Cordylogyne argillicola Dinter, Repert., 2017

Bester, Stoffel P., Nicholas, Ashley & Ramdhani, Syd, 2017, An amplified description for the elusive Cordylogyne argillicola (Apocynaceae- Asclepiadoideae) from Namibia, Phytotaxa 321 (1), pp. 114-124 : 115-120

Cordylogyne argillicola Dinter, Repert. Spec. Nov. Regni Veg. 16: 242 (1919). ( Figs. 2 , 3 , 5 ).

Cordylogyne argillicola is morphologically closest to Cordylogyne globosa , Periglossum mackenii and P. kassnerianum Schlechter (1895: 40) from which it differs in the presence of folded flaps of tissue at the base of the restricted basal stalk of the corona-lobes. Further it does not have a “T”-shaped slit on the ventral surface of the corona-lobe, which is solid and smooth.

Type:— Namibia, (2217CC), Ombavumbu, Aris, 1791 m [22°45’0.88”S 17°08’0.19”E], 14 April 1911, M.K. Dinter 2254 (lectotype, SAM! [ SAM 0191348-0], designated here). Hoffnung ± 12 km ENE of Windhoek [2217CA: 22°32’23.91”S 17°11’47.38”E], 1937 m, December 1912, M.K. Dinter 2682 (syntype SAM! [ SAM 0071002-0]).

Perennial geophytic herb (to be confirmed, presumed due to generic affiliation), all parts with milky latex. Underground organ not seen. Stem 80–280 mm tall; 1–6 stems, well-branched from the base [Dinter 2254 & 2682] or solitary and flexuose (somewhat zigzagged) especially in the upper portion [Schoenfelder 239], sulcate to angular, sparingly puberulous to tomentose, on young growth only on one side; internodes 6–22 mm long. Leaves erect or ascending, petiole 0.8–4.2 mm long; blade linear to narrowly lanceolate, 5.7–65.0 × 0.7–4.9 mm [much shorter and narrower at the plant base], apex acute to acuminate, base attenuate and tapering, margins revolute to entire, pale below, midvein very prominent below, puberulous to tomentose on both sides, longer than internodes [Schoenfelder 239]; Inflorescences umbellate, solitary, extra-axillary, lateral at the upper nodes or terminal, 13–14 mm in diam., 1–4 per stem, subglobose, 3–10-flowered; peduncle 10.9–23.9 mm long, erect, sulcate, pilose to puberulous; pedicels 3.8–7.2 mm long, tomentose; bracts filiform to narrowly lanceolate, 1.20–2.35 × 0.014 –0.045 mm, dorsally pilose. Flower pentamerous, corolla cupulate and spreading-erect, 3.1–5.0 × 3.1–4.6 mm; calyx suberect, narrowly triangular to lanceolate to ovate, 1.5–2.4 × 0.6–1.7 mm, apex acute, dorsally puberulous to pilose, ventrally glabrous; colleters lanceolate with obtuse apices, 0.4–0.5 × ± 0.1 mm. Corolla ovate to oblong, obtuse and notched at tip, suberect to spreading, 2.7–3.8 × 1.0– 1.6 mm, glabrous on both sides, with narrow hyaline margin 0.17–0.21 mm broad (more pronounced on left-side of lobe as viewed ventrally); beige to off-white (sensu Dinter). Staminal corona -lobes erect, 1.3–2.5 × 0.7–1.8 mm, dorsoventrally flattened, ± level with the style-apex; blade ovate, 1.2–1.4 × 0.9–1.2 mm, apex obtuse and sometimes dilating suddenly, rounded to subacute, ventrally with two basal horn-shaped flaps 0.25–0.45 × 0.13–0.22 mm with their apices incurved towards each other; basal stalk 0.13–0.50 × 0.2–0.6 mm; interstaminal corona -lobes minute, ±90 × 90–107 μm, shallowly bilobed, at base of furrow below anther-wings. Gynostegium 1.7–1.9 × 2.1–2.4 mm. Androecium: staminal column 1.4–1.7 × 1.3–1.6 mm; anther trapeziform, 0.4–0.8 × 0.2–0.3 mm; anther-wings only on upper half of filament, triangular with obtuse base, 0.34–0.45 × 0.19–0.29 mm; with deep furrow below anther-wings 0.25–0.33 × 0.11–0.16 mm; anther-appendages broadly ovate, apex obtuse, 0.4–0.6 × 0.3–0.7 mm, appressed against and covering the base of the style-apex. Pollinarium: corpuscle ovoid, 100–150 × 34–50 μm; caudicle flat, twisted, winged apically, 110–287 × 44–71 μm, broader at base narrowing to point of attachment to corpuscle; pollinia wedge-shaped, 0.5–0.6 × 0.17–0.23 mm and 0.12–0.13 mm thick, with flat translucent apical germination zone. Gynoecium: style-apex conical, 0.4–0.6 × 0.4–1.0 mm, which is produced 0.6–0.7 mm beyond the anther-appendages, with two apical humps at the top; gynostegial fissure 0.3–0.6 mm long. Fruit and seed not seen.

Etymology:—The generic name is derived from a combination of the Greek words kordyle (meaning “a club”) and gyne (meaning “female”). This is in reference to the club-like style-apex which terminates the gynoecium or female whorl. The specific epithet is derived from the combination of agrilla (clay) and -cola (-dweller), most possibly in reference to the clay soils in which the plants were originally found.

Habitat and distribution:—Namibian endemic. Komas region near Windhoek and Omaruru. Known from only three locations: two approximately 25–30 km E and SW from Windhoek, and the third about ± 173 km NNW of Windhoek ( Fig. 1 ). Plants occur at a medium to high elevation of ± 1232–1931 m on the Windhoek plateau. This area is savanna underlain by vertic clay soils.

Phenology:—Plants seem to flower in mid- to late-summer, from December (Dinter 2682, in full anthesis) to April (Dinter2254, in bud only).

Conservation status:—This species has only been re-collected once since the two collections of Dinter more than a century ago. It is known from only three locations: two that are ± 24 km apart (one at the farm Hoffnung ± 12 km ENE of Windhoek (Dinter 2682) and the other from Aris ± 21 km SSE from Windhoek (Dinter 2254), and the third from Omaruru, ± 173 km NW of Windhoek (Schoenfelder 239). This last specimen unfortunately had no details captured on the sheet other than the number. Schoenfelder’s collection book was, however, traced at the Mary Gunn library at PRE where the place name “Ombaruru” was cited for this specimen. No date or habitat information was recorded in his collectors list. One of the locations might be under pressure of residential development due to an expanding Windhoek. As the species has not been collected in the past 100 years it can only be classified as Data Deficient according to the IUCN (2001) criteria. Based on the current knowledge and using the conservation assessment tool ( Bachman et al. 2011) a preliminary assessment of Endangered is proposed as the species is only known from three locations with an Extent of Occurrence (EOO) estimated at 3239.209 km 2 and Area of Occupancy of 12 km 2.

Discussion:—On the SAM sheet there are three specimens belonging to two collections ( Fig. 2 ). We regard the top label to belong to the top specimen and barcode (indicated with the red arrows), this being Dinter 2682 [SAM0071002- 0], a specimen in full anthesis. The middle label with lower barcode belong to the two specimens mounted at the bottom of the sheet, one fragment sterile the other only containing flower buds, this is Dinter 2254 [SAM0191348-0]). It is clear that these specimens were not originally one collection as it seems that at the time that they were brought together the middle label and both determinative slips of Greenway were cut out and added to the sheet. In the original publication of the name, Cordylogyne argillicola, Dinter (1919) cited two specimens collected from different localities in Namibia and they are syntypes (McNeil et al. 2012, Art 9.5) as both are cited in the protologue. The first syntype listed is clearly indicated as Dinter 2254, collected near Aris and corresponds to the lower collection on the sheet. The second syntype mentioned by Dinter was only designated with locality information and the collector’s number was not as concretely referenced as the first syntype in which the collector’s name and number were clearly cited with locality information. This places preference for selection as lectotype on the Dinter 2254 specimen, rather than Dinter 2682, since the former is unmistakably linked to the original description. It is highly possible that the second cited specimen could be Dinter 2682 as no other material of Dinter representing C. argillicola could be traced. We have thus selected Dinter 2254 as lectotype and listed the remaining specimen (Dinter 2682) as a syntype in our synopsis in accordance with the rules and recommendations of the Melbourne Code (McNeil et al. 2012, Art. 40, Note 2).

Plants of C. globosa are usually associated with moist or seasonally moist situations in grasslands in arid areas. Specimens are exclusively collected from wetlands, marshy areas and floodplains and are, therefore, not usually subjected to annual grassland fires. In the Free State and Mpumalanga Provinces they are quite commonly found where water accumulates in road verges (Nicholas & Bester, personal observations). Like most species within the Schizoglossum complex, Cordylogyne is also very sparsely distributed and on many labels of specimens it is noted that the plants are rare. In comparison C. argillicola is located in savanna habitats and unfortunately the specimens do not make any reference to how wet (or not) the habitat is.

With the rediscovery of the two specimens of Dinter and the one of Schoenfelder, the genus now undeniably consists of two species. The most distinguishing feature of C. globosa is the club-shaped style-apex that projects well above the anthers in most specimens ( Fig. 4 ). In comparison C. argillicola has a shorter gynostegial head that may be bifid or conical and not globose like as in C. globosa . In the flowers examined of the former the head does not elongate, but in specimens of the latter it may either be elongate or not, but always with a pronounced globose head that is much broader than the stalk itself. Like Periglossum , C. globosa is also unique in having a sedge-like stem and fairly simple corona-lobes, but in contrast C. argillicola has a spreading habit with the peduncles of the inflorescences much shorter than in C. globosa .

The genera Cordylogyne (two species) and Periglossum (four species) are small, but well-defined morphologically and molecularly (Bester et al., unpublished). Dinter only gave a brief and depauperate description for C. argillicola . Besides differing from C. globosa in flower colour (the type of C. globosa of Mrs. Barber’s collection ( Dinter 1919)), C. argillicola also differs markedly from C. globosa in habit, where one or more stems of the latter are long and erect compared to the much more scrambling stems of the former. C. argillicola indeed resembles C. globosa , but differs further in the diminutive stature of the plants, the much more ovate anther-appendages and the style-head that is short and conical (not globose as in C. globosa ). More fieldwork needs to be done to re-collect material of this taxon in order to establish its habitat requirements, full extent of occurrence and an updated conservation assessment.

Figures

FIGURE 1.—Known distribution of the genus Cordylogyne: C. globosa (●) endemic to the eastern regions of South Africa and C. argillicola (▲) endemic to Namibia. Map created in ArcGIS10.1.

FIGURE 2.—Cordylogyne argillicola. Scan of the sheet containing the syntype, Dinter 2682 (SAM!) [the specimen at the top, left of the sheet indicated in red arrows] and lectotype, Dinter 2254 (SAM!) [two fragments at bottom].

FIGURE 3.—Cordylogyne agrillicola. A. Habit. B. Flowers, vertical view from outside. C. Staminal corona-lobes in ventral view. D. Staminal corona-lobes in dorsal view. E. Gynostegium (calyx and corolla removed). F. Pollinarium. Voucher: Dinter 2682 (SAM!). Scale bars:A, 10 mm; B–E, 0.5 mm; F, 0.2 mm. Artist: G.S. Condy.

FIGURE 4.—Cordylogyne globosa. A. Flower in angled side view. B. Flower, side view, staminal corona-lobe removed to expose gynostegial column. C. Staminal corona-lobes in ventral view. D. Close-up of gynostegial column showing anthers, anther-wings and anther-appendages. E. Close-up of gynostegial column showing anthers, anther-wings and anther-appendages. F. Pollinaria. Vouchers: A, B, D, Germishuizen 1048 (PRE!); C, Moss 15909 (BM!); E, F, Bester 8191 (PRE!). Scale bars: A–C, 0.5 mm; D–F, 0.2 mm. Photos: S.P. Bester.

FIGURE 5.—Cordylogyne argillicola. A. Bud in side-view. B. Corolla lobe (left) and two calyx lobes (right), both in ventral view. C. Colleter (shown with arrow) between calyx lobes in ventral view. D. Interstaminal corona-lobes with two flaps of tissue on ventral side of blade. Voucher: Dinter 2682 (SAM!). Scale bars: A, B, D, E, 0.5 mm; C, F, 0.2 mm. Photos: S.P. Bester.