R. Posenato, The athyridoids of the transitional beds between Bellerophon and Werfen Formations (uppermost Permian, Southern Alps, Italy), RIV IT PAL, 107(2), 2001, pp. 197-226
Citations number
31
Categorie Soggetti
Earth Sciences
Journal title
Rivista italiana di paleontologia e stratigrafia (Testo stampato)
The transitional beds between Bellerophon and Werfen formations, few centim
etres thick and latest Permian in age, contain a brachiopod fauna with a re
latively rich athyridoid assemblage, among which Janiceps is the most commo
n and characteristic genus. The internal morphology of the type species (J.
peracuta) is here described for the first time, and a taxonomical revision
of the South Alpine species is proposed. The new subfamily Janicepsinae is
proposed, which contains Janiceps and the new genus Comelicothyris. Among
the latter genus, Comelicothyris laterosulcata n. sp. is suggested. Lectoty
pes are selected and illustrated for Spirigera janiceps Stache, S. confinal
is Stache, S. bipartita Stache, S. ? arcbimedis Stache, Spirifer ? sextensi
s Stache, Athyris irregularis Merla,A, semilunaris Merla, and A. janiceps v
ar. globulus Merla.
The athyridoids of the transitional beds are characterized by a broad morph
ological variability which induced past authors to create many species and
"varieties", generally on the basis of a single or few individuals. As conc
erns Janiceps, only four species -versus the 14 species and 7 "varieties" c
ited in the literature of the Southern Alps- are here considered valid [J.
peracuta (Stache), J. cadorica (Stache), J. papilio (Stache), and J. bipart
ita (Stache)]. Besides, other four species are identified here; these are:
Comelicothyris recticardinis (Merla), Septospirigerella ? sp., Spirigerelli
nae gen. et sp. indet., and Comelicania merlai Posenato.