David A. Grimaldi

Fossiliferous Cretaceous amber from Myanmar (Burma): Its rediscovery, biotic diversity, and paleontological significance

Abstract Amber from Kachin, northern Burma, has been used in China for at least a millennium for carving decorative objects, but the only scientific collection of inclusion fossils, at the Natural History Museum, London (NHML), was made approximately 90 years ago. Age of the material was ambiguous, but probably Cretaceous. Numerous new records and taxa occur in this amber, based on newly excavated material in the American Museum of Natural History (AMNH) containing 3100 organisms. Without having all groups studied, significant new records and taxa thus far include the following (a † refers to extinct taxa): For Plants: An angiosperm flower (only the third in Cretaceous amber), spores and apparent sporangia of an unusual but common fungus, hepatophyte thalli and an archegoniophore of Marchantiaceae, and leafy shoots of Metasequoia (Coniferae). Metasequoia is possibly the source of the amber. For Animals: Mermithidae and other Nematoda; the oldest ixodid tick (a larval Amblyomma); bird feathers; and the only Mesozoic record of the Onychophora (“velvet” worms), described as †Cretoperipatus burmiticus, n. gen., n. sp. (Peripatidae). Poinars classification of the Onychophora is substantially revised. Still largely unstudied, the fauna of mites (Acari) and spiders (Araneae) appears to be the most diverse ones known for the Mesozoic. For Insecta: Odonata indet. (wing fragment); Plecoptera indet.; new genera of Dermaptera, Embiidina, and Zoraptera (the latter two as the only definitive Mesozoic fossils of their orders). Within Hemiptera, there are primitive new genera in the Aradidae, Hydrometridae, Piesmatidae, Schizopteridae, and Cimicomorpha (Heteroptera), as well as in †Tajmyraphididae (Aphidoidea), and †′otopsyllidiidae. An adult snakefly (Raphidioptera: †Mesoraphidiidae) is the smallest species in the order, and new genera occur in the Neuroptera: Coniopterygidae, Berothidae, and Psychopsidae, as well as larvae of apparent Nevrorthidae. Coleoptera are largely unstudied, but are probably the most diverse assemblage known from the Cretaceous, particularly for Staphylinidae. An adult lymexylid, the most primitive species of Atractocerus, is the first Mesozoic record of the family. In Hymenoptera there are primitive ants (Formicidae: Ponerinae n. gen., and †Sphecomyrma n.sp [Sphecomyrminae]), the oldest record of the Pompilidae, and significant new records of †Serphitidae and †Stigmaphronidae, among others. Diptera are the most diverse and abundant, with the oldest definitive Blephariceridae and mosquito (Culicidae), as well as new genera in the Acroceridae, Bibionidae, Empidoidea; a new genus near the enigmatic genus Valeseguya, and an unusual new genus in the †Archizelmiridae. †Chimeromyia (Diptera: Eremoneura), known previously in ambers from the Lower Cretaceous, is also represented. The stratigraphic distribution of exclusively Mesozoic arthropods in Burmese amber is reviewed, which indicates a probable Turonian-Cenomanian age of this material (90–100 Ma). Paleofaunal differences between the NHML and AMNH collections are discussed, as is the distinct tropical nature of the original biota. Burmese amber probably harbors the most diverse biota in amber from the Cretaceous, and one of the most diverse Mesozoic microbiotas now known.

Episodic radiations in the fly tree of life

Flies are one of four superradiations of insects (along with beetles, wasps, and moths) that account for the majority of animal life on Earth. Diptera includes species known for their ubiquity (Musca domestica house fly), their role as pests (Anopheles gambiae malaria mosquito), and their value as model organisms across the biological sciences (Drosophila melanogaster). A resolved phylogeny for flies provides a framework for genomic, developmental, and evolutionary studies by facilitating comparisons across model organisms, yet recent research has suggested that fly relationships have been obscured by multiple episodes of rapid diversification. We provide a phylogenomic estimate of fly relationships based on molecules and morphology from 149 of 157 families, including 30 kb from 14 nuclear loci and complete mitochondrial genomes combined with 371 morphological characters. Multiple analyses show support for traditional groups (Brachycera, Cyclorrhapha, and Schizophora) and corroborate contentious findings, such as the anomalous Deuterophlebiidae as the sister group to all remaining Diptera. Our findings reveal that the closest relatives of the Drosophilidae are highly modified parasites (including the wingless Braulidae) of bees and other insects. Furthermore, we use micro-RNAs to resolve a node with implications for the evolution of embryonic development in Diptera. We demonstrate that flies experienced three episodes of rapid radiation—lower Diptera (220 Ma), lower Brachycera (180 Ma), and Schizophora (65 Ma)—and a number of life history transitions to hematophagy, phytophagy, and parasitism in the history of fly evolution over 260 million y.

New light shed on the oldest insect.

Insects are the most diverse lineage of all life in numbers of species, and ecologically they dominate terrestrial ecosystems. However, how and when this immense radiation of animals originated is unclear. Only a few fossils provide insight into the earliest stages of insect evolution, and among them are specimens in chert from Rhynie, Scotlands Old Red Sandstone (Pragian; about 396–407 million years ago), which is only slightly younger than formations harbouring the earliest terrestrial faunas. The most well-known animal from Rhynie is the springtail Rhyniella praecursor (Entognatha; Collembola), long considered to be the oldest hexapod. For true insects (Ectognatha), the oldest records are two apparent wingless insects from later in the Devonian period of North America. Here we show, however, that a fragmentary fossil from Rhynie, Rhyniognatha hirsti, is not only the earliest true insect but may be relatively derived within basal Ectognatha. In fact, Rhyniognatha has derived characters shared with winged insects, suggesting that the origin of wings may have been earlier than previously believed. Regardless, Rhyniognatha indicates that insects originated in the Silurian period and were members of some of the earliest terrestrial faunas.

Termites (Isoptera): Their Phylogeny, Classification, and Rise to Ecological Dominance

Abstract Like ants, termites are entirely eusocial and have profound ecological significance in the tropics. Following upon recent studies reporting more than a quarter of all known fossil termites, we present the first phylogeny of termite lineages using exemplar Cretaceous, Tertiary, and Recent taxa. Relationships among Recent families were largely unaffected by the addition of extinct taxa, but the analysis revealed extensive grades of stem-group taxa and the divergence of some modern families in the Cretaceous. Rhinotermitidae, Serritermitidae, and the “higher” termites (family Termitidae), which comprise 84% of the world termite species, diverged and radiated entirely in the Tertiary, corresponding to a significant increase in termite individuals in the fossil record. Radiation of the higher termites may have affected the formation of terrestrial carbon reserves like oil and coal. The higher classification of Isoptera is slightly revised based on the phylogenetic results. The following new taxa are proposed: Cratomastotermitidae, new family; Euisoptera, new clade; Archotermopsidae, new family; and Neoisoptera, new clade. In addition, the families Stolotermitidae, Stylotermitidae, and Archeorhinotermitidae are newly recognized or resurrected, and the families Termopsidae and Hodotermitidae are significantly restricted in composition.

Biogeographic and evolutionary implications of a diverse paleobiota in amber from the early Eocene of India

For nearly 100 million years, the India subcontinent drifted from Gondwana until its collision with Asia some 50 Ma, during which time the landmass presumably evolved a highly endemic biota. Recent excavations of rich outcrops of 50–52-million-year-old amber with diverse inclusions from the Cambay Shale of Gujarat, western India address this issue. Cambay amber occurs in lignitic and muddy sediments concentrated by near-shore chenier systems; its chemistry and the anatomy of associated fossil wood indicates a definitive source of Dipterocarpaceae. The amber is very partially polymerized and readily dissolves in organic solvents, thus allowing extraction of whole insects whose cuticle retains microscopic fidelity. Fourteen orders and more than 55 families and 100 species of arthropod inclusions have been discovered thus far, which have affinities to taxa from the Eocene of northern Europe, to the Recent of Australasia, and the Miocene to Recent of tropical America. Thus, India just prior to or immediately following contact shows little biological insularity. A significant diversity of eusocial insects are fossilized, including corbiculate bees, rhinotermitid termites, and modern subfamilies of ants (Formicidae), groups that apparently radiated during the contemporaneous Early Eocene Climatic Optimum or just prior to it during the Paleocene-Eocene Thermal Maximum. Cambay amber preserves a uniquely diverse and early biota of a modern-type of broad-leaf tropical forest, revealing 50 Ma of stasis and change in biological communities of the dipterocarp primary forests that dominate southeastern Asia today.

Competition in Natural Populations of Mycophagous Drosophila

In the northeastern United States, individual mushrooms commonly harbor the larvae of up to four species of Drosophila (D. falleni, D. recens, D. putrida, and D. testacea), as well as larvae of crane flies (Tipulidae), wood gnats (Anisopodidae), and other, small flies. An experiment showed that larvae of these species commonly exhaust the food in single mushrooms under natural conditions. Supplemental mushroom increased survival to adulthood in three Drosophila species and resulted in larger adult flies. There was substantial variation among individual mushrooms in the degree of food depletion by larvae; while some mushrooms were completely devoured, others appeared to provide more than enough food for the larvae. Mean body sizes of Drosophila that matured in nature were similar to those of flies reared in our experiments without supplemental food, which suggests that resource depletion and larval competition are common in natural populations of these species. (While the evidence for resource limitation is compelling, our methods do not allow us to distinguish between intraand interspecific competition.) As a result, fitness of flies in nature should vary greatly as a function of the amount of food available to larvae. We speculate that low rates of parasitism allow mycophagous Drosophila populations to deplete food resources more commonly than do phytophagous insects.

Treatise on the Isoptera of the World

ABSTRACT A comprehensive compendium on the taxonomy and biology of the 3106 living and fossil species of the worlds termites is presented, along with reviews of Isoptera morphology and evolution, identification keys, the history of termite systematics, and summary of the worlds 363 significant pest species. A complete bibliography is provided of nearly 5000 references covering virtually all aspects of termite taxonomy and biology through December 2011. The morphology of Isoptera is thoroughly reviewed and illustrated with original scanning electron micrographs and photomicrographs, covering the cuticular anatomy and those internal organs that are taxonomically and phylogenetically significant, including several new character systems. Terminology is presented for the systems of tibial spines and spurs so as to establish homologs. Keys are presented to the nine living families of termites, and the world subfamilies and genera of Archotermopsidae, Hodotermitidae, Kalotermitidae, Mastotermitidae, Rhinotermiti...

Arthropods in amber from the Triassic Period

The occurrence of arthropods in amber exclusively from the Cretaceous and Cenozoic is widely regarded to be a result of the production and preservation of large amounts of tree resin beginning ca. 130 million years (Ma) ago. Abundant 230 million-year-old amber from the Late Triassic (Carnian) of northeastern Italy has previously yielded myriad microorganisms, but we report here that it also preserves arthropods some 100 Ma older than the earliest prior records in amber. The Triassic specimens are a nematoceran fly (Diptera) and two disparate species of mites, Triasacarus fedelei gen. et sp. nov., and Ampezzoa triassica gen. et sp. nov. These mites are the oldest definitive fossils of a group, the Eriophyoidea, which includes the gall mites and comprises at least 3,500 Recent species, 97% of which feed on angiosperms and represents one of the most specialized lineages of phytophagous arthropods. Antiquity of the gall mites in much their extant form was unexpected, particularly with the Triassic species already having many of their present-day features (such as only two pairs of legs); further, it establishes conifer feeding as an ancestral trait. Feeding by the fossil mites may have contributed to the formation of the amber droplets, but we find that the abundance of amber during the Carnian (ca. 230 Ma) is globally anomalous for the pre-Cretaceous and may, alternatively, be related to paleoclimate. Further recovery of arthropods in Carnian-aged amber is promising and will have profound implications for understanding the evolution of terrestrial members of the most diverse phylum of organisms.

Treatise on the Isoptera of the World: VOLUME 1 INTRODUCTION

ABSTRACT A comprehensive compendium on the taxonomy and biology of the 3106 living and fossil species of the worlds termites is presented, along with reviews of Isoptera morphology and evolution, identification keys, the history of termite systematics, and summary of the worlds 363 significant pest species. A complete bibliography is provided of nearly 5000 references covering virtually all aspects of termite taxonomy and biology through December 2011. The morphology of Isoptera is thoroughly reviewed and illustrated with original scanning electron micrographs and photomicrographs, covering the cuticular anatomy and those internal organs that are taxonomically and phylogenetically significant, including several new character systems. Terminology is presented for the systems of tibial spines and spurs so as to establish homologs. Keys are presented to the nine living families of termites, and the world subfamilies and genera of Archotermopsidae, Hodotermitidae, Kalotermitidae, Mastotermitidae, Rhinotermitidae, Serritermitidae, Stolotermitidae, and Stylotermitidae. A key to subfamilies of the Termitidae is included. A detailed morphological diagnosis for each family and subfamily is provided, along with images of exemplar species. The history of isopteran research in taxonomy, systematics, morphology, paleontology, and biology is reviewed from 1758 to the present, with emphasis on transformative workers such as Holmgren, Silvestri, Emerson, Roonwal, Noirot, and Sands. Evolution of the Isoptera is reviewed, including the diversity and natural history of genera and species in all Zoogeographic regions, major patterns in social biology, the phylogeny of Recent and fossil genera and families, and 135 million years of fossils preserved as compressions, mineralized replicas, and in amber. The definitive sister group to the Isoptera is the monogeneric family of wood roaches, Cryptocercidae (Cryptocercus), so the taxonomic ranks of the two groups are now Infraorder Isoptera and Infraorder Cryptocercoidea within Order Blattaria (roaches and termites). The compendium summarizes the taxonomic history, nomenclature, distribution, type locality, and repository, and all significant aspects of natural history and biology for each species of the world, exclusive of pest control and colony inquilines (termitophiles). The classification of Recent and fossil lower termites (all those exclusive of family Termitidae) used in the compendium is from Engel et al. (2009), which is based on morphology and largely congruent with molecular studies. Rhinotermitidae s.s. (exclusive of Stylotermitidae) may be paraphyletic with respect to Termitidae, although the six traditional subfamilies of the former are used here. A separate section summarizes the nomenclatural changes made in the compendium, including new synonymies, new combinations, status novus, lectotype selection etc. A detailed list is provided of museums and other institutional collections that house type specimens. An index is included. The Treatise is intended to provide an authoritative foundation for taxonomic work on the Isoptera, present and future.

Genetic variation for host preference within and among populations of Drosophila tripunctata

Some time ago, perhaps in the Miocene, a number of flies dispersed from the Old World to the New World tropics, multiplied, and thus initiated the tripunctata radiation of the genus Drosophila (Throckmorton, 1975). The descendant species diversified ecologically, and they now breed variously in fungi, rotting fruits, sap flows, flowers, and decaying vegetation-a diversity of larval feeding niches almost as broad as that of the genus itself. A sole member of this radiation, D. tripunctata, has colonized the Nearctic, and it is presently abundant in many forests of the central and eastern United States (Wheeler, 1981; Fig. 1). This species is polyphagous in an unusual and interesting way: it commonly utilizes both decaying fruits and mushrooms as breeding sites (Sturtevant, 1921; Carson and Stalker, 1951). Since Drosophila larvae are not very vagile, the primary basis for the polyphagy of D. tripunctata and indeed for the ecological diversification of the group as a whole must ultimately reside in the oviposition site preference of female flies. The diversification of descendant species, in particular, would seem to depend critically on the existence of genetic variation for host preference among females. Of course, physiological adaptations that allow larvae to exploit these various resources are also important and should, in general, evolve in concert with changes in oviposition site preference (for examples in