Elevation of Pseudoskusea, Rusticoidus and Protomacleaya to valid subgenera in the mosquito genus Aedes based on taxon naming criteria recently applied to other members of the Tribe Aedini (Diptera: Culicidae)

Background

Pseudoskusea, Rusticoidus and Protomacleaya were well-recognized, morphologically distinct subgenera within the genus Aedes prior to a series of taxonomic changes over the past 15 years by Reinert, Harbach and Kitching, when they were recognized as subgenera of the genus Ochlerotatus. In our recent effort to stabilize the Tribe Aedini, we synonymized these subgenera and associated species back into the genus Aedes, but incorrectly assigned them as putative informal groups, instead of reinstating them to subgenera.

Conclusion

Here we formally elevate three traditionally recognized subgenera (Pseudoskusea, Rusticoidus and Protomacleaya) within the genus Aedes.

The tribe Aedini is comprised of about a third of all recognized mosquito species, and includes many vectors of debilitating viral diseases to humans, such as Dengue and Chikungunya. Within the tribe, the genus Aedes, in the traditional sense, is the largest genus in the tribe with 932 species. Other aedine genera are Armigeres, Eretmapodites, Haemagogus, Heizmannia, Opifex, Psorophora, Udaya and Verrallina. During the past 11 years, based on a series of morphological phylogenetic studies by Reinert, Harbach & Kitching (RH&K) [1–4], and the taxonomic actions resulting from those studies, the original genus Aedes was split into 74 genera, reducing the genus Aedes from over 900 species [5–8], to only 12. Chief among the reasons given by RH&K to elevate so many genera was the author’s claim of an unreferenced “principle of equivalent rank.” This implied that if traditionally accepted genera were phylogenetically co-equal with other clusters of species in their analyses, the newly recognized groups should also be given similar taxonomic status. These taxonomic actions were highly controversial [9, 10] and resulted in wide-spread confusion about which names to apply to most vectors of disease organisms in genus Aedes (see Table one in [12]). For example, during this period, Aedes japonicus (Theobald), an invasive species and proven vector of West Nile virus and Cache Valley virus, was known variously as Aedes (Finlaya) japonicus [5], Ochlerotatus (Finlaya) japonicus [11], ‘Ochlerotatus’ (‘Finlaya’) japonicus [1] and Hulecoeteomyia japonica [2].

Close scrutiny of the RH&K phylogenetic results and a reanalysis of their dataset led Wilkerson et al. [12] to the conclusion that based on the evidence provided by RH&K the classification changes they promoted and that resulted in the split of the well-known genus Aedes into so many genera, were not warranted. Aedes was therefore reinstated [12], but to preserve their phylogenetic hypotheses the RH&K genera were reduced in rank to subgenera of Aedes. Any subgenera in the fragmented RH&K system were reduced to putative informal group status [12]. Rationalization for reinstatement of genus Aedes to include all “traditionally” accepted species was based on opinions promoting a conservative approach to classification change based on new phylogenetic analyses [13–15]. These opinions were comprehensively solidified by Vences et al. [16] who, in detail, discussed the relationship between nomenclatorial utility and phylogenetic accuracy. As a guide to determine the suitability for classification changes they proposed a number of Taxon Naming Criteria (TNCs). Appropriate TNCs were cited to reinstate the “traditional” species in genus Aedes [12]. Central to these arguments reinstating genus Aedes, while retaining other traditional aedine genera were: TNC 2, Clade Stability; TNC 3, Phenotypic Diagnosibility; TNC 8, Manageability; TNC 10, Nomenclatural Stability, and; TNC 11, Community Consensus. Since, to these authors [12], there was no compelling evidence warranting changing the classification of traditional diagnosable genera, the traditional genera in tribe Aedini should be retained until strong, multiple lines of evidence are produced showing the contrary.

Following our recent publication reinstating the genus Aedes [12], we revisited the above rationale and realized that three traditionally recognized Aedes subgenera (Pseudoskusea, Rusticoidus and Protomacleaya), recognized as subgenera by RH&K in their genus Ochlerotatus, were incorrectly synonymized as putative informal groups [12], when they should have been reinstated as bona fide subgenera of the genus Aedes. All are diagnosable, well-known traditional groupings and should be retained as such. Taxonomic information for each subgenus, including important references and component species are given in Appendix.

Here, we formally retrieve Pseudoskusea, Rusticoidus and Protomacleaya from synonymy within the Aedes subgenus Ochlerotatus [12], and elevate all three as subgenera of the genus Aedes.

We thank Bruce Harrison for careful review of the manuscript and his many helpful comments. This research was performed under a Memorandum of Understanding between the Walter Reed Army Institute of Research and the Smithsonian Institution, with institutional support provided by both organizations. This manuscript was prepared whilst YML held a National Research Council (NRC) Research Associateship Award at the Walter Reed Army Institute of Research. The material to be published reflects the views of the authors and should not be construed to represent those of the U.S. Department of the Army or the U.S. Department of Defense.

Affiliations

1. Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA

   • Richard C. Wilkerson
   •  & Yvonne-Marie Linton

2. Walter Reed Biosystematics Unit, Museum Support Center, Smithsonian Institution, Suitland, Maryland, USA

   • Yvonne-Marie Linton

3. Department of Entomology, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA

   • Yvonne-Marie Linton

4. Faculty of Preventative Medicine and Biometrics, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA

   • Yvonne-Marie Linton

Corresponding author

Correspondence to Richard C. Wilkerson.

Competing interests

The authors declare that they have no competing interests.

Authors’ contributions

RCW and YML contributed equally to the final paper. Both authors read and approved the final version of the manuscript.

Appendix

Taxonomic Catalog Citation

Subgenus Pseudoskusea Theobald 1907 (as genus) [17].

Type species: Skusea multiplex Theobald.

Subgenus Synonym Caenocephalus Taylor 1914 [18] (not Caenocephalus van der Wulp, 1898 [19])

bancroftianus Edwards, 1921

culiciformis (Theobald, 1905)

multiplex (Theobald, 1903)

postspiraculosus Dobrotworsky, 1961

Important References:

Dobrotworsky 1961 (tax., bion.; Australia) [20]

Dobrotworsky 1965 (tax., key, bion.; Australia) [21]

Lee et al. 1984 (tax., key, distr., bion.; Australia) [22]

Reinert 2000 (to subg. of genus Ochlerotatus) [11]

Reinert 2002 (F gen.*) [23]

Reinert et al. 2006 (phyl., class.; to genus) [2]

Reinert et al. 2008 (to subg. of genus Ochlerotatus) [3]

Wilkerson et al. 2015 (phyl., class.; to syn. of subg. Ochlerotatus of genus Aedes) [12]

Herein: to subg. of genus Aedes

Subgenus Protomacleaya Theobald 1907 (as genus) [17].

Type species: Culex trisereatus Say

aitkeni Schick, 1970

alboapicus Schick, 1970

amabilis Schick, 1970

argyrothorax Bonne-Wepster and Bonne, 1920

berlini Schick, 1970

bertrami Schick, 1970

braziliensis Gordon and Evans, 1922

brelandi Zavortink, 1972

buenaventura Schick, 1970

burgeri Zavortink, 1972

campana Schick, 1970

casali Schick, 1970

chionotum Zavortink, 1972

daryi Schick, 1970

diazi Schick, 1970

gabriel Schick, 1970

galindoi Schick, 1970

hendersoni Cockerell, 1918

heteropus Dyar, 1921

homoeopus Dyar, 1922

idanus Schick, 1970

impostor Schick, 1970

insolitus (Coquillett, 1906)

knabi (Coquillett, 1905)

kompi Vargas and Downs, 1950

metoecopus Dyar, 1925

niveoscutum Zavortink, 1972

podographicus Dyar and Knab, 1906

sandrae Zavortink, 1972

schicki Zavortink, 1972

schroederi Schick, 1970

sumidero Schick, 1970

tehuantepec Schick, 1970

terrens (Walker, 1856)

thorntoni Dyar and Knab, 1907

triseriatus (Say, 1823)

vargasi Schick, 1970

zavortinki Schick, 1970

zoosophus Dyar and Knab, 1917

Important References:

Sourcouf & Gonzalez Rincones 1912 (as Promacleaya: emend.) [24]

Schick 1970 (keys, Terrens Group) [25]

Schick 1970 (keys, Terrens Group) [26]

Zavortink 1972 (tax.: resurrected from syn. with Finlaya) [27]

Reinert 2000 (to subg. of genus Ochlerotatus) [11]

Reinert et al. 2009 (as 'Ochlerotatus' ('Protomacleaya') sensu auctorum) [4]

Wilkerson et al. 2015 (to syn. of subg. Ochlerotatus of genus Aedes) [12]

Herein: to subg. of genus Aedes

Subgenus Rusticoidus Shevchenko and Prudkina 1973 (as subg. of genus Aedes; M*, key) [28].

Type species: Aedes refiki Medschid

albescens Edwards, 1921

bicristatus Thurman and Winkler, 1950

krymmontanus Alekseev, 1989

lepidonotus Edwards, 1920

provocans (Walker, 1848)

quasirusticus Torres Canamares, 1951

refiki Medschid, 1928

rusticus (Rossi, 1790)

ssp. subtrichurus Martini, 1927

subdiversus Martini, 1926

Important References:

Reinert 1999 (tax., review) [29]

Reinert 2000 (to subg. of genus Ochlerotatus) [11]

Reinert 2002 (F gen.*) [23]

Reinert et al. 2008 (phyl., class.) [3]

Reinert et al. 2009 (phyl., class.) [4]

Wilkerson et al. 2015 (to syn. of subg. Ochlerotatus of genus Aedes) [12]

Herein: to subg. of genus Aedes

Important taxonomic information and key references for the three Aedes subgenera treated herein (www.mosquitocatalog.org, 13 Sept. 2015); associated species are listed by subgenera. [Tax. = taxonomy, phyl. = phylogenetics, class. = classification, bion. = bionomics, distr. = distribution, subg. = subgenus, syn. = snynomy, * = all or part of life stage is illustrated, F = female, M = male, gen. = genitalia, emend. = emendation]

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