Wednesday, June 10, 2020

[Botany • 2020] Michaelmoelleria vietnamensis (Gesneriaceae) • A New Lithophilous Dwelling Genus and Species with Zigzag Corolla Tube from southern Vietnam

Michaelmoelleria vietnamensis  F. Wen, Z.B. Xin & T.V. Do

in Wen, Xin, Fu, Li, Su, et al., 2020. 
DOI:  10.3897/phytokeys.146.49731
Photos by Fang Wen

Michaelmoelleria, a new genus from southern Vietnam is described with a single species, M. vietnamensis. The new genus is morphologically most similar to Deinostigma and Tribounia but it differs from the latter two by having four fertile stamens. Nuclear ribosomal internal transcribed spacer (ITS) region and plastid trnL-F intron spacer (trnL-F) DNA sequence data from the new genus and eighty-seven species representing 42 genera within tribe Didymocarpeae are used to resolve its generic placement. The molecular evidence reveals that it is most closely related to Cathayanthe rather than Deinostigma and Tribounia. The chromosome number is counted as 2n = 36 that further clarified its distinction comparing to the related genera within tribe Didymocarpeae. A global conservation assessment is also performed and classifies Michaelmoelleria vietnamensis as Critically Endangered (CR).

Keywords: Cathayanthe, cliff-dwelling, Deinostigma, Didymocarpoideae, flora of Vietnam, IUCN, phylogeny, Tribounia

Figure 1. Photos of the new genus, Michaelmoelleria, the population in natural habitat.Michaelmoelleria vietnamensis F.Wen, Z.B.Xin & T.V.Do
A habitat along the La stream B habit C plants in flower D frontal view of flower in natural habitat E lateral view of flower in natural habitat.
Photos by Fang Wen, arranged by Wen-Hua Xu.

Figure 4. Photos of new genus, Michaelmoelleria F. Wen, Y.G. Wei & T.V. Do.
Michaelmoelleria vietnamensis F. Wen, Z.B. Xin & T.V. Do
A flowering potted plant in GCCC’s greenhouse B frontal view of the corolla and the corolla tube C different angles of a lateral view of corolla and corolla tube (I) D different angles of lateral view of the corolla and the corolla tube (II) E cyme F bracts (above: adaxial surface; below: abaxial surface) G calyx lobes H lateral view of flower and bud I calyx lobes (the left three: adaxial calyx lobes surfaces; the right two: abaxial calyx lobes surfaces) J opened corolla showing stamens and staminode K our fertile anthers L pistil and calyx M stigma.
Photos by Fang Wen, arranged by Wen-Hua Xu.

Michaelmoelleria F. Wen, Y.G. Wei & T.V. Do, gen. nov.

 Diagnosis: Michaelmoelleria resembles monotype genus Cathayanthe, but differs from the latter by leaf blade glabrous (vs. sericeous to pubescent in Cathayanthe, same as order followings); calyx actinomorphic (vs. zygomorphic); fertile stamens 4 (vs. 2), stigma 2, both developed ligulate (vs. 1, subcapitate, divided on 1 side); capsule long linear (vs. fleshly, narrowly ellipsoid). The new genus is also morphologically similar to Deinostigma and Tribounia, but is easily distinguished from both by having corolla tube narrowly curving to zigzag infundibuliform-tubular, and bent at about 90° angle in the middle of corolla tube (vs. infundibuliform in Deinostigma; of a narrow lower tube which widens into an infundibuliform & upper tube which has a prominent boss on the dorsal surface in Tribounia, same as order followings), fertile stamens number 4 (vs. 2; 2) and stigma 2-lobed, lobes often gathering together (vs. upper lip usually vestigial and only lower lip developing, broad, flat and weakly 2-lobed; capitate).

Type and only known species: Michaelmoelleria vietnamensis F. Wen, Z.B. Xin & T.V. Do, sp. nov.

Etymology: Michaelmoelleria was named in honor of Prof./Dr. Michael Möller from the Royal Botanic Garden Edinburgh. He is a well-known botanist studying Old World Gesneriaceae, especially in Africa (Madagascar) and Asia (China), and mentor of the senior author from the 1990s to the present. “Michaelmoeller-” (means “Michael Möller”) stands for his full name. “moeller” is the English modification of the German family name, “Möller”. Initially, we planned to use “Moelleria” as the genus name. However, this name was used in different places three times. They are Moelleria Cleve (Bacillariophyta, incertae sedis) [non Moelleria Scop. (Spermatophyta, Flacourtiaceae) (≡ Iroucana Aubl.)]; [nec Moelleria Bres. (Fungi, Clavicipitaceae) (≡ Moelleriella Bres.)] [nec Moelleria (Freng.) Freng. (Bacillariophyta, Naviculaceae)] (Blanco and Wetzel 2016). Thus, to prevent confusion with those mentioned above, three existing and existed “Moelleria”, we consider that using the variant of Dr. Michael Möller’s full name, “Michaelmoeller”, to name this new genus to be most appropriate.

Distribution and habitat: Endemic to southern Vietnam, under broadleaved forests in a montane granite area at 140–200 m altitude.

Michaelmoelleria vietnamensis F. Wen, Z.B. Xin & T.V. Do, sp. nov.

Etymology: The genus is named for the famous botanist, Dr. / Prof. Michael Möller, from the Royal Botanic Garden Edinburgh, and the species is named for Vietnam, which holds the first discovered and only known location for the species.

Figure 6. Photos of Deinostigma W.T.Wang & Z.Y.Li (A–E) and Tribounia D.J.Middleton (F–I),
the morphologically similar genera and species of Michaelmoelleria F.Wen, Y.G.Wei & T.V.Do (M. vietnamensis F.Wen, Z.B.Xin & T.V.Do)

A Deinostigma eberhardtii (Pellegr.) D.J.Middleton & H.J.Atkins B D. tamiana (B.L.Burtt) D.J.Middleton & H.J.Atkins C D. cycnostyla (B.L.Burtt) D.J.Middleton & H.J.Atkins D D. cicatricosa (W.T.Wang) D.J.Middleton & Mich.Möller E D. cyrtocarpa (D.Fang & L.Zeng) Mich.Möller & H.J.Atkins
F–G Tribounia venosa (Barnett) D.J.Middleton H–I T. grandiflora D.J.Middleton.
A–E photos by Fang Wen F–I photos by David Middleton, arranged by Wen-Hua Xu.


 Fang Wen, Zi-Bing Xin, Long-Fei Fu, Shu Li, Lan-Ying Su, Stephen Maciejewski, Zhang-Jie Huang, Truong Van Do and Yi-Gang Wei. 2020. Michaelmoelleria (Gesneriaceae), A New Lithophilous Dwelling Genus and Species with Zigzag Corolla Tube from southern Vietnam. PhytoKeys. 146: 89-107. DOI:  10.3897/phytokeys.146.49731