The genus Callitriche (Plantaginaceae: Callitricheae) in South America Author Lansdown, Richard V. 0000-0003-0984-4552 Ardeola Environmental Services, 45 The Bridle, Stroud, Gloucestershire, GL 5 4 SQ, United Kingdom & Honorary Research Associate, Royal Botanic Gardens, Kew, Richmond, Surrey, TW 9 3 AE, United Kingdom & r. lansdown @ kew. org; https: // orcid. org / 0000 - 0003 - 0984 - 4552 r.lansdown@kew.org Author Hassemer, Gustavo 0000-0003-4365-6934 Câmpus de Três Lagoas, Universidade Federal do Mato Grosso do Sul, CEP 79613 - 000, Três Lagoas, MS, Brazil & g. hassemer @ ufms. br; https: // orcid. org / 0000 - 0003 - 4365 - 6934 g.hassemer@ufms.br text Phytotaxa 2021 2021-05-19 501 1 85 118 http://dx.doi.org/10.11646/phytotaxa.501.1.3 journal article 10.11646/phytotaxa.501.1.3 1179-3163 5424744 1. Callitriche albomarginata Fassett (1951: 171–172 , t. 1173[11]) Type: — CHILE . SANTIAGO. Cordillera de Santiago , 2700 m , March 1899 , Reiche s.n. ( holotype GH barcode 00002215!) . Description: —Stem and leaf scales present. Leaf bases connate. Lingulate leaves unknown, expanded submerged or floating leaves spathulate, elliptic, 2.6–2.9 × 1.6–2.1 mm , petiole 2.2–3.8 mm , venation fairly simple, 3-veined with numerous subsidiary veins looping from secondary veins or anastomosing, the apical leaves forming a floating rosette, leaves of terrestrial plants unknown. 1 ♂ and 1– 2 ♀♀ flowers in each aXil. Bracts rapidlY caducous, minute, 0.1–0.2 mm long. StYle erect ≤ 1 mm . Filament ≤ 2.5 mm , anther 0.4 mm diameter, pollen Yellow. Fruit not strumose, subsessile or on pedicel ≤ 0.5 mm , longer than wide, blackish when mature, 1.0–1.1 × 1.1–1.3 mm , narrowlY winged throughout, wing whitish contrasting with colour of fruit. TABLE 1. The number of specimens of each taxon seen from each south American country. A—Argentina, BO—Bolivia, BR—Brazil, C—Chile, CO—Colombia, E—Ecuador, PA—Paraguay, PE—Peru, UK—Falkland Islands and South Georgia, U—Uruguay, V—Venezuela.

Species / subspecies	A	BO	BR	C	CO	E	PA	PE	UK	U	V	Total
C. albomarginata	1	1
C. antarctica	3	2	10	15
C. berteroana	10	10
C. ciliata	1	1	2	4
C. concinna	6	2	2	10
C. dacryoidea	1	1
C. deflexa	12	6	1	7	26
C. ecarinata	4	1	1	6
C. hegelmaieriana	2	2
C. heterophylla	6	1	3	2	1	2	1	16
C. heteropoda	7	2	9
C. lechleri	12	1	19	1	3	2	38
C. mandonis	6	3	5	14
C. nubigena	5	5
C. oblongicarpa	4	1	1	6
C. praetermissa	1	1	2
C. quindiensis	1	1
C. rimosa	1	19	1	1	1	1	24
C. schotsmaniana	2	2
C. stagnalis	1	1	2
C. terrestris	22	3	12	1	3	4	2	2	49
C. turfosa	30	3	5	6	4	4	2	1	55
Total	97	24	42	46	20	13	6	17	11	16	6	298

Illustrations: —plate 1173(11) in Fassett (1951) ; Figure 1 (a). Distribution: — Callitriche albomarginata is known only from the type specimen, collected from the Cordillera de Santiago in Chile in 1899. The type was collected at an altitude of 2700 m . See map on page 173 in Fassett (1951) . Notes: —There have been published reports of Callitriche albomarginata ( e.g. de la Barra 2003 ), however there is no evidence that the identifications have been based on comparison with the type . It seems better therefore to dismiss these records. Callitriche albomarginata can be distinguished from all other Callitriche species in the region by the minute bracts and the large fruit which are typically> 1 mm diameter and winged throughout. Of all South American Callitriche species , C. albomarginata most closely resembles C. nubigena , from which it differs in its apparent lack of lingulate leaves, the bract size, style length, fruit size and the wing being wider at the apex. Conservation status: —Information on this species is inadequate to derive an informed assessment and it is therefore classed as Data Deficient (DD).