eastern France (possibly a juvenile of Stenochaena zitteli).
Generic diagnosis and description .—Members of Gastrochaeninae with a greatly posteriorly elongated, small- to medium-sized shell (9.5–38 mm long), with far anterior but not terminal beaks, a very small, anteriorly restricted pedal gape (comprising less than 12% of shell length), and pedal gape margins oriented at a high angle (over 60°) relative to the hinge axis. The shell's posterior is narrowly ovate and ornamented with regularly spaced, erect, commarginal lamellae (Stenochaena zitteli) or irregularly spaced growth lines (Stenochaena lacera). There are no mineralized periostracal spikes or spines cemented to the shell. The boring's shell chamber is subcylindrical, tapering far anteriorly and far posteriorly to conform with the shell’s shape. The anterior half of the siphonal boring appears like a slightly narrower extension of the shell chamber, without a strong constriction in boring width at the base of the siphons. The posterior half of the siphonal boring is divided into incurrent and excurrent areas that diverge at an angle of 20°–25°. The hinge is thin, edentulous, and lacks myophores. Posterior to the beaks, the hinge is slightly convex and nearly parallel with the ventral shell margin; anterior to the beaks, it is very short, dorsally slightly deflected, and laterally strongly deflected (about 60°) from the subumbonal hinge axis. This lateral deflection frames a distinct, triangular opening between the dorsoanterior shell margins. The ligament is opisthodetic and parivincular, with very thin, not strongly dorsally projecting nymphs. The anterior adductor muscle scar is positioned immediately adjacent to the deflected dorsoanterior shell margin. Other muscle scars are not visible, despite excellent preservation of the aragonitic shells.
Comparisons.—No other member of Gastrochaenidae approaches Stenochaena in its combination of a very anteriorly restricted, highangle pedal gape and greatly posteriorly extended, nearly cylindrical shell shape.
Distribution.—Stenochaena is known only from the Upper Jurassic and Middle Eocene of Europe.
Ecology.—Specimens of Stenochaena lacera from Belokrys (1991) came from borings in the dome-shaped coral Astraeopora sphaeroidalis (Mich.). Belokrys speculated that juveniles of this species bored through living coral tissue. Although this cannot be certain, the borings are sometimes partially overgrown by coral, indicating close proximity to living coral tissue at the time of settlement. Calcareous laminae are sometimes present in the anterior of the boring’s shell chamber, indicating that the bivalves sometimes bored in a posterior direction to keep pace with coral growth.
Boehm's (1883) specimen of Stenochaena zitteli came from an Upper Jurassic limestone at Stramberk, Czech Republic (Boehm, 1883, p. 495, pl. 53,6–7). Boehm indicated that his specimen occupied a calcareous tube that is anteriorly thin walled and posteriorly rather thick walled. This putative tube is probably the calcareous lining of a boring, thickened posteriorly to conform with the shell's shape, as in modern endolithic gastrochaenids. The British Museum has in its collections an upper Tithonian, Upper Jurassic specimen of S. zitteli, also from Stramberk (British Museum Geology Department L23855), with impressions of a coral substratum on the exterior of its boring cast.
Superfamily Gastrochaenoidea J. Gray, 1840b
Family Gastrochaenidae J. Gray, 1840b
Subfamily Spengleriinae Carter, herein, subfam. nov.
Spenglerichaena Carter, herein, gen. nov.
Type species.—Gastrochaena apertissima Deshayes, 1855a, p. 326.
Discussion.—The genus Spenglerichaena is presently proposed for Recent, Indo-Pacific Gastrochaena apertissima Deshayes, 1855a, the type species. The name derives from Spengleria and Gastrochaena, in recognition of anatomical similarities with Spengleria and shell similarities, especially the lack of a raised posterior triangular area, with Gastrochaena. The new genus name is feminine.
Generic diagnosis and description.—Members of Spengleriinae with anteriorly strongly laterally inflated shells, moderately anterior umbos, completely divided, relatively long siphons sensu stricto, little or no extension of the ctenidia and posterior mantle cavity posterior to the shell margins, no raised, posterior triangular area, and no distinct umbonal-posteroventral sulcus. The shell posterior has irregular, commarginal growth lamellae and a thin, nonmineralized periostracum. The ctenidia are nonplicate, the pedal probing organ is spatulate, and the calcareous boring linings lack an annular septum and spiny baffles at the base of the siphonal boring.
Comparisons.—Spenglerichaena resembles Spengleria in its completely separated siphons sensu stricto and anterior pedal retractor muscles that pass around the visceral mass as they approach the foot. However, Spenglerichaena lacks the raised posterior triangular area, aragonitic periostracal spikes, distinct umbonal-posteroventral sulcus, pointed calcareous baffles in the boring lining at the base of the siphons, plicate ctenidia, and more medially positioned umbos of Spengleria. Its nonplicate ctenidia, spatulate pedal probing organ, lack of a raised, posterior triangular area, and lack of mineralized periostracal spines are more typical of Gastrochaena and Rocellaria, but in those genera, the siphons sensu stricto and sensu lato are largely fused, and the ctenidia and mantle cavity are extended at least slightly into the siphonal part of the boring, posterior to the shell margins. Spenglerichaena differs from Gastrochaenopsis in having a wider, longer pedal gape, no raised posterior triangular area, and greater lateral inflation of the shell.
Distribution.—Borings similar to those made by Spenglerichaena are known from the Lutetian, Middle Eocene near Verona, Italy, but the associated shells are unknown (Savazzi, 1980). Spenglerichaena is therefore definitely known only from the Recent tropical Indo-West Pacific Region.
Ecology.—Spenglerichaena bores primarily into thicker coral substrata that are less subject to breakage.
Superfamily Modiomorphoidea S. A, Miller, 1877
Family Modiomorphidae S. A. Miller, 1877
Subfamily Modiomorphinae S. A, Miller, 1877
Goniomorpha Carter, herein, gen. nov.
Type species.—Goniophora hamiltonensis J. Hall & Whitfield, 1869, p. 36.
Discussion.—The genus Goniomorpha is presently proposed for sharply carinate, posteriorly obliquely truncate, subumbonally irregularly dentate modiomorphids formerly classified as Megalodon J. de C. Sowerby, 1827, in James Sowerby, 1812–1845, or Goniophora J. Phillips, 1848. The type species is presently designated as Middle Devonian Goniophora hamiltonensis J. Hall & Whitfield, 1869. The name Goniomorpha derives from Gonio- (from Goniophora Phillips, 1848) and morpha (from Modiomorpha J. Hall & Whitfield, 1869). Johnston (1993, p. 76) was aware that “Goniophora” hamiltonensis is “almost certainly not congeneric” with Goniophora J. Phillips, 1848, and he pointed out that it differs from true Goniophora in having a depressed, striated lunule, the growth lines of which continue onto the subumbonal hinge plate, as in Modiomorpha concentrica (Conrad, 1838) (see J. Hall, 1884 in 1883–1884, pl. 43, 18–19; Bailey, 1983, fig. 47; Carter, 1990a, fig. 50A). Carter (1990a, p. 266) indicated that “Goniophora” hamiltonensis belongs in Modiomorphidae, noting that it is microstructurally similar to M. concentrica, and Johnston (1993) also assigned “Goniophora” hamiltonensis to Modiomorphidae.
True Goniophora is a mecynodontid based on upper Silurian Goniophora cymbaeformis Sowerby in Murchison, 1839. This mecynodontid resembles Goniomorpha in having an equivalve, strongly inequilateral, posteriorly elongate shell with simple, commarginal ornament, and a sharp, angular carina extending from the beak to the posteroventral shell margin. However, it differs from Goniomorpha in having prominent anterior and posterior internal ridges (Johnston, 1993, p. 74–76; Liljedahl, 1994, p. 74, fig. 521). The hinge and ligament of Goniophora cymbaeformis are unknown, but other species of this genus differ from Goniomorpha in having a narrower hinge plate, largely restricted to the subumbonal area, with finer, more regularly shaped cardinal teeth, an opisthodetic, parivincular ligament with shorter, more external nymphs, no strong growth lines on the subumbonal hinge plate, and no deeply impressed lunule (Liljedahl, 1994, p. 74).
Goniomorpha hamiltonensis was described and illustrated by J. Hall (1885, p. 296, pl. 43, 8–15, 17–21), Carter and Tevesz (1978), Carter (1990a, p. 266–268, fig. 50), Carter, Lutz, and Tevesz (1990, p. 391), and Johnston (1993, p. 76). Other species presently included in Goniomorpha lack posterior lateral teeth, and they all have at least one, weakly to strongly developed, irregular but more or less triangular cardinal tooth in the left valve. A second, weaker cardinal tooth may be present posterior to the principal cardinal tooth in the left valve, e.g., in Lower Devonian Goniomorpha stuertzi (Beushausen, 1895) (see Maillieux, 1937, p. 136), or a large, rounded cardinal tooth may be present in the right valve, anterior to the right, principal cardinal socket, as in Lower Devonian Goniomorpha cognata (Drevermann, 1902) (see Drevermann, 1902, p. 88, pl. 10, 15–16).
Carter (1990a, p. 266) incorrectly indicated that “Goniophora” hamiltonensis has a very weak left posterior lateral tooth overlapping a weak right posterior lateral tooth. This was based on a misinterpretation of a shallow flexure near the base of the posterior hinge plate in an isolated left valve. Subsequent sections through united valves from the Hamilton Group near Morrisville, New York, along with the observations by C. F. Römer (1844) and Maillieux (1937), indicate a lack of lateral hinge teeth in this genus.
Generic diagnosis and description.—Goniomorpha encompasses members of subfamily Modiomorphinae with a sharply defined, umbonal-posteroventral carina, an angular, rostrate posterior, and no posterior lateral hinge teeth. Like other Modiomorphinae, the shell is equivalved, posteriorly elongate, and strongly inequilateral, with low umbos, a deeply impressed, growth-lined lunule with growth lines extending from the lunule onto a wide, subumbonal hinge plate, a weakly or more strongly developed, irregular, more or less triangular, left cardinal tooth, a flat, wide, posterior hinge plate, and slightly submerged, elongate, parivincular ligament nymphs. In some species, a second, smaller, more posterior, left cardinal tooth is also present, or a rounded cardinal tooth is present in front of the principal cardinal socket in the right valve. The adductors are heteromyarian, the anterior one deeply impressed and positioned just below the hinge, and bounded posteriorly by a low, umbonal ridge or buttress. The posterior adductor muscle scar is more shallowly impressed. The anterior pedal retractor scar is separated from the anterior adductor scar, but the posterior pedal retractor scar is partially confluent with the posterior adductor scar. The palliai line is unknown for the type species, but it was probably integripalliate, judging from other members of Modiomorphinae. The shell mineralogy and microstructure resemble Modiomorpha concentrica, except that mineralized periostracal spikes are fused to the shells exterior anteriorly (see Carter, 1990a, p. 268).
Comparisons.—Goniomorpha resembles Modiomorpha in having a crudely shaped cardinal tooth in the left valve, but Goniomorpha has a more sharply defined posterior carina, a more sharply truncate posterior, a more variable subumbonal dentition, and no posterior lateral teeth. A posterior lateral tooth is variably developed in Modiomorpha (see Carter, 1990a, p. 266).
Distribution.—Goniomrpha includes most of the Lower Devonian species assigned by Maillieux (1937) to Goniophora, e.g., Goniophora bipartita (F. Römer, 1844), G. dorlodoti Asselberghs, 1913, G. trapezoidalis Kayser, 1885, G. schwerdi Beushausen, 1895, G. stuertzi Beushausen, 1895, G. praecedens Drevermann, 1902, G. cognata Drevermann, 1902, G. rhenana Beushausen, 1895, G. stainieri Maillieux, 1937, G. kaisini Maillieux, 1937, and G. atrebatensis Leriche, 1912. It also contains most, if not all, of the New York Middle and Upper Devonian species placed by Hall (1885, p. 293–306) in Goniophora, e.g., Goniophora acuta (Hall & Whitfield, 1869), G. rugosa (Conrad, 1841), G. truncata Hall, 1883 in 1883–1884, G. glaucus (Hall & Whitfield, 1869), G. ida (Hall & Whitfield, 1869), G. carinata (Conrad, 1841), G. trigona Hall, 1885, and G. chemungensis (Vanuxem, 1842).
Paleoecology.—Goniomorpha hamiltonensis occurs in the Middle Devonian Hamilton Group of central New York State in clayrich sandstones also containing a high diversity of other marine invertebrates, especially the bivalves Ptychopteria (Pterineidae), rare pectinoids, and the gastropods Palaeozyglopleura and Bembexia. Goniomorpha hamiltonensis is not usually found in large concentrations. The strongly and sharply truncate, elongate posterior and lack of a distinct byssal notch suggest a shallow infaunal life habit, with the shell's posterior end at or just above the sediment-water interface. The species is never associated with abundant nuculoids and muddy, fine grained sediments, suggesting suspension feeding habits and low tolerance of resuspended, muddy substrata.
Superfamily Ostreoidea Rafinesque, 1815
Family Arctostreidae Vialov, 1983
Subfamily Palaeolophinae Malchus, 1990
Nacrolopha Carter & Malchus, herein, gen. nov.
Type species.—Nacrolopha carolae Carter & Malchus, herein, gen. et sp. nov.
The new genus Nacrolopha is presently proposed for the new species, Carnian, Upper Triassic Nacrolopha carolae Carter & Malchus (Fig. 4), with the holotype of the latter being a well-preserved left valve from Alpe di Specie, Cassiano Formation (alt. 1900–2000 m), Italy (UNC 13497b). The holotype was described and illustrated as an unknown genus and species by Carter (1990a, p. 217–220, fig. 32). The genus name derives from the nacreous microstructure and Lopha-like shape of the type species. The species is dedicated to Carol Elizabeth Via Carter. The holotype, which has been sectioned for microstructural analysis, is deposited in the paleontological collection of the Yale University Peabody Museum of Natural History, New Haven, Connecticut.
Generic and species diagnosis.—Nacrolopha is characterized by a posteriorly instead of posterodorsally positioned posterior adductor scar, a posterior pedal retractor scar that is partially confluent with the posterior adductor scar, a minute, anterior adductor scar, and a nacroprismatic left valve that lacks foliated structure, structural chambering, and chalky deposits. This diagnosis applies to the genus and to its type species.
Generic and species description.—The following description of N. carolae is based on left valve UNC 13497b. The beak is prosogyrate in the juvenile stage and orthogyrate in the adult stage. The hinge is slightly arched and smooth except for 9 shallow pits (possible preparation artifacts) posterior and ventral to the cardinal area. There are no chomata. The ventral and lateral internal shell margins vary from nearly smooth to slightly radially costate. The exterior has about 25 coarse, radial costae immediately adjacent to the attachment area; these increase to about 30 at the shell margins through intercalation and branching, but mostly through intercalation. A palliai line is not visible, but this could be covered by an attached brachiopod and adherent sediment. The posterior adductor muscle scar (5.1 × 3.5 mm) is ovate, higher than wide, and much larger than the anterior adductor muscle scar (1.4 × 0.8 mm); both scars are positioned near their respective shell margins, and both are elevated by a shelly buttress, that supporting the anterior adductor being more prominent by virtue of its position on a more steeply inclined shell surface. The posterior pedal retractor scar measures 1.2 × 1.0 mm, and its center is 40% from the ventral shell margin toward the dorsal end of the shell. The ligament insertion area is acutely triangular and alivinculararcuate, with the fibrous attachment area distinctly impressed below narrow, distinct, anterior and posterior bourrelets. The “incipient” crura that Carter (1990a, p. 219) described for this specimen are actually the flanks of the alivincular-arcuate ligament (Hautmann, 2004, 2006). The ligament insertion area is covered by a very thin aragonitic ligostracum of nearly vertical irregular simple prisms (ISP) and steeply dipping fibrous prisms. The underlying hinge is nacreous. The outer shell layer is very thin and varies from ISP to regular simple prismatic to homogeneous mosaic, with prisms 6–10 µm wide. The middle shell layer is nacreous and closely approaches the shell margins. Where marginal radial folds are present, the nacreous laminae are strongly reflected outward. The adductor myostracum is finely ISP. The inner shell layer is aragonitic and mostly coarsely textured ISP, with minor nacreous lensatic sublayers.
Comparisons.—Nacrolopha carolae differs from all other presently known members of Palaeolophinae in having nacre, an anterior adductor muscle scar, and a posterior pedal retractor scar. Because these features are internal, the composition of the genus is poorly known. Palaeolopha montiscaprilis (Klipstein, 1843) (Klipstein, 1843, p. 247, pl. 16, 5) appears externally similar to N. carolae (see also Wöhrmann, 1889, p. 200, pl. 6, 1–3), but illustrations of that species do not show an anterior adductor or posterior pedal retractor muscle scar. Possible congeners of Nacrolopha include certain other species assigned by Malchus (1990) to Palaeolopha, such as Carnian, Upper Triassic Palaeolopha mediocostata (Wöhrmann, 1889), and Palaeolopha calceoformis (Broili, 1904). However, these species are unknown both microstructurally and in the details of their muscle scars.
The presence of ISP and homogeneous mosaic structure in the outer shell layer of the left valve of N. carolae resembles some Triassic bakevelliids and gryphaeids, e.g., the Middle Triassic bakevelliid Hoernesia socialis (Schlotheim, 1823 in 1822–1823) (Carter, 1990b, p. 337) and the Upper Triassic gryphaeid Gryphaea nevadensis McRoberts, 1992 (McRoberts & Carter, 1994). Some Jurassic gryphaeids retained homogeneous mosaic structure in their outer shell layer, typically between an RSP outermost sublayer and the foliated middle shell layer, e.g., in Jurassic Gryphaea arcuata (Lamarck, 1801) and in Praeexogyra hebridica (Forbes, 1851) (Carter, 1990c, p. 356–359).
The dorsally rounded posterior adductor muscle scar in N. carolae resembles Gryphaeidae and differs from the dorsally flattened or concave posterior adductor scar in Ostreidae (Harry, 1985).
Nacrolopha carolae resembles Norian—Rhaetian, Upper Triassic Umbrostrea emamii Hautmann, 2001b, from the Nayband Formation of Iran, in having some calcitic RSP in its outer shell layer and nacre in its inner shell layers. However, U. emamii differs in having a regularly to irregularly foliated instead of nacreous middle shell layer. In U. emamii, the outer layer of the right valve is RSP to slightly ISP, whereas that of the left valve is coarsely ISP (Hautmann, 2001b, pl. 7; 2006). Structural chambers are lacking in the foliated layer. Umbrostrea lacks an adult anterior adductor muscle scar and adult posterior pedal retractor muscle scars (Hautmann, 2001b).
Distribution.—Nacrolopha carolae is presently known only from the Carnian, Upper Triassic, Cassiano Formation at Alpe di Specie, Italy.
APPENDIX 3. CLASSIFICATION ABOVE FAMILY RANK
APPENDIX 4. AUTHOR ADDRESSES
Cristian R. Altaba, Laboratori de Sistemàtica Humana, Universitat de les Illes Balears, 07122 Palma, Balearic Islands, Spain, email@example.com Laurie C. Anderson, South Dakota School of Mines and Technology, 501 East Saint Joseph Street, Rapid City, South Dakota 57701-3901, USA, Laurie.Anderson@sdsmt.edu
Rafael Araujo, Museo Nacional de Ciencias Naturales, José Gutiérrez Abascal 2, 28006, Madrid, Spain, firstname.lastname@example.org
Alexander S. Biakov, Chief of Laboratory of Stratigraphy and Tectonics, North-East Interdisciplinary Scientific Research Institute (NEISRI), Far East Branch, Russian Academy of Sciences, Portovaya Street, 16, 685000, Magadan, Russia, email@example.com
Arthur E. Bogan, Research Laboratory, North Carolina State Museum of Natural Sciences, Mail Service Center 1626, Raleigh, North Carolina 276991626, USA, firstname.lastname@example.org
David C. Campbell, Paleontological Research Institution, 1259 Trumansburg Road, Ithaca, New York 14850, USA, email@example.com
Matthew Campbell, Department of Biology, Charleston Southern University, 9200 University Boulevard, Charleston, South Carolina 29406, USA, firstname.lastname@example.org
Joseph G. Carter, Department of Geological Sciences, University of North Carolina, Chapel Hill, North Carolina 27599-3315, USA, email@example.com
Chen Jin-hua, Nanjing Institute of Geology and Palaeontology, Academia Sinica, Nanjing, 210008, Peoples Republic of China, firstname.lastname@example.org
John C. W. Cope, Department of Geology, National Museum of Wales, Cardiff CF10 3NP, UK, email@example.com
Graciela Delvene, Instituto Geológico y Minero de España, C/. Ríos Rosas, 23 28003, Madrid, Spain, firstname.lastname@example.org
Fang Zong-jie, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, People's Republic of China, email@example.com
Ronald N. Gardner, 19B Cheam St, Dallington, Christchurch 8061, New Zealand, firstname.lastname@example.org
Vera A. Gavrilova, Russian Geological Research Institute (VSEGEI), Sredniy pr, 74, 199106, St. Petersburg, Russia, Vera_Gavrilova@vsegei.ru
Irina A. Goncharova, Mollusk Laboratory, Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya ul. 123, Moscow, 117997, Russia, email@example.com
Joseph H. Hartman, Department of Geology and Geological Engineering, University of North Dakota, 81 Cornell Street Stop 8358, Grand Forks, North Dakota 58202, USA, Joseph.firstname.lastname@example.org
Michael Hautmann, Wissenschaftlicher Mitarbeiter, Paläontologisches Institut und Museum, Karl-Schmidt-Strasse 4, CH-8006, Zürich, Switzerland, email@example.com
Walter R. Hoeh, Department of Biological Sciences, Kent State University, Kent, Ohio, 44242, USA, firstname.lastname@example.org
Jorgen Hylleberg, Institute of Biology, Bygning 1135, Ole Worms alle 1, 8000 Aarhus C, Denmark, email@example.com
Jiang Bao-yu, Department of Earth Sciences, Nanjing University, 22 Hankou Road, 210093, Nanjing, People's Republic of China, firstname.lastname@example.org
Paul Johnston, Department of Earth Sciences, Mount Royal University, 4825 Mount Royal Gate SW, Calgary, Alberta, Canada T3E 6K6, email@example.com
Lisa Kirkendale, University of Wollongong, Shoalhaven Marine and Freshwater Centre, West Nowra, 2541, New South Wales, Australia, firstname.lastname@example.org
Karl Kleemann, Centre for Earth Sciences, University of Vienna, Althanstrasse 14, A1090 Vienna, Austria, Karl.Kleemann@univie.ac.at
Jens Koppka, Paléontologie A16, République et Canton du Jura, Office de la Culture, Section d'Archéologie et Paléontologie, Hôtel des Halles, Case postale 64, CH-2900 Porrentruy 2, Switzerland, email@example.com
Deusana Machado, Departamento de Ciências Naturais, ECB, CCBS, Universidae do Rio de Janeiro, Av. Pasteur, 428, Urca, Rio de Janeiro, Brazil, firstname.lastname@example.org
Ana Márquez-Aliaga, Instituto Cavanilles de Biodiversidad y Biologia Evolutiva and Departamento de Geología, Universitat de València, Dr. Moliner 50, E-46100, Burjassot, Valencia, Spain, email@example.com
Jean-Pierre Masse, Laboratoire de Géologie des Systèmes et des Reservoirs Carbonatés, Université de Provence, 13331, Marseilles Cedex 03, France, Jean-Pierre.Masse@up.univ-mrs.fr or firstname.lastname@example.org
Christopher A. McRoberts, Department of Geology, State University of New York at Cortland, P.O. Box 2000, Cortland, New York, 13045, USA, Christopher.McRoberts@cortland.edu
Peter U. Middelfart, Malacology, Australian Museum, 6 College Street, Sydney 2010, Australia, Peter. Middelfart@austmus.gov.au
Simon Mitchell, Department of Geography and Geology, The University of the West Indies at Mona, Jamaica, email@example.com
Lidiya A. Nevesskaja (deceased), Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya ul. 123, Moscow, 117997, Russia
Sack Özer, Dokuz Eylül University, Engineering Faculty, Geological Engineering Department, 35160, Buca Campus, Izmir, Turkey, firstname.lastname@example.org
John Pojeta, Jr., Department of Paleobiology, Museum of Natural History, P.O. Box 37012, NHB MRC 121, Smithsonian Institution, Washington, D.C, 20013-7012, USA, email@example.com
Inga V. Polubotko, Russian Geological Research Institute (VSEGEI), Sredniy pr. 74, 199106, St. Petersburg, Russia, contact person: Vera A. Gavrilova, Vera_Gavrilova@vsegei.ru
Sergey Popov, Mollusk Laboratory, Palaeontological Institute, Russian Academy of Sciences, Profsoyuznaya ul. 123, 117997, Moscow, Russia, firstname.lastname@example.org
Teresa Sánchez (deceased), Centro de Investigaciones en Ciencias de la Tierra, Universidad Nacional de Córdoba y Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Velez Sársfeld 299, 5000 Córdoba, Argentina
André F. Sartori, Division of Invertebrates, Department of Zoology, Field Museum of Natural History, 1400 S. Lake Shore Drive, Chicago, Illinois, 60605-2496, USA, email@example.com
Robert W. Scott, Precision Stratigraphy Associates, 149 West Ridge Road, Cleveland, Oklahoma, 74020, USA, and University of Tulsa, 800 S. Tucker Dr., Tulsa, Oklahoma 74104, USA, firstname.lastname@example.org
Irina I. Sey, Russian Geological Research Institute (VSEGEI), 74 Sredniy pr, 74, 199106, St. Petersburg, Russia, contact person: Vera A. Gavrilova, Vera_Gavrilova@vsegei.ru
Javier H. Signorelli, Centro Nacional Patagonico (CENPAT) Biología y Manejo de Recursos Acuáticos, Bvd. Brown 2915 (U9120ACD) Puerto Madryn, Argentina, email@example.com
Peter W. Skelton, Department of Earth and Environmental Sciences, Open University, Walton Hall, Milton Keynes, MK7 6AA, UK, P.W.Skelton@open.ac.uk
Thomas Steuber, The Petroleum Institute, Abu Dhabi, United Arab Emirates, firstname.lastname@example.org
J. Bruce Waterhouse, 25 Avon St, Oamam, New Zealand, email@example.com
G. Lynn Wingard, U.S. Geological Survey, 926A National Center, Reston, Virginia, 20192, USA, firstname.lastname@example.org
Thomas Yancey, Department of Geology and Geophysics, MS 3115, Texas A & M University, College Station, Texas, 77843, USA, email@example.com