[Botany • 2018] A Revision of Xylopia L. (Annonaceae): The Species of Tropical Africa

 D Xylopia aethiopica from Gabon E Xylopia longipetala from Mali, representing a record for the country not otherwise documented F Xylopia piratae from Ivory Coast G Xylopia odoratissima from Zambia H Xylopia arenaria from Tanzania

in Johnson & Murray, 2018.

  DOI:  10.3897/phytokeys.97.20975 

Abstract

A revision of the 45 species of the pantropical genus Xylopia in Tropical Africa includes descriptions of six new species and a new section of the genus. The fruits and seeds of Xylopia show specializations that promote vertebrate dispersal, primarily by hornbills and monkeys. Over half of the African species have an Area of Occupancy (AOO) less than 80 km2, suggesting that they are in need of protection. African species are classified into five sections. Section Neoxylopia , with four species, is centered in the Guineo-Congolian Region and includes Xylopia globosa sp. nov. Section Ancistropetala, with three species, occurs in the same region. Both of these sections are endemic to Africa. Section Xylopia, which extends to Madagascar and the American tropics, has only a single species in Africa, X. aethiopica. The three species of section Verdcourtia sect. nov. are restricted to the East African coast and Madagascar. The largest number of African species, (34) belong to section Stenoxylopia, in which the seeds lack the arils found in the other sections and instead have a fleshy sarcotesta. Section Stenoxylopia is divided into two informal groups, one centered in eastern and southern Africa (X. odoratissima group) and the other centered in the wetter forests of western and central Africa (X. acutiflora group). Five new species are described in section Stenoxylopia: Xylopia nilotica sp. nov. from Sudan, South Sudan, and Uganda, Xylopia calva sp. nov. from Nigeria and Cameroon, which is allied to X. phloiodora, and Xylopia monticola sp. nov. from Nigeria and Cameroon, X. piratae sp. nov. from Ivory Coast and Ghana, and X. unguiculata sp. nov. from Gabon. The latter three species are segregates of the former Xylopia acutiflora s. l. One new combination is made at the species level, X. shirensis comb. nov. Keys, descriptions, illustrations, distribution maps, and an index to numbered collections document diversity and assist with species identification. The name Unona oliveriana Baill. was found to pre-date the name Unona lepidota Oliv., requiring the combination Meiocarpidium oliverianum comb. nov.

Keywords: Xylopia, pantropical Annonaceae, Tropical Africa, long distance dispersal, bird/monkey syndrome, X. aethiopica, conservation, new species

Figure 3. Flowers of representative Xylopia species.
A Flower from type collection of Xylopia globosa from Gabon B Xylopia tenuipetala from Mozambique C Xylopia quintasii from Gabon D Xylopia aethiopica from Gabon E Xylopia longipetala from Mali, representing a record for the country not otherwise documented F Xylopia piratae from Ivory Coast G Xylopia odoratissima from Zambia H Xylopia arenaria from Tanzania I Xylopia collina from Tanzania.

A, D by Thomas L. P. Couvreur B by Frances Chase C by Ehoarn Bidault E by Philip Birnbaum F by Céline Pirat G by Warren McClelland H and I by D. M. Johnson.

Xylopia globosa D. M. Johnson & N. A. Murray, sp. nov.

Xylopia nilotica D. M. Johnson & N. A. Murray, sp. nov.

 Xylopia calva D. M. Johnson & N. A. Murray, sp. nov.

 Xylopia monticola D. M. Johnson & N. A. Murray, sp. nov.

Xylopia piratae D. M. Johnson & N. A. Murray, sp. nov.

Figure 4. Fruits and seeds of representative Xylopia species.
A Xylopia staudtii from Democratic Republic of the Congo B Xylopia aethiopica from Republic of the Congo C Xylopia quintasii from Cameroon D Xylopia tenuipetala from Mozambique E Xylopia collina from Mozambique F Xylopia gracilipes from Mozambique G Xylopia hypolampra from Gabon H Xylopia tanganyikensis from Tanzania.

A by Quentin Luke B by David Harris C, G by Thomas L. P. Couvreur D by Jonathan Timberlake E, F by Mervyn Lötter H by Noriko Itoh. C reproduced with permission of Thomas L. P. Couvreur and of the American Society of Plant Taxonomists D reproduced with the permission of Jonathan Timberlake and of the Board of Trustees, Royal Botanic Gardens Kew.

 David M. Johnson and Nancy A. Murray. 2018. A Revision of Xylopia L. (Annonaceae): The Species of Tropical Africa.  PhytoKeys. 97: 1-252.  DOI:  10.3897/phytokeys.97.20975

[Ecology • 2017] The Ecological Significance of Secondary Seed Dispersal by Carnivores

Abstract

Animals play an important role in the seed dispersal of many plants. It is increasingly recognized, however, that the actions of a single disperser rarely determine a seed's fate and final location; rather, multiple abiotic or animal dispersal vectors are involved. Some carnivores act as secondary dispersers by preying on primary seed dispersers or seed predators, inadvertently consuming seeds contained in their prey's digestive tracts and later depositing viable seeds, a process known as diploendozoochory. Carnivores occupy an array of ecological niches and thus range broadly on the landscape. Consequently, secondary seed dispersal by carnivores could have important consequences for plant dispersal outcomes, with implications for ecosystem functioning under a changing climate and across disturbed landscapes where dispersal may be otherwise limited. For example, trophic downgrading through the loss of carnivores may reduce or eliminate diploendozoochory and thus compromise population connectivity for lower trophic levels. We review the literature on diploendozoochory and conclude that the ecological impact of a secondary vs. primary seed disperser depends on the relative dispersal distances, germination success, and the proportion of seeds exposed to secondary dispersal by carnivores. None of the studies up to present day have been able to rigorously assess the ecological significance of this process. We provide a framework of the components that determine the significance of diploendozoochory across systems and identify the components that must be addressed in future studies attempting to assess the ecological importance of diploendozoochory.

Conclusions

Several authors have suggested that polychory is likely a much more common phenomenon than has been previously assumed (Ozinga et al. 2004, Vander Wall and Longland 2004) and can be more beneficial for the dispersing plant than single-phase dispersal (Vander Wall and Longland 2004). While these studies have largely concentrated on abiotic vectors and short-distance, second-phase dispersal by invertebrates and scatter-hoarding rodents, the impact of carnivores may be similarly important, particularly in discontinuous habitats. Secondary dispersal by carnivores is by no means exclusive of the types of diplochory defined by Vander Wall and Longland (2004); rather, it is very likely that further seed transport by ants, dung beetles, or scatter-hoarding rodents often occurs after seeds are deposited by the secondary disperser.

Our framework provides guidelines for future research, with predictions that should aid in targeting systems that are likely to be most affected by carnivore involvement in seed dispersal. In addition to disrupting heavy seed predation pressure, carnivores that intercept large proportions of a plant population's seeds and significantly alter the germination or recruitment success of seeds relative to the primary disperser will most likely be an important ecological force for the plant species and, possibly, the community structure. Another important role for far-ranging secondary dispersers may involve long-distance dispersal or gene flow between remote populations or habitat fragments. While carnivore effects will likely be small in most systems, such circumstances may indeed result in secondary seed dispersers significantly influencing plant range shifts, dispersal success, fitness, and potentially species viability.

It is currently unknown how important the phenomenon is ecologically, but given its potentially vast prevalence and the possible implications, it is possible that ignoring it could impair the interpretation of broad ecological patterns or hinder conservation efforts. Considering diploendozoochory as a part of the dispersal mechanism of plants can potentially improve modeling outcomes for range shifts due to climate change, or help explain current plant distributions, as historical effects of carnivores (or other large-bodied animals; Pakeman 2001) may have influenced plant movement rates. Where the secondary disperser facilitates different dispersal processes than are accomplished by other means of dispersal, carnivore involvement may have important consequences for the spread of invasive plant species, as well as the ability of plants to adapt to habitat loss and changing climatic conditions. Where such relationships exist, the extinction or decline of involved species can affect multiple trophic levels and disrupt ecosystem functions.

Anni Hämäläinen, Kate Broadley, Amanda Droghini, Jessica A. Haines, Clayton T. Lamb, Stan Boutin and Sophie Gilbert. 2017. The Ecological Significance of Secondary Seed Dispersal by Carnivores.  Ecosphere. 8(2)   DOI:   10.1002/ecs2.1685 

Research shows secondary seed dispersal by predator animals is important for recolonization of plants http://phy.so/407067281 via @physorg_com

[Botany • 2015] Thismia hongkongensis • A New Mycoheterotrophic Species (Thismiaceae) from Hong Kong, China, with Observations on Floral Visitors and Seed Dispersal

 Thismia hongkongensis S.S.Mar & R.M.K.Saunders

Flower structure in Thismia hongkongensis sp. nov. A Mature flower, showing outer tepals (ot), inner tepals (it) and abscission zone (ab) at the base of the perianth tube. B Entire plant (S.S. Mar 1, HK).

doi: 10.3897/phytokeys.46.8963

Figure 1. Flower development in Thismia hongkongensis sp. nov.
A, B Root system, with young flowering stalk developing (arrowed). C–G Developing flower, photographed over a 17-day period (10th, 14th, 16th, 19th and 23rd May, respectively) (S.S. Mar 1, HK). I, J Post-fertilization flower, showing abscission of perianth tube.

Photos by S.S. Mar. doi: 10.3897/phytokeys.46.8963

Abstract

A new species, Thismia hongkongensis S.S.Mar & R.M.K.Saunders, is described from Hong Kong. It is most closely related to Thismia brunonis Griff. from Myanmar, but differs in the number of flowers per inflorescence, the colour of the perianth tube, the length of the filaments, and the shape of the stigma lobes. We also provide inferences on the pollination ecology and seed dispersal of the new species, based on field observations and interpretations of morphology. The flowers are visited by fungus gnats (Myctophilidae or Sciaridae) and scuttle flies (Phoridae), which are likely to enter the perianth tube via the annulus below the filiform tepal appendages, and exit via small apertures between the filaments of the pendent stamens. The flowers are inferred to be protandrous, and flies visiting late-anthetic (pistillate-phase) flowers are possibly trapped within the flower, increasing chances of pollen deposition on the receptive stigma. The seeds are likely to be dispersed by rain splash.

Keywords: Burmanniaceae, China, mycoheterotrophic, pollination, rain splash dispersal, Thismia, Thismiaceae, new species

Figure 3. Fruit structure in Thismia hongkongensis sp. nov.
A Flower (rear right), immature fruit, shortly after fertilization (left), and mature fruit with exposed seeds (front). B Two fruiting individuals, each with three fruits.

 Photos by S.S. Mar. doi: 10.3897/phytokeys.46.8963

Figure 3. Fruit structure in Thismia hongkongensis sp. nov.
C Lateral view of fruiting specimen, illustrating elongated fruit stalk. D Mature fruit with exposed seeds. E Dehydrated fruit. F Rehydrated fruit, after rainfall.

Photos by S.S. Mar. doi: 10.3897/phytokeys.46.8963

Shek Shing Mar and Richard Saunders. 2015. Thismia hongkongensis (Thismiaceae): A New Mycoheterotrophic Species from Hong Kong, China, with Observations on Floral Visitors and Seed Dispersal. PhytoKeys 46: 21-33. doi: 10.3897/phytokeys.46.8963