Magnolia cirorum A.Vázquez, S.Estrada & D.Aguirre, 2023

Vázquez-García, J. Antonio, Estrada, Sergio, Martínez, Abraham Heriberto, Aguirre, Donovan, Cubas, Kelvin & Muñiz-Castro, Miguel Á., 2023, Magnolia cirorum (Magnolia sect. Talauma, Magnoliaceae), a new species from Pico Bonito National Park, Atlántida, Honduras, Phytotaxa 629 (2), pp. 129-138 : 130-137

Magnolia cirorum A.Vázquez, S.Estrada & D.Aguirre sp. nov. ( Figs 1–6 ).

Type: HONDURAS. Atlántida: Parque Nacional Pico Bonito, Las Camelias community creek, 15°39’1” N, 87°0’13” W, 214 m, 16 May 2023 (fl & fr), Navarro 1601 (holotype: CURLA!; isotypes: IBUG!, TEFH!) .

Magnolia cirorum differs from M. cochranei in its smaller flowers, 4.0–6.8 vs. 10.0– 12.5 cm; shorter sepals, 2.2–2.6 vs. 6.0–7.0; shorter petals, 2.5–3.3 vs. 6.8–7.0; fewer stamens, 22–30 vs. 72–82; and shorter fruits,3.3–4.4 vs. 5.0–7.0 cm. It also differs from M. quetzal in having smaller flowers 4.0–6.8 vs. 7.1–7.9; shorter sepals, 2.2–2.6 vs. 3.4–3.8; shorter petals, 2.5–3.3 vs. 3.4–3.8; fewer stamens, 22–30 vs. 42, carpels with deciduous styles vs. persistent; shorter fruits, 3.3–4.2 vs. 7.0– 7.5 cm.

Trees 15.0–18.0 m tall, DBH 30–40 cm; outer bark rough, light greyish. Twig internodes 0.3–2.0 × 0.3–0.5 cm, glabrous, green, with elliptic lenticels. Petioles 1.5–4.0 cm; stipules adnate to the entire length of the petiole, glabrous; leaf blades elliptic, or lanceolate to oblong, 8.0–15.0 × 5.0–7.5, acute to rounded at the base and apex, glabrous; leaf secondary veins 8–10 per side. Flower buds white 2.0–2.5 × 1.0– 1.2 cm; flowers white to creamy white, fragrant, trimerous, 4.0– 6.8 cm in diam., fragrant. Sepals 3, white to creamy white, 2.2–2.6 × 1.2–1.6 cm, oblong to spatulate, slightly reflexed in male phase, concave in the upper third of their length; outer petals 3, white, 2.8–3.3 × 1.3–1.7 cm, oblanceolate to spatulate, concave in the upper third of their length; inner petals 3, white, 2.5–2.9 × 0.8–1.1 cm, oblanceolate to spatulate, concave in the upper third, alternating in arrangement with the outer petals; stamens 22–30; fruit ellipsoid, ovoid to rhomboid, fruit length 3.3–4.2 cm, fruit diam. 2.3–3.2 cm, fruit weight 8.5–9.0 g; styles deciduous, carpels 6–10, glabrous, dehiscence circumscissile. Seeds red, 8–11 × 6–8 × 5–7 mm, 1–2 per carpel, seed weight 95–100 mg.

Eponymy and ethnobotany:— In honour of Ing. Ciro Amed Navarro-Cruz and his son Ciro Vladimir NavarroUmaña, outstanding contributors to research, conservation, and sustainable management of Pico Bonito National Park, co-managed by FUPNAPIB. Magnolia cirorum timber is used by local people in carpentry to make furniture, and its wood has good physical and ornamental characteristics, with broad dark brown heartwood and yellow sapwood. For this reason, it is known locally by the name of redondo negro (black orbed). Untreated wood has resisted pests without damage for more than 15 years (Kelvin Cubas’ father, pers. comm.).

Phenology:— Flowering February–June, fruiting March–August. According to Abraham H. Martínez (pers. comm.), this year (2023) has been climatically unusual, as it is affected by the El Niño-southern oscillation phenomenon, in which hydric stress is triggering flowering in many tree species, including M. cirorum .

Distribution, habitat, and ecology:— Found on well-drained, north-facing slopes in the tropical evergreen rainforest, 190–300 m a.s.l. Collected on the lower slopes of Pico Bonito in forest and agroforestry areas of Las Camelias, municipality San Francisco. The soil had a clay loam texture with little organic matter. The dominant accompanying tree species of M. cirorum in the type locality are mahogany or caoba ( Swietenia macrophylla , Meliaceae ), palo Santa María ( Calophyllum brasiliense , Clusiaceae ), San Juan ( Vochysia hondurensis , Vochysiaceae ), Rosita ( Hieronyma alchorneoides , Phyllanthaceae ), sangre ( Virola Koschnyi , Myristicaceae ), and varillo ( Symphonia globulifera , Clusiaceae ). The pollination syndrome is cantharophily; Nitidulidae beetles were observed in two flowers during the female phase. Anthesis is possibly nocturnal, and sepals open before the petals. The presence of termites (Isoptera) in the adult tree bark of this Magnolia species has been observed. On the ground, dry, empty seeds have been found, apparently eaten by ants (Hymenoptera) and termites. Ants were seen on bark, leaves, and branches, and leaves were eaten by Lepidoptera caterpillars. No evidence of regeneration has been found, and still developing, immature fruits were observed on 16 May 2023.

Conservation status:— Because this species is known only from the type locality, where there are only five trees, it must be a target for conservation and research efforts. This site is outside the Pico Bonito National Park core zone, in the lowlands of the buffer zone, and thus the species is not directly protected and exposed to several threats. The pattern of threat observed for other Magnolia species, in which about 80% of species are threatened ( Rivers et al. 2016, Vázquez-García et al. 2013a), is repeated for M. cirorum . Accordingly with the IUCN Red List criterion B2 (AOO <10 km 2) and conditions ab(iii) ( IUCN 2022), the species could be considered Critically Endangered (CR). Additionally, due to its rarity and narrow distribution (condition a), this species experiences a continuing decline in area and quality of habitat (condition b(iii)) due to deforestation and the introduction of crops such as African palm and exotic fruit trees. The first step in the recovery started with trials of about 300 seeds collected by Abraham Martínez, Inga Foundation, to define a germination protocol for the species.

Additional specimen examined:— HONDURAS. Atlántida: Pico Bonito National Park, Las Camelias community creek, 15°39’0.83” N, 87°0’14.04” W, 199 m, 3 Jun 2023 (fl & fr), Vázquez-García 10265 ( CURLA, IBUG, TEFH) ; Pico Bonito National Park, Las Camelias community creek, 15°38’59.71” N, 87°0’16.56” W, 197 m., 3 Jun 2023 (fl & fr), Aguirre 1 ( CURLA, IBUG, TEFH) ; Pico Bonito National Park, Las Camelias community creek, 15°39’0.29” N, 87°0’14.4” W, 200 m, 3 Jun 2023 (fl & fr), Navarro-Cruz 1602 ( CURLA, IBUG, TEFH) .

Notes:— Magnolia cirorum belongs to the M. sect. Talauma , subsect. Talauma because it has stipules adnate to the petiole and circumscissile dehiscence. Magnolia cirorum is the third species in Honduras of the Stenopetalae group ( Rea et al. 2022), along with M. cochranei and M. quetzal . With the discovery of M. cirorum , the number of Honduran endemic species of Magnolia increased to eight distributed in four distant regions: 1) Cusuco National Park: M. cochranei , M. cusucoensis A.Vázquez & D.L.Kelly (2022: 121) ; M. darioi A.Vázquez & D.L.Kelly (2022: 123) , and M. pastorcortesii A.Vázquez & D.L. Kelly (2022: 129) ; 2) Pico Bonito National Park: M. cirorum and M. atlantida ; 3) Pico Pijol National Park: M. cochranei , M. picopijolensis A.Vázquez (2022: 133) ; and 4) Montañas de Celaque National Park: M. celaquensis A.Vázquez & H.Vega (2022: 115) ( Vázquez-García et al. 2022). Each region demands an urgent local communal strategy involving forest producers, botanical gardens, academic institutions, and governmental authorities to further assess through field surveys their current in situ and ex-situ conservation status and develop specific plans for population and habitat recovery to ensure the survival of these species currently in high risk of extinction. Without regeneration at Las Camelias creek, the only known location of M. cirorum , the species is at high risk of extinction. Further exploration is urgently needed in the higher portion of the steep gradient at Las Camelias because larger populations could be found there.

Navarro-Cruz et al. (2019) reported three species (or morphospecies) of Magnolia from transect 2 at PBNP: M. cochranei , M. sp. (Navarro, personal communication, presumably M. sororum , a species with abaxially brown, felty leaves) and M. sp. (with gigantic leaves), presumably M. atlantida . However, the authors have not confirmed the taxonomic identity for any of these taxa and thus further fieldwork to obtain fertile specimens is urgently needed.

House et al. (2006) reported M. mexicana De Candolle (1817: 451) from Pico Bonito National Park, cited as Talauma mexicana from transect 6 (Corozal Mountain) in montane elfin forest and transect 8 (Los Hornitos Mountains) in evergreen broadleaved forest (submontane rainforest). Similarly, Navarro-Cruz et al. (2019) reported M. mexicana for transect 3 of PBNP. However, this species is confined to central México (Veracruz and Puebla), and no records have been confirmed from Central America. Thus, we need to obtain flowering and fruiting material.

Figures

FIGURE 1. Updated distribution of Honduran Magnoliaceae including Magnolia cirorum.

FIGURE 2. Magnolia cirorum in lowland evergreen tropical rainforest dominated by Vochysia. Photographs by A.H. Martínez.

FIGURE 3. Magnolia cirorum.A, B.Tree.C.Bark.D. Flower at the female phase with a Nitidulidae beetle.E.Close-up of anundetermined Nitidulidae beetle, right-side-up and upside down. Photographs A & B by M.A. Muñiz; C by A. Vázquez; and D & E by D. Aguirre.

FIGURE 4. Magnolia cirorum. A. Flower bud covered by a second spathaceous bract. B. Flower bud covered by sepals. C, D. Sepals start to separate from petals at the female phase. E, F. Sepals are in the process of becoming fully reflected, still in the female phase. G, H. Flowers fully open past the male phase, without stamens left. Photographs A, C, F & H by A.H. Martínez; B, E. & G by D. Aguirre; and D. by A. Vázquez.

FIGURE 5. Magnolia cirorum. A. Fruit before dehiscence. B. Fruits before maturity of seeds. C–G Stages of circumscissile dehiscence. Photographs, A by D. Aguirre; B & E by A.H. Martínez; and C, D & F by A. Vázquez.

FIGURE 6. Magnolia cirorum. A, B, D. Leaf variability. C, E, F. Gynoecium and stamens at male-phase. G. Sepals and petals. H. Immature seeds. I, J Mature seeds. K. Scarified seeds with a black seed coat. Photographs A & H–K by A.H. Martínez; and B–G by A. Vázquez.