Francisco Riquelme

A fossil stemmiulid millipede (Diplopoda: Stemmiulida) from the Miocene amber of Simojovel, Chiapas, México

A fossil millipede representative of the order Stemmiulida is described on the basis of a well-preserved adult female trapped in amber from the Miocene of Simojovel, Chiapas, south-eastern México. The fossil specimen is named as Parastemmiulus elektron, a new genus and species. As observed in extant stemmiulids, this fossil shows a reduced number of ocelli, the distal larger than the proximal, as well as a total of 46 trunk segments including 2 apodous segments in front of the telson. The head of this ancient stemmiulid has three ocelli and a Tömösváry organ, characteristics not reported before in Stemmiulida, requiring the diagnosis of the order to be emended.http://zoobank.org/urn:lsid:zoobank.org:pub:361400A8-37D4-421F-B4FD-A0AE63BE538C

Two Flat-Backed Polydesmidan Millipedes from the Miocene Chiapas-Amber Lagerstätte, Mexico

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.

FIRST FOSSIL RECORD OF HYPNODONTOPSIS (BRYOPSIDA: RHACHITHECIACEAE) FROM THE AMERICAS

Abstract. 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 can only be found in central Mexico (America) and in Uganda (Africa). Accordingly, the distribution of current and extinct species of Hypnodontopsis suggests that the genus diversified in both Laurasia and Gondwana and then suffered extinction by the end of the Paleogene in Europe.

The millipedes and centipedes of Chiapas amber

An inventory of fossil millipedes (class Diplopoda) and centipedes (class Chilopoda) from Miocene Chiapas amber, Mexico, is presented, with the inclusion of new records. For Diplopoda, 34 members are enumerated, for which 31 are described as new fossil records of the orders Siphonophorida Newport, 1844, Spirobolida Bollman, 1893, Polydesmida Leach, 1895, Stemmiulida Pocock, 1894, and the superorder Juliformia Attems, 1926. For Chilopoda 8 fossils are listed, for which 3 are new records of the order Geophilomorpha Pocock, 1895 and 2 are of the order Scolopendromorpha Pocock, 1895.