Trichoscypha
Creators: name: Breteler, F. J.
Publisher: name: Zenodo
Year: 2004
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Sapindales
Anacardiaceae
Trichoscypha

description: CHARACTERS OF THE GENUS TRICHOSCYPHA
Trees, sometimes large (≥ 40 m), mostly small and slender, branched or not, shrubs, or lianas. Exudate little, white to orange-pink, black when dry. Leaves, imparipinnate, rarely simple, often crowded at the top of the trunk or end of branches. Inflorescence many-flowered, (sub)terminal or axillary, and/or borne below the leaves on the main stem or branches. Flowers unisexual, dioecious, rather small (≤ 8 mm), usually 4-merous often a few 5-merous ones, rarely 6-merous, sessile to pedicellate, the female flowers generally less numerous and often with longer pedicels than the male flowers. Sepals united at base, suberect. Petals free, usually imbricate (mostly narrowly so) or valvate in bud, ± erect, spreading, or reflexed at anthesis. Stamens the same in number as the petals and alternate with them, inflexed in bud. Disc present, glabrous or variously hairy, in the male flower sometimes surrounding a small pistillode, in the female flower located at the base of the ovary. Staminodes present in female flowers. Ovary glabrous to variously hairy, 1-locular, crowned by 3-4(-6) styles with entire to shallowly bilobed stigmas, or stigmas ± sessile, ovule one, pendulous. Fruit fleshly, 1-seeded, rarely dehiscent.
TYPE. — Trichoscypha mannii Hook.f.
MORPHOLOGICAL NOTES
Several species exhibit considerable variation in habit, from erect shrubs to lianas and usually to medium-sized trees. A few intermediates (described as “long very slender trees”) have been found and field notes sometimes indicate that an erect individual has been found close to a lianescent one of apparently the same species. The use of habit alone in identification keys, as was done by VAN DER VEKEN (1960), is therefore very unsatisfactory.
Within a species leaves can be extremely variable in the number, size and shape of their leaflets as well as in indumentum and the number of lateral nerves. Foliar characters are thus rarely of much use in separating species (see Fig. 9). Only the inflorescence, flowers and fruits offer taxonomically reliable characters.
Some species (e.g., Trichoscypha reygaertii and T. rubicunda) show a patchy, whitish indumentum on the leaves, inflorescences, and, sometimes on the fruits as well (T. rubicunda). This indumentum is intermediate in appearance between arachnoid hairs and fungal mycelium. Sometimes it is so dense that it appears normal hairs have difficulty coming through (see Fig. 14G, H).
Information on the indumentum of the calyx is provided in the discussion under T. bracteata.
Trichoscypha hallei and T. laxiflora are the only species from Lower Guinea and Congolia with truly valvate petals. In all the other species the petals are, at least in part, imbricate and mostly narrowly so. The valvate character of the petals in T. hallei and T. laxiflora is associated with the presence of minute, brown dots on the lower surface of the leaflets.
Most species with a hairy disc also have hairy ovaries. Exceptions are found in T. acuminata whose disc may be glabrous or hairy whereas the ovary is always hairy, and in T. hallei, T. oddonii, and T. rubicunda, in which a glabrous disc occurs in combination with a hairy ovary (see also BRETELER 2001: 248).
Seedlings of Trichoscypha bijuga, T. mannii, and T. patens have been grown at the Herbarium Vadense greenhouses in Wageningen. They all show the same model in which the germination is hypogeal, with the distinct epicotyle of 8-12 cm in length is terminated by two opposite, simple leaves. The next leaves are also simple, but usually have longer petioles, and may be considered as unifoliolate. The seedlings of T. oddonii, grown in Congo (Kinshasa), have an epicotyle 20-25 cm long, with the first pair of leaves also opposite but with long petioles and one to three leaflets.
GEOGRAPHICAL NOTES
Of the 18 species of Trichoscypha present in Lower Guinea and Congolia, 14 are endemic to this area; the remaining four species, T. arborea, T. bijuga, T. lucens, and T. mannii, also occur in Upper Guinea (BRETELER 2001). Trichoscypha lucens, which occurs from Liberia to Africa East coast, is the only wide-spread species. The 18 species treated here are very unevenly distributed over Lower Guinea and Congolia. Most of the diversity occurs in Lower Guinea where 17 species are present of which eight are endemic, whereas Congolia only has eight species, of which T. pauciflora is the only endemic. When considered on a country by country basis, Gabon, in the centre of Lower Guinea, is the richest with 16 species present, followed by Cameroun with 13 species. In Congo (Brazzaville) eight species occur and Congo (Kinshasa) has nine whereas Nigeria has seven. In Cabinda, the northern part of Angola, five species have been recorded. Much more exploration is however needed for a better understanding of the variation in habit and morphology as well as of the distribution of certain species (e.g., T. engong, T. hallei, T. oliveri), which show gaps in their ranges based on available material that almost surely represent an artefact of insufficient collecting, that are too wide to be true.
Key to the species of Trichoscypha in Lower Guinea and Congolia
The following key is based on material with male flowers unless stated otherwise. When known and when useful, characters of the female flower and/or fruit have been included.
The disc in the female flower is similar to that of the male flower. It remains observable, with or without hairs, in fruit.
1. Trees with inflorescences borne on the main stem and/or on the thicker branches .................................... 2
1’. Trees, shrubs, or lianas with (sub)terminal and/or axillary inflorescences and/or with inflorescences borne just below the leaves, when cauliflorous, then, as a rule, with axillary and/or (sub)terminal inflorescences also present .............................................................................................................................................. 6
2. Leaflets strongly asymmetric at base (see Fig. 7); lower surface covered by stellate hairs. Gabon ..............................................................................................................................................................5. T. debruijnii
2’. Leaflets not asymmetric at base or only slightly so; lower surface, if hairy, with simple hairs only .............. 3
3. Trees up to at least 35 m tall and 1 m dbh, with large crown. Inflorescences mainly on the thick branches, sometimes extending below these, i.e. on the upper part of the trunk as well; pistil glabrous. Cameroun, Equatorial Guinea, Gabon ........................................................................................................ 6. T. engong
3’. Slender trees, up to 25 m tall and 50 cm dbh, poorly branched or not, i.e. with narrow crown, or shrub up to 8 m tall; flowers borne on the trunk, usually well below the leaves, at most at 5 m height; pistil hairy or glabrous .................................................................................................................................................... 4
4. Inflorescence bracts up to 7 mm long; disc glabrous (Fig. 2E); ovary and fruit glabrous. Eastern Congo (Kinshasa)..........................................................................................................................16. T. pauciflora
4’. Inflorescence bracts at least 15 mm long; disc glabrous to sparsely hairy, ovary and fruit hairy .................. 5
5. Leaves up to 1.5 m long, 7-17(-22?)-jugate; leaflets usually glabrous beneath or nearly so, oblong-elliptic, sometimes laceolate, (6-)15-20(-28) × (2-)3-7(-10) cm, with (9-)12-18 pairs of main lateral nerves; disc sparsely hairy to glabrous (Fig. 1A); pistillode absent. Nigeria to Central African Republic, Congo (Kinshasa), and Angola ...................................................................................................... 1. T. acuminata
5’. Leaves 1.15-2.5 m long, (16-)22-28-jugate; leaflets usually distinctly hairy beneath, lanceolate-oblong, (13-) 20-35(-50) × (2.5-)7-10(-12) cm, with (10-)15-24(-34) pairs of main lateral nerves; disc glabrous, a hairy pistillode present or not (Fig. 2B). From Cameroun to western Congo (Kinshasa) and Angola (Cabinda)..................................................................................................................................................13. T. oddonii
6. Disc hairy ................................................................................................................................................ 7
6’. Disc glabrous or with a few hairs in the centre (i.e. on the pistillode) only .............................................. 11
7. Petiole deeply canaliculate above, the ± thin borders folded inwards (Fig. 11C); flowers with cucculate petals (Fig. 11A, B); ovary velutinous. SW Gabon .................................................................... 12. T. nyangensis
7’. Petiole ± flat to very shallowly canaliculate above, or grooved only, or (sub)terete; flowers without cucculate petals ........................................................................................................................................................ 8
8. Disc distinct, ± firm, well exposed, 1.5-2.5(-3) mm in diam., usually with appressed indumentum and with imprints of anthers (Fig. 2C); fruits pubescent, oblique, apiculate, laterally compressed, at least when immature. From Cameroun to Congo (Kinshasa) .................................................................. 14. T. oliveri
8’. Disc not apparent, merely looking like the velutinous to hispid bottom of the flower (Figs 1G, I; 2A), 0.5- 1 mm across, usually without imprints of anthers, or these hidden by the ± erect indumentum; fruits terete or elliptic in cross-section, usually not oblique, beaked or ± rounded at apex ............................................ 9
9. Stamens at most as long as the ± 1.5 mm long petals (Fig. 1G); fruit ellipsoid, sparsely appressed-puberulous. Coastal region of Gabon ............................................................................................ 8. T. imbricata
9’. Stamens longer than petals, the latter 2-4 mm long (Figs 1I; 2A) ............................................................ 10
10. Anthers ≥ 1mm long; petals (2.5-) 3-5 mm long; fruit usually beaked, at least sparsely hairy. Nigeria to Congo (Brazzaville) .............................................................................................................. 11. T. mannii
10’. Anthers <1 mm long; petals ≤ 2.5 mm long (up to 3 mm in female flowers); fruit ± rounded at apex, sparsely to densely velutinous. Lower Guinea and Congolia, extending to the areas of the Flora of Tropical East Africa and Flora Zambesiaca .......................................................................................... 10. T. lucens
11. Midrib of leaflets plane or prominent above ............................................................................................ 12
11’. Midrib of leaflets impressed above .......................................................................................................... 13
12. Corolla yellow; inflorescence glabrous to sparsely (sub)appressed-puberulous; pedicel glabrous, rarely with a few dispersed hairs; leaflets usually minutely pustulate above. Nigeria to Congo (Kinshasa).... 15. T. patens
12’. Corolla dark red to purple; inflorescence and pedicel (sub)appressed-puberulous; leaflets ± smooth above. Nigeria, Cameroun ................................................................................................................ 2. T. arborea
13. Inflorescence densely bracteate, at least until anthesis, the bracts boat-shaped, longer than the flower clusters that they subtend, densely appressed-pubescent outside, less densely so inside (Fig. 4). Gabon .................... ............................................................................................................................................ 4. T. bracteata
13’. Inflorescence not densely bracteate, at least not until anthesis; bracts shorter than the flower clusters that are subtended .............................................................................................................................................. 14
14. Petals with papillate margins, valvate in bud .......................................................................................... 15
14’. Petals imbricate in bud, at least narrowly so, margin thin, not papillate .................................................. 16
15. Shrubs up to 2 m tall; leaves (1-)3-5(-13)-foliolate; pedicel thin, ± thread-like, (2-)3-5(-7) mm long; petals distinctly and usually prominently veined outside; fruits glabrous. From SE Nigeria to Congo (Kinshasa) .. .............................................................................................................................................. 9. T. laxiflora
15’. Shrubs to treelets to 6 m tall; leaves 15-17-foliolate; pedicel ± stout, ≤ 1 mm long; petals not distinctly veined, appressed-pubescent outside; fruits velvety. Cameroun, Gabon .................................... 7. T. hallei
16. Inflorescences ± narrow, with ± fastigiate branches ≤ 7 cm, the flowers borne in spike-like units; ovary and fruit glabrous. Nigeria to Congo (Kinshasa) ............................................................................ 3. T. bijuga
16’. Inflorescences widely branched, branches up to 30 cm long, the flowers usually distinctly pedicelled, ± arranged in separate fascicles; ovary and fruit glabrous or hairy ............................................................ 17
17. Flowers white to yellow; ovary glabrous, rarely with a few hairs; fruit glabrous; upper surface of leaflets usually minutely pustulate to grumose. Cameroun to Congo (Kinshasa) ................................ 17. T. reygaertii
17’. Flowers pink to red; ovary velutinous; fruit subappressed-short-hairy; upper surface of leaflets smooth. Cameroun to Congo (Brazzaville) .................................................................................... 18. T. rubicunda
description: Published as part of Breteler, F. J., 2004, The genus Trichoscypha (Anacardiaceae) in Lower Guinea and Congolia: A synoptic revision, pp. 97-127 in Adansonia (3) (3) 26 (1) on pages 98-100, DOI: 10.5281/zenodo.4605259