Akantharges

Order:  LICHIDA  Moore, 1959

Superfamily: LICHOIDEA sensu Fortey (Fortey in Kaesler 1997)

Family: LICHIDAE  Hawle & Corda, 1847

Subfamily: TROCHURINAE  Phleger, 1936

Genus AKANTHARGES  Phleger, 1936

 

Diagnosis

see below.

 

Occurence

Basseiarges occurs in the Eifelian of Southern Morocco.

 

Recognizing Akantharges species

There are three species of Akantharges known: Akantharges  gourdoni (Barrois, 1886) from France, Akantharges erbeni (Meischner, 1965) and Akantharges mbareki (Corbacho & López-Soriano, 2013). Only the last two occur in Morocco and will be described here.


Picture will follow

Akantharges erbeni

Meischner, 1965 (Eifelian-Givetian)

info will follow


Akantharges mbareki

Akantharges mbareki

Corbacho & López-Soriano, 2013   (Eifelian)

 

Akantharges has a cephalon and pygidium that have more or less the same size (isopygous). The body is elliptical in outline.

Cephalon:
The cephalon is subtriangular and it is wider than it is long. The glabella is broad and strongly convex. It overhangs the anterior border slightly. The furrow is as long as the occipital ring. The genal spines are pointing a bit outwards and are covered with bulbous blunt serrations both on top as on the bottom. They reach almost to the pygidium and are covered with tubercles. The upright cheeks have small tubercles and pits. The eyes are small and placed low on the fixed cheeks (fixigena), rather far from the glabella.

Thorax:
The thorax has 11 segments and is evenly wide above as below. The rachis (axis) is slightly vaulted, with granulations. The dorsal furrows are well defined. The thoracic pleurae have small tubercles but no furrows. They finish in strong, straight and sharp pleural tips.

Pygidium:
The pygidium is semicircular with a thick section.  The axis is vaulted and has a well-defined axial pygidial ring that is followed by 8 additional rings. The pygidial edge is high and carries 3 pairs of marginal spines. The center pair is much shorter and is placed in the postrachial area. All spines are rounded in form. The pygidium is covered with tubercles of which the ones on the axis are paired. There are 3 pairs of pleural ribs, very well differentiated by deep and wide furrows. These end in 3 or 2 tubercles orientated upwards.

 

Pictures used with permission from Corbacho & López-Soriano


References

J. Corbacho and F. J. López-Soriano. 2013. Two new species of Trochurinae trilobites from the Middle Devonian (Eifelian) of Southern Morocco. Batalleria 18:15-24