Bacopa hirsuta (Hassl.) Descole & Borsini (1954: 139)

Sosa, María De Las Mercedes, Moroni, Pablo & O’Leary, Nataly, 2018, A taxonomic revision of the genus Bacopa (Gratioleae, Plantaginaceae) in Argentina, Phytotaxa 336 (1), pp. 1-27 : 4-6

2. Bacopa congesta Chodat & Hassler (1904: 289) . Fig. 2 .

≡ Bacopa paraguariensis subsp. congesta (Chodat & Hassl.) Hassler (1917: 13) .

Type:— PARAGUAY. Tucanguá, E. Hassler 3836 (lectotype G!, four sheets [first-step designated by Souza & Giulietti 2009: 30], second-step lectotype G 00229867! [designated here]; isolectotypes BM 000098479!, G 00229864!, G 00229865!, G 00229866!, MPU 020756!, NY 00067872!, P 00753795!) .

= Bacopa congesta var. hirsuta Hassler (1912: 348) ≡ Bacopa paraguariensis var. hirsuta (Hassl.) Hassler (1917: 13) ≡ Bacopa hirsuta (Hassl.) Descole & Borsini (1954: 139) , syn. nov.

Type:— PARAGUAY. Sierra de Amambay en pantanos cerca de Estrella, T. Rojas (Herb. Hassler 10207) (lectotype G 00229869! [designated here], isolectotypes G 00229868!, G 00229870!, G 00229871!, K 000533463!).

Herbs, biannual or perennial, 30–100 cm tall, erect, branched towards the apex, stems densely hispid with scabrid hairs. Leaves opposite, sessile, blade narrow ovate, 23–50 × 5–10 mm, apex acute, base amplexicaul, margin entire or slightly serrate, densely hispid with scabrid hairs on both surfaces. Flowers arranged in terminal racemose inflorescences, foliaceous, pedicels hispid, 4.8–5 mm long, bracteoles two, linear, 2–3 mm long, hispid. Calyx 5-lobed, the external dorsal lobe elliptic, 5.8–6 × 2–2.2 mm, apex acute, base truncate, the two lateral lobes ovate, 3.8–4 × 1.8–2 mm, apex acute, base truncate, notoriously nerved and densely hispid with scabrid hairs, the two internal lobes linear, 1.8–2 × 0.4–0.5 mm, apex acute, densely hispid. Corolla orange, pink or red color, tube 8–10 mm long, slightly puberulous; stamens 4; ovary glabrous, style bifid, stigmatic apex smooth. Capsule ovoid, apex acute, 3.8–4 × 2.8–3 mm.

Distribution and habitat:—Native to South America, it is found in southern Brazil, Paraguay and northeastern Argentina. It grows between sea level and 800 m elev., in wet lands and flood plains.

Nomeclatural remarks:— Bacopa congesta was described from material collected by E. Hassler in Paraguay. Souza & Giulietti (2009) designated the Hassler material at G as lectotype. However, four sheets were found there, and therefore the statement of the authors must be considered as a first-step typification. In order to narrow this designation the most complete specimen is here selected as second-step lectotype (Art. 9.17 ICN, McNeill et al. 2012, McNeill 2014).

Bacopa congesta var. hirsuta ( Hassler 1912) was described from material collected by T. Rojas in Paraguay. Four sheets belonging to the collection T. Rojas (Herb. Hassler 10207) were found at G, where Hassler collections from Paraguay are kept ( Stafleu & Cowan 1979). Thus, the specimen showing the best quality of preservation of the important diagnostic features of the taxon is here chosen as lectotype of the name (Art. 9.17).

Taxonomic remarks:— Hassler (1912) establishes the variety B. congesta var. hirsuta differentiating it from the type variety because of its much branched stem, its hirsute-tomentose pubescence in stems and scabrid bracteoles, and its corolla tube almost 10 mm long. Descole & Borsini (1954), later followed by Zuloaga et al. (2008), consider both taxa as different species based on different pedicel lengths and insertion of the calyx lobes: B. congesta and B. hirsuta (Hassl.) Descole & Borsini. The study of numerous herbarium specimens (see Appendix 2), together with the type materials, evidence it is not possible to differentiate neither varieties nor different species within the taxonomical concept of B. congesta , so B. congesta var. hirsuta is here considered a synonym of the type variety.

Selected specimens examined:— Corrientes: Ituzaingó, Estancia Santa Rita, 6 Mar 1987, Krapovickas et al. 41232 (CTES, LIL). Misiones: Capital, Bañado de Arroyo Caimán, 16 Nov 1994, Lirussi et al. 586 (CTES).

Figures

FIGURE 2. Bacopa congesta. A. Plant aspect. B. Detail of node with two leaves. C. Detail of stem pubescence. D. Detail of leaf pubescence, adaxial surface.E. Detail of leaf pubescence, abaxial surface.F. Flower. G. Corolla opened, showing stamens. H. Gynoecium. I. Calyx. J. Bracteoles. K. Dorsal lobe, external view. L & M. Lateral lobes, external views. N & O. Internal lobes. P. Capsule (from Pedersen 12399, CTES).