The genus Capparis L. (Capparaceae) in Laos and Cambodia

Summary. A taxonomic revision of the genus Capparis in Laos and Cambodia was undertaken. Based on examination of historical and recent herbarium collections coupled with ﬁ eld investigations, 25 species and 7 intraspe-ci ﬁ c taxa, all belonging to sect. Monostichocalyx , were recognised in the study area. Among these, a new species, C. averyanovii , and a new subspecies, C. acutifolia subsp. thamphae , from central and northern Laos are described and illustrated. A key to the species is provided, along with descriptions, synonyms, distribution ranges, autecolo-gical and phenological data, and 31 lectotypes are selected. When available, vernacular names and traditional uses of the species are also given, based on information from herbarium labels or bibliography. The occurrence of various taxa known only from type material is underlined. Based on the available data, C. diffusa and C. rotundifolia , two species formerly recorded from Cambodia, are excluded from the ﬂ ora of the study area.


Introduction
The genus Capparis L. includes about 150 species (POWO 2022) of small trees, shrubs and climbers occurring in a wide range of habitats in the tropical and subtropical areas of the Old World, with outliers in central Asia and the Mediterranean Region (Souvannakhoummane et al. 2020). In the Indo-Pacific area 82 species of the genus, belonging to four sections, i.e. sect. Capparis, sect. Sodada (Forssk.) Endl., sect. Monostichocalyx Radlk. and sect. Busbeckea (Endl.) Benth. & Hook.f., were recorded by Jacobs (1965). Recent surveys in south eastern Asia and the western Pacific have allowed the description of several new species from Thailand, Vietnam, Laos, Indonesia, Malaysia, Philippines and New Caledonia (Srisanga & Chayamarit 2004;Thuong et al. 2013Thuong et al. , 2015Thuong et al. , 2018Thuong et al. , 2020Fici 2012Fici , 2016aFici , 2016bFici , 2017aFici , 2017bFici , 2021Fici et al. 2018Fici et al. , 2020Fici & Souvannakhoummane 2020;Souvannakhoummane et al. 2018Souvannakhoummane et al. , 2020Julius 2022). The Indochinese Peninsula, comprising Myanmar, Thailand, Laos, Cambodia and Vietnam, is a major centre of speciation of Capparis, which includes several endemic species here (Jacobs 1965;Fici 2016a), but the diversity of the genus, and the distribution of its representatives, remain poorly investigated in most of this area. In Laos and Cambodia, a discordant number of intrageneric taxa was recorded by different authors (Gagnepain 1908b;Jacobs 1965;Callaghan 2004;Newman et al. 2007b;Inthakoun & Delang 2008;Lee 2016;Cho et al. 2016). In addition various Capparis species occurring in this area are characterised by complex variability in both vegetative and reproductive characters (Fici 2016a). Based on the above considerations, the taxonomic treatment of the genus in the study area is still critical. Therefore, the present work aims to provide a revision of Capparis in Laos and Cambodia through studies of herbarium collections coupled with field investigations.
With regard to the study area, three subspecies of Capparis acutifolia, i.e. subsp. acutifolia, subsp. viminea M.Jacobs and subsp. sabiifolia (Hook.f. & Thomson) M.Jacobs, were recorded by Jacobs (1965) and Fici (2016a). Furthermore, a new subspecies, characterised by the reduced size of the flower and ovary, is here described from northern Laos.
Based on the terminology adopted by Jacobs (1965), in the present treatment the term innovation refers to the "very young twigs with leaves as well as the young inflorescences". The following key includes the subspecies recognised in the study area.
Key to the subspecies in the study area  Jacobs (1965) as a kind of depauperation, occasionally occurring in the species. In the examined material from Laos (Nanthavong 144) the flowers are solitary or 2 in supra-axillary rows, and the ovary is c. 1.7 -2 mm long. With regard to Indochina, Jacobs (1965) recorded only a few collections of this subspecies from Annam. Of these, Schmid 9 has 2 -5 flowers in supra-axillary rows in the upper part of twigs and solitary flowers at the axil of lower leaves, pedicels 2 -2.8 cm long, sepals 5 -6 × 3 -4 mm, petals 8 -9 × 3.5 -4 and ovary c. 1.8 mm long; in Chevalier 40389 the flowers are solitary or 2 -3 in rows, the pedicels are 2 -2.5 cm long, the sepals 5 -6 × 2.5 -3 mm, petals c. 8 -9 × 4 mm and ovary c. 1.7 mm long.
PHENOLOGY. Flowering in March -May (Jacobs 1965;Chayamarit 1991). Based on the available material, flowers in March in Laos. VERNACULAR NAME. Lao: Sai su (Gagnepain 1939). NOTES. The plant is described as a straggling shrub on the type of Capparis vientianensis (Kerr 20748). In some cases the branches are reported as lacking stipular thorns (Chung et al. 2004;; in the specimens from Laos straight thorns up to 4 mm long are present, but in Fici 1850 the thorns are developed only on the older branches, lacking on the fertile twigs. In the latter specimen the sepals are tomentose inside, as reported by Chayamarit (1991) and Chung et al. (2004), and the petals are densely tomentose on both surfaces. Ficus marchandii H.Lév. (Léveillé 1913: 533). Type: [China] Kweichow, Esquirol s.n. (lectotype A 00039182 digital image!, selected by Jacobs (1965: 431)). Capparis viminea var. ferruginea B.S. Sun (1964: 112).

RECOGNITION.
Capparis averyanovii is related to C. assamica, differing in several characters, such as the innovations glabrous vs sparsely pubescent, leaf blades narrowly lanceolate or linear, 9.4 -12.5 times as long as wide vs 2.4 -3.5 times, nerves c. 11 -12 pairs vs 8 -10, inflorescence 9 -10.9 cm long vs 11 -20 (-28) cm, filaments c. ETYMOLOGY. The species is named after Leonid V. Averyanov, renowned botanist and expert on the Indochinese flora, collector of the type specimen. NOTES. Capparis averyanovii was recorded by the collectors as a small vine, while the related C. assamica is a shrub (Chayamarit 1991;). The new species shows also affinities with C. lanceolatifolia, a species recently described from the same province of Laos, characterised by similar, narrowly lanceolate leaf blades, but more than 1.8 cm wide, and by shorter sepals (2 -3 mm long), filaments (2 -3.5 mm long) and gynophore (3 -4 mm long).  Chun (1927: 21).
DISTRIBUTION. India (Andaman Islands), Myanmar, China (Guangdong, Guangxi, Yunnan, Hainan), Taiwan, Vietnam, Laos, Cambodia, Thailand, Malaysia, Indonesia, Philippines (Jacobs 1965;. NOTES. Capparis micracantha is a wide ranging, polymorphic species known from southern Asia, Indone-sia, the Philippines and Taiwan. Jacobs (1965) stated that in the past several taxa were described, based on forms representing extremes of the variation of this species. The same author split C. micracantha into two subspecies, i.e. subsp. micracantha, occurring in the study area and characterised by the sepals mostly obtuse, stamens fewer than 60 (-75) and fruit globose to ellipsoid, and subsp. korthalsiana (Miq.) M.Jacobs from Malaysia, Indonesia and Singapore, distinguished by the sepals acute to acuminate, stamens in higher number (60 -100) and fruit elongate. Furthermore, subsp. micracantha was split by Jacobs (1965) into two varieties, the widely distributed var. micracantha and var. henryi (Matsum.) M.Jacobs, endemic to Taiwan. Recently a new variety of subsp. microcarpa, var. microcarpa, characterised by short pedicels, sepals and ovary and small fruit, was described from central Laos (Fici 2016a).
DISTRIBUTION. Thailand, Cambodia, Vietnam. Gagnepain (1908a, 1908b reported the type locality of the species in Laos, whereas Jacobs (1965) (Chayamarit 1991). In Cambodia flowering material has been collected in February (Schmid s.n.), fruiting material in March (Pierre 790) and June (Poilane 17436). NOTES. Following Jacobs' (1965) treatment, Capparis thorelii belongs to the Subumbellates-Group. It is related to C. sepiaria, differing in the leaves which are glabrescent beneath and in the larger fruit on a thickened stipe. Furthermore, the ovary in C. thorelii is 1.1 -1.5 mm long, with a pronounced beak, while in C. sepiaria it is 1.5 -2 mm long and shortly beaked.  DISTRIBUTION. Myanmar, Malaysia, Laos, Vietnam, Indonesia (Sumatra). Recorded by Jacobs (1965) in peninsular Thailand, but the occurrence in this country was not confirmed by Chayamarit (1991 Jacobs (1965) underlined that Capparis trinervia, included in the Trinervia-Group, is characterised by great polymorphism. It is characterised by up to 10 (-15) flowers conferted at the top of twigs or on lateral subumbels, pedicels pubescent up to 3.3 (-5) cm long, sepals outside pubescent, gynophore puberulous at the base, and globose fruit up to 5 cm in diam. In the specimens from Laos, leaves have three pairs of nerves, of these the first one is thin and departing from the leaf base, while the upper two pairs are thicker; however the pattern and number of nerves is very variable along the wide distribution range of the species.
the occurrence of Capparis diffusa in Cambodia cannot be confirmed. However, the distribution of this species in the area should be more carefully investigated.
A species recorded from India, Sri Lanka, Myanmar and doubtfully from Cambodia by Jacobs (1965). The only collection with a label reporting the latter country is Pierre s.n. (P 05454917), collected in 1870, but Jacobs (1965) suggested that "On his way thither Pierre collected in southern India; his specimen might actually be from there". Based on the whole distribution pattern and lacking other collections from Indochina, the occurrence of Capparis rotundifolia in Cambodia is highly improbable. Recently the species, under the synonyms C. longispina Hook.f. & Thomson and C. orbiculata Wall. ex Hook.f. & Thomson, was confirmed in Myanmar by Kress et al. (2003), while Maurya et al. (2020) reported it only from India and Sri Lanka. supporting taxonomic research on the flora of southeastern Asia.

Funding
Open access funding provided by Università degli Studi di Palermo within the CRUI-CARE Agreement.

Declarations
Conflicts of interests. No potential conflict of interest was reported by the author.
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