Revision of Lithostrotionella - USGS

SYSTEMATIC PALE ONTOLOGY 31
Discussion.-This species differs from P. wagneri by
having more major septa, more tabulae, and strongly
dilated corallite walls.
Occurrence.- Middle Carboniferous, Bashkirian.
PerapertU Formation, Palencia, Spain.
Petalaxis radians (de Groot)
Lithostrotionella (Hillia) radians de Groot, 1963, p. 89, pl. 20, figs.
la-c.
Diagnosis.-Petalaxis with corallite diameter 7 to 9
mm and 15 to 18 major septa that closely approach the
columella but seldom reach it and extend into the
dissepimentarium, ordinarily being attached to the corallite
wall. Minor septa ordinarily well developed. Columella
a simple axial plate connected to the counter or
cardinal septum. Dissepimentarium weakly lonsdaleoid,
composed of 1 to 3 rows of inflated dissepiments of varying
sizes. Tabulae incomplete, horizontal, mostly convex,
and irregularly spaced 0.25 to 1 rrim apart. Ratio of
tabularium width to corallite diameter about 0.5 to 0.6.
Mode of increase unknown.
Description of type material.-See de Groot (1964
[1963])..
Discussion. -This species differs from P. wagneri by
having larger corallites, more rows of dissepiments, and
less regular tabulae.
Occurrence.- Middle Carboniferous, Bashkirian.
Perapertu Formation, Palencia, Spain.
Petalaxis intermedius (de Groot)
Lithostrotionella (Hillia) intermedia de Groot, 1963, p. 90, pl. 20, figs.
2a, b, 3.
Diagnosis. -Petalaxis with corallite diameter 5 to 7
mm and 16 to 19 major septa that closely approach the
columella but seldom reach it and extend into the
dissepimentarium, commonly being attached to the corallite
wall. Minor septa well developed. Columella a simple
axial plate connected to counter or cardinal septum.
Dissepimentarium weakly lonsdaleoid, CQmposed of 1 to
4 rows of mostly small inflated dissepiments. Tabulae
mostly incomplete, flat, concave or convex, horizontal,
and irregularly spaced 0.25 to 0. 75 mm apart. Ratio of
tabularium width to corallite diameter about 0. 7 to 0.8.
Increase peripheral.
Description of type material.-See de Groot (1964
[1963]).
Discussion. -This species differs from P. wagneri by
having larger corallites, more major septa, and more
tabulae.
Occurrence.- Middle Carboniferous,_ Bashkirian.
Perapertu Formation, Palencia, Spain.
Petalaxis santaemariae (de Groot)
Lithostrotionella (Hillia) santaemariae de Groot, 1963, p. 91, pl. 21,
figs. la-e.
Diagnosis.-Petalaxis with corallite diameter 3.5 to 8
mm and 16 to 19 major septa that closely approach the
columella but seldom reach it and extend into the
dissepimentarium, ordinarily attached to the corallite
wall. Minor septa poorly developed. Corallite walls
strongly dilated. Columella a simple thickened axial
plate connected to counter or cardinal septum.
Dissepimentarium weakly lonsdaleoid, composed of a
single row of small inflated dissepiments. Tabulae mostly
complete, horizontal, mostly concave, and irregularly
spaced 0.25 to 1 mm apart. A peripheral zone of
clinotabellae may be present. Ratio of tabularium width
to corallite diameter about 0.8. Increase peripheral.
Description of holotype.- See de Groot (1964 [1963]).
Discu,ssion.- This species differs from P. perapertuensis
by having larger corallites, poorly developed minor
septa, and fewer tabulae.
OccU'rrence.- Middle Carboniferous, Bashkirian. Santa
Maria Limestone, Palencia, Spain.
.Petalaxis cantabricus (de Groot)
Lithostrotionella (Hillia) cantabrica de Groot, 1963, p. 92, pl. 22, figs.
1-4.
Diagnosis. -Petalaxis with corallite diameter 4 to 8
mm and 19 to 28 major septa that closely approach the
columella but seldom reach it and extend into the
dissepimentarium, ordinarily being attached to the corallite
wall. Minor septa well developed. Cora!lite wall
strongly dilated and denticulate. Columella a simple
commonly thickened axial plate connected to counter or
cardinal septum. Dissepimentarium weakly lonsdaleoid,
composed of 1 to 3 rows of small inflated dissepiments.
Tabulae mostly complete, horizontal, concave, and
spaced 0.2!5 to 1 mm apart. A peripheral zone of
clinotabellae may be present. Ratio of tabularium width
to corallite diameter about 0.6 to 0.7. Increase
peripheral.
Description of type material.- See de Groot (1964
[1963]).
Discussion. -This species is distinguished from all
others in the P. wagneri species group by having more
major septa.
Occurrence.- Middle Carboniferous, Bashkirian to
Moscovian(!'). Santa Maria Limestone, Perapertu Formation,
and Celada Limestone, Palencia, Spain.
Petalaxis orboensis (de Groot)
Lithostrotionella orboensis de Groot, 1963, p. 85, pl. 17, figs. 2a-d.
Diagnosis. -Petalaxis with corallite diameter 4.5 to 8
'mm and 16 to 21 major septa that closely approach the
columella but seldom reach it and extend into the
dissepimentarium, commonly being attached to the corallite
wall. Minor septa well developed. Columella a simple
axial plate connected to counter or cardinal septum;