Unusual Labial Glands in Snakes of the Genus Geophis Wagler, 1830 (Serpentes: Dipsadinae) Leonardo de Oliveira, 1,2 Ana L ucia da Costa Prudente, 3 and Hussam Zaher 1 * 1 Museu de Zoologia da Universidade de S~ ao Paulo, Avenida Nazar e 481, Ipiranga, S~ ao Paulo 04263-000, Brazil 2 Programa de P osGraduac¸ ~ ao em Zoologia, UNESP, Rio Claro, S~ ao Paulo, Brazil 3 Museu Paraense Em ılio Goeldi, Caixa Postal 399, Bel em, Par a, 66077-530, Brazil ABSTRACT Geophis belongs to the goo-eating dipsa- dine assemblage of snakes that are known to feed exclusively on earthworms, snails, and slugs. Although the unusual feeding strategies of the goo-eating dipsa- dines are well known (but poorly documented), little attention has been paid to their internal anatomy. Here, we describe a new and noteworthy morphological and histochemical condition of the infralabial glands in three species of Geophis (G. brachycephalus, G. nasalis and G. semidoliatus), all earthworm feeders. Their infralabial glands are constituted of two distinct parts: an anterolateral portion composed of mucous and sero- mucous cells that stretches from the tip of the dentary to the corner of the mouth, and a tubular posterome- dial portion that is exclusively seromucous. The antero- lateral portion receives fibers of the levator anguli oris muscle that attaches on its posterodorsal extremity while the posteromedial portion extends posteriorly to the corner of the mouth where it receives fibers of the adductor mandibulae externus medialis muscle. Fur- thermore, the posteromedial portion of the infralabial gland is constituted by large acini filled with secretion that is periodic acid-Schiff positive. These acini release their secretion directly into a large lumen located in the middle of the glandular portion. In the three spe- cies examined, the supralabial glands show a tradi- tional configuration, being constituted of mucous and seromucous cells and retaining an enlarged part in its caudal region that resembles a Duvernoy’s gland. The presence in Geophis of an expanded lumen in part of the infralabial gland that is compressed by an adjacent muscle suggests a more specialized role for the secre- tion produced by these glands that may not be related to envenomation but rather to prey transport and mucus control. J. Morphol. 275:87–99, 2014. V C 2013 Wiley Periodicals, Inc. KEY WORDS: dipsadidae; goo-eaters; adductor muscles; lumen; supralabial glands; infralabial glands INTRODUCTION In snakes, the labial (infralabial and supralabial glands), venom, and Duvernoy’s glands are among the best-known oral glands (Taub, 1966). Venom glands are present only in advanced snakes (Cae- nophidia) with a front-fanged venom delivery sys- tem (displayed by some Atractaspididae, all Elapidae and Viperidae), while Duvernoy’s glands are present in a number of endoglyptodont colubroidean snakes (sensu Zaher et al., 2009) without a front-fanged system (Vidal, 2002; Kar- dong, 2002). Infralabial and supralabial glands seem to occur in all snakes that have been studied to date (Smith and Bellairs, 1947; Kochva, 1978; Underwood, 2002). The usual classification of reptile oral glands is based on the types of secretion granules, and depends on the distinct histochemical composition of these granules (Gabe and Saint-Girons, 1969; Kochva, 1978). Although there is still uncertainty regarding the relationship between cell types rec- ognized by histologists and their secretion, it is clear that mucous cells secrete mucins and that all venom glands contain serous cells of some type (Underwood, 1997). Venom glands are generally surrounded by muscles that act as compressors during the bite (Haas, 1973), have a lumen (a large encapsulated reservoir where the secretion may be stored), and release venom through a single duct that connects directly with the fang, constituting a high- pressure system (Kardong and Lavin-Murcio, 1993; Jackson, 2003). The venom and Duvernoy’s glands are considered homologous and a compo- nent of the venom-delivery system in snakes, which are usually constituted of serous cells and associated with toxin production (Taub, 1966; Kochva, 1987; Jackson, 2003; Fry et al., 2008). Contract grant sponsor: Fundac¸~ ao de Amparo  a Pesquisa do Estado de S~ ao Paulo (FAPESP); Grant numbers: 2008/57102-1 (LO), 11/50206-9 (HZ); Contract grant sponsor: Conselho Nacional de Desenvolvimento Cient  ıfico e Tecnol ogico (CNPq); Grant num- bers: 308950/2011-9, 562171/2010-0 (AP), 565046/2010-1, 303545/ 2010-0 (HZ). *Correspondence to: Hussam Zaher, Museu de Zoologia da Uni- versidade de S~ ao Paulo, Avenida Nazar e 481, Ipiranga, S~ ao Paulo 04263-000, Brazil. E-mail: hussam.zaher@gmail.com Received 2 December 2012; Revised 24 July 2013; Accepted 14 August 2013. Published online 11 October 2013 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/jmor.20199 V C 2013 WILEY PERIODICALS, INC. JOURNAL OF MORPHOLOGY 275:87–99 (2014)