TERMS OF USE This pdf is provided by Magnolia Press for private/research use. Commercial sale or deposition in a public library or website is prohibited. Zootaxa 2414: 1–26 (2010) ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ Article ZOOTAXA Copyright © 2010 · Magnolia Press ISSN 1175-5334 (online edition) Key to the Species of Cosmetidae (Arachnida, Opiliones) of Central America, with Notes on Penis Morphology and Sexual Dimorphisms VICTOR R. TOWNSEND, JR.1,5, CARLOS VÍQUEZ2, PETER A. VANZANDT3, & DANIEL N. PROUD4 1Department of Biology, Virginia Wesleyan College, 1584 Wesleyan Drive, Norfolk, Virginia 23502 USA. E-mail: [email protected] 2INBio, Apdo. 22-3100, Santo Domingo, Heredia, Costa Rica. E-mail: [email protected] 3Department of Biology, Birmingham-Southern College, 900 Arkadelphia Road, Birmingham, Alabama 35254 USA. E-mail: [email protected] 4Department of Biology, University of Louisiana at Lafayette, Box 42451, Lafayette, Louisiana 70504–2451 USA. E-mail: [email protected] 5Corresponding author Abstract To facilitate identification of harvestmen of the family Cosmetidae in Central America, we developed dichotomous keys that distinguish the 33 known genera and the 133 described species for this region. Couplets are based upon characters found in the literature and examinations of museum specimens. Important characters include the number of tarsomeres on leg I, armature of the dorsal scutum, free tergites and legs, as well as the coloration and relative length of the body and legs. In addition, we provide a summary of sexually dimorphic features and comment on the potential usefulness of penis morphology and coloration as characters for distinguishing taxa. Key words: Arachnida, Central America, Cosmetidae, Laniatores, Opiliones, taxonomic key Resumen Para facilitar la identificación de Opiliones de la familia Cosmetidae en Centroamérica, nosotros desarrollamos una clave dicotómica que distingue los 33 géneros conocidos y las 133 especies descritas para esta región. Cada par de opciones esta basadas en caracteres que se encontraron en la literatura y revisión de especímenes de museo. Entre los caracteres de importancia están el número de tarsómeros de la pata I, armadura de el escudo dorsal, tergitos libres y patas, así como la coloración, tamaño relativo del cuerpo y patas. Además, nosotros suministramos un resumen de caracteres sexuales dimorficos y comentarios en la utilidad potencial de la morfología del pene y su coloración como caracter para distinguir taxones. Palabras clave: Arachnida, Centroamérica, Cosmetidae, Laniatores, Opiliones, clave taxonómica Introduction In Neotropical forests, harvestmen (Arachnida, Opiliones) are among the most commonly encountered arthropods, particularly after dusk, when individuals are frequently seen in the leaf litter or climbing tree buttresses, lianas and other vegetation (Acosta & Machado 2007; Townsend et al. 2008). Most species are generalist predators, feeding upon a diverse array of invertebrates (Acosta & Machado 2007), but their diets may also include fungi, flowers, or fruits (Machado & Pizo 2000). In contrast to insects and spiders (for a review see Bragagnolo et al. 2007), harvestmen have seldom been used to assess the impact of forest management practices. In the Atlantic forests of Brazil, the abundance and presence of rare species of harvestmen from the families Gonyleptidae and Sclerosomatidae were strongly affected by the absolute size Accepted by A. Perez-Gonzalez: 24 Feb. 2010; published: 30 Mar. 2010 1 TERMS OF USE This pdf is provided by Magnolia Press for private/research use. Commercial sale or deposition in a public library or website is prohibited. and relative quality of forested patches (Bragagnolo et al. 2007). In temperate spruce and fir forests of North America, the abundance of harvestmen of genus Leiobunum (Sclerosomatidae) was significantly reduced in clear-cut strips (Jennings et al. 1984). Field studies of harvestmen in Central America have the potential to provide important insights into the efficacy of management practices, particularly those aimed at maintaining or restoring forested habitats (Kremen et al. 1993; Bragagnolo et al. 2007). Potential advantages of using these arachnids as ecological indicators include the richness of species richness exhibited by the group (239 described species in Central America) and the high endemism exhibited by harvestmen in tropical forests (Pinto-da-Rocha et al. 2005). Presently, the known harvestmen fauna of Central America (Roewer 1953; Kury 2003) features representatives of the families Cosmetidae (33 genera, 133 species), Cranaidae (2 genera, 3 species), Gonyleptidae (4 genera, 11 species), Manaosbiidae (4 genera, 4 species), Samoidae (3 genera, 4 species), Sclerosomatidae (4 genera, 41 species), Stygnopsidae (1 genus, 2 species), Stygnommatidae (1 genus, 5 species) and Zalmoxidae (6 genera, 36 species). A significant challenge to the use of harvestmen assemblages as ecological indicators in Central America is the fact that relatively little or nothing is known about their natural history (but see Mora 1990; Donaldson and Grether 2007a, 2007b) or geographic ranges (Roewer 1953; Kury 2003). There is also a significant bias with respect to the number of species recorded for each country (Roewer 1953; Kury 2003). The harvestmen fauna of Costa Rica (121 species) is the best characterized, whereas the total numbers of species for Belize (30 species), Panama (48 species) and Guatemala (51 species) probably represent considerable underestimates of the actual number of species present. The faunas of El Salvador (15 species), Honduras (9 species), and Nicaragua (2 species) are poorly known. Although excellent guides for identifying families have recently been published (Cokendolpher et al. 2007; Pinto-da-Rocha 2007), there are still no published taxonomic keys that distinguish species of harvestmen for Central America. Therefore, we developed taxonomic keys for the Cosmetidae, the most diverse family in the region (Kury 2003). Cosmetid harvestmen are easily distinguished from species of other families on the basis of the morphology of the pedipalp (Kury & Pinto-da-Rocha 2007). In cosmetid harvestmen, the femur of the pedipalp is laterally compressed and the tibia is spoon-shaped (Fig. 1). The Cosmetidae is endemic to the Western Hemisphere, with species occurring from the southern U.S. to Argentina with the highest levels of diversity concentrated in Mexico, Central America, the Caribbean, and northern South America (Kury 2003; Kury & Pinto-da-Rocha 2007). The Cosmetidae has traditionally been divided into two subfamilies on the basis of the morphology of the tarsal claws on legs III and IV (Roewer 1912; Kury & Pinto-da-Rocha 2007). Members of the Discosomaticinae (10 genera, 29 species) have pectinate claws, Cosmetinae (116 genera, 681 species) have smooth claws (Kury, 2003). All described cosmetid species in Central America are members of the Cosmetinae (Kury 2003). In the keys, we used the number of tarsomeres on leg I (Table 1) and the armature on the dorsal scutum (Table 2) as major characters because these features have been extensively used in taxonomic studies of the Cosmetidae from Central America (Roewer 1912, 1923, 1927; Goodnight & Goodnight 1953a, 1953b). The segmentation of the tarsi to define genera has been criticized (e.g., Kury et al. 2007) because the numbers of tarsomeres for especially legs II–IV have been observed to exhibit considerable intraspecific variation. In our keys, we avoided using tarsomere numbers for legs II–IV as characters, but we included published reports (if known) for ranges for observed tarsal formulae (TF: denoted as the number of tarsomeres occurring on each leg, i.e., Leg I: Leg II: Leg III: Leg IV). We also used characters related to body and leg coloration as well as relative leg size and total body length for species identification. Although body shape has shown considerable potential for use as an informative character in evaluating monophyly in several Neotropical genera (Kury et al. 2007), we did not use this character in our key because most species from Central America exhibit α or β shapes and we had difficulty with reliably distinguishing these body shapes. 2 · Zootaxa 2414 © 2010 Magnolia Press TOWNSEND ET AL. TERMS OF USE This pdf is provided by Magnolia Press for private/research use. Commercial sale or deposition in a public library or website is prohibited. TABLE 1. Number of tarsal segments on leg I for the known genera of Cosmetidae in Central America. Tarsomeres Genera 5 Bokwina, Boneta, Holovonones, Kevonones, Metacynorta, Paravonones, Tajumulcia, Vonones, Vononesta, Vononula 6 Acromares, Cynorta, Cynortellana, Cynortoperna, Cynortula, Erginoides, Erginulus, Eucynorta, Eucynortella, Eucynortoides, Eucynortula, Eugnidia, Flirtea, Metarhaucus, Metavonones, Paracynorta, Reimoserius 7 or more Cosmetus, Eupoecilaema, Meterginus, Paecilaema, Paecilaemana, Poecilaemula TABLE 2. Armature of the abdominal scutum for the Cosmetinae from Central America. Cynorta, Eucynortula, and Paecilaema are not included because these genera exhibit more than one pattern of dorsal armature. -- = unarmed, vv = paired tubercles, V = single, median tubercle. Area I Area II Area III Area IV Taxa -- -- -- -- Erginoides, Eucynortella, Kevonones, Vononula -- -- vv -- Acromares, Bokwina, Boneta, Erginulus, Eucynorta, Metavonones, Paecilaemana, Paravonones, Poecilaemula, Vonones -- -- V -- Cosmetus vv -- vv -- Cynortellana, Cynortula, Eugnidia, Eupoecilaema,