Callitriche rimosa Fassett (1951: 211

Lansdown, Richard V. & Hassemer, Gustavo, 2021, The genus Callitriche (Plantaginaceae: Callitricheae) in South America, Phytotaxa 501 (1), pp. 85-118 : 108

18. Callitriche rimosa Fassett (1951: 211 , t. 1175[22])

Type: — URUGUAY. MONTEVIDEO: Santiago Vasquez , November 1924, W.G.F. Herter 695a (holotype GH barcode 00048937!; isotypes CM!, MO-260423!, NY barcode 00248747!, UC!, WIS!) .

Description: —Stem and leaf hairs present. Leaf bases connate. Lingulate leaves unknown, expanded floating or submerged leaves elliptic or rarely narrowly oblong, 4.1–10.1 × 2.9–7.4 mm, petiole 1.2–3.6 mm, venation complex with many parallel veins both within and outside secondary veins, as well as loops and arcs, the apical leaves forming a floating rosette, leaves of terrestrial plants unknown. TYpicallY 1 ♀ and 1 ♂ flower in each aXil. Bracts oval or subfalcate 0.6–1.0 mm. StYles erect, ≤ 1.1 mm long. Filament erect ≤ 1.3 mm long, generallY curved at dehiscence, anther 0.1 mm wide, pollen yellow. Fruit strongly or weakly strumose, subsessile, ± as wide as high, brown contrasting with white wing when mature, 0.7–1.4 × 0.7–1.3 mm, winged throughout, extending strongly into commissurial groove.

Illustrations: —plate 1175(22) in Fassett (1951); Figure 2 in Bacigalupo (1979b); Figure 5 (g).

Distribution: — Callitriche rimosa occurs in north-east Argentina (Buenos Aires, Corrientes, Entre Ríos), southern Brazil (Parana, Rio Grande do Sul, Santa Caterina) and Uruguay (Montevideo, Rocha) with single gatherings from Chile (Biobío), Paraguay (Misiones) and Peru (Puno). Known altitudinal range: 600–3900 m. See map on page 210 in Fassett (1951).

Notes: — Fassett (1951), Bacigalupo (1975) and Hassemer & O’Leary (2018) all employed a concept of Callitriche rimosa which included C. mandonis and elements of C. concinna . While there is some similarity, as considered here C. rimosa includes plants with fruit which are pale grey-brown when mature, typically 0.7–1.2 mm wide, often strongly strumose and winged throughout, with the wing extending well into the commissurial groove. Callitriche mandonis includes plants with fruit which are winged only at the apex and top of the sides, while C. concinna includes plants which have small fruit which are broadly winged throughout but not into the commissurial groove and which are blackish-brown when mature. When considered in this way, C. rimosa is not particularly variable except in the degree to which the fruit are strumose, which may be influenced by preservation. The main diagnostic character is the extent to which the wing extends into the commissurial groove at the base of the mericarps.

The illustrations in Figure 2 in Bacigalupo (1979b) show an aborted anther on a filament which arises from the pedicel. This is an extremely unusual morphology within the genus, otherwise only known from four species: C. capricorni Mason (1959: 307 , f. 3), C. cycloptera , C. muelleri and C. sonderi Hegelmaier (1867: 18–19) occurring in Oceania ( Schotsman 1985b) and C. occidentalis Hegelmaier (1864: 57 , t. 4[5]) which is known only from Cuba (R.V. Lansdown, unpublished data). This character needs to be confirmed through study of fresh material.

Conservation status: — Callitriche rimosa appears to be widespread and at least locally abundant, it is therefore classed as Least Concern (LC).

Additional material studied: — ARGENTINA. BUENOS AIRES: Moist earth, subtropical rain forest, Punta Lara, La Plata, 6 November 1946, B. Sparre 35 (K); CORRIENTES: Puddles of rainwater on clayey soil, “La Yela”, Empedrado Dept., 7 October 1980, T.M. Pederson 12936 (BR barcode BR0000000938263, C, F, NY); top leaves floating, temporary pool a few inches deep, on clayey soil, Estancia “Santa María”, Mburucuyá Department, 5 August 1961, T.M. Pedersen 6055 (BR barcode BR0000024932790, C, GH, K, P barcode P04214917); en charcos del bord de la selva, selva con pindo, 35 km SE de San Luis del Palmar, ruta 5, San Luis del Palmar Department, 2 November 1975, C.L. Cristóbal 1408 (G); en arroyo, sumergida, Costa del Rio Uruguay, Garruchos, Estancia San Juan Bautista, 20 September 1974, A. Krapovickas et al. 25867 (G); ENTRE RÍOS: Selve marginal, Paso Yunque, La Paz Department, Entre Ríos, 18 November 1988, N.M. Bacigalupo et al. 660 (NY); acuática con hojas flotantes y terrestre en el fango, San Jaime de la Frontera, Arroyo Tunas, 27 November 1976, N.S. Troncoso et al. 1459 (SI), mixed collection two packets of C. terrestris and two mounted specimens of C. rimosa ; camino al Balneario El Nandubaysal, 25 th September 1977, N. Troncoso et al. 2128 (SI-095397). BRAZIL. September 1998, J. Czermak & E.M. Reineck 472 (G barcode G00414769); PARANÁ: Interior do capao, brejo, Sete Butieiros (mun. Palmas), 20 November 1972, G.G. Hatschbach 30773 (G barcode G00414839, US-2688655 barcode 00609901); nas águas tranqüilas de córrego, Rincão, São José dos Pinhaes, 22 January 1950, G.G. Hatschbach 1764 (US-1998165 barcode 00609902); 2 January 1904, P.K.H. Dusén 14677 (US-2203301 barcode 00609897); aquática, em águas de valo, Horto Municipal do Guabirotuba (mun. Curitiba) 26 November 1991, J. Cordeiro & E. Barboza 794 (BR barcode BR0000024932820, C); cubre la superficie de agua [illegible], Estancia La Potala, proxima a Estancia Libertad, 26 October 1950, E.G. Nicora 5499 (SI); RIO GRANDE DO SUL: Barreto, Viana prope San Leopoldo, 24 October 1949, B. Rambo 44063 (BR barcode BR0000024932943, F, P barcode P04214960); São Leopoldo, August 1941, E. Leite 2804 (GH); prope Farroupilha, 13 July 1949, B. Rambo 42537 (P barcode P04214959); in graben au die Avenita Encuestro, Porto Alegro, September 1898, E.M. Reineck & J.Czermak 472 (P barcode P04214857); SANTA CATARINA: Slough, Trinta-tres, 33 km west of Caçador, Caçador Municipality, 900–1000 m, 23 December 1956, L.B. Smith & R. Reitz 9102 (US-2282293 barcode 00609891); between Fazenda Santo Antonio and the falls of the Rio Canoas, Campo dos Padres, Bom Retiro Municipality, 1300–1400 m, 22 November 1956, L.B. Smith & R.M. Klein 7830 (US-2282250 barcode 00609889); 22 June 1885, Schwacke 14678 (US-2203302 barcode 00609898, US-1199738 barcode 00609895); small stream in sun, Mun. Chapecó Forest, Seminario Diocesiano, west of Chapecó, ca. 27 º 06’ S, 52 º 37’ W, 350–450 m, 9 November 1964, L.B. Smith & R.M. Klein 13090 (F, NY P barcode P04214838, US-2743511 barcode 00609931); brook, Três Pedrinhas, 12 km southwest of Săo JoaQuim, Santa Catarina, ca. 28º 22’ S, 49º 57’ W, 1200–1300 m, L.B. Smith & R. Reitz 14335 (NY, P barcode P04214835, US-2743509 barcode 00609933); brook, Mun. Aguas de Chapecó, Lajeado Bonito, ca. 27 º 13’ S, 52 º 54’ W, 15 October 1964, L.B. Smith & R. Reitz 12548 (F-V0308533F, GH, NY, P barcode P04214839, US-2743510 barcode 00609932); falls of Rio Canoas, Campo dis Padres, Mun. Bom Retiro, 1300–1400 n, 22 November 1956, L.B. Smith & R. Klein 7854 (P barcode P04214910); small stream, Linhe Bonita, Ipumerim Municipality, 26º 58’ S, 52º 11’ W, 600 m, 24 October 1964, L.B. Smith & R. Reitz 12911 (P barcode P04214837, US-2743531 barcode 00609930); in aquis, Sao Benito, 22 June 1885, Schwaite s.n. (P barcode P04214849); [illegible] Blumenau, 19 October 1886, H. Schenck 715 (C). CHILE. BIOBÍO: Concepción, 27 November 1944, E. Barros 5558 (US-2168162 barcode 00609892). PARAGUAY. MISIONES: Temporary puddles a few ins deep, soil clay, Estancia “La Soledad”, Isla Carpincho, Santiago, 23 September 1962, T.M. Pedersen 6536 (C). PERU. PUNO: Ad oram lacus Titicaca, prope civitatem Huancane, 3900 m, 25 October 1976, L. Bernardi et al. 16886 (G barcode G00414945). URUGUAY. MONTEVIDEO: Terrain humide, Punta Brava, Fruchard s.n. (P barcode P04214936); sous l’eau, Cuarein, 24 September 1902, M.B. Berro 2850 (C); ROCHA: Castillos, Rocha Department, 31 November 1946, W.G. Herter 941 (F).

Figures

FIGURE 2. Lectotype of Callitriche antarctica (J.D. Hooker s.n., MEL barcode MEL2409648). Copyright: Royal Botanic Gardens Victoria.

FIGURE 5. Fruits of South American Callitriche: a—C. lechleri, b—C. mandonis, c—C. nubigena, d—C. oblongicarpa, e—C. praetermissa, f—C. quindiensis, g—C. rimosa, h—C. schotsmaniana, i—C. stagnalis, j—C. terrestris, k—C. turfosa.