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Mesophyllum (Arcophyllum)
Taxonomy
Mesophyllum (Arcophyllum) was named by Markov (1926). It is not extant.
It was assigned to Mesophyllum by Markov (1926), Hill (1956) and Merriam (1974).
It was assigned to Mesophyllum by Markov (1926), Hill (1956) and Merriam (1974).
Species lacking formal opinion data
Mesophyllum daviesi, Mesophyllum funafutiense, Mesophyllum heteroclitum, Mesophyllum lissingenense, Mesophyllum macrocystis, Mesophyllum monielloense, Mesophyllum prepulchrum, Mesophyllum prolifer, Mesophyllum savorninii, Mesophyllum schenki, Mesophyllum secundum, Mesophyllum vaughanii, Plasmophyllum sandhillense
Synonymy list
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
Subg. †Mesophyllum (Arcophyllum) Markov 1926
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| C. W. Merriam 1974 | The solitary Digonophyllinae have large, commonly elongate subcylindrical mature growth stages with thick external annulations and rejuvenescence constrictions. The calice, deep and inversely bell shaped to funnel shaped, is reflected peripherally as a platform or brim, which is either inclined axially, flattened, or broadly convex distally. The brim surface is ornamented by numerous edges of strip carinae. Septa are numerous, somewhat with- drawn from axial tabellae, and range from continuous to discontinuous as radially alined septal crests, the more continuous septa predominate. Septa are thick- ened locally in the tabularium; septa pass peripher- ally into a wide band of irregular dissepiments, within which some septa terminate short of the outer wall. Concentric rows of strip carinae are vaguely defined peripherally in transverse thin sections; outermost strip carinae are commonly detached from the septa with which they are alined. Minor septa range from about one-half to nearly full length of the major septa; minor septa are more prone to discontinuity as alined septal crests. The dissepimentarium is wide, is com- monly three-fourths of corallum radius, and consists of mostly small steeply inclined dissepiments which pass axially without discontinuity into the narrow medial zone of the tabellae. Outer dissepiments are mostly lonsdaleioid; inner dissepiments form concen- tric irregular chevrons and forks. Flat continuous tabu- lae are few. In longitudinal thin section, prominent isolated groups of diagonally inclined strip carinae abut in the outer dissepimentarium against parts lacking carinae. |