In a recent publication (Hazzi and Hormiga 2021) we demonstrated that there are two species under the name of the ctenid spider Phoneutria boliviensis (F.O. Pickard-Cambridge, 1897) and used the name Phoneutria depilata (Strand, 1909) for this second species, which in the past had been treated as a junior synonym of boliviensis. We proposed that “Ctenus peregrinoides Strand, 1910” was a new junior synonym of Phoneutria depilata. We note here that such synonymy is an error. The problem resides in the fact that the name “Ctenus peregrinoides” is not available based on the Criteria of Availability of the ICZN (1999), of which Articles 10 and 11–20 must be satisfied. Article 11.5 states that: “Names to be used as valid when proposed. To be available, a name must be used as valid for a taxon when proposed, unless it was first published as a junior synonym and subsequently made available under the provisions of Article 11.6.1” (ICZN 1999). This requirement is not satisfied by Strand’s provisional name “C. peregrinoides.” Strand (1909a: 318) described two females from Guatemala under the name Ctenus peregrinus F.O. Pickard-Cambridge, 1900, and noted some differences with Pickard-Cambridge’s illustration of peregrinus in ‘Biologia Centrali Americana’, stating that “Sollte die Art neu sein, möge sie peregrinoides m. genannt warden” (“If the species is new, it may be called peregrinoides”). Thus, Strand did not use the name “Ctenus peregrinoides” as valid when he proposed it (valid as opposed to, for example, “if this were a new species, here is a name”), which means that his provisional name is not available for nomenclatural purposes. Formally treating “peregrinoides” as a junior synonym is inconsequential because Strand’s name is not available in a nomenclatural sense.

Furthermore, we need to correct the exact publication dates of the two relevant works of Strand (1909a, b). The unavailable name “peregrinoides” was published on 21 October,1909. A couple of months later (21 December 1909) Strand described Ctenus depilatus. The fact that these two publications appeared both in the 28^th issue of Zoologische Jahrbücher, Abteilung für Systematik, Geographie und Biologie der Tiere, which corresponded to 1910 (as printed in the frontispiece of the journal), has been a source of confusion regarding the publication dates. While Roewer (1955: 649 for C. depilatus; 654 for C. peregrinus) correctly lists both of them as published in 1909, the catalogs of Petrunkevitch (1911: 413, 476) and Bonnet (1956: 1279, 1287) list them as published in 1910.

We would like to thank Theo Blick for pointing out the exact dates of Embrik Strand’s publications. N. Hazzi was supported by a Fulbright-Colciencias scholarship and the Office of Graduate Student Assistantships and Fellowships of The George Washington University. Additional support was provided by a US National Science Foundation grant (DEB 1754289) to GH.