Aristolochia ornithorhyncha J.E. Jiménez, M.A. Blanco & Aguilar, 2021

Jiménez, José Esteban, Fernández, Reinaldo Aguilar & Blanco, Mario A., 2021, Two new species of Aristolochia series Thyrsicae (Aristolochiaceae) from southern Central America, with comments on morphologically similar species, Phytotaxa 520 (2), pp. 169-183 : 176-181

Aristolochia ornithorhyncha J.E. Jiménez, M.A. Blanco & Aguilar , sp. nov. ( Figs. 5 , 6 , 4d ).

Type:— COSTA RICA. Puntarenas, Golfito, Jiménez , bosque primario, 8º29’43.79’’ N, 83º18’46.84’’ W 75 m, 4 Feb. 2016 (fl., fr.), J . E . Jiménez & R . Aguilar 3500 (holotype: USJ [3 parts, including fls. in spirit]; isotype: CR) .

Similar to Aristolochia longissima M.A. Blanco, J.E. Jiménez & Aguilar by its oblong leaves with abundant pellucid gland dots, rectilinear or slightly geniculate perianth with an angle of 150−170º between utricle and tube, utricle ellipsoid, tube cylindric and a perigone limb narrowly lanceolate, but differs from that species by its shorter tube (3.5–4 cm vs. 5–8 cm long in A. longissima ), limb 5–6 cm long with flat margins and green-yellowish spotted brownish purple throughout its extension (vs. 7.3–12.0 cm long, with tightly revolute margins and purple with white spots proximally, white medially and distally in A. longissima ).

Liana, stems with corky bark when mature; young stems puberulous to pubescent with hirsute indument; prophylls not atrophied (pseudostipules absent). Leaves deciduous (with an abscission layer at base of petiole), simple, alternate, distichous; petiole 1.5–2 cm long; blade oblong, 8.1–14.9 × 2.8–4.5 cm, concolorous, with conspicuous pellucid gland dots, basally truncate or subcordate, the sinus 0–0.4 cm deep, apically acuminate, adaxial and abaxial surfaces glabrous to sparsely puberulous with hirsute indument, trinervate. Inflorescence axillary, cymose, with 1–3 sequentiallyproduced flowers; inflorescence axis 1–6 cm long; bracts ovate, basifixed, 0.3 × 0.2 cm; pedicel plus ovary 4.2–6 cm long, puberulous. Perigone straight or slightly geniculate, with an angle of 150–170º between utricle and tube and 70– 90º between tube and limb, externally with hirsute indument, green to creamy-green with green-translucent veins, with a citronella-like aroma or unscented; utricle ellipsoid, gibbous, 4.2–5 × 1.5–1.7 cm, inner surface white proximally, reddish medially and creamy with red spots distally, covered by white trichomes; syrinx equilateral, cylindrical, extending up to 0.4 cm inside the utricle, white; tube cylindric, straight or slightly curved, 3.5–4 cm long, 0.4–0.6 cm in diameter proximally, 0.6–. 8 cm in diameter distally, inner surface creamy covered by white trichomes; fauces rounded, creamy, with white trichomes; limb unilobed, lanceolate, attenuated, caudate and recurved toward the apex, 5–6 × 1.3–1.6 cm, margins revolute proximally, proximally yellowish white with purple-brownish spots, medially and distally greenish-yellow with purple-brownish spots, held on the upper part of the tube and suberect to erect in natural position during anthesis. Gynostemium coroniform, 0.7–0.9 × 0.4–0.5 cm, slightly pubescent; stigmatic lobes 6, 0.4 cm long, creamy-white; anthers 6, linear-oblong, 0.4 × 0.2 cm. Capsules ellipsoid, 8–8.6 × 4.8–5.5 cm, apically rounded, with lateral dehiscence and fenestrated septa. Seeds subtrapezoid, 2-winged, 0.9–1 × 1.5–1.8 cm (wings included), brownish.

Distribution and habitat:— Currently known from the eastern part of the Osa Peninsula in Costa Rica, and Chiriquí province (including the Burica Peninsula) in Panama ( Fig. 3 ), from sea level to 670 m. It occurs in lowland moist forest, in primary and secondary vegetation, where the vines reach the canopy.

Phenology: —Flowering in the field has been recorded in February, April and November. Fruits have been collected in February and November. It is possible that the flowering and the production of fruits occur throughout the year, as in many other species of series Thyrsicae ( Jiménez 2016) .

Conservation status:— Aristolochia ornithorhyncha is a rare species known from few populations and few herbarium specimens. It is only protected in the Osa National Wildlife Refuge (Osa Conservation, Piro). Due to its limited occurrence in less than five locations, occupying an area of less than 500 km 2, and the agricultural and urban expansion threatening its natural populations, A. ornithorhyncha may be considered as Endangered according to the IUCN Red List categories and criteria [B2ab(i,ii,iii,iv, v)c] ( IUCN, 2012; IUCN Standards and Petitions Subcommittee, 2017).

Etymology:— From the Greek ορνιθόρυγχος (ornithorhynkhos), meaning “bird snout” or “bird beak”, in reference to the similarity of the floral limb with the beak of a bird when seen sideways.

Additional specimens examined:— COSTA RICA. Puntarenas: Golfito, Jiménez, Finca Playa Kare Oeste , 8º24’40’’ N, 83º17’00’’ W, 20 m, 13 Nov. 2015 (fl., fr.), R. Aguilar 15430 ( CR, USJ [fls. in spirit]); Golfito, Jiménez, Conservación Osa, Piro, 110 m, 10 Feb. 2016 (fl.), J. E. Jiménez & M. López 3503 ( USJ [in spirit]) . PANAMA.

Chiriquí: Quebrada Tuco, 9 mi south of Puerto Armuelles , 0-150 m, 21 Feb. 1973 (fr.), R. L . Liesner 157 ( MO); Bugaba, La Estrella , carretera a Santa Risa , orilla del Río Escarrea , 270 m, 22 Abr. 2012 (fl.), Martínez et al. 1727 ( UCH [2 parts]); Londres de Gualaca , a orillas del Río Gualaca , 670 m, without specific date [1998, year of determination] (fl.), J . Polanco 2792 ( PMA) ; Chiriquí, Boquete, bosque cercano al Río Cochea, cercano al puente sobre el río que divide Boquete de Dolega , 8º36’22.9’’ N, 82º25’24.8’’ W, 340 m 19 Mar. 2021 (fr.), J. E . Jiménez et al. 5587 ( PMA) .

Comments:— Aristolochia ornithorhyncha is quite similar to A. longissima ; both species share similar leaf, fruit and seed morphology, and can potentially be confused in dry herbarium material without flowers. Populations of both species occur relatively close to each other in the Osa Peninsula, separated by ca. 40 km from each other, and they appear to be allopatric. However, we cannot rule out the possibility that both species occur in sympatry somewhere in the peninsula. Based on the available specimens and our field observations, Aristolochia ornithorhyncha grows in areas with lower average rainfall compared to those where A. longissima occurs. Aristolochia ornithorhyncha was provisionally treated as “ Aristolochia sp. C ” by Jiménez (2016) and Jiménez & Blanco (2020).

Both Aristolochia ornithorhyncha and A. longissima share a citronella-like aroma in its flowers.

Aristolochia ornithorhyncha has been confused with the allopatric A. chapmaniana in herbaria because of their similar leaf, fruit and seed morphology, but differs from that species by its flowers greenish to green-creamy externally (vs. brown-reddish externally in A. chapmaniana ), perigone limb 5–6 cm long, attenuated, internally yellowish white with purple-brownish spots proximally, greenish-yellow covered with purple-brownish spots medially and distally (vs. 6.7–8.5 cm long, oblanceolate and internally creamy yellow proximally and medially, and attenuated, sharply bent backward and heavily spotted with dark maroon distally in A. chapmaniana ; Fig. 4 , Table 1). Aristolochia ornithorhyncha is known only from Puntarenas province in Costa Rica and Chiriquí province in Panama, while A. chapmaniana is known only from Panama province (the type locality is on Barro Colorado Island). González & Pabón-Mora (2017, 2018) stated that A. chapmaniana is also distributed in Colombia and Ecuador, but we have not seen specimens of this species from those other countries. See “Notes on the circumscription of some species of Aristolochia series Thyrsicae ” below for more information on A. chapmaniana .

The flowers of Aristolochia fragrantissima Ruiz (1805: 46–52 , sensu González 1994, González & Pabón-Mora 2017), a western Amazonian species of series Thyrsicae , are similar to those of A. ornithorhyncha , but differ by their markedly geniculate perigonium (forming an angle of ca. 90º between utricle and tube), syrinx aequilateral, shorter tube (2.0–2.5[4.0] cm), and wider, ovate to broadly ovate non-caudate limb without revolute margins. The leaves of A. ornithorhyncha are oblong and with pellucid gland dots, while those of A. fragrantissima are ovate to rarely oblong, markedly cordate (sinus 3–5 cm deep) and (apparently) without pellucid gland dots.

Aristolochia mathewsii Duchartre (1864: 497) , originally published as Aristolochia reticulata Seeman (1854: 193 , nom. illeg., non Aristolochia reticulata Nuttall 1837 [1835]: 162), was described from two collections (syntypes): “David, province of Veraguas ” (currently province of Chiriquí, Panama; without specifying a collection, but obviously Seemann 1242, BM!, K!, cited by González & Pabón-Mora 2018 as Seeman s.n.) and “Tarapoto, Peru (Mathews)” [Mathews 1302, K!]. Seeman´s collection is vegetatively very similar to A. ornithorhyncha , but due to the absence of flowers, it is uncertain if it corresponds to A. ornithorhyncha , A. chapmaniana , A. longissima , or even a different species. Mathews´s specimen is similar to A. fragrantissima but it also lacks reproductive structures.

Although there is a recent taxonomic revision of Aristolochiaceae for Panama ( González & Pabón-Mora 2018), the authors apparently did not see any of the Panamanian specimens listed here under Aristolochia ornithorhyncha .

Together with Aristolochia belizensis (J. Monzón Sierra, personal communication), A. longissima and A. ornithorhyncha are the only three species in the family Aristolochiaceae that are known to have pellucid gland dots, which are evident both in living and dry material under low magnification. Evans (2009) mentions that “oil-secreting cells occur throughout the family, often forming transparent dots on the leaves”; nevertheless, no species are cited as examples, nor if the pellucid dots are visible to the naked eye. More significantly, the presence of such evident pellucid dots in the family is not mentioned in the taxonomical literature. According to our observations, pellucid gland dots are absent in A. chapmaniana , A. constricta Grisebach (1857: 225 ; sensu Jiménez 2016 and Jiménez & Blanco 2020), A. maxima Jacquin (1760: 30) and A. tonduzii (we still have to study material of other species in series Thyrsicae to determine their presence or absence).

Notes on the circumscription of some species of Aristolochia series Thyrsicae : —Some comments are provided here on the circumscription of some species of Aristolochia series Thyrsicae , mainly from Central America.

Aristolochia belizensis was synonymized under Aristolochia ovalifolia Duchartre (1854: 50–51) by Barringer (1983b, 2015; followed by Ortega-Ortiz and Ortega-Ortiz 1997), while both were recognized as separate species by González and Pabón-Mora (2017). The leaf blades of A. belizensis are markedly oblong, typically 2−3 times as long as broad, cordate, and light yellowish-brown when dry. In contrast, those of A. ovalifolia are oval to oblong, 1.5−2 times as long as broad, the margin very slightly depressed at the junction with the petiole (not forming a sinus), and dark olive green to black when dry. The flower limb of A. belizensis is apically acuminate, its lateral margins are revolute only along the proximal third, and its inner surface is white proximally and purple both medially and distally. In contrast, the flower limb of A. ovalifolia is apically subtruncate, its lateral margins are revolute along most of their extension, and its inner surface is covered with purple warts.

The leaf and flower illustrated by Pfeifer (1966) as A. ovalifolia actually corresponds to those of A. belizensis . The drawing of the open flower appears to be a composite reconstruction from both species; the calyx tube in A. belizensis is never as strongly curved as in the drawing, but it is often so in A. ovalifolia , while the bud drawing fits better that of A. ovalifolia . This probably led Barringer (1983b) to synonymize A. belizensis with A. ovalifolia . When Lundell (1971) described A. belizensis , only fruiting specimens were available to him. Photographs of flowers in anthesis of both species are presented here for comparison ( Fig. 4 ). Lundell (1971) correctly pointed out that A. belizensis is the species referred to as A. chapmaniana Standley (1933: 60 , t. 9) in Standley and Record (1936) and in Standley and Steyermark (1946). Standley and Record (1936) cite the specimen Schipp S-415 (BRH, F, S, from Belize) as a voucher for A. chapmaniana . Pfeifer (1966) mentions sterile specimens resembling A. chapmaniana from British Honduras ( Belize), but in 1959 he annotated Schipp S-415 (F), which has a nice flower, as A. chapmaniana . This specimen, which is actually of A. belizensis , was apparently never seen by Lundell. Balick et al. (2000) also listed A. chapmaniana for the flora of Belize, based on a misidentified specimen of A. belizensis .

Our circumscription of A. chapmaniana differs from that of González and Pabón-Mora (2017). Under this name, those authors included plants from Colombia and Ecuador with a leaf shape and floral limb conformation different than those of plants from the type locality in Panama (e.g., González 542, COL, from Medellín, Colombia, illustrated in detail by González 1990: Fig. 20 as A. tonduzii ) that in our opinion are more similar to Aristolochia schmidtiana Hoehne (1942: 90–91 , tab. 93). In our more restricted circumscription, A. chapmaniana is characterized by short-petiolate, essentially glabrous (when mature), oblong to spathulate, elongate leaves (2.5–5.5 times as long as broad,) with a small but well-defined teardrop-shaped sinus; the floral limb is mostly yellowish within and slightly but consistently bent backward and heavily spotted with dark maroon on the distal third ( Fig. 4 , Table 1), and is endemic to Panama.

Figures

FIGURE 3. Geographic distributions of Aristolochia longissima and A. ornithorhyncha in Costa Rica and Panama, based on herbarium specimens.

FIGURE 4. Photographs of living flowers of the larger-flowered species of Aristolochia series Thyrsicae in Central America, for comparison. A. Aristolochia belizensis (unvouchered; from Belize, photo by Jan Meerman). B. Aristolochia chapmaniana (T. Croat 6733, MO; from Panama, photo by T. Croat). B1. Aristolochia chapmaniana (unvouchered; from Panama, courtesy of STRI research portal). C. Aristolochia longissima (R. Aguilar 15691, USJ; from Costa Rica, photo by R. Aguilar). D. Aristolochia ornithorhyncha (J.E. Jiménez & A. Aguilar 3500, USJ; from Costa Rica, photo by J.E. Jiménez). E. Aristolochia ovalifolia (N. Morales 25, UJAT; from Tabasco, Mexico, photo by Neil Morales). F. Aristolochia tonduzii (J.E. Jiménez et al. 3444, USJ; from Costa Rica, photo by J.E. Jiménez).

FIGURE 5. Aristolochia ornithorhyncha. A. Shoot segment with leaves and flower buds. B. Detail of leaf surface showing pellucid gland dots. C. Flower in lateral view. D. & E. Limb in frontal view. F. Longitudinal section of the utricle.G. Gynostemium in female phase (with the stigmatic surface exposed and anthers closed). H. Gynostemium in male phase (with stigmatic suface closed and anthers dehisced). I. Seeds. J. Capsule before dehiscence. Drawings based on live specimen of R. Aguilar 15430 (USJ), except for B, H and I, based on the live specimen of J.E. Jiménez & A. Aguilar 3500 (USJ).

FIGURE 6. Aristolochia ornithorhyncha. A. Branches showing upper surface of leaves. B. Branch with developing fruits, showing lower surface of leaves. C. Detail of leaf surface, showing pellucid gland dots. D. Limb in frontal view. E. Dissected utricle, showing the internal pigmentation and the cylindrical syrinx. F. Post-anthesis flowers, fallen on the forest floor. G. Capsule before dehiscence. H. Dehiscent capsules. I. Seeds.A, B, D and E based on R. Aguilar 15430 (USJ); C, F, G, H, and I based on J.E. Jiménez & A. Aguilar 3500 (USJ).