142


Journal of Paleontology 92(2):130–145


Etymology.—Honoring Frederick E. Edwards, the discoverer of this species.


Remarks.—This species was mentioned previously by a few authors as Cardilia radiata from exposures of the Barton and the Bracklesham Beds (Tennant, 1847, p. 29; Beet–Jukes, 1857, p. 530; Newton, 1891, p. 85). Although this species was attributed to either Edwards or Sowerby, it is not listed by Petit (2009) as a taxon named by Sowerby and not found published in the “Quarterly Journal of the Geological Society of London” by Edwards (1854). Cardilia radiata appears in a manuscript name of F.E. Edwards that was never validated. In this work, it is formally described as Cardilia edwardsi new species from the Becton Formation, Barton Group.


Discussion


Literature search allows an understanding of the geographical and temporal radiation of the family Cardiliidae. Extant species were historically sampled from the western Pacific Ocean in the Philippines, Indonesia, China, and Malaysia and the Indian Ocean/Persian Gulf in Oman and Qatar. From this huge area, only three valid species are recognized: C. semisulcata, C. inermis, and C. martini. Cardilia atlantica is the fourth living species registered in the Atlantic Ocean. On the other hand, from 14 names found in the literature for species only known as fossils, 11 are recognized as valid. Five valid species were registered from the fossil record of Europe, one of them formally described herein. They were registered from different localities in England, France, Austria, Italy, and Russia, among others. The stratigraphic range of these records goes from middle Eocene to late Pliocene. They are: Cardilia deshayesi from middle Miocene exposures at Steinebrunn, Vienna Basin, Austria; Cardilia michelottii from Pliocene deposits at Asti, Italy; Cardilia michelini described from Bartonian (middle Eocene) deposits exposed at La Chapelle-en-Serval, Oise, France; Cardilia laeviuscula from Lutetian (middle Eocene) strata, Bracklesham Bay, West Sussex, England; and Cardilia edwardsi n. sp. from the Becton Formation, late Bartonian, middle Eocene of Hampshire, England. Finally, the family Cardiliidae was recorded in the fossil


record of Asia from where seven species have been described: four from Indonesia, one from Brunei and two from Japan. These are C. sundaica Van Regteren Altena and Beets, 1945; C. bruneiana and C. palembangensis, both described by Beets in 1944; C. krawangensis and C. ludwigi, both described by Oostingh in 1934; and Cardilia yudaensis Otuka, 1934 and Cardilia toyamaensis Tsuda, 1959 from Japan. The species


Cardilia yudaensis, described by Okuta (1934, p. 620, pl. 48, figs. 46–48), was reported from lower Kadonosawa Series, Yuda, Iwate Prefecture, Japan. The author placed this species with doubts within the genus Cardilia, although he considered it as the most adequate. However, we conclude that after revision of the original description and illustration, the species Cardilia yudaensis must be excluded from the genus Cardilia due to the inequivalve form of the type material. Two nominal subspecies (Cardilia michelini asiana and


Cardilia michelini georgiana) are recorded in the Global Names Index portal (http://www.gni.globalnames.org/name_strings),


as described by Korobkov (1971). However, these names are not found within the publication (S. Popov, personal commu- nication, 2016). In addition, type material of either taxon has not been deposited into the collection of Saint Petersburg Central Geological Museum, where Korobkov´s types are (S. Popov, personal communication, 2016). Therefore these names are considered invalid. All species belonging to the genus Cardilia have three


different ornamental areas (OA) on the external surface of the shell. The first one (OA1) is the escutcheon: dorso–posterior, concentric, uniformly separated, lamellar, nodular towards the top, and intersecting the first ribs of the second ornamental area. It extends from the posterior side of the umbo to the mid- posterior end of the shell. The second area (OA2) has narrow ribs disposed along the postero-dorsal axis from the umbo to the ventral edge and is delimited by a straight line that separates this area from the contiguous one. The number of ribs of this area is variable. The third and final area (OA3) covers almost the entire external surface and is composed fine and irregular growth lines that become invisible along the ventral edge. This area extends from the straight line towards the anterior side of the shell. The morphologies of these areas have taxonomic value for the identification of the different species of the genus. In addition, the outline of the shell plays an important role in the identifi- cation of Cardilia species. Hinge morphology of all examined species is very conservative with the strong inverted V–shaped cardinal tooth obliquely anteriorly directed in the left valve, which is complementary to the prominent, triangular, and bifid cardinal tooth (3a) of the right valve; additionally, with a second cardinal tooth (3b) in the right valve and a small and rudimen- tary anterior lateral tooth (LAi). Many works had been revised morphologically and


genetically the phylogeny of the related families Mactridae and Mesodesmatidae (Giribet and Wheeller, 2002: Taylor et al., 2007; Combosch et al., 2017, among others). The superfamily Mactroidea was traditionally considered to be a well-supported monophyletic group with a sister group, Cardioidea. Taylor et al. (2007) agreed with the monophyletic concept of Mac- troidea, but suggested a potential sister group with Ungulinidae, and the group Veneridae/Corbiculidae/Arcticidae, and Chami- dae, but with no connection with Cardioidea. Within this con- text, the phylogenetic position of Cardiliidae within Mactroidea is uncertain. The first records of mactrids date from the Early Cretaceous


(Aptian). In a detailed study of hinge development, Saul (1973) suggested that mactrids are derived from the Arcticidae. Cre- taceous Mactridae are characterized by a moderate development of resilifer with two cardinals in each valve and long laterals. This kind of hinge was also observed in the Arcticidae, however in Cenozoic Mactridae this similarity is masked due to the enlargement of the resilifer. The systematic position of Cardi- liidae within Mactroidea was historically based on similarities of the hinge structure and resilifer. As noted by Keen (in Moore, 1969) and subsequent authors, these similarities include a similar pattern of cardinal and lateral teeth with an external ligament small or wanting, and an internal ligament seated in a resilifer.


There are no new data on anatomy, reproduction, and ecology of Cardiliidae. Thus, the conventional position within


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148  |  Page 149  |  Page 150  |  Page 151  |  Page 152  |  Page 153  |  Page 154  |  Page 155  |  Page 156  |  Page 157  |  Page 158  |  Page 159  |  Page 160  |  Page 161  |  Page 162  |  Page 163  |  Page 164  |  Page 165  |  Page 166  |  Page 167  |  Page 168  |  Page 169  |  Page 170  |  Page 171  |  Page 172  |  Page 173  |  Page 174  |  Page 175  |  Page 176  |  Page 177  |  Page 178  |  Page 179  |  Page 180  |  Page 181  |  Page 182  |  Page 183  |  Page 184  |  Page 185  |  Page 186  |  Page 187  |  Page 188  |  Page 189  |  Page 190  |  Page 191  |  Page 192  |  Page 193  |  Page 194  |  Page 195  |  Page 196  |  Page 197  |  Page 198  |  Page 199  |  Page 200  |  Page 201  |  Page 202  |  Page 203  |  Page 204