A new orange-fruited species of Monstera (Araceae: Monsteroideae) from Panama

. Monstera alcirana, endemic to Panamá, is described and illustrated using a color plate based on photographs of the vegetative and reproductive structures of liv-ing material. This species is the fourth of the very small species of Monstera in Central America. It is morphologically similar to M. obliqua , M. minima and M. gambensis but differs by has short internodes, thickly coriaceous blade and peduncle longer than the length of the leaf.


INTRODUCTION
Monstera, a climbing aroid genus best known for its often perforated leaf blades, remains rather poorly understood in the Neotropics as a whole, though progress has recently been made for Mexico and Central America (Grayum 2003;Cedeño-Fonseca 2019;Cedeño-Fonseca et al. 2018, 2020a, 2020b, including the recent publication of several new species in the region:  (Cedeño-Fonseca et al. 2018;Zuluaga & Cameron 2018;Cedeño et al. 2020b;Díaz-Jiménez et al. 2020). Costa Rica and Panama are the centre of diversity of the genus, principally in the Talamanca mountain range below 2300 m elevation (Madison 1977;Cedeño-Fonseca et al. 2020a), and particularly the Caribbean slope.
Hitherto, Monstera obliqua Miq., was the only known species in Costa Rica and Panama with an orange fruiting spadix (Madison 1977;Grayum 2003;Cedeño-Fonseca 2019). This species is most common from the south of Panama, mainly in the Chocó biogeographic region, and throughout the Amazon basin, where orange spadix is more frequent in the genus (Madison 1977). Other species with orange fruiting spadix are Monstera praetermissa E.G. Gonç. & Temponi, endemic to Bahia, Brazil (Gonçalves & Temponi 2004), and Monstera xanthospatha Madison endemic to the Cordillera Occidental and the Cordillera Central of the Andes in Colombia (Madison 1977). Monstera obliqua itself appears to be a large and variable species complex with orange fruiting spadices. Most probably some populations of M. obliqua in the Amazonian basin might be resolved as separate species with further research.
Here we describe and illustrate a new species endemic from Panama with an orange fruiting spadix, and we include an extensive documentation of the populations of M. obliqua in Costa Rica and Panama.

Diagnosis
Monstera alcirana is recognised by its small, entire, thickly coriaceous leaves lacking fenestrations, petioles with deciduous sheath, primary lateral veins arising from the midrib at 35-45°, peduncle longer than the leaf, spathe creamy yellow on both surfaces, and the orange spadix when the fruits are ripe.

Etymology
The species is named in honor of Alcira Pérez de Gómez a Venezuelan botanist from Barquisimeto who did her Master's thesis under the direction of Tom Croat at St. Louis University in St. Louis.

Distribution and habitat
Monstera alcirana is endemic to Panama to the Comarca Guna Yala and Provinces of Coclé, Panamá, Colón and Veraguas, at 350-1000 m, in Tropical wet forest and Premontane rain forest life zones (Holdridge 1967).

Conservation status
Monstera alcirana occurs in nine localities of which four are in protected areas (Chagres National Park, Cerro Gaital Natural Monument, General de División Omar Torrijos Herrera National Park and Santa Fe National Park). The principal threat to this species is the habitat loss due to urban expansion and extensive livestock activities, which were observed mainly in those locations devoid of protection. We calculate an Extent of Occurrence of 9236 km 2 and an Area of Occupancy of 80 km 2 , therefore, we suggest considering M. alcirana as a vulnerable species [VU,B1ab(i,ii,iii,iv)].

Phenology
Flowering has been recorded in January-April, July, November, and fruiting in January-May, and July.

Notes
The new species is a member of sect. Monstera (sensu Madison, 1977), and is unusual in the genus in having leaves that are somewhat like Stenospermation, and indeed the species was long confused with that genus (Gómez, 1983).

Distribution and ecology
Monstera obliqua ranges from Costa Rica to Bolivia, Venezuela, the Guianas, Brazil, and Trinidad & Tobago. In Costa Rica it grows at 0-100 m elevation, in Tropical wet forest life zones, but in Panama it grows at 0-1410 m, in Tropical moist forest, Tropical lower montane wet forest and Montane moist forest life zones (Holdridge 1967).

Phenology
In Costa Rica and Panama, flowering has been recorded in July and November, and fruiting in January, March, July and November.

Notes
The species is a member of sect. Monstera (sensu Madison, 1977), characterized by its small elliptic-lanceolate, inequilateral blades which have entire margins, usually lack perforations, its inflorescences with peduncles that are as long as or longer than petioles (but not the whole leaf) and by its dark orange, small fruiting spadix.
Monstera obliqua in Costa Rica is only known from the southeast Caribbean watershed. It is not common, and possible to find only in primary and secondary forests, at 0-100 m. Most populations have leaf blades without perforations: only the populations in the region of Sixaola have fenestrate blades. This species is the only Monstera with orange ripe fruit in Costa Rica, (Figure 3).
However, the situation for Panama is different: M. obliqua is very common along to the Caribbean slope, at 0-1410 m, growing in Tropical wet forest, Tropical moist forest, Tropical lower montane wet forest, and Montane moist forest life zones (Holdridge 1967). The most common morphotype is one with the leaf blades without perforations similar to the plant from Costa Rica, but the only difference is the much wider altitudinal distribution. (Figure 4-5). Monstera obliqua in Panama grows in rocks where it can develop to the adult phase and producing inflorescences. (Figure 4A-B). Some plants from the Cerro Azul in Panamá have coriaceous leaf blades, with the indistinct primary lateral veins in both surfaces and prominently thick geniculum and peduncles ( Figure 4F-G, 5).
Monstera obliqua has never been recorded for Costa Rica and Panama with perforated and membranaceous   leaf blades. This characteristic is present solely in one morphotype occurring throughout the Amazon basin and which may be a different species since (the type of M. obliqua is not of this morphotype). Madison (1977) speculated that the entire leaf morphotype from Panama (which also occurs in Costa Rica) was probably driven by a limited immigrant line from South America with a consequent decline in genetic variability.