Systematic Entomology (2005), 31, 113–144 DOI: 10.1111/j.1365-3113.2005.00307.x The phylogeny of Sericini and their position within the Scarabaeidae based on morphological characters (Coleoptera: Scarabaeidae) DIRK AHRENS Deutsches Entomologisches Institut im Zentrum fu¨r Agrarlandschafts- und Landnutzungsforschung Mu¨ncheberg, Germany Abstract. To reconstruct the phylogeny of the Sericini and their systematic position among the scarabaeid beetles, cladistic analyses were performed using 107 morphological characters from the adults and larvae of forty-nine extant scarabaeid genera. Taxa represent most ‘traditional’ subfamilies of coprophagous and phytophagous Scarabaeidae, with emphasis on the Sericini and other melo- lonthine lineages. Several poorly studied exoskeletal features have been examined, including the elytral base, posterior wing venation, mouth parts, endosternites, coxal articulation, and genitalia. The results of the analysis strongly support the monophyly of the ‘orphnine group’ þ ‘melolonthine group’ including phytopha- gous scarabs such as Dynastinae, Hopliinae, Melolonthinae, Rutelinae, and Cetoniinae. This clade was identified as the sister group to the ‘dung beetle line’ represented by Aphodius þ Copris. The ‘melolonthine group’ is comprised in the strict consensus tree by two major clades and two minor lineages, with the included taxa of Euchirinae, Rutelinae, and Dynastinae nested together in one of the major clades (‘melolonthine group I’). Melolonthini, Cetoniinae, and Rutelinae are strongly supported, whereas Melolonthinae and Pachydemini appear to be paraphyletic. Sericini þ Ablaberini were identified to be sister taxa nested within the second major melolonthine clade (‘melolonthine group II’). As this clade is distributed primarily in the southern continents, one could assume that Sericini þ Ablaberini are derived from a southern lineage. Plausibly, ances- tors of Sericini þ Ablaberini and Athlia were separated by a vicariance event, such as the separation of the African plate from the rest of Gondwana, whereas Sericini and Ablaberini probably diversified during the early Tertiary, with dis- persal of some basal Sericini to South America. Introduction represent a striking exception, being poorly known in terms of phylogeny, taxonomy, and larval morphology. The family Scarabaeidae (Scholtz, 1990) is one of the more The tribe Sericini occurs in the Holarctic (apart from the intensively studied groups of beetles with respect to their polar and subpolar region), Palaeotropic and Neotropic biology, taxonomy, and phylogeny. However, Sericine cha- region, being most diverse in tropical and subtropical fers, with 4000 described species in about 200 genera, zones (Fig. 1). It is absent entirely in New Guinea, Australia, New Zealand, and southern South America. As with other groups of phytophagous Scarabaeidae, adult Sericini are generalist herbivores. Maladera castanea Correspondence: Dirk Ahrens, Deutsches Entomologisches Institut (Arrow, 1913) feeds on more than 100 different plant spe- im Zentrum fu¨r Agrarlandschafts- und Landnutzungsforschung cies, preferring some thirty host plants with succulent roots Mu¨ncheberg, Eberswalder Str. 84, D-15374 Mu¨ncheberg, Germany. (Tashiro, 1987). The larvae, known as white grubs, feed on E-mail: [email protected] roots and underground stems of living plants (Ritcher, # 2006 The Royal Entomological Society 113 114 Dirk Ahrens –150° –120° –90° –60° –30° 0° 30° 60° 90° 120° 150° 60° 60° 30° 30° 0° 0° –30° –30° –60° –60° –150° –120° –90° –60° –30° 0° 30° 60° 90° 120° 150° Fig. 1. World-wide distribution of the Sericini (bold line). The Ablaberini (the presumed sister taxon according to Machatschke, 1959 – grey shaded) are limited to the Afrotropical region. 1966). Many species have been reported as crop pests. The ‘pseudoclypeus’; (c) anterior coxae conically produced; life cycle may take 1 or 2 years, depending on the climatic and (d) posterior coxae widened. He also assigned the conditions (Horion, 1958; Tashiro, 1987). The average known genera of Sericini to three subtribes: Phyllotocina, longevity of adults is about 1 month (Tashiro, 1987). In Sericina, and Trochalina. Although Machatschke (1959) the northern hemisphere, sericines overwinter in the larval based the monophyly of Sericinae on characters that stage, mainly as the third instar, by migrating into deeper might be considered as ‘good’ apomorphies, the characters soil layers. Many species of sericine chafers are nocturnal, used to argue for the monophyly of Melolonthinae have to and have an inconspicuous dark or brown colour. Sericines be considered in great part unambiguously plesiomorphic, often hide underground during the day (Tashiro, 1987). At such as the separated labrum and clypeus and the transver- dusk, the beetles come to the surface and feed on nearby sal carina of the anterior coxae. The arguments for the plants. Low temperatures may reduce flight activities sig- monophyly of Sericinae þ Melolonthinae are unconvincing nificantly (Ahrens, unpublished). because of confusion between apomorphies and plesiomor- Several hypotheses have been presented for the systema- phies in his argumentation scheme (e.g. position of stigmata tic position of the Sericini, but traditional placement has within abdominal sternites). been with other groups of phytophagous Scarabaeidae in Browne & Scholtz (1998) presented a phylogenetic ana- the subfamily Melolonthinae (Dalla Torre, 1912; Browne & lysis based on the comparative morphology of articulation Scholtz, 1998). The phylogeny of phytophagous and base of the hind wing of Scarabaeidae. They examined Scarabaeidae has been studied and discussed recently by numerous genera of sixteen high-ranked scarabaeid taxa several authors, but most provide no formal cladistic ana- traditionally classified as subfamilies, as well as taxa of lysis (Machatschke, 1959; Iablokov-Khnzorian, 1977; uncertain phylogenetic status. According to their phyloge- Nikolaev, 1998) and those who do consider the Sericini netic hypothesis, the Scarabaeidae comprised two major only superficially (Howden, 1982; Zunino & Monteresino, lineages: the ‘aphodiine line’ (containing Aphodiinae, 1990; Scholtz & Chown, 1995; Browne & Scholtz, 1996, including Aegialiini, Aulonocnemis, and Scarabaeinae), 1998, 1999; Jameson, 1998; Sanmartı´n & Martı´n-Piera, and the ‘orphnine line’ (containing Orphninae and all 2003). Machatschke (1959) hypothesized the monophyly major subfamily taxa of phytophagous scarabs). of the subfamily Sericinae containing the tribes However, their melolonthine lineage comprising the Diphucephalini, ‘Camentini’ (¼ Ablaberini), and Sericini ‘Melolonthinae’, Acoma, Chaunanthus, Oncerus, and the using the following characters: (a) the labrum and clypeus Hopliini was based on few apomorphies only, in contrast on one plane, fused, producing a labroclypeus; (b) the to most other clades. Moreover, they realized that the labrum establishes the anterior margin of this wing base offered few suitable characters to investigate # 2006 The Royal Entomological Society, Systematic Entomology, 31, 113–144 Phylogeny of Sericini 115 the Melolonthinae phylogeny in more detail due to a lack ‘melolonthine subgroup’ plus Orphninae based on the tree of significant differences. of Browne & Scholtz (1998: fig. 2). In contrast to coprophagous Scarabaeidae and ‘older’ lineages of Scarabaeoidea (Scholtz et al., 1994; Scholtz & Phylogenetic analysis Chown, 1995; Scholtz & Browne, 1996; Browne & Scholtz, 1999; Pretorius et al., 2000), the phylogeny of phytopha- The 107 morphological characters had a total of 261 gous Scarabaeidae is far from being resolved (Sanmartı´n& states. Inapplicable characters were coded as ‘–’, whereas Martı´n-Piera, 2003). This is strikingly evident when trying unknown character states were coded as ‘?’ (Strong & to place known fossils into the present phylogenetic system Lipscomb, 1999). All characters were run equally weighted (Krell, 2000). and nonadditive. The parsimony analysis was performed in Here, a cladistic analysis of morphological characters NONA 2.0 (Goloboff, 1999) using the parsimony ratchet was performed to determine the phylogenetic position (Nixon, 1999) implemented in NONA and run in WINCLADA of Sericini and their phylogenetic relationships to other version 1.00.08 as a shell program (Nixon, 2002). Two hun- phytophagous lineages of Scarabaeidae. The selected dred iterations were performed (one tree hold per iteration). taxa represent most widely recognized subfamilies The number of characters to be sampled for reweighting of coprophagous and phytophagous Scarabaeidae during the parsimony ratchet was determined to be ten. All (Nikolaev, 1998), with emphasis on the Sericini and searches were run under the collapsing option ‘ambiguous’, melolonthine lineages. which collapses every node whose minimum length is 0. State transformations were considered to be apomorphies of a given node only if they were unambiguous (i.e. without Materials and methods arbitrary selection of accelerated or delayed optimization) and if they were shared by all dichotomized most-parsimo- Taxon sampling nious trees. Bremer support (Bremer, 1988, 1994) and parsi- mony jackknife (Farris et al., 1996) were calculated using This study included forty-nine taxa representing twelve NONA to evaluate the trees. The search was set to a Bremer subfamilies, twenty-four tribes, and forty-eight genera of support level of 12, with seven runs (each holding a number Scarabaeidae. Character and character state