Arenaria mattfeldii Baehni, Publ. Field Mus. Nat. Hist., Bot. Ser. 13(2/2): 601. 1937.

Montesinos-Tubee, Daniel B. & Iamonico, Duilio, 2023, Neotypification for five names linked to Arenaria (Caryophyllaceae) for the endemic flora of Peru and Bolivia, PhytoKeys 230, pp. 131-144 : 131

Arenaria mattfeldii Baehni, Publ. Field Mus. Nat. Hist., Bot. Ser. 13(2/2): 601. 1937.

Neotype

(designated here). Peru. La Libertad: Llautabamba, Huamachuco, 4650 m, 8 May 1954, J. Infantes 4672 (B100747343!, Fig. 2 ).

Macbride (1937: 601) validly published Arenaria mattfeldii providing a detailed diagnosis accompanied by the following note: “Junín: Yauli, above the Hacienda Arapa, near the Lima-Oroya railroad, Weberbauer 353 (type, in Herb. Deless.)". "Herb. Deless." means "Herbarium Delessert". According to HUH-Index of Botanists (2013a), the surname “Delessert” refers to, at least, three different people, i.e. Adolphe Delessert (collector in India, Indonesia, Malaysia, Reunion), Henri Delessert (collector in Cuba), and Jules Paul Benjamin Delessert (collector in Brazil). Unfortunately, Macbride (1936: 9-81), in the Introduction of his Flora of Peru, did not mention “Delessert” and we did not find any other reference to an "Herb. Deless." throughout the various volumes of the flora. However, based on the collector reported by Baehni in Macbride (1937: 601), i.e., Weberbauer, we tried to search original material at B, where Weberbauer’s collection is preserved ( HUH-Index of Botanists 2013b). Unfortunately, no specimen could be traced (the section holding these collections at herbarium B was destroyed during the II World War). No other specimen useful for the purpose of lectotypification was found. We traced only a photograph (no. 29871) of the original Weberbauer’s collection no. 353 at F and MO (Fig. 1 ). However, this photograph, which was made after 1937, cannot be considered as part of the original material for A. mattfeldii under the Art. 9.4a of ICN; hence a neotypification is required under the Art. 9.8 of the ICN. We here designate as a neotype, a specimen collected in Peru and preserved at B (B100747308).

Observations.

The species is considered narrowly endemic to Junín and designated as Critically Endangered by Cano and Sánchez (2006).

Description.

Perennial herb, densely caespitose, matt-forming, 3-5 cm height, 10 cm wide; leaves 1.5-2.0 mm long, closely imbricate, shortly appressed, thick, lamina with deltate to broadly ovate, apex obtuse or rarely acute, base truncate; margins shortly revolute and ciliate, trichomes simple, 0.10-0.15 mm long and irregularly shaped, rarely straight, leaf lamina surface glabrous both on the upperside and underside, and without a visible midrib; flowers apical, pedicels <1 mm long, sepals 2 mm long, ovate-deltate, apex slightly curved downwards; petals reduced, ovate, translucid, ½ as long as sepals; stamens 10, ovary 0.75-1.00 mm long, glabrous, styles two; seeds about 8, with smooth surface.

Specimens examined.

Peru. Junín: La Oroya, Morococha, Hacienda Pucara , 4700 m., 23 May 1974, P. Gutte 2353b (LPZ!) .

Figures

Figure 1. MO sheet of the type photograph of Arenaria mattfeldii [Weberbauer 353].

Figure 2. Neotype of Arenaria mattfeldii Baehni (J. Infantes 4672, B 100747308).