Callitriche schotsmaniana Lansdown & Hassemer, 2021

Lansdown, Richard V. & Hassemer, Gustavo, 2021, The genus Callitriche (Plantaginaceae: Callitricheae) in South America, Phytotaxa 501 (1), pp. 85-118 : 109

19. Callitriche schotsmaniana Lansdown & Hassemer , sp. nov.

Type: — COLOMBIA. CUNDINAMARCA: Chisaca Páramo , southwest of Bogotá, 16 January 1966, J.W. Walker 273 (holotype GH!) .

Diagnosis: — Callitriche schotsmaniana can be distinguished from all other Callitriche species by the isodiametric fruit,> 1 mm diameter but unwinged.

Description: —Stem and leaf scales present. Leaf bases connate. Linear leaves ± parallel-sided, apex deeply notched to the extent that the notch is almost circular, 5.6–12.0 × 0.3–0.4 mm, expanded floating or submerged leaves unknown, apical leaves forming a floating rosette, leaves of terrestrial plants unknown. Flowers solitary. Bracts large, rapidlY caducous, 1.2 mm long. StYles erect, persistent, ≤ 4 mm long. Filaments erect, ≤ 0.2 mm long before dehiscence, <1.5 mm long after dehiscence; anthers 0.30–0.45 mm diameter; pollen Yellow. Fruit not strumose, shortlY pedicellate, isodiametric or wider than high, rich rufous-brown and shiny when mature, 1.0–1.3 × 1.0– 1.3 mm, unwinged.

Illustrations: — Figure 5 (h).

Distribution: — Callitriche schotsmaniana is known only from two specimens, both from Cundinamarca Province of Colombia and both collected on the same day.

Etymology: —The specific epithet commemorates the Dutch botanist Henriette Dorothea Schotsman (1921– 2004), who greatly contributed to taxonomic knowledge of Callitriche .

Notes: — Callitriche schotsmaniana is known only from two gatherings from the same area and it is likely that these do not include representation of the full range of variation. The fruit appear to be unique within the genus in having a thicker central area surrounded by a thinner zone which would equate to the wing in most species, but there is no structural differentiation within this thinner area. This could be affected by the preservation process and more material is needed to enable better description of the fruit.There is a need for more survey and data collection from the area in which the collections were made.

Conservation status: —Available information is inadequate to derive an informed assessment of the conservation status of C. schotsmaniana and it is therefore classed as Data Deficient (DD).

Additional material studied (paratypes): — COLOMBIA. CUNDINAMARCA: Chisaca Páramo , southwest of Bogotá, 16 January 1966, J.W. Walker 274 (GH, NY)

Figures

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.