Rotheca microphylla (Blume) Callm. & Phillipson

Callmander, Martin W., Phillipson, Peter B., Wearn, James A. & de Kok, Rogier P. J., 2013, Adieu Adelosa Blume (Lamiaceae): Further observations on Rotheca Raf. for Madagascar, Candollea 68 (2), pp. 316-320 : 317-318

Rotheca microphylla (Blume) Callm. & Phillipson , comb. nova.

Ξ Adelosa microphylla Blume , Mus. Bot. 1: 176. 1850.

Typus: MADAGASCAR. Prov. Antsiranana: Ambongo , croît au bord de la mer, 14.II.1841, fl., Pervillé 626 (holo-: L [ L0062225 ]!; iso-: P [ P00091374 , P00091375 ]!, NY [ NY00103724 ] image seen).

= Clerodendrum incisum Klotzsch in Peters , Naturw. Reise Mossambique, Bot. 1: 257. 1861. Ξ Rotheca incisa (Klotzsch) Steane & Mabb. in Novon 8: 205. 1998.

Typus: MOZAMBIQUE: Rios de Sena, Querimba & Boror , Peters s.n. (holo-: B; iso-: K [ K000192940 ]!), syn. nov.

= Clerodendrum macrosiphon Hook f. in Curtis’s Bot. Mag.: tab. 6695. 1883. Ξ Clerodendrum incisum var. macrosiphon (Hook. f.) Baker in Fries, Fl. Scan. 5: 307. 1900.

Typus: TANZANIA. Zanzibar: Usaramo , Hort. Kew , 19.V.1882, Kirk s.n. (holo-: K [ K000607526 ]!), syn. nov.

= Clerodendrum lindemuthianum Vatke in Linnea 4: 348. 1896.

Typus: MADAGASCAR. Prov. Antsiranana: Vavatobé , II.1880, fl., Hildebrandt 3332 (holo-: B; iso-: BM [ BM000923603 ] image seen, K [ K000192958 ]!; P [ P00446638 , P00446639 ]!), syn. nov.

= Clerodendrum bernieri Briq. in Bull. Herb. Boissier 4: 348. 1896.

Typus: MADAGASCAR. Prov. Antsiranana: sur les rochers calcaire de Lingvatou , [12°26’S 49°30’E], 1835, fl., Bernier 169 (2 e envoi) (holo-: G [ G00366 312 ]!; iso-: P [ P00446637 , P02865951 , P02865955 ]!), syn. nov.

= Clerodendrum pusillum Gürke in Bot. Jahrb. Syst. 30: 390. 1901.

Typus: TANZANIA. MBEYA DISTR.: Unyika, Nsangamales , s.d., Goetze 1393 (holo-: B), syn. nov .

= Clerodendrum incisum var. vinosum Chiov., Fl. Somala 2: 364. 1932.

Typus: SOMALIA: Licchitore, 22.VII. 1929, fl., Senni 542 (holo-: FT [ FT002833 ] image seen), syn. nov.

= Clerodendrum incisum var. longepedunculatum B. Thomas in Bot. Jahrb. Syst. 68: 78. 1936. Typus: Kenya: coast opposite Lamu, s.d, Hildebrandt 1911 (holo-: B), syn. nov.

= Clerodendrum incisum var. parvifolium Moldenke in Phytologia 3: 407. 1951.

Typus: MADAGASCAR. Prov. Antsiranana: Vallée moyenne du Mandrare , prÈs d’Andadabolava, Mont Vohitrosy , 800-850 m, XII. 1933, fl., Humbert 12741 (holo-: P [ P00446640 ]!; iso-: NY [ NY001377354 ] image seen, P [ P00446641 ]!), syn. nov.

= Clerodendrum incisum var. afzelii Moldenke in Amer. J. Bot. 38: 325. 1951.

Typus: MADAGASCAR. Prov. Tulear: Manasoa Tanosy , 13.I.1913, fl., Afzelius s.n. (holo-: K [ K000607527 ]!; iso-: NY image seen), syn. nov.

= Clerodendrum dalei Moldenke in Phytologia 4: 287. 1953.

Typus: KENYA: near Marjoreni, S. Digo , IX. 1937, fl., Dale 3811 (holo-: BR [ BR0000008715517 ] image seen; iso-: EA [ EA000001136 , EA000001137 ] images seen, K [ K000192876 ]!, NY [ NY00137334 ] image seen), syn. nov.

Observations. – Rotheca microphylla is a highly variable species that occurs throughout much of western, southern and northern Madagascar ( Fig. 1 ), where it is largely confined to the Dry Bioclimatic Region ( CORNET,1974), and the western slopes of the central plateau. It is also native to eastern and southern parts of Africa in Angola, Kenya, Malawi, Mozambique, Somalia, Tanzania (including Zanzibar) and Zambia. It occurs in dry forest and woodland, mostly from sea level to about 800 m elevation, but occasionally higher, where it forms a lianescent shrub typically scrambling up to c. 3 m high or more in the under-storey and on the forest margins, but sometimes even higher. It also grows in open areas of degraded forest, bush and secondary anthropogenic grassland, where it tends to develop a low-growing spreading growth-form. It appears to be somewhat tolerant of grazing, trampling and burning and can become locally abundant in disturbed habitats with a somewhat weedy tendency. With its prolific flowers, distinctive erect crochet-like buds, and conspicuous long white corolla tube and spreading lobes (see Fig. 2 ), it is a decorative plant that has been introduced into cultivation as an ornamental in tropical and sub-tropical gardens in various parts of the world, sometimes marketed in North America as the “Musical-note Plant”.

In addition to its variable habit, the diversity in Rotheca microphylla is most marked with respect to leaf shape and size. In Madagascar leaves vary froml anceolate and no more than 25 × 8 mm and almost entire with at most a few shallow marginal teeth, to elliptic and as much as 100 × 50 with coarsely serrate margins. To some extent this variation is also correlated with habitat and locality, the small-leaved specimens occurring in exposed arid places such as Isalo National Park, and the large-leaved specimens from more humid forest locations such as Manongarivo Special Reserve, but floral characteristics appear to be quite constant. In Africa most collections have large leaves, and the marginal teeth tend to be fewer and more deeply incised, but again the floral morphology is not distinguishable from the Malagasy plants. It is tempting to separate the Malagasy and African plants as different species, but after careful examinations of specimen held at G, K, P and MO, we believe that the differences in leaf margins are not clear-cut. In the absence of a better understanding of the causes of the variation, we conclude that it is currently impossible to recognize meaningful separate taxa even at infraspecific rank, and we maintain the existing broad concept of the species.

Conservation status. – With an “Extent of Occurrence” (EOO) of 436,663 km 2,anda n“Area of Occupancy” (AOO) of 315 km 2, and 29 known subpopulations, seven of which are within protected areas (Ankarafantsika, Ankarana, Bemaraha, Isalo, Loky Manambato, Manongarivo and Forêt de Mikea). It is thus assigned a preliminary status of “Least Concern” [LC].

Figures

Fig. 1. – Distribution of Rotheca microphylla (Blume) Callm. & Phillipson (triangles) and Rotheca mirabilis (Baker) Callm. & Phillipson (stars) in Madagascar mapped on the biogeographic zones of CORNET (1974).

Fig. 2. – Living plant of Rotheca microphylla (Blume) Callm. & Phillipson. [Photo: J. Bosser]