Aengapentastomum

Aengapentastomum Temporal range:
A reconstruction of Aengapentastomum
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Ichthyostraca
Subclass:	Pentastomida
Genus:	†Aengapentastomum Waloszek, Repetski & Maas, 2005
Species:	†A. andresi
Binomial name
†Aengapentastomum andresi Waloszek, Repetski & Maas, 2005

Aengapentastomum is a Cambrian genus of pentastomid from the Orsten of Sweden, containing one species, Aengapentastomum andresi.

Description

Aengapentastomum is roughly 730 micrometers long from head to tail. Unlike other Cambrian pentastomids, it lacks vestigial trunk limbs, therefore it is likely closer to the crown-group. It has two pairs of head limbs, both smooth and rounded, with inward-facing podomeres. A swelling of unknown function, likely akin to the "dorsal organs" of modern pentastomid larvae, occurs roughly half-way down the length of the body. The tail has a rounded end, with two structures at its tip. The head is subtriangular, with no head shield, despite a furrow around the appendages and a prominent margin giving the effect of one at some angles. The trunk is unsegmented, with seemingly no annulations either. Aengapentastomum is known from one complete specimen, with an earlier described larva also resembling it, however this larva is much smaller and only has one pair of appendages, therefore it is likely either an earlier developmental stage or a close relative. This genus, alongside other Orsten pentastomids, is likely a larval form with the adults not being preserved.

Etymology

Aengapentastomum derives from the Änga quarry where it was found, alongside the fact it is a pentastomid. The species name andresi honours Dietmar Andres, who first described pentastomid fossils from the Orsten.