ARTICLE IN PRESS Organisms, Diversity & Evolution 4 (2004) 1–34 www.elsevier.de/ode Comparative study of thoracic structures of adults of Hydrophiloidea and Histeroidea with phylogenetic implications (Coleoptera, Polyphaga) Rolf G. Beutela,*, Albrecht Komarekb a Institut fur. Spezielle Zoologie und Evolutionsbiologie, Friedrich-Schiller-Universitat. Jena, Erbertstrasse 1, D-07743 Jena, Germany b Naturhistorisches Museum Wien, Burgring 7, A-1010 Wien, Austria Received 24 March 2003; accepted 30 October 2003 Abstract External and internal structures of adults of Hydrophiloidea and Histeroidea were examined. Skeletal and muscular features of Helophorus aquaticus and Margarinotus brunneus are described in detail. Morphological data are presented as a list of characters and data matrix, and analysed together with other characters of adults, characters of larvae, and characters related to reproduction, habitats and feeding habits. The results of the analysis (characters unweighted) of the full dataset unambiguously support the monophyly of the following clades: [Scarabaeoidea (represented by a genus of Lucanidae and a genus of Scarabaeidae)+Hydrophiloidea+Histeroidea], [Hydrophiloidea+Histeroidea], Histeroidea, [Sphaeritidae+Histeridae], Hydrophiloidea, Hydrophiloidea (excluding Helophoridae), Hydrophiloidea (excluding Helophoridae and Hydrochidae), [Epimetopidae+Georissidae], and [Spercheidae+Hydrophilidae]. The monophyly of all histeroid and hydrophiloid families and of Hydrophilidae (represented by hydrophilines and sphaeridiines) excluding Berosus is also supported. The placement of Scarabaeoidea is in contrast to a taxonomic treatment as a lineage with the same rank as Staphyliniformia. Hydraenidae are not closely related to Hydrophiloidea. The clade comprising Hydrophiloidea and Histeroidea is well supported, but mainly by larval features correlated with predacious habits. The position of Spercheidae implies that a considerable number of seemingly plesiomorphic features of the head are due to reversal and specialized feeding habits (filter feeding). Histeridae show a highly derived pattern of thoracic features with unusual muscular modifications, a long horizontal, dorsal part of the mesopleuron, widely separated metacoxae and a strongly simplified metafurca. Hydrophiloidea are well supported by character transformations of the thorax and other body parts, which are probably related to the invasion of the aquatic habitat in the adult stage, e.g. surface modifications related to the ventral plastron. Georissidae+Epimetopidae are characterized by derived features, which may be the result of a secondarily terrestrial or semiterrestrial life style (partly reduced ventral pubescence), and by a weakly sclerotized mesonotum, mesofurca and metafurca. Hydrochidae, Georissidae and Epimetopidae show a considerable number of autapomorphies, whereas Helophoridae are probably close to the groundplan of Hydrophiloidea. The adaptations to an aquatic life style and the specific habits are very different in Hyrophiloidea and the aquatic groups of Adephaga. r 2004 Elsevier GmbH. All rights reserved. Keywords: Staphyliniformia; Hydrophiloidea; Thoracic structures; Phylogeny; Evolution See also Electronic Supplement at http://www.senckenberg.de/odes/04-01.htm *Corresponding author. E-mail address: [email protected] (R.G. Beutel). 1439-6092/$ - see front matter r 2004 Elsevier GmbH. All rights reserved. doi:10.1016/j.ode.2003.10.001 ARTICLE IN PRESS 2 R.G. Beutel, A. Komarek / Organisms, Diversity & Evolution 4 (2004) 1–34 Introduction Histeridae, Sphaeritidae or Synteliidae morphological studies of the thorax and its musculature were so far Hydrophiloidea and Histeroidea are groups which missing. Therefore, the main goal of the present have attracted a lot of attention, and recently a contribution is to provide more detailed information considerable number of studies were dedicated to the on thoracic structures of hydrophiloid and histeroid morphology of larvae (Archangelsky 1997; Beutel 1999) beetles. One representative of the Histeroidea, Margar- or adults (Beutel 1994; Beutel et al. 2001; Anton inotus brunneus (Fabricius), and one representative and Beutel 2004), systematics (Hansen 1991, 1997a; of Hydrophiloidea, Helophorus grandis Illiger, are Beutel 1994; Archangelsky 1998; Caterino and Vogler described in detail, and characters potentially rele- 2002), or taxonomy (e.g. Hansen 1997a, 1999). Never- vant for phylogenetic analyis are presented in a theless, the level of knowledge on structural features data matrix. Thoracic muscle features are presented is not fully satisfying at present. Information on in Table 1. These are combined with further charac- structural features of the thorax is surprisingly sparse. ters of adults and larvae, and subjected to cladistic The thoracic musculature of two representatives of analysis. The phylogenetic results are discussed, and Hydrophilidae (sensu Hansen 1991) was examined by possible implications for the classifications are consid- Larsen! (1966), and the data were presented in a ered. The role of thoracic character transformations comprehensive table in this study. Thoracic features in the evolution of the groups is outlined, as are were treated in a list of characters and included in a different evolutionary trends in Hydrophiloidea and large data matrix by Hansen (1991, 1997a). However, he hydradephagan beetles. The data presented may con- did not present detailed descriptions and did not tribute to a future total evidence analysis, including examine internal structures. For members of the molecular data. Table 1. Thoracic muscles of Hydrophiloidea and Histeroidea BeutelandHaas12369 101112131415161718222324252730313940424344454647505152535455585960 Larsen12345! 6 7891011121314151617181920282930313233 35363637383940 Genus Priacma x xxxx xxxxxxxxxx xxx xxxxxxxxxxxxx—xxx—xx Hydroscapha x xxxx x—xx—xxx?x xxx xxxx—x——x————xx xx —x Ochthebius —?x —x x x —x ——x x x x x x ? ? —x?x x x x ———? x ——? ? —— —? Helophorus x xx?xxx—x——xxxxx xx—?—xxxxx——— —x ——— x x ——x Hydrophilus x x—xx x—x——xxxxx xx——xxxxx——x—x———x — ——x Sphaeridium x x—xx x—x——xxxxx x————xxxx——— —x ——— x — ——x Margarinotus x x—xx x—x——xxxxx?xx——xxxxx——x—x———?x1 x——x Nicrophorus x x —x x x —x ——x x x x x x x x —x x x x x ————x ——— x x — —x Creophilus x x —x x x —x ——x x x x x x x — ——x x x x ——x —x ——— x —— —x Lucanus x x —x x x —x x —x x x x — x x x ——x x x x ————x ——— x x — —x Amphimallon x x—xx x—xx—xxxx— x x x ——x —x x ——x —x ——— x —— —x Aphodius x x —x x x —x ——x x x x — x x x ——x x x x ——x —x ——x x x — —x Cetonia x x —x x x —x ——x x x x — x x x ——x x x x ——x —x ——— x —— —x Beutel and Haas 61 62 64 65 66 67 68 69 70 71 72 79 80 82 83 84 85 86 87 88 90 91 93 94 95 96 97 98 00 01 02 03 04 05 07 08 09 11 13 Larsen! 41 42 43 44 45 46 52 47 48 49 50 60 61 62 63 64 65 66 67 68 69 70 71 71 72 73 74 75 76 77 78 79 81 82 83 84 85 Genus Priacma x xxxx xxxxxxxxxx xxx xxxxxxxxxxxxxx xxxx xxx Hydroscapha x —xxxxxxx—xxx——xxx ——x—x—abxx—x—xxx?—x—x Ochthebius x ——?—xx—x——xxx?—?xxx——x—xx?abxx—xxx ?xxx xxx Helophorus x x—x—?xx—x——xxx—xxx ——x—xxabxx—x xx x xxx xx x Hydrophilus x x—x—xx—— —xxxx—xxx ——x—xxabxx—x xx — xxx x— x Sphaeridium xx— x—xx—x—xxxx—xxx ——x—xxabxx—x xx x xxx xx x Margarinotus x xxx—xx—?—xxxx—xx—?——x—xxab— xx— xx — xx—?x— x Nicrophorus x ——x—xx—x——xxx—xxx ——x—xxabxxxx xx x xxx x— x Creophilus x x—x—x——x——xxx—xxx ——x—xxabxxxxxx —xxx x—x Lucanus x x —x — x x ————x x x — x x x ——x —xxabxxxxxx xxxx x—x Amphimallon x x —x — x ———x —x x x — x x x ——x —xxabxxxxxx —xxx x—x Aphodius x x—x—xx———xxxx—xxx ——x—xxabxxxxxx xxxx x—x Cetonia x x —x — x ———x —x x x — x x x ——x —xxab—x—xxx —xxx x—x Muscle numbers refer to Beutel and Haas (2000: 1–31 prothorax, 39–72 mesothorax, 79–113 metathorax), and Larsen! (1966), respectively. Intrinsic leg muscles not listed (present in all adult beetles). x=present; —=absent; a, b=separate subcomponents of one muscle; boldface=characters which may provide phylogenetic information; 1=with atypical origin (see text). ARTICLE IN PRESS R.G. Beutel, A. Komarek / Organisms, Diversity & Evolution 4 (2004) 1–34 3 Materials and methods Morphological techniques List of taxa examined (classification after Hansen Thoracic segments of selected specimens (micr.) were embedded in Historesin, sectioned at 3–5 mm (cross- 1991) sections and longitudinal sections), and stained with methylene-blue and acid fuchsine. Specimens of S. Specimens from the collection of the first author bipustulatum and H. fuscipes were examined with a (collected in Thuringia unless otherwise noted) are SkyScan X-ray CT (Hornschemeyer. et al. 2002). marked with one asterisk, and specimens from the Drawings were made using an ocular grid or a camera Naturhistorisches Museum Wien with two asterisks. lucida. The muscular nomenclature introduced by Representatives of most species were collected at Beutel and Haas (2000) is used in the text, and the different localities. corresponding numbers are used in the illustrations. Staphylinoidea, Hydraenidae, Ochthebiinae: Ochthe- Scanning electronic microscopy was carried out with Ã/ÃÃ bius brevicollis (Baudi, 1864) (diss.=dissected), an FEI (Philips) XL 30 ESEM TMP. Ochthebius exsculptus Germar, 1824Ã/ÃÃ (FAE=etha- nol-formaldehyde-acetic acid; micr.=microtome sec- tions); Hydraeninae: Hydraena gracilis Germar, 1824Ã/ Cladistic analysis ÃÃ (diss.). Staphylinoidea, Leiodidae: Catops subfuscus Kellner, The analysis of the interrelationships of hydrophiloid 1846Ã/ÃÃ (diss.); Silphidae: Nicrophorus vespillo (Lin- (11 genera) and histeroid subgroups (four genera) is naeus, 1758)Ã/ÃÃ (diss.). based on 111 external and internal characters of the Scarabaeoidea, Lucanidae: Lucanus cervus Linnaeus, adult thorax, and 46 additional characters of larvae or 1758Ã/ÃÃ (diss.), Platycerus caraboides Linnaeus, 1758Ã adults and from bionomics.