DNA barcoding reveals cryptic diversity in the peanut worm Sipunculus nudus

Peanut worm (Sipunculus nudus) is a cosmopolitan species mainly distributed in tropical and subtropical coastal waters. Analysis of the mitochondrial cytochrome c oxidase subunit I (COI) gene sequences among S. nudus from GenBank revealed high genetic variation (p‐distance, 0.115–0.235; k2p, 0.128–0.297) and paraphyletic relationships. These indicated misidentification and/or cryptic diversity may be present in the genus Sipunculus. To understand the genetic diversity and to manage the recourse of S. nudus, we collected specimens from coastal waters of southern China and Taiwan. In the phylogenetic topology, specimens can be separated into four distinct clades; three of these clades (clade A, B and C) were only represented from this region (southern China and Taiwan), but the clade D grouped with individuals from Central America (Atlantic coast). Furthermore, individuals of clades A and D were collected at the same location, which does not support the hypothesis that this genetic break reflects contemporary geographical isolation. The four distinct clades observed among coastal waters of southern China and Taiwan indicated underestimated diversity. It is noteworthy that the cryptic diversity is vulnerable under high pressure of human activity.     

Zur Ultrastruktur der Blutzellen wirbelloser Tiere

Zusammenfassung In der Haemolymphe von Golfingia gouldi kommen drei Zelltypen vor: Prohaemocyten verschiedener Reife, Erythrocyten und Leukocyten. Die Prohaemocyten entstehen aus proliferierten Peritonealzellen und tragen in frühen Stadien noch Kinocilien. Die Mehrheit ihrer Mitochondrien liegt unmittelbar an der äußeren Kernmembran. Die Ultrastruktur der Erythrocyten ähnelt jener der roten Blutzellen niederer Wirbeltiere. Mitochondrien, endoplasmatisches Retikulum und Golgi-Apparat sind zurückgebildet oder fehlen. Häufig kommen siderosomenähnliche Komplexe im Cytoplasma vor. Die Zellmembran ist deutlich dreischichtig und dicker als gewöhnlich. An ihrer Innenseite sind elektronendichte Körnchen aufgereiht. Die Funktion der Erythrocyten als Sauerstoffspeicher wird diskutiert. Die Leukocyten enthalten elektronendichte Granula, multivesicular bodies, und sind sehr variabel in der Form.

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Studies on the ultrastructure of invertebrate hemocytesII. On the hemocytes of Golfingia gouldi (Sipunculidae)

Summary In the hemolymph of Golfingia gouldi occur three types of cells: Prohemocytes, erythrocytes and leucocytes. The prohemocytes spring from proliferating peritoneal cells and possess cilia at an early stage of their development. The majority of the mitochondria have their outer membrane in direct contact with the outer nuclear membrane. The ultrastructure of erythrocytes is similar to that of lower vertebrates. The mitochondria, endoplasmic reticulum and Golgi-complex are degenerated. Often one finds clusters of a ferritin-like substance. The cell membrane is definitely three-layered. On its inner side there are electron-opaque particles aligned in a row. The function of erythrocytes in oxygen storage is discussed. The leucocytes contain electron-opaque granules surrounded by a membrane and multivesicular bodies and are highly variable in their shape.

Herrn Prof. Dr. med. J. Staubesand danke ich für wertvolle Hinweise und Kritik.