Sesuvium portulacastrum subsp. portulacastrum

Sukhorukov, Alexander P., Nilova, Maya V., Erst, Andrey S., Kushunina, Maria, Baider, Claudia, Verloove, Filip, Salas-Pascual, Marcos, Belyaeva, Irina V., Krinitsina, Anastasiya A., Bruyns, Peter V. & Klak, Cornelia, 2018, Diagnostics, taxonomy, nomenclature and distribution of perennial Sesuvium (Aizoaceae) in Africa, PhytoKeys 92, pp. 45-88 : 64-66

Sesuvium portulacastrum subsp. portulacastrum Fig. 13

Sesuvium portulacastrum portulacastrum = Sesuvium brevifolium Schumach. & Thonn. in Schumacher, Beskr. Guin. Pl.: 233 (1827).

Lectotype

(designated here by Sukhorukov): Danish Gold Coast, Guinea [probably SE Ghana], P.E. Isert s.n. (C10004542! [photo seen]).

The lectotype is chosen due to inclusion of two elements in the protologue ( Schumacher 1827), a specimen cited and a drawing (Table 216, Fig. 1).

Taxonomic notes.

The autonymous subspecies is of American origin and is known in many parts of tropical Africa and other continents, especially in regions with a hot and humid climate. According to the lectotypification undertaken by Wijnands (1983), the “true” S. portulacastrum is present in Central America (including the Caribbean Islands). The following characters distinguish this subspecies: rampant ramification, glabrous stems and adult leaves with mamillate epidermis, petioles up to 3 mm, oblong-spatulate leaves of 20-60 × 5-10(12) mm and 1.5-4 mm thick, conspicuous (7-12 mm) pedicels, flowers 10-15 mm in diameter and slightly elongated seeds. This description makes sense, because the species is non-uniform in its morphological characters (e.g. leaf length, presence of papillae on stems and leaves, seed ornamentation) and is corroborated by the molecular phylogeny ( Bohley et al. 2017). Although S. portulacastrum is considered to have numerous synonyms ( Bohley et al. 2017), at least some of them need further studies due to the presence of morphological differences, e.g. S. microphyllum Willd. (Caribbean Islands), S. sessile Pers. (South America?) or populations growing in Southeast Asia. In addition, Sesuvium is represented in Central America by at least six taxa (Sukhorukov et al., in prep.) and two of them have to be described as new species.

From humid coastal parts of West Africa, only one perennial species was described, S. brevifolium Schumach. & Thonn. ( Schumacher 1827). This species has spatulate or oblong leaves with very short petioles, the characters being typical of Sesuvium portulacastrum . For this reason, S. brevifolium is merged with S. portulacastrum subsp. portulacastrum , this being in agreement with other accounts ( Hooker 1849, Welwitsch in Oliver 1871, Bohley et al. 2017).

The autonymous subspecies of S. portulacastrum is distributed along the sea shores of many parts of tropical and subtropical Africa ( Exell 1944, Jeffrey 1961, Gonçalves 1979, Gilbert 1993, Friedmann 1994, Sosef et al. 2006, Lisowski 2009, Acebes-Ginovés et al. 2010) and it seems to be present in almost all regions of Africa except South Africa. The causes of such invasion to seashore communities in Africa or in other regions of the Old World are not clear. It can be partially explained by the cultivation of S. portulacastrum in some areas for ornamental purposes, but mostly by transportation of its seeds in the sand ballast of ships sailing between America and other parts of the world in the 15th-17th centuries. The examination of the herbarium specimens indicates that S. portulacastrum was sometimes collected in the same places as native Sesuvium ( S. congense or S. crithmoides ), e.g. on seashores of Kongo-Central province (DR Congo) and Angola.

Additional specimens examined.

ANGOLA: Luanda, Praia do Bispo, Dec 1858, Welwitsch 2385 (BM); [Bengo prov.] Ambriz, [no date] Welwitsch 2383 (K); [Bengo prov.] Dande River, 17 Sep 1955, J. Lebrun 10908 (BR0000013828103); Mossamedes [Namibe], 10 Jan 1956, E.J. Mendes 1250 (BM); [Namibe prov.] Cabo Negro, 15 Apr 1973, P. Bamps et al. 4522 (BR0000013828097, K, LE); Kwanza Sul prov., 10°51'S 13°48'E, 2 Feb 1975, C.J. Ward and J.D. Ward 68 (K); BENIN: Cotonou beach, 22 Mar 1970, L.A. Assi 11134 (G); DEMOCRATIC REPUBLIC OF CONGO: [Kongo Central prov.] Banana, 16 Jul 1915, Bequaert 8014 (BR0000013828165); Bula-Bemba, 2 Sep 1958, J. Wagemans 1982 (BR0000013828172); GABON: Estuaire prov., 22 Feb 1985, A.M. Louis 1728 (BR0000013828028); GHANA: Sekondi, 3 Oct 1925, H. Howes 980 (K); nr Tema harbor, 20 Sep 1960, J.O. Ankrah 20547 (K); Accra, 12 Aug 1958, J. Lebrun 11334 (BR0000013828042); Greater Accra Region, Ambassador Beach, 26 Feb 1977, A.J.M. Leeuwenberg 11123 (BR0000013828035); GUINEA: Conakry, Aug 1954, H. Jacques 7002 (LE); [ Boké Region] Boffa pref., Bel-Air, 5 Feb 1979, S. Lisowski 51828 (BR0000013827567); GLORIOSO ISLANDS: Iles aux Crabes (C. Fontaine, obs.; image seen!); KENYA: Kilifi distr., Malindi, 3 Dec 1961, R. Polhill and S. Paulo 895 (BR0000013828059, K, P04602215); Mikindani distr., Mtwara, 12 Mar 1963, H.M. Richards 17861 (K); Mombasa, 13 Dec 1969, Bally 13736 (G); Tana River distr., Tana delta, Shekiko Camp, 25 Apr 1990, S.A. Robertson 6121 (K); MADAGASCAR: [no exact location and date] herb. Petit-Thouars s.n. (P04600013); MOROCCO: Skhirat, 10 Jun 1937, J. Gattefosse 138 (G, P05196618); MOZAMBIQUE (selected specimens): Delagoa [Maputo] Bay, 1890, H. Junod 258 (G); Komati river, 15 Jul 1922, C.E. Moss 7040 (BM); Lorenço Marques, 31 Aug 1959, R. Watmaugh 313 (M); Maputo, 3 Jun 1970, M.F. Correla and A. Marques 1630 (E00651988); Sofala province, Beira, 26 Feb 1972, M.F. Correla and A. Marques 2812 (M); Maputo, 8 Mar 1979, P.A. Schäfer 6707 (K); Inhambane prov., Massinga, Pomene, 20 Jun 1980, J. de Koning 8197 (WAG1408388); Maganja da Costa, Praia Maraga, 15 Nov 1996, A.R. Torre and M.F. Correia 14693 (BR0000013828134, M); [Massinga distr.] Pomene, 24 Sep 1980, P.C.M. Jansen 7521 (BR0000013828110); SÃO TOMÉ & PRÍNCIPE: São Tomé [Island], Apr 1916, A. Cortesão s.n. (BM); SENEGAL: [Oussouye Dept.] Basse Casamance National Park, Kabrousse, 22 Dec 1976, C. Van den Berghen 1582 (BR0000013827519); [Cap Vert Peninsula] Lake Retba, 20 Dec 1984, D. Thoen 7367 (BR0000013827526); SEYCHELLES: Aldabra Island, 26 Feb 1968, F.R. Fosberg 49547 (L1693568); Aldabra, South Island, Grand Cavalier, 11 May 1972, D. Wood 1686 (E00651983); Farquhar Group, Farquhar Island, 2 Feb 1972, Frazier 121 (K); Farquhar Group, St Pierre Island, 4 Oct 1941, P.O. Wiehe 1681 (MAU 0023813, MAU 0023814); SIERRA-LEONE: Samu chiefdom, 22 Mar 1930, R.R. Glanville 251 (BM, K); SOMALIA: Kodei village, 1°1'S 41°58'E, 29 Jun 1983, J.B. Gillett et al. 5116 (K); SPAIN: Canary Islands (selected specimens): Lanzarote, Playa Honda, 24 Mar 2011, F. Verloove 9276 (BR); La Laja beach, Las Palmas de Gran Canaria, 28°03'38.70"N, 15°25'12.28"W, 31 Jul 2017, M. Salas-Pascual s.n. (MW); Beach of El Águila, San Bartolomé de Tirajana, 27°46°38.80"N, 15°31'38.50"W, 31 Jul 2017, M. Salas-Pascual s.n. (MW); El Veril beach, San Bartolomé de Tirajana, 27°45'36.78"N, 15°33'50.77"W, 31 Jul 2017, M. Salas-Pascual s.n. (BR, MW); Edge of the Charca de Maspalomas, San Bartolomé de Tirajana, 27°44'24.96"N, 15°35'43.79"W, 31 Jul 2017, M. Salas-Pascual s.n. (MW); TANZANIA: Tanga, Tanga Bay, 4 Nov 1929, Greenway 1853 (K); Zanzibar, Marahubi Beach, 22 Apr 1961, H. Faulkner 2814 (BR0000013828073); Dar es Salam, 26 Aug 1968, M. Batty 284 (K); TUNISIA: pers. comm. R. El Mokni (photo!).

General distribution.

The subspecies seems to be widely distributed on the seashores of the tropics, but some populations from tropical America and SE Asia are distinct in their morphological characters. The distribution of Sesuvium portulacastrum subsp. portulacastrum in Africa is presented in Fig. 14 .

Figures

Figure 13. Parts of the plant of Sesuvium portulacastrum subsp. portulacastrum: A vegetative shoots B reproductive shoots. Photographs by M. Salas-Pascual (Gran Canaria, Canary Islands, Spain, July 2017).

Figure 14. Distribution map of Sesuvium ayresii (stars) and S. portulacastrum subsp. portulacastrum (circles, mapped only for Africa).