Danaea kessleri Keskiniva & Tuomisto, 2024

Keskiniva, Venni & Tuomisto, Hanna, 2024, Danaea (Marattiaceae) keeps diversifying, part 1: eighteen new species, Willdenowia 53 (3), pp. 173-228 : 201-202

9. Danaea kessleri Keskiniva & Tuomisto , sp. nov. (D. subg. Danaea ) – Fig. 19, 20.

Holotype: Ecuador, Napo, 7 km SW of Tena, 2 km N of Río Napo, ecotourism area managed by Aventura Tours , 01°03'S, 77°51'W, 690–800 m, 30 Jul 2019, Tuomisto 17962 ( UTCEC! (00001171); isotype: TUR! (mounted on 3 sheets)).

Diagnosis — Similar to and co-occurring with Danaea nigrescens Jenman and D. cartilaginea Christenh. & Tuomisto. Differs from D. nigrescens in always having entire pinna margins (vs serrate to serrulate or very rarely entire); pinnae that are often wider (medial pinnae 3–5(– 7) vs 4–7 times as long as wide without apex), usually parallel-sided (vs often oblanceolate); terminal pinnae often longer than second lateral pinnae distally (vs terminal pinnae usually shorter); and drying green in alcohol (vs brown). Differs from D. cartilaginea in having entire pinna margins or rarely with veins protruding (vs always with veins protruding or serrate); generally smaller size (sterile leaves to 2.2 m vs to 3 m long); generally smaller pinnae (17–43 × 3.6–7.1 cm vs 27–49 × 5–10 cm); margins that are not or only slightly cartilaginous (vs margins usually clearly cartilaginous); thinner texture (vs thick, leathery); genetically differs in locations 105 (T vs G), 377 (T vs C), 446 (C vs T), 480 (A vs C), 614 (A vs G), 620 (C vs T), 1004 (T vs C), 1019 (A vs T) of atpB reference sequence; 698 (C vs T), 752 (A vs G) of rbcL reference sequence; 71 (C vs T), 112 (T vs G), 213 (C vs A), 293 (A vs G), 299 (A vs G), 320 (G vs T), 741–743 (gap vs TTT), 761–762 (gap vs CC), 858 (A vs G), 864 (C vs T), 875 (gap vs C), 885–888 (gap cs TAAA) of trnL-F reference sequence; 109 (G vs A), 153 (A vs C), 334 (C vs A), 471 (T vs C), 517 (T vs C), 617 (A vs C), 630 (G vs A), 642 (A vs G), 643 (G vs A), 670 (A vs G), 673 (G vs A), 684 (C vs A), 688 (C vs T), 877 (T vs C), 909 (C vs T), 958 (C vs T) of rpl32 reference sequence. Danaea kessleri is genetically unique among Danaea in having T (vs A) at position 374 of atpB reference sequence.

Description — Rhizomes creeping, dorsiventral, leaves in two rows, 1.5–5 cm in diam., to at least 20 cm long. Sterile leaves 85–220 cm long; petioles 40–130 cm long, lacking nodes, not winged; laminae 41 × 90 cm, lanceolate, imparipinnate, terminal pinnae shorter or longer than second distal-most pinna-pair (or longest), 4–14 pinna-pairs, medial pinnae 3.5–6.0(–6.5) cm apart, concolorous light green to green or more bluish green adaxially and yellowish green abaxially, texture relatively thin to intermediate, margins sometimes slightly cartilaginous, rachises usually not winged (one seen with wings to 0.2 mm wide); terminal pinnae 18.6–27.1 × 4–6.5 cm, elliptic, lanceolate or oblong, bases acute, apices 1.6–4 cm long, acuminate to almost acute, margins of apices entire (to very slightly sinuate, crenulate or with veins protruding); largest lateral pinnae (17–)21–43 × (3.6–) 4.1–7.1 cm, 2.6–7.0 times as long as wide without apex, widest at or slightly above middle or parallel-sided, bases symmetrical, obtuse to acute, apices 1.1–5 cm long, (long-) acuminate to attenuate, margins of apices entire (to very slightly sinuate, crenulate or with veins protruding); veins 12–23 per cm, mostly forked at costae. Fertile leaves 77 cm long; petioles 47 cm long, no nodes; laminae 30–37 × 8–28 cm, imparipinnate, obovate or parallel-sided, 6–8 pinna-pairs; terminal pinnae 5.5–12 × 1.2–2.2 cm, lanceolate, bases acute, apices cuneate; largest lateral pinnae 10–15 × 1.4–2.2 cm, parallel-sided, bases symmetrical, obtuse or acute, apices 0–0.2 cm long, acute to acuminate, margins of apices entire. Juveniles with terminal pinnae elliptic to lanceolate, lateral pinnae elliptic, pinna apices entire, largest simple juvenile 25 cm long, smallest pinnate juvenile 4 cm long.

Distribution and habitat — Known only from Amazonian Ecuador (Napo and Pastaza) from 100–950 m elevation. Has been found in primary lowland to montane rainforests on clayey and humus rich soils, including hilly terrain and steep slopes. Mentioned as forming dense stands. Fig. 17.

Conservation status — We place Danaea kessleri in the Least Concern (LC) category ( IUCN 2012). It has a known Area of occupancy of 48 km 2, which corresponds to the EN category, and an Extent of occurrence of 12,073 km 2, which corresponds to the LC category. Danaea kessleri seems to be abundant in Amazonian Ecuador and it is known from 18 collections, many of which are inside protected areas (Reserva Forestal Putuyme, Reserva Huella Verde, and Yasuní National Park in Ecuador). There appears to be no imminent threat to all subpopulations.

Etymology — Named for Michael Kessler, who has made big contributions to fern ecology and systematics and who also collected important original material for this species.

Remarks — Danaea kessleri is in many ways morphologically intermediate between D. cartilaginea and D. nigrescens . Genetically it is most closely related to D. nigrescens , from which it differs in having entire pinna margins (vs serrate to serrulate), pinnae that are generally wider (medial pinnae minimum 2.6 vs 4.1 times as long as wide without apex) and usually parallel-sided or elliptic (vs usually oblanceolate), and the terminal pinnae usually being longer than the second lateral pinnae distally (vs terminal pinnae usually shorter). Two samples of D. nigrescens with entire margins are known to us, but these specimens still have narrower pinnae than D. kessleri . The colours of these species seem to behave differently upon drying; D. kessleri dries light green whereas D. nigrescens dries darker, such that D. kessleri preserved with alcohol before drying has the same colour as D. nigrescens that has not been in alcohol, while alcohol treatment turns D. nigrescens into a dark brownish green. The same difference seems to be present between D. kessleri and D. elongata as well (see D. elongata , described above, for further comparison).

Danaea kessleri clearly differs from D. cartilaginea genetically. It also differs in having entire pinna margins that are only seldom slightly cartilaginous (vs usually clearly cartilaginous) and the veins rarely protruding at the apices (vs veins protruding or sometimes apices serrate). In addition, D. kessleri is generally smaller than D. cartilaginea (sterile leaves to 2.2 m vs to 3 m long, sterile pinnae 17–43 × 3.6–7.1 cm vs 27–49 × 5–10 cm) with a thinner lamina texture (vs usually leathery and thick).

Juvenile development differs among Danaea nigrescens , D. kessleri , and D. cartilaginea ; D. nigrescens becomes pinnate at the smallest size (simple juveniles to 8 cm long) and D. cartilaginea at the largest (simple juveniles up to 44 cm long), with D. kessleri being intermediate between the other two (simple juveniles to 25 cm long).

Danaea kessleri differs from the French Guianan endemic D. ushana Christenh. in having generally smaller terminal pinnae (19–27 × 4.0– 6.5 cm vs 26–34 × 4.9–7.8 cm), more pinna-pairs (4–14 vs 3–6 in sterile leaves, 6–8 vs 3–4 in fertile leaves), and rhizomes with leaf bases in two rows (vs leaf bases in 3–5 rows).

Additional specimens examined — ECUADOR: MORONA- SANTIAGO: Mutinza, foothills of Cord. Cutucú just E of village, 02°11'S, 77°44'W, 660–800 m, 19 Nov 1995, Øllgaard 1510 (QCA!); NAPO: km 50 along road traversing Yasuní National Park, 00°43'S, 76°28'W, 200–300 m, 14 Apr 1996, Moran 6164 (AAU!, TUR!); km 21 along road traversing Yasuní National Park , 00°34'S, 76°31'W, 200– 300 m, 16 Apr 1996, Moran 6217 (AAU!, QCA!, TUR!); Yasuní National Park , permanent plot of 50 ha established for study of forest dynamics, 00°40'S, 76°23'W, 250–280 m, 30 Jan 1996, Navarrete 1475 (AAU!, QCA!); Yasuní National Park , permanent plot of 50 ha established for study of forest dynamics, 00°40'S, 76°23'W, 250–280 m, 30 Jan 1996, Navarrete 1486 (AAU!, QCA!); Yasuní National Park , permanent plot of 50 ha established for study of forest dynamics, 00°40'S, 76°23'W, 250 m, 30 Jan 1996, Navarrete 1492 (AAU!, QCA!); Tena –Salcedo highway, trail to Verde Yacu, 01°02'S, 77°52'W, 620 m, 6 Aug 1993, Navarrete 535 (AAU!, QCA!); Near Yasuní Scientific Station , 00°40'S, 76°23'W, 208–250 m, 26 Feb 1995, Svenning 132 (AAU!); Yasuní National Park, W of oil road traversing park, 0–2.1 km from side road leading to Capirón oil well toward SW, 00°42'S, 76°29'W, 200– 300 m, 18 Apr 1997, Tuomisto 10647 (QCA!, QCNE, TUR-2!); Yasuní National Park, W of oil road traversing park, 0–2.1 km from side road leading to Capirón oil well toward SW, 00°42'S, 76°29'W, 200–300 m, 18 Apr 1997, Tuomisto 10653 (QCA, QCNE, TUR!); Yasuní National Park, W of oil road traversing park, 0–2.1 km from side road leading to Capirón oil well toward SW, 00°42'S, 76°29'W, 200–300 m, 18 Apr 1997, Tuomisto 10658 (QCA, QCNE, TUR-2!); Yasuní National Park , between km 38 of oil road traversing park and side road leading to Capirón oil well, 00°40'S, 76°28'W, 200–300 m, 22 Apr 1997, Tuomisto 10821 (QCA, QCNE, TUR!); Yasuní National Park , 2–3 km toward NNE from km 38 of oil road traversing park, 00°38'S, 76°27'W, 200–300 m, 25 Mar 1998, Tuomisto 11934 (QCA, QCNE, TUR!); Yasuní National Park , km 42+2.5 along oil road, 00°42'S, 76°26'W, 200–300 m, 27 Mar 1998, Tuomisto 11956 (QCA, QCNE, TUR-2!); S of Río Napo, 3–4 km E from village Ahuano. Conservation area managed by Selva Viva Organization, 01°04'S, 77°31'W, 400–470 m, 23 Jul 2019, Tuomisto 17897 (HUTI-3!, TUR-3!, UC-2!, UTCEC! (5), Z!); PASTAZA: Reserva Huella Verde, 01°36'S, 77°45'W, 500 m, 31 May 2022, Kessler 15631 (HUTI!, TUR!); Reserva Huella Verde, 01°36'S, 77°45'W, 500 m, 31 May 2022, Kessler 15636 (HUTI!, TUR!); Arajuno Canton, Shuar Wahents Community Territory. Piedmont Evergreen Forest , 00°20' 77°40'W, 750–900 m, 3 Oct 2012, Perez 5795 (QCA!); Reserva Forestal Putuyme, near Madre Tierra, road from Puyo to Pallora, 950 m, 26 Aug 1994, Schneider 500 (Z-2!) .