Short Corolla Tube Research Articles

Genetic structure of interspecific hybridization between the long corolla tube species, Isodon longitubus, and its short corolla tube congener, I. inflexus

Genetic structure of interspecific hybridization between the long corolla tube species, Isodon longitubus, and its short corolla tube congener, I. inflexus

Asymmetrical disassortative pollination mediated by long-/short-tongued pollinators in a distylous Limonium myrianthum (Plumbaginaceae) with a short corolla tubular small flower.

In heterostylous plants, short-tongued pollinators are often ineffective/inefficient owing to the limitations imposed by a long corolla tube. However, it is unclear how disassortative pollen transfer is achieved in small flowers. We investigated the pollination pattern and floral morph variation by analyzing heterostylous syndrome, pollinator groups, and pollen deposition after a single visitation in two Limonium myrianthum populations with short-corolla-tubular small flowers. The predominant pollinators in the Hutubi population were pollen-seeking short-tongued syrphids, which can only transfer pollen between high-level sexual organs. In the Xishan population, nectar-seeking short-tongued insects were efficient pollinators with symmetrical disassortative pollen transfer between high- and low-level sexual organs, whereas long-tongued pollinators had a low efficiency between high-level sexual organs due to the low contact probability with the stigma of long-styled flowers (L-morph), which no longer offered the same advantage observed in tubular flowers. Asymmetrical disassortative pollination may cause the female fitness of short-styled (S-morph) individuals in the Hutubi and L-morph individuals in the Xishan population to suffer greater selection pressure and exhibit a higher degree of floral morph variation. Limonium myrianthum exhibits an unusual pollination pattern in which the small flowers with short corolla tubes make it possible for short-tongued insects to become effective pollinators. However, factors such as the position of stigma-anther within the flower, pollinator species and their preference further caused asymmetrical disassortative pollen transfer. Therefore, more factors should be considered when evaluating the effectiveness of short- and long-tongued insects in pollination service.

Nyctocalos tunjuharii (Bignoniaceae), a new species from Sabah, Malaysian Borneo

Nyctocalos tunjuharii (Bignoniaceae) is described and illustrated as a new species from Mt Kallang, Tenom, Sabah, Malaysian Borneo. It is distinguished from N. cuspidatus by its longer, linear calyx teeth, shorter corolla tube and included stamens that reachless than half the length of the upper dilated part of the corolla tube. This species is restricted to an area near Mt Kallang, Tenom, Sabah. A preliminary conservation status assessment is presented and a key to the Malesian taxa is provided.

A new species of Argyreia (Convolvulaceae) from Yunnan, China.

Argyreiasubrotunda, a new species from Yunnan Province, China, is described and illustrated. The new species resembles A.fulvocymosa and A.wallichii, but differs from these in the flowers with an entire or shallowly lobed corolla, as well as smaller elliptic bracts, lax flat-topped cymes and shorter corolla tubes. An updated key to the species of Argyreia from Yunnan province is also provided.

Pollinator Proboscis Length Plays a Key Role in Floral Integration of Honeysuckle Flowers (Lonicera spp.).

Pollinator-mediated selection is supposed to influence floral integration. However, the potential pathway through which pollinators drive floral integration needs further investigations. We propose that pollinator proboscis length may play a key role in the evolution of floral integration. We first assessed the divergence of floral traits in 11 Lonicera species. Further, we detected the influence of pollinator proboscis length and eight floral traits on floral integration. We then used phylogenetic structural equation models (PSEMs) to illustrate the pathway through which pollinators drive the divergence of floral integration. Results of PCA indicated that species significantly differed in floral traits. Floral integration increased along with corolla tube length, stigma height, lip length, and the main pollinators' proboscis length. PSEMs revealed a potential pathway by which pollinator proboscis length directly selected on corolla tube length and stigma height, while lip length co-varied with stigma height. Compared to species with short corolla tubes, long-tube flowers may experience more intense pollinator-mediated selection due to more specialized pollination systems and thus reduce variation in the floral traits. Along elongation of corolla tube and stigma height, the covariation of other relevant traits might help to maintain pollination success. The direct and indirect pollinator-mediation selection collectively enhances floral integration.

Are floral traits and their phenotypic variability related to plants with generalized or specialized pollination systems? A community perspective

Flower traits under selection by specialized pollinators may experience a decrease in their phenotypic variation. Another viewpoint suggests that flower traits of plants under selection by generalized pollinators could display comparable variability to that of plant species with a specialized pollination system. We evaluated the following alternatives: (a) species with specialized pollination system (zygomorphic flowers, long corolla tube and higher amount of nectar, and visited by only one group of pollinators) will present higher natural fruit set and less floral phenotypic variation in comparison with species with generalized pollination system (actinomorphic flowers with short corolla tube and comparatively lower amount of nectar, and visited by a wide spectrum of taxonomically diverse pollinator species); (b) alternatively, if species with generalized pollination system show similar reproductive success to that of with specialized pollination system, comparable phenotypic variation in flower traits will be expected between them. Natural fruit set, corolla tube length, amount of nectar per flower, nectar sugar composition, and variability of these floral traits were measured in 43 biotically-pollinated species growing in a Chaco Serrano community from central Argentina. Plants were classified as specialists or generalists based on focal observations made to record their pollinators. Correlations and General Linear Models were used to compare fruit set and flower traits between plant species with generalized and specialized pollination system. Plants with specialized pollination system display flowers with higher amounts of nectar than plants with generalized pollination system. Nevertheless, species with generalized and specialized pollination system showed similar fruit set and floral phenotypic variation (except for the percentage of sucrose). The trends observed in species with generalized or specialized pollination systems from the Chaco forests suggest that pollinators could be an effective evolutionary force in selecting primary and secondary floral traits for both types of plant species.

Inselbergs Again: Four New Species ofMandevilla(Apocynaceae) from Brazil

Abstract—Four new species ofMandevillafrom inselbergs in Espírito Santo, Brazil are described, including illustrations, and maps.Mandevilla declinataresemblesM. crassinodabut differs by leaf blades acuminate to long acuminate and longer corolla.Mandevilla fornograndensisis distinguished from morphologically similar species by its yellow corolla.Mandevilla mysteriosais morphologically similar toM. lucidabut differs by its longer petioles, leaf blade characters, shorter corolla tube, and smaller anthers;Mandevilla obovataresemblesM. hatschbachii,but it is separated by its puberulent leaves, longer sepals, and white corolla. An informal evaluation of the conservation status according to IUCN guidelines is proposed for each species:M. declinata(VU: D2),M. fornograndensis(VU: D2),M. mysteriosa(VU: D2), andM. obovata(VU: B1ab(i,ii,iii)+2ab(i,ii,iii)). A key to the species ofMandevillain Espírito Santo is included.

Oreocharispolyneura, a new species of Gesneriaceae from southern Yunnan, China.

Oreocharispolyneura, a new species from southern Yunnan, China, is described and illustrated. It is morphologically similar to O.rhytidophylla by having more obvious lateral veins forming a crosslinked network on the adaxial surface of leaf blades, but can be distinguished by having more lateral veins (12-15 pairs vs. 7-9 pairs) of leaf blades, shorter corolla tubes (the length ratio of corolla tube to corolla lobes = 1.2-2.9 vs. 3.4-6) and shorter pistils (6-8 mm long vs. 27-30 mm long). In addition, a detailed morphological description, a photographic illustration, the distribution and phenology of the new species are presented.

Floral trait variation across individual plants within a population enhances defense capability to nectar robbing

Floral trait variation may help pollinators and nectar robbers identify their target plants and, thus, lead to differential selection pressure for defense capability against floral antagonists. However, the effect of floral trait variation among individuals within a population on multi-dimensional plant-animal interactions has been little explored. We investigated floral trait variation, pollination, and nectar robbing among individual plants in a population of the bumble bee-pollinated plant, Caryopteris divaricata, from which flowers are also robbed by bumble bees with varying intensity across individuals. We measured the variation in corolla tube length, nectar volume and sugar concentration among individual plants, and evaluated whether the variation were recognized by pollinators and robbers. We investigated the influence of nectar robbing on legitimate visitation and seed production per fruit. We found that the primary nectar robber (Bombus nobilis) preferred to forage on plants with long-tubed flowers, which produced less nectar and had lower sugar concentration compared to those with shorter corolla tubes. Individuals with shorter corolla tubes had comparatively lower nectar robbing intensity but higher visitation by legitimate visitors (mainly B. picipes) and higher seed production. Nectar robbing significantly reduced seed production because it decreased pollinator visits. However, neither pollination nor seed production differed between plants with long and short corolla tubes when nectar robbers were excluded. This finding suggests that floral trait variation might not be driven by pollinators. Such variation among individual plants thus allows legitimate visitors and nectar robbers to segregate niches and enhances population defense against nectar robbing in unpredictable conditions.

Secondary contact and adaptation to local pollinator assemblages mediate geographical variation in corolla length in Isodon shikokianus

AbstractAdaptation to local pollination regimes and secondary contact of allopatrically differentiated populations with respect to pollination ecology may result in geographical variation in floral traits. We examined the contributions of these two processes in Isodon shikokianus, which showed remarkable geographical variation in corolla tube length in western Japan. Corolla tube length varied among 17 study populations located within a relatively narrow area, and covaried with altitude and distribution of two bumblebee pollinators with different tongue lengths: the longer corolla was found at lower altitudes where the long‐tongued pollinator was more abundant, and vice versa. Additionally, bumblebee species preferentially visited flowers that fit their tongue lengths. Population genetic analysis based on 11 microsatellite loci revealed that populations with long and short corolla tubes constituted genetically distinct groups. Migration rates were low between the groups, but high within each group. These results indicate that two genetically differentiated groups made secondary contact and hybridized, and gene flow between the groups was limited. Thus, the geographical variation in corolla tube length in I. shikokianus may be a result of past allopatric differentiation and subsequent secondary contact of populations with different corolla tube lengths. The variation in corolla tube length within a narrow area may be maintained by selection owing to the altitudinally structured pollinator assemblages. Altitudinal differences in relative abundance of two pollinators and their assortative visitation with respect to corolla tube length may contribute to reproductive isolation between the two groups.

A new coffee species from South-West Cameroon, the principal hotspot of diversity for Coffea L. (Coffeeae, Ixoroideae, Rubiaceae) in Africa

Coffea rizetiana Stoff. & M.Noirot, sp. nov., a diploid species only known from a single wild population in South-West Cameroon, is formally described here. It is probably extinct in the wild, but is present in the germplasm collection in Bassin Martin (Réunion, France) and Meise Botanic Garden (Belgium). Phylogenetic analyses reveal a close relationship with C. montekupensis Stoff., a species endemic to the same region but occurring at higher elevations, and with C. liberica Bull. ex Hiern, a species with a wide Central and West African distribution. The new species can be distinguished from other Coffea species from Central Africa by its large black fleshy fruits with thick mesocarp. It can be differentiated from its close relative C. montekupensis by its larger less obovate leaves, longer corolla tube and larger fruits; and from C. liberica by its shorter petiole, acuminate leaf tip, cuneate leaf base, thinner leaf blade, shorter corolla tube, longer corolla lobes and black fruits with a thick fleshy pericarp. The evolutionary importance of the fruit colour is discussed, as well as the role of Mount Kupe, the Bakossi Mountains and the broader South-West Cameroon region as the principal Coffea diversity hotspot on the African continent.

A New Distinctive Species ofSchizanthus(Solanaceae) and the Reinstatement ofSchizanthus fallax

Abstract—A newSchizanthusspecies from northern Chile is described and illustrated.Schizanthus nutantifloruswas discovered based on recent collections made during unusual rain events in the Atacama Desert in 2015. The new species is distinguished morphologically from otherSchizanthusspecies from northern Chile by its short corolla tube, with a distinct upper lip arrangement and colour, having the longest lower lip, and downward-facing flowers. Additionally, the reinstatement ofSchizanthus fallaxis proposed. By using both nDNA and cpDNA, phylogenetic relationships among all species ofSchizanthuswere investigated. Molecular and field observations, as well as an exhaustive morphological revision of fresh material and herbarium specimens, supports the segregation ofSchizanthuswith short corolla tubes from northern Chile into three species. We propose that, in order to fully understand both the taxonomy and evolution ofSchizanthus, an integrative framework encompassing molecular, ecological, and morphological data should be carried out. Information on distribution, habitat, informal conservation status, as well as taxonomic notes and illustrations are provided. In addition, an updated key for the species ofSchizanthusfrom northern Chile is given.

Madhuca balakrishnanii (Sapotaceae), a new species from Kerala, India

Madhuca balakrishnanii (Sapotaceae), a new species from Kerala is here described with photographs. It is most closely similar to M. diplostemon and M. insignis but differs in having long stipules, sparsely hairy pedicels, abaxially hairy inner sepals, shorter corolla tubes with oblong lobes, fairly long densely hairy staminal filaments, shorter styles and ovoid fruits. The IUCN conservation status, ecology, distribution and phenology along with a key for the identification of Madhuca species in the Western Ghats is provided.

Siphocampylus nebularis (Campanulaceae, Lobelioideae), a New Endemic Species from the Atlantic Forest in Southern Brazil

Abstract—Siphocampylus nebularis is a new species endemic from the Serra do Mar mountain range in the Paraná state, Brazil. It is morphologically close to S. fulgens due its alternate phyllotaxis, sparsely denticulate leaves, and flowers with reddish corolla tube, differing mainly by the shorter corolla tube, longer calyx lobes, and coriaceous leaves observed in the new species. The new taxon is here described and illustrated. We also propose the inclusion of S. nebularis in the IUCN Red List as an endangered (EN) species due its narrow distribution and the decline of the quality of its habitat.

A new species of Psydrax (Vanguerieae, Rubiaceae) from the Gia Lai Plateau, southern Vietnam.

A new species of Rubiaceae, Psydraxgialaiensis B.H.Quang, T.B.Tran & V.S.Dang, sp. nov., is described and illustrated from the Kon Chu Rang Nature Reserve, Gia Lai Province, southern Vietnam. This species is characterized by having strigose branches and leaves, a conspicuously bulging, short corolla tube, an accrescent nectary disc and a style with a dense tuft of hairs, which clearly distinguishes it from the other species in the genus. A description, vernacular name, conservation assessment, illustration, photographs, and a key to the species of Psydrax in Vietnam are provided.

Cotyledon tanquana, a New Species from the Tanqua Karoo Region, Western Cape, South Africa

A new Cotyledon is described from the Tanqua Karoo in the Western Cape. Cotyledon tanquana is a distinct succulent shrublet from the lower eastern slopes of the Cedarberg Mountains and rocky terrain in the Succulent Karoo. It differs from Cotyledon orbiculata var. orbiculata by its distinctly cuneiform glandular hairy dull-green leaves and short dull-reddish corolla tube 15–17 × 5–8 mm bearing horizontally spreading transversely oblong yellowish squamae 2 × 1 mm, truncate at the apex.

Taxonomic studies on Ophiorrhiza in Vietnam I: Ophiorrhiza hiepii and O. hainanensis, a new species and new record from northern Vietnam

Ophiorrhiza hiepii and O. hainanensis are reported as a new species and a new record for Vietnam respectively. O. hiepii is morphologically similar to O. subrubescens but differs by its smaller habit, usually unbranched stems, fewer secondary veins, umbelliform and sub-congested cymes, shorter corolla tubes and shorter stigma lobes in short-styled flowers. The mature flowers of O. hainanensis, which were unknown before, were measured in the wild for supplemental description of its floral characters. Additionally, the relationship between O. hainanensis and O. nutans, two easily confused species is clarified.

Reversal versus specialization in floral morphological evolution in Petrocosmea (Gesneriaceae)

AbstractA widely held hypothesis in evolution is that adaptive specialization constrains the potential direction of future evolutionary change and thus may be irreversible, also known as Dollo's law. However, this hypothesis has long been subject to debate in evolutionary biology. Floral specialization is intriguing as it is usually linked to reproductive isolation and could affect speciation. Here, following the discovery of four new taxa, we observed some interesting phenomena of reversal versus specialization in morphology in a clade with the most specialized flowers in the genus Petrocosmea. In the phylogenetic tree based on sequences of multiple DNA regions, the morphological reversals, especially the regain of a long corolla tube, are nested within the branches characteristic of normally specialized flowers with a short corolla tube and highly specialized zygomorphy. Our results indicate that the highly specialized floral organ of this clade is still actively evolving in multiple branches toward specialization while reversals to different ancestral states occur in some branches. Great disturbance of ecological environment is likely a crucial factor affecting trait reversibility, such as the rapid uplift of the Himalayan–Tibetan plateau. The four new taxa are treated herein taxonomically. The flowers of this clade represent an interesting model to explore the genetic basis underlying the evolutionary reversal versus specialization and the interplay between genetic factors and environmental variables.

Hedyotis tonggulingensis (Rubiaceae): A new species from Hainan, China

Hedyotis tonggulingensis is described as a new species from China. It is similar to the sympatric species H. hainanensis, but obviously differs in having tetragonal stems with narrow wings, terminal and axillary inflorescences and the short corolla tubes. The phylogenetic analysis revealed that H. tonggulingensis was closely related to the sympatric species of H. pardifolia and H. yazhouensis but not to H. hainanensis. It was evaluated as Least Concern because of its abundant individuals, little economic use and well protected habitat.

Argostemma vietnamicum (Rubiaceae), a New Species from Vietnam

Argostemma vietnamicum B.H. Quang, Joongku Lee & R.K. Choudhary, a new species of Rubiaceae from Thua-Thien Hue Province of central Vietnam is described and illustrated. It is morphologically similar to A. discolor and A. bariense, but differs from them by having considerably shorter petioles, round to obovate leaf laminae with a round base, obsolete secondary veins, 1–4-flowered inflorescences, much shorter peduncles and pedicels, different bracts, a glabrescent to glabrous calyx, and a shorter corolla tube. An identification key to the species of Argostemma known from Vietnam is provided.