A fossil species of Pheidole Westwood, 1839 (Formicidae, Myrmicinae) was described based on an amber inclusion found in the Miocene strata at Chiapas, southwestern Mexico. It was named Pheidole pauchil sp. nov., which is the first described species of the genus in Mexican amber. This broadens our understanding of the diversity of Pheidole in the Miocene in the southernmost part of North America.

Two species of fossil polydesmidan millipedes (Diplopoda: Polydesmida) embedded in amber are described from Miocene strata near Simojovel, in the Chiapas Highlands, Mexico. Maatidesmus paachtun gen. et sp. nov., placed into Chelodesmidae Cook, 1895, and Anbarrhacus adamantis gen. et sp. nov., assigned in the family Platyrhacidae Pocock, 1895. Morphological data from fossil specimens have been recovered using 3D X-ray micro-computed tomography and regular to infrared-reflected microscopy. Both fossil species are recognizable as new primarily but not exclusively, by collum margin modification and remarkable paranotal and metatergite dorsal sculpture.

A new species of scorpion is described based on a rare entire adult male preserved in a cloudy amber from Miocene rocks in the Chiapas Highlands, south of Mexico. The amber-bearing beds in Chiapas constitute a Conservation Lagerstätte with outstanding organic preservation inside plant resin. The new species is diagnosed as having putative characters that largely correspond with the genus Tityus Koch, 1836 (Scorpiones, Buthidae). Accordingly, it is now referred to as Tityus apozonalli sp. nov. Its previously unclear phylogenetic relationship among fossil taxa of the family Buthidae from both Dominican and Mexican amber is also examined herein. Preliminarily results indicate a basal condition of T. apozonalli regarding to Tityus geratus Santiago-Blay and Poinar, 1988, Tityus (Brazilotityus) hartkorni Lourenço, 2009, and Tityus azari Lourenço, 2013 from Dominican amber, as was Tityus (Brazilotityus) knodeli Lourenço, 2014 from Mexican amber. Its close relationships with extant Neotropic Tityus-like subclades such as ‘Tityus clathratus’ and the subgenus Tityus (Archaeotityus) are also discussed. This new taxon adds to the knowledge of New World scorpions from the Miocene that are rarely found trapped in amber.

A new record of fossil moss in Miocene amber from Chiapas, southern Mexico, is hereby presented. The fossil moss is assigned to the genus Hypnodontopsis Iwatsuki et Noguchi (Family Rhachitheciaceae) and characterized primarily by narrowly lanceolate to linear leaves arranged in rosettes, with erect costae, and short apiculate leaf tips, with upper cells larger than the lower cells. This sample, for which current worldwide distribution consists of at least three disjunct and geographically restricted occurrences, represents the first fossil record of the genus Hypnodontopsis in the Americas. While Hypnodontopsis is represented by five fossil species known from Eocene Baltic and Saxon amber, extant species are known from Asia, Africa and Mexico. The new fossil specimen most closely resembles the extant species Hypnodontopsis mexicana (Thér.) H. Robins, synonymous with the fossil species Hypnodontopsis conferta (Goeppert and Berendt) J.-P. Frahm. from Eocene Baltic amber. Hypnodontopsis mexicana ca... Resumen. Se presenta un nuevo registro de musgo fósil en ámbar miocénico de Chiapas, al sur de México. El musgo fósil está asignado al género Hypnodontopsis Iwatsuki et Noguchi (Familia Rhachitheciaceae). El ejemplar se caracteriza por presentar hojas estrechamente lanceoladas a lineares y dispuestas en rosetas, con costas erectas, y con ápices agudos, con células superiores más gruesas que las células inferiores. Este representa el primer registro fósil del género Hypnodontopsis para América, cuya distribución actual consiste en al menos tres ocurrencias separadas y geográficamente restringidas. Hypnodontopsis está representado por cinco especies fósiles de ámbar del Eoceno del Báltico y Sajonia, mientras que las especies actuales se encuentran en Asia, África y México. El nuevo espécimen fósil se asemeja a la especie actual Hypnodontopsis mexicana (Ther.) H. Robins., sinónimo de la especie fósil Hypnodontopsis conferta (Goeppert y Berendt) J.-P. Frahm. en el ámbar del Eoceno del Báltico. Hypnodontopsis ...

The Chiapas Amber-Lagerstätte is a fossil preservation site in southern Mexico, consisting of three central localities: Simojovel, Totolapa, and Estrella de Belén. It is a repository that preserves a diverse range of estuarine-associated biota. These include but are not limited to arboreal, aerial, land-dwelling, soil-based, amphibiotic, aquatic, and microbial organisms. The age and stratigraphy of the amber-bearing beds near Simojovel have been interpreted differently. The amber outcrops were initially considered part of the late Oligocene to Early Miocene La Quinta Formation. Further studies identified several outcrops as part of the Early Miocene Mazantic Shale and the Middle Miocene Balumtum Sandstone. We present the zircon U–Pb dating results conducted on the amber-bearing beds in the uppermost section of the Simojovel Formation. The data indicate a maximum depositional age of 24 ± 1 Ma, corresponding to the uppermost late Oligocene. A limited section of the amber deposit in Totolapa is likely contemporary with the lowermost Early Miocene, ca. 20 Ma. Hence, the amber biota is constrained to the uppermost late Oligocene and the lowermost Early Miocene (ca. 24–20 Ma). Our data also suggest that the sedimentary environment of the upper strata oscillates from estuary to shallow shelf. It is characterized by low-energy zones with a constant influx of terrigenous sediments consisting of siltstone and fine-grained sandstone, with gastropods, bivalves, coral fragments, trace fossils, plant remains, lignite, and amber.

A new fossil species of salticid spider (Araneae: Salticidae) is described based on an amber-embedded specimen. The specimen was collected from lignite-sandstone early-mid Miocene sediments near the town of Totolapa in Chiapas, southwestern Mexico. The diagnosis and description is supported by key characters that best match the genusMaeviaKoch, 1846. Thus, this new fossil species has been namedMaevia eurekanov. sp. This fossil shows closer affinities in epygine traits with extant specimens grouped around the speciesMaevia poultoniPeckham & Peckham, 1901. This represents the first known fossil species withinMaeviaand the southernmost record of the genus in North America that shows Nearctic relationships.