A newly described species from Goodenough Island, Papua New Guinea
The northernmost citrus species endemic to Australia is Citrus gracilis. Named and first botanically described by Mabberley in 1988, it grows in the Darwin region of Australia's Northern Territory.
Port Moresby in Papua New Guinea lies approximately 150 Kms from mainland Australia and is home to Citrus wintersii (formerly Microcitrus papuana), first described in 1976. It grows in the Brown River region inland from Port Moresby.
The home of Citrus warburgiana (formerly Microcitrus warburgiana) is further south-east along the coast of Papua New Guinea.
Still further from the tip of Australia - some 800 Kms - is Goodenough Island. In the 1950's, the noted botanist and plant collector L.J.Brass reported finding citrus species on the island. They were assumed to be another population of Citrus warburgiana.
The specimen in the Canberra Herbarium is described as:
Slender tree 3 m tall; fruits (unripe) yellowish green. Collected by L.J. Brass on the 4th Archbold Expedition to New Guinea (March-November 1953).
Mabberley's 1988 article on Australian Citreae is available here
In September 2000, Malcolm Smith of Bundaberg Research Station (Queensland's Department of Agriculture, Fisheries and Forestry) visited Goodenough Island in Papua New Guinea and re-located the citrus trees first reported by Brass. Details were published in Austrobaileya and the article is available for download here. Working together with Paul Forster, he showed that these were a new and undescribed citrus species differing from Citrus warburgiana in several respects.
The illustrations above are a re-arrangement of the drawings of Citrus wakonai published in Austrobaileya 8(2): 133-138 (2010). PDF version available for download here.
Citrus tristeza virus (CTV) is an economically important disease of citrus that is found worldwide. Researchers at Bundaberg are working on producing improved rootstocks for commercial citrus, with the particular aim to remove any susceptability to CTV, before introducing other useful characteristics. Citrus wakonai is helpful in hybridisation studies because, unlike most citrus, it flowers and fruits in its first year from seed. Research has focussed on crossing C. wakonai with C. glauca (the Australian Desert Lime), and further crossing with Poncirus trifoliata; as well as C. wakonai with the African citrus relative Citropsis gabunensis.
Even the entry in Brisbane Herbarium fails to reveal the exact co-ordinates. It says:
Small tree up to 6m tall. Bark corky, cream; foliage glossy, dark green above, paler below; flowers white; fruit obovoid, surface rough, irregular, yellow-green when mature; flesh dull, pale yellow. Very common at locality of collection and from where the seed for this cultivation were taken.
From BingMaps an aerial view of the roadless Wakonai village.
Finally, after much research, I found the exact location of Wakonai via the German version of Wikipedia, see details here.
The Austrobaileya article says the local name for the fruits of C. wakonai is kamokuku. The local language for this very remote area is called Iduna. Interestingly, I found an Iduna-English dictionary in which the word for a lemon is also listed as kamokuku.
Fruit of Citrus wakonai
This information poster was produced for The International Citrus Congress, Valencia, Spain 2012. It covers some of the Queensland rootstock research using Citrus wakonai
Full size poster here
This new species was named Citrus wakonai - 'Wakonai' being the village nearest the citrus trees. However, I have had great difficulty locating any map showing a village with this name.
With thanks to Malcolm Smith, Bundaberg Research Station, Queensland, Australia who provided information and images for this page.
Fancy a trip to Wakonai? Read this account first!
Flowering twig of Citrus wakonai growing at Bundaberg Research Station
Click photo above for bigger version
The native vegetation found on Goodenough Island varies from open savannah-like grassland to dense forest. The black & white photo above is a view of Wakonai village taken during the 1954 Archbold Expedition. The war-time Vivigani airstrip is just visible near the top of the picture.
The lower colour photo, taken in 2000, shows a plant of Citrus wakonai in its native habitat.
page created 8th January 2014
Do you have any more information on Citrus wakonai?
In part as a result of reading this page, intrepid Frenchman Sylvain, set off in August 2014 to find Citrus wakonai. Read all about his adventures in
The Quest for Wakonai!