FNZ 42 - Aphodiinae (Insecta: Coleoptera: Scarabaeidae) - Introduction and systematics
Stebnicka, ZT 2001. Aphodiinae (Insecta: Coleoptera: Scarabaeidae). Fauna of New Zealand 42, 64 pages.
( ISSN 0111-5383 (print), ; no. 42. ISBN 0-478-09341-1 (print), ). Published 15 Jun 2001
The Aphodiinae is a large and diverse group of species inhabiting all zoogeographical regions. The fauna of aphodiines is generally well known for most of the world with the exception of Central and South America. These areas are the object of current studies of the author. The faunas of Australia, New Guinea, and neighbouring archipelagos have been recently treated in a series of papers by Stebnicka & Howden (1994, 1995, 1996, 1997) and Stebnicka (1998b). Before the present contribution was undertaken, very little was known of the faunistic composition of Aphodiinae in New Zealand. Early treatments of New Zealand aphodiines from 1846 to 1910 consist of isolated species descriptions by Broun (6 species), Sharp (4 species), White (1 species), and Lea (1 species). The first native New Zealand species to be discovered was Saprosites exsculptus (as Oxyomus exsculptus) which was collected at "Port Nicholson" (Wellington) and described by White (1846). Other than the listing of the species in a catalogue (Schmidt 1910) and their misleading diagnoses in a monograph by Schmidt (1922), the only subsequent papers dealing with the taxonomy of New Zealand species were the review of the genus Saprosites by Richards (1959) and some synonymical notes by Watt (1984). The status of nearly all species of Saprosites has been particularly enigmatic, since their types were not readily accessible to researchers as they were in European collections (mostly in BMNH), and specialists on Aphodiinae never saw them.
The present survey is based mostly on a large holding of material in the New Zealand Arthropod Collection, Auckland, and on the collections of various institutions mentioned in the section on Conventions. Approximately 1800 specimens and the type-series of all New Zealand species were examined. Twenty species are now known from New Zealand, nine of which are indigenous. Eleven are definite introductions from other countries; six from Australia -- Acrossidius tasmaniae (Hope), Tesarius sulcipennis (Lea), Proctophanes sculptus ((Hope), P. minor ((Blackburn), Ataenius brouni (Sharp), Saprosites mendax (Blackburn); two from the Americas -- Parataenius simulator (Harold) and Ataenius picinus Harold; one from Africa -- Australaphodius frenchi (Blackburn); and two cosmopolitan species of ultimate European origin -- Aphodius lividus (Olivier) and A. granarius (Linnaeus). Two species from the remaining nine are here described as new, and the genera Tesarius and Parataenius are recognised from New Zealand for the first time. In general, the New Zealand fauna of aphodiines is similar to that of Australia but strongly impoverished in the number of genera and species. The biogeographic affinities of the New Zealand Aphodiinae clearly indicate an ancient, Gondwanan origin in common with the Australian fauna.
The higher classification of the subfamily Aphodiinae (Lawrence & Newton 1995) has varied considerably over the last 80 years, and is still not completely settled. The basic systematic arrangement for the world species proposed by Schmidt (1922), based on 1137 species known at that time, is that on which new additions have been based. The latest world catalogue (Dellacasa 1988, 1989, 1991, 1996) lists about 3100 species, but additional taxa have been described since. The tribe Aphodiini forms the core of the subfamily, and is based on the huge genus Aphodius Illiger, with over 30 associated genera. The genus Aphodius is actually split into about 135 subgenera, with a number of additional species that cannot be properly assigned. Consequently, the existing keys for temperate Aphodius have become unworkable, and identification of species very difficult. My belief is that the use of species groups permits organisation within large genera (i.e., Ataenius: Stebnicka & Howden 1997) without the attendant nomenclatural problems associated with subgeneric names. It is obvious in these circumstances that a compromise must often be made between the practical aims of classification, its phylogenetic basis, and a system of naming.
The higher categories, such as tribes, genera, and species groups are poorly understood and nearly every author has a different arrangement. Part of the problem is due to the tremendous numbers of species, some of which fill the gaps between any arrangement of higher categories so far devised. Examples of confusion in relationships and classification are numerous, resulting from different levels of knowledge of the various species groups by authors studying only limited faunal areas. Recently a trend may be observed of a category inflation. The breaking up of polyphyletic groups does not necessarily led to a more practical system, if we do not know where the fragments belong. Various tribes of Aphodiinae have at one time or another been treated as subfamilies, however, they are not separated by a decided gap (if any), and none of the taxa covered here can seriously be elevated to subfamily rank. As in other groups of Scarabaeoidea, there has been considerable parallel evolution within the subfamily, and almost all characters claimed to be diagnostic at tribal or generic level have evolved independetly several times. In some cases, groups which are easily separated in the Old World, e.g., Psammodiini-Eupariini-Aphodiini, become almost indistinguishable in South America or Australia. Often seemingly distinct genera in temperate regions break down in the tropics and potentially strong defining characters are diluted and must be qualified. The following characterisation of Aphodiinae on a world basis and diagnostic characters for tribes found in New Zealand clearly indicate that all taxa above species level have to be defined by a mosaic of characters, a "polythetic classification" -- no character in isolation being diagnostic for all members.