Aristolochia longissima M.A. Blanco, J.E. Jiménez & 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 : 173-176

Aristolochia longissima M.A. Blanco, J.E. Jiménez & Aguilar , sp. nov. ( Figs. 1 , 2 , 4c )

Type:— COSTA RICA. San José: Turrubares, Reserva Biológica Carara [Parque Nacional Carara], cuenca del Río Grande de Tárcoles, puesto Carara, Río Carara , abajo de la unión con Río del Sur , 100–200 m, 5 Apr. 1993 (fl., fr.), B . E . Hammel & M . Grayum 18951 (holotype: CR!, isotype: MEXU!) .

Similar to Aristolochia belizensis Lundell (1971: 173–174) by its oblong leaf blades, straight to slightly geniculate perianth with an angle of 150−170º between utricle and tube, utricle ellipsoid, and a lanceolate unilobed limb, but differs from that species in its perigone tube straight (vs. slightly curved upward in A. belizensis ), perigone limb narrowly lanceolate, gradually long-attenuated and flagellate toward the apex, 7.3–12 cm long (vs. lanceolate to narrowly ovate, acute at apex, 5.5–6.5 cm long in A. belizensis ), with tightly revolute margins and purple with white spots only proximally, that turns white medially and distally with some purple spots medially (vs. limb with a more loosely revolute margin and white proximally that turns purple medially and distally in A. belizensis ).

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 1–2.3 cm long; blade oblong, 11–15 × 2.5–6.4 cm, concolorous, with conspicuous pellucid gland dots, basally cordate, the sinus 0.2–1 cm deep, apically acuminate, adaxial and abaxial surfaces glabrous to sparsely puberulous with hirsute indument, trinervate. Inflorescences axillary, cymose, with 1–3 sequentially-produced flowers; inflorescence axis 1.2–5.7 cm long; bracts ovate, basifixed, 0.3 × 0.2 cm; pedicel plus ovary 5–6.2 cm long, puberulous. Perigone straight or slightly geniculate with an angle of 150−170º between both utricle and tube and tube and limb, externally with hirsute indument, purple to reddish-green with purple or green-translucent veins, with a citronella-like aroma or unscented; utricle ellipsoid, gibbous, 4.1–8.0 × 1.4–2.4 cm, inner surface white proximally, purple medially and white-purple distally, covered by white trichomes; syrinx equilateral, cylindrical, extending up to 0.5 cm inside the utricle, white; tube cylindric, straight to (rarely) slightly curved, 5–8 cm long, 0.4–0.6 cm in diameter proximally, 0.4–1 cm in diameter distally, inner surface purple covered by white trichomes; fauces rounded, dark purple, with white trichomes; limb unilobed, narrowly lanceolate, gradually long-attenuated and flagellate toward the apex, 7.3–12 × 1–1.3 cm, margins revolute proximally, glabrous to puberulous, purple with small white spots proximally, white medially and distally, held on the upper part of the tube and horizontal to nearly erect in natural position during anthesis. Gynostemium coroniform, 0.7–0.8 × 0.4–0.5 cm, slightly pubescent; stigmatic lobes 6, 0.3 cm long, creamy white; anthers 6, linear-oblong, 0.4 × 0.2 cm. Capsule ellipsoid, 8–11 × 5–5.2 cm (undehisced), apically rounded, with lateral dehiscence and fenestrate septa. Seeds subtrapezoid, 2-winged, 0.9–1 × 1.5–1.7 cm (wings included), brownish.

Distribution and habitat: —Currently known from the wet central and south Pacific regions of Costa Rica, from sea level to 700 m, specifically in Carara National Park, Tinamaste (Pérez Zeledón), Longo Mai (Buenos Aires), Osa Peninsula and Refugio Nacional de Vida Silvestre Golfito ( Fig. 3 ). It occurs in primary and secondary forest, where the vines reach the canopy. Apparently endemic of Costa Rica.

Phenology:— Flowering in the field has been recorded between January and June. Fruits have been collected in January , April, June and October. Flowering occurs throughout the year in greenhouse cultivation in San José, Costa Rica (1100 m), and it is possible that the flowering and the production of fruits occur throughout the year in its natural populations, as in many other species of series Thyrsicae ( Jiménez 2016) .

Conservation status:— Aristolochia longissima is an infrequent species protected in Carara National Park, Longo Mai Reserve, Golfo Dulce Forest Reserve, and Golfito National Wildlife Refuge. Due to its limited occurrence in less than ten locations, occupying an area of less than 2000 km 2, and the agricultural (mostly extensive fields of African oil palm) and urban expansion threatening its natural populations, A. longissima may be considered as Vulnerable according to the IUCN Red List categories and criteria [B2ab(i,ii,iii,iv)] ( IUCN, 2012; IUCN Standards and Petitions Subcommittee 2017).

Etymology: —From the Latin longissimus, “very long”, in reference to the very elongated, nearly straight flowers.

Additional specimens examined: — COSTA RICA. San José: Pérez Zeledón, Tinamaste, Finca de los Suizos, 700 m, 15 Oct. 1997 (fr.), Estrada et al. 1235 ( CR) . Puntarenas: Golfito, Esquinas, margen izquierda de quebrada Nicuesa, 100 m, 6 Apr. 1994 (fl.), G . Herrera & G . Rivera 7021 ( CR, K); Golfito, La Gamba , “bosque de los austriacos”, gap near research plot, 300 m, 3 Apr. 1994 (fl.), W . Huber & A . Weissenhofer 449 ( CR, WU); Golfito, La Gamba, “bosque de los austriacos”, way from La Gamba to Golfito , 70 m, 10 May. 1997 (fl.), W . Huber & A . Weissenhofer 644 ( CR, WU); Golfito, Refugio Nacional de Vida Silvestre Golfito, Río Cañaza , 20 [50] m, 29 Jan. 1995 (sterile), M . Blanco 193 ( USJ); Golfito, Jiménez , La Palma, Guadalupe, camino a la tarde sobre trocha en bosque primario, 123 m, 28 Jun. 2016 (fl., fr.), R . Aguilar 15691 ( USJ [2 parts, 1 part fls. in spirit]); Golfito, distrito Golfito , camino entre Barrio Ureña y La Gamba, 120 m, 20 Jan. 2015 (sterile), M . Blanco 4818 ( USJ); Golfito, distrito Golfito , camino entre Barrio Ureña y La Gamba, 120 m, 20 Jan. 2015 (sterile), M . Blanco 4819 ( USJ); Osa, Rincón, Aguabuena , four-hectare permanent simple plot, 1 Km N of Boscosa Station (Reserva Forestal Golfo Dulce), 350 m, 5 Mar. 1995 (fl.), K . Thomsen 1290 ( CR); Buenos Aires, Volcán, Reserva Longo Mai , bosque primario intervenido al lado del Río Convento , 647 m, 9º15’51.91’’ N, 83º29’39.71’’ W, 17 Jan. 2018 (fl., fr.), J. E . Jiménez & L . D. Arias 4040 ( CR, USJ [2 parts, 1 part fls. in spirit]) . UNITED STATES OF AMERICA. Florida: Sarasota, cultivated at Marie Selby Botanical Gardens , plot L25 , 12 May 1987 (fl.), Walters 2453 ( SEL) .

Comments:— Aristolochia longissima , restricted to lowland rainforest of the Pacific watershed of Costa Rica, can be recognized by its oblong leaves with conspicuous pellucid glands, very long flowers (up to 25 cm) with a limb gradually attenuated along its whole extension, mostly white but with dark purple spots around the fauces ( Figs. 1 , 2 ). Photographs of A. longissima from the same locality, of the specimens Huber & Weissenhofer 449 and Huber & Weissenhofer 644, were first published by Weber et al. (2001: Plate 40, as A. tonduzii ). This species was treated provisionally as “ Aristolochia sp. B ” by Jiménez (2016) and Jiménez & Blanco (2020).

The label data for the specimen Walters 2453 ( SEL) indicate that the plant was in cultivation at the Marie Selby Botanical Gardens in Sarasota , Florida (U.S.A.), without known origin or source, and was vouchered on 12 March 1987; the garden’s plant records indicate that it was removed before 2002 (Karen Norton and Bruce Holst [ SEL], personal communication). At first this may seem like a case of erroneous or mixed-up data, because this species in nature normally flowers high in the canopy. However, we have kept a plant growing in cultivation in a greenhouse at the University of Costa Rica, which has not exceeded 4 meters in height, and has flowered constantly for more than two years .

Aristolochia longissima has been confused with Aristolochia tonduzii O.C. Schmidt (1927: 284) in herbaria, and also in Weber et al. (2001), because of their superficial similarity, but their leaves, and especially their flowers, are different. Aristolochia longissima has glabrous to sparsely puberulous leaves abaxially, a much longer and narrower tube and a longer, attenuated limb, while A. tonduzii has dense hirsute-pilose leaves abaxially, flowers with a shorter and wider tube, and a markedly cucullate limb ( Fig. 4 , Table 1). Also, both species are allopatric; A. longissima is restricted to the wet Pacific lowlands of central and southern Costa Rica, while A. tonduzii is restricted to the Caribbean watershed of southeast Nicaragua, Costa Rica, and Panama.

Aristolochia longissima is also similar to A. belizensis (from Belize, Guatemala, and southern Mexico), but differs from the latter in its limb 7.3–12 cm long, attenuate limb with tightly revolute margins basally, internally white with dark purple spots proximally around the fauces (vs. limb 5.5–6.5 cm long, with loosely revolute margins up to its middle, and with a reverse internal color pattern: white proximally and purple medially and distally). These differences are evident in life ( Fig. 4 , Table 1). González & Pabón-Mora (2017) mentioned that A. belizensis occurs in Costa Rica but without citing any specimens, and we have not recorded this species in the country ( Jiménez 2016, Jiménez & Blanco 2020). See “Notes on the circumscription of some species of Aristolochia series Thyrsicae ” below for more information on A. belizensis .

Aristolochia longissima is also morphologically similar to Aristolochia ornithorhyncha J.E. Jiménez, M.A. Blanco , the other species newly described next. See below for a detailed comparison between both.

Figures

FIGURE 1. Aristolochia longissima. A. Shoot segment with leaves. B. Detail of leaf surface showing pellucid gland dots. C. Flower in lateral view. D. Flower limb, flattened for the most part. E. Flower limb (showing natural conformation in anthesis) and distal part of tube. F. Detail of tube and limb juncture on lateral view, showing revolute margins (limb toward the left). G. Longitudinal section of the utricle. H. Gynostemium in female phase (with the stigmatic surface exposed and anthers closed). I. Gynostemium in male phase (with stigma closed and anthers dehisced). J. Capsule before dehiscence. K. Seeds. Drawings based on live specimen of R. Aguilar 15691 (USJ), with exception of B, I and K, based on live specimen of J.E. Jiménez & L.D. Arias 4040 (USJ).

FIGURE 2. Aristolochia longissima. A. Branches and flower buds (ruler length= 21 cm). B. Detail of leaf surface showing pellucid gland dots. C. Flower, with tube abnormally curved to the side. D. Flower inside view (top) and limb and distal part of tube (bottom). E. Section of utricle showing gynostemium in female phase. F. Capsule before dehiscence. G. Dehiscent capsule. H. Seeds inside the capsule. A, C, D, E and F based on R. Aguilar 15691 (USJ); B, G and H based on J.E. Jiménez & L.D. Arias 4040 (USJ).

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).