Revision of the bryozoan genus Gephyrotes Norman, 1903 (Cheilostomata, Cribrilinidae) with the description of two new taxa
Author
Martino, Emanuela Di
Author
Rosso, Antonietta
text
Zootaxa
2015
3941
2
261
283
journal article
10.11646/zootaxa.3941.2.7
18eee934-ff31-4f31-8dcb-e771013673aa
1175-5326
253825
9FC33747-4C50-4D56-81D1-69B9930698B7
Genus
Tricephalopora
Lang, 1916
Revised diagnosis.
Zooids with typically paired adventitious avicularia lateral to orifice, these often extending across its margin at a variable position and contributing to the formation of the peristomial rim, or projecting into the secondary orifice and affecting its shape. Frontal shield visible only medially as peripheral area surrounded and covered by thick skeletal calcification associated with interzoooidal kenozooids; costae lacking intercostal bridge and separated by a single, large, intercostal pore; raised peristomial rim formed by a band of calcification seemingly partially derived from kenozooids.
Type
species.
Cribrilina triceps
Marsson, 1887
.
Remarks.
The genus
Tricephalopora
shows affinities with
Gephyrotes
in general aspect, particularly in the raised, collar-like peristomial structure and the highly developed kenozooidal network. However, the peristomial constructions are formed differently in the two genera—they result from kenozooidal secondary calcification in
Tricephalopora
but from the bifurcation of the distalmost pair of costae in
Gephyrotes
. Further differences are seen also in the degree of kenozooidal development. In
Tricephalopora
, kenozooids are responsible for a massive spread of secondary calcification, lacking frontal openings, that covers much of the zooidal frontal shield, leaving only a reduced window exposed, whereas kenozooids in
Gephyrotes
are strictly interzooidal, and narrow and tubular with numerous openings. Their overall general similarity caused the inclusion in
Gephyrotes
of several species that better conform to
Tricephalopora
.
Taylor & McKinney (2006)
first transferred
Gephyrotes lamellaria
Canu & Bassler, 1926
to
Tricephalopora
, and further species are here assigned to this genus.
Distribution.
Coniacian–Thanetian of Europe and North
America
(
Fig. 1
).