The Peristomatic Structures of Lithobiomorpha (Myriapoda, Chilopoda): Comparative Morphology and Phylogenetic Significance Markus Koch 1 * and Gregory D. Edgecombe 2 1 Institut fu ¨r Biologie, Systematik und Evolution der Tiere, Freie Universita ¨ t Berlin, D-14195 Berlin, Germany 2 Department of Palaeontology, The Natural History Museum, London SW7 5BD, UK ABSTRACT A comparative survey of the epipharynx and hypopharynx of lithobiomorph centipedes by light and scanning electron microscopy examines 18 species that sample the major groups of both families, the Litho- biidae and Henicopidae. Cladistic analysis of 11 charac- ters of the peristomatic structures together with 29 addi- tional morphological characters serves as a basis for interpreting the evolution of the lithobiomorph peristo- matic structures. Scutigeromorpha is used for outgroup comparison in the framework of a homology scheme for the basic components of the epi- and hypopharynx. Com- pared to other chilopods, the monophyly of Lithobiomor- pha is supported by a row of distinctive bottle-shaped gland openings at the border between the labral and cly- peal parts of the epipharynx, as well as by a distinctive shape of the hypopharynx. Paired rows of elongate spines on the clypeal part of the epipharynx are an apo- morphic character of Lithobiidae. The transformation of these spine rows into a few groups of branching spines is characteristic for the Monotarsobius group sensu Ver- hoeff. Similar groups of branching clypeal spines charac- terize the Anopsobiinae within Henicopidae, whereas Henicopinae possess a dense cluster of short, simple spines instead. The recently described genus Dzhunga- ria is resolved closer to Henicopinae than to Anopsobii- nae, a hypothesis supported by a field of grooves on the medial labral part of the epipharynx. Monophyly of Henicopidae does not receive unique support from the peristomatic structures although two homoplastic char- acters contribute to this node; among these, the reduc- tion of a median spine field between clypeal and labral parts of the epipharynx to a narrow transverse band also supports a close relationship between the Ezembius group and Hessebius within Lithobiidae. An Ezembius 1 Hessebius clade is additionally supported by the absence of a transverse bulge between the clypeal and labral parts of the epipharynx, a character otherwise present in all lithobiomorph species studied so far. Lithobius is resolved as polyphyletic, with different species being most closely related to such genera as Australobius, Hessebius and Pleurolithobius. J. Morphol. 269:153–174, 2008. Ó 2007 Wiley-Liss, Inc. KEY WORDS: Chilopoda; Lithobiomorpha; epipharynx; hypopharynx; phylogeny The morphology of the preoral chamber has hardly figured in the systematics of Chilopoda, but recent work on the Scutigeromorpha has high- lighted the value of the epipharynx and hypophar- ynx for phylogenetics (Koch and Edgecombe, 2006). The most comprehensive early descriptions of the epipharynx and hypopharynx of chilopods were made by Verhoeff (1918 in Verhoeff, 1902– 1925), who referred to these circumoral structures (together with the pharynx) as ‘‘peristomatische Organe’’ (peristomatic organs). Verhoeff’s data on the Lithobiomorpha, however, were limited to observations on the lithobiids Lithobius forficatus, Eupolybothrus fasciatus, and E. tridentinus. Other accounts of the head morphology of Lithobiidae, including certain aspects of the peristomatic struc- tures, include descriptions of Lithobius forficatus by Sograff (1880), Fahlander (1938), and Rilling (1968), and a detailed treatment of Pseudolitho- bius megaloporus by Applegarth (1952). The peri- stomatic structures of the second family of Litho- biomorpha, the Henicopidae, have not been docu- mented, which has prohibited using characters of the epipharynx and hypophrarynx in lithobio- morph systematics or for addressing a controversy over the monophyly of Lithobiomorpha (Borucki, 1996; Prunescu, 1996). In this study, we examine the peristomatic struc- tures of 11 species of Lithobiidae and 7 species of Henicopidae by light and scanning electron micro- scopy. In the context of morphology in Scutigero- morpha (Koch and Edgecombe, 2006) and other pleurostigmophoran chilopods, variation in the lithobiomorph peristomatic structures is analyzed cladistically together with a dataset from other morphological systems. Our objectives are twofold; on the one hand to incorporate Lithobiomorpha Contract grant sponsor: NSF; Grant number: EAR 0313698. *Correspondence to: Dr. Markus Koch, Institut fu ¨ r Biologie, Sys- tematik und Evolution der Tiere, Freie Universita ¨t Berlin, Ko ¨nigin- Luise-Str. 1-3, D-14195 Berlin, Germany. E-mail: mkoch@zoosyst-berlin.de Published online 12 October 2007 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/jmor.10578 JOURNAL OF MORPHOLOGY 269:153–174 (2008) Ó 2007 WILEY-LISS, INC.