245 10 Biodiversity of Orthoptera Hojun Song Department of Entomology, Texas A&M University, College Station, Texas, USA With more than 26,000 extant species, the 10.1 Taxonomic Classification Orthoptera are the most diverse order among and Phylogeny the polyneopteran insect lineages (Grimaldi and Engel 2005, Eades et al. 2015). The order includes The monophyly of the Orthoptera has been familiar singing insects, such as crickets and supported by morphological and molecular data katydids, as well as often‐devastating pests, such (Chopard 1949, Sharov 1968, Kevan 1982, Flook as grasshoppers and locusts (Gangwere et al. et al. 1999). Among many morphological and 1997). Orthopteran insects have diversified into physiological characters that define the Orthoptera numerous lineages that occupy every conceiva- (Chopard 1920; Slifer 1939; Judd 1947; Ragge ble terrestrial habitat outside the polar regions 1955; Dirsh 1957, 1973; Blackith and Blackith and play integral roles in their ecosystems 1968; Baccetti 1987b; Eades 2000), the presence of (Uvarov 1966, Kevan 1982). Such diversity in a cryptopleuron, developed from the lateral exten- form and function has attracted researchers who sion of the pronotum over the pleural sclerites use these insects as model systems for studying (Grimaldi and Engel 2005), and the jumping hind anatomy, bioacoustics, chemical ecology, evolu- legs are major diagnostic characters (Kevan 1982). tionary ecology, life‐history traits, neurobiology, Molecular phylogenetic studies based on riboso- physiology, and speciation (Uvarov 1966, 1977; mal RNA genes and mitochondrial genes have Baccetti 1987a; Chapman and Joern 1990; supported the monophyly of the order (Flook et al. Gangwere et al. 1997; Pener and Simpson 2009). 1999), and, most recently, a phylogenetic study In this chapter, I present a general overview of based on complete mitochondrial genome data the systematics of the Orthoptera, as well as and four nuclear genes (Song et al. 2015) also diversity in form and function in the order, and strongly supports monophyly. However, the phy- provide a brief synopsis of each of the known logenetic position of the Orthoptera within the families. A number of excellent reviews have been Polyneoptera is still not fully resolved. Based on informative in compiling this chapter: Uvarov extensive fossil data, the Paleozoic Orthoptera (1966, 1977) and Chapman and Joern (1990) on were thought to be closely related to the general biology, especially of grasshoppers; and Phasmatodea (Sharov 1968). Wheeler et al. (2001) Kevan (1982), Vickery (1997), and Grimaldi and presented a cladistics analysis based on morphol- Engel (2005) on taxonomic diversity. ogy and ribosomal RNA data and also found a Insect Biodiversity: Science and Society, Volume II, First Edition. Edited by Robert G. Foottit and Peter H. Adler. © 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd. 246 Insect Biodiversity: Science and Society sister relationship between the Orthoptera and 2013; Mugleston et al. 2013; Zhang et al. 2013; Phasmatodea. However, the most recent phylog- Chintauan‐Marquier et al. 2016; Song et al. enomic study by Misof et al. (2014) found the 2015). The most notable study was by Flook Orthoptera to be sister to a clade consisting of the et al. (1999), who produced the first modern Mantophasmatodea, Grylloblattodea, Embiodea, phylogeny of the Orthoptera, based on 31 in‐ Phasmatodea, and Dictyoptera. A more compre- group taxa representing all major lineages and hensive phylogenetic study of the Polyneoptera is three ribosomal loci; they also reclassified some required to fully resolve the position of the superfamilies. In 2015, Song et al. published a Orthoptera relative to other members. large‐scale molecular phylogeny based on The taxonomic classification of the Orthoptera complete mitochondrial genome data and four has a tumultuous and complex history, as different nuclear loci to thoroughly test the previous taxonomists proposed conflicting classification classification schemes, and proposed a new schemes based on different character sets, such as phylogeny‐based natural classification, which is fossil wing venation (Zeuner 1942, Sharov 1968, adopted in this chapter. According to this new Gorochov 1995a), internal organs (Slifer 1939, classification scheme, the Orthoptera consists of Judd 1947, Dirsh 1957, Baccetti 1987b), external two monophyletic suborders, the Ensifera and morphology (Blackith and Blackith 1968), and the Caelifera. The Ensifera consist of two infraorders, male phallic complex (Chopard 1920, Ander 1939, the Gryllidea and Tettigoniidea, and are charac- Roberts 1941, Dirsh 1973, Amédégnato 1974, terized by long, flagellate antennae that are often Eades 2000). Based on the early application of longer than the length of the body, and a sword‐ numerical taxonomy, Blackith and Blackith (1968) like or needle‐like female ovipositor. The Gryllidea suggested that the phenetic differences between include the superfamilies Grylloidea and the Ensifera and Caelifera were greater than Gryllotalpoidea, whereas the Tettigoniidea include among other orthopteroid (polyneopteran) orders the Schizodactyloidea, Rhaphidophoroidea, and raised the possibility of treating them as two Hagloidea, Stenopelmatoidea, and Tettigonioidea. distinct orders. Kevan (1973) went one step fur- Collectively, the Ensifera include about 14,000 ther and elevated the Ensifera as a separate order described species. The Caelifera also consist of and called it the Grylloptera, while redefining the two infraorders, the Tridactylidea and Acrididea, Caelifera as Orthoptera sensu stricto. In 1975, the and are characterized by shorter antennae and higher classification of the Orthoptera reached its a female ovipositor with only two valvular most chaotic state when Dirsh (1975) proposed a pairs. The Tridactylidea include the superorder Orthopteroidea with 10 new orders. Tridactyloidea, whereas the Acrididea include However, most taxonomists today agree that the eight superfamilies: Tegtrigoidea, Eumastacoidea, Orthoptera should be treated as a single order. Proscopioidea, Tanaoceroidea, Pneumoroidea, These different classification schemes were Trigonopterygoidea, Pyrgomorphoidea, and pre‐cladistic and mostly based on the taxono- Acridoidea. The Caelifera include more than mists’ interpretations of the characters and rela- 11,000 described species. The higher‐level rela- tionships. From the late 1990s, a series of modern tionships among different superfamilies in the cladistic studies using morphological or molecu- Orthoptera are now well resolved (Fig. 10.1). lar data were published, which objectively tested the previous classification schemes (Gwynne 1995; Flook and Rowell 1997; Chapco et al. 1999, 10.2 Diversity 2001; Flook et al. 1999, 2000; Desutter‐ and Distribution Grandcolas 2003; Jost and Shaw 2006; Matt et al. 2008; Legendre et al. 2010; Zhou et al. 2010; When establishing a robust classification Chintauan‐Marquier et al. 2011; Leavitt et al. scheme, a comprehensive synonymic catalog is 10 Biodiversity of Orthoptera 247 Figure 10.1 Phylogenetic relationships among major superfamilies of Orthoptera. The topology is based on that of Song et al. (2015). an invaluable tool. For the Orthoptera, the the Grylloidea, and, subsequently, a total of eight Orthoptera Species File (OSF) (Eades et al. 2015) volumes to cover all the Orthoptera were pub- is the most definitive catalog available today. The lished by 2000. In 1997, Otte and Piotr Naskrecki, concept of the OSF, a collection of all taxonomic an expert in Tettigoniidae systematics, devel- and synonymic information for the Orthoptera, oped the first online version of the OSF. Then in was developed by Daniel Otte, one of the most 2001, David Eades, an expert in Acrididae sys- important and prolific orthopteran taxonomists tematics, joined and further developed it using a of the 20th century (Song 2010). Otte published relational database, which ultimately led to the the first paper volume of OSF in 1994 to cover current version of the OSF – available to the 248 Insect Biodiversity: Science and Society public at http://orthoptera.speciesfile.org/. For (including Mexico), Central and South America, all known species of orthopterans, the OSF Temperate Asia, Tropical Asia, Australia, Europe, online contains as complete as possible syno- Pacific, and Antarctica. In each region there are nymic and taxonomic information, citations and additional layers of finer details, such as coun- references, images and sound recordings, maps, tries and states. For instance, using a complex specimen collecting records, and identification search, one can find how many species have been keys. As of March 2015, the OSF online contains recorded from North America or the North full information on 26,690 valid species (includ- Central United States (10 US states). When such ing fossils), 43,970 scientific names, 192,500 an analysis is performed for the Orthoptera and citations leading to 13,000 references, 81,300 each of the suborders, patterns begin to emerge images, 1300 sound recordings, 89,500 speci- (Fig. 10.2). When the Orthoptera as a whole are men records, and keys to 2800 taxa. The under- considered, Central and South America harbor lying software for the OSF is the Species File 22% of the entire known diversity, followed by Software (SFS), which relies on a powerful rela- Tropical Asia (21%), Africa (20%), and Temperate tional model database server (Microsoft SQL Asia (17%). For Central and South America,