Ancient DNA of the pygmy marmoset type specimen Cebuella pygmaea(Spix,1823)resolves a taxonomic conundrum

The pygmy marmoset,the smallest of the anthropoid primates,has a broad distribution in Western Amazonia.Recent studies using molecular and morphological data have identified two distinct species separated by the Napo and Solimoes-Amazonas rivers.However,reconciling this new biological evidence with current taxonomy,i.e.,two subspecies,Cebuella pygmaea pygmaea(Spix,1823)and Cebuella pygmaea niveiventris(Lönnberg,1940),was problematic given the uncertainty as to whether Spix’s pygmy marmoset(Cebuella pygmaea pygmaea)was collected north or south of the Napo and Solimoes-Amazonas rivers,making it unclear to which of the two newly revealed species the name pygmaea would apply.Here,we present the first molecular data from Spix’s type specimen of Cebuella pygmaea,as well as novel mitochondrial genomes from modern pygmy marmosets sampled near the type locality(Tabatinga)on both sides of the river.With these data,we can confirm the correct names of the two species identified,i.e.,C.pygmaea for animals north of the Napo and Solimoes-Amazonas rivers and C.niveiventris for animals south of these two rivers.Phylogenetic analyses of the novel genetic data placed into the context of cytochrome b gene sequences from across the range of pygmy marmosets further led us to reevaluate the geographical distribution for the two Cebuella species.We dated the split of these two species to 2.54 million years ago.We discuss additional,more recent,subdivisions within each lineage,as well as potential contact zones between the two species in the headwaters of these rivers.

Virtual reality systems for rodents

Over the last decade virtual reality （VR） setups for rodents have been developed and utilized to in-vestigate the neural foundations of behavior. Such VR systems became very popular since theyallow the use of state-of-the-art techniques to measure neural activity in behaving rodents that can-not be easily used with classical behavior setups. Here, we provide an overview of rodent VR tech-nologies and review recent results from related research. We discuss commonalities and differ-ences as well as merits and issues of different approaches. A special focus is given to experimental（behavioral） paradigms in use. Finally we comment on possible use cases that may further exploitthe potential of VR in rodent research and hence inspire future studies.

Secondary neurogenesis and telencephalic organization in zebrafish and mice: a brief review

Most zebrafish neurodevelopmental studies have focused on the embryo,which is characterized by primary neurogenesis of mostly transient neurons.Secondary neurogenesis becomes dominant in the hatching larva,when major brain parts are established and begin to differentiate.This developmental period allows for a comparative analysis of zebrafish brain organization with amniotes at equivalent stages of neurogenesis.Within a particular time window,the early forebrains of mice(Embyronic stage[E]12.5/13.5 days[d])and zebrafish(3 d)reveal highly comparable expression patterns of genes involved in neurogenesis,for example proneural and other transcription factors(Neurogenin1,NeuroD,Mash1/Zash1a and Pax6).Further topological correspondences are seen in the expression of LIM and homeobox genes,such as Lhx6/7,Tbr2 and Dlx2a.When this analysis is extended to gamma-aminobutyric acid/glutamic acid decarboxylase(GABA/GAD)cell patterns during this critical time window,an astonishing degree of similarity between the two species is again seen,for example regarding the presence of GABA/GAD cells in the subpallium,with the pallium only starting to be invaded by such cells from the subpallium.Furthermore,the expression of proneural and other genes correlates with GABA cell patterns(e.g.Mash1/Zash1a gene expression in GABA-positive and Neurogenin1/NeuroD in GABA-negative telencephalic regions)in mice and zebrafish.Data from additional vertebrates,such as Xenopus,are also highly consistent with this analysis.Therefore,the vertebrate forebrain appears to undergo a phylotypic stage of secondary neurogenesis,characterized by regionally separated GABAergic(inhibitory)versus glutamatergic(excitatory)cell production sites,which are obscured later in development by tangential migration.This period is highly advantageous for molecular neuroanatomical cross-species comparisons.

Age and ovarian development are related to worker personality and task allocation in the ant Leptothorax acervorum

In social insects, workers of different morphological castes and age are known to act differently. Yet, it is unclear how body size and ovarian development influence worker personalities （i.e. consistent behavioral variation） and task allocation in similar aged ant workers of monomorphic species. Behavioral variation is thought to be a key element of division of labor, but few studies have linked worker personality to task allocation. We investigated individual behavior in Leptothorax acervorum ant workers at two time points during the first three months of their life and in two different settings. We observed worker behavior in the nest （i.e. task allocation） and in standardized aggression, exploration and brood care experiments （i.e. personality） and found behavioral repeatability in foraging and exploration. Further, workers acted consistently across settings： workers with a more ag gressive and exploratory personality type were more active in the nest. Moreover, ovarian development was associated with worker personality and task allocation： older workers with welldeveloped ovaries foraged less, but were more aggressive and exploratory. In accordance with the typical agepolyethism of social insects, workers became more active and foraged more as they grew older. Consequently, our study suggests that task allocation in Leptothorax acervorum is not only influenced by ovari an development and age, but moreover by the personalities of its workers .

Kinematics of whip spider pedipalps: a 3D comparative morpho-functional approach

Amblypygi are tropical and subtropical ambush predators that use elongated,raptorial pedipalps for different activities.Although pedipalp use in predation and courtship has been explored in videography in vivo analyses,kinematic ex vivo examination of these appendages has not been conducted.Here,we rectify this lack of data by using microCT scans to 3D-kinematically model the appendage morphology and the range of motion(ROM)of the joints for Damon medius and Heterophrynus elaphus.We illustrate the successful application of this technique to terrestrial euarthropods in determining the maximum ROM values for each pedipalp joint.We also note that,in life,these values would be lower due to motion restricting structures like tendons,arthrodial membranes,and muscles.We further compare our maximum values obtained here with data from video-based motion analyses.The ROM of each joint shows the greatest flexibility in the femur-tibia joint(140–150°),the lowest in the basitarsus-claw joint(35–40°).ROM in the tibia-basitarsus joint is markedly distinct(D.medius:44°;H.elaphus:105°).This disparity reflects how H.elaphus uses the joint in the capture basket,while D.medius uses the femur-tibia joint to form the capture basket.We further illustrate notable vertical motion of the H.elaphus pedipalp compared to D.medius.This difference reflects the retro-ventral trochanter apophysis of H.elaphus.Our study opens the possibility to further whip spider kinematic understanding.Examination of other taxa using this approach will result in a more comprehensive understanding of the ecological significance and ethological implications of this unique arachnid group.