Aqua Planta 35,1 (2010): 23-28
Habitat of Cryptocoryne dewitii in Papua New Guinea
Takashige Idei Osaka JAPAN

Abstract
Cryptocoryne dewitii was discovered in 1971 in the Western province of Papua New Guinea by Mr. Paul Katik from the Division of Botany at Lae, and it has not been recorded since then. This investigation was carried out in July 2009 based on the data from the original collection from the Kiunga area and the habitat report is presented. Cryptocoryne dewitii is named in honour of professor H.C.D. de Wit, who was leader of the Cryptocoryne studies in those days. The other Cryptocoryne species known from New Guinea are Cryptocoryne versteegii Engler and Cryptocoryne ciliata (Roxb.) Schott.

Introduction
Kiunga is located in the midstream part of the Fly River which is the longest river in Papua New Guinea. The headwater is the Central Range, and it flows southwards through the wetland forests into the Gulf of Papua, and has a total length of 1050 km. Kiunga is located in tropical rainforest climate zone. The average yearly air temperature is around 26 °C. The annual rainfall reaches up to 8000 mm, and in the month of August it decreases relatively, and reaches a short lasting minimum in September. There is a typical tropical rain forest climate due to the remains of the immense primeval forest remaining.

The investigation site
The habitat of Cryptocoryne dewitii is a small-scale marsh that adjoins the swamp forest of Kiunga, and it is located at a slightly higher level than the swamp forest. The general altitude of the area is less than 40 m. The habitat of C. dewitii is less than one m above the Fly River wetland forest area at Kiunga.

There is a Sago Palm (Metroxylon sagu Rottb.) canopy cover that provides some diffusion of sunlight to the vegetation below, and the surface of the riverbed is almost covered with fallen leaves of Sago Palms. Various juvenile Araceae (probably Schismatoglottis sp.) surrounded the C. dewitii habitat. Barclaya motleyi Hook.f. is coexisting with Cryptocoryne dewitii but growing in somewhat deeper water.

This swamp consists of a peat layer that has accumulated from fallen leaves to a depth of more than 1m in depth above the laterite soil base. The very low water level change is, during the drier period, influenced more by the local rainfall and by the rise from the subterranean water, rather than by the water level changes of the Fly River. There is a small water seepage of a very slow flow which at least partly appears to be due to the oozing of the subterranean water. The water colour is transparent brown as it contains a high iron content of 1.5 mg/l. The water temperature is stable around 26°C. A pH of 6.0 shows that the surface layer is rainwater and that it is from the inside of the peat layer. Dissolved Oxygen (DO) is 3.1mg/l, and the Chemical Oxygen Demand (COD) of more than 8 mg/l shows the comparatively fast consumption of oxygen by the peat layer. Calcium is 5 mg/l and Magnesium was not detected.

Cryptocoryne dewitii N. Jacobsen
Cryptocoryne dewitii grows under emerged conditions in dense stands at a high humidity community that depends on a rainfall almost every day. The leaf colour is generally green with slightly brown tinge on both sides and it is more or less bullate. As a characteristic of the species, the leaf margin of C. dewitii has like an irregularly denticulate appearance because of the somewhat finely undulated margin of the leaves; the leaf base is distinctly flattened, and the leaves have a comparatively thick petiole. Individual plants generally have less than 14 elliptic leaves, and some of narrow or round cordate leaves are about 1/3 to 4/5 in width compared to length in leaves. The form of the leaf shapes seems to relate to individual growth conditions of that time, i.e. submerged versus emergent. Leaf length is about 25 cm in the largest plants as the leaf blade is 13 cm long, and the petiole length 12 cm.

The diameter of the rhizome is up to 8 mm; the length is up to 7 cm. Roots are concentrated within upper part 4 cm of the rhizome, and iron sticks to the whole surface. The whole root system is growing within a depth of 15 cm generally by “hair-roots”. Runner multiplication is more often seen than seedlings.

The spathe of Cryptocoryne dewitii is from 6 to 11 cm long and there is some variation in the shape and colour. The colour of the limb is white to light tinted purple, and it is more or less backwards spirally twisted, and the broad collar zone is distinct reaching from 1/3 to 1/2 of the spathe limb length. It has many characteristic protrusions along the limb margin and limb surface. Both the inside wall and the outside of kettle and the tube are white. The largest spathe had a limb of 5 cm in length, the tube 2.5 cm long, kettle 1.5cm long with the diameter of 7 mm, and a 2 cm long peduncle. The spadix has 5 to 7 female flowers followed by a white sterile spadix axis and thereafter the ellipsoid, light yellow male part and ending in a dome shaped purplish appendix; the valve is long (longer than the male part if the spadix) and white. The white female flowers have a short style and a more or less rounded to elliptic stigma; the olfactory bodies above the female flowers are rounded and distinctly white coloured. The number of male flowers is more than 30. The lifespan of most of the spathes are within 2 days. The diameter of the infructescence is within 1cm.

Acknowledgements
Respect is expressed to Professor H.C.D. de Wit and Mr. Paul Katik, Lae (Papua New Guinea). I am grateful to Prof. Niels Jacobsen and Mr. Jan D. Bastmeijer, for their encouragements and comments on the manuscript. To Dr. Josef Bogner for the translation of the text into German.

References
Bastmeijer, J.D., 2009. http://www.xs4all.nl/~crypts/Cryptocoryne/index.html
Idei, T., 2009. De habitat van Cryptocoryne dewitii in de Western provincie van Papoea-Nieuw-Guinea. Het Aquarium 79(11): 29-31.
Jacobsen, N., 1977. Cryptocoryne dewitii N. Jacobsen sp. nov. (Araceae). Bot.Not. 130: 381-382.
Wit, H.C.D. de, 1983. Aquariumplanten, 4druk. Uitgeverij Hollandia, Baarn.
Wit, H.C.D. de, 1990. Aquarienpflanzen, 2Aufl. Eugen Ulmer Verlag, Stuttgart.

Legends
p. 23. The habitat of Cryptocoryne dewitii with Sago palms and the dead palm leaves on the bottom.
p. 24 top. The river system of the Fly river and the rainforest near Kiunga.
bottom. A big patch of Cryptocoryne dewitii on the forest floor with dead palm leaves.
p. 25 top. Cryptocoryne dewitii with Barclaya motley in seepage water with a high iron content. middle. Patch with Cryptocoryne dewitii apparently shortly after getting emerged, showing the cordate and bullate leaves. bottom. Patch with Cryptocoryne dewitii showing the more even and lanceolate leaves which have grown at emerged conditions. p. 26 top. Flowering Cryptocoryne dewitii with rather even, emerged leaves
bottom. A few flowering Cryptocoryne dewitii from the natural site. p. 27. Flowering Cryptocoryne dewitii.
p. 28 top. Opened kettle of Cryptocoryne dewitii; showing the female flowers at the bottom, from there the naked spadix and in top the male flowers and the purple coloured appendix. Left from the male flowers and the appendix the relative long valve. Photo: J.D. Bastmeijer bottom. Professor Dr. N. Jacobsen (left) and professor Dr. H.C.D. de Wit (right) to whom the species is named. Photo: C. Kasselmann

All photos Takashige Idei, unless otherwise stated.