Veliger larva of the gastropod, Fusitriton oregonensis by Louise Page Posterior of juvenile kinorhynch, Pycnophyes kielensis by Andreas Schnidt-Rhaesa
Copulatory organs of the acoel, Haplocelis dichona by Matthew Hooge
All images & captions from here
These remarkable images are produced by Confocal Laser Scanning Microscopy and show what amazing detail modern technology can reveal.
The images were presented at a conference called 'The New Microscopy: Novel Characters and the Importance of Morphology in Phylogenetic Analysis'. Several papers from this conference are now avilable from the journal Integrative and Comparative Biology which seems to be open access. Lots of interesting stuff has appeared in that journal, the archives are well worth a browse.
Here are the relavent papers:
Neurogenesis in myriapods and chelicerates and its importance for understanding arthropod relationships
Postembryonic development of dorsoventral and longitudinal musculature in Pycnophyes kielensis (Kinorhyncha, Homalorhagida)
Polychaete nervous systems: Ground pattern and variations--cLS microscopy and the importance of novel characteristics in phylogenetic analysis
Novel methodology utilizing confocal laser scanning microscopy for systematic analysis in arthropods (Insecta)