1. Evolvulus cordatus Moric. (1844: 137).

Lectotype (designated here):— BRAZIL. Piauí: “ Piauhy near Oreias ”, 1839, G. Gardner 2258 (lectotype K000613086 [digital image!], isolectotype BM001122230 [digital image!], F0054787F [digital image!], NY00319007 [digital image!], NY00319006 [digital image!], P04070291 [digital image!], P03545589 [digital image!], P03545586 [digital image!], P03545590 [digital image!], US00111208 [digital image!], W 0062417 [digital image!], W 1889-0011168 [digital image!]

Evolvulus modestus Mart. ex Choisy (1845: 9). First step lectotype designated by Ooststroom 1934 as “type” [M]):— BRAZIL. Bahia: “campis ad fluv. St Franc. prope Joazeiro prov. Bahiensis”, C.F.P. Martius 2279 (Second step lectotype designated here M0184324 [digital image!], isolectotype M0184323 [digital image!]).

Evolvulus bahiensis Helwig (1927: 10). Lectotype (designated here):— BRAZIL. Bahia: Bahia, Taboleiro bei Remanso, 1906, E. Ule 7406 (lectotype L2721423 [digital image!], isolectotype U0003136 [digital image!]).

Notes: — Evolvulus cordatus was established by Moricard (1844) based on collection Gardner 2258 without indicating the herbarium where it was housed. We located 12 sheets distributed in BM, F, K, NY, P, US and in W that represent the original material of E. cordatus in compliance with its protologue. We chose the specimen deposited in K (K000613086; Fig. 1) as the lectotype as it has well-preserved vegetative and reproductive parts, it is in accordance with the author’s taxonomic concept for the species, and it presents handwritten notes.

When Martius (1845) established E. modestus, he only mentioned in the protologue his collection C.F.P. Martius 2279, without indicating the herbarium where it was housed. When Ooststroom (1934) studied Evolvulus for America, he reported that the type collection of E. modestus was deposited in M. Citing the herbarium M and the expression “typus” he effected the lectotypification of the name E. modestus - Art. 7.11 and 9.17 of the ICN (Turland et al. 2018). However, according to Art. 9.17, Ooststroom’s lectotypification must be accepted as the first-step lectotypification, since there are two exsiccates in M that constitute the original material for this name. With that, we designate the specimen deposited in M (M0184324; Fig. 2) as the second-step lectotype because it has more preserved vegetative and reproductive parts.

Evolvulus bahiensis was established by Helwig (1927) based on the collection E. Ule 7406 collected in Bahia state. When he established this species he did not mention any herbarium where the indicated collection would be deposited. We located two exsiccates, one in L, and one in U, that represent the original material of E. bahiensis in compliance with the protologue. We designate the specimen deposited in L (L2721423; Fig. 3) as the lectotype because it has more preserved flowers and fruit.

Morphological relationships and characterization: — Evolvulus cordatus has often been confused with E. ovatus in herbarium collections (e.g. V.M. Cotarelli 1851 HVASF and J.A. Siqueira Filho 2765 HVASF) because they share a decumbent stem with ovate and pilose leaves. However, these species can be easily distinguished by the peduncle length (less than 5 mm long in E. ovatus vs. longer than 5 mm long in E. cordatus) and the diameter of the corolla (up to 4 mm diam. vs. longer than 7 mm diam.).

Distribution and conservation status: — Evolvulus cordatus is endemic to Brazil, where it occurs in the Northeast (Maranh„o, Piauí, Pernambuco and Bahia States) and Southeast regions (Minas Gerais State) growing on sandy and loamy soils on the side of the roads in the Caatinga domain. This species is designated here as Least Concern (LC) due to its EOO estimated at 558, 133.291 km 2. Large populations of this species can be found on roadsides. Populations of this species were found in a protected area (Raso da Catarina Ecological Station, Bahia state).