A Lotus from the Early Cretaceous Crato Formation of northeastern Brazil, and its implications for the origin of the group.

Angiosperms, or Flowering Plants, are the most numerous and diverse Plant group today, dominating almost all terestrial environments. The ealiest Angiosperm fossils appear an the Early Cretaceous, around the shores of the Tethys Ocean, with many Angiosperm groups appearing sudenly, in forms apparently not much different to today, making it impossible to tell how these groups are related without molecular data.

Lotuses, Nelumbonaceae, are aquatic Plants, superficially similar to Water Lilies, to which they were once thought to be related. They grow annually from submerged rhizomatous roots, producing large flar leaves with hydrophobic coatings which lie flat upon the water surface. Surprisingly, molecular analysis of Angiosperm relationships has revealed that Lotuses not closely related to Water Lilies, which are related to Magnolias, but instead are members of the Order Proteales (Proteas), most closely related to Plane Trees. This is particularly surprising as all other members of the Proteales are woody shrubs and trees, while Lotuses are aquatic annual herbs lacking any woody tissue. 

In a paper published in ths journal Scientific Reports on 2 June 2023, William Vieira Gobo of the Departamento de Paleontologia e Estratigrafa at the Universidade Federal do Rio Grande do Sul,  Lutz Kunzmann of the Abteilung Museum für Mineralogie und Geologie, Roberto Iannuzzi and Thamiris Barbosa dos Santos, also of the Departamento de Paleontologia e Estratigrafa at the Universidade Federal do Rio Grande do Sul, Domingas Maria da Conceição of the Museu dePaleontologia Plácido Cidade Nuvens at the Universidade Regional do Cariri, Daniel Rodrigues do Nascimento and Wellington Ferreira da Silva Filho of the Departamento de Geologia at the Universidade Federal do Ceará, Julien Bachelier and Clément Coifard of the Structural and Functional PlantDiversity Group at the Freie Universität Berlin, describe a new species of Lotus from the Early Cretaceous Crato Formation of Ceará State, Brazil.

The new species is described from pits to the southwest of Nova Olinda in the Araripe Basin of northeastern Brazil, and now in the collections of the Museum für Naturkunde in Berlin and the Senckenberg Forschungsinstitut und Naturmuseum in Frankfurt am Main. The authors acknowledge that there are currently unresolved issues concerning fossils from the Crato deposits, with the Brizilian government regarding all removal of the fossils from the country as illegal, and asking that collections in other parts of the world return them, but note that the Brazilian members of the team were invited by the German institutions to come and study the material. The Plant is named Notocyamus hydrophobus, where 'Notocyamus' means 'Southern Bean' in Greek, a refernce to the term 'Egyptian Bean' used by Teophrastos of Eresos to refer to Lotus seeds, and 'hydrophobus' refers to the hydrophobic leaves of Lotus Plants.

Notocyamus hydrophobus (holotype, MB. Pb. 2002/1047). (A) Overview of the whole plant, with roots, rhizome, leaves, and aggregate fruit in organic connection. A black arrow points to the part of the peduncle used to make the thin sections. (B) Details of higher-order venation. (C) Close-up of palinactinodromous venation and the marginal lamina attachment. (D) Close-up on the enlarged receptacle showing two globose fruitlets (presumed nutlets). Scale bars are 1 cm. Gobo et al. (2023).

The holotype specimen is about 30 cm high and about 25 cm wide, and comprises a rhizome with about 30 roots, 13 leaves, and a single fruiting body. Leaves are 60 to 95 cm long and 60 to 100 mm wide, and oval to eliptical in shape. They are attached to petiole stems 120-200 mm long and 5-10 mm wide. The cells of the leaves are discernable, larger on the upper side than on the lower with each cell bearing a single papilla (hair), agian larger above than below.

Notocyamus hydrophobus (paratype, SMF SM.B 16.522). (A) Isolated leaf. (B), (C) Close-ups of the pattern of venation. Note that abundant structures interpreted as galls occur along the lamina and petiole (arrows point to some of them). Scale bars are 5 mm. Gobo et al. (2023).

The fruiting body is borne on a peduncle stem 22.5 cm long and 4 mm wide. Notably, this peduncle has in inner pith layer surrounded by xylem (wood), a tissue not seen in any modern Lotus, but present in all other members of the Order Proteales. 

Notocyamus hydrophobus (holotype, MB. Pb. 2002/1047). (A)–(B) Transversal section of the peduncle. (A) Overview displaying homoxylic wood with abundant fbers interspersed with parenchymatous rays. Te dashed outline shows the rays connecting with primary xylem that form bundles near the pith. On the periphery, remains of the cambial zone occur in a discontinuous layer that is followed by new vascular increments. (B) Close-up of region near pith showing the primary xylem bundles and their connection with the rays. Abbreviations: pi. pith; px, primary xylem; sx, secondary xylem; r, ray; cz, cambial zone; vi, vascular increments; pxb, primary xylem bundles. Scale bars: (A) 1 mm; (B) 250 µm. Gobo et al. (2023).

The xylum tissue comprises an inner layer of 18 (or possibly 19) primary bundles, surrounded by a secondary homoxylic (vesselless) layer. No growth rings are present, and the whole is surrounded by an ounter layer thought to be the remains of the cambium (bark).

Notocyamus hydrophobus (holotype, MB. Pb. 2002/1047). Radial (A)–(G) and tangential (H) sections of the peduncle. (A) Overview of region adjacent to the pith (to the far right) showing vessels in the xylem followed by the secondary xylem with ray and fber cells (to the far left). (B) Primary xylem cells with helical thickenings and fbers of secondary xylem. (C) A vessel element with scalariform-like pits and simple perforation plates (arrows). (D) Close-up of a fiber showing simple (black arrow) and slit-like pits (white arrow). (E) Ray cells with slit-like pit apertures. (F) Overview of region near cambial zone (dashed outline) showing fber and ray cells in the secondary xylem followed by the layer that gives rise to the new vascular increments. (G) Fusiform and compressed cells from the cambial zone followed by tracheary elements with scalariform-like pits. (H) Ray cells in between fbers of secondary xylem. Abbreviations: v, vessels; px, primary xylem; r, ray; f, fber; cz, cambial zone; vi, vascular increments. Scale bars: (A), (F) 200 µm; (B), (C), (E), (G) 50 µm; (D) 25 µm; (H) 100 µm. Gobo et al. (2023).

The Crato Formation has not been dated precisely, but is thought to be slightly more than 120 million years old, which, if correct, would make Notocyamus hydrophobus the oldest known member of the Nelumbonaceae. Molecular dating techniques have suggested that the Nelumbonaceae branched from theit closest relatives, the Platanaceae (Plane Trees) between 83 and 123 million years ago. Since dates at the younger end of this range can be ruled out by other, more modern-looking fossil Lotuses it is not unreasonable to assume that the group dates from the earlier part of this bracket, or possibly a little older. Either way, the assumption that Notocyamus hydrophobus is a very early member of the group, still showing some similarities to non-Lotus relatives, is not unreasonable.

Reconstruction of Notocyamus hydrophobus in its likely environment. Rebecca Dart in Gobo et al. (2023).

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Tylototriton umphangensis: A new species of Crocodile Newt from Tak Province, western Thailand.

Crocodile Newts, Tylototriton spp., range from the eastern Himalayas eastward into central and southern China, and south into Southeast Asia. These Newts are terrestrial outside their breeding season, and have a very narrow range of environmental tolerances, occupying moist subtropical forests at medium-to-high elevations, where the temperature ranges from 15−24.0°C and rainfall is high year-round. Breeding typically occurs during the Monsoon Season. 

The most southerly members of the group are found in Thailand, where there are currently considered to be five species, Tylototriton verrucosus, Tylototriton uyenoi, Tylototriton anguliceps, Tylototriton phukhaensis, and Tylototriton panhai. A number of new populations of these Newts have been discovered in recent years, in the Daen Lao, Thanon Thong Chai, and Dawna mountain ranges. All of these have been provisionally assigned to Tylototriton uyenoi, but this is thought unlikely to be correct, as they show some variation and are scattered in mountainous areas in which both lowlands and mountain ridges are likely to present barriers to distribution.

One of these new populations lies within the Umphang Wildlife Sanctuary in Tak Province, and appears to be both physically and genetically distinct from other Tylototriton species. In a paper published in the journal ZooKeys on 19 November 2021, Porrawee Pomchote and Parada Peerachidacho of the Department of Biology at Chulalongkorn University, Axel Hernandez of the Department of Environmental Sciences at the University Pasquale Paoli of Corsica and the Laboratory for Amphibian Systematic and Evolutionary Research at Nanjing Forestry University, Pitak Sapewisut of the Department of Biology at Chiang Mai University, Wichase Khonsue and Panupong Thammachoti again of the Department of Biology at Chulalongkorn University, and Kanto Nishikawa of the graduate schools of Global Environmental Studies and Human and Environmental Studies at Kyoto University, formally describe this Tak Province population as a new species.

The new species description is based upon four male specimens that were collected during a field survey by Porrawee Pomchote and Pitak Sapewisut on 19 June 2021, and subsequently determined to be a new species upon the basis of both morphological and genetic analysis. The new species is named Tylototriton umphangensis, where 'umphangensis' means 'from Umphang'. 

 

A specimen of Tylototriton umphangensis in the wild. Pomchote et al. (2021).

Like all Crocodile Newts, Tylototriton umphangensis has granular nodules on its dorsal surface, as we;; as bony ridges on its head and along its spine. It is a medium-sized member of the genus, with a length ranging from 65.6-75.3 mm excluding the tail (Newts can regrow their tails, so the length of a Newt's tail is not considered useful for assessing its size). They have short snouts, bulging quadrate regions, prominent head and spine ridges, and narrow tails. They are dark brown to blackish in colour, with the underside being lighter than the upper.

All four specimens were collected from under leaf litter and among the stems of Arrowroot Plants in a small ephemeral pond in an evergreen forest, during the local rainy season. The pond was 5.2 m long and 2.7 m wide, and 17 cm deep at its deepest. The area lies within the Dawna Mountain Range, which extends from eastern Myanmar into northwestern Thailand, and the species is thought likely to occur elsewhere within this range. 

 

Habitat at the type locality of Tylototriton umphangensis at Umphang Wildlife Sanctuary, Tak Province, western Thailand. Pomchote et al. (2021).

A second population of similar Newts has been reported from an artificial pond near the Mae Klong Khi Forest Ranger Station, but when Pomchote et al. visited this site on the evening of 18 June 2021, they found that Fish had been introduced to this pond, Cattle were roaming freely in the area, and construction work was ongoing, all of which would point to this site being lost to the Newts. Cattle and Human settlements are also encroaching on other natural environments in the area, including national parks, leading Pomchote et al. to conclude that Tylototriton umphangensis should be classified as Endangered under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species.

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