Afrothismia kupensis Cheek & S.A. Williams, 2019
publication ID |
https://doi.org/10.3767/blumea.2019.64.02.06 |
persistent identifier |
https://treatment.plazi.org/id/03C787C7-CD58-157C-FFE2-1508FD13FC02 |
treatment provided by |
Felipe |
scientific name |
Afrothismia kupensis Cheek & S.A. Williams |
status |
sp. nov. |
Afrothismia kupensis Cheek & S.A. Williams View in CoL , sp. nov. — Fig. 1 View Fig
Differing from Afrothismia gesnerioides H.Maas in the monomorphic,patent or forward-directed tepals (not dimorphic, reflexed), the annulus strongly asymmetric, 3 mm long on the dorsal side but reducing to a flange projecting 0.5 mm on the ventral side (not with an even flange projecting 0.5 mm the entire circumference),inner surface of lower perianth tube sparsely hairy (not glabrous).Differing from Afrothismia pachyantha Schltr. in the tubular,slightly sigmoid perianth tube (not globose), the straight, flat tepals held away from the mouth of the perianth tube (not incurved,occluding the mouth of the tube), stigma entire (not 6-lobed), flange present just above the filament insertion (vs staminal flange absent), upper perianth tube well-developed above an annulus, as long as lower perianth tube (vs upper perianth tube extremely contracted and inconspicuous). — Type: Etuge 1831 (holo K, iso SCA, YA), Cameroon, South West Region, Kupe-Muanenguba, Tombel, Kupe village, 1200 m, fl. & fr., 28 Mar. 1996.
Afrothismia pachyantha sensu Cheek et al. (2004: 188 View in CoL , 429, f. 15B; Cheek & Onana 2011: 358), non Schltr. (1906).
Afrothismia gesnerioides sensu Merckx 2008: 123 View in CoL , 126, f. 8.1A, 137 f. 8.8; Onana 2013: 218 p.p.; Imhof et al. (2013); Sainge et al. (2017), non Maas-van de Kamer (2003).
Etymology. Named for both Mt Kupe and the people of Kupe village that hosted us during our several weeks of botanical surveys in their forest.
Achlorophyllous mycotrophic herb with only the flower or fruit emerging above the leaf-litter. Stem (rhizome), succulent, concealed in substrate, vertical, unbranched, c. 45 mm long, 2 mm diam, scale-leaves ovate-triangular, c. 0.3 by 0.15 mm, axillary buds globose, internodes (0.3–) 1.5 mm long. Bulbil cluster c. 15 by 17.5 mm, bulbils globose, each 1.5–2.5 mm diam, with an apical rootlet c. 2 mm long. Flowers developing in succession from the stems, 1-flower per stem open at a time, bract ovate, 7–8 by 3–4 mm, apex obtuse. Perianth tube directed horizontally, 16–17 mm long, 9 mm wide at midpoint, slightly S-shaped, constricted slightly between lower (proximal) and upper (distal) parts of the tube; outer surface white with 6 longitudinal purple lines on the lower tube, the upper tube purple in the proximal half, the distal half dull white, glabrous and lacking projections. Lower perianth tube horizontal or elevated <45° above the horizontal, 9–10 mm along main axis from top of ovary/base of perianth tube to annulus, widening from 6.5 mm diam at junction with ovary, to 8.5–9 mm wide, but constricted to 7.5 mm wide at staminal filament insertion whorl, 6.5 mm from the ovary, inner surface with an internal flange immediately above the insertion of the staminal filaments, flange continuous, shallowly lobed, lobes 6, alternating with stamens, 0.5–1 by 3 mm ( Fig. 1d View Fig ), inner surface below the staminal flange minutely and sparsely hairy. Annulus inserted c. 4 mm above the free staminal filament and flange insertion, strongly asymmetric: on the dorsal side projecting 3 mm from the upper perianth into the lower perianth tube, on the ventral side narrowing gradually and evenly to <0.5 mm wide. Upper perianth tube with axis at first ascending from that of the lower perianth tube, then curving to the horizontal at the mouth, c. 7.5 mm long from insertion of the annulus to insertion of the perianth lobes (dorsal surface) and 6 mm long (ventral surface), 7 mm wide above the annulus, narrowing to c. 6 mm wide at the mouth, the tube projecting beyond the insertion of the perianth lobes for c. 1 mm, inner surface glabrous. Tepals six, monomorphic (equal), patent or ± forward-directed, dull white, ovate-triangular, 3.5–4 by 2.5–3.5 mm, apex obtuseapiculate, glabrous. Stamens 6, staminal filaments joined to perianth tube for c. 6 mm, appearing as purple lines on exterior tube surface, distal part free, terete c. 1.5 mm long, arching inward to stigma, anthers 0.9–1 mm long, 0.5 mm wide, the 2 thecae c. 0.01–0.02 mm wide, separated by connective ( Fig. 1f View Fig ); distal connective appendage triangular, 0.6–0.75 by 0.3 mm, joined to stigmatic surface ( Fig. 1e View Fig ). Ovary turbinate, 4.5 mm long, 6–6.5 mm wide at junction with perianth; placenta- tion axile (placenta attached at base and apex), the ovules inserted on a recurved placental flange inserted in the centre of the ovary. Style cylindrical, 2 mm long, 1 mm diam, stigma obconical, c. 2.5 by 3.5 mm, lobes not detected, entire surface densely covered in 0.2 mm long patent hairs. Fruit turbinate, 8.5 mm long including lacerate perianth tube remains, 6.5 mm diam ( Fig. 1g –h View Fig ). Circumscissile dehiscence, the lid of fruit (perianth floor) detaching from the rest of the fruit, exposing the seed-covered placenta. Seeds numerous, narrowly obovoid, c. 1.5 by 0.5 mm, lacking appendages ( Fig. 1i View Fig ).
Distribution & Ecology — Lower submontane forest on SW and W slopes of Mt Kupe; 800–1200 m above sea-level. The following additional associated achlorophyllous species occurred intermingled with Afrothismia kupensis at the type locality near Kupe village site on the SW slopes of Mt Kupe: Sebaea oligantha Schinz ( Gentianaceae ), Burmannia hexaptera Schltr. , Burmannia congesta (C.H.Wright) Jonker (also known as Campylosiphon congestus (C.H. Wright) Maas ), Gymnosiphon longistylus (Benth.) Hutch. (all Burmanniaceae ) and Sciaphila ledermannii Engl. ( Triuridaceae ). These species occurred together in an area a little larger than 25 by 25 m. The leaf-litter covered surface slopes steeply with an inclination of about 40 degrees from the horizontal.
Mt Kupe (also known as Mount Kupe or Mont Koupé) is part of the Cameroon line of highlands and rises to 2 095 m above sea-level. Preliminary notes on the vegetation and species of the mountain can be found in Stoffelen et al. (1997) but a more comprehensive account is Cheek et al. (2004). 33 plant taxa were listed as being strictly endemic to the cloud forest of Mt Kupe ( Cheek et al. 2004: 39), among which were listed Afrothismia kupensis (erroneously as A. pachyantha ) and Kupea martinetugei Cheek & S.A.Williams ( Cheek et al. 2003) another achlorophyllous mycotroph, which was shown to be a new tribe, Kupeaeae, sister to the rest of the Triuridaceae ( Cheek 2004b) . However, at that time, 23 of the 33 strictly endemic taxa were still undescribed. Since that time a further ten new species have been described from those 23, leaving 13 still to be formally published. Most recently published are Microcos magnifica Cheek ( Cheek 2017) and Kupeantha kupensis Cheek & Sonké ( Cheek et al. 2018a).
Among the new species were two new genera to science: Kupeantha Cheek and Kupea Cheek & S.A.Williams ( Cheek et al. 2003, 2018a).
Some of the original 33 strictly endemic taxa have since been found also at other locations such as at Mt Etinde, 70–80 km to the SW along the Cameroon line, e.g., Dracaena kupensis Mwachala et al. ( Mwachala et al. 2007). Likewise it remains possible that some apparent site endemics at these other locations, such as Impatiens etindensis ( Cheek & Fischer 1999) at Mt Etinde, might yet be found at Mt Kupe. Clearance of forest upslope for subsistence agriculture from the many small villages which surround the Mt Kupe is a concern, and has reached up to 1 500 m altitude on the eastern flank of the mountain.
Additional material. CAMEROON, South West Region , Kupe-Muanenguba , Tombel , Kupe village, Williams s.n. (K, SCA, YA), 1200 m, fl. & fr., 28 Nov. 1995 .
Conservation — The conservation status of Afrothismia kupensis was assessed under the erroneously applied name of Afrothismia pachyantha (Cheek 2004c, Cheek et al. 2004: 188). This assessment was maintained, under the same misapplied name, in Onana & Cheek (2011: 358). In those assessments, Afrothismia pachyantha was regarded as extinct at the type location of Moliwe near Mt Cameroon and so the assessment was based solely on what were then thought to be the only surviving plants of the species at Mt Kupe, shown in this paper to be a separate species, A. kupensis . Afrothismia kupensis was known from one site near Kupe village, measuring less than 50 by 50 m ( Cheek et al. 2004). However, a second site at Mt Kupe was recently reported (as A. gesnerioides ) by Sainge et al. (2017), from near the village of Mbulle. However, both sites face the same threat: clearance of their habitat for small-holder farming.
The area of occupation is estimated as 8 km 2 using the IUCN preferred 4 km 2 cell size and extent of occurrence as <100 km 2. Therefore the two sites comprise a single threat-based location in the sense of IUCN (2012) and the assessment of Critically Endangered – CR B1+B2ab(iii); C2a(i); D1 is maintained here. However the assessment of A2c given in Onana & Cheek (2011) no longer applies since the Moliwe population is now known to be a separate species ( Afrothismia pachyantha now presumed extinct), so the decline in population of 80 % signified by A2c can no longer be evidenced for A. kupensis .
At the Kupe village site the authors of this paper had engaged with the local community to protect the forest in which A. kupensis is found through a rental and monitoring programme. However, the insecurity since 2016 due to the struggle for independence of the Anglophone sector of Cameroon (https:// www.today.ng/topic/ambazonia) means that such conservation activity is now difficult to continue.
Note — With the addition of Afrothismisa kupensis , the Cross-Sanaga interval (SE Nigeria and western Cameroon) now holds ten of the 16 described species of the genus, all but two of which are confined to it. The species in this area show the greatest range of morphological diversity in the genus. These factors suggest that the genus may have originated in the Cross-Sanaga area.
RESULTS AND DISCUSSION – FLORAL VISITATION STUDIES
The 23.5 hour floral visitor observation period was spread over seven days. Between 1.5 and 7 hrs each day were spent observing, between the hours of 8am and 5pm (see Table 2). Ten individual insects were observed to land on the flowers, all being judged by size, appearance and behaviour to be the same species, resembling a mosquito. Of these, seven entered the flower, each spending 3–9 seconds within the flower (median 5 seconds, average 6 seconds) before departing ( Table 2). Six of the 10 visitors arrived between 9.30 am and 10.30 am, while eight of the ten visitors arrived between 9.30 am and 11 am. On two of the seven days no visitors were recorded, while at the other extreme three visitors per day were observed on two other days. The median was one insect visitor per day ( Table 2). Two insects were retained for study.
From the insect body washings, Dr Hannah Banks of the Palynology Unit, Royal Botanic Gardens, Kew, reported that Thismiaceae type pollen predominated among the pollen grains captured. The results from the Natural History Museum Insect Identification Service were as follows: “Both samples are female scuttle Flies in the family Phoridae and are almost certainly the same species, possibly belonging to Megaselia which is the largest genus in the family, accounting for almost half the species in this large family. Over 200 genera and 2 500 species of Phoridae have been described and the actual total is likely to be significantly higher than this, with several species still undescribed. Their biology is highly variable, the larvae of many species being saprophagous but others are parasitic or fungivorous and others are associated with the nests of social insects such as bees, ants or termites. Adults of many species visit flowers and are likely to be significant pollinators of some species.”
It seems probable that the scuttle Flies ( Phoridae ) sampled do act as pollinators to Afrothismia kupensis since they were found to be carrying pollen of Thismiaceae following visitation to the flowers. That these scuttle Flies were the only floral visitors during the study period and that both of those preserved were almost certainly the same species suggests that this one species of insect might be the only pollinator of Afrothismia kupensis present at this site and at this time. However, this study of floral visitors was far from comprehensive, being carried out only during the day over one week. Nonetheless, this appears to be the first reported observation of pollination in the Thismiaceae . Pollination by Phoridae has been shown in other plant families, such as in Herrania Goudot ( Byttneriaceae ) by Young (1984) and in Aristolochia inflata Kunth ( Aristolochiaceae ) by Sakai (2002). In both cases female flies are thought to be attracted to the flowers by scent, effect pollination and to lay eggs inside the flower. In the last case, characterised as a mutualism, the eggs hatch and feed on the inner tissue of the fallen flower for seven days before pupating, adults emerging 15 days after the eggs are laid. However in another species of the same genus, 96 % of the flies attracted were males ( Hall & Brown 1993).
Further studies are recommended to discover if, as in Aristolochia inflata , the fallen flowers of Afrothismia kupensis provide the larval food for the Phorideae pollinator species, evidencing a mutualism. Surveying other species of Afrothismia in the field is suggested to determine if Phorideae are also pollinators or whether other groups of organisms effect pollination.
SCA |
Limbe Botanical and Zoological Gardens |
YA |
National Herbarium of Cameroon |
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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Genus |
Afrothismia kupensis Cheek & S.A. Williams
Cheek, M., Etuge, M. & Williams, S. A. 2019 |
Afrothismia pachyantha sensu
Onana JM & Cheek M. 2011: 358 |
Cheek M & Pollard BJ & Darbyshire I 2004: 188 |