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Tuesday, April 2nd, 2024
| Time | Event | ||||||
| 10:38a | [PaleoMammalogy • 2024] Fucaia humilis • The Oldest mysticete (Mysticeti: Aetiocetidae) in the Northern Hemisphere
Highlights: • A new fossil mysticete is described from Washington State, USA • This fossil represents the oldest known mysticete from the Northern Hemisphere • The small body size contrasts with larger coeval whales in the Southern Hemisphere • The coastal kelp ecosystem likely fostered the diversification of early whales Summary Extant baleen whales (Mysticeti) uniquely use keratinous baleen for filter-feeding and lack dentition, but the fossil record clearly shows that “toothed” baleen whales first appeared in the Late Eocene.1 Globally, only two Eocene mysticetes have been found, and both are from the Southern Hemisphere: Mystacodon selenensis from Peru, 36.4 mega-annum (Ma) ago and Llanocetus denticrenatus from Antarctica, 34.2 Ma ago. Based on a partial skull from the lower part of the Lincoln Creek Formation in Washington State, USA, we describe the Northern Hemisphere’s geochronologically earliest mysticete, Fucaia humilis sp. nov. Geology, biostratigraphy, and magnetostratigraphy places Fucaia humilis sp. nov. in the latest Eocene (ca. 34.5 Ma ago, near the Eocene/Oligocene transition at 33.9 Ma ago), approximately coeval with the oldest record of fossil kelps, also in the northeastern Pacific.5 This observation leads to our hypothesis that the origin and development of a relatively stable, nutrient-rich kelp ecosystem5,6 in the latest Eocene may have fostered the radiation of small-sized toothed mysticetes (Family Aetiocetidae) in the North Pacific basin, a stark contrast to the larger Llanocetidae (whether Mystacodon belongs to llanocetids or another independent clade remains unresolved) with the latest Eocene onset of the Antarctic Circumpolar Current in the Southern Hemisphere.7,8,9 Our discovery suggests that disparate mechanisms and ecological scenarios may have nurtured contrasting early mysticete evolutionary histories in the Northern and Southern hemispheres.   Systematics Cetacea Mysticeti Aetiocetidae Fucaia humilis sp. nov. Diagnosis: Fucaia humilis sp. nov. shares with other species of Fucaia a newly identified synapomorphy: a shallow and rounded secondary squamosal fossa on the posterolateral margin of the squamosal (Figure 1). Eomysticetids possess a similar character, but the homology within Mysticeti remains uncertain. Furthermore, Fucaia humilis sp. nov. differs from all other aetiocetids and other Fucaia species by having the following unique character combination: a shorter intertemporal constriction exposed on the skull vertex; the presence of a distinct nuchal tubercle at the junction of parieto-squamosal suture and supraoccipital; a broadly rounded, dorsally low, and lobate coronoid process of the mandible; the presence of a postcoronoid elevation; and rounded anterior border of the tympanic bulla. Etymology: In Latin, humilis refers to humble in English, alluding to the previously unknown humble early mysticete evolution in the Northern Hemisphere.  Cheng-Hsiu Tsai, James L. Goedert and Robert W. Boessenecker. 2024. The Oldest mysticete in the Northern Hemisphere. DOI: 10.1016/j.cub.2024.03.011  | ||||||
| 2:47p | [Botany • 2024] Begonia tanauanensis (Begoniaceae, sect. Baryandra) • A New Species from Batangas Province, Luzon Island, Philippines
Abstract Begonia tanauanensis is a newly described endemic species in B. sect. Baryandra from Tanauan City, Batangas, southern Luzon, Philippines. Morphological data shows this species resembles B. chingipengii, a species from eastern Luzon as both species have light pink flowers, fleshy green lamina, and boat-shaped bracts. However, B. tanauanensis does not have the prominent white midrib and veins in the adaxial leaf surface, ciliate hairs on leaf margin, strongly keeled stipules and tomentose hairs on the abaxial leaf surface and petioles of B. chingipengii. The plants were observed to have a restricted and severely fragmented distribution. Unfortunately, these observed populations are also affected by human activities and threat of volcanic activity of the nearby Taal Volcano. Because of these threats, we provisionally assess the species as “Critically Endangered” (CR) following the IUCN Red List Categories and Criteria. Key words: archipelago, Critically Endangered, Taal Volcano, Tanauan City, Eudicots
Begonia tanauanensis Tandang, Bucay & K.F.Chung, sp. nov. § Baryandra Diagnosis:—Among the tallest of the currently described Philippine Baryandra species in its section, B. tanauanensis has the closest vegetative and reproductive structures to B. chingipengii from Gabaldon, Nueva Ecija in Eastern Luzon by having broad ovate leaves, boat-shaped bracts and light pink flowers. However, B. tananuanensis’s stipules have no keels, or sometimes partly keeled (versus strongly keeled in B. chingipengii), solid green adaxial leaf surface (versus dark green with prominently white midrib and veins of B. chingipengii), setose abaxial leaf surface and petioles (versus tomentose), and glabrous leaf margins (versus ciliated leaf margins). Other key differences are summarized in Table 1. Etymology:—The specific epithet “tanauanensis” is named after the place of its origin, Tanauan City, Batangas in southern Luzon, Philippines.  Mark Angelo C. Bucay, Danilo N. Tandang, Rosario R. Rubite, Edison Jallores Jr. and Kuo-Fang Chung. 2024. A New Begonia Species (sect. Baryandra, Begoniaceae) from Batangas Province, Luzon Island, Philippines. Phytotaxa. 641(4); 277-285. DOI: 10.11646/phytotaxa.641.4.4 |
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