Syngonium huastecorum Díaz Jim., Pérez-Farr. & Croat, 2025

Jiménez, Pedro Díaz, Pérez-Farrera, Miguel Ángel, Croat, Thomas B., Salinas-Rodríguez, María Magdalena, Hentrich, Heiko & Aguilar-Rodríguez, Pedro A., 2025, Syngonium huastecorum (Araceae), a new species from the north-central region of Mexico, Phytotaxa 694 (3), pp. 289-294 : 290-294

Syngonium huastecorum Díaz Jim., Pérez-Farr. & Croat , sp. nov. ( Figs. 1 , 2 )

Syngonium huastecorum is morphologically similar to S. podophyllum , but differs from that species in having longer petioles (up to 69.5 cm), medium leaflets with more primary lateral veins per side (9–17 vs. 3–7), fewer inflorescences per axil (1–4 vs. 4–11), inflorescences with longer peduncles at anthesis (up to 13.5 vs. fewer than 10 cm), and staminate flowers lacking a line of fusion between the staminodia (vs. with a distinct line of fusion).

Type:— MEXICO. San Luis Potosí: Municipio Tamazunchale, Tacial, 21°15’17”N, 098°48’48”W, 186 m, 31 Jul. 2021, Pedro Díaz Jiménez, M. Á. Pérez-Farrera & M. M. Salinas-Rodríguez 1598 (holotype HEM 46906!, isotype CHIP).

Appressed-climber or hemiepiphyte at 5 m. JUVENILE LEAVES oblong-sagittate, 19–24 cm long, 11–17 cm wide, posterior lobes oblong to ± triangular, 6.5–10.0 cm long, 4.0– 7.5 cm wide, rounded at apex. ADULT PLANTS with internodes 4–10 cm, 8.0–16.0 mm diam., dark green or dark olive-green, glossy, glaucous, flattened-ribbed on one side, sap milky; roots greenish and brown, up to 4.3 mm in diam. LEAVES erect-spreading, petioles 30.5–69.5 cm, 4–7 mm diam., sheathed 1/2–2/3 its length, sheath erect or extended and with a rounded, and slightly free-ending at apex, rarely with a free tip up to 3.8 cm long, with a free portion to 15–20.5 cm from base of blade, terete, obtusely angular adaxially, glaucous, light green, drying dark and light brown; blades trisect or 5-pedatisect, 19.5–35.0 cm long, 21.5–53.0 cm wide, thin, dark green and semiglossy above, light green and semiglossy below, drying dark yellowbrown to greenish above, light brown and greenish below; medial lobe oblong-elliptic, 19.0– 34.5 cm long, 8–15 cm wide, up to 2.5 times longer than wide, inequilateral, one side up to 10 mm wider, acute or mucronate at apex, cuneate at base; inner lateral lobes 18–30 cm long, 8.5–11.0 cm wide, only slightly shorter than medial lobes, acute at apex, markedly inequilateral, outer margin, 0.3–3.5 cm wider than inner margin; outermost pair of lobes auriculate at base of outer margin, auricles sometimes becoming free, 7.0– 12.2 cm long, 3.0– 4.7 cm wide; primary lateral veins sunken above, 9–17 pairs on median segment, whitish below, dark green above, departing midrib at 40–55° angle, drying dark or light brown above and below; tertiary veins fine, slightly visible but not raised below; midrib rounded and light green below, drying brown above and below. INFLORESCENCES 1–4 per axil, erect at anthesis; prophylls 15–31 cm long, 2-ribbed, light green, drying light brown; peduncle 10–14 cm long, 5.0– 11.5 mm diam., subterete or ± flattened, light green to grayish and glaucous, drying grayish; spathe 9.7–10.8 cm long; tube 2.5–3.3 cm long, 1.3–1.8 cm diam., light green and glaucous outside, light green and whitish within, drying dark brown, blade 7.0– 9.6 cm long, 5.3–5.8 cm wide, light yellowish outside, whitish within, drying light brown, acuminate or cuspidate at apex, sometimes reflexed at apex, deciduous at post-anthesis; spadix 6.8–8.4 cm long; staminate spadix 3.9–5.2 cm long, 11.0– 11.3 mm diam. in middle, white to cream, drying creamy brown, staminate flowers truncate at the apex, 1.1–1.9 mm long, 1.0– 2.1 mm diam., with not line of fusion; sterile staminate portion 1.0– 1.3 cm long, 5.0– 5.5 mm diam.; pistillate portion 2.0– 2.2 cm long, 6.0– 7.3 mm diam., light green, drying dark brown, pistillate flowers, 2.1–3.0 mm long, 2.0– 2.5 mm diam., the stigma discoid., ca. 0.5 mm diam., transparent and glossy. INFRUCTESCENCES immature erect, mature pendent; peduncles 11.5–14.0 cm, light green, dark to yellowish; spathe blade deciduous on immature fruits; syncarp ovoid to ± globose, 5.5–6.5 cm, 3.3–3.5 cm diam., red and glossy when maturity; seeds gray, 5.0– 8.2 mm long, 4.5–5.5 mm diam., ± ovoid.

Distribution, habitat and phenology: — Syngonium huastecorum is endemic to the municipality of Tamazunchale, which is located in the region known as Huasteca Potosina ( Fig. 3 ). It grows in an evergreen sub-deciduous forest at 186 m above sea level. Specimens with inflorescences and infructescences in situ were collected in July, and cultivated plants flowered in September and October.

Eponymy: —This species is named for the Huasteca region of the state of San Luis Potosí, where it was collected. The region owes its name to the biocultural zone that covers parts of the states of Tamaulipas, San Luis Potosí, Veracruz, Querétaro, Hidalgo, and Puebla, and that has similar cultural traits such as music, food, and festivities (Oliver 2008).

Notes: — Syngonium huastecorum represents the tenth species of the genus and eighth within the section Syngonium for Mexico, as well as the fourth species for the state of San Luis Potosí ( Croat 1981, Croat et al. 2019, Croat 2023). This new species is characterized by its long internodes, long petioles, trisect or 5-pedatisect blades, 9–17 pairs of primary lateral veins on the median segment, up to 4 inflorescences per axil, long peduncles, blade of the spathe deciduous at post-anthesis, staminate flowers truncate at the apex and lacking a line of fusion between the staminodia, immature infructescences erect, and pendent at maturity, and syncarps are red and glossy when maturity. It is morphologically similar to S. podophyllum , but that species has shorter petioles, medium leaflet with fewer than twice as many primary lateral veins per side, almost up to three times more inflorescences per axil, inflorescences with shorter peduncles at anthesis, and staminate flowers with visible lines of fusion ( Croat 1981, Croat & Acebey 2015, Croat 2023). It can also be confused with S. neglectum , an endemic species to Mexico that is distributed in the same area, but this species differs in having the tube of spathe almost twice as long and almost three times as wide at anthesis, glossy green externally, red or purple to violet internally. Furthermore, the blade of the spathe is persistent in fruit ( Croat 1981, Croat & Acebey 2015, Croat 2023).

It is possible that the specimen ( Sergio Zamudio R. 7798, MO) collected in the state of Querétaro and determined as Syngonium podophyllum corresponds to S. huastecorum . In that collection, the oblong-elliptic medial lobe has more than 9 primary lateral veins per side and up to three inflorescences per axil. However, it will be necessary to analyze the inflorescences in anthesis in detail to confirm if they belong to the same taxa.

Additional specimens examined (paratypes): — MEXICO. Municipio Comalcalco (cultivated), R /a. Independencia 2da Sección, 18°17′26″N, 93°09′30″W, 8 m, 14 Sep 2024, Pedro Díaz Jiménez 1598b ( HEM!).

Figures

FIGURE 1. Syngonium huastecorum. A. Adaxial view of the leaf blade and petiole; B. Stem showing roots, internodes and partial portion of petioles; C. Inflorescence in anthesis showing spathe and long peduncle; D. Partial portion of the spadix showing staminate flowers, truncate at the apex and with no line of fusion; E. Mature infructescences; F. Seeds. Photos by P. Díaz Jiménez.

FIGURE 2. Syngonium huastecorum. A—Juvenile leaves. B—Adult plant. C—Leaf blade and petiole. D—Inflorescence showing pistillate, sterile, and staminate portion. E—Infructescences. F—Seeds. Based on a cultivated individual. Drawings by Katherine Medina Santiago.

FIGURE 3. Map showing the collection site (black star) of Syngonium huastecorum in the region of Huasteca Potosina, San Luis Potosí, Mexico.