Callitriche praetermissa Lansdown & Hassemer, 2021

Lansdown, Richard V. & Hassemer, Gustavo, 2021, The genus Callitriche (Plantaginaceae: Callitricheae) in South America, Phytotaxa 501 (1), pp. 85-118 : 107

16. Callitriche praetermissa Lansdown & Hassemer , sp. nov.

Type: — CHILE. MAGALLANES: In a tarn, near Hotel Rio Rubens (about 50 km SE of Natales), 18 January 1941, R. Santesson 1637 (holotype NY!) .

Diagnosis: — Callitriche praetermissa can be distinguished from all other Callitriche species by the combination of unwinged fruit ≥ 1 mm in diameter and widest in the middle, persistent bracts, long filament (≤ 4 mm long) and ♂ and ♀ flowers in each aXil or in one, opposed bY a solitarY flower.

Description: —Stem and leaf scales present. Leaf bases connate. Lingulate leaves parallel-sided, 9.6–13.2 × 0.5– 1.1 mm, expanded submerged or floating leaves narrowly elliptic, 5.6–8.0 × 1.7–2.4 mm, petiole 1.8–4.3 mm long, venation usually simple but occasionally short branches arise outside the secondary veins and extend either toward or awaY from the apeX, apical leaves forming a floating rosette, leaves of terrestrial plants unknown. TYpicallY a ♀ and ♂ flower in one aXil, opposed bY a single ♀ flower. Bracts persistent, 0.5–1.7 mm long. StYles caducous, ≤ 1.0 mm long. Filaments ≤ 4.1 mm; anthers 0.2–0.3 mm diameter; pollen Yellow. Fruit not strumose, subsessile, ± isodiametric, brown when mature, 1.0–1.1 × 1.0– 1.2 mm, unwinged.

Illustrations: — Figure 5 (e).

Distribution: — Callitriche praetermissa is known only from the type specimen which was collected from a tarn near Magallanes, Chile in 1941.

Etymology: —The specific epithet means “overlooked” or “neglected” because this is not a striking species and has been overlooked by other botanists.

Notes: — Callitriche praetermissa is known only from the type gathering, it is not a particularly striking species and in a genus which is extremely under-collected it is not surprising that it has been overlooked. There is a need to re-visit the type locality to establish whether it still occurs and to survey potentially suitable habitat in the region to attempt to find other populations.

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

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.