Nomenclatural checklist for Acromegalomma species (Annelida, Sabellidae), a nomen novum replacement for the junior homonym Megalomma Johansson, 1926

Abstract Acromegalomma, nomen novum, is introduced as a replacement name for the polychaete genus Megalomma Johansson, 1926 (Annelida, Sabellidae), preoccupied by Megalomma Westwood, 1842 (Insecta, Coleoptera, Carabidae). The historical background of the homonymy and a full list with 36 new combinations in the new genus are included, while two species are considered as species inquirenda.


Introduction
The genus Megalomma (Annelida, Sabellidae) was established by Johansson (1926) for the usage of Branchiomma sensu Claparède (1869), based on the species Branchiomma koellikeri Claparède, 1869. However, the name Megalomma is preoccupied by Megalomma Westwood, 1842 (Insecta, Coleoptera), a well-established genus of tiger beetles from the Mascarene Islands. Megalomma Johansson, 1926 has no known available or potentially valid synonyms, for which reason, and in accordance with Article 60.3 of the ICZN (1999), it must be replaced by a new substitute name.
A second genus Megalomma was created by Smith (1873: 405) in Hymenoptera (Insecta), to include three new species from Brazil: Megalomma politum Smith, 1873, M. elegans Smith, 1873, and M. nigriceps Smith, 1873. Later Schulz (1906 pointed that it was a junior homonym of Megalomma Westwood, 1842 and replaced it by the new name Megistommum Schulz, 1906. In polychaetes, the name Megalomma was first used by Johansson (1926: 10), as a replacement name for Branchiomma sensu Claparède (1869), based on a misinterpretation of Claparède's work. While discussing the validity of the name Dasychone introduced by Sars (1862) for sabellids with eyes on their radioles, Claparède (1869) stated that Kölliker (1858) had already used the name Branchiomma for the same group, to include Amphitrite bombyx Dalyell, 1853(renamed as Branchiomma dalyellii Kölliker, 1858. However, instead of synonymizing the junior Dasychone into Branchiomma, Claparède (1869: 162) Dalyell, 1853 to Dasychone (see Claparède 1869: 168), while making reference to a short comment by Kölliker (1858: 536) where he recorded that he had observed, but not named nor described in detail, an additional sabellid from Naples with eight compound eyes near the tips of the radioles: Apparently Claparède's intention was simply to redefine the genus Branchiomma to restrict it to the unnamed Kölliker species (= B. koellikeri Claparède, 1869, the intended new type species of the redefined genus), as can be inferred by the fact that he wrote "Genre Branchiomma Koellkr. char. em." (Claparède 1869: 162).
However, Johansson (1926: 10) considered erroneously that Claparède was formally establishing a new genus, an interpretation that was followed by other authors (e.g. Hartman 1959, Day 1967, Fauchald 1977. In this way, Johansson (1926: 10) argued that the generic name Branchiomma sensu Claparède (1869), used for Branchiomma koellikeri, could not be accepted, as it was already preoccupied by Kölliker (1858)  However, and as stated above, the name Megalomma Johansson, 1926 is itself preoccupied by Megalomma Westwood, 1842, and a replacement name is necessary. The name Acromegalomma, nomen novum is here proposed to accomplish this need.

Material and methods
To establish the list of new combinations in Acromegalomma new name a list of valid Megalomma species was compiled based on WoRMS (Bellan 2008), and updated with Tovar-Hernández and Carrera-Parra (2011), Mikac et al. (2013), Capa and Murray (2015) and Giangrande et al. (2015). Synonymies were obtained from Tovar-Hernández and Carrera-Parra (2011). The type of synonymy and its author are provided inside square brackets, following the synonym. Each new combination is accompanied by the reference of the original description, synonymies, type locality of the species and remarks, when necessary. Type locality is based on the original description, except where indicated. Geolocations of type localities are derived from the original descriptions, being considered an "original geolocation" when the authors provided the coordinates, or "estimated geolocation", when estimated using Google Earth (www.google.com/earth) from the general geographic limits described by the authors. All geolocations were converted to decimal degrees.
The whereabouts of type material of the new combinations were summarised by Tovar-Hernández and Carrera-Parra (2011) and following publications describing new species (Mikac et al. 2013, Capa and Murray 2015, Giangrande et al. 2015. While the gender of Megalomma and Acromegalomma new name is neuter, some names in Megalomma had incorrect endings and needed to be emended. Following Article 31.2 of the ICZN (1999), the names of the new combinations and the species inquirenda were herein revised to assure they agreed in gender with the generic name with which they are combined. Original names with incorrect endings are indicated with the remark "[sic]" following the specific epithet. Endings corrected herein are: carunculatum for carunculata, inflatum for inflata, interruptum for interrupta, jubatum for jubata, and longoventrale for longoventralis.  Johansson (1926). Type material. Following his principle of basing observations and descriptions only on live organisms Édouard Claparède did not designate type material or deposit specimens in museums or collections (Fauchald 1989). However, Knight-Jones (1997) refers the existence of a type of Branchiomma koellikeri Claparède, 1869 deposited at the Zoological Museum of Berlin (currently the Museum für Naturkunde Berlin), with the reference number ZMB 6387. Tovar-Hernández and Carrera-Parra (2011) refer this specimen as being a syntype. Although the designation of a lectotype for B. koellikeri is desirable, it is out of the scope of the present work.

Systematics
Etymology. The name of the new genus is composed by combining the Greek terms for acro, meaning "tip end" or "extremity of a body", mega, meaning "big" or "large", and the suffix -omma, a noun meaning "eye", and referring to the big compound eyes located on the radiolar subdistal region, typical of the genus.
Gender. Neuter. Remarks. The publication date of the genus Megalomma Johansson should be considered as "1926". It was generally accepted as being "1927" until Tovar-Hernández and Salazar-Vallejo (2008) pointed out that the name had been introduced in a previous publication by the same author, referring the date as "1925". In fact, the last page of this publication states "Tryckt den 5 november 1925" ("Printed the 5 November 1925") and in the following line "Uppsala 1925. Almquist & Wiksells Boktryckeri-A.-B." This date is also present in existing reprints of the paper. However, the bounded volume comprising the article provides the publication date as "Häfte 2 inneh. Remarks. The type locality of the species was first stated as being "probably Singapore" ("wahrscheinlich von Singapore"; Grube 1878: vii), and later in the same publication, as "Philippines" ("Von den Philippinen"; Grube 1878: 258). ( (Gravier 1906: 39) and again in 1908 (Gravier 1908b: 91). This caused some confusion, inducing some authors in error, by considering the correct publication date as being 1908, while overlooking the smaller 1906 publication (e.g. Tovar-Hernández and Carrera-Parra 2011). The correct publication date is therefore "1906" (see also Wehe and Fiege 2002).  Capa and Murray 2009: 210-212, figs 2J-M, 4E-F, 5B, 7, 8. Type locality. One Tree Island, Queensland, Australia (-23.5°, 152.0833°; original geolocation). ( Giangrande and Licciano (2008)].
Remarks. Branchiomma vigilans was described on the basis of three specimens from the Gulf of Naples, all of them found with their muddy tubes inserted among the dorsal chaetae of individuals of Aphrodita aculeata Linnaeus, 1758(Claparède 1870. Afterwards the species was recorded on only a couple of occasions in the Western Mediterranean, first by Marion (1876), in the Gulf of Marseille and from 60-65 m (no habitat details), and later by Soulier (1903), who observed about ten specimens collected off Séte (Gulf of Aigues-Mortes) among the chaetae of A. aculeata specimens. Rioja (1923) attributed an empty sandy tube found among the dorsal chaetae of an A. aculeata collected in the region of Valencia to this species, but this record is very dubious, as not only was the worm not present but also the nature of the tube differed from that described by Claparède (1870). Moreover, no type material of B. vigilans is known to exist (Knight-Jones 1997, Giangrande and Licciano 2008, Tovar-Hernández and Carrera-Parra 2011) as Claparède normally did not deposit specimens in museums or collections (Fauchald 1989).
The species was transferred to Megalomma by Hartman (1959: 550), creating a junior secondary homonym of the tiger beetle Megalomma vigilans (Westwood, 1842) (see above), and has since remained a poorly known but valid taxon (Knight-Jones 1997, Tovar-Hernández andSalazar-Vallejo 2008). Giangrande and Licciano (2008) considered the species as being quite rare, probably due to its peculiar habitat, and in spite of stating that its real status needed confirmation, they also observed that it was likely a valid species. However, the species was subsequently omitted from the discussions on new Mediterranean species of Megalomma by Mikac et al. (2013) and Giangrande et al. (2015). The most recent reference to the species seems to be by Tovar-Hernández and Carrera-Parra (2011: 5), who wrote: Megalomma vigilans (Claparède, 1870) was originally found as an epibiont of the sea mouse Aphrodita aculeata Linnaeus, 1758, in the Mediterranean Sea, however, no new records of this association exist. [...] In the case of M. vigilans, the description is poor, the type is lost and there are no additional records.
The described habitat of Megalomma vigilans is unusual, and there are no references of similar cases in the family Sabellidae. It is possible that the habitat is an artefact resulting from the collection process, and that the presence of the species on individuals of Aphrodita aculeata was the consequence of the rough treatment and mixing suffered by the biological material collected by grabs and trawls, or even during the processing of the samples. So, the presence of M. vigilans on A. aculeata could be a post-collection phenomenon, and not the natural habitat of the worm. It is difficult or even impossible to know if the records by Marion (1876) and Soulier (1903) refer to the same species as that collected and described by Claparède (1870) without studying the material, if still existing. There is a possibility that M. vigilans is not as uncommon as it seems, but that for some reason it has not been collected or recognised. For the time being, M. vigilans is here considered as a species inquirenda.
Remarks. According to Fitzhugh (2002), Megalomma pacificum Johansson, 1927 probably belongs to the genus Demonax Kinberg, 1867 (a name recently replaced by Parasabella Bush, 1905 due to homonymy; see Tovar-Hernández and Harris 2010). The fact that the holotype has dried out (Knight-Jones 1997) and that the species has a remote type locality have likely prevented a formal redescription. The species was not included in the Parasabella species list given by Tovar-Hernández and Harris (2010), but its possible inclusion in Parasabella has been implicitly accepted by subsequent authors Murray 2009, Tovar-Hernández andCarrera-Parra 2011).