Palaeodiversity 1: 167–179; Stuttgart, 30.12.2008. 167 Parsemileites n. gen., a new genus of the ammonite family Otoitidae MASCKE from the Lower Bajocian (Middle Jurassic) of Southern England with new information on the Otoitidae from Southern England VOLKER DIETZE & ROBERT B. CHAN D LER Abstract A new Lower Bajocian (Middle Jurassic) ammonite genus Parsemileites n. gen. [M and m] (type-species: Doci­ doceras liebi MAUBEUGE ) is erected that represents a separate phyletic strand within the family Otoitidae MASCKE , 1907 in the Ovale Zone and the lower Trigonalis Subzone of the Laeviuscula Zone. New information on the evolu- tion of the Otoitidae in Southern England is presented. K e y w o r d s : Parsemileites, Emileia, Otoites, Emileites, sexual dimorphs, evolution, Laeviuscula Zone. Zusammenfassung Die hier neu aufgestellte Gattung Parsemileites n. gen. [M und m] (Typus-Art: Docidoceras liebi MAUBEUGE ) stellt einen eigenständigen Entwicklungsstrang innerhalb der Familie Otoitidae MASCKE , 1907 in der Ovale-Zone und der unteren Trigonalis-Subzone der Laeviuscula-Zone (Unter-Bajocium, Mittlerer Jura) dar. Neue Erkenntnisse über die Entwicklung der Otoitidae in Südengland werden bekannt gemacht. Contents 1. Introduction . 167 2. A new genus of the family Otoitidae MASCKE : Parsemileites n. gen.. 168 Parsemileites n. gen. liebi (MAUBEUGE , 1955) [M]. 171 Parsemileites n. gen. cricki (PARSONS , 1977) [m]. 171 3. Emileia BUCK M AN , Otoites MASCKE , and Emileites BUCK M AN in Southern England . 173 3.1. Emileia BUCK M AN and Otoites MASCKE . 173 3.2. Emileites BUCK M AN . 175 4. References. 176 1. Introduction having been described in 1818 by J. SOWERBY from Southern England. The lectotype of this species is produced here as Southern England is a classic area for researching am- a photograph for the first time (Pl. 1, Fig. 1a–c). monites of the family Otoitidae MASCKE , 1907. S. S. BUCK - The relationship between Emileia and Emileites is of M AN (1909–1930) erected in his (Yorkshire) Type Ammo- particular interest in that these different morphogenera nites (TA) several new taxa included in the family Otoiti- represent either different taxa or a striking example of dae and PARSONS (1977) presented new conclusions on the developmental polymorphism sensu MATY J A (1986). The phylogeny of the group. results are of general importance for ammonite classifica- New, precise bed-by-bed collections made over the tion as other examples of parallel ranging ‘micro- and years from most of BUCK M AN s (1893) classical sites have macromorphs’ have also been identified including: Mol­ yielded large numbers of otoitid ammonites. We present listephanus and Stephanoceras, Berbericeras and Mor­ evidence that supports the separation of some of the am- phoceras, Abbasites and Erycites, and within the genus monites formerly included into Emileites into a new genus, Witchellia. The world-wide distribution of the Otoitidae Parsemileites. A more complete interpretation of the phy- makes the family important for correlation between dif- logeny of other members of the family, whose biostratigra- ferent faunal realms. phy is now much better understood, will require further The ammonites collected by the authors have been do- study before the relationships are evaluated. Descriptions nated to the Sedgwick Museum, Cambridge (SM – coll. of other faunas including Docidoceras, Trilobiticeras, RBC, currently in the care of the co-author) and to the Emileia, Emileites and Otoites will follow. The type-species Staatliches Museum für Naturkunde Stuttgart (SMNS – of the genus Emileia BUCK M AN , 1898 is Ammonites brocchii, coll. VD). 168 P ALAEO D I V ERSITY 1, 2008 Acknowledgements the Laeviuscula Zone, Lower Bajocian, Middle Jurassic. SA D KI We thank R. BÖTTCHER (Stuttgart), W. ETTER (Basel), A. V. (1996) reports specimens from the central High Atlas of Mo- HILLEBRAN D T (Berlin), J. HUXTABLE (Taunton), C. PARSONS (Lon- rocco from comparable levels. At Cabo Mondego (Portugal) the don)†, A. PRIEUR (Lyon), L. STEEL (London), J. WHICHER (York) genus is restricted to the Ovale Zone (FERNÁN D EZ -LÓ P EZ et al. for valuable help. Special thanks are due to the reviewers A. 1988). GÁLACZ (Budapest) and S. FERNÁN D EZ -LÓ P EZ (Madrid) and to the R e c o r d s : Southern England (PARSONS 1977, CHAN D LER et land owners and tenants: E. DIGBY (Sherborne Castle Estates), J. al. 2006, DIETZE et al. 2007), Southern France (DOU V ILLÉ 1884), LARWOO D & H. POWELL (Natural England), the Woodland Trust, Spain (SAN D O V AL 1983), Portugal (FERNÁN D EZ -LÓ P EZ et al. 1988), Winchester College, B. LOCK (Sherborne), R. LOXTON (Bradford Morocco (SA D KI 1994), Southern Germany (coll. V. DIETZE , un- Abbas), R. HILLIER (Sherborne), D. TOLLEY (Stoke Knapp), J. published), ?Iran (SEYE D -EM A M I 1967), ?Tibet (ARKELL 1953). SIBLEY (Beaminster) and D. SOLE (Axminster). We are indebted to L. STEEL of the Natural History Museum, London for organis- D i a g n o s i s . – Extremely small ammonites. Adult ing photographs of specimens in the collections. We thank the macroconchs attain diameters of ~50 mm maximum, adult Wessex Cephalopod Club in particular J. CALLO M ON (London), microconchs of ~28 mm maximum. Inner whorls of both A. ENGLAN D (London) and M. HIGGINS (Mapperton) for assis- tance in the field. are cadiconic with a broad, depressed cross section. The prominent primary ribs persist to the end of the body Abbreviations chamber and are terminated by small spines or tubercles. * type specimen The dense secondary ribs, about three to five per primary, Aa Aalenian start at the broadest part of the shell and cross the venter Bcº body chamber length in degrees uninterruption. The bodychamber is about 75 % to 100 % Bj Bajocian D preserved diameter of specimen (mm) of the last whorl. HT holotype Comparisons with related taxa. – Macro- [M] macroconch ammonite species conch Parsemileites n. gen., Emileites and the circum-Pa- [m] microconch ammonite species cific Pseudotoites are closely related. The difference is the Pn number of primary ribs on last preserved whorl Ud umbilical diameter (mm) much smaller adult size of complete adult Parsemileites Wb whorl breadth at the end of preserved specimen (mm) n. gen. compared to adult and complete Emileites and Wh whorl height at the end of preserved specimen (mm) Pseudotoites. The holotype of Emileites malenotatus BUCK M AN (TA Acronyms of repositories 6, pl. 702; Fig. 1a–b), type species of the genus Emileites, BMNH Natural History Museum, London is completely septate to a maximum diameter of 42 mm, GSM Geological Survey Museum, Keyworth, Nottingham SMC Sedgwick Museum, Cambridge this being almost the maximum size of macroconch of SMNS Staatliches Museum für Naturkunde Stuttgart Parsemileites n. gen. with about one whorl of bodycham- ber (Figs. 1e–f, 3a–p, 4l). Macroconch Parsemileites n. gen. retains a cadiconic morphology to the end of the 2. A new genus of the family Otoitidae MASCKE : bodychamber. The whorl section becomes slightly less Parsemileites n. gen. depressed and more circular at the end. Bullae-like tuber- cles at the lateral edge persist throughout. In contrast Suborder Ammonitina HYATT , 1889 Emileites has a more planulate and egreding bodycham- Superfamily Stephanoceratoidea NEU M AYR , 1875 ber, lacking the bullae-like primaries (Fig. 1c–d, g–h), but Family Otoitidae MASCKE , 1907 possessing either short, accentuated, or long persisting primaries. The adult size of complete Emileites can reach Genus Parsemileites n. gen. [M and m] more than double of the adult size of Parsemileites n. gen. (Fig. 1). Ty p e s p e c i e s : Docidoceras liebi MAUBEUGE , 1955. “Australasian” Pseudotoites (type species Stephano­ D e r i v a t i o n o f n a m e : To indicate the close resem- ceras leicharti NEU M AYR , refigured in SP ATH 1939: pl. 1, blance to Emileites and in memoriam to COLIN FRE D RICK PARSONS (1945–2008) †, highly regarded researcher of ammonites and fig. 1; pl. 2, fig. 4; for examples see ARKELL & PLAY F OR D stratigraphy of the Inferior Oolite. 1954; proposals for a revision see HALL 1988) show, with I n c l u d e d s p e c i e s : Docidoceras liebi MAUBEUGE [M] the exception of larger adult size, a close resemblance to and Trilobiticeras cricki PARSONS [m]. We use in this investiga- Parsemileites n. gen., however the bodychamber of tion the morphospecies concept and keep thus the morphological different micro- and. macroconchs separated. In a biological Parsemileites n. gen. never becomes planulate and evolute sense these sexual dimorphs belong to the same biospecies. The as in some “Australasian” Pseudotoites. The “Andean and dimorphic partnership is based upon both having identical inner Alaskan” Pseudotoites (WESTER M ANN & RICCAR D I 1979, whorls of dimorphs (Fig. 4k, l), extremely small size of adult WESTER M ANN 1969) show a greater variability ranging specimens of both dimorphs (Fig. 3, 4) and the identical strati- graphical range of both morphospecies. from sub-planulate and evolute to moderately cadiconic S t r a t i g r a p h i c a l r a n g e : In Southern England from and more involute, apparently with all stages of ontogeny the Ovale Zone (Bj-5) to the lower Trigonalis Subzone (Bj-7b) of represented (for details see WESTER M ANN & RICCAR D I 1979: D IETZE & CHAN D LER , A NEW GENUS O F THE A mm ONITE F A M ILY OTOITI D AE 169 Fig. 1. a–b. Emileites malenotatus BUCK M AN [M], holotype; partly preserved phragmocone of a larger specimen lacking bodycham- ber. Figured for comparison is c–d (with part of the bodychamber) and g–h (complete to the mouthborder).