1964, 9 (1): 31–36
The fern genus Diplaziopsis C. Chr. of Index Filicum has long been considered as
a monotypic one, with the sole species, D. javanica (B1.) C. Chr. from tropical Asia. In
1906, H. Christ described a second species, Allantodia cavaleriana Christ (=D. cavaleriana C. Chr.) from Kweichow, West China, but this was since not fully recognized by
fern students in general, being often considered as a variety of the first species. This
is certainly a mistake, as is shown by ample herbarium specimens today. In the recent
work on the genus, the writer has found among the herbarium material two additional
new species from China, thus bringing the genus up to four species in Asia, mainly from
China, where, as it is, the genus has its center of development from the long past.
Phylogenetically, Diplaziopsis C. Chr. represents one of the offshoots from the great
stock of diplazioid ferns, of which the genus Diplazium Sw. constitutes the main body
of the group and from which our genus differs chiefly in its leaves of a thin texture with
reticulated venation, but not so much in its type of indusium as it has generally been
emphasized by most botanists in the past, for, as it is, the type of indusium in Diplaziopsis also prevails in many species of Diplazium, for which C. B. Clarke (Trans.
Linn. Soc. ser. 2, Bot. I:495, 1880) created, but really superfluously, a subgenus Pseudallantodia, about which the writer will dwell in another paper in the near future. Suffice
it to say here that the indusium in Diplaziopsis as revealed by the species treated here
is, indeed, typical of diplazioid ferns, only often, as it happens, with its adaxial edge
pressed so tight under the expanding sorus that it is unable to open freely along its upper
free edge and, as a result, its thin vaulted back bursts open from the pressure of the expanding sorus underneath.
As a result of the present study, following four species of the genus have been recognized.
Diplaziopsis javanica (B1.) C. Chr. Ind. Fil. (1905) 227.
Wide spread in tropical Asia, northwardly to Bakbo and the southern part of Yunnan, China.
D. cavaleriana (Christ) C. Chr. Ind. Fil. Suppl. I (1913) 25.
Ranges from West China through northern part of Fukien of East China to Japan.
D. intermedia Ching, sp. nov.
Endemic in West China: Mt. Omei, Szechuan, and Kweichow.
D. hainanensis Ching, sp. nov.
In conclusion, it may be pointed out that with the modern plant taxonomy pursued
in a more efficient manner than in the past, and especially by the introduction of the
cytotaxonomic methods, the so-called “monotypic genera”, as conceived by the orthodox
systematists, will continue to prove, to a great extent, to be lack of enough scientific
ground. The fact that the “monotypic genus” of Diplaziopsis C. Chr. is now found to
be a genus of four well-defined species is once again an instance to illustrate the pointat issue.