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Heterosiphonia japonica

( NYN:Japansk sjølyng, japansk straumgarn BOK:Japansk sjølyng, japansk strømgarn)                  11 photos (see below for more photos)


12 cm specimen in February
Photo by: Vivian Husa
Location: Raunefjorden, Hordaland
Photo is showing (categorized): Thallus
Verified by Bergen Seaweed Group
Sampling date: 2006-02-10
Published: 2007-11-22

“Heterosiphonia japonica” is an alien species with Pacific origin (Korea, Japan), first observed in Skårsundet near Bergen in 1996. The species was first called Dasysiphonia sp. when arriving in Europe, and the taxonomic status is still unclear. H. japonica is presently distributed along European coast from Italy in the Mediterranean Sea to the northwest coast of southern Norway. In Norway it thrives in a wide range of habitats, except at very wave exposed shores.




Branching
Photo by: Vivian Husa
Location:
Photo is showing (categorized): Branching pattern
Verified by Bergen Seaweed Group
Sampling date: 2006-02-07
Published: 2007-11-22

Polysiphonous axes with sympodial growth carrying short monosiphonous pseudolateral (short branclets with determinate growth).




In some specimens the peraxial cells are spirally arranged
Photo by: Vivian Husa
Location: Raunefjorden, Hordaland
Photo is showing (categorized): Branching pattern
Verified by Bergen Seaweed Group
Sampling date: 2005-08-22
Published: 2007-11-22





Apices showing uncorticated monosiphonous (one cell row) pseudolaterals.
Photo by: Vivian Husa
Location: Raunefjorden, Hordaland
Photo is showing (categorized): Apical tip
Verified by Bergen Seaweed Group
Sampling date: 2006-02-10
Published: 2007-11-22





Axis with four peraxial cells carrying pseudolaterals from each segment.
Photo by: Vivian Husa
Location: Raunefjorden, Hordaland
Photo is showing (categorized): Branching pattern
Verified by Bergen Seaweed Group
Sampling date: 2006-02-10
Published: 2007-11-22

Sometimes the pseudolaterals can be reduced to a 1-3 celled remain of aborted branches (vegetative reproduction).




Monosiphonous basal cell of pseudolateral
Photo by: Vivian Husa
Location: Raunefjorden, Hordaland
Photo is showing (categorized): Cells
Verified by Bergen Seaweed Group
Sampling date: 2006-02-10
Published: 2007-11-22

The species can be distinguished from Heterosiphonia plumosa by the number of peraxial cells (4 in H. japonica versus 9-10 in H. plumosa). H. plumosa is carrying side branches or pseudolaterals from each second or third segment of the axis, while H. japonica is carrying pseudolaterals from each segment. Additionally the thallus of H. plumosa is arranged in a more complanate way than H. japonica.




Left: Cortication in middle part of branches. Right: Dense cortication at basal parts of branches
Photo by: Vivian Husa
Location: Raunefjorden, Hordaland
Photo is showing (categorized): Cortical cells
Verified by Bergen Seaweed Group
Sampling date: 2005-08-22
Published: 2007-11-22

While distal part of the thallus is uncorticated showing 4 peraxial cells, cortication is increasing towards the basal parts.




Cross section of axis showing axial cell surrounded by four axial cells and smaller medullar cell
Photo by: Vivian Husa
Location: Raunefjorden, Hordaland
Photo is showing (categorized): Cross section
Verified by Bergen Seaweed Group
Sampling date: 2005-08-22
Published: 2007-11-22

At basis of old branches the medullar cells sometimes are so large that they might be mistaken for peraxial cells. These cells are called pseudo-peraxial cells by Barbara (2003).




Tetrasporangial stichidia
Photo by: Vivian Husa
Location: Raunefjorden, Hordaland
Photo is showing (categorized): Tetrasporangium, Reproductive structure
Verified by Bergen Seaweed Group
Sampling date: 2005-08-22
Published: 2007-11-22

At the Norwegian coast the tetrasporophytes are fertile in the period from May to October.




Cystocarp, specimen from northern Spain
Photo by: Vivian Husa
Location: Rio Arusa, Northern Spain
Photo is showing (categorized): Cystocarp, Reproductive structure
Verified by Viviana Peña
Sampling date: 2004-08-22
Published: 2007-11-22

Fertile gametophytes have rarely been observed in the European populations. A few fertile gametophytes (both male and female) were found in the Netherlands in May 2004 (Herre Stegenga, pers. comm), and fertile female specimens have been observed in northern Spain several years during the summer (Viviana Peña pers. comm.). Photo: Viviana Peña




Cystocarps on female specimens from northern Spain
Photo by: Vivian Husa
Location: Rio Arusa, Northern Spain
Photo is showing (categorized): Cystocarp, Reproductive structure
Verified by Viviana Peña
Sampling date: 2004-08-22
Published: 2007-11-22

Photo: Viviana Peña



 

     

     

     

     

     

     

     

     

     

     

     

     

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