Three new species and a new record of Monstera Adans. sect. Marcgraviopsis Madison (Araceae: Monsteroideae: Monstereae) from the Caribbean watershed in Costa Rica and Panama

. Three new species from Monstera sect. Marcgraviopsis , M. caribaea M.Cedeño, O.Ortiz & A.Hay, M. lamersiana M.Cedeño & A.Hay and M. panamensis M.Cedeño & O.Ortiz, are described, and new record of M. guzmanjacobiae Díaz Jim. et al. for Costa Rica is reported here. The new species are compared with the most similar described species with shingling juveniles, and illustrated from living plants.


INTRODUCTION
The genus Monstera has been considered one of the most taxonomically difficult Neotropical groups within the Araceae, despite its relatively small size compared to the giants Anthurium and Philodendron whose species are estimated to number in the thousands (Grayum 2003;Boyce and Croat, 2011 onwards;Cedeño-Fonseca et al. 2022).It is represented by approximately 52 species in Central America, which are distributed in wet tropical forested regions at low to medium elevations, from 0-2300 m above sea level (Grayum 2003;Cedeño-Fonseca et al. 2021;Croat et al. in progress).Nearly all are appressed-climbing hemi-epiphytes or nomadic vines (Zotz 2013;Sperotto et al. 2020).
Monstera Adans.has been divided into four formal sections (Madison 1977): section Echinospadix Madison (1 sp.), section Marcgraviopsis Madison (up till now 11 spp.), section Tornelia Madison (3 spp.) and section Monstera (37 spp.) (Cedeño-Fonseca et al. 2020, 2022).Work on fuller systematic understanding of this genus is now much progressed but still ongoing, and, although a valuable preliminary molecular phylogenetic analysis of the Monstereae has been made (Zuluaga et al. 2019), indicating among other things that Madison's sections in Monstera are partly unnatural, a complete molecular phylogenetic analysis is not yet available to provide the appropriate level of certainty for a revised infrageneric classification to be developed (Cedeño-Fonseca et al. 2022).We therefore persist with Madison's sections for now.
Section Marcgraviopsis is characterized by the earliest climbing phase having the leaf blades themselves closely appressed to the substrate (often termed 'shingle plants') with petioles that are less than half as long as the blades (Madison 1997).The great majority of the species in this section are Central American, and a mere four of them also occur in South America: the widespread Monstera spruceana (Schott) Engl.and M. dubia Nevertheless, we note here, in passing, that species of the exclusively South American, almost entirely Amazonian Monstera subpinnata Engl.-M.barrieri Croat, Moonen & Poncy complex also have appressed shingling juveniles, but of somewhat distinct morphology from the juveniles of sect.Marcgraviopsis [the most obvious, but not the sole difference being the shingling blades held obliquely upward, versus the more usual obliquely downward posture of sect.Marcgraviopsis shingling blades].These species have never been placed in sect.Marcgraviopsis, we presume because, in spite of their radical and abrupt differentiation from the adult form, the heteroblastic juveniles have not been noted until relatively recently, and appear to be unrepresented in herbarium collections.The infrageneric placement of this complex also awaits fuller resolution of phylogenetic relationships within the genus, and more detailed description of their heteroblastic phases will form part of a forthcoming commentary on morphological diversity in Monstera (Cedeño-Fonseca et al., in prep.).
Despite the recent taxonomic revision of Monstera for Costa Rica by Cedeño-Fonseca et al. (2022) and for Central America as a whole by Croat et al. (in progress), new species of the genus are still being documented along the Cordillera Volcanica Central in Costa Rica and the Cordillera de Talamanca between Costa Rica and Panama.High intraspecific variation within populations and the fragmentary nature of herbarium samples hampers the establishment of evident morphological characters needed for the accurate identification of all species (Grayum 2003;Cedeño-Fonseca et al. 2022).Furthermore, populations encountered in the field only in the sterile state have impeded fuller understanding of species limits.Documentation in the natural state of morphological characteristics of seedlings, juveniles, and adult fertile plants has been essential.
Fieldwork conducted between 2015 and 2021 aimed to document Monstera in different regions in Mexico, Costa Rica and Panama, as part of the the first author's master's thesis (Cedeño-Fonseca 2019).However, some populations of the genus found in the Caribbean of Costa Rica and Panama could not be identified or included within the range of variation of species already described for Central America.With further observations, we consider that three such taxa represent undescribed species from the Caribbean watershed between Costa Rica and Panama, and a fourth is a new record for Costa Rica of a species recently described from Mexico (Díaz- Jiménez et al. 2020).
We therefore describe and illustrate these three new species belonging to the sect.Marcgraviopsis based on morphological evidence, and newly record Monstera guzmanjacobiae Díaz Jim.et al., from the same section, for Costa Rica.
Photographs of living plants were taken with a Nikon COOLPIX P530 and also mobile phones with integrated high-resolution cameras, such as Huawei Y7 and Huawei p20.Measurements were made on herbarium specimens and living plants in the nature.Due to the high demand for aroid species as ornamental plants, Three new species and a new record of Monstera Adans.sect.Marcgraviopsis and a rapidly growing black market that endangers native populations (even in protected areas), coordinates are here omitted from all specimen citations, and no distribution maps are provided.Stated life zones follow the terminology of Holdridge et al. (1971).

Etymology
The species epithet refers to the Caribbean coast, where the new species was first discovered.

Phenology
Flowering time is unknown but fruiting was recorded in January and March.

Notes
The species is a member of sect.Marcgraviopsis.It differs from other species of the section by its appressedclimbing and pendent habit, highly variable blades with the presence of lobes and perforations, but sometimes restricted to only one side of the blade, and the erect inflorescence with short peduncle <5 cm long.The hanging stems of Monstera caribaea that connect to the ground are similar to the adult individuals of M. pittieri, mainly in that some have perforations in only one margin of the blade.

Etymology
This species is named in honour of Gijsbertus Lamers, who has generously supported exploration of both Monstera and Philodendron in Central America.

Distribution and habitat
This species is endemic to Costa Rica.It is currently known only in the region of Muelle de San Carlos, at elevations of ca.40-300 m, in the Caribbean slope.It occurs in Tropical wet forest life zones, in primary forests.

Phenology
Flowering time is unknown but fruiting was recorded in January.

Notes
The species is a member of sect.Marcgraviopsis.It differs from the other species of the section by its internodes 3-14 cm long with longitudinal striations, its smooth dark green petiole striated at the base and adaxially flattened; its deciduous petiole sheath, and almost terete geniculum; the lanceolate leaf blade, rounded or subcordate at the base, with the apex obtuse; and the ripe infructescence on a hanging peduncle with the stylar layer green and the pulp white.Monstera lamersiana usually has pinnatilobate leaves, with the basal lobes connected to each other by filaments.Another characteristic of M. lamersina is that some individuals have the leaf blade with an entire margin and without perforations.These occur sympatrically with populations of individuals with pinnatilobed and fenestrate blades.

Diagnosis
Monstera panamensis is most easily confused with M. molinae and M. spruceana, but it differs from M. molinae in having larger leaves on adult plants (20-45 cm to long vs. 10-30 cm long), pinnatilobed and with perfora-tions (vs.completely pinnatilobed without perforations), and the style hexagonal, distally slender and cylindrical, and strongly projecting, (vs. a distally square, cylindrical or hexagonal projecting style).It differs from Monstera spruceana in having inflorescences on free hanging stems (vs. on attached ascending stems), the petiole completely smooth (vs.smooth or warty), the petiole sheath deciduous without fibrous remnants (vs.deciduous with fibrous frag- ments), and style hexagonal and strongly projecting and cylindrical distally (vs.style hexagonal and not raised).

Etymology
The epithet is drawn from the Republic of Panama, and alludes to the species' origin.

Distribution and habitat
This species is endemic to Panama, at elevations of 0-850 m, on the Caribbean and Pacific slope.It occurs in Tropical wet forest and Premontane rain forest life zones, in primary forest.

Phenology
Flowering time is unknown but fruiting was recorded in September and November.

Notes
The species is a member of section Marcgraviopsis.It is distinguished by its lengthy internodes up to 15 cm long, the pinnatilobed adult leaf blade, the smooth petiole, sheathed up to the base of the geniculum, short peduncles (<6 cm), long spadices (14-15 cm), and a hexagonal, strongly projecting, and distally cylindrical style.
J.P Folsom 6207 (MO) was long confused with M. molinae.However, due to differences that could be observed in the flowers in the herbarium sample, fieldwork was carried out to examine the populations in their natural state, with the result that this collection is here redetermined as M. panamensis.The majority of populations of M. panamensis from the Caribbean lowlands have not been seen with reproductive structures.The species is characterized by its habit with appressed-climbing and pendent shoots, terete stems, light-green, smooth, dorsiventrally compressed petioles each with a projecting ligule up to 3.0 cm long, adult leaf blades with 1-4 fenestrations often only on one side, or without perforations, and flowers with a conical pyramidal style (Díaz-Jiménez et al. 2020).Monstera guzmanjacobiae was described as endemic from Los Tuxtlas (Veracruz, Mexico) and it has never been collected in other localities apart from the municipality of Catemaco (Díaz-Jiménez et al. 2020).Plants from Mexico and Costa Rica display rather wide ecological amplitude, generally growing on the edge and interior of the forest, as well as in abandoned areas with secondary vegetation.(Fig. 4).
At present, Monstera guzmanjacobiae is only known to occur in Mexico and Costa Rica.This disjunct geographic distribution may be related to the relative lack of sampling of the Araceae in general and Monstera in par- (Kunth) Engl.& K.Krause along the northern Andes and Amazonia, and M. pittieri Engl.and M. filamentosa Croat & Grayum reaching only into the Department of Chocó in northwestern Colombia close to Panama.
This species is endemic to the southern Caribbean slopes of Costa Rica and western Caribbean slope of Panama, at 20-25 m elevation.It occurs in Tropical wet forest life zones, in open areas.

Figure 1 .
Figure 1.Monstera caribaea.A. Adult plant, leaf-blades perforated and with 2-5 lobes per side.B. Adult plant, the leaf-blade entire and with 2 or 5 lobes per side.C. Hanging stem leaf-blade with 2 or 3 perforations on one side.D. Juvenile plant appressed to the host tree.E. Hanging stem with erect inflorescence in development.F. Climbing stem with infructescence in development.Photos by Marco Cedeño-Fonseca.M. Cedeño & A. Hay 1615 (USJ).

ACKNOWLEDGMENTS
This contribution represents part of the Master´s thesis of Marco Cedeño-Fonseca, successfully completed in the Programa de Posgrado en Biología at Universidad de Costa Rica.He thanks the Art into Acres initiative for their support in the project to document the genus Monstera in the Neotropics, Missouri Botanical Garden for an Alwyn H. Gentry Fellowship, the Society of Systematic Biologists (SSB) for a Mini-ARTS research grant, the Organization for Tropical Studies for a Glaxo-Wellcome research grant, the Rexford Daubenmire fellowship, and La Tirimbina

Figure 4 .
Figure 4. Monstera guzmanjacobiae.A. Adult plant ascending on a tree and with hanging stems.B. Hanging stem with erect infructescence in development (note: divided upper left leaf is of M. filamentosa).C. Developing infructescences on ascending stem.D. Developing infructescences with pyramidal and conical style.Photos by Marco Cedeño-Fonseca.M. Cedeño & J.M. Hughes 2205 (USJ).