Latoucheia (Pseudolenus) ourikaensis Hupe 1953

Part of the sub-family Protoleninae.  Hamatolenus, a more common genus, is often mistaken for this sub-genus of`Latoucheia, Pseudolenus ourikaensis.  Perhaps this is a result of reliance on older diagnoses.  Geyer's study is newer (1990, see main page) but not readily available or known to American collectors, so hopefully, this website will in some ways disseminate, though imperfectly, more updated diagnoses.  Pseudolenus is not a genus but a sub-genus of Latoucheia, and ourikaensis reflects the geographical location where these have been found.

The L.Pseudolenus differs from Hamatolenus genus in a number of ways.  The Latoucheia genus is usually characterized by a smaller glabella (than Hamatolenus and other Protoleninae) with sides parallel, however, the sub-genus Pseudolenus has a larger glabella compared with the genus type (40% of the cranidium between the palpebral lobes width-wise). The palpebral lobe does not become a para-frontal band and is more limited in length.  The pre-glabellar field is more prominent and is not flat but higher towards the glabella and lower towards the anterior border.  The anterior border is not as wide.  This particular specimen is on the same plate as a Cambropallas telesto and so is on the same layer as the ones mined in Tarhoucht which is Lower Middle Cambrian, Tissafinian Stage, Cephalopyge notabilis zone.

 

This close-up shows the pre-glabellar field failrly well even though the preservation of that area is slightly compressed.  The faint lines of the palpebral lobe can be seen.  What is remarkable in this specimen is the preservation of the eye ridge parallel to the glabella and under the palpebral lobe.  This is one of the key characteristics of this sub-genus according to Hupe's original description, that it had bifurcated palpebral lobes explained by the eye ridge.  It is more visible in this specimen than the palpebral lobe which is unusual for Cambrian trilobites.  The genal spines are more stout and broader than on Hamatolenus or Protolenus. 

The rare preservation shows the shape of the pygidium, very different from either Hamatolenus or Protolenus being sub-quadrate and somewhat fan shaped with an oval piece in the inside center.

Kenjiro 2015.6.5. (edited 2020.5.3.)