New infrageneric taxa in Leucospermum (Proteaceae) and Tetragonia L. (Aizoaceae) and a new name in Aizoon subgenus Galenia (Aizoaceae) in southern Africa
Author
Manning, John
Author
Klak, Cornelia
text
Bothalia
2022
a 11
2022-07-18
52
1
1
5
http://dx.doi.org/10.38201/btha.abc.v52.i1.11
journal article
286006
10.38201/btha.abc.v52.i1.11
c2dbed47-91bf-4b32-ba19-6aac4b574387
2311-9284
10515159
2.
Tetragonia
L. (
Aizoaceae
: Aizooideae)
Tetragonia
L. (
Aizoaceae
: Azooideae) as recently recircumscribed, is a genus of ± 50 species from temperate and subtropical regions, mainly in the southern Hemisphere (
Klak et al. 2017
). The southern African taxa were last revised by Adamson (1955), and this remains the current treatment for the species in the region. In his classification, Adamson (1955) segregated the species among the four subgenera
Tetragonia
,
Tetragonoides
DC.
,
Anisostigma
(Schinz) Engl.
and
Tribulocarpus
(S.Moore) Adamson
, defined by several characters of the fruits and flowers. The recent molecular phylogenetic analysis of the subfamily by
Klak et al. (2017)
, however, uncovered some unexpected relationships among the species that necessitated realignments among several taxa in order to render them monophyletic. Among these was the removal of
Tetragonia
subgenus
Anisostigma
and subgenus
Tribulocarpus
to the new tribe
Anisostigmateae Klak
in subfamily
Sesuvioideae
as the genera
Anisostigma
Schinz
and
Tribulocarpus
S.Moore
respectively.
In addition to these changes, the circumscription of
Tetragonia
subgenus
Tetragonoides
was greatly altered by the removal from it of most of the southern African taxa previously included there by Adamson (1955).
Tetragonia
subgenus
Tetragonoides
is now understood to be essentially Australasian in distribution, with the exception of the cosmopolitan littoral species
T. tetragonoides
(Pall.) Kuntze
, the
type
of the subgenus. Two additional subgenera, subgenus
Tetragonella
(Miq.) Klak
and subgenus
Americanae
Klak
were established to accommodate respectively the other Australasian and the American species (
Klak et al. 2017
).
|
The remaining four southern African species that were included by Adamson (1955) in subgenus
Tetragonoides
were retrieved by
Klak et al. (2017)
as a clade sister to subgenus
Tetragonia
and were accordingly included in it, with the observation that the ‘series erected by Adamson (1955) should be maintained’. This alludes to the seven sections recognised by Adamson (1955) in subgenus
Tetragonia
. Although they included these additional four former members of subgenus
Tetragonoides
in subgenus
Tetragonia,
Klak et al. (2017)
did not accommodate them within the existing classification.
Significantly, the removal of
T. tetragonoides
from this group renders it morphologically more homogenous. The four species share a prostrate, ± annual habit and halfinferior ovary, and differ from all other members of subgenus
Tetragonia
in having the stamens less than twice as many as the perianth segments vs. more than twice as many as the perianth segments (Adamson 1955). The new series
Echinatae
J.C.Manning & Klak
is accordingly proposed here to accommodate them.
There are two other nomenclatural corrections required in subgenus
Tetragonia
. The first concerns the authorities for the infrageneric names that were published by Fenzl (1862). Adamson (1955) treats these as series, with Fenzl (1862) as author. However, examination of Fenzl (1862) reveals that they were published as third tier names two ranks below sectional level but without a definite rank. Although they are to be accepted as validly published by Fenzl (1862) they are to be treated as unranked (Turland et al. 2018: ‘Art.
37.3.
A name published
before
1 January 1953
without a clear indication of its rank is validly published provided that all other requirements for valid publication are fulfilled; it is, however, inoperative in questions of priority except for homonymy. If it is the
name
of a new taxon, it may serve as a basionym or replaced synonym for subsequent new combinations, names at new ranks, or replacement names at definite ranks.
’). Their later publication by Adamson (1955) with a clear indication of the rank of series serves as the first publication at that rank and they are therefore to be treated as combinations by Adamson (1955).
The second correction concerns the status of the series that includes the
type
of the genus,
T. fruticosa
L. Although
the genus
Tetragonia
was only lectotypified by Britton (1918) after the treatment by Fenzl (1862), the name
T.
[unranked]
Fruticulosae
Fenzl. (1862) is to be treated as not validly published [Turland et al. 2018: ‘Art.
22.2.
A name
of a subdivision of a genus that includes the
type
(i.e. the original
type
or all elements eligible as
type
or the previously designated
type
) of the adopted, legitimate
name
of the genus is not validly published unless its epithet repeats the generic
name
unaltered. For the purposes of this provision, explicit indication that the nomenclaturally typical element is included is considered as equivalent to inclusion of the
type
, whether or not it has been previously designated.
’]. Similarly, the publication of this taxon at series rank (spelled
Fruticosae
) by Adamson (1955) is to be treated as not validly published. The correct name for this taxon is series
Tetragonia
(Turland et al. 2018: ‘Art.
22.1.
The
name
of any subdivision of a genus that includes the
type
of the adopted, legitimate
name
of the genus to which it is assigned is to repeat that generic
name
unaltered as its epithet, not followed by an author citation.
’).
The species of
Tetragonia
subgenus
Tetragonia
are thus distributed among eight series as follows:
Tetragonia
L
.
,
Species plantarum 1: 480 (1753)
.
Type
:
T. fruticosa
L
., lecto., designated by
Britton,
Flora of
Bermuda
: 125 (1918)
.