Heartless and primitive? 3D reconstruction of the polar acochlidian gastropod Asperspina murmanica

• Published in: Acta Zoologica
• Main Authors: Neusser, Timea P., Martynov, Alexander V., Schrödl, Michael
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2009
• Subjects: Arctic
• Online Access: http://dx.doi.org/10.1111/j.1463-6395.2008.00342.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1463-6395.2008.00342.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1463-6395.2008.00342.x

Abstract This study re‐examines in detail the microanatomy of the Arctic opisthobranch Asperspina murmanica , the only acochlidian that was described as retaining a well‐developed mantle cavity, and evaluates its supposedly basal position within the Acochlidia. Several specimens were recollected at the type locality in Russia. Spicules and radulae were studied by scanning electron microscopy. Semithin sections were prepared and a computer‐based three‐dimensional reconstruction of all major organ systems was made using amira software. Our results show significant differences from the original description, e.g. the nervous system shows paired rhinophoral and gastro‐oesophageal ganglia and large aggregations of precerebral accessory ganglia, whereas the presence of a postulated posterior genital ganglion can be excluded; the radula is asymmetric; the circulatory system includes a small heart; and the reproductive system comprises a sac‐like ampulla and three female glands. The most surprising discrepancy to the original description refers to the complete absence of any mantle cavity. The gonopore, anus and nephropore open separately to the exterior. Instead of being aberrant or basal, A. murmanica fits well with other Asperspina species and comes closest to the Mediterranean Asperspina rhopalotecta . The monotypic genus/family Minicheviella /Minicheviellidae Starobogatov (1983 ) is confirmed as a junior synonym of Asperspina /Asperspinidae Rankin (1979 ).