Abstract
Madagascar is one of the world hotspots for endemics, and its rapidly changing habitats accelerate the need for their study and conservation. Orthopterans, mantids, phasmids, and cockroaches were sampled in five main habitats (savanna and shrubland, semiarid spiny forest, rainforest, mountain grass- and shrubland, and cultivated habitats) in central and southern Madagascar (41 sites, 0–2250 m a.s.l.) with the aim of getting the first data on their diversity and distribution along environmental gradients shortly after the rainy period. Samples were collected primarily by sweeping herb and shrub vegetation along transects 100 m long and 1–2 m wide (5–8 transects/site) and supplemented using other techniques. Altogether 117 species of orthopteroid insects were found (94 Orthoptera, 7 Mantodea, 4 Phasmida, and 12 Blattodea), among them two katydid species which had been recently described as new to science (Mimoscudderia longicaudataHeller & Krištín, 2019,Parapyrrhicia leucaHemp & Heller, 2019). High species diversity was documented: altogether 63 species (53.8%) were present at only one site, 14 (12%) at two sites, and 5 species (4.2%) at three sites. Nonmetric multidimensional scaling analysis on species composition did not clearly separate the assemblages of the sampled sites. Species assemblages from four habitats overlapped due to their similarity. Only assemblages from the rainforest sites were partially separated from the other sites. Cultivated habitats were characterized by the most frequent (F > 50%) and abundant grasshopper species, such asAcorypha decisa,Aiolopus thalassinus rodericensis,Oedaleus virgula,Gelastorrhinus edax,Gymnobothrusspp,. andAcrotylusspp. We found a significant association between habitat management and species rareness, where the number of rare species was higher in natural/unmanaged habitats. However, we found no association between habitat management and the number of endemic species. For several species we provide the first detailed data on their localities and habitat.
Highlights
Madagascar represents one of the most important hotspots of endemism on Earth (Myers et al 2000, Ganzhorn et al 2001, Goodman and Benstead 2005, Vences et al 2009)
We focused on 1) the diversity and distribution of orthopteroids along environmental gradients at 41 sites in central and southern Madagascar and 2) assemblage structure of orthopteroid insects in five different habitats and altitudes (0–2 250 m a.s.l.)
A higher endemism rate is shown by Caelifera, in which 58 of the 68 identified species are endemic to Madagascar (85.3%), two species are related to African fauna, two species to Indomalaya, and six are widely distributed, e.g., migratory species Cyrtacanthacris tatarica, Acrotylus patruelis, Locusta migratoria, and Gastrimargus africanus (Suppl. material 1)
Summary
Madagascar represents one of the most important hotspots of endemism on Earth (Myers et al 2000, Ganzhorn et al 2001, Goodman and Benstead 2005, Vences et al 2009). Orthopteroid insects are among the most important bio-indicators of the status of integrity of natural habitats, especially habitats with small plot sizes (Gerlach et al 2013). They are excellent study systems, e.g., for the coevolution of native and introduced species on some of the Mascarene Islands (Boyer and Rivault 2003). Orthopterans in Madagascar include a large percentage (ca 80–90%) of endemic species (Descamps and Wintrebert 1965, Dirsh and Descamps 1968, Descamps 1971, Wintrebert 1972, Devriese 1991, 1995, Braud et al 2014, etc.); a similar situation is known in the phasmids (Bradler and Buckley 2018) and mantids (Ehrmann 2002). The ensiferans are a less-known orthopteran group in Madagascar, e.g., Phaneropterinae, Pseudophyllinae, Conocephalinae (Carl 1914, Ragge 1964, Gorochov and Llorente 2004, Ünal and Beccaloni 2008, 2017, Gorochov 2009, Heller et Journal of Orthoptera Research 2019, 28(2)
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