|The polystyelid ascidian Distomus hupferi (Michaelsen, 1904) in the northern France, and comments on its European congenerics|
Newberry, A.T. (1995). The polystyelid ascidian Distomus hupferi (Michaelsen, 1904) in the northern France, and comments on its European congenerics. Cah. Biol. Mar. 36(2): 63-68
In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723, more
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The polystyelid ascidian Distomus hupferi, known mainly from northwest Africa, inhabits rocky shores in northern Brittany, along with D. variolosus, more common on laminarian stipes . Specimens show both species around Roscoff in the 1960's; comments by earlier researchers suggest they both were there 80 years ago. Shape and arrangement of the testes differ markedly between these species, and other traits reinforce the distinction made on that basis. The Mediterranean species D. fuscus has testes shaped like those of D. hupferi but arranged like those of D. variolosus, and it has many more longitudinal branchial vessels and more stomach grooves. Hartmeyer's opinion remains convincing that D. fuscus, customarily taken to be a southern form of D. variolosus, is a valid species. The possibility that all three species are actually ecotypes of D. variolosus remains to be explored but currently is unsupported by clear evidence.