Ptyctimous mites (Acari, Oribatida) of Madagascar and neighbouring islands

Abstract

Diagnoses of 111 ptyctimous species known from Madagascar and neighbouring islands Seychelles, Mauritius, Comoros and Reunion (MAG) are presented. Additionally, 44 species have been redescribed based on type material. Four species are new for the Afrotropical Region, and nine are new for MAG. Keys for identification of species and higher taxa have also been constructed. The percentage ratio of Protoplophoridae to Archoplophoridae: Mesoplophoridae: Euphthiracaroidea is 2: 5: 27: 66. The proportions of species representing two families – the more primitive Oribotritiidae and less primitive Euphthiracaridae of Euphthiracaroidea are similar. Within Phthiracaroidea the more primitive Phthiracaridae are less abundant than Steganacaridae. Among Euphthiracaridea the most abundant are the genera: Oribotritia and Acrotritia, while from among Phthiracaroidea by far the most abundant species is the genus Notophthiracarus, while Hoplophorella and Phthiracarus are also rather abundant. The proportions of the number of species from higher taxa are usually similar to those in the fauna of other zoogeographic regions in the southern hemisphere. The fauna of MAG is characterised by a high number of related species (88), endemic 68 (61 %) and indigenous 20 (18%) as well as a relatively high number of pantropical species (11). All these proportions of species are similar to other zoogeographic Regions of the southern hemisphere: Afrotropical, Oriental, Australasian and Neotropical. The fauna of MAG (111 species) is closer to that of the Afrotropical Region (200 species) (15% common species) than to that of the Oriental Region (262 species) (4% common species). A significant number of widespread species (14) occur in the faunas of MAG and the Oriental Region, and four of them seem to be of Oriental origin. The fauna of Madagascar and neighbouring islands shows no similarity to that of India. In 171 soil samples collected in 2010-2015 on Madagascar the number of species found was 78. The eastern part of the island is the most abundant in species – 67 species; the northern part is less abundant – 53 species and, central part is the least abundant – 34 species. The highest number of endemites was found in the fauna of the eastern and central parts of Madagascar. The unique character of Madagascan fauna is the presence of a high number of endemic species among the dominant species and species of high frequency. In the new material the most abundant and most frequent species is the endemic Oribotritia striata, followed by five endemic species Protophthiracarus araios, Oribotritia mahunkai, Indotritia paulyi, Notophthiracarus similis, Notophthiracarus zebrus and two pantropical species Acrotritia vestita and Indotritia javensis. The fauna of neighbouring islands does not show an Oriental origin and is closely related to that of Madagascar, more than half of the number of species (17) occur also in Madagascar but nearly a quarter of the species are endemites. The fauna of MAG has been compared 12 years after the former report, some similarities and differences were found.