Werauhia maculata Espejo-Serna, López-Ferrari, Aguilar-Rodr., Díaz Jim., 2020

Aguilar-Rodríguez, Pedro A., Jiménez, Pedro Díaz, Espejo-Serna, Adolfo, López-Ferrari, Ana Rosa, Hentrich, Heiko, Dötterl, Stefan, Yovel, Yossi & Macswiney-G, M. Cristina, 2020, A new Werauhia (Tillandsioideae, Bromeliaceae) from Mexico with observations about its reproductive biology, Phytotaxa 446 (2), pp. 128-134 : 129-133

Werauhia maculata Espejo-Serna, López-Ferrari, Aguilar-Rodr., Díaz Jim. , spec. nov. ( Fig. 1 )

A species similar to Werauhia pectinata , but differing in its larger tank forming rosette with leaves conspicuously variegated with dark large purple markings on the abaxial surface (vs. some small purple spots), and in the number of flowers in the inflorescence (38–70 vs. 20–40), and in the size of sepals (1.7–2.3 × 1–1.2 vs. 2.2–3 × 1.2–1.4 cm), and petals (3–3.7 × 1.3–1.4 vs. 2.5–2.8 × 0.8–1 cm) and filaments of the stamens (2.2–2.4 vs. 1.2–1.3)

TYPE: MÉXICO, Tabasco, mpio. de Huimanguillo, Cerro de las Flores, Villa de Guadalupe, 17°22’23.57” N, 93°37’42.57” W, 833 m a. s. l., ecotone of tropical montane cloud forest and evergreen tropical forest, rocky wall, May 6, 2018 (fl), P. A. Aguilar-Rodríguez, P. Díaz Jiménez, M. C. MacSwiney G. & Z. Vallado Negroe PA 0015 (holotype: UAMIZ!, isotype: UJAT!) ( Fig. 2 ).

Plant rupiculous, acaulescent, up to 2 m high in flower; rosettes forming a tank, 50–70 cm tall, 50–60 cm diameter. Leaves rosulate, 15 to 30 per rosette, spreading to recurving; sheaths oblong, 15–20 cm long, 9–11 cm wide, adaxially light brown with dark brown base, abaxially conspicuously variegated with dark purple markings distally, both surfaces densely brown punctulate-lepidote; blades narrowly oblong, 45–60 cm long, 6–9 cm wide, inconspicuously brown punctulate-lepidote on both sides, light green, abaxially conspicuously variegated with dark purple markings on the basal portion (the purple markings more notable on juvenile leaves, covering all of the back, while on the adult leaves they cover only the lower third of the blade). Inflorescence terminal, hanging over to nearly horizontal and then ascending at the distal portion, simple, stramineous both in live material and in herbarium specimens; peduncle terete, robust, 70–90 cm long, 8–10 mm diameter, partially covered by the bracts; peduncle bracts vaginiform, 5–10 cm long, acuminate, green with irregularly distributed purple markings, sparsely punctulate-lepidote; spike linearoblong, 55–65 cm long, with densely arranged 38–70 flowers; rachis whitish-green, 6–7 mm diameter; floral bracts coriaceous, stramineous, ovate, 3–4.5 cm long, 2–3 cm wide when extended and flattened, lustrous, margins hyaline and sinuate, acute or obtuse, inconspicuously veined, ecarinate, glabrous on the abaxial surface, inconspicuous and sparsely brown punctulate-lepidote on the adaxial surface, equal to or larger than the internodes. Flowers divaricate, downward secund, zygomorphic, sessile or very slightly pedicellate; sepals free, coriaceous, green with reddish-purple apex, lustrous, ovate, 2–2.3 cm long, 1–1.2 cm wide, inconspicuously veined, ecarinate, margins hyaline, acute, glabrous; petals white to greenish-white, narrowly oblong, the blade spreading to recurving, especially the two lateral ones, 3.7–4 cm long, 1.3–1.4 cm wide, rounded, the two basal appendages 4–10 mm long; stamens subequal, shorter than the petals, all gathered and pressed to the upper petal; filaments white, linear, flat, 2.2–2.4 cm long; anthers yellow, oblong, 7–10 mm long; pollen grains monocolpate, elliptic in shape with an irregular outline, reticulate, heterobrochate; ovary ovoid, 8–10 mm long, style white, linear, 20–28 mm long, exceeding the stamens; stigma light green, much reduced, 1–2 mm in diameter. Capsule ellipsoid, dull brown, 1.6–2 cm long and 6–9 mm diameter. Seeds 3–5 mm long with a coma 2–10 mm long, reddish brown.

Additional specimen examined (paratype):— MEXICO. Tabasco: Municipio Huimanguillo, Cerro de las Flores (Cerro el microondas), Villa de Guadalupe, 17°22’26”N 093°37’51”W, 750 m, 28 April 2009, Pedro Díaz Jiménez, T. Magaña R. & A. M. de la Cruz Lopez 784 (UJAT).

Etymology: The specific epithet ‘maculata’ refers to the conspicuously large dark purple spots on the abaxial surface at the base of the leaves.

Distribution, habitat and phenology: Werauhia maculata is until now only known from the municipality of Huimanguillo in the state of Tabasco, Mexico ( Fig. 3 ); however, it is likely to be present in other adjacent locations of the sates of Chiapas and/or Oaxaca. Plants of the new taxon grow rupicolous on the edge of the talus, exposed to the sun, and forming groups of numerous individuals, and grow together with other bromeliad species such as Pitcairnia recurvata , Pitcairnia imbricata and Werauhia nutans , between 700 and 1000 m a.s.l. elevation. It flowers from April to July.

Biology and floral ecology: The flowers of Werauhia maculata begin anthesis between 17:00 and 18:00 o’clock approximately one and a half hours before nightfall. The species produces one to a maximum of two flowers every one or two days, during its flowering period. Flowering appears to be synchronous in the whole population. Dehiscence of the pollen occurs between 18:00 and 19:00 o´clock when the stigma also becomes receptive. The flower withers at dawn, around 06:30 hrs. We performed hand-pollination treatments in situ (see Aguilar-Rodríguez et al. 2014), and tests of self-pollination resulted in no fruits due to spontaneously self-pollination (i.e., untouched flowers and excluded from pollinators), probably due to the disposition of the anthers (herkogamy). It is a facultative self-compatible species, producing seeds with pollen from the same flower (384 ± 42.44 seeds, n =3 fruits of 3 individuals) or from another flower (388.67 ± 161.81 seeds, n =3 fruits of 3 individuals). The accumulated production of nectar per night ranges from 60 to 100 µl per flower, with a mean sugar concentration of 13 % (13.79 % ± 2.74 %, n =3 flowers of 3 individuals, which is similar to other species within the genus; Krömer et al. 2008). It presents a musky floral aroma, similar to that of other species in the genus Werauhia , which is the most intense between 20:00 and 22:00 o´clock, continuing until the following morning. Analysis of the chemical composition of the aroma has mainly identified Acetoin, Acetoin acetate, (Z)- or (E)-α-Bergamotene, 2,3-Butanediol, Isoamyl acetate, 3- + 2-Methyl-1-butanol, 4-Methyl-3-penten-2- one, and 2- Phenylethanol (P. Díaz Jiménez et al. unpublished data). Considering the characteristics of the nectar, the time of anthesis, and the floral morphology of the new species, as well as the previous reports for the genus ( Aguilar-Rodríguez et al. 2019), it is possible to associate it with a bat-pollinated syndrome.

Comments: According to the infrageneric classification proposed by Grant (1995a), Werauhia maculata belongs to the section Werauhia J. R. Grant. Although it had mistakenly been identified as Werauhia gladioliflora ( Díaz Jiménez et al. 2010) , the new species presents some similarities with W. pectinata ( Smith 1941: 387) Grant (1995a: 33) and W. noctiflorens Krömer et al. (2007: 336) ; however, these three species present clear differences in floral characteristics and ecology ( Table 1). Its distribution, probably restricted, makes this a species vulnerable to the threat of habitat loss.

Figures

FIGURE 1. Adult individual of Werauhia maculata at the type locality.A. Flowering plant; B. Detail of the tank rosettes of a grown plant; C. Frontal view of the flower in anthesis; D. Lateral view of the flower; E. Ecuatorial view of a pollen grain; F. Lateral view of the pollen grain, showing the aperture an ornamentation; G. Fruit; H. Juvenile individual. Photos: A and B: Zuemy Vallado; C, D and G: Roberto Castro; E and F: Heiko Hentrich; H: Pedro Díaz Jiménez.

FIGURE 2. Werauhia maculata. A—Habit. B—Flower. C—Floral bract. D—Sepals. E—Petals. F—Anther. G—Detail of the stigma. Based on a cultivated individual. Drawings by Zuemy Vallado Negroe.

FIGURE 3. Type locality and known distribution of Werauhia maculata in Tabasco, Mexico.