Taxonomic list of the vascular flora of the islands of San Andres and Old Providence , Colombia

We present an updated list of 532 vascular plant species distributed in 375 genera and 110 families on the islands of San Andres and Old Providence, Colombia, based on a compilation of published literature and some additional observations. The following nine plant species are new plant records for the islands: Cycas circinalis L. (Cycadaceae), Clerodendrum trichotonum Wall., Mentha viridis (L.) L., Ocimum americanum L. var. americanum, O. basilicum var. purpurascens Benth., O. campechianum Mill. (Lamiaceae), Pandanus sp. (Pandanaceae), Duranta repens L. and Lantana involucrata L. (Verbenaceae).


INTRODUCTION
The Archipelago of San Andres, Old Providence and Santa Catalina lies in the Colombian Caribbean Sea between 12° and 16° North and between 78° and 82° West (Lowy 2000).San Andres Island is characterized by its elongated shape, having a length of 13 km and an average width of 2.5 km.It covers a total area of 27 km 2 and its highest point is 87 m high (Vargas 2004).The island of Old Providence is of volcanic origin, with a maximum altitude of 350 m above sea level (a.s.l.), and its vegetation composed of trees and shrubs is classified as tropical dry forest (Tobar and Gavio 2011).
The vegetation of the islands is classified as transitional forest, finding elements of both the dry forest and tropical rain forest (Gonzalez et al. 1992;Lowy 2000).The natural vegetation has been completely transformed on San Andres and on the island of Old Providence it is relatively well preserved (partially altered) in the higher parts of the island (Marquez 2006;Tobar and Gavio 2011).It has been estimated that 77% of the flora in the Archipelago is endemic and the remaining 23% are introduced species (Lowy 2000).In another more recent study, Tobar et al. (2013) indicated that 70% of the flora of the Archipelago is endemic and that 30% is introduced.According to Diaz and Lowy (1992) and Gonzalez et al. (1995), the flora of the Archipelago has not been studied extensively, and between these two studies a total of 374 species of vascular plants (326 dicots, 40 monocots and seven pteridophytes) were recorded.Subsequently, Lowy (2000) compiled all the botanical information available on the islands, including written contributions by Toro (1929), Proctor (1950), Barriga (1969), Chiriví (1988), Diaz and Lowy (1992), Gonzalez et al. (1995) and herbarium collections, recording a total of 409 vascular plant species for the Archipelago (102 families of Pteridophyta and Espermatophyta).Later, Ruiz and Fandiño (2007) recorded 67 plant species for Old Providence, of which 13 were new plant-species records for the Archipelago; and Tobar and Gavio (2011) recorded the invasive fern Pteridium caudatum (L.) Maxon (Dennstaedtiaceae) on the same island, bringing the number of plant species recorded in the Archipelago to 423.Kondo et al. (2012) presented a list of 82 host plants for the invasive Colombian fluted scale insect, Crypticerya multicicatrices Kondo & Unruh (Hemiptera: Monophlebidae) on San Andres island and listed other 13 plant species which are not affected by the insect pest, for a total of 95 plant species.The list given by Kondo et al. (2012) included 50 species of plants which turned out to be new plant records for the Archipelago (i.e., not included in the list by Lowy [2000]), elevating the number of plant species in the Archipelago to 473 species.Recently, Tobar et al. (2013) added 58 new species records to the islands, including 8 plant species already cited by Kondo et al. (2012), increasing the vascular flora of the Archipelago to 523 species.In the present study we add nine new plant species records, i.e., two species recorded from

RESULTS
Pandanus sp.(Pandanaceae) (Figure 1E) represents the first record of this family in the Archipelago, being observed and photographed by TK at Haynes Cay, 12°33′02.8″N, 081°41′20.5″W, 10 m a.s.l., on 17 January 2012.Cycas circinalis L. (Cycadaceae) is herein also reported as a new plant record for the islands.Some of the voucher specimens of C. revoluta Thumb.deposited at HJBSAI-UN were newly identified as C. circinalis in the present study.Additionally, seven new species records for the Archipelago which were listed in the first author's unpublished undergraduate thesis are also herein included, i.e., Duranta repens L. (Figure 1B), Lantana involucrata L. (Figure 1A), Mentha viridis (L.) L., Ocimum americanum L. var.americanum, O. basilicum var.purpurascens Benth.(Figure 1D) and O. campechianum Mill.(Figure 1C) (Tobar et al. 2008).Here we provide an updated list of 532 plant species distributed in 375 genera and 110 families of vascular plants on the islands of San Andres and Old Providence, based mainly on a compilation of published literature and some additional observations (Table 1).

DISCUSSION
The flora of the Archipelago has a greater affinity with the flora of Central and South America, compared with the flora of the Antilles.This is due to the proximity of the islands to Central America, which favors a unique flora that has resulted from different dispersal mechanisms.Lowy (2000) presented another hypothesis that is based on transoceanic dispersal opportunities between Central America and the Greater Antilles.
In the present study we have compiled a list of the vascular plants of San Andres and Old Province based on new observations and available literature.As can be observed by the high number of species reported in recent years, it can be said that this is a preliminary list of the actual number of plant species in the Archipelago of San Andres, Old Providence and Santa Catalina.Recently, Silva-Gómez et al. (2013)  new observations and seven plant species reported in the unpublished Bachelors' thesis by the first author (Tobar et al. 2008).The thesis by Tobar et al. (2008) listed 11 plant species for the island of San Andres, of which seven were new species records for the region, which have not been hitherto officially published, raising the number of species on the islands of San Andres and Old Providence to a total of 532 species.

MATERIALS AND METHODS
Herein we have compiled a list of vascular plants based on available literature and some additional observations (see Table 1).Scientific names were verified using the plant nomenclature database: "The Missouri Botanical Garden's VAST (vascular Tropics) (Missouri Botanical Garden: w3TROPICOS 2013)", and for some plant names, the USDA Plant database was also used.Plant names which could not be verified by w3TROPICOS nor the USDA Plant database were marked with an asterisk (*) before the plant name, e.g., *Chomelia speciosa L. Listing all synonyms was out of the scope of this work; however, in order to avoid double counts in the future we listed the synonyms reported in the cited literature in squared brackets just after the valid name.For example: Dicliptera assurgens (L.) Juss is reported by Díaz and Lowy (1992) as Dicliptera vahliana, but the latter is treated as a synonym in w3TROPICOS, thus in the list below, D. vahliana is listed within square brackets.In Table 1, new species records for the region are indicated by two asterisks (**) before the plant name, e.g., **Cycas circinalis L. Abbreviations for repositories (Herbaria) follow Thiers' (continuously updated) Index Herbariorum (see below).

Abbreviations in the table
Repositories.COL:   1 because there were neither voucher specimens nor photographic records to confirm their plant identifications.
In order to better understand the flora of the Archipelago, it is important to provide additional information, e.g., their usage, economic importance, and origin.Introduced plant species are becoming abundant in urban areas of San Andres, especially ornamental plants (Tobar et al. 2013), which often are introduced with associated insect pests, as has been the case of the Colombian fluted scale insect, Crypticerya multicicatrices (Kondo et al. 2012).During recent visits to the island of San Andres, TK noticed that the invasive weed Flemingia strobilifera (Figure 1F), a plant of Asian origin (Tropicos 2013) is now found commonly throughout the island.

ACKNOWLEDGMENTS
The first author thanks the unconditional support of the Environmental Engineer Johnny Walker Cardenas; to biologist Luis Alberto Guerra, for his support and contributions to her thesis; to Dr. Brigitte Gavius, for her guidance during her stay at the National University of Colombia, Carib campus and for being an example to follow; to Professor Petter Ceron Lowy and Dr. José Luis Fernández Alonso, who unconditionally supported the first author's thesis entitled: "Contribution to the knowledge of the Labiatae and Verbenaceae families with emphasis on ethnobotany on the island of San Andrés, Colombia", to qualify for the title of Biologist, at the National University of Colombia, Carib campus, making very important contributions.The second author thanks the Colombian Ministry of Agriculture and Rural Development (MADR) for its financial support, under Corpoica-MADR agreement No. 1810, project title: "Búsqueda de enemigos naturales de Crypticerya multicicatrices y ensayos con extractos vegetales".The authors thank anonymous reviewers for reviewing the manuscript.

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Table 1 .
Silva-Gómez et al. (2013)d Kondo | Flora of San Andres and Old Providence, Colombia oleracea (Amaranthaceae), Swietenia macrophylla (Meliaceae) and Syzygium jambos (Myrtaceae).Although it is likely that the plant species reported bySilva-Gómez et al. (2013)may occur on the islands, they were not included in Table