Macrodactylini

Katovich, Kerry, 2008, A generic-level phylogenetic review of the Macrodactylini (Coleoptera: Scarabaeidae: Melolonthinae), Insecta Mundi 2008 (23), pp. 1-78 : 2-4

History of Macrodactylini

The classification history of the tribe began with Latreille in 1825, who discussed the North American “ Macrodactyle” ( Macrodactylus ) as being “different” from the European Melolontha , into which it was originally placed by Fabricius (1775). Latreille did not provide a complete description of Macrodactylus or designate any species in this work. Le Peletier and Serville later provided a complete description of the genus in 1828. The genus is credited to Dejean (1821) who designated the species Melolontha subspinosus Fabricius and Melolontha angustus Fabricius as members of Macrodactylus , but did not discuss them in a relational sense. Kirby (1837) placed M. subspinosus (Fabricius) into a newly erected family, Macrodactylidae. It is unclear why Kirby did this; presumably he reasoned that this unique North American species differed substantially from other European species of Melolontha , the genus into which it had historically been placed. Le Peletier and Serville (1828) described Ceraspis , Dasyus , Dicrania , and Plectris . This work provided substantial descriptions of the genera and included a thorough generic description of Macrodactylus . Harris (1827) established the genus Dichelonyx from North America for Melolontha linearis Gyllenhal (1817) and suggested it was related to the macrodactyline scarabs. Much confusion has surrounded this genus. Schönherr (1817) noted Melolontha elongata Fabricius (1792) was a primary junior homonym of Melolontha elongata Olivier (1789) , renaming the former Melolontha elongatula . In 1837, Harris recognized that M. elongatula Schönherr was the senior synonym of M. linearis Gyllenhal (1817) , the generic type species of Dichelonyx at this time. Therefore, the appropriate type species of the genus is Dichelonyx elongatula ( Schönherr 1817) . Kirby (1837) inappropriately emended the generic name to Dichelonycha , and named three new species. This spelling error was repeated until 1920 when Leng correctly brought back the original spelling. The 1820s ended with Mannerheim (1829) describing Isonychus .

The 1830s saw a series of monotypic genera described: Hadrocerus Guérin-Méneville (1831) , Clavipalpus Laporte (1832) , Rhinaspis Perty (1833) , Ancistrosoma Curtis (1835) , and Liogenys Guérin-Méneville (1838) .

The 1840s saw little work in the macrodactylines. Laporte (1840) described the monotypic Manopus, Curtis (1844) described the monotypic Pacuvia , and Erichson (1847) described the monotypic Diaphylla . In 1848, Erichson placed two European genera, Macrophylla Hope 1837 and Onochaeta Erichson 1848 , into his newly erected Macrodactylidae, under the broader group Melolonthidae . He expressed that several North and South American genera reside within this family ( Ancistrosoma , Ceraspis , Dasyus , Dichelonycha , Isonychus , Liogenys , Macrodactylus , Plectris , and Rhinaspis ). Subsequent workers have not placed Macrophylla and Onochaeta in the Macrodactylini .

The mid-1800s saw the most taxonomic work on the Macrodactylini . Solier (1851) described the monotypic Chremastodus . Between 1850 and 1851 Blanchard described numerous genera within the Melolonthinae . Blanchard placed five previously described genera and four newly described genera ( Barybas , Calodactylus , Dejeania , Schizochelus ) into his “Omalopliitae” and seven previously described genera and 14 newly described genera ( Alvarinus , Anomalochilus , Anoplosiagum , Blepharotoma , Chariodema , Chlaenobia , Demodema , Faula , Gama , Hilarianus , Homalochilus , Mallotarsus , Pachylotoma , Philochloenia ) in his “Melolonthitae.” Blanchard did not provide clear definitions for these groups.

Burmeister (1855) produced the first substantial work on the macrodactylines. Burmeister’s work was mainly a response to Blanchard’s work, but he did not acknowledge the Blanchard genera. He pro- vided the first diagnosis of the macrodactyline group as well as the first keys to a number of genera. Burmeister is credited with the first description of the present day tribe Macrodactylini , but he did not use this term. He designated this group as the Macrodactylidae, and included seven subgroups: Ceraspidae ( Ancistrosoma and Ceraspis ); Dichelonychidae ( Dasyus , Dichelonycha , and Dioplia Burmeister ); Dicraniadae ( Dicrania and Rhinaspis ); Isonychidae ( Amphicrania Burmeister , Corminus Burmeister , Diaphylla , Hadrocerus , Isonychus , Macrodactylus , Manopus and Philochloenia sensu Burmeister ); Liogenyidae ( Barybas sensu Burmeister , Ctenotis Burmeister , Harpodactyla Burmeister , and Liogenys ); Microcraniadae ( Ctilocephala Burmeister , Hercitis Burmeister , and Microcrania Burmeister ); and Plectridae ( Oedichira Burmeister and Plectris ). Within this work Burmeister attributed the name Macrodactylidae to Kirby (1837).

Lacordaire (1856) provided the most complete treatment of the macrodactylines yet produced. His Genera des Coléoptères provided extensive redescriptions of genera, including the Blanchard genera, to which Lacordaire had access at the Paris Museum. Although his treatment of genera was global, with keys and definitions of upper level divisions down to genera, he did not cover the Burmeister genera in his work. The Macrodactylides were designated along with a description of the subtribe. Within this subtribe, genera were placed into four groups: Ceraspides ( Ancistrosoma , Ceraspis , Chariodema , Dejeania , and Manopus ), Dicranides ( Dasyus and Dicrania ), Macrodactylides ( Calodactylus , Isonychus , Macrodactylus , and Schizochelus ), and Philochlenides ( Alvarinus , Anomalochilus , Anoplosiagum , Barybas (sensu Blanchard) , Blepharotoma , Chlaenobia , Demodema , Gama , Mallotarsus , Philochloenia (sensu Blanchard) , Plectris , Rhinaspis , and Ulomenes ). Genera previously within the historic Macrodactylini fell into two additional subtribes: Sericoides, in which he placed Diaphylla under his Heteronycides group and Dichelonycha into his Sericoides group; Clavipalpus , Liogenys , Hilarianus , Homalochilus , and Pachylotoma were placed in the Clavipalpides group. The significance of Lacordaire’s work is best thought of in two respects. The first is the global treatment of genera and tribes along with the inclusion of descriptions at all taxonomic levels. The second effect of this work is the redescriptions of Blanchard’s genera. Blanchard’s descriptions were exceedingly short and uninformative, but after Lacordaire’s work these genera could be more clearly understood. LeConte (1856), paralleling Lacordaire’s work, designated for the first time the Macrodactylini , containing Macrodactylus , and separated several genera into newly formed tribes, such as Dichelonychini , containing Dichelonyx . The 1850s ended with Thomson (1858) describing the monotypic Diphydactylus .

The 1860s saw only one new genus described in the Macrodactylini . Philippi (1861), described the monotypic Acanthosternum . The first substantial catalogue of Scarabaeidae was produced during this time period by Harold (1869a). He treated many of the historic genera as belonging to the Melolonthini . Not all genera historically associated with Macrodactylini were included within this work, and no clear reasons were provided for this classification.

In the 1870s the North American worker Horn (1876) established Coenonycha and placed into it Dichelonyx rotundata (LeConte) , indicating the close relationship to Dichelonyx . In 1878, Fairmaire and Deyrolle described five species in two genera from Asia: Diphycerus and Hyperius . Fairmaire (1889) described the monotypic Issacaris , and the century ended with Linell (1896) describing the North American Gymnopyge .

Dalla Torre (1913) cataloged the Macrodactylini , and several historical macrodactyline genera were placed back into or removed from the tribe without justification. Numerous synonyms relevant to Macrodactylini were recorded: Dioplia synonymous with Calodactylus , Amphicrania (in part) and Pacuvia synonymous with Liogenys , Amphicrania (in part) synonymous with Clavipalpus , Microcrania synonymous with Barybas , Faula (in part) synonymous with Ceraspis , and Faula (in part) synonymous with Ancistrosoma . The justification for these synonyms and changes in tribal status were not provided, nor was a clear explanation given for the multiple synonyms of genera, such as Faula and Amphicrania . Several genera not placed previously into this tribe were included without justification as well, including Epicaulis Dejean and Oxychirus Quedenfeldt. Subsequent workers have considered Oxychirus a member of Phaenomerinae. Epicaulis has not been discussed, likely due to the lack of adequate descriptions and type material.

Arrow (1913) described the monotypic Pectinosoma . He later (1920) placed it into the “Macrodactylides” and provided a detailed discussion of the Asian genera Dichelomorpha Burmeister , Diphycerus Fairmaire , and Xenoceraspis (new genus and species) from India. The German worker Moser described nine South American genera (1918, 1919a, 1919b, 1921a, 1921b and 1924): Agaocnemis , Anomonyx , Aulanota , Chariodactylus , Gastrohoplus , Manodactylus , Manonychus , Pseudohercitis , and Rhinaspoides .

The North American worker Saylor (1938) described Canestera . In 1940, he corrected a homonym, replacing Mosers’s Anomolonyx (1921) with Anomonyx .

The 1940s saw little work on Macrodactylini , with two genera described during this time period: Saylor (1946) described Zabacana and Arrow (1948) described the monotypic Ceratolontha . Blackwelder (1944) produced a checklist of Coleoptera in Mexico, Central America, West Indies, and South America. Notable in the checklist was the removal of Chlaenobia from the macrodactylines and placement as a synonym of Phyllophaga Harris (Melolonthini) and the inclusion of Isoceraspis Ohaus (1911) as a genus. Isoceraspis has subsequently been treated as a subgenus of Ceraspis as it was originally designated. Several South American genera are absent from the list without explanation.

Janssens (1949) proposed a classification of Scarabaeidae , including a key to tribes (including Macrodactylini ). This key was based on what Janssens described as European members of these tribes, but Macrodactylini (non-European) were included. This work was one of the first to provide significant tribal level characters for Macrodactylini .

In the 1950s the Chilean worker Gutiérrez (1952) described the monotypic Eubarybas ; he also moved the Chilean Apterodema paraguayensis Arrow 1903 to the new genus Apterodemidea , and Liogenys tarsalis Moser 1921 to the new genus Homoliogenys . Gutiérrez provided a key to these genera and species along with several other Chilean melolonthine genera. The Argentinean worker Martínez (1957) described Astaenoplia and moved Schizochelus longipes Philippi to his new genus Astaenosiagum .

In the 1960s Frey began working on the Macrodactylini , describing the monotypic Metaceraspis (1962) . In 1967 he added the monotypic Hamatoplectris , and in 1971 the monotypic Pseudoisonychus . Frey described numerous species within existing “macrodactyline” genera. His works also included regional keys for Ceraspis ( Frey 1962) , Dicrania ( Frey 1972a) , Isonychus ( Frey 1964, 1965, 1970), Liogenys ( Frey 1969) , and Plectris ( Frey 1967) . Frey (1972b) removed Blepharotoma Blanchard from Macrodactylini , placing it in Sericoidini . Ritcher (1966) proposed the tribe Plectrini , composed of Plectris , based on larval characters. He demonstrated that the tribes Macrodactylini , Dichelonychini (sensu LeConte) , and Plectrini were separable based on larval characters. This was based on the few known larvae of Macrodactylus , Dichelonyx , Coenonycha , and Plectris . North and South American workers treating the tribes have apparently overlooked or discounted this work.

In 1975 Martinez transferred two genera from the Pachydemini and placed them into the Macrodactylini : Paulosawaya Martínez and D’Andretta 1956 , and Pseudoleuretra Martínez and D’Andretta 1956 . Since 1975 no new macrodactyline genera have been described. There have been numerous specieslevel contributions, mainly for Central American and Caribbean species. Notable works have included regional generic keys: Carrillo and Gibson (1960), Garcia-Vidal (1982), Arce-Pérez and Morón (2000).

Britton’s (1957, 1978) work on Australian Melolonthinae included a tribal description of Macrodactylini , due the presence of an invasive Plectris in Australia. Baraud (1992) included Macrodactylinae in his key to Palearctic subfamilies of Melolonthidae , but provided no comment on the subfamily, which is absent from Europe. The characters used in this tribal description are similar to those of Janssens (1946).

Evans (2003) published a catalogue of South American Melolonthinae ; this was supplemented in 2005 (Smith and Evans 2005), and an updated catalogue was published in 2005 (Evans and Smith 2005). Numerous changes were made to the Macrodactylini : Homalochilus Blanchard , Homoliogenys Gutiérrez , Liogenys Guérin-Méneville , and Pacuvia Curtis were moved to the re-erected Diplotaxini ; Apterodemidea Gutiérrez was placed in the Sericoidini ; and Acanthosternum Philippi 1861 was placed as a junior synonym of Modialis Fairmaire and Germain 1860 in Melolonthini .