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Wednesday, May 18th, 2022
| Time | Event | ||||||
| 7:09a | [Crustacea • 2022] Thailandorchestia rhizophila • A New Genus and Species of Driftwood Hopper (Amphipoda: Protorchestiidae) from Thailand
Abstract During a scientific survey, a new genus of driftwood hopper was found in mangrove roots in Ko Kut District, Trat Province, Thailand. We placed this new genus, Thailandorchestia gen. nov., within the family Protorchestiidae. The new genus can be distinguished from the remaining genera by uropod 1 outer ramus with robust setae, uropod 2 outer ramus without robust setae, and pereopod 7 basis without a posterodistal lobe. The type species of Thailandorchestia gen. nov., Thailandorchestia rhizophila sp. nov., is described herein, and an updated key to the genera of the family Protorchestiidae is provided. Keywords: Description, Ko Kut District, marsh hopper, Talitroidea, Thailandorchestia gen. nov.
Systematics Order Amphipoda Latreille, 1816 Suborder Senticaudata Lowry & Myers, 2013 Family Protorchestiidae Myers & Lowry, 2020 Genus Thailandorchestia gen. nov. Diagnosis: Protorchestiidae with maxilliped palp article 2 distomedial lobe absent. Mandible left lacinia mobilis 4-dentate. Gnathopod 2 coxal gill simple. Pereopod 4 carpus significantly shorter than carpus of pereopod 3. Pereopods 6–7 sexually dimorphic (male merus and carpus incrassate). Pereopod 7 posterodistal lobe absent. Uropod 1 peduncle distolateral robust setae present, very large (1/3–1/2 length of outer ramus); inner ramus linear, not modified; outer ramus with marginal robust setae. Uropod 2 outer ramus without marginal robust setae. Uropod 3 peduncle with 2 robust setae; ramus shorter than peduncle, linear (narrowing). Telson apically incised, with 2 robust setae per lobe. Etymology: The generic name, Thailandorchestia gen. nov., is derived from “Thailand” in combination with the Orchestia stem. Type locality: Mangrove forest near Ban Ao Prao Beach (11°35'40.2"N, 102°33'52.6"E), Trat Province, Thailand. Ecological type: Driftwood hoppers (virtually confined to rotting driftwood where they live in galleries, consuming rotting driftwood and reproducing with relatively small broods). Thailandorchestia rhizophila sp. nov. Diagnosis: As for the genus unless otherwise stated. Antenna 1 long, reaching from midpoint to end of article 5 of antenna 2 peduncle. Eye medium (1/5–1/3 of head length). Gnathopod 1 not sexually dimorphic, palm transverse, dactylus shorter than palm. Gnathopod 2 sexually dimorphic (male subchelate, female mitten-shaped). Pleopod 1 outer ramus subequal in length to peduncle. Pleopod 3 outer ramus longer than peduncle. Ecology: Driftwood hoppers, living inside rotten logs and mangrove roots in the softest part under the bark. The mangrove forest is located near a small creek 50 meters from the beach. The sediment in the forest is muddy sand mixed with leaf litter. Etymology: The specific epithet refers to the habitat of this amphipod, which is also found inside mangrove roots. Habitat: Mangrove wood, inside roots and rotting logs. Distribution: Thailand, Ko Kut District, Inner Gulf of Thailand. Koraon Wongkamhaeng, Pongrat Dumrongrojwattana, Ratchaneewarn Sumitrakij and Tosaphol Saetung Keetapithchayakul. 2022. Thailandorchestia rhizophila sp. nov., A New Genus and Species of Driftwood Hopper (Crustacea, Amphipoda, Protorchestiidae) from Thailand. ZooKeys. 1099: 139-153. DOI: 10.3897/zookeys.1099.82949 | ||||||
| 8:53a | [Herpetology • 2022] Varanus citrinus • Between A Rock and A Dry Place: Phylogenomics, Biogeography, and Systematics of Ridge-tailed Monitors (Varanidae: Varanus acanthurus complex)
Highlights • We used single nucleotide polymorphisms mitochondrial sequences, and morphological data to infer the evolutionary history of ridge-tailed monitor lizards. • We identified nine populations which we propose belong to four species. • The geographic distribution of the populations and admixture patterns reflect the aridification of Australia and highlight the importance of rocky escarpments as mesic refugia. • We identified and described a new species from a region that has been recognized as a historical refugium in northern Australia. Abstract Genomic data are a powerful tool for the elucidation of evolutionary patterns at the population level and above. The combined analysis of genomic and morphological data can result in species delimitation hypotheses that reflect evolutionary history better than traditional taxonomy or any individual source of evidence. Here, we used thousands of single nucleotide polymorphisms, mitochondrial sequences, and comprehensive morphological data to characterize the evolutionary history of the ridge-tailed monitors in the Varanus acanthurus complex (V. acanthurus, V. baritji, and V. storri), a group of saxicolous lizards with a wide distribution in Australia, the driest vegetated continent. We found substantial genetic structure in the group and identify nine geographically clustered populations. Based on admixture patterns and species delimitation analyses we propose a taxonomic scheme that differs from current taxonomy. We consider V. acanthurus as monotypic, synonymize V. baritji with V. a. insulanicus (as a redefined V. insulanicus), elevate the subspecies of V. storri to full species (V. storri and V. ocreatus), and describe a new species from a previously identified center of endemism. The relationships among the species remain unresolved, likely as a result of fast speciation. Our study highlights the capability of large datasets to illuminate admixture patterns, biogeographic history, and species limits, even when phylogeny is not completely resolved. Furthermore, our results highlight the impact that the Cenozoic aridification of Australia had on saxicolous taxa and the role of mesic rocky escarpments as refugia. These habitats apparently allowed the persistence of lineages that became sources of colonization for arid environments. Keywords: Aridification, Australia, morphometrics, phylogeography, refugia, species delimitation
Varanus citrinus sp. n. Etymology. The Latin specific epithet is treated as an adjective. Citrinus means “related to lemon trees”, and refers to the bright yellow throats of males of the new species. We propose the common names “Gulf Ridge-tailed Monitor” or “Gulf Ridge-tailed Goanna”. Carlos J. Pavón-Vázquez, Damien Esquerré, Alison J. Fitch, Brad Maryan, Paul Doughty, Stephen C. Donnellan and J. Scott Keogh. 2022. Between A Rock and A Dry Place: Phylogenomics, Biogeography, and Systematics of Ridge-tailed Monitors (Squamata: Varanidae: Varanus acanthurus complex). Molecular Phylogenetics and Evolution. In Press, 107516. DOI: 10.1016/j.ympev.2022.107516 twitter.com/NicholasWuNZ/status/1526468712739377152 | ||||||
| 11:16a | [Paleontology • 2022] Sacacosuchus cordovai • Miocene Fossils from the southeastern Pacific shed light on the last Radiation of Marine Crocodylians
Abstract The evolution of crocodylians as sea dwellers remains obscure because living representatives are basically freshwater inhabitants and fossil evidence lacks crucial aspects about crocodylian occupation of marine ecosystems. New fossils from marine deposits of Peru reveal that crocodylians were habitual coastal residents of the southeastern Pacific (SEP) for approximately 14 million years within the Miocene (ca 19 to 5 Ma), an epoch including the highest global peak of marine crocodylian diversity. The assemblage of the SEP comprised two long and slender-snouted (longirostrine) taxa of the Gavialidae: the giant Piscogavialis and a new early diverging species, Sacacosuchus cordovai. Although living gavialids (Gavialis and Tomistoma) are freshwater forms, this remarkable fossil record and a suite of evolutionary morphological analyses reveal that the whole evolution of marine crocodylians pertained to the gavialids and their stem relatives (Gavialoidea). This adaptive radiation produced two longirostrine ecomorphs with dissimilar trophic roles in seawaters and involved multiple transmarine dispersals to South America and most landmasses. Marine gavialoids were shallow sea dwellers, and their Cenozoic diversification was influenced by the availability of coastal habitats. Soon after the richness peak of the Miocene, gavialoid crocodylians disappeared from the sea, probably as part of the marine megafauna extinction of the Pliocene. Keywords: Gavialoidea, longirostrine ecomorphs, biogeography, phylogenetics, marine crocodylians
 Crocodyliformes Hay, 1930 Crocodylia Gmelin, 1789 Longirostres (Cuvier, 1807) Gavialidae (Adams, 1854) Sacacosuchus cordovai gen. et sp. nov. Etymology: Sacaco after the rich fossiliferous area from where most remains were found; cordovai after colleague and Prof. Jesús Córdova, to honour his brave and unconditional support to develop palaeontology in Peru.   Rodolfo Salas-Gismondi, Diana Ochoa, Stephane Jouve, Pedro E. Romero, Jorge Cardich, Alexander Perez, Thomas DeVries, Patrice Baby, Mario Urbina and Matthieu Carré. 2022. Miocene Fossils from the southeastern Pacific shed light on the last Radiation of Marine Crocodylians. Proc. R. Soc. B. 289: 20220380. DOI: 10.1098/rspb.2022.0380 |
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