Danaea alba Keskiniva & Tuomisto, 2024

Keskiniva, Venni & Tuomisto, Hanna, 2024, Danaea (Marattiaceae) keeps diversifying, part 1: eighteen new species, Willdenowia 53 (3), pp. 173-228 : 175-177

1. Danaea alba Keskiniva & Tuomisto , sp. nov. ( D. subg. Danaea ) – Fig. 2 .

Holotype: Panama, Colón, Parque Nacional San Lorenzo . collected at PPina1, 09°08'N, 79°43'W, 181 m, 4 Sep 2008, Jones 1212 ( PMA! (72300); isotype: TUR! (mounted on 3 sheets, has separate rhizome)).

Diagnosis — Similar to Danaea grandifolia Underw. but differs in light yellow-green colour of laminae (vs dark blue-green); acuminate pinna apices (vs usually cuspidate); a node sometimes present on petiole (vs never); elliptic shape of juvenile pinnae (vs oblong); genetically differs in locations 562 (C vs T) of atpB reference sequence; 811 (C vs T) of rbcL reference sequence; 445 (T vs C), 912 (C vs G) of rpl32 reference sequence.

Description — Rhizomes creeping, dorsiventral, 5 cm in diam., 15 cm long, leaf bases in 3–5 rows. Sterile leaves 160–200 cm long; petioles 79–90 cm long, with 0–1 node, not winged; laminae 75–93 × 65–90 cm, obovate, imparipinnate, terminal pinnae shorter than second distal-most pinna-pair, 8–9 pinna-pairs, pinnae equidistant and rather uniform in size, medial pinnae 5.5–6.5 cm apart, concolorous, uniformly (very) light yellowish or greyish green, texture thick and leathery to intermediately thick, pinna margins slightly cartilaginous, rachises not winged; terminal pinnae 12–28 × 3.7–6.2 cm, long-elliptic to oblong (to lanceolate), bases acute to cuneate; largest lateral pinnae 33–37 × 5.2–5.5 cm, 5.6–7.9 times as long as wide without apex, widest at middle, parallel-sided or (rarely) slightly wider above middle, bases symmetrical (acute) or asymmetrical (acute distally, obtuse proximally), apices 1.2–3 cm long, acuminate, margins of apices entire; veins 12–16 per cm, mostly forked at costa. Fertile leaves not known. Juveniles with creeping rhizomes with leaf bases in two rows, pinnae uniform in size, terminal pinnae lanceolate, lateral pinnae long-elliptic, margins of apices entire, smallest pinnate juvenile seen 48 cm long (already with 3 pinna-pairs).

Distribution and habitat — Known from the lowland forests of Panama (Colón, Darién, and Panamá) up to 215 m. Fig. 3 .

Conservation status — We place Danaea alba in the Near Threatened (NT) category ( IUCN 2012). It has an Area of occupancy of 16 km 2, an Extent of occurrence of 1083 km 2, and is known from only four locations, which correspond to the Endangered (EN) category. The paucity of collections, despite the large collection effort in Panama, indicates that this species is rare. However, all known collection localities are inside protected areas (Barro Colorado Island, Parque Nacional Darién, Parque Nacional San Lorenzo, and Parque Nacional Soberanía in Panama), and there appears to be no imminent threat to all subpopulations.

Etymology — Alba is Latin for white, referring to the pale colour of the dried pinnae.

Remarks — Danaea alba is a large species with relatively few pinna-pairs. It is similar in size and shape to D. grandifolia , but is distinct genetically. It can most readily be separated from D. grandifolia by the pale, yellow-green colour of dried samples (vs dark blue-green), the acuminate pinna apices (vs usually cuspidate), the elliptic shape of juvenile pinnae (vs oblong), and nodes sometimes present on petioles (vs never). In addition, D. alba has been found only in the lowlands (up to 215 m) of Panama ( Fig. 3 ) whereas D. grandifolia grows at higher elevations (600–1600 m) and has a wider distribution along the Caribbean coast of Colombia and Venezuela as well as in Puerto Rico and Hispaniola.

Danaea alba belongs to the group of species that have traditionally been identified as D. nodosa (L.) Sm. It differs from D. nodosa in having rhizomes with leaf bases in 3–5 rows (vs in two rows) and generally fewer pinna-pairs (8–9 vs 8–16) that have entire apices (vs often serrate) and symmetrical bases (vs usually asymmetrical). In addition, the pinnae of D. alba are, on average, larger (33–37 × 5.2–5.5 cm vs 21–35 × 2.6–5.8 cm) and thicker (leathery to medium thickness vs medium thickness).

Considering other species with potentially overlapping geographical distributions, Danaea alba differs from D. leussinkiana Christenh. and D. panamensis in having larger pinnae (33–37 × 5.2–5.5 cm vs less than 28 × 4.9 cm) that dry yellow-green (vs blue-green). In addition, rhizomes of D. alba have leaf bases in 3–5 rows (vs two rows in D. panamensis ).

Danaea megaphylla A. Rojas has a variable pinna shape, but D. alba differs from it by having creeping rhizomes (vs ascending to erect), fewer pinna-pairs (8–9 vs 12–18) that dry yellow-green (vs grey or brown), and by sometimes having a node on the petiole (vs never).

Danaea alba differs from D. ampla (described below) in having rhizomes with leaf bases in 3–5 rows (vs in two rows) and larger pinnae (33–37 × 5.2–5.5 cm vs 14–26 × 3.1–4.9 cm) that are parallel-sided (vs often oblanceolate) and thicker in texture (vs relatively thin).

Danaea alba differs from D. erecta Tuomisto & R. C. Moran in having creeping rhizomes (vs erect), sometimes a node on the petiole (vs never), and generally fewer pinna-pairs (8–9 vs 7–17) that dry light yellowish green (vs rather dark green or brown). Danaea erecta also grows at higher elevations ((300–) 500–2000 m vs 50–215 m).

Danaea alba differs from D. latipinna Tuomisto & R. C. Moran in having longer (33–37 cm vs 17–30 cm) but narrower pinnae (5.6–7.9 vs 2.4–3.4 times as long as wide without apex), terminal pinnae always present (vs often replaced by a bud), rhizomes with 3–5 rows of leaf bases (vs two rows), acuminate pinna apices (vs usually cuspidate to caudate), and a lighter lamina colour.

See Danaea antioquiana (described below) for comparison with that species.

Additional specimens examined — PANAMA: DARIÉN: Ensenada del Guayabo, 18 km from SE Jaque, 50 m, 1983, Garwood 163 (BM!); PANAMÁ: Parque Nacional Soberanía, at P16, 09°08'N, 79°43'W, 182 m, 3 Apr 2008, Jones 994 (TUR!, US!); PN Soberanía, at P8, 09°08'N, 79°45'W, 215 m, 28 Jan 2008, Jones 686 (TUR!); Barro Colorado, 1931, Wilson 103 (BRIT!).

Figures

Fig. 2. Danaea alba: A: creeping rhizome seen from above; B: apex of sterile pinna; C: juvenile; D: sterile leaf; E: creeping rhizome seen from side. – A, B, D, E: Jones 1212 (TUR); C: Jones 994 (TUR). – Drawn by Venni Keskiniva.

Fig. 3. Distribution of types and paratypes of Danaea alba, D. ampla, D. antioquiana and D. panamensis.