Prosopanche panguanensis C.Martel & Rob.Fernandez, 2018

Martel, Carlos, Fernandez-Hilario, Robin, Tello, Juan André, Arteaga, Robert G. & Gerlach, Günter, 2018, Prosopanche panguanensis (Aristolochiaceae), a new species from central Peru, Phytotaxa 364 (3), pp. 241-249 : 242-245

Prosopanche panguanensis C.Martel & Rob.Fernandez sp. nov. ( Fig. 1–5 )

Similar to Prosopanche costaricensis L.D. Gómez & Gómez-L., but differing with haustorial rudiments predominantly very short (vs. long haustorial rudiments along), solitary flowers (vs. flowers in fascicles), staminodes cucullate and sessile (vs. bilobed in the apex), a perigonial tube prolonged above the insertion point of the synandrium (vs. perigonial tube not prolonged) and tepals 14.2–26 mm long (vs. 30–44 mm long).

Type:— PERU. Huánuco: Province of Puerto Inca, District of Yuyapichis, Panguana Private Conservation Area, surroundings of the research cabins , 9.616254°S 74.934499°W, 230 m, 25 March 2016, Martel & Tello 85 (holotype USM!) .

Perennial holoparasitic plant, hypogean, achlorophyllous. Rhizomes 3–5-angular, 8.6–15.4 mm diam., fleshy; haustorial rudiments on the angles, wart-like, numerous, 0.6–4.9 mm apart, 0.8–1.6(–4.5) mm long. Stem absent. Leaves absent. Bracts absent. Flowers isolated, bisexual, emergent, hard, tree bark like texture; pedicel 7.4–77 × 9.2–13.3 mm; perigonial tube 4–7 mm long (from the stigma surface to the insertion of the synandrium), 9–24 mm long (from the insertion of the synandrium to connation point of the tepals); tepals valvate, fleshy, 3(–4), outer surface brown, inner surface ochre, 14.2–26 × 11.4–21 mm, linear, ovate to ovate-oblong, apex acuminate; osmophores developed, oriented on the ventral surface of the tepal apices, up to 11 mm thick, spongy and white during the anthesis with vanilla-like scent; synandrium with 3 anthers, each with 8–11 thecae, ovoid to elliptic, trigonous at the apex, ochre the first day, dark-brown the second day, 13.6–22 × 11–14 mm, filaments 2.9–4.1 × 2.6–3.1 mm; staminodes 3, reflexed, sessile, cucullate, fleshy, rugged, thin, 3.8–4.2 × 2.1–2.3 × 1.6–2.1 mm; ovary inferior, 17.1–27.1 × 19.6–22.4 mm, oblong to obovoid; stigma surface tri-radiate, lamellate, 9–11 lamellae per side, each lamella with 4 to more than 20 folds; ovules numerous, embedded in fleshy, parietal placenta. Fruit hypogean, berry-like, ripe placentae fleshy, bright white, embedding numerous seeds; seeds rugulose, black.

Phenology: —The species flowers between January and March.

Distribution, Habitat, and Ecology: — Prosopanche panguanensis is known only from the rain forest of central Peru, departments of Huánuco, Junín and Pasco ( Fig. 4 ). We recorded individuals of P. panguanensis parasitizing roots of Inga ( Fabaceae ). Abarema and Zygia ( Fabaceae ) have also been recorded hosting P. panguanensis ( JBM-Perú 2009). Flowers of P. panguanensis have been observed in Panguana being visited by small Nitidulidae beetles that copulate in the stigmatic chamber and feed on pollen of the anthers. Similar observations have been recorded for other Prosopanche species ( Bruch 1923; Cocucci & Cocucci 1996). Flowers are strongly scented, the floral scent slightly resembles that of commercial vanilla essence.

Additional material examined: — PERU. Junín. Province of Satipo: District of Rio Tambo, Comunidad Nativa Parijaro camino al Parque Nacional Otishi , 11°58’9.9”S 73°40’18.9”W, 1000 m, 26 October 2013, Valenzuela et al. 26751 ( HOXA, photo!; MO, photo!). Pasco. Province of Oxapampa: District of Constitución, Caserío Atahualpa , 09º57’56.48”S 75º01’36.30”W, 230 m, 20 February 2015, Fernandez & Flores 882 ( MOL!) ; Caserío Atahualpa , 09º57’56.48”S 75º01’36.30”W, 230 m, 20 February 2015, Arteaga & Fernandez 164 ( MOL!) ; District of Palcazu, Yanachaga-Chemillén National Park, Paujil Station , 10º19’31”S 75º15’51”W, 380 m, 10 March 2009, Vásquez et al. 35506 ( USM!; HOXA, photo!; MO, photo!) .

Conservation Status:— Prosopanche panguanensis is known from four localities. Although several flowers have been found in each locality, they all probably belong to only few individuals. Nevertheless, plants of Prosopanche are easily overlooked as they are only observable during flowering time and the flower colour resembles the soil colour. Therefore, an assessment of the population size might not be suitable at this moment and according to the IUCN Red List ( IUCN 2017), it can be listed as Data Deficient (DD).

Etymology: —The new species was named after Panguana Private Conservation Area, highlighting that the first records and most of the observations on the plant’s ecology were made there.

Comments: — Prosopanche panguanensis is the only Prosopanche species with sessile cucullate staminodes and a perigonial tube prolonged above the insertion point of the synandrium ( Fig. 1–5 ). This latter character was previously mentioned by Cocucci (1965) as one of the main differences between Prosopanche and Hydnora ; hence, its presence in a Prosopanche species changes this situation. Additionally, P. panguanensis presents bigger relative size of the osmophore than other species of the genus; this character recalls the osmophores [“cucullus” sensu Vaccaneo (1932)] that are observed in some species of the Hydnora genus ( Musselman & Visser 1989; Bolin et al. 2018). While the perigonial tube and the osmophores in P. panguanensis are relatively similar to morphology of Hydnora , the presence of a synandrium, an inner whorl of staminodia and the ovules embedded in the placenta place this new species with Prosopanche ( Meijer 1993) . Although P. paraguanensis presents some characters unique in the genus it seems to be closely related to P. costaricensis , since both share a valvate anthesis and the general morphology of the rhizome and flower ( Table 1 ); nevertheless, P. panguanensis has solitary flowers (versus fascicles in P. costaricensis ), tepals 14.2–26 mm long (vs. 30–44 mm long) and staminodes cucullate (vs. bilobed). Prosopanche panguanensis and P. costaricensis occur in the rainforest, whereas P. americana , P. bonacinai and P. caatingicola grow in predominantly dry-ecosystems (i.e. the Caatinga and Chaco domain). Previous collections of P. panguanensis were first identified as P. americana (i.e. JBM-Perú 2009; Valenzuela et al. 2015), giving the misconception that P. americana also occurs in Peru ( Machado & Queiroz 2012; Vasquez & Rojas 2016). Ulloa Ulloa et al. (2017) did not list any Prosopanche species for Peru, which may have overlooked recent reports (e.g. Valenzuela et al. 2015, Vasquez & Rojas 2016) or considered the Peruvian specimens not consistent with any described Prosopanche species. Indeed, P. panguanensis and P. americana are clearly different in all the characters considered by Cocucci (1965) to be important to differentiate Prosopanche species. To the best of our knowledge, there is no confirmed collection of P. americana for Peru. Prosopanche americana might be restricted to southern South America, specifically to the Chaco domain ( Argentina, Bolivia, Brazil and Paraguay; Cocucci 1965). Although previous authors (e.g. JBM-Perú 2009; Valenzuela et al. 2015) pointed out that the genus was only recently reported for Peru, the first report of any Prosopanche from Peru dates back to Harms (1935), who recorded a collection by Günther Tessmann from the basin of Santiago River in Northern Peru ( Fig. 6 ). Unfortunately, Tessmann’s specimen is unavailable, probably it is destroyed or lost. Like other Prosopanche species, plants of P. panguanensis are parasitizing roots of Fabaceae species, especially Inga , as reported for P. costaricensis ( Gómez & Gómez 1981) .

Figures

FIGURE 1. Prosopanche panguanensis. A. Habit, with details of the emerging flowers and a rhizome section. B. Flower in anthesis with details of the tepals. C. Longitudinal section of a young flower. D. Synandrium, in two views with details of the thecae. E. Staminodes in a cross section of the perigonial tube, view from below. F. Lamellate stigma lamellae in a cross section of the perigonial tube, view from above. Drawing by Delsy Trujillo, based on Martel & Tello 85 (USM!).

FIGURE 2. Prosopanche panguanensis. A. Group of flowers, one in anthesis. B–C. Single flowers in their first-day anthesis, top and lateral view; note the valvate anthesis and tepals fused below two thirds of the synandrium. D. Flower, at second day of anthesis with the tepals manually opened and the pollen released. Photographs by Carlos Martel.

FIGURE 3. Prosopanche panguanensis. A. Cucullate staminodes (St) with rugged surface and fussed filaments (F) of the synandrium, in a cross section of the perigonial tube and view from below. B. Stigma with its irregularly folded lamellae, in a cross section of the perigonial tube and view from above. Photographs by Carlos Martel.

FIGURE 4. Prosopanche panguanensis (A and C) and P. costaricensis (B and D). A–B. View of flowers in anthesis of P. panguanensis, with one tepal manually opened, and P. costaricensis. C–D. View from below of staminodes of P. panguanensis and P. costaricensis. Photographs by Robin Fernandez, based on Fernandez & Flores 882 (MOL!) and Flores 01 (CR!).

FIGURE 5. Prosopanche panguanensis (A and C) and P. costaricensis (B and D). A–B. Perigonial tube from the insertion of the synandrium. C–D. Flower with the perigonial tube, tepals, with a removed tepal, and the synandrium. Photographs by Robin Fernandez, based on Fernandez & Flores 882 (MOL!) and González et al. 8861 (LSCR!).

FIGURE 6. Geographical locations of Prosopanche known from Peru. Prosopanche panguanensis (dot) and Tessmann’s record (star; Harms 1935). Prepared by Carlos Martel.