Problematic specimens turn out to be two undescribed species of Bignonia (Bignoniaceae)

Abstract Bignonia comprises 29 species of lianas characterized by eight phloem wedges, leaves usually 2-foliolate, mostly simple tendrils and opaque seed wings. The analysis of herbarium specimens in preparation for a taxonomic revision of the genus led to the recognition of two new species: (i) Bignonia cararensis from Costa Rica, characterized by a thyrse with lateral compound dichasia and lack of interpetiolar ridge, and (ii) Bignonia sanctae-crucis from Bolivia and Brazil, distinguishable by its membranous leaflets, membranous calyx and small fruits. We provide detailed descriptions, illustrations, distribution maps, initial conservation status assessments, and comparisons of the newly described taxa with closely related species.


Introduction
Bignonia L. is the fi fth largest genus in the Neotropical tribe Bignonieae (Bignoniaceae), with 29 species distributed from Argentina to USA (Zuntini et al. 2015). Th e genus comprises lianas with eight phloem wedges, leaves usually 2-foliolate, prophylls of the axillary buds foliaceous and bromeliad-like (small, decussate, triangular prophylls resembling a bromeliad), mostly simple tendrils and opaque seed wings (Loh mann and Taylor 2014). Additionally, these plants have showy rather large fl owers, pink corollas, and septicidal capsules that contain numerous seeds, usually winged. Molecular studies have found that Bignonia is a highly supported clade that combines previously recognized genera, such as Clytostoma Miers ex Bureau and Cydista Miers (Lohmann 2006). Th e species of these two former genera share a variety of morphological features, such as variously cylindrical or quadrangular stems, a cupular calyx, dorso-ventrally fl attened corollas, and a reduced nectariferous disk, which made their generic identifi cation sometimes diffi cult. While preparing a monograph of Bignonia (Zuntini, Taylor and Lohmann, in prep.), more than 4,000 collections were analyzed and several problematic specimens that had been previously identifi ed in a variety of Bignonieae genera were found to belong to Bignonia. However before these materials were fi nally identifi ed to genus, the identity of these specimens was so unclear that they were confused with four diff erent genera, and the fl owering and fruiting specimens of each of these new species were considered to belong to diff erent genera. Once identifi ed as Bignonia, it became clear that these specimens represent two undescribed species.
Th ese two new species are Bignonia cararensis Zuntini from Costa Rica and Bignonia sanctae-crucis Zuntini from Bolivia and western Brazil. Within Bignonia, these new species are not very similar and are not closely related to each other, however, these species are each similar to previously described species.
With these two new species, Bignonia is now composed of 31 species, with no morphological or geographical changes in the circumscription of the genus. Our results highlight the importance of large diverse herbarium collections for understanding the systematics of tropical plants, and also of broadly surveying all the specimens of a group before fi nalizing monographic studies rather than studying only a selected set of specimens of a given genus.

Methods
Specimens from the following herbaria were examined: CR, F, INB, MO, NY, SPF, USJ (acronyms following Th iers 2015). Th e morphology descriptions follow mainly Lohmann and Taylor (2014), with additional terminology from Leaf Architecture Working Group (1999), Radford et al. (1974) and Weberling (1989). For indumentum, we follow Nogueira et al. (2013) with each trichome type described separately; peltate glandular trichomes are described according to their density as sparsely, moderately or densely lepidote, and patelliform glandular trichomes are presented here as "glands." In the descriptions, terms inside parentheses denote rare conditions. Th e conservation status assessments follow IUCN guidelines (IUCN 2012), with the evaluation of geographic range based on the extent of occurrence (EOO). Distribution maps were prepared using the specimen database that was compiled as part of an ongoing monographic study of the whole genus (Zuntini, Taylor and Lohmann, in prep).  Figure 1.
Diagnosis. Th is new species is closely related to Bignonia uleana (Kraenzl.) L.G.Lohmann, but diff ers by the absence of interpetiolar ridges, infl orescences with compound dichasia (vs. simple dichasia in B. uleana) and fruits up to 14 cm long with cylindrical and delicate spines (vs. longer than 16 cm with triangular and rough spines in B. uleana). Table 1.
Distribution. Th is species is known only from Parque Nacional Carara, in Puntarenas, Costa Rica, between 20 and 100 m elevation (Fig. 2).
Phenology. Th ree fertile collections are documented for Bignonia cararensis: a single fl owering specimen was collected in February and two fruiting specimens were collected in February and October.
Etymology. Th e name is a reference to the type locality. Conservation status. Th e collections from the main herbaria of Costa Rica (CR, INB and USJ) were consulted, but so far this species is only documented from Parque Nacional Carara. Since B. cararensis is known exclusively from the type locality, its full distribution cannot be accurately assessed and is here listed as Data Defi cient (DD). Additional fi eldwork is necessary to estimate the number of mature individuals and to assess the full extend of the species' distribution.
Discussion. Th is species is similar to B. uleana, a species from Bolivia, central western Brazil and Peru. Bignonia cararensis can be recognized by the absence of interpetiolar ridges (vs. present in B. uleana), the infl orescences in lateral compound dichasia (vs. lateral simple dichasia in B. uleana), and the fruit up to 14 cm and with cylindrical delicate spines (vs. longer than 16 cm with triangular rough spines in B. uleana) (Table 1).
Th  Clytostoma pterocalyx and Cydista lilacina were reported as new records for Costa Rica (Burger and Gentry 2000, Hauk 1997, Jiménez and Grayum 2002 based on the specimens studied here, but with the re-identifi cation of these specimens both of these species are now known only from South America. Bignonia pterocalyx is found in Venezuela and Colombia, and B. lilacina is distributed throughout Amazonia. Th e Carara National Park is located in the northern portion of the Tárcoles-Térraba fl oristic region, which extends through the central portion of Pacifi c coastal Costa Rica (Hammel et al. 2004). Th is region has a combination of dry and moist forests, and includes elements from Nicoya and Osa Peninsulas, where B. cararensis might also be found.
Distribution. Th is species is found in evergreen or semideciduous forests in Western Amazonia, occurring in Bolivia (Beni, La Paz and Santa Cruz) and Brazil (Acre, Amazonas and Mato Grosso), between 160 to 700 m alt. (Fig. 4).
Phenology. Th is species was collected with fl owers in June, September, October and November. A single fruiting specimen was collected in July.
Conservation status. Bignonia sanctae-crucis is known from only seven locations but is considered Least Concern (LC) given its wide extent of occurrence (over 600.000 km 2 ) and the diff erent physiognomies where it occurs, including secondary formations. Th e number of locations where this species is known to occur is likely underestimated because Bignonia species are usually not densely distributed and because this entire region is not well documented fl oristically. Additional fi eldwork is needed in order to fully document the extent of distribution of this species.
Etymology. Th e epithet refers to the type locality, the Department of Santa Cruz (Bolivia), where most specimens were collected.

Discussion.
Bignonia sanctae-crucis and B. potosina share quadrangular and ribbed (winged) stems, prominent interpetiolar ridges, falcate and caducous prophylls, and few-fl owered racemes. Apart from being morphologically similar, these species are also closely related and can be confused. However, Bignonia sanctae-crucis can be distinguished from B. potosina by the membranous calyx (vs. chartaceous in B. potosina) and fruits shorter than 6.8 cm long (vs. fruits longer than 15 cm in B. potosina) ( Table 2). Th ese two species are also geographically widely separated, with B. sanctae-crucis found in Bolivia and central to western Brazil while B. potosina is widely found in Mexico and Central America but not in South America. Bignonia sanctae-crucis can also be confused with the sympatric species B. decora (S.Moore) L.G.Lohmann due to the quadrangular stems shared by both species. However, B. sanctae-crucis can be recognized by its falcate and caducous prophylls (vs. foliaceous and persistent in B. decora), few-fl owered racemes (vs. multi-fl owered thyrses in B. decora) and fruit without ridges (vs. three longitudinal ridges in B. decora) ( Table 2). Quadrangular stems are also characteristic of B. sciuripabulum (Bureau & K.Schum.) L.G.Lohmann, a distantly related species (Zuntini and Lohmann, in prep.) that has a verrucose and glabrous ovary (vs. smooth and lepidote in B. sanctae-crucis) and echinate fruits (vs. smooth in B. sanctaecrucis); B. sciuripabulum is found in Amazonia and the Atlantic forest of Brazil.
Th e only fruiting material of this new species (Nee 52361) was previously identifi ed as Cydista cf. decora (S.Moore) A.H.Gentry [≡ B. decora] (in sched. at NY), a closely related species. Th e fl owering specimens of B. sanctae-crucis, however, were identifi ed as Clytostoma sciuripabulum Bureau & K.Schum. [≡ B. sciuripabulum], Clytostoma uleanum Kraenzl. [≡ Bignonia uleana], and some other Clytostoma species (in sched. at MO and NY). Th e thin-textured corolla probably confused the generic identifi cation, given that most Cydista, as previously circumscribed, were characterized by thicker corollas whereas such thin corollas were characteristic of the previously recognized Clytostoma. Despite its corolla texture, B. sanctae-crucis is not closely related to the species that were included in Clytostoma, and does not have the verrucose glabrous ovary that is characteristic of that group.