Paraclausocaris, Laville & Forel & Charbonnier, 2023

Laville, Thomas, Forel, Marie-Béatrice & Charbonnier, Sylvain, 2023, Re-appraisal of thylacocephalans (Euarthropoda, Thylacocephala) from the Jurassic La Voulte-sur-Rhône Lagerstätte, European Journal of Taxonomy 898 (1), pp. 1-61 : 29

Genus Paraclausocaris gen. nov.

urn:lsid:zoobank.org:act:BE0312F9-B192-4581-A2CB-3CC408857206

Type species

Paraclausocaris harpa gen. et sp. nov. by monotypy.

Diagnosis

Thylacocephala with a well-developed optic notch restricted to the ventral margin, a sharp antero-ventral angle, small sinuous ridges on the shield and raptorial appendages 3 having spines on the second and third podomeres of the distal part.

Etymology

From the Latin ‘ par, paris ’ (‘close to’) and Clausocaris Polz, 1989 .

Remarks

Paraclausocaris gen. nov. has many similarities with Clausocaris : a cone-shaped shield in lateral view, a dorsal midline with sharp, short serrations and long, thin raptorial appendages relative to the shield. However, it also displays some differences, including a well-developed posterior margin and an anterior margin with an optic notch limited to the ventral part of the margin for Paraclausocaris , while in Clausocaris the posterior margin is absent and the optic notch occupies the whole margin. As a result of these differences, we erect Paraclausocaris .

One last morphological trait should also be discussed here: the number of posterior trunk appendages. In Paraclausocaris gen. nov., we recognize nine pairs of posterior trunk appendages. Arduini (1992) described eight posterior trunk appendages in Clausocaris pinnai , but based on pictures from Dalla Vecchia (2012), there may actually be nine as in Paraclausocaris . However, it is different from the number reported by Polz (1990) or Haug et al. (2014) for Clausocaris lithographica . They respectively reported 10 or 11 posterior trunk appendages for this species. Interspecific variation in the number of posterior trunk appendages is not uncommon among Thylacocephala ( Schram 2014) . However, it is quite unusual to find such variation among closely related forms: for instance, eight posterior trunk appendages are usually reported in Concavicaris species ( Schram 2014). Thus, it will be necessary to revise C. pinnai to confirm its assignment to Clausocaris .