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FLOWER A OF SWIETENIA (MELIACEAE) MID-TERTIARY FOSSIL DOMINICAN AMBER IN George 0. Poinar, Jr. Journal of the Botanical Research Institute of Texas 6(1) 124 on (C6pek 45-30 mybp, based coccoliths in proposal being Schlee has proven be controversial, the oldest to & MacPhee 20-15 mybp, based on foraminifera (Iturralde-Vinent 1996). The and youngest being 1999) the Mamey Lower Miocene Upper Eocene Group sandstones of the to amber principally deposited in turbiditic is (Draper etal. 1994). & Swietenia dominicensis K.L. Chambers Poinar, sp. nov. (Figjs. 1-3). Type: HISPANIOLA. Dominican Republic: amber number mine in the northern mountain range (Cordillera Septentrional), 1995, unknown amber miner s.n. (holotype: catalogue Sd- Oregon deposited in the Poinar amber collection maintained at Oregon State University, Corvallis, 97331, U.S.A.). 9-7, mm, apex of filament tube appendages) 3.85 calyx shal- Flower putatively staminate, total length (pedicel to tip mm mm mm fused portion 0.54 long, lobes 0.45 long, broadly rounded, lowly cupulate (Fig. ca. 1.0 long, 2), mm mm spreading, margins ciliolate, petals free, ca. 4.5 long, 2.2 at widest part, spreading or reflexed, some- 5, what contorted, elliptic to oblanceolate, obtuse, glabrous (including margins), filament tube urceolate (Fig. 1), mm mm mm glabrous, 2.9 long excluding appendages, 2.9 wide, appendages 10, deltoid-acuminate, ca. 0.8 mm few long, slighdy spreading, anthers 10, sessile, alternating with appendages, ca. 0.6 long (only a visible for from measurement), dehisced, hypothesized to be fertile, pistil present, ovary not visible, style exserted fila- mm densely minutely ment tube, barely exceeding appendages, stigma enlarged, disc-shaped, 1.3 in diameter, marked 5-6 segments pitted, obscurely into fused (Fig. 3). — From Dominican Etymology. the amber’s source in the Republic. We hypothesize that the flower staminate in function, although anthers are dehisced and are not well is its enough displayed to be sure that pollen was produced. The flower’s overall shape, including the position and mahagoni pub- morphology of the stigma, matches well the excellent drawings of staminate flowers of Swietenia We modem and by compared with humilis lished Miller (1990, 478). also illustrations of the other species, S. p. it macrophylla, in Styles (1981) and with the description and photographs of the Mexican fossil species, S. mio- S. cenica, in Castaiieda-Posadas and Cevallos-Ferriz (2007). Together with the examination of herbarium material of mahagoni, these references support our judgment that the Dominican best placed in Swietenia. S. fossil is modem As noted by Styles (1981) and other authors Helgason et 1996), the 3 species of the genus (e.g. al. mor- are “poorly defined biologically,” are largely allopatric at the present time, and are “reasonably distinct phologically” (Styles 1981). Putative hybrids, from the natural zones of contact in Costa Rica and Guatemala involving S. humilis and S. macrophylla, are intermediate for both ecological tolerance and morphological char- & An such and (Whitmore extensive acters as rachis length leaflet size Hinojosa 1977; Helgason et al. 1996). & polyploid series of chromosome numbers is reported for the genus (Khosla Styles 1975; Helgason et al. A 1996). further complication is that S. mahagoni, in particular, has been widely planted outside its original range in southern Florida and the larger Caribbean islands, thereby increasing the occurrences of species sym- patry. The key we on combina- distinction that relied to separate the present fossil from all other species is its tion of a ciliolate calyx with glabrous-margined mahagoni having glabrous ca- petals. Swietenia described as is lyx lobes and petals, while the other 2 species under discussion have and calyx (Styles 1981)- petals ciliolate remark Miller’s (1990, p. 479) that “this distinction was not apparent in numerous specimens that I studied’ . . . by is offset his statement, perhaps in error, that the calyx and corolla are in mahagoni and smooth- ciliolate S. margined in the other 2 species. Nonetheless, the differences in perianth pubescence described by Styles (of* have held cit.) true in practice (Pennington, pers. obs.). Castafleda-Posadas and Dominican Cevallos-Ferriz (2007) differentiated Swietenia miocenica from this which fossil, they saw of illustrated, but not described, in Poinar and Poinar by differences in the shape (1999), the filament tube and In petals. addition, they described miocenica as having calyx composed of five S. “a free rounded lobes which would . . . ..,’’ differentiate it from all other known species of the genus. To their species we characterization have added the lack of petal mioceni- ciliolation in dominicensis versus presence in S. S. its The ca. age of S. miocenica given by appn*i' these authors mybp (Late OUgocene-Early Miocene, 26.0-22.3 ) and Chambers Poinar, / = m bubbles. Scale bar 1.5 iir Journal of the Botanical Research Institute of Texas 6(1) 126 we separate mates that of dominicensis. Nonetheless, conclude that S. dominicensis is best described as a S. and especially given the different provenance and the morphological details of calyx, filament tube, species, j pubescence. perianth by Muellner et Swietenia placed in the monophyletic subfamily Cedreloideae (formerly Swietenioideae) is j al (2003, 2006). However, compared with the tribe Cedreleae, composed of Cedrela and Tdona (Muellner et al. the remaining tribes Swietenieae and Xylocarpeae, as described by Pennington and Styles (1975), 2009), separate monophyletic (Muellner 2003, 2006). Capuronianthus had been as a not et al. previously classified (Muellner et subfamily by Pennington and Styles (1975), but was later shown to be nested within Cedreloideae by usings 2003). According to Muellner et al. (2003), “some genera and most tribes can only be diagnosed al. j A recon- combination of several characters.” well resolved and sufficiently supported molecular phylogenetic DNA more struction including all genera of Cedreloideae (compare Muellner et 2011 for a recent test of al. and will ul- markers in Cedrela, Swietenia, other genera), along with a detailed morphological re-investigation, new and timately lead to a robust tribal classification within Cedreloideae. Muellner et al. (2006) discussed the fossil history of Meliaceae as a whole, with later reviews, in & ha# detail, for tribe Cedreleae (Muellner et al. 2009, 2010; Pennington Muellner 2010). Fossils of Cedreleae New been reported from the Eocene and later periods, at both northern and the Old and mid-latitude in sites West Gondwanan proposing diS' Worlds. In a origin authors for family Meliaceae (Muellner 2006), the et al. an Eur- cussed “out-of-Africa” scenario, “with between dispersal. important and ..[via] routes across Eurasia . asia and North America provided by Beringia and the North Atlantic land and between North AmerK* bridge, and South America through island chains and/or A Swietenia** direct land connections.” crown group age for ) . . and Chambers Poinar, / not yet been proposed. Based on fossil evidence (Europe, North America) and relaxed molecular clock dating, & crown Cedreleae are believed to date back at least to the Early Eocene (Muellner et 2010; Pennington al. Muellner 2010). The Late Oligocene-Early Miocene age of our and that of Castaneda-Posadas and Ceval- fossil los-Ferriz (2007) verifies the Mid-Tertiary occurrence of Swietenia in Central and South America. ACKNOWLEDGMENTS We New thank the herbaria of Harvard University and The York Botanical for their loan of specimens used in this study. 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