Showing papers by "Rolf G. Beutel published in 2017"

Head morphology of the smallest beetles (Coleoptera: Ptiliidae) and the evolution of sporophagy within Staphyliniformia)

Abstract: Ptiliidae include the smallest known beetles. External and internal head structures of species with different body sizes and feeding prefer­ ences were examined and described in detail. Saprophagous and sporophagous species are compared. The observed features are evaluated with respect to their phylogenetic and functional significance, and their correlation with extreme size reduction. A putative autapomorphy of Staphyliniformia is an unusual extrinsic maxillary muscle, which among ptiliids is only present in the saprophagous species. Synapo­ morphies of Ptiliidae and their sister group Hydraenidae are a lateral mandibular process forming a unique locking device with a lateral groove of the labrum, and mandibles divided into a main body and a mesal molar part, both connected by a membrane. Extreme body size reduction is a presumptive autapomorphy of Ptiliidae that probably resulted in the following derived features: the loss of cephalic sutures and ridges, a simplified tentorium, and a brain modified in shape and very large in relation to the head size. The ptiliid species with sap­ rophagous and sporophagous feeding habits show only subtle differences in their cephalic structures, notably in details of the epipharynx and galeae and in the configuration of maxillary muscles. Two alternative scenarios are suggested for the evolution of feeding habits, based on the morphological results and presently available information on phylogenetic relationships. One option is to assign saprophagy to the groundplan of the family, with two switches to sporophagy; first in the basal Nossidium and then a second time in the extremely small Na­ nosellini, which are characterized by feeding habits that we address as microsporophagy. An alternative scenario is that feeding on spores is ancestral for Ptiliidae, with reversals to saprophagy in several branches of the family, and a specialization on very small spores in the strongly miniaturized nanoselline species. A well-founded species level phylogeny of Ptiliidae with a dense taxon sampling will help to clarify this issue.

The head of the earwig Forficula auricularia (Dermaptera) and its evolutionary implications

Abstract: The external and internal head morphology including the musculature of the common earwig Forficula auricularia is described in detail. We specified and corrected previous descriptions and provided a detailed documentation. The head of Forficula is characterized by prognathism, generalized mandibles with a mesal cutting edge distally of the mola and its drop-shaped appearance. We added the following new apomorphies for Dermaptera to the various previously reported ones: (I) coronal and frontal cleavage lines with corresponding strong internal strengthening ridges; (II) the division of the praementum into a basal and a distal sclerite; (III) the presence of a bumpulus at the tip of the paraglossa; (IV) the presence of large distal palpilla on the terminal maxillary and labial palpomeres and (V) the origin of M. tentoriohypopharyngealis on the submentum. Another potential apomorphy are the lateral lobes on the distal hypopharynx which are most likely not homologous to the superlingua of apterygote insect. Other characters such as the prominent ball-and-socket joint between scapus and pedicellus or the unique antennal heart are poorly studied within Dermaptera and therefore cannot be phylogenetically polarized. In contrast to the various ordinarial apomorphies, the dermapteran head exhibits only one potential synapomorphy with other polyneopteran orders: the absence of the linguactual tendon and the associated muscle that is shared with Plecoptera and/or Zoraptera. Our results show that additional studies of the presumingly basal splits of Dermaptera are required to understand the head evolution of the group.

Ademosynidae (Insecta: Coleoptera): A new concept for a coleopteran key taxon and its phylogenetic affinities to the extant suborders

Abstract: †Ademosynidae is a controversial extinct family of Coleoptera, first discovered in Australian Upper-Triassic deposits. The last known representative is known from the Early Jurassic of Kirghizstan. Type material from the collection of Moscow Paleontological Institute is re-described here and interpreted phylogenetically. The results show that the family as presently defined is not monophyletic, but possibly divided among two of four extant coleopteran suborders. We establish a new narrower concept of the family including the genera Ademosyne Handlirsch, 1906, Dolichosyne Ponomarenko, 1969, Gnathosyne Ponomarenko, 1969, Cephalosyne Ponomarenko, 1969, Petrosyne Ponomarenko, 1969, and Sphaerosyne Ponomarenko, 1969. This monophyletic unit is characterized by two synapomorphies of the prothorax, the absence of anterolateral pronotal angles and a rounded protruding anterior pronotal margin covering the posterior part of the head. Additional characters are large mandibles distinctly protruding anteriorly, striated elytra, an indistinct pronoto-elytral angle resulting in a stream-lined body, and a cuticular surface with coarse punctures. Based on the lack of the two prothoracic apomorphies, the Permian Archosyne Ponomarenko et al., 2014 is excluded from the family. As its placement remains very uncertain, it should be treated as Coleoptera incertae sedis. Ranis Ponomarenko, 1968 also lacks the pronotal features defining †Ademosynidae. Based on the internalized propleuron it is transferred to the megadiverse suborder Polyphaga. In its evolutionary history in the Mesozoic, †Ademosynidae reflects a general trend in Coleoptera, an increasing reinforcement of the configuration of the thoracic sclerites. Evgeny V. Yan. Institut für Spezielle Zoologie und Evolutionsbiologie, Friedrich Schiller University Jena, 07737, Germany and Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya str. 123, Moscow, 117997 Russia. yan-e@mail.ru Rolf G. Beutel. Institut für Spezielle Zoologie und Evolutionsbiologie, Friedrich Schiller University Jena, 07737, Germany. rolf.beutel@uni-jena.de Alexander G. Ponomarenko. Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya str. 123, Moscow, 117997 Russia. aponom@paleo.ru

The NOVA project: maximizing beam time efficiency through synergistic analyses of SRμCT data

Abstract: Beamtime and resulting SRμCT data are a valuable resource for researchers of a broad scientific community in life sciences. Most research groups, however, are only interested in a specific organ and use only a fraction of their data. The rest of the data usually remains untapped. By using a new collaborative approach, the NOVA project (Network for Online Visualization and synergistic Analysis of tomographic data) aims to demonstrate, that more efficient use of the valuable beam time is possible by coordinated research on different organ systems. The biological partners in the project cover different scientific aspects and thus serve as model community for the collaborative approach. As proof of principle, different aspects of insect head morphology will be investigated (e.g., biomechanics of the mouthparts, and neurobiology with the topology of sensory areas). This effort is accomplished by development of advanced analysis tools for the ever-increasing quantity of tomographic datasets. In the preceding project ASTOR, we already successfully demonstrated considerable progress in semi-automatic segmentation and classification of internal structures. Further improvement of these methods is essential for an efficient use of beam time and will be refined in the current NOVAproject. Significant enhancements are also planned at PETRA III beamline p05 to provide all possible contrast modalities in x-ray imaging optimized to biological samples, on the reconstruction algorithms, and the tools for subsequent analyses and management of the data. All improvements made on key technologies within this project will in the long-term be equally beneficial for all users of tomography instrumentations.