Identities of Corollonema Schltr., Dactylostelma Schltr. and Metoxypetalum Morillo (Apocynaceae: Asclepiadoideae), The

identities of Corollonema Schltr., Dactylostelma Schltr. and Metoxypetalum Morillo (Apocynaceae: Asclepiadoideae), The

Goyder, D J

Summary. Corollonema boliviense Schltr. is synonymous with Oxypetalum brachystemma Malme. The characters used to distinguish Dactylostelma Schltr. and Metoxypetalum Morillo from Oxypetalum R. Br. are not diagnostic, and both genera are placed in synonymy under Oxypetalum. Dactylostelma boliviense Schltr. is transferred to Oxypetalum as O. dactylostelma Goyder. Only one species is recognised in the former Metoxypetalum; this is combined under Oxypetalum as O. retusum (Markgr.) Goyder.

Corollonema Schltr.

The monotypic genus Corollonema Schltr. was based on material collected by Herzog between Macharetí and Buenavista on the western margins of the Bolivian Chaco. Schlechter (1914) cited the position of the corona on the upper part of the corolla tube in erecting his new genus, which he compared to Tweedia Hook. & Arn., Mitostigma Decne. and Oxypetalum R. Br. Morillo (1997) added no new information other than noting the existence in US of a photograph of the destroyed Berlin type. Liede (1997) interpreted the original description as referring most probably to a species of Mitostigma – despite the presence of a corona – but had been unable to locate any type material.

A duplicate of the type of Corollonema boliviense Schltr., Herzog 1180, was discovered recently in Leiden. Examination of this material reveals that C. boliviense is conspecific with Oxypetalum brachystemma Malme. The corona is adnate to the corolla tube for much of its length, but occurs in a position typical of Oxypetalum. Curiously, the species had already been described under Oxypetalum by Schlechter, as O. albiflorum Schltr. (Schlechter 1906). The synonymy is outlined below.

Oxypetalum brachystemma Malme, Ark. Bot. 3 (8): 2 (1904). Type: Argentina, Jujuy, near San Lorenzo, Nov. 1893, Schultz in Kurtz Hb. Argent. 8163 (S lectotype, designated here); original syntype: Bolivia, Tarija, Gran Chaco, Tatarenda, 17 March 1902, Fries 1376 [cited by Malme as 1372] (S).

Oxypetalum albiflorum Schltr., Bot. Jahrb. Syst. 37: 621 (1906). Type: Bolivia, Tanja, O’Connor, Chiquiaca, 1000 m, 6 Feb. 1904, Fiebrig 2699 (B[dagger] holotype; BM, E, K, P isotypes), non O. albiflorum Decne. (1844) – see Malme (1932: 14).

Corollonema boliviense Schltr., Repert. Spec. Nov. Regni Veg. 13: 441 (1914). Type: Bolivia, Chuquisaca, between Machareti and Buenavista, 800 m, Dec. 1910, Herzog 1180 (B[dagger] holotype; L isotype). Synon. nov.

Dactylostelma Schltr.

Dactylostelma Schltr. is a monotypic genus in Asdepiadeae subtribe Oxypetalinae, and was described by Schlechter in 1895. Morillo (1994a) also drew attention to this andean genus. Liede (1997: 236) compared Dactylostelma with Calostigma Decne., a genus currently regarded as synonymous with Oxypetalum in which the stigma head appendages are more dissected than in typical members of Oxypetalum.

Dactylostelma is a twining herb with fleshy white flowers. The mouth of the well-developed corolla tube is obscured by a densely bearded indumentum and the exserted stigma head appendages are conspicuously fleshy and expanded. Enlarged stigma head appendages similar to these are found in some species of Araujia Brot., but are hitherto unknown in Oxypetalum R. Br. although in some species of the former Calostigma they are more expanded than in typical Oxypetalum. In all other respects, most significantly in the form and position of the corona lobes which are adnate to the corolla tube at the base of the gynostegium and free above, the characters exhibited by Dactaylostelma are also found in Oxypetalum. Bearded mouths to the corolla tube are known in several species of Oxypetalum – O. brachystemma Malme and O. erianthum Decne., for example.

The sole diagnostic character possessed by Dactylostelma, the unusual development of the stigma head appendages, is not considered sufficient to maintain the genus as distinct from Oxypetalum, and Dactylostelma boliviense Schltr. is therefore formally transferred to Oxypetalum under the name O. dactylostelma Goyder, as the name O. boliviense is already occupied. Some support for this position comes from a preliminary analysis of trnL-F sequence data (Liede-Schumann et al. in press) where Dactylostelma is nested within a clade consisting principally of species of Oxypetalum.

Oxypetalum dactylostelma Goyder nom. nov.

Dactylostelma boliviens Schltr., Oesterr. Bot. Z. 45: 452 (1895), non Oxypetalum boliviense Schltr., Bol. Jahrb. Syst. 37: 622 (1906). Type: Bolivia, Río Yuntas, 900 m, April 1892, Kuntze s.n. (B[dagger] holotype; NY lectotype, designated by Morillo (1994a)).

DISTRIBUTION AND HABITAT. With the exception of the type collection, all material was collected in moist cloud forest between 1500 -2000 m in the Paractí valley of the Chapare region. Río Yunlas, the type locality listed by Kuntze, is lower down the same valley system. The altitude recorded was 900 m. However, localities recorded by Kuntze are notoriously unreliable, and the details should perhaps be treated with caution.

SPECIMENS EXAMINED. BOLIVIA. Cochabamba, Chapare: 89 km from Cochabamba towards Villa Tunari, 23 Nov. 1981, Heck 7278 (K, LPB); Río Yuntas, April 1892, Kuntze s.n. (NY); near Locotol, 19 Jan. 1929, Steinbach 8844 (LIL); by first stream below Locotol on descent to Chapare, 29 Jan. 1995, Wood 9254 (K, LPB); on ascent from Río Espirito Santo to Locotol, 21 Jan. 1996, Wood 10438 (BOLV, K, LPB); c. 0.5 km above Santa Isabel on road to Paractí, below Cochabamba – Chapare highway, 14 Nov. 1999, Wood 15195 (K, LPB).

Metoxypetalum Morillo

Metoxypetalum Morillo has distinctive flowers with a rotate corolla and five pubescent, truncate corona lobes which arise near the base of the corolla tube and form an overlapping ring in the throat.

Morillo (1994b) correctly observed that the Andean Macroscepis retusa Markgr. was not congeneric with the other species of Macroscepis Kunth – a genus in subtribe Gonolobinae occurring principally at low altitudes in the Amazon basin – and was more closely allied to the Oxypetalum group of genera in subtribe Oxypetalinae. He elected a new genus, Metoxypetalum, for this Peruvian species and described a second species, M. vogelii Morillo, based on a single collection from Bolivia. Metoxypetalum was distinguished from Oxypelalum on the basis of three characters: the shape of the corolla lobes, the form of the stigma head, and the lack of teeth on the translator arms of the pollinarium. These characters are examined in turn below.

The corolla lobes of Meloxypetalum are broadly ovate to deltoid, and only barely contorted. This contrasts with the vast majority of species in Oxypetalum where the corolla lobes are typically oblong or narrowly triangular and strongly contorted. Some collections of O. molle Hook. & Arn., however, have broadly ovate corolla lobes.

The top of the stigma head in Metoxypetalum is only barely exserted from the stamens, and is convex apically with two short mucros in the centre, rather than rostrate, bilobed and well-exserted from the stamens as in most species of Oxypetalum. This character is not unique, however, as can be observed by examining illustrations of Brazilian Oxypetalum presented by Hoehne (1916). For example, O. pachyglossum Decne. (t. I fig. 1 & 2 as O. coriaceum Decne.), O. malmei Hoehne (as O. subcapitatum Malme, t. XII Hg. 4), O. dusenii Malme (t. X fig. 4), O. sublanatum Malme (t. VII fig. 2) and O. pilosum Gardn. (as O. pauperculum E. Fourn., t. V fig. 4) all have poorly developed stigma head appendages, but are clearly members of Oxypetalum on the basis of other characters. Comparable variation in the form of stigma head appendages has recently been discussed in the related genus Philibertia Kunth (Goyder in press).

The third character used by Morillo to support the erection of Metoxypetalum was the absence of teeth on the translator arms of the pollinarium. However, several species of Oxypetalum lack such teeth (Hoehne 1916 t. I fig. 3 – O. alpinum (Vell.) Fontella & Schwarz (as O. umbellatum Gardn.); O. macrolepis Decne. (t. I fig. 4); O. erianthum (t. 2 fig. 2); O. urbanianum A. Silv. (t. 2 fig. 3); O. martii E. Fourn. (t. IX fig. 4; t. X figs. 1 & 2)). This character is clearly not diagnostic at generic level. Other parts of the pollinarium in Metoxypetalum, such as the form of the corpusculum, are typical of Oxypetalum.

It is clear from the discussion above, that Metoxypetalum cannot be maintained as a distinct genus and should be subsumed within Oxypetalum.

Morillo (1994b) recognised two species, Metoxypetalum retusum (Markgr.) Morillo from Peru and M. vogelii Morillo from Bolivia, citing differences in the dimensions of floral organs of the two collections known at the time. Additional collections have been made since then from northern Peru and from two valley systems in northern Bolivia, suggesting that the distribution of these taxa is both more extensive and less disjunct than implied by the earlier records. The rather limited morphological variation observed in the material now available supports the recognition of a single taxon, rather than the two recognised by Morillo. The formal transfer to Oxypetalum, and the synonymy of the single species recognised are presented below.

Oxypetalum retusum (Markgr.) Goyder comb. nov.

Macroscepis retusa Markgr., Notizbl. Bot. Gart, Berlin-Dahlem 11: 787 (1033). Type: Peru, Ruiz & Pavón 5/95 (MA lectotype, designated by Morillo (1994b); BM, F isolectotypes).

Metoxypetalum retusum (Markgr.) Morillo, Ernstia 3: 146 (1994).

Metoxypetalum vogelii Morillo, Ernstia 3: 147 (1094). Type: Bolivia, Santa Cruz, Caballero, near Fortaleza between Siberia and Gomarapa, 15 Jan. 1965, Vogel 505 (WU holotype – see note below). Synon. nov.

DISTRIBUTION AND HABITAT. Found in scattered localities from northern Peru to the bend in the Andes in central Bolivia, generally in disturbed or degraded cloud forest remnants. Recorded altitudes range from 1800 m in Peru and c. 2300 – 2600 m in Bolivia. This species occurs at higher altitude than most species of Oxypetalum, which is most diverse in central and eastern Brazil, but is not unique in this respect.

NOTES. Vogel’s private herbarium was donated to WU (Vogel, pers. comm.) – Morillo (1994b) reported incorrectly that Vogel 505, the type of M. vogelii, had been deposited in MJG.

The corolla varies from brown to purple; the corona is dull green or brown.

SPECIMENS EXAMINED. PERU. Cajamarca: Santa Cruz, 3 km ENE of Monteseco, 1 June 1987, Santisteban & Guevara 127 (MO); Huanuco: sin loc., Ruiz & Pavón 5/95 (BM). BOLIVIA. La Paz, Saavedra: 11 km from Charaxani on road to Apolo, 11 Feb. 2003, Wood et al. 19038 (K., LPB); below Charazani on road to Apolo, 2 Nov. 2003, Wood et al. 19781 (K, LPB); Cochabamba, Chapare: road from Corani Pampa to Rancho Masaj Llajta above the Rio Gorani, 9 Dec. 1995, Ritter & Wood 2719 (BOLV); 5 km beyond Gorani Pampa, 15 km off Cochabamba – Ghapare highway, 9 Dec. 1995, Wood 10221 (BOLV, K, LPB); Santa Cruz, Caballero: near Fortaleza between Siberia and Gomarapa, 15 Jan. 1965, Vogel 505 (WU).

Acknowledgements

I am most grateful to Dick Brummitt and Tatiana Konno for valuable nomenclatural advice, and to the curators of the various herbaria listed for access to their collections.

References

Goyder, D. J. (in press). Four new species of Philibertia Kunth (Apocynaceae: subfam. Asclepiadoideae), and an amplified concept of the genus. Kew Bull.

Hoehne, F. C. (1916). Monographia das Asclepiadaceas Brasileiras (Monographia Asclepiadaccarum Brasiliensium), ou, Rclação e descripção das Asclepiadaceas brasileiras encontradas nos diverses herbarios do Brasil. Comissão de Linhas Telegráficas Estratégicas de Mato Grosso ao Amazonas. No. 38. Fasc. 1. Oxypetalum; Fasc. 2. Calostigmn.

Liede, S. (1997). Subtribes and genera of the tribe Asdepiadeae (Apocynaceae, Asdepiadoideae) – a synopsis. Taxon 46: 233 – 247.

Liede-Schumann, S., Rapini, A., Goyder, D. J. & Chase, M. (in press). Phylogenetics of the New World subtribes of Asdepiadeae. (Apocynaceae-Asdepiadoideae): Metastelmalinae, Oxypetalinae and Gonolobinae. Syst. Bot.

Malme, G. O. A. (1932). Asclepiadaceae austroamericanae praecipue andinae. Ark. Bot. 25A (7): 1 – 26.

Morillo, G. (1994a). Fontellaea, gen. nov., y otras novedades o aportaciones en Asclepiadaceae, andinas. Anales Jard. Bot. Madrid 52: 33 – 41.

_____ (1994b). Metoxypetalum Morillo, gen. nov. y especies nuevas o interesantes en Ditassa R. Br. y Macroscepis H. B. K. Ernstia 3: 143 – 150.

_____ (1997). Asclepiadaceae neotropicales nuevas o poco conocidas. Acta Bot. Venez. 20 (2): 11 – 23.

Schlechter, R. (1895). Asclepiadacaeae Kuntzeanae. Oesterr. Bot. Z. 45: 449 – 454.

_____ (1906). Asdepiadacene, andinae. Bot. Jahrb. Syst. 37: 601 – 627.

_____ (1914). Asclepiadaceae novae bolivienses Herzogianae. Repert. Spec. Nov. Regni Veg. 13: 438 – 443.

D. J. Goyder1

Accepted for publication June 2004.

1 Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, U.K.

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