Acontiinae, Guenee, 1841

Keegan, Kevin L., Rota, Jadranka, Zahiri, Reza, Zilli, Alberto, Wahlberg, Niklas, Schmidt, B. Christian, Lafontaine, J. Donald, Goldstein, Paul Z. & Wagner, David L., 2021, Toward a Stable Global Noctuidae (Lepidoptera) Taxonomy, Insect Systematics and Diversity (AIFB) 5 (3), pp. 1-24 : 13-14

Acontiinae

We were particularly interested in Acontiinae after Keegan et al. (2019) discovered a clade of four genera, whose species are all Nearctic desert dwellers, that grouped sister to the Acontiinae . They transferred these genera, which had all been incertae sedis genera in Stiriinae, into Acontiinae and described the tribe Chamaecleini for the group. Here, we find seven additional generic-level taxa well supported as chamaecleines: ‘ Acontia’ viridifera (Hampson, 1910); Aleptinoides Barnes & McDunnough, 1912 ; Austrazenia Warren, 1913 ; ‘Azenia’ virida Barnes & McDunnough, 1916; Chalcoecia Hampson, 1908 ; Megalodes Guenée, 1852 ; and Trogotorna Hampson, 1910 (BS = 89, SH = 99.8, UF = 97; Fig. 3 ).

‘ Azenia ’ virida is unlike any other species of Azenia , which were well supported in Metoponiinae (BS = 96, SH = 100, UF = 100; Figs. 4 and 9A ), with multiple characteristics distinguishing it from other Azenia and uniting it with Chamaecleini . Azenia species feed on Cuscuta L. spp. ( Convolvulaceae ) (BugGuide 2020a, Fig. 9A , Supp. Document S2 [online only]), whereas ‘ Azenia ’ virida feeds on flowers and developing fruits of Malvaceae , specifically Sphaeralcea ambigua A. Gray (Supp. Document S2 [online only], Fig. 9B ), like all known Chamaecleini larvae. ‘ Azenia ’ virida larvae are also morphologically anomalous for Azenia but consistent with the known larvae of Chamaecleini genera in that they are foreshortened, with prolegs on A3–A4 ( Fig. 9B–D ) and an elongate spinneret. A new genus should be described for ‘ Azenia ’ virida. Megalodes eximia (Freyer, 1845) , the type species of Megalodes which is currently recognized in Metoponiinae , is also a Malvaceae specialist, feeding on flowers and developing fruits of Althaea L. and Malva L. ( Lederer 1870, Kravchenko et al. 2007). Hostplants for the remaining genera that we assigned to Chamaecleini are unknown, but we expect most if not all of them to be specialists on the flowers and/or developing fruits of Malvaceae . We found photos of an adult Chalcoecia emessa (Druce, 1889) , the type species of the genus which we included in our analysis, from Mexico settled on the leaves of Guazuma ulmifolia Lam. (Malvaceae) (iNaturalist 2020), whose geographic distribution agrees with that of C. emessa . Photographs of ‘A’. virida adults resting on Sphaeralcea ambigua leaves (BugGuide 2020b) led us to the discovery of its previously unknown life history and helped confirm its placement in Chamaecleini on the basis of its hostplant and larval morphology.

Before this study, the Chamaecleini consisted strictly of Nearctic desert taxa. These newly recognized members show the tribe to be represented in the Palearctic ( Megalodes eximia in southwestern Europe) as well as Gondwanan landmasses across the world (e.g., Chalcoecia in northern South America and Austrazenia in Australia). The Australian Noctuidae incertae sedis genus Calophasidia Hampson, 1908 may also prove to harbor chamaecleines as species within it group with known Chamaecleini species using BOLD’s Species Level Barcode Records database. Interestingly, the type species of Calophasidia was originally described in the genus Megalodes .

Our findings also highlight the revisionary work needed in the genus Acontia Ochsenheimer, 1816 . In our sampling of three species, we find evidence for at least three distinct genera represented in our analysis by A. lucida (Hufnagel, 1766) ; ‘A’. trabealis (Scopoli, 1763); and ‘A’. viridifera— with their crown node at a depth similar to those of the subfamily taxa in our analysis. Keeping ‘ Acontia ’ viridifera in Acontia would likely require the synonymization of a diverse group of as many as 17 genera in order to render the genus Acontia monophyletic. Worldwide, the genus contains 146 species ( Poole 1989), is exceptionally diverse morphologically ( Lafontaine and Poole 2010), and occurs on all continents except for Antarctica, with its type species, Acontia lucida , in Eurasia. Poole (1989) listed seven junior synonyms of Acontia , and there remains disagreement between Old World and New World systematists about the taxonomic limits of the genus ( Hacker et al. 2008, Lafontaine and Poole 2010).

‘Acontia’ trabealis (also Eurasian) is the type species of Emmelia , via its junior synonym Phalaena sulphuralis Linnaeus, 1767 , a junior subjective synonym of Acontia , and is well supported in a clade with three other Acontiinae genera: Ponometia Herrich-Schäffer, 1868 ; Spragueia Grote, 1875 ; and Tarache Hübner, 1823 (BS = 96, SH = 96.1, UF = 96). The latter three genera were considered distinct and valid in Lafontaine and Poole’s (2010) reclassification of the Nearctic acontiine fauna based on adult characters. Larvae and life history data also support their treatment as distinct genera, e.g., Nearctic Acontia are pudgy seed predators, with small heads for boring into fruits, whereas Ponometia , Spragueia , and Tarache are elongate, external, leaf feeders. So far as known, Ponometia are exclusively Asteraceae and Malvaceae feeders; Acontia and Tarache are Malvaceae feeders; and Spragueia feed on Asteraceae , Convolvulaceae , and Malvaceae —the second of these families being shared with Emmelia . We remove Emmelia from synonymy with Acontia and reestablish it as a full genus, stat. rev. See Hacker et al. (2008, 2010) for a list of species they considered to be in subg. Emmelia .

The Neotropical ‘ Acontia’ viridifera was originally described in the genus Hoplotarache Hampson, 1910 , which was based on the southern African type species Tarache mionides Hampson, 1905 . Hacker et al. (2008) synonymized Hoplotarache with Acontia on the basis of its type species, but did not treat any New World species of Hoplotarache . Based on similar arguments to those given above for Emmelia , ‘ Acontia’ viridifera should be removed from Acontia and placed in a separate genus, but we defer reassignment of the species until the New World and Old World species of Hoplotarache can be studied. In sum, there are good reasons to divide Acontia , but we caution that concepts and limits of the genera mentioned here are greatly in need of a global reassessment. For example, larval characters suggest that New World and Old World concepts of Acontia represent two distinct lineages, and that New World Tarache may be closer to Old World Acontia than either group is to New World Acontia . See Fig. 9E–H for a comparison of Old World and New World Acontiini larvae and Supp. Document S2 (online only) for more discussion on the relationships among genera of Acontiini .

Three predominantly Palearctic genera, Acrobyla Rebel, 1903 ; Apaustis Hübner, 1823 ; and Metopoceras Guenée, 1850 grouped in Acontiinae in a well-supported clade (BS = 99, SH = 99.5, UF = 100) apart from tribes Acontiini and Chamaecleini . Fibiger et al. (2009) listed Apaustis in Metoponiinae where it is currently recognized, but noted that the body structure and genitalia of both sexes in Apaustis suggested an affinity to Metopoceras . Both Acrobyla and Metopoceras were already in Acontiinae at the time of Fibiger et al. (2009), as they are currently. Our findings suggest Acrobyla and Metopoceras are appropriately considered as distinct genera; Acrobyla had previously been treated as a subgenus of Metopoceras ( Ronkay and Ronkay 1995) . These two genera were transferred from Oncocnemidinae to the acontiine tribe Armadini by Fibiger et al. (2010), and then into the acontiine tribe Hypercalymniini by Fibiger et al. (2011). However, their transfer to Hypercalymniini was precluded by Hacker’s (2010) prior synonymization of Hypercalymniini with Acontiini . Our results do not support Acrobyla , Apaustis , nor Metopoceras as belonging in Acontiini (or Chamaecleini ). It is possible that they belong in Armadini —the only other currently recognized acontiine tribe—but as we were unable to include Armada Staudinger, 1884 (the type genus of Armadini ) in our analysis we refrain from making a tribal assignment for these three genera. Metopoceras omar (Oberthür, 1887) larvae are known to feed on Plantago albicans L. ( Plantaginaceae ) ( Dumont 1927) and Apaustis larvae feed on Thymus L. ( Lamiaceae ) ( Beck 1999 –2000)—neither of these plant families is known to support any Acontiini or Chamaecleini .

Figures

Fig. 3. Maximum-likelihood tree inferred by RAxML analysis. Clade labels reflect our hypotheses about the extent of the various clades, and the taxonomic changes suggested in Results and Discussion. Lineages shown as being members of various clades may not have as yet been transferred into them. Bootstrap values ≥ 70 are shown at nodes.The scale bar shows estimated number of substitutions per site.The tree continues into Figs. 4–6. Clades are shown in three alternating colors to aid visibility.

Fig. 4. Continuation of maximum-likelihood tree inferred by RAxML analysis.

Fig. 9. Larvae of Azenia (Metoponiinae) (A) and Acontiinae (B–H). All last instars. (A) Azenia implora Grote, 1883. (B) ‘Azenia’ virida (Barnes & McDunnough, 1916). (C) Chamaeclea pernana (Grote, 1881). (D) Heminocloa mirabilis (Neumögen, 1884). (E) Acontia lucida (Hufnagel, 1767). (F) ‘Acontia’ cretata (Grote & Robinson, 1870); two individuals. (G) Tarache axendra Schaus, 1898. (H) Spragueia leo (Guenée, 1852). A, C, D, E, and H represent the type species for their respective genera;A–D, F, and G represent new life histories. See Supp Document S2 (online only) for localities, hostplant data, and a brief discussion of larval characters that have taxonomic implications. Acontia lucida image courtesy of Paolo Mazzei.