Diptera.info

Posted by nielsyese on 07-12-2017 17:38

Hi everybody,
I'm struggling with the taxonomy of the two Dutch Parallelomma species. When I look in the checklist by Beuk, I can see two species:

* Parallelomma media Becker, 1894
* Parallelomma vittata (Meigen, 1826)

When I look in the key from Ball (2007), Key to the British Scathophagidae (Diptera), two species are mentioned:
* Parallelomma paridis Hering, 1923
* Parallelomma vittatum (Meigen, 1826)

Of course it might be possible that paridis is another species that occurs in Britain, but not in the Netherlands, so I was also checking www.bladmineerders.nl. This is a website about all mining flies in the Netherlands. They mention two species: Americina vittata and Americina media. But when I look for the synonyms of Americina vittata, I find:

Chylizosoma vittatum; Parallelomma paridis (Hering, 1923); P. convallariae (Kaltenbach, 1873); P. beckeri Séguy, 1932; P. paucheti Séguy, 1932; P. hostae Hering, 1955; P. sasakawae Hering, 1955; P. albamentum Séguy, 1963.

So: we have a species called Americina vittata synonym with Parallelomma paridis, which is in the key from Ball together with Parallelomma vittatum. I think this is really strange!!

Can somebody clarify this issue for me?:)

Posted by Steve Crellin on 12-12-2017 13:42

I don't know if this will help or note but this is the note on Parallelomma in the British checklist.
http://www.dipteristsforum.org.uk/documents/BRITISH_ISLES_CHECKLIST.pdf page 369.

"1. Parallelomma paridis Hering, 1923 was synonymised with vittatum by Šifner (1978), but reinstated by Nelson (1990). Šifner
(1995, 2008) reaffirmed this synonymy, which had not been accepted by Gorodkov (1986), but Nelson's view is accepted here."

I think it comes down to whether you follow Sifner's view that there is only one species or Nelson/Gorodkov that there are two species of Paralleloma.

Posted by Paul Beuk on 12-12-2017 15:00

I do not have Nelson's papers on Scathophagidae so I could not comment. There is a similar 'crisis' with some of the Scathophaga species with unclarity which names belong with two species.

Part of my correspondence with MArco Bernaconi:

Before the molecular [by Bernasconi et al.] work there were also two different interpretations dealing with these two species:
S. suilla (=S. taeniopa) and S. ordinata [Sifner, 1975, 1995]
S. suilla and S. taeniopa (=S. ordinata) [Gorodkov, 1986]

Sifner (2008) decided to accept the name taeniopa after all and he refers to Gorodkov's list of 1986: "Synonymized by GORODKOV (1986: 34)". However, I think he made an error in accepting that Gorodkov's listing in the catalogue as synonymization. Gorodkov used the name taeniopa earlier for a valid species (Insects of Mongolia, not available to me). At the same time he may not have been aware of ordinata as separate species or already accepting that as synonym of taeniopa. In either case, Sifner formally synonymized suilla and taeniopa in 1975 and my assumption is that Gorodkov, whilst preparing the 1986 catalogue, was not aware of it or chose to ignore it since he does not state a reference where the synonymization by Sifner is refuted.
For the name taeniopa to become available again it should have been resurrected from synonymy or someone should have stated in no uncertain terms that Sifner was wrong to synonymize these species in 1975. As far as I know, neither was done and, in my view, Gorodkov, 1986 does not do it either.

So [...] how it came to be that the name taeniopa was used [in the molecular works]. I assume it can be traced back to the keys used for identification of the species. Are you aware which keys were used to identify the species in the molecular work?

Perhaps a bit academic but it seems a valid question nevertheless since no-one seems to have examined the type of taeniopa to see with which species it actually agrees...