Article 31

• The date of effective publication is the date on which the printed matter or electronic material became available as defined in Art. 29 and 30. In the absence of proof establishing some other date, the one appearing in the printed matter or electronic material must be accepted as correct.
  • Individual parts of Willdenow’s Species plantarum were published as follows: 1(1), Jun 1797; 1(2), Jul 1798; 2(1), Mar 1799; 2(2), Dec 1799; 3(1), 1800; 3(2), Nov 1802; 3(3), Apr–Dec 1803; 4(1), 1805; 4(2), 1806; these dates are presently accepted as the dates of effective publication (see Stafleu & Cowan in Regnum Veg. 116: 303. 1988).
  • Fries first published Lichenes arctoi in 1860 as an independently paginated preprint, which antedates the identical content published in a journal (Nova Acta Reg. Soc. Sci. Upsal., ser. 3, 3: 103–398. 1861).
  • Diatom Research 2(2) bears the date December 1987. However Williams & Round, the authors of a paper in that issue, stated in a subsequent paper (in Diatom Res. 3: 265. 1988) that the actual date of publication had been 18 February 1988. Under Art. 31.1 their statement is acceptable as proof establishing another date of publication for issue 2(2) of the journal.
  • The paper in which Ceratocystis omanensis Al-Subhi & al. is described was available online in final form on Science Direct on 7 November 2005, but was not effectively published (Art. 29 Note 1). It was distributed in print (in Mycol. Res. 110(2): 237–245) on 7 March 2006, which is the date of effective publication.
• When a publication is issued in parallel as electronic material and printed matter, both must be treated as effectively published on the same date unless the dates of the versions are different as determined by Art. 31.1.
  • The paper in which Solanum baretiae was validly published was placed online in final form, as a PDF document, on 3 January 2012 in the journal PhytoKeys (ISSN 1314-2003). The printed version (ISSN 1314-2011) of the corresponding issue of PhytoKeys, with identical pagination and content, is undated but demonstrably later, as it includes a paper dated 6 January 2012. A correct citation of the name is: S. baretiae Tepe in PhytoKeys 8 (online): 39. 3 Jan 2012.
• When separates from periodicals or other works placed on sale are issued in advance, the date on the separate is accepted as the date of effective publication unless there is evidence that it is erroneous.
  • The names of the Selaginella species published by Hieronymus (in Hedwigia 51: 241–272) were effectively published on 15 October 1911, since the volume in which the paper appeared, though dated 1912, states (p. ii) that the separate appeared on that date.

Recommendation 31A

• The date on which the publisher or publisher’s agent delivers printed matter to one of the usual carriers for distribution to the public should be accepted as its date of effective publication.

Recommendation 31B

• Authors should indicate precisely the dates of publication of their works. In a work appearing in parts the last-published sheet of the volume should indicate the precise dates on which the different fascicles or parts of the volume were published as well as the number of pages and plates in each.

Recommendation 31C

• On reprints of papers published in a periodical, the name of the periodical, volume and part number, original pagination, and date (year, month, and day) should be indicated.