A Guide to Hoya of New Guinea

RM150.00

Book Summary

This comprehensive illustrated guide documents all species of Hoya (wax flowers) occurring in New Guinea. The guide includes detailed information on 72 taxa (67 species and five subspecies), featuring the most up-to-date account of the genus in this region until a comprehensive revision can be completed. With exceptional photography and detailed botanical descriptions, it serves as both a scientific reference and a practical guide to one of the world’s most biodiverse regions for Hoya species.

What the Guide Includes

Detailed species descriptions and identification guides for 72 Hoya taxa (67 species and 5 subspecies)
Comprehensive botanical illustrations and flower photography
Information on endemic species unique to New Guinea (86% endemism rate)
Ecological niche distribution across four elevation ranges (0–2600 m)
Habitat descriptions and conservation status assessments
Detailed fieldwork documentation from remote regions of Papua New Guinea and Indonesian New Guinea
Historical context of Hoya research and exploration in New Guinea since 1830
Systematics and phylogenetic relationships within the genus

Featured Species & Genera

Hoya coronaria complex (widespread from southern Thailand to Melanesia)
Hoya australis (most widespread species, spanning from Borneo to Polynesia with three subspecies in New Guinea)
Hoya nicholsoniae (reaching Polynesia and New Caledonia)
Papuahoya (segregate genus endemic to New Guinea, including P. urniflora and P. bykulleana)
Montane endemics: Hoya krusenstierniana, H. magnifica, H. juhoneweana ssp. lindforsiana
Lowland specialists: Hoya globulifera, H. archboldiana, H. ischnopus
Rare species: Hoya inflata (urceolate-globose corolla, recently rediscovered)

Authors and Publisher

Authors: Nadhanielle Simonsson and Michele Rodda
Publisher: Natural History Publications (Borneo) Sdn Bhd
Based on: Intensive fieldwork across Papua New Guinea and Indonesian New Guinea
Living collections established: Ukarumpa (1500 m highland collection) and Lae (lowland collection)
Collection partnerships: Singapore Botanic Gardens and Lae Botanic Garden (plants gifted 2017)

Who This Guide Is For

Hoya enthusiasts, collectors, and horticulturists
Botanists and naturalists studying New Guinean flora
Researchers focused on tropical plant diversity, endemism, and evolution
Plant photographers and field naturalists
Conservation professionals and biodiversity advocates
Herbarium curators and taxonomic specialists
Anyone interested in New Guinea’s unique natural heritage

Ecological Zones & Habitats

Lowland to lower montane (0–1000 m): Most species-rich zone, comprising approximately 70% of all New Guinean Hoya species
Hill forest (1000–1500 m): Fewer species recorded, but almost all endemic to New Guinea (e.g., H. juhoneweana ssp. lindforsiana)
Cloud forest (1500–2000 m): Even fewer species, virtually all endemic; cool montane specialists like H. edholmiana and H. magnifica
Mossy alpine forest (2000–2600 m): Only Hoya krusenstierniana (including ssp. laticorolla) and H. venusta recorded
Savannah woodlands: Semi-arid adapted species in Trans-Fly region (southern New Guinea)
Habitat types: Epiphytic (majority), terrestrial, hemi-epiphytic, and moss-covered habitats across all zones

Corolla Diversity & Flower Characteristics

Eight corolla types documented: rotate, campanulate, reflexed, reflexed with revolute lobes, inflexed, urceolate-globose, salverform, and tubular
New Guinea specimens display seven of eight types (tubular absent)
Hoya versteegii (endemic to New Guinea) and H. telosmoides (Borneo) are the only two species with salverform corollas
Predominantly two colour patterns: white flowers with white or crimson coronas; creamy yellow, pink, or wine-red with matching coronas
Flower size ranges from 2.5–3 cm (tiny species like H. pulchella and H. oligantha) to over 4 cm in 13 campanulate species
Corolla shapes correlate with ecological niche and light exposure

Endemism & Biogeography

86% endemic taxa: Of 72 taxa, only 10 are found elsewhere; 62 taxa endemic to New Guinea and Bismarck Archipelago
Highest endemism rate in region: 50% of Hoya species in Borneo are endemic by comparison
Widespread species (8 non-endemic): H. anulata, H. australis, H. coronaria, H. globulifera, H. inconspicua, H. ischnopus, H. nicholsoniae, and H. subglabra
Hoya australis spans from Borneo to Polynesia and Australia (widest distribution)
Hoya inconspicua extends to Melanesia; H. ischnopus recently found in Sulawesi
Papuahoya species entirely New Guinea endemic

Conservation Status & Threats

Vulnerable species: 65 of 72 taxa (90%) are endemic with restricted ranges, facing high extinction risk
Not vulnerable: Only 8 adaptable, widespread species (H. anulata, H. australis, H. coronaria, H. globulifera, H. inconspicua, H. ischnopus, H. nicholsoniae, H. subglabra)
Data Deficient: Many species documented only from decades-old herbarium specimens with no recent field records
Primary threats: Logging, conversion to oil palm plantations, uncontrolled bushfires from slash-and-burn agriculture
Protected areas: Indonesian New Guinea has ~20% land protection; Papua New Guinea has only ~4%
Positive factor: Hoya easily propagated from cuttings; minimal horticultural collection pressure on wild populations
Example of extinction risk: Hoya inflata (last wild collection 1992, believed extinct until Indonesian rediscovery)

Fieldwork Challenges & Methodology

Access difficulties: Inaccessible primary forests, limited road infrastructure, mountainous terrain up to 4,884 m (Puncak Jaya)
Transportation: Small aircraft, dugout canoes, and multi-day hikes required to reach remote villages
Critical discovery: Field data showed only 1 in 300 sighted Hoya plants in flower (vs. wild-collected herbarium specimens representing only flowering individuals)
Implication: Herbarium specimens vastly underrepresent actual species diversity
Living collections solution: Two collections established (2010) in Papua New Guinea to grow non-flowering specimens to flowering stage for study
Permission protocols: Forests privately owned by villages in PNG; permission required from village Chief following 800+ distinct cultural traditions

Why This Guide Matters

New Guinea hosts exceptional plant diversity with 86% of Hoya taxa endemic to the region
Represents the most comprehensive account of the genus in this biogeographic area
Documents species from challenging and remote fieldwork across two countries (Papua New Guinea and Indonesian New Guinea)
Addresses urgent conservation needs as primary forests face logging and conversion at accelerating rates
Preserves critical knowledge of species that may face extinction before any comprehensive revision is possible
Establishes baseline data through living collections in botanical gardens for ex-situ conservation
Celebrates Hoya‘s remarkable morphological diversity: eight corolla types, variable leaf sizes (1 mm to 20+ cm), and striking colour patterns
Fills significant gaps left by herbarium specimens that represent only ~0.3% of actual wild populations