[Annelida] determination of Metasychis and Chirimia species

Geoff Read g.read at niwa.co.nz
Mon Feb 27 15:22:39 EST 2006

Hi Barbara,

Metasychis was erected by Light (1991) in a short but interesting paper from 
the 2nd Polychaete Conference book (Ophelia supplement 5). Metasychis is an 
Asychis-like genus differing in having the ventral cephalic rim (Light's 
cephalic lobes) with cirri-like processes.  A collar on chaetiger one may be 
present or much reduced.  In Chirimia the rim is merely crenulated (saw-like 
notches) and there is a well-developed collar on chaetiger one. I am not 
absolutely sure Light's generic divisions will stand the test of time, but it 
is a while since I examined the details carefully. He doesn't give a key. I 
don't know of any taxonomy done subsequent to Light. M. gotoi is purportedly 
introduced to the Mediterranean. It was first described from Sagami Bay, 
Japan.  As you may be indicating the cephalic rim in the A biceps fig in 
Fauvel looks rather like that in A. gotoi. In Arwidsson's monograph the fig of 
A. biceps shows the cephalic rim as merely crenulated. 

Light, W. J. H. 1991: Systematic revision of the genera of the polychaete 
subfamily Maldaninae Arwidsson. In M. E. Petersen ; J. B. Kirkegaard (ed.) 
Ophelia, Suppl. 5. Systematics, biology and morphology of world Polychaeta; 
2nd International Polychaete Conference, Copenhagen, Denmark, August 18-23, 
1986. 723. Helsingor, Denmark. Illus. Maps. Ophelia Publications. p. 133-146.  

> I need advices for the determination of Metasychis gotoi (Izuka, 1902) 
> and Chirimia biceps (M. Sars, 1861) species.
> I'm working on the soft bottom Polychaeta community in the north 
> Adriatic Sea (Croatia).
> In the former lists of Polychaeta species for the Adriatic Sea I found 
> that until now Asychis gotoi and Asychis biceps were recorded. In the 
> meantime these species obviously changed the names.
> In my samples I have found something similar to the Asychis biceps 
> described in the Fauvel's "Faune de France. Polychetes sedentaires". But 
> I cannot relie on that literature, since it is pretty out of that. So 
> the species that I have might be Metasychis gotoi as well...
> Can you reccomand me some literature that could help me in the 
> determination of this genus?
> Many thanks,
> Barbara Mikac
> Marine Research Centre
> Rudjer Boskovic Institute
> G. paliaga 5
> 52210 Rovinj
> Croatia

  Geoff Read <g.read at niwa.co.nz>

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