02162nas a2200169 4500008004100000022001400041245014200055210006900197260000800266490000600274520154100280100002101821700002201842700002801864700001701892856008301909 2019 eng d a2056-306X00aComparative morphology of ultimate and walking legs in the centipede Lithobius forficatus (Myriapoda) with functional implications0 aComparative morphology of ultimate and walking legs in the centi cdec0 v53 a

Background: In the context of evolutionary arthopodial transformations, centipede ultimate legs exhibit a plethora of morphological modifications and behavioral adaptations. Many species possess significantly elongated, thickened, or pincer-like ultimate legs. They are frequently sexually dimorphic, indicating a role in courtship and mating. In addition, glandular pores occur more commonly on ultimate legs than on walking legs, indicating a role in secretion, chemical communication, or predator avoidance. In this framework, this study characterizes the evolutionarily transformed ultimate legs in Lithobius forficatus in comparison with regular walking legs. Results: A comparative analysis using macro-photography, SEM, μCT, autofluorescence, backfilling, and 3Dreconstruction illustrates that ultimate legs largely resemble walking legs, but also feature a series of distinctions. Substantial differences are found with regard to aspects of the configuration of specific podomeres, musculature, abundance of epidermal glands, typology and distribution of epidermal sensilla, and architecture of associated nervous system structures. Conclusion: In consideration of morphological and behavioral characteristics, ultimate legs in L. forficatus primarily serve a defensive, but also a sensory function. Moreover, morphologically coherent characteristics in the organization of the ultimate leg versus the antenna-associated neuromere point to constructional constraints in the evolution of primary processing neuropils.

1 aKenning, Matthes1 aSchendel, Vanessa1 aMüller, Carsten, H. G.1 aSombke, Andy uhttps://zoologicalletters.biomedcentral.com/articles/10.1186/s40851-018-0115-x01664nas a2200241 4500008004100000022001400041245012500055210006900180300000600249490000600255520092900261653000801190653001501198653001401213653001601227653001801243653001901261653001601280653000801296100001701304700001901321856008201340 2017 eng d a2056-306X00aSerotonergic neurons in the ventral nerve cord of Chilopoda - a mandibulate pattern of individually identifiable neurons0 aSerotonergic neurons in the ventral nerve cord of Chilopoda a ma a90 v33 a

Given the numerous hypotheses concerning arthropod phylogeny, independent data are needed to supplement knowledge based on traditional external morphology and modern molecular sequence information. One promising approach involves comparisons of the structure and development of the nervous system. Along these lines, the morphology of serotonin-immunoreactive neurons in the ventral nerve cord has been investigated in numerous tetraconate taxa (Crustacea and Hexapoda). It has been shown that these neurons can be identified individually due to their comparably low number, characteristic soma position, and neurite morphology, thus making it possible to establish homologies at the single cell level. Within Chilopoda (centipedes), detailed analyses of major branching patterns of serotonin-immunoreactive neurons are missing, but are crucial for developing meaningful conclusions on the homology of single cells.

10a5HT10aArthropoda10aEvolution10aMandibulata10aMiracrustacea10aNeurophylogeny10aTetraconata10aVNC1 aSombke, Andy1 aStemme, Torben uhttp://zoologicalletters.biomedcentral.com/articles/10.1186/s40851-017-0070-y