Chamaecrista mwangokae (, ), a New from the Southern Highlands of Tanzania

Roy E. Gereau and Gretchen M. Walters Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166-0299, U.S.A. [email protected]; [email protected]

ABSTRACT. We discuss the historical usage of the sion of the New World species by Irwin and genus Chamaecrista (Fabaceae, Caesalpinioideae) Barneby (1982), Lock (1988) provided most of the in Africa, describe and illustrate the new species remaining combinations needed for African spe- C. mwangokae from southern Tanzania, reduce C. cies. The tropical African species now included in hildebrandtii to taxonomic synonymy under C. zam- Chamaecrista (Lock, 1989) may be differentiated besica, and provide a key to the East African spe- from and by the following key, based cies of Chamaecrista with stipitate petiolar glands. on the key to species of Cassia sensu lato by Bren- Key words: Caesalpinioideae, Chamaecrista, an (1967: 51–58) with additional characters from Fabaceae, Tanzania. Irwin and Barneby (1982: 2–3), Polhill and Thulin (1989: 50), and Thulin (1993: 343).

Within Fabaceae subfamily Caesalpinioideae, Ir- 1a. Petioles and rhachides of leaves eglandular. win and Barneby (1982) placed Cassia L., Cha- 2a. Filaments of 2 or 3 lower stamens with an maecrista Moench, and Senna Miller in tribe Cas- S-shaped curve above base, their anthers in- sieae, subtribe Cassiinae. Chamaecrista is a genus trorsely dehiscent by slits; legume indehis- cent, cylindrical or slightly compressed, 20– of approximately 330 species (G. P. Lewis, pers. 90 cm long ...... Cassia comm.), with greatest diversity in Central and South 2b. Filaments of all stamens straight or in- America and a secondary center of diversity in curved, their anthers terminally dehiscent tropical Africa (Polhill & Thulin, 1989; Thulin, by slits or pores; legume dehiscent, flat- tened, or winged or ridged along each valve, 1993; Du Puy & Rabevohitra, 2002). Although almost always Ͻ 20 cm long (almost cylin- Meyer (in Meyer & Dre`ge, 1836) followed the ge- drical and longer in the frequently intro- neric concept of Moench (1794) and named a num- duced Senna spectabilis (DC.) H. S. Irwin & ber of new South African species in Chamaecrista, Barneby). the vast majority of African regional floristic treat- 3a. Leaflets in 2 pairs; stem with glandular- based bristles; seeds without areoles .. ments of Fabaceae predated the formal reinstate- ... Chamaecrista absus (L.) H. S. Irwin & ment of the genus in the New World by Irwin and Barneby Barneby (1982). Thus most of the well-known Af- 3b. Leaflets in 3 or more pairs; stem without rican floristic authors of the 19th (e.g., Harvey, glandular-based bristles; seeds usually with areoles ...... Senna 1862; Oliver, 1871) and 20th centuries (e.g., Stey- 1b. Petioles and/or rhachides of leaves with conspic- aert, 1952; Keay, 1958; Brenan, 1967; Aubre´ville, uous glands (extrafloral nectaries). 1968, 1970) treated Chamaecrista as part of a very 4a. Leaflets with a short but distinct petiolule; broadly circumscribed Cassia, a circumscription glands of petiole or rhachis mounded or maintained even later by Lebrun and Stork (1992). elongate, secreting nectar from a convex sur- face; pedicels ebracteolate; sepals obtuse or In the 20th century only Polhill and Thulin (1989) rounded at apex; legume indehiscent or and Thulin (1993) recognized Chamaecrista in slowly dehiscent, the valves never twisting; tropical African floristic treatments, followed in the seeds usually with areoles ...... Senna present century by Du Puy and Rabevohitra (2002) 4b. Leaflets sessile or with a short pulvinulus; glands of petiole or rhachis cup-shaped or for Madagascar. flat, sometimes stipitate, secreting nectar Greene (1897) laid the foundation for a world- from a concave or flat surface; pedicels with wide circumscription of Chamaecrista and soon af- 2 bracteoles near or above middle; sepals terward (1899) began the transfer of African spe- acute or acuminate at apex; legume elasti- cies of Cassia to Chamaecrista. Standley (1917) cally dehiscent with twisting valves; seeds without areoles ...... Chamaecrista followed with a few more new combinations in Cha- maecrista, but without reference to Greene or pro- Under ‘‘Cassia sp. A,’’ Brenan (1967: 84) de- viding any further explanation. Following the revi- scribed, but did not formally name, a distinctive

NOVON 13: 438–442. 2003. Volume 13, Number 4 Gereau & Walters 439 2003 Chamaecrista mwangokae from Tanzania

Chamaecrista from Mufindi District in the Southern trict, Ikanga near Mdabulo, 8Њ30ЈS, 35Њ31ЈE, 26 Aug. Њ Ј Њ Ј Highlands of Tanzania. Recent collections made 1952, W. Carmichael 110 (K); Sao Hill, 8 30 S, 35 15 E, 1800 m, 16 Oct. 1987, J. Lovett, P. A. Keeley & M. S. during inventories conducted by the Tanzania Keeley 950 (K, MO); Irundi, ca. 8Њ27ЈS, 35Њ15ЈE, 1830– Forest Conservation Group, an environmental NGO 1980 m, 19 Sep. 1971, C. F. Paget-Wilkes 952 (MO); Irun- based in Dar es Salaam, included material un- di Hill, Sao Hill, ca. 8Њ27ЈS, 35Њ15ЈE, 1980 m, Dec. 1963, questionably corresponding to Cassia sp. A, al- J. Procter 2469 (K); ‘‘Mufindi,’’ 1830 m, Oct. 1931, R. R. Staples 232 (K). though the material designated below as the type of the new species lacks additional stipitate glands The new species is known only from the above- on the leaf rhachis. cited specimens from Mufindi District in Iringa Re- gion, southern Tanzania; J. M. Lock (pers. comm.) Chamaecrista mwangokae Gereau & G. M. Wal- has confirmed that there are no specimens of Cha- ters, sp. nov. TYPE: Tanzania. Iringa Region, maecrista mwangokae at K from the Flora Zam- Mufindi District: public land between Mdabulo besiaca area. Its conservation status must be con- and Igoda Villages along road to Luhunga Vil- sidered as data deficient, although more recent lage, 8Њ30Ј40ЉS, 35Њ30Ј02ЉE, 1675 m, 20 Oct. collections (not examined) may allow more precise 2000, M. A. Mwangoka 1741 (holotype, NHT; evaluation. From collectors’ field notes, Chamae- isotypes, BRIT, K, MO, S, tfcg (reference col- crista mwangokae occurs in grassland and stony lection of Tanzania Forest Conservation grassy hillsides, associated with Aloe (Asphodela- Group)). Figure 1. ceae), Apodytes dimidiata E. Meyer ex Arnott (Ica- cinaceae), Asparagus (Asparagaceae), Dodonaea Haec species inter congeneros Africae orientalis glan- dulis petiolaribus stipitatis praeditos ad Chamaecristam viscosa Jacquin (Sapindaceae), Faurea (Protea- grantii et C. zambesicam quoad foliolorum costam excen- ceae), Helichrysum (Asteraceae), and Protea (Pro- tricam sed non submarginalem maxime accedit, sed ab eis teaceae). The new species is nearly always found foliolorum venatione valde reticulata atque petalis 14–18 in recently burned areas; unsuccessful attempts to mm longis distinguitur. locate it in unburned areas in October 2002 may Perennial herb with thick woody rootstock; stems indicate that C. mwangokae is dependent upon fire spreading or ascending, 10–30 cm long, sparsely for induction of flowering. hirsute to glabrous. Stipules acuminate, parallel- The specific epithet commemorates the collector veined, (3.0–)3.9–9.0 ϫ 1.0–2.0 mm; petiole (3–) of the type, Moses Anyelwisye Mwangoka, whose 5–7 mm long; leaf rhachis channeled above, collections under the direction of the Tanzania For- (1.0–)2.0–4.5(–5.8) cm long; gland on petiole just est Conservation Group have been of exceptional below lowest leaflet pair, occasionally with addi- value to the taxonomic and phytogeographic study tional glands along rhachis between upper leaflet of the Eastern Arc Mountains of Tanzania. pairs, stipitate, the stipe (0.2–)0.4–1.5 mm long, During study of other East African species of the head (0.2–)0.3–0.4(–0.8) mm wide; leaflets in Chamaecrista with stipitate petiolar glands, careful 2 to 11 pairs, glabrous except for frequently ciliate examination of type specimens and available her- margins and costa, asymmetrically elliptic with barium material formerly assigned to C. hildebrand- proximal margin rounded, distal margin straight tii (Vatke) Lock and C. zambesica (Oliver) Lock re- and parallel to strongly excentric costa, largest leaf- vealed no consistently reliable means of ϫ lets 9.5–12.0(–17.0) (2–)4–8 mm; costa (0.3–) distinguishing these species. Brenan (1967: 84–85) 0.9–1.7(–2.5) mm from distal margin; secondary primarily distinguished these species on the basis veins parallel only in basal half, branched and re- of stipe length: 0.3–0.7 mm for C. hildebrandtii and ticulate in distal half; tertiary venation strongly re- 1.00–1.25 mm for C. zambesica. Our actual mea- ticulate on both surfaces. Inflorescence 1- or 2- surements of stipes showed a nearly continuous flowered; pedicels (2.4–)3.8–6.2(–9.4) cm long; gradation between 0.1 and 1.3 mm. With no con- bracteoles cordate, acute, located in uppermost ⅓ sistent morphological distinction and overlapping to 1 of pedicel, 3.0–5.1 ϫ 0.9–2.0 mm. Sepals ⁄10 geographic ranges, we here synonymize these two ϫ bright red in living material, (3–)9–13 2.0–4.1 species under the older binomial. (–5.0) mm; petals yellow, 14–18 ϫ 9–11 mm; sta- mens 10, the anthers 0.3–0.8 mm long; ovary densely pubescent. Mature legume not seen; im- Chamaecrista zambesica (Oliver) Lock, Kew mature legume pubescent, ca. 4.5 cm long; seeds Bull. 43: 338. 1988. Basionym: Cassia zam- unknown. besica Oliver, Fl. Trop. Afr. 2: 280. 1871. TYPE: Mozambique. Shamwara, Kirk s.n. (ho- Paratypes. TANZANIA. Iringa Region: Mufindi Dis- lotype, K). 440 Novon (K). C. grantii, G. P. Leedal 1164 (MO). —F. Leaflet pair of C. zambesica, M. E. Archbold 1016 Gereau & G. M. Walters. A–C drawn from isotype. —A. , habit. —B. Apex of petiole with petiolar gland and basal leaflet pair. Chamaecrista mwangokae Figure 1. —C. Open flower, frontal view. —D. Immature fruit. —E. Leaflet pair of Volume 13, Number 4 Gereau & Walters 441 2003 Chamaecrista mwangokae from Tanzania

Chamaecrista hildebrandtii (Vatke) Lock, Kew Bull. 43: 7.5 mm long ...... 336. 1988. Syn. nov. Basionym: Cassia hildebrandtii ..C. fenarolii (Mendonc¸a & Torre) Vatke, Oesterr. Bot. Z. 30: 80. 1880. TYPE: Kenya. Lock Teita Dist., Ndara Hill, Hildebrandt 2464 (holotype, 7b. Stipitate glands sometimes B†; isotype, K). present in lower part of petiole and/or on rhachis between low- Selected specimens. UGANDA. E Ankole Dist.: er pairs of leaflets; stipe of Nyakatokye-Buyene, Kashari, 0Њ22ЈS, 30Њ31ЈE, 1680 m, gland 0.25–0.75 mm long; pet- 17 Mar. 1986, P. K. Rwaburindore 2245 (MO). RWANDA. als 8–10 mm long ...... Biumba, Re´gion de Mutara, env. Mimuli, colline Ruten- .... C. katangensis (Ghesquie`re) gura, 1400–1450 m, 8 Oct. 1959, G. Troupin 11811 (MO). Lock KENYA. Kiambu Dist., Muguga North, 2040 m, 15 Oct. 1953, B. & L. D. Verdcourt 1022 (MO). TANZANIA. Kil- Acknowledgments. We thank N. Doggart of the imanjaro Region: Same Dist., S Pare Mountains, Suji Tanzania Forest Conservation Group for adminis- Village, Hekano, 4Њ21Ј35ЉS, 37Њ51Ј20ЉE, 1480 m, 31 Mar. 1999, J. A. Mlangwa 116 (MO, NHT). Pwani Region: trative and logistical support, K. Doody for field- Kisarawe Dist., Mkamba, ca. 70 km SW of Dar es Salaam, work, G. P. Lewis of the Royal Botanic Gardens, 70 m, 4 June 1972, B. Mhoro & V. F. Malima DSM 2588 Kew, for data on species numbers and the loan of (DSM, MO). herbarium specimens, J. M. Lock of Kew for assis- tance in specimen identification, and Y. Wilson- KEY TO EAST AFRICAN SPECIES OF CHAMAECRISTA WITH Ramsey for the fine illustration. STIPITATE PETIOLAR GLANDS

1a. Leaflets with costa excentric but not submargin- Literature Cited al, (0.3–)0.5–2.5 mm from distal margin. 2a. Leaflets with secondary veins branched and Aubre´ville, A. 1968. Le´gumineuses–Caesalpinı¨oide´es. In: reticulate in distal half and tertiary venation A. Aubre´ville (editor), Flore du Gabon 15: 1–362. Mu- strongly reticulate; petals 14–18 mm long se´um National d’Histoire Naturelle, Paris...... C. mwangokae Gereau & G. M. Walters . 1970. Le´gumineuses–Caesalpinı¨oide´es. In:A. 2b. Leaflets with secondary venation parallel Aubre´ville (editor), Flore du Cameroun 9: 1–339. Mu- nearly to margin and tertiary venation incon- se´um National d’Histoire Naturelle, Paris. spicuous; petals 4–14 mm long. Brenan, J. P. M. 1967. Leguminosae Subfamily Caesalpi- 3a. Stipitate glands present on leaf rhachis nioideae. In: E. Milne-Redhead & R. M. Polhill (edi- between some or all pairs of leaflets in tors), Flora of Tropical East Africa. Crown Agents for addition to petiolar gland; petals 10–14 Oversea Governments and Administrations, London. mm long .... C. grantii (Oliver) Standley Du Puy, D. J. & R. Rabevohitra. 2002. Tribe Cassieae. 3b. Stipitate gland present only on petiole, Pp. 60–103 in D. J. Du Puy, J.-N. Labat, R. Rabevoh- rarely sessile or subsessile glands pre- itra, J.-F. Villiers, J. Bosser & J. Moat, The Legumino- sent on rhachis between pairs of leaf- sae of Madagascar. Royal Botanic Gardens, Kew. lets; petals 4–12 mm long ...... Greene, E. L. 1897. The genus Chamaecrista. Pittonia 3: ...... C. zambesica (Oliver) Lock 238–243. 1b. Leaflets with costa marginal or submarginal, 0– . 1899. Early specific types in Chamaecrista. Pit- 0.4 mm from distal margin. tonia 4: 25–32. 4a. Petiolar gland with stipe 1.0–2.2 mm long; Harvey, W. H. 1862. Leguminosae. In W. H. Harvey & O. pedicel 3–6 mm long ...... W. Sonder, Flora Capensis 2: 1–285. Hodges, Smith, ...... C. fallacina (Chiovenda) Lock Dublin, and A. S. Robertson, Capetown. 4b. Petiolar gland with stipe 0.1–0.8 mm long; Irwin, H. S. & R. C. Barneby. 1982. The American Cas- pedicel 9–30 mm long. siinae. Mem. New York Bot. Gard. 35: iv–v, 1–918. 5a. Leaf rhachis crenate-crested; petals Keay, R. W. J. 1958. Flora of West Tropical Africa (ed. 2, 3.0–5.5 mm long ...... revised), Vol. 1(2). Crown Agents for Oversea Govern- ...... C. gracilior (Ghesquie`re) Lock ments and Administrations, London. 5b. Leaf rhachis channeled; petals 7–10 Lebrun, J.-P. & A. L. Stork. 1992. E´ nume´ration des plan- mm long. tes a` fleurs d’Afrique tropicale, Vol. 2. Conservatoire et 6a. Leaflets in 4 to 13 pairs; pedicel Jardin botaniques de Gene`ve. with appressed pubescence; petals Lock, J. M. 1988. Cassia sens. lat. (Leguminosae–Caesal- yellow, orange, or red at base; le- pinioideae) in Africa. Kew Bull. 43: 333–342. gume 1.2–3.3 cm long ...... 1989. Legumes of Africa: A Checklist. Royal Bo- ...C. usambarensis (Taubert) Standley tanic Gardens, Kew. 6b. Leaflets in 11 to 43 pairs; pedicel Meyer, E. H. F. & J. F. Dre`ge. 1836. Commentariorum de with pubescence short and dense, plantis Africae australioris, Fasc. 1. Leipzig. not appressed, or with trichomes 1– Moench, C. 1794. Methodus plantas horti botanici et agri 2 mm long perpendicular to pedi- marburgensis. Marburg. cel; petals yellow; legume 2.5–5.0 Oliver, D. 1871. Caesalpinieae. In: D. Oliver, Flora of cm long. Tropical Africa 2: 258–321. L. Reeve, London. 7a. Stipitate gland present only at Polhill, R. M. & M. Thulin. 1989. Caesalpinioideae. In: apex of petiole; stipe of gland I. Hedberg & S. Edwards (editors), Flora of Ethiopia 3: 0.1–0.2 mm long; petals 7.0– 49–70. The National Herbarium, Addis Ababa Univer- 442 Novon

sity, and Department of Systematic Botany, Uppsala Flore du Congo Belge, Flore du Congo Belge et du Ru- University. anda-Urundi 3: 496–545. I.N.E´ .A.C., Brussels. Standley, P. C. 1917. New East African . Smithson- Thulin, M. 1993. Fabaceae (Leguminosae). In M. Thulin ian Misc. Collect. 68(5): 1–20. (editor), Flora of Somalia 1: 341–465. Royal Botanic Steyaert, R. 1952. Cassieae. In: Comite´ exe´cutif de la Gardens, Kew.