Two new species and a new combination in the genus Pauridiantha Hook. f. (Rubiaceae) from tropical Africa
Author
Salvator NTORE
Author
Olivier LACHENAUD
text
Adansonia
2019
2019-04-08
41
4
29
40
journal article
26954
10.5252/adansonia2019v41a4
9dfbe7ab-f1ae-49ff-af7b-14dff6879995
2653394
Pauridiantha
Hook.
f.
In Genera Plantarum
2: 69 (1873). —
Typus
:
P. canthiiflora
Hook.f.
Rhipidantha
Bremek.,
Botanische Jahrbücher
für Systematik, Pflanzengeschichte und Pflanzengeographie
71: 222 (1940),
syn. nov.
—
Typus
:
R. chlorantha
(K.Schum.) Bremek.
REMARKS
Rhipidantha
has always been regarded as a monospecific genus endemic to the Uluguru Mountains of
Tanzania
. Its only species was originally described in
Urophyllum
Wall. (
Schumann 1899
: 57)
before
Bremekamp (1940)
erected a new genus for it. Bremekamp separated
Rhipidantha
from
Pauridiantha
by its (4-)5-locular ovary (vs 2-locular in
Pauridiantha
), and from
Poecilocalyx
by its lax and pedunculate inflorescences, dentate (vs deeply lobed) calyx, sessile stigmas (actually connate into a style, though very shortly so in brevistylous flowers) and absence of conspicuous indumentum.
Verdcourt (1976)
accepted the genus as distinct from
Pauridiantha
, chiefly based on the number of ovary locules, but the subsequent inclusion of
Commitheca
(with 2- to 4-locular ovaries) and
Poecilocalyx
(with 2- to 5-locular ovaries) in
Pauridiantha
makes this character no longer reliable. In fact, on morphological grounds
Rhipidantha
is even closer to
Pauridiantha
s.str.
than are
Poecilocalyx
and
Stelechantha
(both of which are now included in
Pauridiantha
), and its great similarity to
Pauridiantha insularis
(Hiern) Bremek.
has already been noted by
Ntore (2008
: 109). The fruits and seeds of
Rhipidantha
, previously unknown, have recently been collected and also agree very well with the genus
Pauridiantha
- the seeds in particular (
Fig. 1A, B
) are extremely similar to those of
P. insularis
, illustrated in
Ntore (2008
: fig. 29). Therefore, despite the absence of molecular data for
Rhipidantha
, there can be no reason for keeping the two genera separate.
KENYA DEMOCRATIC REPUBLIC OF THE CONGO
TANZANIA
500 km
FIG. 2. — Distribution map of
Pauridiantha chlorantha
(K.Schum.) Ntore & O.Lachenaud
,
comb. nov.
The inclusion of
Rhipidantha
in
Pauridiantha
requires the new combination below. Since
R. chlorantha
is rather little-known and its previous descriptions (
Schumann 1899
;
Bremekamp 1940
;
Verdcourt 1976
) were incomplete on several points, a complete and updated account of this species is presented here.