New combinations in Senegalia and Vachellia ( Leguminosae : Mimosoideae ) for Southeast Asia and China

Fragmentation of the former broadly circumscribed genus Acacia (Leguminosae: Mimosoideae) necessitates combinations in Senegalia (syn. Acacia subg. Aculeiferum) and Vachellia (syn. former Acacia subg. Acacia) for the following 40 taxa that are recorded for the region encompassed by Southeast Asia and China. Senegalia andamanica, S. borneensis, S. caesia, S. comosa, S. delavayi, S. delavayi var. kunmingensis, S. donnaiensis, S. gageana, S. intsia, S. kekapur, S. kostermansii, S. meeboldii, S. megaladena, S. megaladena var. garrettii, S. megaladena var. indochinensis, S. merrillii, S. palawanensis, S. pennata subsp. hainanensis, S. pennata subsp. insuavis, S. pluricapitata, S. pluriglandulosa, S. pruinescens, S. pseudointsia, S. sulitii, S. tawitawiensis, S. teniana, S. thailandica, S. tonkinensis, S. torta, S. verheijenii, S. vietnamensis and S. yunnanensis. Vachellia harmandiana, V. inopinata, V. kingii, V. leucophloea, V. leucophloea var. microcephala, V. myaingii, V. siamensis (syn. Acacia craibii) and V. tomentosa. Senegalia rugata replaces the well-known name Acacia concinna. There are four doubtful names for the region, namely, Acacia brunnescens, A. microcephala, A. obcordata and A. pseudoarabica.

The present paper provides combinations for the indigenous taxa of Southeast Asia and China that are referable to Sene galia and Vachellia.This is not a taxonomic revision of these two genera.In undertaking this work we have relied on previous relevant studies of Acacia s.lat., the most important being those of the late Ivan Nielsen (Nielsen 1980(Nielsen , 1981(Nielsen , 1985a(Nielsen , b and 1992) ) for Southeast Asian taxa and Wu De-Lin & Nielsen (2010) for those from China.Unless otherwise indicated, all new combinations presented here apply to taxa that were accepted as current under Acacia in these publications.Full synonymy (under Acacia) for these taxa is given in the above references, and in Roskov et al. (2005, which extensively cites the works of Nielsen).The only synonyms included here are basionyms and names that were accepted as current under Acacia in the above works.We have also noted cases where taxonomic opinion differs from that which we have adopted.
Apart from the 40 new combinations presented here, the only indigenous taxa of Vachellia and Senegalia in Southeast Asia and China are the following: S. catechu (L.f.) P.J.H. Hurter & Mabb., S. chundra (Roxb. ex  Unless otherwise indicated, type information for most taxa has been taken from Nielsen (1980Nielsen ( , 1981Nielsen ( , 1985a)); in the remaining cases the type citation from the protologue is provided.Type specimens have not been checked by the authors.Distributions given below are taken from Roskov et al. (2005) and Wu De-Lin & Nielsen (2010) unless otherwise stated.
The geographic scope of this paper includes Southeast Asia and southern China.As used here the term Southeast Asia is the area extending from Myanmar (Burma), Vietnam, Laos, Cambodia and Thailand to the Malesian region as defined by Van Steenis (1948).
Note -As discussed by Nielsen (1980: 349) the entities described as A. rugata and A. concinna have at times been treated as separate species or as varieties of the one species, but he considered that they are conspecific and correctly applied the name A. concinna to the combined entity.Under Senegalia, however, the correct name for this entity is S. rugata.It is regrettable that the well-known epithet concinna must be replaced, however, it may possibly be reinstated in the future if studies show that it is best to recognize two taxa for what is here called S. rugata.
Note -Varieties are recognized for this species in ILDIS (Roskov et al. 2005), based on Kumar & Sane (2003: 89), therefore, combinations in Vachellia are provided here.However, it is noted that in the latter publication the authors' note that the variety is "not maintained in recent literature", citing Chakrabarty & Gangopadhyay (1996) as their validating reference.
Note -This name is presumably homotypic with Mimosa tomentosa Rottler.
Acacia microcephala Graham Kress et al. (2003: 299) list this name for an entity from Myanmar, citing its distribution and common names within that country, and describing the plant simply as a 'Tree'.The name A. microcephala Graham first appeared in Wallich Num.List [Wallich] n. 5263 (1831[Wallich] n. 5263 ( -1832)).Names on this list are regarded being effectively published but are to be treated as nomina nuda unless a subsequent combination cites (or infers) a basionym, in which case they are considered to be validly published (Forman 1997).We consider the Kress et al. (2003)

Acacia obcordata Hemsl.
This name appears in Kress et al. (2003: 300) who say that it is "Reported from Myanmar"; the only other information provided is that the plant is described as a "Small tree".We have not been able to locate this name in any source available to us and it is therefore considered nomen nudum, but the taxon to which this name might apply is unknown.
Macfadyen (1837)cro cephala Graham as a nomen nudum.Besides, even if it were regarded as having validly published it would be a nom.illeg.because it would be a later homonym on account of A. micro cephalaMacfadyen (1837).The taxon to which Kress et al. applied the name A. microcephala is perhaps A. leucophloea var.