Pinguicula rosmarieae Casper, Bussmann & T.Henning (Lentibulariaceae), a new butterwort from the Amotape-Huancabamba Zone (northern Peru)

Abstract The insectivorous genus Pinguicula occurs along the whole Andean mountain chain from Colombia-Venezuela in the north to Tierra del Fuego in the south with a short interruption in the Peruvian-Chilean desert range. This paper describes a new and striking species of Pinguicula that occurs in the south-eastern part of the Amotape-Huancabamba Zone in north Peru. It grows either as a lithophyte on moist rocks or as an epiphyte on Polylepis multijuga Pilg. in the wet highlands of the Cordillera Central. Pinguicula rosmarieae Casper, Bussmann & T.Henning, sp. nov. is clearly distinguished by a basal rosette of ovate-obovate leaves spread out flat on the ground and especially by a two-partite corolla with a straight uniform tube-spur complex, two features unknown from other Andean Pinguicula species. The morphological similarity to P. calyptrata Kunth is discussed and the habitat and distribution of P. rosmarieae are characterised.


Introduction
In South America, the insectivorous genus Pinguicula (Lentibulariaceae) is represented by seven at first sight ± closely related, although not well-known taxa: P. antarctica Vahl, P. calyptrata Kunth, P. elongata Benj., P. involuta Ruiz & Pav., P. jarmilae Halda & Malina, P. nahuelbutensis Gluch and the here newly described P. rosmarieae Casper, Bussmann & T.Henning. Forming a nearly continuous chain of ± vicarious species, the taxa occur over a distance of 8,500 km in the Andes from the north (Colombia, Santa Marta) via Venezuela, Ecuador, Peru, Bolivia and Chile to the extreme south (Chile, Argentina: Tierra del Fuego), with a gap between ~30°S and ~36°S in the Peruvian-Chilean arid region. This "Atacama"-gap has been bypassed (perhaps in former cooler and wetter periods). In northern Peru (~ 05°30'-06°30'S), the 'páramo-butterwort' P. calyptrata is more or less replaced by the litho-/epiphyte P. rosmarieae and, further to the south, the 'Jalca-Puna'-butterworts P. involuta and P. jarmilae close the gap.

Collection history
In 2017, searching for material of P. involuta during his study of the South American Pinguicula taxa, the first author came across the Catalogue of the Flowering Plants and Gymnosperms of Peru (Peru Checklist) (https://www.tropicos.org/Project/ PEC). At first sight, he believed that the specimen MO 6607881 (Paniagua Zambrana, Bussmann & Vega Ocaña 8586), designated as Pinguicula, could represent a new species, but more information, especially photos and, ideally, additional material was needed to confirm this initial assumption. The plants were gathered in November 2012 in the eastern Andes of north Peru in the area surrounding the Laguna Huayabamba ("Huayllabamba") and described as growing on a vertical rock wall in the spray of a small waterfall. The collectors located the sampled population in the Department La Libertad, but, instead, they were already in the adjacent Department San Martín.
Further investigations drew the attention to another, earlier collection (May 2001: T. Henning and C. Schneider 275) deposited in the Berlin herbarium (B) at the BGBM. They collected a violet-white flowering Pinguicula growing in large stands on moist rock surfaces in the cliffs forming the southern limit of the Laguna de los Cóndores (~06°51'S, ~77°42'W), ca. 20 km east of Leymebamba (B 100136109, B 100136110; duplicate specimens in HUT). The original label indicates "Departamento Amazonas, Province Chachapoyas". However, the Laguna and the adjacent area are part of the Department San Martín and situated some 4-5 km east of the border to the Department Amazonas. These specimens enabled the first author to conduct morphological comparisons with the material at MO for a thorough investigation. The collections showed the same taxon from a different population some 15 km further north in the same mountain range. The morphological differences to the other Peruvian Pinguicula species proved to be stable, at least in these two populations sampled independently and, together with the reported peculiar habitat preferences, enough to justify the description of a new species.
Finally, just very recently (2019), a third population has been reported and documented photographically by Lázaro Santa Cruz Cervera (USM) from the province of Bongará in the Department Amazonas, some 100 km further north.

Taxonomic background
During the process of describing the new species, the most important Peruvian herbaria in Lima (USM) and Trujillo (HUT) have been contacted in order to locate the duplicates and gather information about potential additional collections and records. After a review of all herbarium material that we could get access to, it became apparent that most of the Pinguicula-collections from north Peru have been misidentified as Pinguicula involuta. Instead, all collections made north of the Department Huánuco in central Peru belong to P. calyptrata, a species traditionally referred to as a Colombian-Ecuadorean taxon. This common misconception is due to the inadequate original description and the therein indicated distribution of these two Andean butterworts. Whereas P. calyptrata was collected by Humboldt and Bonpland (Humboldt et al. 1817) in Saraguro in the southern Ecuadorean province Loja, P. involuta was described by Ruiz and Pavon (1798) from Huánuco in central Peru and especially the latter is insufficiently characterised in the protologue (Casper and Hellwig 2019).
However, the distributional patterns revealed from the two previously described and the undescribed species draw a much clearer picture corresponding to the phytogeographic characteristics of the so-called Amotape-Huancabamba Zone (hereinafter: AHZ) (Weigend 2002). Instead of the (simplified) subdivision into a northern (P. calyptrata) and southern (P. involuta) taxon whose limits roughly correspond to the border between Peru and Ecuador, Pinguicula is present in the AHZ with two taxa, one occurring in the west stretching northwards (P. calyptrata) and one endemic to the eastern slope of the Peruvian Andes (P. rosmarieae). South of the AHZ, they are replaced by the widespread P. involuta whose distribution extends into Bolivia. The new taxon, Pinguicula rosmarieae Casper, Bussmann & T.Henning spec. nov. is here described as new to science. The morphology of the new species and its affinities to related taxa are illustrated and discussed. The coarse biogeographical patterns observed for the Peruvian species are outlined and explained in the context of the characteristics of the AHZ. A distribution map, based on collection data from revised herbarium material and a key to the Peruvian Pinguicula-species, is provided to enable a reliable determination of existing and future collections which is a crucial component of floristic studies as basis for urgent conservation efforts.
The present study is the first of a series of contributions at different stages of completion (Casper; Casper et al. in prep.), each dealing with a certain taxonomic or nomenclatural problem that became apparent in anticipation of a comprehensive synopsis of the South-American Pinguiculas that is in preparation and will be published soon. Therein, all questions regarding the historical biogeography as well as nomenclatural and taxonomic issues will be discussed extensively.

Materials and methods
The first author examined herbarium specimens of Pinguicula L. from South America in preparation for a revision of the Andean Pinguiculas at HUT, USM, MO, B and M (Thiers 2019) and from specimen scans using online databases (www.tropicos.org). This study combines the results of the herbarium studies, the experiences of the collectors (R.W. Bussmann and T. Henning) in the natural habitat and observations and reports kindly received from the Peruvian colleagues.
Description. Perennial rosette leaved herb with 1 (-4) flowered scapes. Rhizome ~ 10 mm long, with numerous adventitious fibrous roots. Leaves (4-) 6-10, flat on the ground, ± succulent (dried translucent-membranous), adult (20-) 30-40 (-50) mm long, nearly as long as wide, the blades ovate-obovate-oblong in outline, rounded at the tip attenuated to the base into a short petiole, the margins weakly (up to 3 mm) curled up, yellowish-green, upper surface of lamina covered with sessile glandular hairs. Hibernacula (winter buds, dormant buds) absent. Scapes 1-2 (-4), erect, (20-) 30 (-40) mm tall, terete, filiform (0.5-1 mm thick), one-flowered, green to reddishbrown, scattered with glandular hairs, often becoming glabrous or nearly so. Flowers small, ~8-10 (-11) mm long (including tube-spur-complex). Calyx two-lipped, green to pale brown to purple, upper surface of sepals scattered with stalked glandular hairs; upper lip divided deeply into three nearly equal-sized oblong lobes, at apex pointed; lower lip up to ½ divided into two oblong lobes, at apex pointed. Corolla two-lipped, bluish-magenta to white-violet; upper lip two-lobed, lobes obovate, ~5-6 mm long and ~2-3.5 mm wide, shallowly notched at the apex; lower lip larger and longer than the upper lip, with three oblong to obovate-oblong lobes (the median lobe somewhat larger than the two lateral ones), 4.5-5 mm wide, each distinctly (~1/5 to 1/3 of its length) notched. Tube (tube-spur-complex) at the throat funnel-shaped, on both sides broader than the spur, on the back side higher than the spur, proximally cylindrical   (nearly as long as wide), on the ventral side merging without any sharp angle into the cylindrical to cone-like stubby, at apex rounded, yellow-greenish spur; tube and spur forming a more or less uniform funnel-to cone-like straight, from the ventral side appearing as a box-like 'tube-spur-complex', ~6 mm long; the tube-spur-complex externally dark blue to purple lengthwise-striped by parallel veins. Palate bipartite, weakly developed (not clapper-like), inserted immediately behind (~1-2 mm) the corollas´ lower-lip middle lobe, yellow, set with short-stalked glandular hairs, proximally elongated into a short ventral hair strip; each of the two lateral corolla lobes with a small yellow hair bubble at their base, stretching proximally along on each side of the inner tube wall. Indumentum (apart from that visible in the photographs), stamens, pollen grains, ovary, stigma, capsule, seeds not seen. Chromosome number unknown.
Pinguicula rosmarieae is distinguished by its notable uniform funnel-cone-shaped straight tube-spur-complex, a feature unknown in any other Andean Pinguicula taxon. It is an endemic species, restricted to the eastern slopes of the Cordillera Central within the Amotape-Huancabamba-Zone of northern Peru (Departments Amazonas and San Martín; Fig. 4). It grows in rocky habitats, either under moving water or in the spray of small waterfalls and occasionally epiphytic on moss-covered twigs of Polylepis multijuga, at altitudes of about 2500 m-3100 m a.s.l. (Fig. 3).
Etymology. The new species is named after Dipl.-Biol. Rosmarie Casper, beloved wife and steady companion of the scientific efforts of S. J. Casper and mother of their children.

Affinities
Based on current floristic literature, Pinguicula involuta was considered as the only butterwort native in northern Peru. However, a revision of the available herbarium material in this study has revealed that this simple assumption, according to the historical taxonomic treatments, P. involuta is native to Peru whilst P. calyptrata is native to Ecuador, is largely incorrect. Furthermore, the "northern" Pinguicula of Humboldt and Bonpland (i.e. P. calyptrata), that was first discovered in the Saraguro range in southern Ecuador, has repeatedly been collected in northern Peru. We have seen specimens of P. calyptrata from the Peruvian Departments Piura, Amazonas, San Martín, Lambayeque and Cajamarca (Fig. 4, cf. the list of specimens below). In turn, P. involuta, so far, has never been collected in these Departments, although misidentified collections and erroneous floristic literature suggest that. Based on our observations and fieldwork, the northernmost locality of P. involuta is in the Department Huánuco in central Peru Fig. 4). At present, the exact distribution limits of P. involuta and P. calyptrata remain uncertain.
Morphological data indicate that the new taxon is distinct from P. involuta and P. calyptrata. A thorough study of South American Pinguicula is in preparation and will elucidate the morphological affinities amongst all relevant taxa.
Foliage: The leaf blades of P. rosmarieae are ovate-obovate-oblong, dried membranoustranslucent ( Fig. 2A) and spread out, i.e. they are not boat-like and they lack heavily curled-up margins (Fig. 1A, E): The whole rosette (up to 100 mm across) is not starshaped compared to P. calyptrata (Figs 1J, 2C) and P. involuta (field name of the latter in the original collection was P. stellata, see Casper and Hellwig 2019). The foliage shape of P. rosmarieae is similar to the geographically-distant P. albida Wright that occurs in Cuba and may represent an individual adaptation to the rocky, exposed habitats. Both habitats share nutrient-poor and often acidic white-sand-soils (for Peru: M. Weigend, pers. comm.). However, this observation is contradicted by the fact that the rosettes of P. calyptrata and P. involuta retain their star-like appearance on relatively open stands. Shape and posture of the foliage are, therefore, taxonomically meaningful for species delimitation.
Corolla: The violet-white to pale-bluish corolla is similar to that of most Andean Pinguicula: its lips are nearly equal-lobed (subisolobate). The two lobes of the upper-lip are (mostly only shallowly) notched at the distal margins ( Fig. 1B-D, F-H), the three lobes of the lower-lip are longer and at its distal margins deeply notched (up to ¼ -1/3 of its length; Fig. 1G-H). The most striking feature that separates P. rosmarieae from other Andean Pinguicula taxa is the more or less uniform straight tube-spur-complex that appears as almost entire. The typical tri-partite divided Pinguicula corolla (i.e. into corolla lobes, tube and spur) appears nearly bi-partite here and is divided only into the corolla lobes and the tube-spur complex. The funnel-shaped, cylindrical tube merges ventrally into the short and comparatively wide cone-shaped spur, lacking a sharp angle (Fig. 1A, B). The spur is stubby, rounded at the apex and light yellow-green. The back of the tube only weakly protrudes from the spur: from this point, the stubby spur slightly attenuates proximally and ends in an obtuse apex. Looking at the corolla from a lateral (Fig. 1B) or semi-ventral (Fig. 1C) perspective, the tube and spur are not markedly separated. The tube-spur-complex is lengthwise dark parallel-veined. A tripartite yellow to white palate is only weakly developed (Fig. 1H, i.e. non clapper-like as, for example, in P. calyptrata - Fig. 1I) and placed immediately behind the corolla lower-lip middle lobe (that appears as a shallow yellowish-greenish shimmering dent on the ventral tube-side directly behind the base of the middle lobe).
To illustrate the differences that can be observed on herbarium specimens, we have chosen Pinguicula calyptrata (Bussmann et al. 16447 MO, barcode: MO 6589755, Fig. 2C) collected in the immediate neighbourhood of the P. rosmarieae-type population ( Fig. 2A). The sheet shows three well-preserved, single-scaped flowering specimens with the flowers in lateral profile view. The leaf rosette with its curled-up leaf margins measures up to ~30 mm in diameter. The flowering scapes are up to ~50 mm tall; the flowers are up to ~12 mm long (spur included), the corolla is distinctly tri-partite into the lip, tube and spur; its lobes are nearly equal-sized (subisolobate), the lower-lip middle lobe is only slightly larger than the lateral lobes, ~5 mm long; the corolla tube is distinctly funnel-shaped (at throat widest, ~5 mm), about as long as the corolla lobes, ~5 mm long; the spur is distinctly separated from the tube, short, ~2.5 mm long, thin, at apex rounded (sometimes almost imperceptibly thickened), angled at about 60°-90° with the length axis of the tube. Overall, in P. calyptrata as in the other Andean Pinguicula-taxa, the corolla is distinctly divided into three parts: lip, tube and angled spur.
Contrarily, in P. rosmarieae, the corolla appears bi-partite: tube and spur form a straight uniform funnel-cone-shaped tube-spur-complex, i.e. the spur is not angled with the tube. These features are clearly visible on the specimen collected by Paníagua-Zambrana, Bussmann & Vega Ocaña 8586 (MO 6607881; Fig. 2B), gathered in the surroundings of the Laguna Huay(ll)abamba (Department San Martín). The plants were found growing either as lithophytes on a vertical rock wall in the spray of a small waterfall or as epiphytes on twigs of Polylepis multijuga. They are distinguished by a spread-out 6-8 leaved rosette appressed to the ground. Its flower shows the striking straight uniform tube-spur-complex which we also observed in the Laguna de los Cóndores-Pinguicula (see the three specimens on the left-hand side of the sheet). Photographs (Fig. 1H, I) of the corollas (frontal view) support the deep morphological disparity between the two taxa.
In P. rosmarieae (Fig. 1H), the corolla is widely open and appears radially symmetrical at first sight. The corolla lobes are spread out, the two lobes of the upper lip are smaller than those of the lower-lip, their distal margins are shallowly notched (to ~1/6 of their length). The lower-lip lobes are much larger, deeply notched (to ~¼ -1/3 of their length). The throat and the adjacent tube portion are not dark, a pronounced palate is not developed; it is replaced by a weak yellowish shimmering patch at the base of the corolla lower-lip middle lobe, continuing proximally (to the middle of the tubespur-complex) lengthwise in two white hairy stripes.
In P. calyptrata (Fig. 1I), the corolla is widely open and also appears radially symmetrical. The corolla lobes are spread out, covering each other slightly with their lateral margins. They are nearly equal in size, except for the middle-lobe of the lower-lip that dominates the corolla to a certain degree. The distal margins of all corolla lobes are only shallowly notched, the throat being dark-purple coloured. Nearly 2 mm behind (proximally) the middle lobe, at the base of the lower-lip, a pronounced yellow clapper-like palate is inserted, from which two white hairy stripes stretch out into the tube.

Habitat
The Departments Amazonas and San Martín in northern Peru partly occupy the Sierra zone between the dry coastal region (Costa) and the upper Amazon river lowlands (Selva) and are largely characterised by extensive and very species-rich, cloud forests and wet subalpine grasslands (páramos). In contrast to Pinguicula calyptrata, which is largely found on wet, often peaty, soils, in the páramo region, Pinguicula rosmarieae occupies a completely different, even wetter, habitat. The species has been found either growing on steep, often vertical, rock-walls, normally on sandstones, in the spray of waterfalls (Fig. 3A, B) or rarely as an epiphyte in dense moss layers on Polylepis multijuga (Fig. 3C). Both represent equally extreme habitats, with extremely wet, nutrientpoor and acidic conditions and considerable mechanical stress.
The population at the type location grew in full sunlight on a steep sandstone cliff immediately above the famous tombs built by the Chachapoyas culture (AD ca. 800-1500). The tombs were built underneath natural overhangs, thereby allowing dry storage of the mummies. The type population (Henning & Schneider 275) grows above these overhangs exposed to constant dripping water and the general high precipitation typical for the eastern slopes of the Andes in this region (Fig. 3A).

Distribution
Pinguicula rosmarieae is endemic to the northernmost foothills of the Cordillera Central in northern Peru. The herbarium specimens, known so far, are from three nearby collections in the same mountain range southeast of Leymebamba, stretching over some 15 km in a north-south direction. Both expedition teams have mistakenly located the collection sites in the adjacent western Departments (Amazonas and La Libertad, respectively), since the border runs along the pass of the Cordillera. According to current online map-sources (Google maps), all populations, deposited in herbaria so far, were found some 4-6 km east of the border to San Martín (Fig. 4). The presumed narrow endemism has just recently been rebutted by the report of the new taxon from the Province of Bongará in the Department Amazonas some 100 km further north. Photographs made by L. Santa Cruz Cervera clearly show the characteristic rosette and flower patterns of P. rosmarieae, photographed in a similar open habitat near the famous Gocta falls. However, the taxon seems restricted to the northern branches of the Cordillera Central, but reaches further into the northernmost foothills. The collection data indicate that P. calyptrata and P. rosmarieae show distributional overlap over the entire range of the latter. True sympatry is nevertheless prevented by the different habitat requirements of the two taxa.
The area lies well in the so-called Amotape-Huancabamba Zone, an important biodiversity-hotspot that spans from the Pacific coast over the cordilleras to the tropical lowlands of southern Ecuador and large parts of northern Peru (Fig. 4, for details see: Weigend 2002Weigend , 2004). Many plant groups have a centre of diversity here (Weigend et al. 2005;Struwe et al. 2009;Deanna et al. 2018) and show a concentrated occurrence of narrow-endemic taxa in that region (Berry 1982;Ayers 1999;Weigend 2002;Weigend 2009, 2009a;Henning et al. 2019). While the vegetation and flora of the inner-Andean valleys and the western slopes are relatively well-investigated, the eastern flanks of the Cordillera Central facing Amazonia are still under-collected in many areas. Especially, the areas east of Leymebamba (Dept. Amazonas) in the north and Buldibuyo (Dept. La Libertad) in the south remain largely unexplored, since the eastern slopes can only be reached by foot. Single collection trips have yielded unexpected, supposedly narrowly endemic taxa in other plant groups, although only a tiny fraction of the area could be sampled to date (e.g. Loasaceae: Nasa rugosa subspp. gracilipes and pygmaea; Henning et al. 2011).
The whole region is characterised by great geological diversity, with large areas of dolomitic karst, caused by the exceptionally high rainfall (the indigenous Chachapoya were often called "warriors of the clouds"), interspersed with small areas of sandstone outcrops and metamorphic rocks. The vegetation of the sandstone areas is particularly intriguing, with many endemic species and unique vegetation types (e.g. Weinmannia sp. and Polylepis multijuga-Iochroma stenanthum dominated forests). P. rosmarieae has been found exclusively in the spray of waterfalls on sandstone cliffs and as an epiphyte on Polylepis -both systems characterised by extreme moisture and almost permanent cloud cover, a fact that is recognised in the local topographic maps, which often simply indicate "clouds" in these areas. Pinguicula is yet another example of a plant group that is present in the Amotape-Huancabamba Zone with an endemic taxon, whereas its widespread relatives have their distribution limits at the zonal boundary, either seen from within (P. calyptrata) or outside (P. involuta). Since Pinguicula rosmarieae has been collected in those areas of the overall region that are comparatively easy to access, it cannot be ruled out that there are additional taxa awaiting discovery. However, the nondescript shape of the insectivorous butterwort, represented by only a few, widespread taxa outside of that region (Fig. 4), does not encourage gathering.
On a broader scale, the endemism of P. rosmarieae is by no means a unique phenomenon amongst the South American Pinguicula. P. jarmilae Halda & Malina from southeast Bolivia (Department Chuquisaca, municipio Villa Serrano, village Nuevo Mundo), for example, is only known from the type locality (Halda et al. 2007). Although it grows on vertical sandstone (laterite) rock faces under flowing/moving water, its morphology is quite different from that of P. rosmarieae: the superficial similarity is likely coincidental and does not reflect a close relationship between the two taxa.

Preliminary conservation status
Due to the aforementioned lack of a continuous botanical exploration of the region, we have to consider P. rosmarieae as Data Deficient (DD), according to the IUCN threatened species assessment guidelines (2001,2017). However, within its distributional range, it seems to be limited to the easternmost ridge of the Cordillera Central. As an insectivorous plant, it seems to be adapted to special habitat types, characterised by 'open' vegetation, high precipitation and nitrogen-poor soils. These habitats might only be available in a narrow altitudinal band along the mountain chain. As our observations suggest, such sites are not present at similar altitudes in the west and it is very likely that suitable habitats are only available a few kilometres further east up to the lower altitudes of the Andes. This might indicate that P. rosmarieae is generally a rare taxon and might, thus, be vulnerable to habitat destruction. The lack of additional collections emphasises this assumption. This delicate butterwort might be in danger of extinction, but more data is needed to better assess the entire distribution and abundance, especially to the east of the known populations.