Distant populations of a <i>Xanthosoma</i> (Araceae) species have different floral scents but the same cyclocephaline beetle pollinators

Gottsberger, Gerhard; Silberbauer-Gottsberger, Ilse; Dötterl, Stefan

doi:10.1590/0102-33062020abb0013

Gerhard Gottsberger ^** Corresponding author: gerhard.gottsberger@uni-ulm.de

Botanischer Garten/Herbarium, Universität Ulm, 89081, Ulm, Germany

https://orcid.org/0000-0003-3816-0520

Ilse Silberbauer-Gottsberger

Botanischer Garten/Herbarium, Universität Ulm, 89081, Ulm, Germany

https://orcid.org/0000-0002-0690-9966

Stefan Dötterl

Department of Biosciences, Paris-Lodron-University of Salzburg, 5020, Salzburg, Austria

https://orcid.org/0000-0001-5228-1332

* Corresponding author: gerhard.gottsberger@uni-ulm.de

Figures (5)
Tables (1)

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Figure 1
Location of the study sites of Xanthosoma striatipes in Brazil in the States São Paulo (Botucatu), Minas Gerais (Indianópolis) and Maranhão (Codó) used in the present study as well as in the Distrito Federal (Guará) and Tocantins (Arraias) used in the study by Milet-Pinheiro et al. (2017). The distance between the southernmost site, Botucatu, and the northernmost site, Codó, is approximately 2,050 km. The dotted lines on the map indicate major rivers.

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Figure 2
The large X. striatipes population in Codó, State of Maranhão, growing in a swamp.

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Figure 3
A. Warming of one inflorescence of X. striatipes in Botucatu, State of São Paulo, during the pistillate and the staminate stage in two subsequent days (November 18 and 19, 2007). B. Warming of four inflorescences of different individuals of X. striatipes, one in the staminate and the other three in the pistillate stage during one day (Indianópolis, State of Minas Gerais (December 12, 1986).

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Figure 4
Xanthosoma striatipes at Indianópolis, State of Minas Gerais. A. One individual of Cyclocephala ohausiana (left) and an individual of C. atricapilla (right) have approached a warm and smelling spadix in the pistillate stage. B. An opened inflorescence in the pistillate stage. Several individuals of C. ohausiana and probably also of C. atricapilla in the basal tube are contacting the receptive stigmas and gnawing on sterile staminate flowers. The length of the beetles is ca. 1.8 cm.

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Figure 5
An inflorescence in the second night in the staminate stage, with male flowers producing pollen grains in form of chains, which are eaten by beetles coming out of the tube and crawling upwards. A. Probably, a C. ohausiana beetle eating pollen. B. Several C. ohausiana individuals in search of remnants of pollen shortly before flying away. The length of the beetles is ca. 1.8 cm.

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Table 1
Relative amount of scent compounds (%) detected in the two scent samples of Xanthosoma striatipes analysed in the present study and in the two samples of this species analysed by Milet-Pinheiro et al. (2017). The samples of the present study were collected in Botucatu, São Paulo, those of Milet-Pinheiro et al. (2017) in Guará, Distrito Federal und Arraias, Tocantins. tr: < 0.05 %. Compounds are ordered according to chemical classes and within classes according to retention time. The identification of the compounds marked with an asterisk is based on synthetic reference compounds. Compounds printed in italics were only detected in the study of Milet-Pinheiro et al. (2017), and underlined compounds were found both in the present and the previous study.

	Sample 1	Sample 2	Data of *Milet-Pinheiro et al. 2017*
Aliphatics
Butan-2-yl acetate			4.1^c
Pent-1-en-3-yl acetate			0.1^c
Aromatics			tr^c
Methyl benzoate			tr^c
1,2-Dimethoxybenzene*	tr	tr	tr^c
1,4-Dimethoxybenzene*	tr	tr
Methyl salicylate*	32.7	23.8	4.9-6.5
Isobutyl benzoate	0.1	0.2
Methyl o-anisate*	19.0	16.3
1,2,4-Trimethoxybenzene*	0.1	0.1
1,3,5-Trimethoxybenzene*	17.2	17.7
a Tetramethoxybenzene	0.1	0.2
C5-branched chain compounds
Methyl 2-methylbutyrate*	tr	1.1
Miscellaneous cyclic compounds
Isojasmol ^a			21.6^c
Dehydrojasmone ^b			16.9^c
(E)-Jasmone			tr^c
(Z)-Jasmone			0.1-51.2
Dihydro- β -ionone			8.0^c
7,8-Dihydro- β -ionol			0.1^c
Methyl jasmonate*	17.2	18.1
S-containing compounds
4-Methyl-5-vinylthiazole*	1.7	2.2
4-Methyl-5-formylthiazole	tr	tr
Terpenoids
Sabinene*	tr	0.1
β-Myrcene*	tr	0.1	0.2^c
Limonene			tr^c
Eucalyptol*	0.1	0.8	tr^c
(Z)-β-Ocimene			tr^c
(E)-β-Ocimene*	0.1	0.4	0.2-0.9
γ-Terpinene*	tr	tr
(E)-Linalool oxide furanoid* + Terpinolene*	tr	0.1
(Z)-4,8-Dimethyl-1,3,7-nonatriene*	0.4	2.1
Linalool*	0.3	0.2
(E)-4,8-Dimethyl-1,3,7-nonatriene*	9.9	14.6	0.5-82.4
α-Terpineol*	0.3	1
(E)-4,8-Dimethylnona-1,3,7-trien-5-yl acetate*	tr	tr
Theaspirane isomer 1			0.1^c
Theaspirane isomer 2			tr^c
β-Caryophyllene*	0.1	0.2	tr^c
(E)-β-Farnesene*	tr	tr
(E)-8(9)-dehydro4(5)-dihydrotheaspirone	tr	tr
α-Caryophyllene*	tr	0.0
Unknowns
Sum unknowns^{11 pooled}	0.5	0.6
unknown mw 91, 119, 105, 40, 77			0.9^c
unknown mw 79, 69, 41, 81, 93			0.1^c
unknown mw 117, 91, 94, 95, 79			1.1^c

[TFN1] ^{aand b}
these compounds were listed by et al.) as unknown with retention indices 1301 and 1305, respectively. See text for more details about the identity of these compounds. tr = trace

[TFN2] ^c
compound occurred only in one of the two samples analysed by et al.).

Distant populations of a Xanthosoma (Araceae) species have different floral scents but the same cyclocephaline beetle pollinators

ABSTRACT