Trilobite question

[digsrocks73]

I know that Metacanthina is now called Hollardops but I have a Hollardops that has a spine right on the center of the cephalon where it meets the thorax. Is this a Hollardops or something else.Thank anyone for advice.

[Kane]

Was it reassigned? I thought Metacanthina was still a valid genus name. 

 

Could you provide a picture? Apart from being able to assess it better, it is always nice to have some trilobite eye candy.  

 

My source (Lebrun, 2018) lists these: 

 

Metacanthina issoumourensis (Morzadec, 2001) 

Metacanthina maderensis (Morzadec, 2001)

Metacanthina munieri (Oehlert, 1871)

Metacanthina wallacei (Termjer & Termier, 1950)

 

 Here's some images of my own M. issoumourensis with that spiny occipital ring protuberance:

 

 

[digsrocks73]

I have no way of posting a photo now that I lost photobucket and camera will no longer take close ups? In any case yours is exactly what mine looks like with the spine on the occipital ring .

The other hollardops I have do not have the spine. Also the border of the cephalon is round on the hollardops while this one has a small round tab at the front as yours does. I am a little mixed up as the wikipedia under Metacanthina shows them now renamed as hollardops, that is where my  "I don't know" came from. I bought this as a metacanthina. I take it that Metacanthina is still a valid name ?

[Kane]

Yeah, the entry on Wikipedia does say they were reassigned in 1997, but then I keep tripping on articles published since that still use Metacanthina. Either it was reclassified and other trilobite workers haven't caught on, or ... who knows?  The one I have here was sold as M. barrandei, but a fellow trilo expert who visited said it was M. issoumourensis. Like you, my other Hollardops also has a round ring and no tab-like spathe.

 

But this taxonomic question is going to drive me bonkers until we can know for certain! Let me use the forum bat-signal to get @piranha to tell us!

[digsrocks73]

That would be great. I have already switched once from Asteropyge and  feels like confusion rules. I can't believe they are the same as a 5 yr. old could see the difference.

[Tidgy's Dad]

I'm not certain, but I think there was a revision in 1997 which put some of the Metacanthina into the new genus Hollardops.

But Metacanthina still survived as a valid genus with some species included. 

https://www.researchgate.net/publication/285666114_Asteropyginae_trilobites_from_the_Devonian_of_the_Ougarta_Algeria

This one, I think. 

[piranha]

3 hours ago, Kane said:

My source (Lebrun, 2018) lists these:

Metacanthina issoumourensis (Morzadec, 2001) 

Metacanthina maderensis (Morzadec, 2001)

Metacanthina munieri (Oehlert, 1871)

Metacanthina wallacei (Termjer & Termier, 1950)

 

 

"Metacanthina munieri" is incorrect in Lebrun 2018.  He mentions this species twice and fortunately is correct where it is cited as: Pseudocryphaeus munieri (Oehlert 1877).

 

Oehlert, D.V. 1877

Sur le fossiles du départment de la Mayenne. [On the fossils of the department of Mayenne.]

Bulletin de la Société géologique de France, 2nd Series, (Ser.3) 5:578-603