﻿Eugeniasarahchazaroi (Myrtaceae, Myrteae), a new species from the cloud forest of Mexico

﻿Abstract Following the description of Eugenianaraveana in 2016 from the cloud forest of the Cofre de Perote volcano, Mexico, the doubt about the existence of another unlocalized and sympatric species of Eugenia remained. After years of searching, the second endemic species of the Cofre de Perote volcano, Eugeniasarahchazaroi, is presented here. It belongs to the section Umbellatae, and is described, illustrated, and compared with E.naraveana and E.coetzalensis, recently described from Veracruz, the second state with the highest diversity of Eugenia in Mexico. The species is only known from the type locality and is classified in the Critically Endangered CR B1+B2(a,biii) category of the IUCN Red List conservation assessments.


Introduction
Myrtaceae Juss. is a diverse family with ca.6000 species distributed in tropical and subtropical regions (Lucas et al. 2019).It is classified into the subfamilies Psiloxyloideae (with two tribes) and Myrtoideae (with 17 tribes) (Wilson et al. 2005;Wilson 2010;Giaretta et al. 2019;Uc-Gala et al. 2023).From the latter, the tribe Myrteae is the most diverse within the family, with 2690 species (Stevens 2023).About 109 species of Myrtaceae are distributed in Mexico, of which 87 correspond to Eugenia L. (Uc-Gala et al. 2023), a monophyletic genus, one of the most hyperdiverse genera with 1218 species (Giaretta et al. 2022;POWO 2023), and the second largest genus of tree species in the world (Beech et al. 2017;Uc-Gala et al. 2023).
This year, Uc-Gala et al. (2023) performed the most comprehensive checklist of Eugenia species from Mexico.They reported 87 species of Eugenia, 46 endemic to this country.Veracruz is the second state with the highest Eugenia species richness in Mexico, with 31 of them (Uc-Gala et al. 2023).Also, Eugenia occupies the fourth place among the richest tree genera in Mexico (Téllez et al. 2020;Uc-Gala et al. 2023).The species of Eugenia from Veracruz were studied in the taxonomic treatment of Myrtaceae for the Flora of Veracruz series (Sánchez-Vindas 1990).In the last decade, two new and endemic species of Eugenia were described from the same state, E. naraveana Cházaro & Franc.Gut. (Cházaro-Basáñez and Francisco-Gutiérrez 2016), and E. coetzalensis Durán-Esp. & Cast.-Campos (Durán-Espinosa et al. 2018).
After botanical explorations in the Cofre de Perote Volcano in Veracruz, Mexico, a new suspected species of Eugenia is studied here.The aims of this work are: 1) to describe a new species of Eugenia; 2) to compare it with the sympatric and endemic E. naraveana; and 3) to evaluate the conservation status of the species.

Field work
In 2014, during the fieldwork for describing E. naraveana, Macario Córdova-Cortina guided the authors to one population of trees with morphological characters similar to the species collected by Miguel Cházaro-Basáñez in 1987, known as "guayabo" (guajava), but with a different vernacular name, "guayabillo" (small guajava), but it was not explored because it was decided to find the species first collected three decades ago, since both populations were considered to belong to the same taxon, the differences in fruit size being attributed to phenotypic variation.After having described and published the species (Cházaro-Basáñez and Francisco-Gutiérrez 2016), the work of the author mainly focused on the description of the species of Agave (Arzaba-Villalba et al. 2018, 2023) and parasitic Orobanchaceae (Francisco-Gutiérrez et al. 2019, 2023a).In July 2021, during the lockdown of the coronavirus pandemic, the fieldwork was resumed with an expedition by Miguel Cházaro-Basáñez and Héctor Narave-Flores.Finally, the species was found in the locality of Encinal II, municipality of Acajete, Veracruz, Mexico, and subsequent visits were made to collect biological and photographic material.

Taxonomic determination
Fresh specimens of the species were collected, photographed, and dried or preserved in a solution 1:1 of ethanol and water.Measurements were made on living and preserved specimens.Voucher specimens are deposited in the cited herbaria, these cited by the acronyms following Thiers (2023).The sectional placement was determined following the sectional key provided by Mazine et al. (2016).The checklist of accepted species of Eugenia in Mexico (Uc-Gala et al. 2023), the taxonomic treatment of Myrtaceae in Veracruz (Sánchez-Vindas 1990), and articles of recently described species in the state (Cházaro-Basáñez and Francisco-Gutiérrez 2016;Durán-Espinosa et al. 2018) were consulted for taxonomic determination and morphological comparisons.

Conservation assessments
Geographic coordinates were obtained in the field with a Garmin eTrex10 GPS.The data were used to estimate the geographic ranges of the extent of occurrence (EOO) and area of occupancy (AOO) with the Geospatial Conservation Assessment Tool (GeoCAT, Bachman et al. 2011) at the website http://geocat.kew.org/.The obtained values and literature on threats in the species' distribution area were weighted to evaluate the conservation status following the Categories and Criteria of the IUCN Red List of Threatened Species ( IUCN Standards and Petitions Committee 2022).

Distribution map
The polygon of the Cofre de Perote Volcano National Park was extracted from the World Database on Protected Areas and Other Effective Area-based Conservation Measures (WDPA-WDOECM) of the United Nations Environment Programme World Conservation Monitoring Centre (UNEP-WCMC and IUCN 2021), available at https://www.protectedplanet.net/en.Digital elevation models correspond to the layer provided by WorldClim 2.1 (Fick and Hijmans 2017) with resolution of 2.5 min, and the model Continuo de Elevaciones Mexicano 3.0 of the Instituto Nacional de Estadística y Geografía (INEGI) of Mexico with resolution of 130 m, available at https://www.inegi.org.mx/app/geo2/elevacionesmex/.Map was designed in QGIS 2.15 (QGIS Development Team 2016).
Phenology.The species was collected with floral buds, flowers, and mature fruits from April to July.
Etymology.The specific epithet honors Sarah Magyari Cházaro-Hernández, the beloved daughter of Miguel Cházaro-Basáñez, who has accompanied him on numerous botanical expeditions.As a child, Sarah Cházaro developed an interest in botany by learning to identify several plant genera on field trips with her father (Fig. 4).This new species is the third dedicated to his children, with Agave paskynnellchazaroi Arzaba, Cházaro & Franc.Gut. (Arzaba-Villalba et al. 2023), and Valeriana rudychazaroi Cházaro, Franc.Gut.& J.R.Carral (Francisco-Gutiérrez et al. 2023b).These eponyms were the last will of Miguel Cházaro before he passed away on April 04, 2023.The obituary with a review of his life and work can be found in Francisco-Gutiérrez and Vázquez-García (2023).Conservation status.The species has geographic ranges of Extent of Occurrence (EOO) of 0 km 2 , and Area of Occupancy of 4 km 2 .The species grows in the foothills of the Cofre de Perote Volcano, about 7.5 km from the limit of the protected area under the national park category (Fig. 3), a location that threatens it because the vicinity of the volcano has experienced constant overexploitation of forests and illegal logging since the 20 th century (Hoffmann 1989).Because of EOO < 100 km 2 , AOO < 10 km 2 , number of locations = 1, and continuing decline observed in the extent and quality of habitat, we evaluate the new species E. sarahchazaroi in the category critically endangered CR B1+B2(a,biii).This species is currently the target of conservation efforts being reproduced in the greenhouses of the Secretary of Environment and Natural Resources (SEDEMA) of Veracruz.
Discussion.Eugenia sarahchazaroi belongs to the section Umbellatae through having bracteoles and calyx lobes not foliaceous, calyx open in the bud, and flowers 4-merous arranged in fascicles.This section has the largest species richness in Eugenia, with about 680 species (Mazine et al. 2016).
The species of Eugenia from Veracruz, Mexico, were studied in the issue of Myrtaceae of the Flora of Veracruz series (Sánchez-Vindas 1990).These species were considered for the morphological comparisons with E. naraveana (Cházaro-Basáñez and Francisco-Gutiérrez 2016), the most similar species.Besides, only the species E. coetzalensis was later described for Veracruz.Because of it, the new species presented here is compared with both.
Eugenia sarahchazaroi is distinguished from E. coetzalensis mainly by the type of inflorescence (fascicle vs. racemes, respectively).The paratype of E. coetzalensis, E. Guízar-N.& J.C. Echeverría 5688 (MEXU1075426) can be electronically consulted at https://datosabiertos.unam.mx/IBUNAM:MEXU:1075426. Eugenia sarahchazaroi is similar to E. naraveana but it differs in several morphological characters, which can be analyzed in the Table 1.Overall, this new species' leaves, pedicels, hypanthium, staminal discs, and fruits are smaller than those of the E. naraveana.Additionally, the number of leaves and fruits are notably higher than in E. naraveana, as seen in photographs of Fig. 2. The staminal disc also shows a suppressed central area with no stamens where the style inserts, which is lacking in the staminal discs of E. naraveana.These features allow us to determine this taxon as a different species.

Figure 1 .
Figure 1.Eugenia sarahchazaroi A inflorescence B twig with fruits C detail of flowers D fascicles E floral buds F staminal disc G adaxial surface of a leaf H abaxial surface of a leaf I immature fruit J ripe fruit, and K seedling.All photographs were taken by Rodrigo Carral-Domínguez and edited by Antonio Francisco-Gutiérrez.

Figure 2 .
Figure 2. Morphological comparison between Eugenia sarahchazaroi and E. naraveana.All photographs of E. sarahchazaroi were taken by Rodrigo Carral-Domínguez; photographs of E. naraveana were taken by Antonio Francisco-Gutiérrez, except for the branch with fruits by Jose Luis Ramírez-Pacheco.

Figure 3 .
Figure 3. Distribution map of Eugenia sarahchazaroi and similar species in Mexico.The colored square corresponds to the Cofre de Perote volcano and its natural protected area under the category of National Park, delimited with the yellow line.

Figure 4 .
Figure 4. Miguel Cházaro and his beloved daughter, Sarah M. Cházaro-Hernández A learning her first botanical knowledge at three years old at home B botanical expedition in El Chico National Park, Hidalgo, Mexico, in 2018.Photographs taken by Patricia Hernández-Romero.

Table 1 .
Morphological comparison among Eugenia sarahchazaroi and similar species E. naraveana and E. coetzalensis.