The Source of Chilopod Sensory Information: External Structure and Distribution of Antennal Sensilla in Scutigera coleoptrata (Chilopoda, Scutigeromorpha) Andy Sombke, 1,2 * Jo ¨ rg Rosenberg, 3 Gero Hilken, 3 Martin Westermann, 4 and Alfred Ernst 5 1 Zoological Institute and Museum, Cytology and Evolutionary Biology, Ernst-Moritz-Arndt-University of Greifswald, 17497 Greifswald, Germany 2 Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, 07745 Jena, Germany 3 Central Animal Laboratory, University Duisburg-Essen, Medical School, 45122 Essen, Germany 4 Electron Microscopy Center of the University Hospital, Friedrich-Schiller-University of Jena, 07743 Jena, Germany 5 Institute of Systematic Zoology and Evolutionary Biology with Phylogenetic Museum, Friedrich-Schiller-University of Jena, 07743 Jena, Germany ABSTRACT The investigation of the antennae of Scutigera coleoptrata (Linnaeus, 1758) by scanning electron microscopy (SEM) revealed the presence of five types of sensilla: sensilla trichodea, beak-like sensilla, cone-shaped sensilla brachyconica on the terminal article, sensory cones at the antennal nodes, and the shaft organ. Alongside the presence and absence of antennal sensillar types, three unique characters were found in the Scutiger- omorpha: the presence of long antennae with nodes bearing sensory cones, the presence of a bipartite shaft including the shaft organ, and the presence of beak-like sensilla. Neuroanatomical data showed that the animals’ brains are equipped with well-developed primary olfactory and mechanosensory centers, suggesting that the antennae must be equipped with specialized sensilla to perceive chemosensory and mechanosensory cues. With the evidence provided in this article for the Scutigeromorpha, SEM data are available at last on the antennal sensilla for all five chilopod taxa, allowing a com- parative discussion of antennal morphology in Chilopoda. J. Morphol. 000:000–000, 2011. Ó 2011 Wiley-Liss, Inc. KEY WORDS: scanning electron microscopy; antennal sensilla; Chilopoda INTRODUCTION Early investigation on the antennae and sensilla of Chilopoda was conducted during the 19th and early 20th century using light microscopy. The antennal sensilla were classified as touch bristles and pale cones (Leydig, 1860; Sazepin, 1884; Verhoeff, 1902–1925; Fuhrmann, 1922). Using electron microscopic methods, various chilopods were investigated with regard to their sensillar equipment, e.g., Lithobius forficatus, Lithobiomor- pha (Keil, 1975, 1976), Geophilus flavus, Geophilo- morpha (Ernst, 1976, 1979, 1981, 1983, 1996, 1997, 1999, 2000), Craterostigmus tasmanianus, Craterostigmomorpha (Ernst et al., 2006), and Cryptops hortensis, Scolopendromorpha (Ernst et al., 2009). However, the antennal sensilla of a representative of the Scutigeromorpha were never investigated in detail with these methods. Scutigera coleoptrata (Linnaeus, 1758) is a cre- puscular to nocturnal, ground-living centipede with long walking legs and body-long antennae. The rep- resentatives of the Scutigeromorpha are predators and feed on various living arthropods using their poisonous forcipules to kill their prey. The Scutiger- omorpha display many unique characters, such as the dorsal respiratory openings (Hilken, 1998) and compound eyes (Mu ¨ller et al., 2003, 2011). The eyes are characterized by high UV sensitivity, which may serve as an alarm signal to avoid bright light environments or to detect exits from concealed hid- ing places in soil crevices (Meyer-Rochow et al., 2006). However, behavioral experiments suggest that for hunting, visual cues are much less impor- tant than an olfactory guided search (Klingel, 1960; Sombke et al., 2011). Considering that many Chilo- poda including S. coleoptrata are active mostly dur- ing night time (Rosenberg, 2009), it seems reasona- ble to argue that mechanoreception and chemore- ception are the major sensory modalities involved in hunting for prey. Recent neuroanatomical studies show that the animals’ brains are equipped with well-developed primary olfactory and mechanosen- sory centers (Sombke et al., 2009, 2011), suggesting Contract grant sponsor: Max Planck Society. This study was sup- ported by DFG project HA 2540/8-1. *Correspondence to: Andy Sombke, Zoological Institute and Museum, Cytology and Evolutionary Biology, Ernst-Moritz-Arndt- University of Greifswald, 17497 Greifswald, Germany. E-mail: andy.sombke@uni-greifswald.de Received 17 February 2011; Revised 5 May 2011; Accepted 1 June 2011 Published online in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/jmor.10999 JOURNAL OF MORPHOLOGY 000:000–000 (2011) Ó 2011 WILEY-LISS, INC.