Helen C. F. Hopkins

Reticulate evolution on a mosaic of soils: diversification of the New Caledonian endemic genus Codia (Cunoniaceae)

We reconstructed the evolutionary history of Codia, a plant genus endemic to the New Caledonia biodiversity hotspot in the southwest Pacific, using three single‐copy nuclear genes. It seems likely that more than half of Codia species have a hybrid origin, but in the absence of cytological information, it is not known whether polyploids occur. Adaptation to ultramafic soils is possibly a plesiomorphic character for the entire genus. We found that species of hybrid origin can have some morphological characters absent in putative parental species, that is, they exhibit transgressive phenotypes. There is evidence of considerable range alteration post‐origin in several species because some likely parental species of hybrid taxa no longer co‐occur and are confined to putative rainforest refugia; in some cases, hybrid species do not now co‐occur with either of their parental species. These results have implications for the design of conservation strategies, for example, prioritization of parental species for ex‐situ conservation and preservation of the contact zones between soil types where hybridization is more likely to occur (i.e. conserving the possibility for the process to continue rather than trying to conserve taxa).

The Indo-Pacific species of Parkia (Leguminosae: Mimosoideae)

Summary. Twelve species of the pantropical genus Parkia R.Br., which occur from NE India to Fiji, are enumerated and illustrated. They include petai (P. speciosa) which is eaten as a spicy vegetable in SE Asia. All belong to section Parkia, and they appear to be more closely related to the African species of this section than to the American ones. A key and distribution maps are given. Scattered references indicate that pollination is by both large and small pteropodid bats, and a variety of animals, including monkeys and birds, are potential dispersal agents.

Cryptic adaptive radiation in tropical forest trees in New Caledonia

The causes of the species richness of tropical trees are poorly understood, in particular the roles of ecological factors such as soil composition. The nickel(Ni)-hyperaccumulating tree genus Geissois (Cunoniaceae) from the South-west Pacific was chosen as a model of diversification on different substrates. Here, we investigated the leaf element compositions, spatial distributions and phylogeny of all species of Geissois occurring on New Caledonia. We found that New Caledonian Geissois descended from a single colonist and diversified relatively quickly into 13 species. Species on ultramafic and nonultramafic substrates showed contrasting patterns of leaf element composition and range overlap. Those on nonultramafic substrates were largely sympatric but had distinct leaf element compositions. By contrast, species on ultramafic substrates showed similar leaf element composition, but occurred in many cases exclusively in allopatry. Further, earlier work showed that at least three out of these seven species use different molecules to bind Ni. Geissois qualifies as a cryptic adaptive radiation, and may be the first such example in a lineage of tropical forest trees. Variation in biochemical strategies for coping with both typical and adverse soil conditions may help to explain the diversification and coexistence of tropical forest trees on similar soil types.

Two new species of Cunonia (Cunoniaceae) from New Caledonia

SummaryDescriptions, illustrations, distribution maps and conservation assessments are provided for two new species of Cunonia from New Caledonia. Cunonia dickisonii Pillon & H. C. Hopkins is endemic to montane ultramafic scrub at high elevation on Mts Humboldt and Kouakoué. Cunonia koghicola H. C. Hopkins, J. Bradford & Pillon is from wet forest at low to medium elevation in the region of Mt Koghi, and irregularities in leaf shape and venation suggest it may be of hybrid origin. Microendemism on Mt Humboldt and Mt Kouakoué is briefly discussed.

A Molecular and Morphological Survey of Generic Limits of Acsmithia and Spiraeanthemum (Cunoniaceae)

Abstract A phylogenetic analysis was conducted on the tribe Spiraeanthemeae (Cunoniaceae) to clarify relationships of Acsmithia and Spiraeanthemum. Three molecular markers, one plastid region (trnL intron and trnL-trnF intergenic spacer) and two nuclear single copy genes (ncpGS and PHYC), were sequenced for this purpose. The independent analysis of the three markers and a combined analysis all showed that Acsmithia is paraphyletic since Spiraeanthemum is nested within it. A morphological survey of all species in the tribe confirmed the existence of two groups within Acsmithia. One comprises the species from Australia, New Guinea, and A. densiflora from New Caledonia and is characterised by multiple ovules per carpel. The other group contains all the remaining New Caledonian species plus A. vitiensis from Fiji and is characterized by a single ovule per carpel. The study shows that characters previously used to distinguish Acsmithia and Spiraenthemum, phyllotaxy and sexual system, are homoplasious as in several other groups of Cunoniaceae. A broad circumscription of the genus Spiraeanthemum is adopted here that includes the species formerly placed in Acsmithia. Two new combinations are proposed: Spiraeanthemum collinum and Spiraeanthemum meridionale. Spiraeanthemum austrocaledonicum is considered a synonym of Spiraeanthemum densiflorum.

Nomenclature and typification of names in the endemic genus Pancheria (Cunoniaceae) from New Caledonia

Hopkins H. C. F. & Bradford J. C. — Nomenclature and typification of names in the endemic genus Pancheria (Cunoniaceae) from New Caledonia. Adansonia, sér. 3, 31 (1): 103-135. ABSTRACT The taxonomic history of Pancheria Brongn. & Gris is described and problems concerning types, including some collected by Montrouzier, Labillardière and Vieillard, are discussed. All names validly published in Pancheria or published under other generic names but referable to Pancheria are reviewed to establish their correct orthography and authorship, and they are lectotypified where necessary. Invalidly published names are dealt with briefly. The names P. humboldtiana Guillaumin ex H.C.Hopkins & J.Bradford, sp. nov., and P. multijuga Guillaumin ex H.C.Hopkins & J.Bradford, sp. nov., are validated by the designation of holotypes. An index lists all names referable to Pancheria and indicates their synonymy. The geographical position of Balansas collecting locality Mt Mi is discussed.

The endemic genus Pancheria (Cunoniaceae) in New Caledonia: notes on morphology and the description of three new species

SummaryA generic description of the dioecious genus Pancheria (Cunoniaceae) from New Caledonia is accompanied by notes on the morphology of the leaves, stipules, inflorescences, flowers and fruits. Descriptions, illustrations, distribution maps and conservation assessments are provided for each of three new species. Pancheria mcphersonii occurs on Mts Panié, Colnett and Ignambi in north-eastern Grande Terre, in dense low forest and montane scrub on soils derived from mica-schist (non-ultramafic). Pancheria dognyensis grows on the Plateau de Dogny in central New Caledonia and on Roche Ouaïème and Mt Mandjélia in the north-east, in forest and especially at the forest edge, also on non-ultramafic substrates. Pancheria ajiearoana is found in central Grande Terre, in scrub on ultramafic soils. Because all three species are restricted to a small number of areas at high elevation, climate change is one of the threats that justifies giving each of them a preliminary conservation status of Endangered; as global temperatures increase, the area of habitat with a microclimate suitable for these species is likely to decrease.

Further new endemic taxa of Cunoniaceae from New Caledonia

SummaryA description, illustration, distribution map and conservation assessment are given for each of three new species of Cunoniaceae from New Caledonia and plants endemic to the same localities from other genera are mentioned. Cunonia bopopensis Pillon & H. C. Hopkins is known from forest on ultramafic soils at high elevation on Mt Tchingou. This massif offers ecological conditions markedly different from those of its surroundings, which may explain the occurrence of several micro-endemics on this mountain. Some specimens of C. bopopensis were previously identified as C. bernieri Guillaumin but the type of the latter is probably a hybrid and this name is now considered doubtful. Geissois belema Pillon & H. C. Hopkins is endemic to Ile Art in the Belep archipelago, where it occurs in forest on ultramafic soils; it is the only species of Geissois known from Ile Art. Pancheria xaragurensis H. C. Hopkins & Pillon is found largely on the little-explored Forgotten Coast (“Côte Oubliée”) of south-eastern Grande Terre, generally in maquis along streams and in river beds at low elevation on ultramafic substrate. Morphological and ecological variation in the widespread taxa Geissois pruinosa Brongn. & Gris and Weinmannia dichotoma Brongn. & Gris are discussed and the combinations G. pruinosa var. intermedia (Vieill. ex Pamp.) H. C. Hopkins & Pillon and W. dichotoma var. monticola (Däniker) H. C. Hopkins & Pillon are published to accommodate some of this variability.

Jaffrea, a new genus of Rhamnaceae endemic to New Caledonia, with notes on Alphitonia and Emmenosperma

SummaryMolecular phylogenetic and morphological data show that two species of Rhamnaceae endemic to New Caledonia, Alphitonia xerocarpa and A. erubescens, are misplaced. They form a clade that is sister to Emmenosperma, and they differ from Alphitonia s.s. in their indumentum, venation, lower leaf surface, flowers, fruits and seeds. Although morphologically closer to Emmenosperma, both their flowers and fruits are distinct from those of Emmenosperma s.s., and so a new genus, Jaffrea H. C. Hopkins & Pillon, is described to accommodate them, and the combinations Jaffrea xerocarpa (Baill.) H. C. Hopkins & Pillon and Jaffrea erubescens (Baill.) H. C. Hopkins & Pillon are published. Members of this new genus have a conical hypanthium, petals somewhat incurved at anthesis, a thick disc that is either ± lumpy or annular but not or only partly covering the semi-inferior ovary, and fruits that are ovoid-ellipsoid, strongly beaked and tardily dehiscent. As in Emmenosperma and most species of Alphitonia, the seeds in Jaffrea can remain attached to the base of the fruit after most of the pericarp has fallen. Alphitonia is now represented in New Caledonia by a single species, A. neocaledonica, and its nomenclature and types are reviewed. The generic description of Alphitonia is amended to include the unique fruits of the New Guinean endemic A. macrocarpa, which are much larger than those of its congeners, strongly beaked, lacking a mealy endocarp, and with seeds that fall before the persistent valves. Relationships within Emmenosperma s.l., especially the affinities of E. papuanum and E. micropetalum, require further investigation.

Floral biology of the Cunoniaceae in New Caledonia and the role of insects, birds and geckos as potential pollinators

SummaryCunoniaceae are represented in New Caledonia by some 90 species, all of them endemic, and the family is thus a significant element in this diverse island flora. We present a descriptive survey of floral biology for the seven genera present, covering floral structure and colour, inflorescence shape, sexual system and phenology, plus details of floral visitors, where known, based on field observations; individual records of potential pollinators are tabulated in appendices. The flowers are polysymmetric (or almost so) and provide nectar and/or pollen as floral rewards. Two genera are dioecious and some species are mass flowering. Generalist entomophily is associated with several floral syndromes although the introduction of Apis mellifera has partially obscured historic relationships between some Cunoniaceae and their insect-pollinators. Codia and Pancheria both have sweetly scented, often creamish, spherical capitula and their floral visitors include honey bees, beetles, flies and native bees, especially halictids. Spiraeanthemum and Hooglandia have small, often whitish flowers in paniculate inflorescences but data on potential pollinators are few. Racemes occur in Weinmannia (flowers white, apparently scentless) and Cunonia p.p. (flowers white, pink or reddish with a faint foetid odour); visitors are mostly honey bees, plus ants, butterflies and native bees, and occasionally birds in the case of two reddish-flowered species. Ornithophily occurs in Geissois (flowers red, scentless, in bottle-brush racemes) and Cunonia macrophylla (flowers yellow-green, in one-sided racemes); their floral visitors are commonly Meliphagidae plus some Psittacidae and Zosteropidae. Pteropodid bats are also occasional visitors to Geissois. Geckos have been reported as flower-visitors in two genera though their contribution to pollen transfer is likely to be sporadic at most. Topics that require further investigation include some details of floral biology and the floral cycle, and the possible adaptive significance of different inflorescence shapes. Unanswered questions include: What visits taxa with paniculate inflorescences?, and for all genera: Which types of floral visitor are the most efficient pollinators? For the family as a whole, generalist entomophily appears to be the ancestral mode of pollen transfer and morphological specialisations to ornithophily have occurred independently in two groups of species and possibly in a third. Our data on birds and geckos agree with a known trend for these types of floral visitation and pollination to be well developed on islands, and flower-visiting by lizards in New Caledonia is likely to be more common than has been documented so far, both in Cunoniaceae and in the flora as a whole.