Heterozoanthus Verrill, 1870

Low, Martyn E. Y. & Reimer, James Davis, 2012, Zoanthid housekeeping: some nomenclatural notes on the Zoantharia (Cnidaria: Anthozoa: Hexacorallia), Zootaxa 3485, pp. 83-88 : 83-84

Heterozoanthus Verrill, 1870 (nomen oblitum), and Heterozoanthidae Pax & Müller, 1956 , objective synonyms of Parazoanthus Haddon & Shackleton, 1891 (nomen protectum), and Parazoanthidae Delage & Hérouard, 1901 : reversal of precedence

Verrill (1870: 371) established the genus-group name Heterozoanthus with the inclusion of three species— Palythoa axinellae Schmidt, 1862 , Parazoanthus swiftii Duchassaing & Michelotti, 1860 , and the new species Heterozoanthus scandens . No type species was designated. Palythoa axinellae Schmidt, 1862 , and Parazoanthu swiftii Duchassaing & Michelotti, 1860 , are now assigned to the genus Parazoanthus Haddon & Shackleton, 1891 , the former the type species by original designation (Low & Reimer 2011: 64; Pax & Müller 1956: 2). The name Heterozoanthus scandens Verrill, 1870 , has not been treated taxonomically since it was first described.

Pax & Müller (1956: 2) considered Heterozoanthus Verrill, 1870 , to be a synonym of Parazoanthus Haddon & Shackelton, 1891 , and showed that the name Heterozoanthus Verrill, 1870 , had not been used as a valid name in over 50 years and enacted the “ Loi de conservation adoptée par le XIV me Congrès International de Zoologie à Copenhagen (1953) ”. This “ Loi de conservation ” was a draft proposal for the conservation of a junior synonym (or homonym) in current usage when it was found that the senior synonym (or homonym) had not been used for 50 years or more (Mayr et al. 1953). This so-called “50-year rule” only came into force in the first edition of the Code (ICZN 1961: 23). Therefore, the action of Pax & Müller (1956: 2) is not valid.

We designate Palythoa axinellae Schmidt, 1862 , as the type species of Heterozoanthus Verrill, 1870 , thereby making this genus-group name a junior objective synonym of Parazoanthus Haddon & Shackleton, 1891 , as they have the same type species (Article 61.3.3 of the Code).

The Principle of Priority (Article 23 of the Code) requires that the oldest available name for the taxon under consideration is to be used. However, replacing Parazoanthus Haddon & Shackleton, 1891 , with Heterozoanthus Verrill, 1870 , is not in the interest of nomenclatural stability, as recognised by Pax & Müller (1956). We invoke Article 23.9 of the Code that requires a reversal of precedence of a junior synonym when the senior synonym has not been used as a valid name after 1899 (Article 23.9.1.1) and the junior synonym “has been used for a particular taxon, as its presumed valid name, in at least 25 works, published by at least 10 authors in the immediately preceding 50 years and encompassing a span of not less than 10 years” (Article 23.9.1.2).

Since 1899, the genus-group name Heterozoanthus Verrill, 1870 , has only been used in two nomenclators (see Pax & Müller 1956: 2), which do not constitute valid usage on their own (Article 23.9.6 of the Code), thus fulfilling Article 23.9.1.1 of the Code. Low & Reimer (2011a: 67, 68) cited 30 publications by 69 different authors in the last 33 years using Parazoanthus Haddon & Shackleton, 1891 , as a valid name to fulfil Article 23.9.1.2 of the Code to reverse precedence of Bergia Duchassaing & Michelotti, 1860 , and Parazoanthus Haddon & Shackleton, 1891 .

As both requirements of Article 23.9.1 are met, and in accordance with Article 23.9.2, the name Parazoanthus Haddon & Shackleton, 1891 , is considered the valid name and takes precedence over Heterozoanthus Verrill, 1870 . Parazoanthus Haddon & Shackleton, 1891 , now becomes a nomen protectum and Heterozoanthus Verrill, 1870 , a nomen oblitum.

The “ Heterozoanthidae ” (based on Heterozoanthus ) appears to have been inadvertently established by Pax & Müller (1956: 2) in their discussion of the family Parazoanthidae Delage & Hérouard, 1901 (based on Parazoanthus ). The authorship of the family-group name Heterozoanthidae should thus be attributed to Pax & Müller (1956: 2). As both family-group names are based on type genera that are objective synonyms, Heterozoanthidae Pax & Müller, 1956 , and Parazoanthidae Delage & Hérouard, 1901 , are objective synonyms (Article 61.3.2 of the Code). This family-group synonymy does not cause any problems as Parazoanthidae Delage & Hérouard, 1901 —which is in current and widespread use (see Low & Reimer 2011a)—has priority over Heterozoanthidae Pax & Müller, 1956 .