Carbotubulus waloszeki gen. et sp. nov.

Etymology. “Carbo,” L. referring to the stratum Carboniferous; “tubulus,” L. “small pipe,” referring to the form of the appendages; in honor of Dieter Waloszek, University of Ulm, Germany, in recognition of his work on arthropod evolution.

Holotype and Only Known Specimen. Royal Ontario Museum (ROM) 47514, part and counterpart, Invertebrate Palaeontology collection, Royal Ontario Museum, Toronto.

18 Johnson R.G.

Richardson Jr., E.S. A remarkable Pennsylvanian fauna from the Mazon Creek area, Illinois. 19 Baird G.C.

Shabica C.W.

Anderson J.L.

Richardson Jr., E.S. Biota of a Pennsylvanian muddy coast: habitats within the Mazonian Delta Complex, northeast Illinois. Stratigraphic Horizon and Locality. Carbondale Formation, Francis Creek Shale Member, Mazon Creek area, Pit 11, Essex fauna [], Illinois, USA.

Diagnosis. Lobopodian with prominent cylindrical head region comprising one-third of body length, nine pairs of long, tube-shaped walking limbs (lobopods), and an additional pair of small appendages associated with head region; body surface smooth.

Measurements. Body nearly seven times longer than wide (total preserved length 35 mm, diameter 4.8 mm); limbs at least 11 mm long (the appendage length may vary in different body areas, so we based this measurement on the longest preserved appendage, number 8) and 2 mm in diameter (the diameter of appendages 7 and 9 appears greater, but this is interpreted as an effect of a very oblique breakage plane).

Figure 1 Comparison of New Long-Legged Lobopodian and Associated Short-Legged Ilyodes inopinata Show full caption (A–E) Carbotubulus waloszeki, ROM 47514. (A) Part (counterpart in Figure S1 ); legs numbered. Note lack of body annulation and presence of longitudinal wrinkles. (B) Anterior region with two pairs of circular spots (arrows). (C) Lateral body region; lobopods 3 and 4 showing smooth surface. (D and E) Legs sticking out of the nodule (arrows). (F and G) Ilyodes inopinata, ROM 47978. (F) Part (counterpart in Figure S2 ); arrow points to putative slime papilla. (G) Annulated skin with papilla-like structures.

Figure 2 Three-Dimensional Model of Carbotubulus waloszeki Show full caption Presumed life position, with anterior end to the left; surface color hypothetical.