Genome Size Dynamics in Marine Ribbon Worms (Nemertea, Spiralia).

Nemertea is a phylum consisting of 1300 mostly marine species. Nemertea is distinguished by an eversible muscular proboscis, and most of the species are venomous. Genomic resources for this phylum are scarce despite their value in understanding biodiversity. Here, we present genome size estimates of Nemertea based on flow cytometry and their relationship to different morphological and developmental traits. Ancestral genome size estimations were done across the nemertean phylogeny. The results increase the available genome size estimates for Nemertea three-fold. Our analyses show that Nemertea has a narrow genome size range (0.43-3.89 pg) compared to other phyla in Lophotrochozoa. A relationship between genome size and evolutionary rate, developmental modes, and habitat was found. Trait analyses show that the highest evolutionary rate of genome size is found in upper intertidal, viviparous species with direct development. Despite previous findings, body size in nemerteans was not correlated with genome size. A relatively small genome (1.18 pg) is assumed for the most recent common ancestor of all extant nemerteans. The results provide an important basis for future studies in nemertean genomics, which will be instrumental to understanding the evolution of this enigmatic and often neglected phylum.

Holistic description of new deep sea megafauna (Cephalopoda: Cirrata) using a minimally invasive approach.

BACKGROUND: In zoology, species descriptions conventionally rely on invasive morphological techniques, frequently leading to damage of the specimens and thus only a partial understanding of their structural complexity. More recently, non-destructive imaging techniques have successfully been used to describe smaller fauna, but this approach has so far not been applied to identify or describe larger animal species. Here, we present a combination of entirely non-invasive as well as minimally invasive methods that permit taxonomic descriptions of large zoological specimens in a more comprehensive manner. RESULTS: Using the single available representative of an allegedly novel species of deep-sea cephalopod (Mollusca: Cephalopoda), digital photography, standardized external measurements, high-field magnetic resonance imaging, micro-computed tomography, and DNA barcoding were combined to gather all morphological and molecular characters relevant for a full species description. The results show that this specimen belongs to the cirrate octopod (Octopoda: Cirrata) genus Grimpoteuthis Robson, 1932. Based on the number of suckers, position of web nodules, cirrus length, presence of a radula, and various shell characters, the specimen is designated as the holotype of a new species of dumbo octopus, G. imperator sp. nov. The digital nature of the acquired data permits a seamless online deposition of raw as well as derived morphological and molecular datasets in publicly accessible repositories. CONCLUSIONS: Using high-resolution, non-invasive imaging systems intended for the analysis of larger biological objects, all external as well as internal morphological character states relevant for the identification of a new megafaunal species were obtained. Potentially harmful effects on this unique deep-sea cephalopod specimen were avoided by scanning the fixed animal without admixture of a contrast agent. Additional support for the taxonomic placement of the new dumbo octopus species was obtained through DNA barcoding, further underlining the importance of combining morphological and molecular datasets for a holistic description of zoological specimens.

Two new giant pill-millipede species of the genus Zoosphaerium endemic to the Bemanevika area in northern Madagascar (Diplopoda, Sphaerotheriida, Arthrosphaeridae).

Madagascar is one of the world's most important hotspots of biodiversity and a center for localized endemism. Among the highly endemic faunal elements are the giant pill-millipedes, order Sphaerotheriida, which are severely understudied in Madagascar. Here we provide descriptions of two new species of endemic giant-pill millipedes of the genus Zoosphaerium Pocock, 1895: Zoosphaerium bemanevika n. sp. and Zoosphaerium minutus n. sp.. Zoosphaerium bemanevika n. sp. belongs to the Z. coquerelianum species-group, while Z. minutus n. sp. is not assignable to a species-group. An updated key to the 19 species of the Z. coquerelianum group is provided. Zoosphaerium minutus n. sp. has a body length of <20 mm and thus is the smallest known member of the genus, being of similar size as the larger species of Microsphaerotherium Wesener & VandenSpiegel, 2007. Both species are described utilizing drawings, scanning electron microscopy and genetic barcoding based on the mitochondrial COI gene. MicroCT imaging is applied to study internal morphology non-destructively and in situ, allowing for a reconstruction of the head skeleton. Our results show that females of Z. bemanevika n. sp. exhibit island gigantism. The two newly described species are not closely related to one another but each to different species from the Marojejy Mountain and the lowland rainforest of the east coast. Both species occur sympatrically as microendemics in small patches of humid evergreen forest near Bemanevika in northern Madagascar, an only recently protected area that represents a Malagasy center of endemism.

Phylogeographic analyses reveal Transpontic long distance dispersal in land snails belonging to the Caucasotachea atrolabiata complex (Gastropoda: Helicidae).

The phylogeography and population structure of land snails belonging to the Caucasotachea atrolabiata complex in the Caucasus region was investigated to obtain a better understanding of diversification processes in this biodiversity hotspot. So far the complex has been classified into three species, C. atrolabiata from the north-western Caucasus, C. calligera from Transcaucasia and C. intercedens from the eastern Pontus Mountains. Phylogenetic (neighbor-net and neighbor-joining tree) as well as admixture analyses based on AFLP data showed that the complex consists of two population clusters corresponding to C. atrolabiata and C. calligera. The populations assigned to C. intercedens in fact represent hybrids consisting of different proportions of the genomes of C. atrolabiata and C. calligera. There is a broad transition zone between C. atrolabiata and C. calligera in the Pontic Mountains and a second transition zone in Abkhazia. Because of evidence for gene flow, it is suggested to classify the two aforementioned taxa as subspecies, namely C. a. atrolabiata and C. a. calligera. The presence of mitochondrial C. a. atrolabiata haplotypes in Turkey can only be explained by passive dispersal across the Black Sea. The distribution of C. a. atrolabiata and additional cases of land snails with disjunct Transpontic distribution patterns cannot be ascribed to a common cause but are results of long distance dispersal events at different times.