Spathiphyllum croatii Díaz Jim. & Pérez-Farr., 2021

Jiménez, Pedro Díaz, Pérez-Farrera, Miguel Ángel, Hentrich, Heiko, Domínguez, Héctor Gómez-, Ameca-Juárez, Erasmo Óscar & Aguilar-Rodríguez, Pedro A., 2021, Mistaken identity: a new Spathiphyllum (Araceae) from Veracruz, Mexico, Phytotaxa 522 (1), pp. 56-62 : 58-61

Spathiphyllum croatii Díaz Jim. & Pérez-Farr. , sp. nov. ( Fig. 2 )

Spathiphyllum croatii is morphologically similar to Spathiphyllum cochlearispathum , but it differs from that species in having the petiole twice as long as the blade and not sheathed up to the geniculum (vs. as long as the blade and sheathed near or up to the geniculum), blades 2.0–2.5 longer than wide (vs. three times longer than wide), spadix on a stipe to 8–22 mm long (vs. spadix frequently sessile), individuals up to more than 2 m tall (vs. individuals less than 2 m tall), frequently form large aggregations along lakesides and streams (vs. growing sparsely or forming populations of few individuals in understory).

Type: — MEXICO. Veracruz: Municipio San Andrés Tuxtla , road between Laguna Escondida and Laguna Azul, Vegetación riparia, 18°35’N, 95°05’W, 118 m, 03 April, 2021, Pedro Díaz Jiménez, M . Á . Pérez-Farrera & H . Gómez-Domínguez 1503 (holotype XAL!, isotypes HEM!, UJAT!) .

Terrestrial; understory herb or open areas, frequently form large aggregations with dozens of plants along lakesides and streams. Up to 2.30 m tall; internodes short, to 2.5–5.0 cm diam. LEAVES 61.00– 2.03 cm long; petioles up to twice as long as the blades, 42–145 cm long, 5–10 mm diam., sheathed near the middle, or above to 10–81 cm from the geniculum, the sheath and free portion pale green and covered in white dots, sheath margins entire and wrinkled, inrolled, light green; geniculum 5–9 cm long, 4.5–15.0 mm diam., light green and covered in white dots; blades oblong, oblong-ovate or oblong-elliptic, widest at or just below the middle, 34.0– 70.6 cm long, 16–29 cm wide, approx. 2.0–2.5 times longer than wide, cuspidate at apex, obtuse or rounded at base, subcoriaceous, dark green and glossy above, light green semi-glossy below, drying green to dark brown above, green to light brown and semi-glossy below; midrib sunken and weakly paler above, and covered in white dots, thicker than broad, dark green to yellowishgreen above and light green to whitish below; primary lateral veins, 20–37 pairs, separated 0.6–1.7 cm, arising at a 60–80° angle, sunken and dark green above, light green below; minor veins dark green below. INFLORESCENCE erect, equal to or taller than the leaves, sometimes shorter than the leaves; peduncle 50.0– 200.9 cm long, 4.5–14.0 mm diam.; spathe cucullate, oblanceolate or elliptic, 16.5–34.0 cm long, 8.0– 14.5 cm wide, acuminate apex, subcuneate, attenuate, oblique or obtuse at the base, decurrent 5–16 mm at base, yellowish-green at anthesis, dark green at postanthesis; spadix 3.6–12.2 cm long, 1.6–2.5 cm diam., cream-yellowish, emitting a sweet and pleasant scent at anthesis, stipe 8–22 mm long, 4.0– 7.3 mm diam., light green at anthesis, dark green and finely pale-dotted with white at postanthesis; perianth with 6 free tepals, 1.9–2.8 mm long; 4 or 6 anthers, 1.5–2.4 mm long, thecae oblong, 0.6–1.0 mm; the pistils, sharply emergent, elongate-conic, 5–15 mm long, style 2.5–6.0 mm long, 1.8–2.5 mm diam. at the base; ovary 3-locular, 6–16 ovules per locule, 2–5 ovules per ovary. INFRUCTESCENCE to 9–14 cm long, 2.5–3.3 diam.; berries obovoid to oblong, rostrate, 9–13 mm long, 3.1–6.1 mm wide, yellowish at maturity; seeds oblong, obovoid to irregularly oblique-ovoid, 2.5–3.3 mm long, 1.3–1.8 mm wide, light brown to grayish or dark brown stained and glossy when fresh, dark brown when dry.

Distribution, habitat and conservation status: — Spathiphyllum croatii is endemic to Mexico, known only from the Gulf of Mexico coast in the state of Veracruz ( Fig. 3 ). Due to the vicinity, it is possible that the new species is also in the state of Tabasco. Spathiphyllum croatii grows mainly in open areas of disturbed, riparian vegetation or relicts of evergreen tropical rainforest, between 10 and 900 (–1,000) m. Commonly found on the banks of rivers or lagoons, it forms populations of many individuals. By its distribution area (Extent of Occurrence <1,000,000 km 2 and Area of Occupancy <50,000 km 2) and applying the IUCN Red List Categories and Criteria (B1 and B2), S. croatii is not considered in any protection status ( IUCN 2012), but we highlight that it occurs in highly fragmented habitat, and we still do not know the other populations of this plants outside of the south of Veracruz state.

Phenology: —Flowering occurs throughout the year, but generally with a marked peak at the end of the dry season and early rainy season, between April and August.

Eponymy: —The species is named in honor of the American botanist, Thomas Bernard Croat, an expert on Araceae of the Neotropics. He is currently a curator at the Missouri Botanical Garden and for over 40 years, he has worked on the systematics, ecology, and floristics of Neotropical Araceae . He has described over 1,000 new species and is currently working on the updated revision of Anthurium (1829: 828) , Rhodospatha (1845: 91) , Spathiphyllum , Stenospermation (1858: 70) and Monstera (1763: 470) for Central America.

Additional specimens examined (paratypes):— MEXICO. Veracruz: Mun. Catemaco: In shallow water of pool, Sontecomapan , on road from Catemaco to Montepio , 18°30’00”N, 95°01’48”W, 10 m, 11 Apr. 1952, H. E . Moore 6269 ( BH, GH, MO!); La Palma, 18°33’21”N, 95°03’35”W, 56 m, 07 June 2014, Pedro Díaz Jiménez 1306 ( MEXU!); La Palma, 18°33’N, 95°03’W; 15 m, 03 Apr. 2021, Pedro Díaz Jiménez , M. Á . Pérez-Farrera & H . Gómez-Domínguez 1505 ( HEM!, UJAT!); Road between Tebanca and Miguel Hidalgo, 18°22’N, 94°58’W, 421 m, 04Apr. 2021, Pedro Díaz Jiménez , M. Á . Pérez-Farrera & H . Gómez-Domínguez 1506 ( HEM!, UJAT!). Reserva ecológica “La Otra Opción”, vegetación riparia, 18°22’38”N, 94°55’55”W, 892 m, 15 May 2021, E. C . Sánchez & A. J . Martínez-García 02 ( XAL!) . Mun. Nanchital de Lázaro Cárdenas del Río: Fragmento de selva, 18°03’N, 94°21’W, 50 m, 22 Aug. 2018, Pedro Díaz Jiménez 1438 ( UJAT!) . Mun. San Andrés Tuxtla: Laguna Escondida, 5 km al NW de la Estacion Biologica Los Tuxtlas , acuatica, suelo fangoso, asoc. piper., 18°21’00”N, 95°10’12”W, 160 m, 25 Sep. 1971, R . Hernández & R . Cedillo 1258 ( MEXU!, XALU); Trail to Ejido Laguna Escondida near Estación Biología Los Tuxtlas ., 170–200 m, 28 May 1981, A. H . Gentry & E. J . Lott 32390 ( MO!); Road from Estación Biológica Los Tuxtlas to Playa Montepio ; ca. 7.8 km N of Estación Los Tuxtlas. In forest along stream west of road, 18°34’48”N, 095°09’36”W, 120 m, 29 Sep. 1986, B . Hammel et al. 15506 ( MO!); Along road between Sontecomapan and Estación de Biología Tropical Los Tuxtlas , N of San Andrés Tuxtla , S of Montepio , 5 mi and 2 km E of Estación Biología Tropica Los Tuxtlas. Roadside with water-filled ditches, 18°34’48”N, 095°03’36”W, 50–150 m, 16 Jan. 1987, T. B . Croat & D. P . Hannon 63108 ( MEXU, MO!); 1.5 km NE de la Estación de Biología Tropical Los Tuxtlas. Veg. pastizal., 18°33’36”N, 095°03’36”W, 45 m, 19 July 1994, R . González M . 13 ( MEXU, MO!); Los Tuxtlas: Catemaco - Montepio, Along road between Catemaco and Montepio , 4.7 km S of Los Tuxtlas Field Station, 7.4 km beyond end of asphalt highway, 17.5 km N of Catemaco, 18°36’36”N, 95°03’36”W, 50 m, 25 Aug. 1996, T. B . Croat 78688 ( K, MO!, NY, US) ; Laguna Escondida – Laguna Azul, 18º35’18’’N, 95º05’39’’W, 142 m, 01 Aug. 2014, Pedro Díaz Jiménez 1321 ( MEXU!); Laguna Escondida , 18º35’N, 95º05’W, 137 m, 03 Apr. 2021, Pedro Díaz Jiménez , M. Á . Pérez-Farrera & H . Gómez-Domínguez 1502 ( HEM!, UJAT!); Laguna Azul, 18º35’N, 95º05’W, 142 m; 03 Apr. 2021, Pedro Díaz Jiménez , M. Á . Pérez-Farrera & H . Gómez-Domínguez 1504 ( HEM!, UJAT!) .

Notes: — Spathiphyllum croatii represents the twelfth species for Mexico, and the seventh endemic species, as well as the fifth species for Veracruz and the fourth for the Los Tuxtlas region. Historically, it had been erroneously determined as S. cochlearispathum ( Acebey & Krömer 2008, Croat & Acebey 2015). The later species has shorter petioles, the petiole sheath reaching the geniculum, its blades up to three times as long as wide, and its spadices frequently sessile ( Bunting 1960). In his work, commentary on Mexican Araceae, Bunting (1965) included an unidentified Spathiphyllum from the Los Tuxtlas region and mentioned that a clear difference between that species and S. cochlearispathum was the petiolar sheath, which in the Los Tuxtlas species does not reach the geniculum. No specimens from Los Tuxtlas were included in his revision of Spathiphyllum under the name S. cochlearispathum ( Bunting 1960) .

Spathiphyllum croatii is characterized by having the petiole almost twice as long as the blade, the petiolar sheath not reaching the geniculum, blades about twice as long as wide, and a spadix on a stipe of up to 2 cm. Although S. croatii and S. cochlearispathum have been recorded between 800 and 1,000 m elevation, no sympatric localities are known so far. The former generally grows in lowlands on the banks of rivers or streams in large aggregations (cited as S. cochlearispathum ; Díaz Jiménez et al. 2019b), while S. cochlearispathum has been recorded mostly above 800 m, where it grows sparsely or forming small populations in the understory. In the type locality of S. cochlearispathum grows between coffee crops and in adjacent areas in montane cloud forest, a type of vegetation where S. croatii has not been recorded. This new species grows frequently in riparian vegetation and high evergreen rainforest.

This study highlights the importance of comparing herbarium specimens of species with wide distribution with their type specimens and taking into account morphological traits in living plants in the field. In the opinion of the authors, many species within Mexican aroids are in the reality species complexes, as it seems the case of Spathiphyllum cochlearispathum (Díaz Jiménez unpublished).

Figures

FIGURE 2. Spathiphyllum croatii. A. Adult individuals in flooded site; B. View of the leaf showing the length of the petiole, the end of the sheath (arrow) away from the geniculum and adaxial surface of the blade; C. Inflorescence showing spathe, spadix and elongated stipe (arrow); D. Pistils; E. Mature infructescence showing elongated stipe (arrow); F. Seeds. Photos A, C, D, E, F: P. Díaz Jiménez, B: H. Gómez-Domínguez.

FIGURE 3. Collection sites (black dots) and known distribution of Spathiphyllum croatii at the state of Veracruz.