Myriotheca arnoldii

Name

Myriotheca arnoldii

Rank

Species

Original spelling

arnoldi

Generic Name

[Genus] Myriotheca

Authors (Name)

Pfefferkorn H. W.  

Authors (Pub.)

Pfefferkorn H. W. Peppers R. A. Phillips T. L.  

Publication

Some fern-like fructifications and their spores from the Mazon Creek compression flora of Illinois (Pennsylvanian) [1971]

Journal

Circular / Illinois State Geological Survey

Issue

463

Page number

15

Year

1971

Fossil Status

foliage (fertile)

Stratigraphy

Moscovian

Strat. comment

Francis Creek Shale Member above Colchester (No. 2) Coal Member. Carbondale Formation, Desmoinesian Series, Westphalian D

Location

Near Wilmington, Will County, Illinois, USA

Paleoregion

Laurussia (Laurentia)

Data for Holotypus

Repository

Illinois State Museum, Springfield, USA

Repository Number

ISM 15383 a and b (Langford Coll.)

Num

pL. 6: figs. 4-6, 8-9

Pub.

Some fern-like fructifications and their spores from the Mazon Creek compression flora of Illinois (Pennsylvanian) [1971]

Data for Paratypus

Repository

National Museum of Natural History, Smithsonian Institution, Washington, USA

Repository Number

USNM 43714 a, b

Num

pl. 6: fig. 1-3, 7

Pub.

Some fern-like fructifications and their spores from the Mazon Creek compression flora of Illinois (Pennsylvanian) [1971]

Diagnosis

The frond is pinnately divided, probably in several orders, but only the last one is preserved. The pinnules are up to 12 mm long and 6 mm wide. The shape of the lamina is not recognizable but is somewhat sphenopteroid. The pinnules are covered by sporangia on the abaxial side. The axis shows a weak longitudinal striation and is slightly winged. Sporangia are free, round, sessile, and 1.0 to 1.4 mm in diameter. There are about 35 sporangia on one pinnule; owing to the lobation of the pinnules, there is a tendency toward the occurrence of some groupings, made up of about eight sporangia. This grouping does not constitute the formation of sori. Spores are radial, trilete, and circular in transverse plane, and were originally spherical. The trilete marking is distinct, the suture is simple, and the rays extend about two-thirds the length of the spore radius, or about 26 nm. The rays are of equal length. The exine is laevigate. The spore wall is 3 to 4 um thick, and the diameters of the spores (29 measurements) vary from a maximum of 91 um to a minimum of 71 um, with a mean of 79 um.