Palynotaxonomy of Centauropsis (Compositae, Vernonieae) an endemic genus from Madagascar

Figures & data

Table I. Centauropsis dimensions (μm) pollen grains in equatorial and polar view using light microscopy.

Specimen	Equatorial axis (EV)			Polar axis (EV)			P/E	Form	Equatorial axis (PV)			Size
	CI – (x ± Sx) CI+	s	V%	CI – (x ± Sx) CI+	s	V%	x		CI – (x ± Sx) CI +	s	V%	CI
ant08	53.7 (54.5 ± 0.4) 55.3	1.9	3.6	49.0 (50.1 ± 0.6) 51.3	2.8	5.7	0.9	OS	54.3 (55.1 ± 0.4) 55.8	1.8	3.2	L
ant92	51.6 (52.3 ± 0.3) 53.0	1.7	3.3	46.6 (47.4 ± 0.4) 48.2	1.8	3.9	0.9	OS	52.5 (53.3 ± 0.4) 54.2	2.0	3.8	M* – L
cus34	44.2 (45.1 ± 0.5) 46.1	2.4	5.2	40.1 (40.8 ± 0.3) 41.1	1.6	4.0	0.9	OS	41.7 (42.5 ± 0.3) 43.2	1.7	4.0	M
cus60	43.0 (44.0 ± 0.5) 45.0	0.5	5.6	41.0 (42.0 ± 0.5) 42.9	2.4	5.7	1.0	OS	42.5 (43.5 ± 0.5) 44.5	2.5	5.7	M
cus63	42.0 (42.8 ± 0.4) 43.5	1.9	4.4	39.1 (39.7 ± 0.3) 40.4	1.6	4.0	0.9	OS	41.7 (42.5 ± 0.3) 43.2	1.7	4.0	M
dec86	45.6 (46.7 ± 0.5) 47.8	2.6	5.6	41.3 (42.3 ± 0.5) 43.2	2.4	5.6	0.9	OS	44.4 (45.2 ± 0.4) 46.0	1.9	4.3	M
dec87	48.2 (49.0 ± 0.4) 48.2	1.9	3.9	41.9 (42.9 ± 0.5) 43.9	2.5	5.8	0.9	OS	46.4 (47.3 ± 0.4) 48.1	2.1	4.5	M
fru36	49.8 (50.9 ± 0.6) 52.1	2.9	5.6	45.3 (46.0 ± 0.3) 46.7	1.6	3.5	0.9	OS	49.0 (50.5 ± 0.7) 52.0	3.6	7.2	M–L
fru54	46.9 (47.6 ± 0.4) 48.4	1.9	3.9	42.3 (43.0 ± 0.3) 43.6	1.6	3.6	0.9	OS	45.4 (46.3 ± 0.4) 47.3	2.2	4.9	M
per62	46.8 (47.3 ± 0.3) 47.8	1.3	2.7	41.1 (41.8 ± 0.3) 42.4	1.6	3.8	0.9	OS	45.1 (45.8 ± 0.4) 46.6	1.8	4.0	M
rha07	55.4 (56.5 ± 0.5) 57.6	2.6	4.7	52.5 (53.3 ± 0.4) 54.1	1.9	3.5	0.9	OS	55.5 (56.5 ± 0.5) 57.6	2.5	4.4	L
rha10	58.6 (59.7 ± 0.6) 60.9	2.8	4.7	55.0 (56.0 ± 0.5) 56.9	2.3	4.1	0.9	OS	58.0 (58.9 ± 0.4) 59.9	2.2	3.8	L
rha11	58.4 (59.2 ± 0.4) 60.1	2.1	3.5	54.5 (55.2 ± 0.3) 55.8	1.6	3.0	0.9	OS	57.6 (58.6 ± 0.5) 59.7	2.5	4.3	L

Note. Specimens were identified by the abbreviation of the epithet and the last two numbers of the herbarium voucher (see Specimen analysed). Equatorial view (EV), polar view (PV), confidence interval (CI) at 95% of probability of the lowest sample values (CI−) and highest sample values (CI+), arithmetic mean (x), average standard deviation (Sx), sample standard deviation (s), coefficient of variability (V%), oblate spheroidal (OS), large (L), medium (M).

Table II. Dimensions (μm) pollen grains aperture, spine, reticulum and exine layers in equatorial view using light microscopy.

Specimen	Colporus	Endoaperture	Spine	Exine
	L –W	W (W/L) L		S (S/N) N –E
ant08	33.8–8.4	10.3 (1.5) 6.7	3.5	5.9 (2.1) 2.8–8.7
ant92	32.1–9.7	12.5 (1.5) 8.6	3.5	5.3 (2.0) 2.6–7.9
cus34	26.9–5.3	10.9 (2.6) 4.3	3.5	4.3 (2.1) 2.0–6.3
cus60	31.1–6.4	11.1 (1.3) 8.8	2.5	3.6 (1.7) 2.1–5.7
cus63	24.9–4.0	10.0 (3.3) 3.1	4.2	4.3 (2.2) 2.0–6.3
dec86	28.6–5.6	10.7 (3.8) 2.9	5.0	4.3 (1.7) 2.5–6.8
dec87	30.2–7.1	14.8 (2.7) 5.5	5.0	4.3 (1.9) 2.3–6.6
fru36	33.6–8.4	12.7 (1.7) 7.7	4.1	4.4 (2.2) 2.0–6.4
fru54	29.9–6.3	10.3 (2.0) 5.1	4.3	4.5 (2.2) 2.0–6.5
per62	28.4–5.8	8.3 (1.7) 5.1	3.2	4.8 (2.6) 1.8–6.6
rha 07	36.4–9.7	14.1 (1.5) 9.8	5.0	4.7 (1.4) 3.2–8.0
rha 10	40.4–9.7	16.2 (1.6) 10.6	6.5	4.9 (1.5) 3.3–8.1
rha 11	42.0–9.5	13.0 (1.6) 8.2	4.8	4.0 (1.4) 2.7–6.7

Note. Specimens were identified by the abbreviation of the epithet and the last two numbers of the herbarium voucher (see Specimen analysed). Length (L), width (W), width/length (W/L), muri (M), lumen (Lum), sexine (S), sexine/nexine (S/N), nexine (N), exine (E).

Figure 1. Light microscopy of Centauropsis Bojer ex DC. pollen grains. A‒C. Centauropsis antanossi (Scott Elliot) Humbert. A. Detail of the colporus, endoaperture and surface, equatorial view. B. Apertures 3-colporate, long and acute apices and apocolpium surface. C. Optical section, equatorial view. D‒F. Centauropsis cuspidata Humbert. D. Detail of the colporus, endoaperture and surface, equatorial view. E. Apertures 3-colporate, long and acute apices and apocolpium surface. F. Optical section, equatorial view. G‒H. Centauropsis decaryi Humbert. G. Detail of the colporus, endoaperture and surface, equatorial view. H. Apertures 3-colporate, long and acute apices and apocolpium surface. I. Optical section, equatorial view. J‒L. Centauropsis fruticosa Bojer ex DC. J. Detail of the colporus, endoaperture and surface, equatorial view. K. Apertures 3-colporate, long and acute apices and apocolpium surface. L. Optical section, equatorial view. Scale bars – 10 μm (A‒C, G‒L), 8 μm (D‒F).

Figure 2. Scanning electron microscopy of Centauropsis Bojer ex DC. pollen grains. A‒C. Centauropsis antanossi (Scott Elliot) Humbert. A. General view of the mesocolpium, equatorial view. B. Detail of apertural membrane of the colporus, margo, and mesocolpium. C. Fractured pollen grain, structure of exine layers. D‒F. Centauropsis cuspidata Humbert. D. General view of the apertural area and mesocolpium, equatorial view. E. Detail of apocolpium, polar view. F. Detail of the spines and lophae on mesocolpium, equatorial view. G–I. Centauropsis decaryi Humbert. G. General view of the mesocolpium, equatorial view. H. General view of the apocolpium, polar view. I. Fractured pollen grain, structure of exine layers. J‒L. Centauropsis fruticosa Bojer ex DC. J. General view of the apertural area and mesocolpium, equatorial view. K. Detail of apocolpium, polar view L. Detail of apertural membrane of the colporus, margo, and mesocolpium. Scale bars – 10 μm (A, D, G, H, J), 1 μm (B, C, E, F, I, K, L).

Figure 3. Light microscopy of Centauropsis Bojer ex DC. pollen grains. A‒C. Centauropsis fruticosa var. baronii Humbert. A. Detail of the colporus, endoaperture and surface, equatorial view. B. Apertures 3-colporate, long and acute apices and apocolpium surface. C. Optical section, equatorial view. D‒F. Centauropsis perrieri Humbert. D. Detail of the colporus, endoaperture and surface, equatorial view. E. Apertures 3-colporate, long and acute apices and apocolpium surface. F. Optical section, equatorial view. G‒I. Centauropsis rhaponticoides Drake. G. Detail of the colporus, endoaperture and surface, equatorial view. H. Apertures 3-colporate, long and acute apices and apocolpium surface. I. Optical section, equatorial view. Scale bars – 10 μm (A‒C), 8 μm (D‒I).

Figure 4. Scanning electron microscopy of Centauropsis Bojer ex DC. pollen grains. A‒C. Centauropsis fruticosa var. baronii Humbert. A. General view of the apertural area, mesocolpium, and apocolpium, inclined equatorial view. B. Detail of the spines, lophae and microspines on mesocolpium, equatorial view. C. Fractured pollen grain, structure of exine layers. D‒F. Centauropsis perrieri Humbert. D. General view of the apertural area, mesocolpium, equatorial view. E. Detail of the apocolpium, polar view. F. Detail of apertural membrane of the colporus, margo, and mesocolpium. G‒I. Centauropsis rhaponticoides Drake. G. General view of the apertural area, mesocolpium, equatorial view. H. Detail of the apocolpium, polar view. I. Detail of the spines on mesocolpium, equatorial view. J, K. Fractured pollen grain, structure of exine layers of Centauropsis fruticosa var. baronii Humbert. L. Fractured pollen grain, structure of spine of Centauropsis perrieri Humbert. Scale bars ‒ 10 μm (A, D, G), 1 μm (B, C, E, F, H‒L).

Table III. Morphology and ultrasculpture of Centauropsis pollen grains using light and scanning electron microscopy.

Specie	Size	Form	Colporus	Endoaperture class, terminals	Spine base, apices	Lophae
Centauropsis antanossi	L – M*	Oblate spheroidal	Medium, pointed	Lalongate, rounded	Non- constricted, acute	Nanoreticulate
Centauropsis cuspidata	M	Oblate spheroidal to prolate spheroidal	Medium, pointed	Very lalongate or lalongate* rounded	Constricted, acute	Nanoreticulate
Centauropsis decaryi	M	Oblate	Long, rounded	Very lalongate, pointed	Non- constricted, acute	Nanoreticulate
Centauropsis fruticosa	M–L	Oblate spheroidal	Long, rounded	Very lalongate, rounded	Non- constricted, acute	Nanoreticulate
Centauropsis fruticosa var. baronii	M	Oblate spheroidal	Long, rounded	Very lalongate, pointed	Non- constricted, acute	Nanoreticulate-microechinate
Centauropsis perrieri	M	Oblate spheroidal	Medium, rounded	Vary lalongate, rounded	Non- constricted, acute	Nanoreticulate
Centauropsis rhaponticoides	L	Oblate spheroidal	Long, rounded	Lalongate to very lalongate, rounded	Non- constricted, obtuse	Nanoreticulate

Notes: Large (L), medium M).

Figure 5. Principal component analysis biplot of the pollen grain metric variables and classes/indices of Centauropsis specimens.

Table IV. Pearson and Kendall coefficients of pollen grain metric variables and classes/indices from the first two ordination axes of the principal component analysis (PCA) of Centoropsis species.

Principal components
Variables	Axis 1	Axis 2
EA	–1778	0.1366
PA	–0.1974	0.1288
PV	–0.1994	0.1266
CL	–0.2554	0.1070
CW	–0.4272	0.1156
EL	–0.6406	–0.2711
EW	–0.2153	0.3161
Se	–0.0547	0.0323
Ne	–0.1878	0.2537
Ex	–0.1191	0.1284
Ecl	0.3509	0.4973
Sp	0.0982	0.6491

EA, equatorial axis; PA, polar axis; PV, equatorial axis in polar view; CL, colpus length; CW, colpus width; EL, endoaperture length; EW, endoaperture width; Se, sexine thickness (S = infratectum + tectum); Ne, nexine thickness; Ex, exine thickness (Ex = N + S); Ecl, endoaperture class; Sp, spine length.

Figure 6. Dendrogram built from cluster analysis (Euclidean distance) for Centauropsis specimens, information remaining (%).