Haplograptus wisconsinensis
Cambrian, Wisconsin, U.S.A. Holotype.
From Ruedemann.
Haplograptus wisconsinensis, the type species
of the genus
Haplograptus, was described by Rudolf
Ruedemann from the Cambrian (Trempealeau
formation) of two localities in Wisconsin. Later, it was
listed also by Decker (1936) from the middle
Arbuckle limestone of Oklahoma.

Description by Ruedemann (1947, p. 264):

"Rhabdosome consisting of a single
sicula or theca or a few thecae produced
by irregular budding. Sicula (?) an
arched or straight slender  cone, about
9-12 mm long and 1-1.5 mm wide at
aperture. First theca originates close
to aperture of supposed sicula, the
others irregularly wide at aperture.
They probably do not reach size of
sicula for the first theca in the
specimen measures but 0.4 mm long when
it has already produced two budding
thecae in its turn."
List of species:

Haplograptus canadensis Ruedemann, 1947; Ordovician, Canada.
Haplograptus fruticosus Yu Jian-hua, Liu Huai-bao & Fang Yi-ting, 1985
Haplograptus sinicus Mu  et al.
   Haplograptus sinicus minutus Yu Jian-hua, Liu Huai-bao & Fang Yi-ting, 1985;  early Ordovician, China.
Haplograptus vermiformis Ruedemann, 1947; Upper Cambrian, U.S.A.
Haplograptus wisconsinensis Ruedemann, 1933; Cambrian, U.S.A.
Diagnosis of Haplograptus by O.M. B. Bulman
(1955, 1970):

"Elongate conical or vermiform thecae
associated to form an irregularly dendroid
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R e f e r e n c e s :

Decker, C. E. 1936. Some tentative correlations on the basis of graptolites of Oklahoma and Arkansas. -
American Assoc. Petrol. Geol., Bull., 20, 3, 301-311.

Ruedemann, R. 1933. Cambrian graptolite faunas of North America. - Milwaukee Pub. Museum, Bulletin, 12,
3, 307-348

Ruedemann, R. 1947. Graptolites of North America. - Geological Society of America, Memoir 19.

Sennikov, N.V. 1996. Paleozoic graptolites from the Central Siberia.  Published by Siberian Branch SPC UIGGM
SB RAS, Novosibirsk, 227pp.
The graptolite-like fossil genus Haplograptus was proposed by
Ruedemann (1933) in order to embrace two species:
Haplograptus wisconsinensis Ruedemann, 1933 (type species
of the genus) and
H. vermiformis Ruedemann, 1933. These
forms were recovered from the Cambrian of U.S.A.  Further
findings of this genus were obtained from the Cambrian of
China and Siberia, and from the Ordovician of Canada.

       Ruedemann (1947) and some other writers placed
Haplograptus among the Dendroidea. Bulman (1955) treated
this form as representative of his  dendroid family
Chaunograptidae. Finally, he placed it among graptolite-like
fossils of uncertain taxonomic position (Bulman 1970).
Haplograptus Ruedemann, 1933
Haplograptus is mentioned also here and here.