Frank Hünefeld

Morphological and molecular evidence converge upon a robust phylogeny of the megadiverse Holometabola

We present the largest morphological character set ever compiled for Holometabola. This was made possible through an optimized acquisition of data. Based on our analyses and recently published hypotheses based on molecular data, we discuss higher‐level phylogeny and evolutionary changes. We comment on the information content of different character systems and discuss the role of morphology in the age of phylogenomics. Microcomputer tomography in combination with other techniques proved highly efficient for acquiring and documenting morphological data. Detailed anatomical information (356 characters) is now available for 30 representatives of all holometabolan orders. A combination of traditional and novel techniques complemented each other and rapidly provided reliable data. In addition, our approach facilitates documenting the anatomy of model organisms. Our results show little congruence with studies based on rRNA, but confirm most clades retrieved in a recent study based on nuclear genes: Holometabola excluding Hymenoptera, Coleopterida (= Strepsiptera + Coleoptera), Neuropterida excl. Neuroptera, and Mecoptera. Mecopterida (= Antliophora + Amphiesmenoptera) was retrieved only in Bayesian analyses. All orders except Megaloptera are monophyletic. Problems in the analyses are caused by taxa with numerous autapomorphies and/or inapplicable character states due to the loss of major structures (such as wings). Different factors have contributed to the evolutionary success of various holometabolan lineages. It is likely that good flying performance, the ability to occupy different habitats as larvae and adults, parasitism, liquid feeding, and co‐evolution with flowering plants have played important roles. We argue that even in the “age of phylogenomics”, comparative morphology will still play a vital role. In addition, morphology is essential for reconstructing major evolutionary transformations at the phenotypic level, for testing evolutionary scenarios, and for placing fossil taxa.
© The Willi Hennig Society 2010.

The evolutionary history of holometabolous insects inferred from transcriptome-based phylogeny and comprehensive morphological data

BackgroundDespite considerable progress in systematics, a comprehensive scenario of the evolution of phenotypic characters in the mega-diverse Holometabola based on a solid phylogenetic hypothesis was still missing. We addressed this issue by de novo sequencing transcriptome libraries of representatives of all orders of holometabolan insects (13 species in total) and by using a previously published extensive morphological dataset. We tested competing phylogenetic hypotheses by analyzing various specifically designed sets of amino acid sequence data, using maximum likelihood (ML) based tree inference and Four-cluster Likelihood Mapping (FcLM). By maximum parsimony-based mapping of the morphological data on the phylogenetic relationships we traced evolutionary transformations at the phenotypic level and reconstructed the groundplan of Holometabola and of selected subgroups.ResultsIn our analysis of the amino acid sequence data of 1,343 single-copy orthologous genes, Hymenoptera are placed as sister group to all remaining holometabolan orders, i.e., to a clade Aparaglossata, comprising two monophyletic subunits Mecopterida (Amphiesmenoptera + Antliophora) and Neuropteroidea (Neuropterida + Coleopterida). The monophyly of Coleopterida (Coleoptera and Strepsiptera) remains ambiguous in the analyses of the transcriptome data, but appears likely based on the morphological data. Highly supported relationships within Neuropterida and Antliophora are Raphidioptera + (Neuroptera + monophyletic Megaloptera), and Diptera + (Siphonaptera + Mecoptera). ML tree inference and FcLM yielded largely congruent results. However, FcLM, which was applied here for the first time to large phylogenomic supermatrices, displayed additional signal in the datasets that was not identified in the ML trees.ConclusionsOur phylogenetic results imply that an orthognathous larva belongs to the groundplan of Holometabola, with compound eyes and well-developed thoracic legs, externally feeding on plants or fungi. Ancestral larvae of Aparaglossata were prognathous, equipped with single larval eyes (stemmata), and possibly agile and predacious. Ancestral holometabolan adults likely resembled in their morphology the groundplan of adult neopteran insects. Within Aparaglossata, the adult’s flight apparatus and ovipositor underwent strong modifications. We show that the combination of well-resolved phylogenies obtained by phylogenomic analyses and well-documented extensive morphological datasets is an appropriate basis for reconstructing complex morphological transformations and for the inference of evolutionary histories.

The genital morphology of Zorotypus hubbardi Caudell, 1918 (Insecta: Zoraptera: Zorotypidae)

The internal and external genitalia of both sexes of Zorotypus hubbardi Caudell 1918 were examined. A detailed description is provided, especially for the male genitalia. The results were compared with the conditions in potentially related neopteran groups. Most features of the internal genitalia of both sexes are plesiomorphic. Putative autapomorphies are: fusion of the distal parts of the vasa deferentia, division of the ductus ejaculatorius (de) into two sections by a distinct circular furrow, dorso-median processes on tergites VIII–X, an asymmetric aedoeagus with a cryptic slit-like phallotrema, reduction of the right outer paramere, the specific asymmetric shape of the endophallus with three conspicuous pouches, the endophallic sclerites scl1–scl6 and their specific arrangement, the specific arrangement of the endophallic muscularis and the unpaired genital muscles m2, m4, m5, m6 and m7. These features cannot be regarded as autapomorphies of the whole order Zoraptera with reliability, as the morphology of the external male genitalia seems to be highly variable within the genus Zorotypus and the intra-generic relationships are poorly resolved. Potential synapomorphies were found with several neopteran groups under comparison: with Embiidina a strengthened muscularis surrounding the de, reduction of the ovipositor and a shortened tergite IX, with Psocoptera the occurance of dense sperm bundles and with Hemiptera a strengthened muscularis of the de. No synapomorphies were found with Dictyoptera. Homologies of the muscles m1 and m3 found in Z. hubbardi with some genital muscles in Dictyoptera and Psocoptera are highly ambiguous.

Neotropical Eois (Lepidoptera: Geometridae): Checklist, Biogeography, Diversity, and Description Patterns

ABSTRACT The moth genus Eois Hübner (Lepidoptera: Geometridae: Larentiinae) comprises 254 validly described species, 211 of them (83%) occurring in the Neotropical region, 12% in the Asian-Australian region, and 5% in Africa. A checklist of Neotropical Eois is provided and some taxonomic changes are made. Aplogompha noctilaria (Schaus) is excluded from the genus, and Eois bermellada (Dognin) and Eois fragilis (Warren) are transferred to the genus. Further changes include Eois cellulata (Prout) stat. rev., Eois ambarilla (Dognin) stat. rev., and Eois telegraphica Prout stat. rev. By far, the majority of Eois species (82%) were described between 1891 and 1920; approximately half of all species by just two authors. Within the Neotropical region, the majority of species (55%) were described from the tropical Andes (Colombia, Ecuador, Peru, and Bolivia), followed by Central America and the Caribbean (28%), and the rest of South America (17%). Large regions such as the Amazon basin, eastern South America, but also northern Peru are heavily underrepresented. Regional diversity studies provide evidence that the wet tropical Andes are the diversity hotspot of Eois. From a forested elevational gradient (1,020–2,670 m above sea level) in southeastern Ecuador, 154 morphospecies are currently known, with only ≈12% of them described. Regional species richness in Central America is lower (Costa Rica, 66 observed morphospecies along a gradient from 40 to 2,730 m; ≈29% described). Total richness of the genus is estimated to be >1,000 species in the Neotropical region. R the low proportions of described species only partly recur in other groups of Neotropical geometrid moths, their number may exceed 19,000 species. A taxonomic revision of Eois will be a prerequisite for comparison of ecological data from different regions.

The skeletomuscular system of the larva of Drosophila melanogaster (Drosophilidae, Diptera): a contribution to the morphology of a model organism.

The morphological features of the third instar larva of the most important insect model, Drosophila melanogaster, are documented for the first time using a broad spectrum of modern morphological techniques. External structures of the body wall, the cephaloskeleton, and the musculature are described and illustrated. Additional information about other internal organs is provided. The systematic implications of the findings are discussed briefly. Internal apomorphic features of Brachycera and Cyclorrhapha are confirmed for Drosophila. Despite the intensive investigations of the phylogeny of the megadiverse Diptera, evolutionary reconstructions are still impeded by the scarcity of anatomical data for brachyceran larvae. The available morphological information for the life stages of three insect model organisms -D. melanogaster (Diptera, Drosophilidae), Manduca sexta (Lepidoptera, Sphingidae) and Tribolium castaneum (Coleoptera, Tenebrionidae) - is addressed briefly. The usefulness of a combination of traditional and innovative techniques for an optimized acquisition of anatomical data for different life stages is highlighted.

A simple "hands-off" apparatus to inflate concealed soft parts of the genitalia of small insect specimens.

We describe a simple, effective and relatively cheap instrument for the inflation of soft parts of insect genitalia, particularly the vesica (endophallus) of small male lepidopteran specimens. It can also be applied in female genitalia and for the hyperextension of postabdominal segments of the telescoping type. A fine glass capillary is mounted on a self‐constructed micromanipulator system with capillary holder, moveably placed aside a microscope. The micromanipulator is constructed from the x‐ and y‐pinions of a discarded microscope table and the z‐pinion of a discarded microscope. Preparation is carried out as usual on a microscopic slide. The inflatable soft parts are pushed out mechanically and then fully inflated and subsequently hardened by pumping absolute alcohol with a medical syringe via a flexible PVC tube, the capillary holder and the glass capillary into the phallus. With affordable effort, our “hands‐off”apparatus might considerably ease preparation. Microsc. Res. Tech. 76:258–262, 2013.

The evolution of "deformed" brains in ant-like stone beetles (Scydmaeninae, Staphylinidae).

We present the first study of the central nervous system of adult representatives of Scydmaeninae. Histological staining, scanning electron microscopy and computer-based 3D reconstruction techniques were used to document the shape and configuration of the major cephalic elements of the central nervous system and to explain its anomalies compared to other Coleoptera. For the first time we report the presence of cephalic glands in ant-like stone beetles: in Scydmaenus (Cholerus) hellwigii openings of voluminous glands are located near the occipital constriction and their secretion accumulates in a large cavity of the dorsal head region. In Scydmaenus (Cholerus) perrisi the proto-, deuto-, tritocerebrum and the suboesophageal ganglion together form a large and compact ganglionic mass around the anterior foregut in the retracted neck region of the head. We exclude miniaturization as the driving force of the observed modifications. Comparative study of the head anatomy of S. perrisi, S. hellwigii, Scydmaenus (s. str.) tarsatus, Scydmaenus (Parallomicrus) rufus and Neuraphes elongatulus suggests a possible evolutionary scenario. We propose an evolutionary reversal hypothesis, involving a) the displacement and concentration of the cephalic central nervous system induced by the development of glandular cavities of the head, followed by b) a reduction of the glandular structures, without a secondary relocation of the cephalic CNS. The interpretation of head modifications in Scydmaeninae in the light of such a scenario may turn out as important for the reconstruction of the phylogeny and evolution of this highly successful group of beetles.