Geophila erythrocarpa ( Rubiaceae ) , a new species from d . r . congo and Zambia

Geophila D.Don is a pantropical genus of creeping herbs and is a typical element of the forest floor in tropical regions. Geophila species often form dense mats, sometimes decorated with white flowers or red, blue or black coloured fruits. The genus belongs to the tribe Palicoureeae of the Rubiaceae family (Robbrecht & Manen 2006). Palicoureeae was recently separated from the Psychotrieae and includes eight to ten genera depending on generic delimitations. This pantropical tribe has it highest species diversity in the neotropics and is characterized by the combination of solitary anatropous ovules that are attached at the base of the locules, valvate aestivation of the corolla lobes, fleshy drupes, pyrenes with distinct preformed germinations slits and very reduced, pale seed-coats (Robbrecht & Manen 2006). Geophila and Hymenocoleus Robbr. are the only genera of the tribe with a predominantly herbaceous habit. Geophila differs from the African genus Hymenocoleus in the absence of a membranous sheath at the inside of the stipules and by the pyrenes ribbed at the dorsal side (Robbrecht 1975). An additional distinguishing character is found in the fruit colour: Hymenocoleus fruits are orange while those of Geophila are red or blue to black, but never orange.


IntroductIon
Geophila D.Don is a pantropical genus of creeping herbs and is a typical element of the forest floor in tropical regions.Geophila species often form dense mats, sometimes decorated with white flowers or red, blue or black coloured fruits.The genus belongs to the tribe Palicoureeae of the Rubiaceae family (Robbrecht & Manen 2006).Palicoureeae was recently separated from the Psychotrieae and includes eight to ten genera depending on generic delimitations.This pantropical tribe has it highest species diversity in the neotropics and is characterized by the combination of solitary anatropous ovules that are attached at the base of the locules, valvate aestivation of the corolla lobes, fleshy drupes, pyrenes with distinct preformed germinations slits and very reduced, pale seed-coats (Robbrecht & Manen 2006).Geophila and Hymenocoleus Robbr.are the only genera of the tribe with a predominantly herbaceous habit.Geophila differs from the African genus Hymenocoleus in the absence of a membranous sheath at the inside of the stipules and by the pyrenes ribbed at the dorsal side (Robbrecht 1975).An additional distinguishing character is found in the fruit colour: Hymenocoleus fruits are orange while those of Geophila are red or blue to black, but never orange.
The second author reviewed the paleotropical species of the genus to obtain the degree of Master in Biology and discovered Geophila material in BR that could be matched with the Fanshawe 6855 specimen from Zambia referred to Geophila sp.A in Flora Zambesiaca (Verdcourt 1989).The additional specimens now allow the formal description of this taxon as Geophila erythrocarpa Vanthournout & Dessein.

MaterIal and Methods
Herbarium material of Geophila was consulted at BR, HBG, K, MO and WAG.Descriptive terminology for simple symmetrical plane shapes follows Anonymous (1962).Phytogeographical considerations follow White (1979White ( , 1983)).
To estimate the conservation status of the species, geo-referenced specimen data were imported into ArcView™ geographic information software to generate the distribution map and to calculate area of occupancy (AOO) and extent of occurrence (EOO) using Cats 1.2 (Moat 2007).The cell area was set to the largest permissible value (cell width = 3.16 km).The AOO and EOO figures were used in conjunction with Google Earth observations and literature data to produce a conservation rating based on the IUCN Red List Categories criteria (IUCN 2001).Vanthournout & Dessein, sp. nov.-Fig. 1 Affinis  Verdcourt (1989).

Geophila erythrocarpa
Etymology.The epithet 'erythrocarpa' refers to the red colour of the fruits, which is the most important character to distinguish the species from G. obvallata.
Creeping herb with underground stems rooting at the nodes; stems densely pubescent; leafy and flowering shoots reaching a height of 4-5 cm.Leaves opposite; petiole 1.5-7 cm long, pubescent all around; blades broadly ovate to circular, 1.5-6.7 by 1.5-7.5 cm, sparsely pubescent above and underneath, rounded at the apex, cordate at the base; venation not very prominent with 3-5 secondary veins at each side of mid-vein and a fine reticulate network of tertiary and quarterly veins.elliptic to triangular, 2-3 by 3-5 mm, glabrous.Flowers 5-merous, presumably isostylous, 2 -3 per inflorescence; peduncle 0.5-5 cm, densely hairy; involucre consisting of two unequal pair of bracts, the outer bracts broader and slightly to strongly bilobed, the inner ones narrowly elliptic and entire; involucral bracts free to variously connate to each other at the base, 7-9 mm long, hairy outside and inside, beset with colleters at the base inside; bracteoles, if present, somewhat spathulate.Calyx tube 1-2 mm, glabrous or with a few hairs near the margin, truncate.Corolla white; tube cylindrical, c. 5 mm long, sparsely hairy outside, with a band of hairs at and just above the insertion point of the anthers inside; throat appearing glabrous viewed from outside; lobes elliptic, c. 2 mm long, sparsely hairy outside, glabrous inside.Anthers narrowly elliptic, c. 1.4 mm long, attached somewhat below the middle of the corolla tube; filaments very short.Ovary 1-1.5 mm; style c. 1.3 mm long, included in the corolla tube, positioned below the anthers; stigma shortly bilobed.Drupes red, globose, 7-9 mm, sparsely pubescent; pyrenes light brown, elliptic, 3.5 -5 by 3 -4 mm, bony; dorsal surface with 3 -4 dorsal ribs, verrucate to rugose in between the ribs; ventral surface with 2 ventral grooves.
Distribution -Occurring in the Zambezian Regional Centre of Endemism and there restricted to the Katanga Province of D.R.Congo and the adjacent Copperbelt Province of Zambia.
Vernacular name -Kontumba Tumba (dial.Kisanga; Nassogne 89).Conservation status -Based on the limited area of occupancy the Endangered threshold is met (AOO = 79.88 km 2 ), whereas the Vulnerable threshold is met based on the extent of occurrence (EOO = 18,005 km 2 ).The ecology of the species is dry evergreen forest, often named 'muhulu' in D.R.Congo (Bamps 1975).Muhulu is sometimes described as the climax vegetation of Katanga and other areas of the Zambezian Regional Centre of Endemism with a similar climate (Schmitz 1950(Schmitz , 1962)).Muhulu forest is now found in relatively small patches and is easily degraded by human activities such as wood exploitation and fire management.In this context it is noteworthy that the Njiri forest reserve in Zambia, where G. erythrocarpa was apparently very common, has been degazetted and that the land has been allocated to squatters.Based on the small number of locations, the patchy occurrence of dry evergreen forest in the area, and the continuous decline of the extent and quality of habitat, G. erythrocarpa qualifies for Endangered under criterion B (EN B2ab(iii)).

dIscussIon
The delimitation and subsequent identification of Geophila species is notoriously difficult (Piesschaert et al. 1999a, b), especially when based on herbarium specimens only.There are, however, a number of characters that are fairly stable at species level, i.e. stipule morphology, pubescence pattern on the petioles, pubescence pattern on the inside of the corolla tube, fruit colour and pyrene morphology.Pollen also provides useful taxonomic data, but pollen studies in Geophila are often hampered by lack of suitable flowering material (Piesschaert et al. 1999a) and are of course of little use for routine determinations.
In general appearance, the new species resembles G. obvallata, a species distributed from Guinea Bissau to Angola, over D.R.Congo, Sudan, and C.A.R., to eastern Kenya and Tanzania and Mozambique.It is a very variable species with three recognized subspecies with partly overlapping distributions (Verdcourt 1989).Geophila erythrocarpa is most similar to G. obvallata subsp.ioides (K.Schum.)Verdc.and the distribution of the two taxa partially overlaps in Katanga (D.R.Congo) and the Copperbelt (Zambia).The leaf shape and stipule morphology of the two taxa is very alike which gives them a very similar facies in the dry state.Fruit colour (deep blue in G. obvallata vs red in G. erythrocarpa), hair pattern on the petiole (in two rows in G. obvallata vs all-around in G. erythrocarpa), calyx morphology (deeply lobed in G. obvallata vs truncate in G. erythrocarpa), shape of the involucral bracts (entire in G. obvallata vs deeply lobed in G. erythrocarpa), and hair pattern of the corolla tube (hairy above insertion of anthers up to corolla lobes in G. obvallata vs hairy zone limited to area around insertion point of anthers in G. erythrocarpa) distinguish the two species (Table 1).
Geophila erythrocarpa also shows similarities with G. afzelii, especially in calyx and corolla morphology (Table 1).The pyrenes are also similar, but those of G. erythrocarpa are dorsally clearly verrucate to rugose in between the ribs, while those of G. afzelii appear smooth in between the ribs under low magnification.A more distinct difference, easily observed in the field, is found in the stipules, which are bifid in G. afzelii and entire in G. erythrocarpa.Unfortunately this character is often difficult to determine on dry material.Leaves of G. afzelii often show a redpurple coloration of the lower surface of the leaves, visible both in living and dry plants, a character absent in G. erythrocarpa.Other differences are found in the number of flowers per involucre (many in G. afzelii, few in G. erythrocarpa) and the involucral bracts (numerous and usually entire, sometimes shortly lobed in G. afzelii vs two 2-lobed and two narrowly elliptic bracts in G. erythrocarpa).Geophila afzelii is essentially a Guineo-Congolian species and is absent from the Zambezian Regional Centre of Endemism.
Geophila erythrocarpa is also easily separated from a third species occurring in the region, G. repens, which is a species with inflorescences without involucre.
Five other species are reported from D.R.Congo.Geophila renaris differs in the reniform leaves, the bifid stipules, and the 3-lobed bracts, G. ingens in the two rows of hairs on the petiole, the bifid stipules, the many-flowered inflorescences, the deeply lobed calyx and the pyrene morphology, and G. lancistipula in the two rows of hairs on the petiole, the bifid stipules, the absence of an involucre, the blue flowers and the pyrene morphology (Table 1).The two other species reported from D.R.Congo, i.e.G. obtusifolia K.Krause and G. aschersoniana Büttner should be reduced to synonymy under G. renaris and G. obvallata respectively.
Geophila obtusifolia K. Krause (1911), syn.nov.-Type: Mildbraed 3285 (B, not found; BR, fragm.),Aruwimi (D.R.Congo).The type specimen in B could not be found, but a fragment of this specimen was found in BR.It clearly shows that it is identical to G. renaris, described in 1899.
Geophila aschersoniana Büttner (1889), syn.nov.-Type: Büttner 147 (B, not found), between Bolobo and Lukolela (D.R.Congo).The type specimen in B could not be found and was probably destroyed.Its description, however, allows us to reduce the species to G. obvallata.According to Büttner, G. aschersoniana differs from G. obvallata in the presence of inner involucral bracts, which he describes as narrower and often incised at the apex.The involucral bracts of G. obvallata are somewhat variable and the description of the bracts of G. aschersoniana well falls within the observed bractal variation of G. obvallata.
acknowledgements Petra De Block and Olivier Lachenaud are thanked for checking the Geophila material of K and for their useful comments.We acknowledge two anonymous reviewers for critically reviewing an earlier version of the manuscript.Marijke Meersman is thanked for the botanical illustration.

Stipules
fig. 1 Geophila erythrocarpa Vanthournout & Dessein.a. Habit; b. infructescence; c. detail of involucre seen from above with position of fruit indicated in stippled line; one bracteole inside involucre; d. detail of leaf base and petiole; e. ovary with persistent calyx; f. opened corolla showing position of anthers and style; the line on the right indicates the occurrence of trichomes inside the corolla tube; g. detail of style; h.dorsal (left) and ventral (right) view of the pyrenes; i. transverse section through pyrene (a -d: Schmitz 2303, BR; e, h, i: Malaisse & Goetghebeur 1032, BR; f, g: Kassner 3545, HBG).
around Hairs above insertion point Zone of hairs around Hairs above insertion point Zone of hairs around Glabrous insertion point anthers; insertion point anthers; of anthers to base of lobes; insertion point anthers; of anthers to base of lobes; insertion point anthers; Key morphological characters and distribution of the Geophila species now recognized from D.R.Congo and Zambia.

Geophila erythrocarpa (Rubiaceae), a new species from d.r.congo and Zambia Geophila
sp. A,