Some distinctive new species of Psychotria (Rubiaceae, Psychotrieae) from Madagascar
Author
Taylor, Charlotte M.
Author
Gereau, Roy E.
Author
Schmidt, Heidi H.
text
Candollea
2020
2020-10-29
75
2
159
182
journal article
20368
10.15553/c2020v752a1
1b2f3915-6b17-4a42-9895-d8a11f37fd81
2235-3658
5724844
Psychotria davisiana
C.M. Taylor
,
sp. nov.
(
Fig. 2F–J
,
4
).
Holotypus
:
MADAGASCAR
.
Reg. Analamanga
[Prov.
Antananarivo
]:
Anjozorobe
,
Betatao
,
forêt de Vohitralongo
,
rte Anjozorobe-Ambatondrazaka
,
à
30 km
au NE de Betatao
,
18°04'07"S
47°58'41"E
,
950–1093 m
,
8.III.2000
,
Randrianaivo et al.
511
(
MO-6071774
!;
isotype
:
BR
,
G
[
G00341940
]!,
K
,
MO-6146891
!,
P
,
TAN
)
.
Psychotria davisiana C.M. Taylor
is distinguished from
P. haplantha Bremek.
by its larger leaf blades with acarodomatia, often shortly pedicellate flowers, longer calyx limbs, longer corollas, and endosperm that is at least shallowly ruminate on both abaxial and adaxial surfaces.
Shrubs
and small
trees
, collected in flower and fruit variously at
1–4 m
tall, much-branched, with well developed main stems bearing numerous branched lateral stems; stems weakly flattened when young becoming subterete, densely hirtellous to hispidulous with trichomes
0.2–0.5 mm
, pubescence deciduous with age.
Leaves
opposite;
petiole
0.1–0.5 cm
, glabrous;
blade
oblanceolate to elliptic, 0.6–4.5 ×
0.5–2 cm
, at base cuneate to acute, at apex obtuse to acute or weakly acuminate with tip to
2 mm
, drying papyraceous to chartaceous, on both surfaces glabrous; secondary veins 4 to 10 pairs, looping to interconnect near margins, usually with regularly developed small domatia comprising a pit and/or a tuft of strigose trichomes
0.1–0.3 mm
, usually with 1 intersecondary vein present between pairs of secondary veins, adaxially costa thickened to prominent, secondary veins plane to thickened, and remaining venation plane, abaxially costa prominent, secondary and tertiary veins plane to prominulous, and remaining venation not visible.
Stipules
interpetiolar, caducous, abaxially and marginally densely hispidulous to hirtellous with trichomes
0.2–0.5 mm
, adaxially glabrous in upper part and densely strigillose in lower part with trichomes
0.1–0.2 mm
, oblong to pandurate in outline,
1.2–7 mm
, lobed for 1/4–1/2 their length, basal portion (i.e., below lobes) ligulate to triangular or ovate, lobes lanceolate to narrowly triangular or linear, acute, erect when young then spreading laterally with age.
Inflorescences
terminal, reduced from a cyme to 1-flowered or shortly cymose and 2- or 3-flowered, enclosed by 1 pair of persistent stipules; bracts apparently reduced; pedicels
0.1–1 mm
.
Flowers
variously subsessile to pedicellate, 5-merous, distylous; hypanthium obconic to cylindrical, c.
1 mm
, glabrous to densely hirtellous with trichomes
0.3–0.5 mm
;
calyx
limb abaxially and adaxially glabrous, tubular portion
1–2 mm
, lobes narrowly ligulate to narrowly triangular,
1–2.5 mm
, acute to obtuse or rounded, marginally ciliate;
corolla
salverform, yellow, externally glabrous, tube cylindrical,
5– 8 mm
,
1.2–1.5 mm
diam. near middle, internally glabrous except densely pilosulous at stamen insertion in upper part of tube, lobes triangular,
2–2.5 mm
, acute, adaxially plane (i.e., not galeate), abaxially with conical thickening
0.5–1 mm
near tip;
stamens
in short-styled
form with
filaments
2–2.5 mm
, inserted in upper part of corolla tube, anthers c.
1.2 mm
, exserted, in long-styled
form not
seen;
style
in short-styled form c.
3 mm
with
stigmas
c.
1 mm
, included, in long-styled form c.
7.5 mm
with stigmas c.
1 mm
, exserted.
Infructescences
similar to inflorescences.
Fruits
subglobose, c.
5 mm
diam., sparsely hirtellous to glabrous, red, apparently juicy;
pyrenes
2, hemispherical, adaxially plane, abaxially smooth to weakly irregularly ridged or wrinkled; endosperm adaxially sparsely but deeply ruminate, abaxially sparsely shallowly ruminate.
Fig. 4. –
Psychotria davisiana
C.M. Taylor.
[
Antilahimena 6011
] [Photo: A.P. Antilahimena]
Etymology
. – The epithet of this species honors Dr. Aaron Davis, a
Rubiaceae
specialist who has documented and studied Malagasy
Psychotria
(
DAVIS et al., 2007
)
.
Habitat, distribution and phenology. –
Psychotria davisiana
has been collected in humid, usually dense evergreen forest at
950–1342 m
in central eastern
Madagascar
, and reportedly is often locally common. It has been collected with flowers in February, March, May, and June, and with ripe fruits in July and October.
Conservation status
. –
Psychotria davisiana
is known from
19 specimen
collections representing 19 unique occurrences in humid, usually dense evergreen forest at
950–1342 m
elevation. The EOO of the species is
2,705 km
², within the limits for “Endangered” under IUCN Red List Criterion
B1
; and the AOO is
44 km
², also within the limits for “Endangered” under Criterion B2 (
IUCN, 2012
). One occurrence is within the protected Anjozorobe Angavo forest corridor, one of the last vestiges of natural forests in
Madagascar
central highlands. The other 18 occurrences are in unprotected areas, one to the north and 17 to the south of the protected area. Forested areas without formal protection in the vicinity of Anjozorobe Angavo are subject to degradation by small-scale slash and burn agriculture and fire to create habitat for cattle farming (
GOODMAN et al., 2018
). The one occurrence to the north of Anjozorobe Angavo (at Vohitralongo Forest) constitutes one location (sensu
IUCN, 2012
) with respect to the known threats; the one within the protected area is a second location; the two isolated occurrences to the south constitute one location each; and the 15 collection sites from the Moramanga area, the site of a long-standing nickel mining operation, are a fifth location. Given the nature of three of the locations with general habitat degradation in unprotected sites and the remaining location in close proximity to on-going mining operations, causing a decline in AOO and number of mature individuals, the Red List status of
P. davisiana
is assessed as “Endangered” [EN B1ab(ii,iii,v)+2ab(ii,iii,v)].
Notes
. –
Psychotria davisiana
is characterized by its stems with smooth internodes and hirtellous pubescence; relatively small, obovate, abaxially glabrous leaves with small crypt-type domatia; hirtellous, rather small, caducous stipules that are bilobed for 1/3–1/2 of their length; terminal, subsessile to shortly pedunculate, solitary to three flowers subtended by a pair of persistent stipules; rather well developed, deeply lobed calyx limbs; medium-sized yellow corollas with the lobes abaxially bearing a conical projection; medium-sized red fruits; pyrenes that are smooth abaxially; and endosperm that is ruminate both abaxially and adaxially. The specimens seen dried brownish green or dark brown, with the dried trichomes dark reddish brown.
Psychotria davisiana
has a distinctive branching arrangement, with leafless principal stems bearing smaller, ascending, branched stems that do bear leaves. The acarodomatia are relatively small, and only one or two are developed on some leaves so these can be overlooked. On flowering branches, most of the stems bear inflorescences but few flowers are open at any time. Few long-styled flowers have been seen, and these were not dissected in order to preserve them. The style length is presented here following
BREMEKAMP (1963)
’s format and based on one flower, but it probably varies with corolla size to position the stigmas just above the top of the corolla tube. This is one of several
Psychotria
species
with relatively small leaves and the flowers borne singly or in small groups at the stem apices; only five such species were treated by Bremekamp, but this habit and flower presentation are now known from more species of
Psychotria
as well as some very similar species of
Gaertnera
Lam. (MALCOMBER & TAYLOR, 2009)
.
Psychotria davisiana
agrees with Bremekamp’s
Mapouria
Group VII, which is diagnosed in part by endosperm that is ruminate both adaxially and abaxially; the adaxial ruminations in
P. davisiana
are well developed, while the abaxial ones seen are small and can be overlooked.
Psychotria davisiana
is similar to
P. haplantha
Bremek.
, which can be separated by its branching pattern, with welldeveloped leafless stems bearing regularly spaced, short, unbranched, leaf-bearing stems; usually smaller leaf blades, 0.6– 1.4 ×
0.4–0.7 cm
, without domatia; subsessile flowers; shorter calyx limbs,
0.8– 1 mm
long; shorter corollas, with the tube
1.8 –3 mm
long; and endosperm that is entire or ruminate only adaxially. The fruits of
P. haplantha
were not seen by
BREMEKAMP (1963)
, but are now documented: these are red at mautiry, ellipsoid to subglobose, and c.
5.5 mm
in diameter, with two pyrenes that are smooth to weakly longitudinally ridged abaxially and endosperm weakly ruminate on the adaxial face (
Kotozafy 1006
, MO) (Bremekamp included
P. haplantha
in his
Psychotria
Group I, but he did not know the fruits are red so it does not agree with the characters of that group.)
Psychotria davisiana
keys to Bremekamp’s
Mapouria
Group VII, or if the abaxial seed ruminations are not noted to his
Mapouria
Group V; all of the species in both of those groups differ from
P. davisiana
in their branched inflorescences with more than three flowers.
Paratypi
.
–
MADAGASCAR
.
Reg. Analamanga
[Prov.
Antananarivo
]:
piste de Tsiazompaniry à Andapa
,
Andramasina
, [
19°16'00"S
47°59'00"E
],
VI.1961
,
Service Forestier
20291
(
MO
,
P
)
.
Reg. Alaotra-Mangoro
[Prov.
Toamasina
]:
Moramanga
,
Andasibe
,
Berano
,
Ambotavy forest
,
18°51'52"S
48°17'50"E
,
1018 m
,
3.III.2005
,
Antilahimena et al
. 3569
(
MO
,
P
,
TAN
n.v.)
;
Ambatovy
,
Sahaviana forest
,
18°51'37"S
48°17'10"E
,
976 m
,
14.II.2007
,
Antilahimena et al
. 5345
(
MO
,
TAN
)
;
Ambatovy
,
Andranovery forest
,
18°52'04"S
48°18'27"E
,
22.X.2007
,
Antilahimena
5886
(
MO
,
P
,
TAN
)
;
ibid. loco
,
18°51'55"S
48°18'35"E
,
993 m
,
10.II.2008
,
Antilahimena
6011
(
MO
,
P
,
TAN
)
;
ibid. loco
,
18°52'12"S
48°18'34"E
,
1003 m
,
15.II.2008
,
Antilahimena
6055
(
MO
,
P
,
TAN
)
;
Ambatovy
,
côté SE de Berano
,
18°49'18"S
48°17'04"E
,
1046 m
,
13.X.2008
,
Miandrimanana
389
(
MO
,
TAN
)
;
Ambatovy
,
côté Ampitambe
,
18°49'17 "S
48°17 '09"E
,
1011 m
,
13.X.2008
,
Miandrimanana
398
(
MO
,
P
,
TAN
)
;
ibid. loco
,
18°51'49"S
48°18'39"E
,
988 m
,
10.II.2008
,
Rakotondrafara et al.
542
(
MO
,
TAN
)
;
ibid. loco
,
18°51'53"S
48°18'36"E
,
14.II.2008
,
Rakotondrafara et al.
622
(
MO
,
P
,
TAN
)
;
ibid. loco
,
18°50'47"S
48°17'18"E
,
1020 m
,
4.III.2005
,
Rakotovao et al.
1486
(
MO
,
P
,
TAN
)
;
ibid. loco
,
18°49'34"S
48°17'14"E
,
1058 m
,
25.X.2011
,
Rasoazanany et al.
29
(
AVY
,
MO
,
P
,
TAN
)
;
ibid. loco
,
18°51'05"S
48°18'13"E
,
1080 m
,
15.X.2005
,
Razanatsoa et al
. 530
(
K
,
MO
,
P
,
TAN
)
;
Phelps-Dodge project site
, c.
15 airkm NE of Moramanga
, c.
11 km
E of Antanambao
,
18°50'16"S
48°21'14"E
,
950 m
,
4.III.1997
,
Rakotomalaza et al
. 1231
(
MO
,
P
,
TEF
)
;
Ambongabe
,
Sahamorandro
,
18°39'30"S
47°57'59"E
,
1342 m
,
8.IV.2005
,
Rakotonirina et al
. 240
(
MO
,
P
,
TAN
)
;
Ambatovy
,
Ankosy
,
18°48'41"S
48°17'45"E
,
1071 m
,
31.VII.2012
,
Ramahenina et al.
85
(
MO
,
P
,
TAN
)
;
Andasibe
,
Berano
,
Ampanadiofanantsy forest
,
18°51'46"S
48°16'31"E
,
983 m
,
27.X.2008
.
Randrianasolo et al.
983
(
MO
,
TAN
)
;
massif de l’Ifody
,
rive droite du Mangoro
, [
18°55'S
48°03'E
],
29.V.1966
,
Service Forestier
24803
(
MO
,
P
)
.