A total of 18 spider mite species belonging to 10 genera of the family Tetranychidae (Acari: Prostigmata) are reported from different provinces of Saudi Arabia (SA). Among these, two new species, Sonotetranychus madinahensis sp. nov. and Tetranychus salicornicus sp. nov., belonging to the subfamily Tetranychinae are described and illustrated. Also, five genera and 11 species are new to the mite fauna of SA. The distribution and host data of all recorded species in the current study are provided. A key to all spider mite species of SA is provided as well as a key to the species of the armenychus species group of the genus Tetranychus Dufour, based on males. www.zoobank.org/urn:lsid:zoobank.org:pub:C41BB3ED-99D5-4DCF-B557-09526FA7D56B

In the present study, we evaluated the effect of management practices, fruit season, host habitats (young and old fronds, date fruits and grasses), and temperature on the phenology and abundance of the date palm mite (DPM). The study was conducted in two date palm orchards (two plots each): a managed and an unmanaged plot. The phenology of DPM was assessed based on adult cumulative mite days (ACMDs), while mean mite density was used to assess the mite abundance on different host habitats. The ACMDs and mean mite density were significantly different between managed and unmanaged plots on different host habitats in both fruiting and off-seasons. The date fruits had highest ACMDs during fruiting season. While young fronds had significantly higher ACMDs than on old fronds an grasses during both seasons in both plots.. The temperature and season type significantly affected the mean density of DPM eggs and adults. There was a significant effect of host habitats mean density of DPM eggs and immatures. Based on the adult phenology and abundance of DPM, the mite overwinters in young fronds and aerial offshoots of infested date palm trees. These overwintering DPM caused the seasonal date fruit infestation, each year. Additionally, different phytophagous and predatory mites, which co-occur with DPM, and were found on different host habitats affected the phenology and abundance of DPM. Moreover, the change in DPM body color was related to the host habitat that they fed in. Exceptionally, the brown color of females collected during the winter season could be due to physiological changes due to low temperature. In DPM males collected from different host habitats throughout the study, some morphological variations in the width of the knob, height of the hook, and the angle between the knob axis and dorsal margin of the shaft were also recorded. The results of this study suggest that young fronds and grasses are the suitable sites for DPM survival and overwintering. Hence, the management practices, early in the fruit season and/or during off fruit winter months, should be directed towards these habitats. These could provide efficient reduction in seasonal infestation of DPM.

The superfamily Phytoseioidea (Acari: Mesostigmata) from Saudi Arabia: a new species, new records and a key to the reported species

Five stigmaeid species belonging to the genus Agistemus Summers (Acari: Trombidiformes: Stigmaeidae) are recorded from different regions of Saudi Arabia. Among these, Agistemus jawadi sp. nov., inhabiting on Ziziphus spina-christi (L.) Desf. is described and illustrated based on female. Two species, A. fleschneri Summers and A. aimogastaensis Leiva et al. are recorded as new to the fauna of Saudi Arabia. Two species A. fleschneri and A. exsertus Gonzalez-Rodriguez are re-described based on adult females. Moreover, Agistemus species are categorized in two species groups; fleschneri and terminalis based on one and two pairs of aggenital setae respectively. A key to the world species of the genus Agistemus is provided. Three species, Agistemus rafiqi Khan et al., A. rawalpindiensis Khan et al. and A. layyahensis Khan et al. are considered as junior synonyms of Agistemus garrulus Chaudhri et al. 1974.

This paper reports on 35 species and 33 genera belonging to 18 families of the order Mesostigmata, collected from different provinces of Saudi Arabia. Among these, eight families, 21 genera and 30 species, mostly collected from date palm agroecosystem, are new to the fauna of Saudi Arabia. Five species reported previously are also recorded in this study. The collection data and distribution of all species recorded in this study as well as those reported previously are given. A comprehensive key to the females of the mesostigmatic mites reported from Saudi Arabia, except the Phytoseioidea, is provided.