| Author Title Journal |
Lender T (1935) Sur Polycelis nigra (Ehrbg.) et Polycelis tenuis (Ijima)Turbellaries Triclades. Arch Zool exp 78 Notes et revue(2):49-56 |
Abstract / Notes
The writer compares Polycelis nigra and P. tenuis and concludes that they are distinct species although commonly found together in nature. However, he discredits most of characters described as differential. They cannot be distinguished on external characteristics and the variation and intergradations of the size and shape of the head are stressed. The number of eyespots and the pigmentation are seen as varying with age and light conditions rather than with species. The size and shape of the penis (short and broad in P. nigra and long and narrow in P. tenuis) and the presence of 2 musclo-glandular organs associated with the penis in P. tenuis and absent in P. nigra are seen as the only 2 constant differences between these species
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