Cairns—New flabellid genus from Australian Cenozoic
Table 1. Number of species and distribution of the 14 Recent and fossil flabellid genera. Genus
Cycloflabellum Chevalier, 1961 Falcatoflabellum Cairns, 1995 Flabellum Lesson, 1830 Javania Duncan, 1876
Rhizotrochus Milne Edwards and Haime, 1848 4: Indo-West Pacific; 0–1,050m Truncatoflabellum Cairns, 1989b
Placotrochus Milne Edwards and Haime, 1848 1: Indo-West Pacific; 6–289m Polymyces Cairns, 1979
Monomyces Ehrenberg, 1834 Periplacotrochus, n. gen. Placotrochides Alcock, 1902
Blastotrochus Milne Edwards and Haime, 1848 1: Southwest Pacific; 11–62m Conosmilia Duncan, 1865
Adkinsella Wells, 1933
0 0
4: Indo-West Pacific; 80–1,628m
2: Mediterranean, New Zealand; 5–410m 0
1: Southwest Pacific; 366–402m 42: Cosmopolitan; 36–3,186m 10: Cosmopolitan; 30–2,165m
0 3: worldwide, except E. Atlantic; 69–1,203m
409
Number of Recent species: geographic range; depth range
Number of fossil species: stratigraphic range and occurrence
1: lower Cretaceous (Texas)
6: middle Miocene (Victoria, Australia) 1: lower Pliocene (Morocco)
0
~150: Upper Cretaceous–Pleistocene (worldwide) 3: Eocene–Miocene (Tonga, Italy) 0
0 32: worldwide, except W. Atlantic; 2–3,010m 6: middle Eocene–Pleistocene (New Zealand, SWPacific)
7: lower Eocene–middle Miocene (Victoria, Tasmania) 0 0 0 0
Repositories and institutional abbreviations.—NHMUK: The Natural History Museum, UK, London; NMNH: National Museum of Natural History, Smithsonian Institution, Washington DC; NMV: National Museum of Victoria, Victoria, Australia; USGS: United States Geological Survey; USNM: United States National Museum (now the NMNH), Washington DC. Many of the specimens reported as new records herein originate from a gift to the Smithsonian from F. A. Cudmore in April 1923.
Systematic paleontology
Class Anthozoa Ehrenberg, 1834 Order Scleractinia Bourne, 1900 Family Flabellidae Bourne, 1905
Diagnosis.—Corallum solitary, fixed, free, or transversely dividing. Wall epithecal (neotenic condition), sometimes sec- ondarily thickened with stereome. Epitheca usually smooth, lacking costae. Septa imperforate, composed of a single fan system of numerous closely spaced trabeculae, which produces a smooth axial edge. Pali, dissepiments, and synapticulae absent; paliform lobes present on one genus. Columella usually rudimentary or absent, but may be lamellar, papillose, or fasci- cular. Exclusively azooxanthellate.
Occurrence.—Lower Cretaceous to Recent: worldwide, including off Antarctica, 0–3,186 m.
Remarks.—The family was most recently revised by Cairns (1989b, table 4), who tabularized the characteristics of the var- ious genera. Table 1 is an update and expansion of that compi- lation, the family now consisting of 14 genera: seven exclusively Recent, four exclusively fossil, and three having both components. 100 Recent species are known in the family (Cairns and Hoeksema, 2015, table 1), making it the fifth-most species-rich family among the 24 families that contain Recent species in the Scleractinia (Cairns, 1999), and containing about 7% of the living species. Approximately 174
fossil species are known (Table 1); however, the total number of fossil species in the approximately 85 families that contain fossil species is not well known, and thus similar ranking cannot be made for the fossil species. In the first broadly based phylogenetic analysis of the
Scleractinia using molecular sequencing, Kitahara et al. (2010) supported the monophyly of the family Flabellidae but found polyphyletic assemblages among the three multispecies genera they analyzed (i.e., Flabellum, Truncatoflabellum, Javania), implying that the morphological distinctions of these genera may not be accurate. However, Kitahara et al. (2010, p. 4), even though professing to include “species representing the full morphological spectrum of the family,” included species fromonly four of the 10 Recent genera, and of course none fromthe four exclusively fossil genera. Furthermore, only one mitochondrial gene was used in the analysis, which is usually not considered to be adequate for phylogenetic analyses. Finally, their conclusion that the trans- versely dividing genera (e.g., Truncatoflabellum) were antecedent to those with a pedicellate base (e.g., Flabellum) contradicts the fossil record, wherein Flabellum has the oldest fossil occurrence. Thus, based on these three reasons, the morphological distinction of genera is favored in this paper and is the only one that can be used with fossils.
Genus Periplacotrochus new genus
1864 Placotrochus; Duncan, p. 163, 164, 166–167 (in part). 1884 Placotrochus; Duncan, p. 16 (in part). 1943 Placotrochus; Vaughan and Wells, p. 227 (in part). 1956 Placotrochus;Wells, p. F432 (in part).
1989b “Placotrochus” deltoideus species complex; Cairns, p. 44, 45.
Type species.—Placotrochus deltoideus Duncan, 1864, here designated.
Diagnosis.—Corallum solitary, shaped as a laterally com- pressed fan; edge spines lacking but may have low thecal crests.
Figure 1. The four permutations or categories of genera resulting from the character states of two characters: presence or absence of a lamellar columella and pedicellate vs. transverse division. (Category 1) Flabellum, exemplified by F. magnificum, USNM 81951. (Category 2) Periplacotrochus, exemplified by the holotype of
P.cudmorei.(Category 3) Truncatoflabellum, exemplified by the neotype of T. candeanum, USNM 81963. (Category 4) Placotrochus, exemplified by P. laevis, USNM 81994.
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