Notes on miscellaneous Acacia species from Tropical Africa

Information relating to a number of miscellaneous  Acacia species from tropical Africa, is pre­sented. Two new species,  A. manubensis and  A. pseudonigrescens , are described.

Chevalier 8992 and 9050 from the C entral African Republic, the syntypes o f A. etbaica Schweinf. var. hirta A. Chev., in Bull. Soc. Bot. Fr. 74: 959 (1927), are housed in the Paris herbarium and both are flowering specimens.The young branchlets are pubes cent, the bark is reddish-brow n and flaking minutely, and the paired stipular spines are straight and up to 1 cm long.The leaves have up to 14 pinnae pairs and the petioles, rhachides and rhachillae are sparingly to fairly densely pubescent.The leaflets are in up to 24 pairs per pinna, up to 3,75 x 1 mm, discolorous, glabrous ap art from the conspicuous m arginal cilia.The flowers are in round heads on fairly densely pubes cent peduncles, and the involucels are up to one-third o f the way up the peduncle.The calyx is pubescent apically, while the corolla is glabrous.

ACACIA FISCHERI HARMS
The two syntypes o f A. fischeri H arm s, in Bot. Jahrb. 51: 365 (1914), namely, Fischer 157 and Stuhlmann 672 from Tanzania, were both destroyed in the Berlin herbarium during the last war.and all attem pts to trace isosyntypes have so far proved fruitless.In the British M useum (N atural History) there is a sketch o f the Berlin specimen o f Fischer 157, but unfortunately the sketch is rather poor and does not really enable the species to be identified.In the British M useum, however, there is also a

E.
G. Baker, in J. Bot. 66, Suppl. Polypet: 156 (1928), based his description o f A. gossweileri on Gossweiler 1740 from Angola.The young branchlets o f Gossweiler 1740 are arm ed with paired, broadbased.recurved prickles and the lower surfaces o f the leaf-petioles, rhachides and some o f the rhachillae are arm ed with num erous scattered, yellowish, recurved prickles up to 2 .5 mm long.The petioles, rhachides and rhachillae are sparingly to densely clothed with a slightly golden, spreading indum entum .The petioles have a small gland on the upper surface and the rhachides have a small gland at the ju nction o f the top 1-4 pinnae pairs.The leaves have up to 10 pinnae pairs and up to 16 leaflets per pinna.The leaflets on the holotype in the British M useum (N atu ral H istory) are all fairly uniform and are up to 6 x 2 mm, but on the isotype in the Kew herbarium , one leaf is much larger than the others and bears larger leaflets which are up to 10 x 3 ,5 mm.The leaflets are m ostly linear-oblong or oblong, slightly falcate, asym m etric basally, rounded to subacute apically, discolorous, with a som ew hat prom inent venation beneath, with ciliate m argins and pubescence on the proxim al side of the m idrib on the lower surface, especially basally.The inflorescence axes are up to 9 cm long (including the peduncle) and are sparingly clothed with spreading hairs.The flowers are sessile o r alm ost so and the calyces and corollas are glabrous.
Gossweiler 1740 falls within the range o f variation o f A. goetzei H arm s. A. goetzei is extremely variable vegetatively, especially in the indum entum and in leaflet shape and size, and the arm atu re o f the leafrhachis is also variable.As the leaflets in Gossweiler 1740 are m ostly less than 3 mm wide and are oblong o r linear-oblong, as the leaf-rhachides are arm ed, and as there is a small gland at the junctio n o f the top 1-4 pinnae pairs, A. gossweileri is referred to synony my under A. goetzei subsp.microphylla Brenan.
A. goetzei Harms subsp.microphylla Brenan in Kew Bull. 11: 204 (1956).T ype: M alawi, M om bera district, N jakw a to F o rt Hill, Greenway 6393 (K , holo.!).Brux. 55 B: 311 (1935), is housed in the Jardin N atio nal de Belgique Bruxelles and consists o f tw o twigs.The left-hand twig, which is the larger, bears flowers and pods, while the right-hand specimen bears flowers only.Some o f the spinescent stipules on each twig are fused basally into deep reddish-brow n to purplish, dh round " ant-galls" up to 3 ,5 cm in diam eter.The bark on the twigs is yellowish and split transversely irregularly.The leaves are glabrous, have up to 12 pinnae pairs and the leaflets are glabrous th roughout or m inutely ciliate.The peduncles are glabrous and the involucels are basal.The flowers are whitish, the calyces are glabrous and up to 1,5 mm long, and the corollas are glabrous and up to 4 mm long.The pods are falcate, finely longitudinally venose, glabrous, atten u ate at both ends and up to 5 mm wide.ACACIA M ACALUSOI MATTEI M attei, in Boll. O rto Bot. G iard. Col. Palerm o 7: 94 (1908), based his description o f A. macalusoi on Macaluso 65 from G ium bo in the Somali Republic.U nfortunately it has not been possible to locate Macaluso 65.The specimen is thought to be housed in the Instituto Botanico di Palerm o, but attem pts to trace it have been unsuccessful.C onsequently the identity o f A. macalusoi rem ains in some doubt.

A. gossweileri
Chiovenda, in Ann.Bot., R om a 13: 392 (1915), m entions having received the type specimen on loan.He found that there were two specimens m ounted on the sheet o f Macaluso 65, a flowering twig and a fruit ing twig, and noted th at the two twigs belonged to two different species, the flowering twig being very closely allied to A. Senegal (L.) Willd..Because o f this mixed gathering, Chiovenda excluded the flowering twig from A. macalusoi and am ended the description o f the species accordingly, the fruiting twig thus becoming the lectotype o f the species.Owing to the paucity o f the fruiting twig, C hiovenda was unable to establish to which species A. macalusoi was most closely allied, but he concluded th at it was not allied to A. Senegal.Subsequently, Chiovenda, FI. Som ala 2: 186, fig. 113 (1932), referred Senni 135 and 152 to A. maca lusoi, fig.113 being based on the latter specimen.These two specimens were received on loan from the H er barium U niversitatis Florentinae.Both are very poor fruiting specimens but they are apparently members o f the A. goetzei H arm s complex.As the rem ains o f the calyces (just visible at the point o f attachm ent of the pods) are sparingly puberulous, the specimens are thought possibly to be referable to A. rovumae Oliv., but the material is too poor for one to come to any definite conclusion.If the two specimens m atched the type specimen o f A. macalusoi, then there is a distinct possibility that A. macalusoi is not a good species.
On account o f the paired prickles, spicate inflores cences and flowers with glabrous calyces, A. manubensis falls within the A. goetzei H arm s-A.nigrescens Oliv.complex.It differs from A. goetzei in having different leaflets and smaller pods, from A. nigrescens in having m ore num erous and sm aller leaflets and sm aller pods, and from both o f these species in having yellowish, papery, peeling bark.
A. nianubensis is known only from the type collec tion.M ore m aterial is desired.

I
am grateful to M r H. K. Airy Shaw for checking the Latin description.

Pod unknow n.
A. pseudonigrescens bears a strong superficial re semblance to A. nigrescens Oliv., but is readily distinguishable from the latter in having a sm ooth, grey, powdery bark, a densely pubescent calyx, an appressed-pubescent corolla, a pubescent ovary, a petiole with a large, flattened or ± depressed, discoid or elongate gland situated a short distance above the pulvinus, and finely appressed-puberulous leaflets with several conspicuous basal nerves arising from the point o f attachm ent.In A. nigrescens the leaflets have a distinct m idrib and prom inent lateral ner\es, al though occasionally there are also a few relatively inconspicuous basal nerves.In A. pseudonigrescens, however, there is often no conspicuous m idrib, but rather a num ber o f prom inent basal nerves arising from the point o f attachm ent o f the leaflet.The leaflets in A. pseudonigrescens are finely appressed-puberulous on both surfaces, while in A. nigrescens the leaflets are either glabrous throughout or sometimes they are clothed with semi-erect hairs above an d /o r below.Leaflet size and shape in the two species are similar, but the texture differs, the leaflets in A. pseudonigres cens being more coriaceous.
A lthough Gilbert 2129 is unarm ed, it is anticipated that further collections o f this species may be arm ed with paired prickles.It will be recalled that A. nigres cens is occasionally unarm ed.
In addition to the above m orphological differences between A. pseudonigrescens and A. nigrescens, a large geographical discontinuity separates the two species, A. nigrescens not being recorded further north than Tanzania.

ACACIA SEYAL DEL.
In the past A. seyal has often been confused with A. hockii De W ild., but, although the two are closely related, they are considered to be distinct species.A. hockii differs from A. seyal chiefly by having a non-pow dery bark.The twigs are usually (but not always) m ore elongate and slender, with a reddish or brownish bark which does not peel to expose the inner layer as, so characteristically, does the bark of A. seyal, while the young branchlets are usually clothed with a m ore o r less dense puberulence which is absent in A. seyal.A. stenocarpa H ochst. ex A. Rich., Tent. FI. Abyss. 1: 238 (1847), has frequently been m isinter preted in the past and often confused with A. hockii De Wild.It was therefore o f great interest to find two sheets o f Schimper 1948 from Ethiopia, the type num ber o f A. stenocarpa, in the Paris herbarium .U n fortunately the m aterial on each o f the sheets is rather poor, one sheet consisting o f a small flowering twig and a fruiting twig, and the other o f a small fruiting twig, two pods and sterile fragm ents.However, they do enable the species to be identified.
The young branchlets are sparingly puberulous and arm ed with slender, paired, stipular spines up to 6 cm long.The epiderm is o f the branchlets is brow n, flaking off to reveal a powdery, yellowish inner layer, and the leaves have 2 -6 pinnae pairs and 9-14 leaflets per pinna.The leaflets have inconspicuous lateral nerves and are glabrous except for the ciliolate m ar gins.The peduncles are glabrous o r have few scattered hairs, and the involucels are alm ost at o r below the middle o f the peduncle.The calyx is inconspicuously pubescent above and the corolla is glabrous.The pods are linear, falcate, up to 11 cm long and 0 ,6 cm wide, finely longitudinally striate, glabrous ap art for some sessile glands, and longitudinally dehiscent.Burtt Davy, in Kew Bull. 1930: 404 (1930), stated that the type specimen o f A. tortilis var.pubescens Aylmer ex Burtt Davy, namely, Aylmer X8 from kilo 8 on M edani railway, K hartoum , Sudan, was housed in the Kew herbarium , but all efforts to trace this specimen have failed.O f the other three specimens cited and determ ined by Burtt Davy as var.pubescens, only Muriel S/9 and Letourneux 257 have been located.Muriel S/9 from the Blue Nile near W adi M edani is now selected as the neotype o f var.pubescens.Choice o f a neotype for var.pubescens is to some extent academ ic, because var.pubescens Aylm er ex Burtt Davy is a later hom onym and synonym o f A. tortilis var.pubescens A. Chev. in Bull. Soc. Bot. Fr. 74: 960 (1927), the latter now being A. tortilis subsp.raddiana (Savi) Brenan var.pubescens A. Chev.

ACACIA V ER RUG ERA SCHWEINF. VAR. SU BIN E R M IS
A. CHEV.Chevalier, in Bull. Soc. Bot. Fr. 74: 959 (1927), based his description o f A. verrugera var.subinermis on Chevalier 7598 from the C entral African Republic.The holotype in the Paris herbarium is a flowering specimen.The young branchlet is yellowish, glabrous or nearly so, and, as the varietal epithet implies, unarm ed.The leaves have up to 18 pinnae pairs and up to 35 leaflets per pinna.The leaflets are narrow ly oblong, up to 5 x 1 mm, rounded apically, glabrous throughout or with few small, m arginal cilia.The involucels are apical.
Chevalier 7598 is clearly referable to A. sieberana DC.The absence o f stipular spines is not considered to be w orthy o f taxonom ic recognition, and.as the young branchlet is ± glabrous, Chevalier 7598 is referred to A. sieberana var.sieberana.A. verrugera var.subinermis is now reduced to synonymy. A.
flowering specimen o f A. fischeri, namely, B. D. Burtt 1131 from near Salia in the K ondoa district o f Tanzania.It carries the com m ent " Det. in Dahlem Herb.5/12/ 1928 by D r H arm s & B.D.B."In the absence o f any isosyntypes, Burtt 1131 in the British Museum is selected as the neotype o f A. fischeri.ACACIA GOSSWEILERI BAK.F.