Spathiphyllum wilfridianum Díaz Jim., 2022

Jiménez, Pedro Díaz, Dötterl, Stefan, Fuchs, Roman, Hentrich, Heiko, Pérez-Farrera, Miguel Ángel, Vega, José Padilla & Aguilar-Rodríguez, Pedro A., 2022, Two new species of Spathiphyllum (Araceae) from Tabasco, Mexico with notes on their floral scent, Phytotaxa 566 (1), pp. 121-132 : 126-128

Spathiphyllum wilfridianum Díaz Jim. , sp. nov. ( Fig. 4 )

Spathiphyllum wilfridianum is morphologically similar to S. cochlearispathum , but differs from that species in having petioles longer than the blades and sheathed to 33–54 cm from the geniculum (vs. as long as the blade and sheathed near or up to the geniculum), sheath margins entire (vs. wrinkled), blade attenuate at the base (vs. rounded), primary veins rising at an angle of 40–55° (vs. 60–80°), and up to 7 ovules per ovary (vs. up to 16).

Type: — MEXICO. Tabasco: Municipio Centro, communal land Dos Montes, Centro de Interpretación y Convivencia con la Naturaleza “Yumka”, 17°45’N, 92°45’W, 7 m asl, 16 November 2009, Pedro Díaz Jiménez & A . Garduza 1092 (holotype UJAT!) .

Terrestrial; understory herb, up to 2.15 m tall; internodes short, up to 6 cm diam. LEAVES 122–167 cm long; petioles up to twice as long as the blades, 70–104 cm long, 6–8 mm diam., sheathed near the middle, or above to 33–73 cm from the geniculum, free portion terete, the sheath and free portion pale green and covered in white dots, sheath margins entire, light green or dark green; geniculum 2.5–5.3 cm long, 7–9.5 mm diam., light green and covered in white dots; blades oblong or oblong-elliptic, widest almost in the middle, 50.0– 65.5 cm long, 14–29 cm wide, approx. 3 times longer than wide, acuminate at apex, attenuate (rarely sub-rounded) at the base, subcoriaceous, dark green to yellowishgreen and semi-glossy above, light green semi-glossy below, drying green dark to dark brown above, greenish-brown to light brown and below; midrib sunken, dark green above, and covered in white dots, light green to whitish below, thicker than broad; primary lateral veins, 24–30 pairs, separated 7–20 mm, arising at a 40–55° angle, sunken and dark green above, whitish below; minor veins dark green below. INFLORESCENCE erect, taller than the leaves; peduncle 139–168 cm long, 5.5–8.5 mm diam., covered in white dots, green to light yellowish-green; spathe cucullate, oblong or oblong-elliptic, 24–40 cm long, 12–15 cm wide, acuminate apex, subcuneate or attenuate, and oblique at the base, almost not decurrent on the peduncle, yellowish-green at anthesis, dark green at post-anthesis; spadix 11–13 cm long, 2.0– 2.5 cm diam., cream-yellowish, emitting a sweet and pleasant scent at anthesis, stipe short, 5–8 mm long, 6 mm diam., yellowish-green at anthesis, yellowish-green at anthesis; perianth with 6 free tepals, 1.5–2.5 mm long; 6 anthers, 3.5–4.0 mm long, thecae oblong, 1.0– 1.8 mm; the pistils, sharply emergent, conic, 5–7.3 mm long, style 1.8–3.1 mm long, 1.3–1.5 mm diam. at the base; ovary 3-locular, 1–4 ovules per locule, 4–7 ovules per ovary. INFRUCTESCENCE 18–21 cm long, 2.5–3.3 cm diam.; berries obovoid to oblong, rostrate, 10–17 mm long, 3.3–6.0 mm wide, yellowish at maturity; seeds oblong to oblique-ovoid, dark to dark brown when dry and glossy when fresh.

Distribution, habitat and conservation status: — Spathiphyllum wilfridianum is only known from the Centro de Interpretación y Convivencia con la Naturaleza “Yumka”, Tabasco ( Fig. 1 ). Only three adult individuals and four juveniles were found growing as an understory species in a flooded site in evergreen tropical forest, at 7 m asl in this protected natural area. Due to the low number of individuals found, the introduced exotic fauna (such as the deer, Axis axis ), which often destroys the herbaceous vegetation of the understory, and according to the IUCN Red List Categories and Criteria, the species can be considered as critically endangered [CR B2ab(ii,iii,iv,v); IUCN 2012].

Phenology and floral scent: —The specimens at anthesis and with infructescence were collected in November. Flowering in cultivated plants (plants cultivated since 2009 when they were still juveniles and removed with the complete rhizome) has been recorded in March, June, and November. The spadices of S. wilfridianum emitted a strong and pleasant floral scent, most intense between 6:00 and 12:00 AM. A total of 25 compounds was detected in the two samples (20 terpenoids, three aromatics and two lipid-derived compounds; Appendix 2). The main compounds (> 5% in any sample) were (E)- β -Farnesene, (E)-Nerolidol, Methyl benzoate, α -Terpineol, and Eucalyptol (Appendix 2). (E)- Nerolidol is reported in this study for the first time as a main compound in Spathiphyllum ( Hentrich et al. 2010; Díaz Jiménez et al. 2019; 2021b).

Eponymy: — Spathiphyllum wilfridianum is named in honor of the Mexican scientist, Dr. Wilfrido Miguel Contreras Sánchez, a Mexican professor at the Universidad Juárez Autónoma de Tabasco (UJAT). During his time as Faculty Director at the Division of Biological Sciences (DACBiol), he aided and supported the studies of the Araceae in the state of Tabasco, helping students to attend national and international conferences. Dr. Wilfrido is currently Secretary for Research, Graduate Studies, and Relations at the UJAT. His main line of research is fish reproduction and sexual inversion.

Additional specimens examined (paratypes):— MEXICO. Tabasco: Mun. Centro, ejido Dos Montes, Centro de Interpretación y Convivencia con la Naturaleza Yumka, 17°45’, 92°45’, 7 m, 16 November 2009, Pedro Díaz Jiménez & A . Garduza 1093 (MO!). Mun. Comalcalco, R / a. Independencia 2da. Sección (cultivated), 18º17’N, 93º09’W, 8 m, 09 Mar 2021, Pedro Díaz Jiménez 1496 ( UJAT!) .

Notes: — Spathiphyllum wilfridianum had been mistakenly identified as S. cochlearispathum . However, S. wilfridianum has a petiole almost twice as long as the blade and is sheathed almost to the middle, the margin of the sheath is entire and not wrinkled, its blades are narrower with an attenuated base (rarely sub-rounded), the angle of the primary veins is less than 60°, and the number of ovules per ovary is less than that recorded in S. cochlearispathum ( Bunting 1960, Díaz Jiménez et al. 2021a). Spathiphyllum wilfridianum is a rare species, only known from its type locality, growing below 10 m asl in tropical forests, while S. cochlearispathum has been collected mostly above 800 m asl in coffee crops and montane cloud forests ( Díaz Jiménez et al. 2021a). The new species represents the fourteenth species for Mexico and the third species for Tabasco ( Díaz Jiménez et al. 2021a, Croat et al. unpubl.). On the other hand, unlike S. maldonadianum , S. wilfridianum has entire sheath margins, shortest geniculum, narrower blades with attenuated base, fewer pairs of primary veins per side, shortest pistil, and fewer ovules per ovary.

We strongly recommend that all specimens identified under S. cochlearispathum in Mexico require a detailed review, being revealed as a complex of several species morphologically similar, but with distinct floral scent composition. Initially, Liebmann (1849) published Hydnostachyon cochlearispathum Liebmann (1849: 24) and H. longirostre Liebm. (1849: 24) , and Schott (1853), transferred them to Spathiphyllum . Engler (1879) published S. cochlearispathum and S. cochlearispathum var. longirostre (Liebm.) Engler (1879: 221) . Spathiphyllum cochlearispathum var. longirostre , a taxon that is currently a synonym of S. cochlearispathum , has similar characteristics to the latter species as referred to by Bunting (1965). However, S. lacustre , also considered a synonym of S. cochlearispathum by Bunting (1965), has characteristics that separate it from S. cochlearispathum , therefore, it is considered a different species (Díaz Jiménez et al. unpubl.).

Spathiphyllum cochlearispathum was formerly considered a species with a wide morphological variation, growing from sea level to 1600 m in different types of vegetation in the south of Mexico, in the states of Chiapas, Oaxaca, Tabasco, Veracruz, and Yucatán ( Croat & Acebey 2015), and the only species reported for Tabasco ( Díaz Jiménez et al. 2015), but our detailed review of herbarium specimens and the collection of specimens from different populations, revealed that none of the studied specimens corresponds to S. cochlearispathum . Therefore, its presence in the state of Tabasco is currently doubtful (Díaz Jiménez et al. unpubl.). So far, the use of floral scent composition has been scarcely used to distinguish botanical species but is becoming more used in recent years to separate species ( Peakall & Whitehead 2014, Chen et al. 2017, Gervasi et al. 2017, Powers et al. 2020), even in sympatric and morphologically similar species ( Okamoto & Su 2021). These new species of Spathiphyllum have different odors, and whether these differences have any impact on their pollinator´s spectrum is still to be determined (see for example Díaz Jiménez et al. 2019). In this sense, at least with scented aroids, we consider it important to, when possible, reinforce species description with ecological data such as the volatile composition of floral scents and pollinators, especially for closely related aroids.

Figures

FIGURE 1. Map showing the collection sites of Spathiphyllum maldonadianum (red dots) and S. wilfridianum (red triangle) in the state of Tabasco. The floral scent of S. maldonadianum was collected in situ in Pomoquita (bottom red dot) and of S. wilfridianum from a cultivated plant in Comalcalco (red star; cultivated individual).

FIGURE 4. Spathiphyllum wilfridianum. A. Cultivated adult plant. B. Adaxial view of the blade. C. Portion of petioles showing entire sheath margins (arrow). D. Inflorescence showing spathe and spadix in anthesis. E. Pistils. Photos by P. Díaz Jiménez.