Entomologica, Bari, 40 (2006-2007): 117-138 MIFSUD D.1, MONFREDA R.2, DE LILLO E.2 Eriophyoid mites (Acari: Prostigmata: Eriophyoidea) from the Maltese Islands (Central Mediterranean): new reports and a preliminary check-list ABSTRACT In the 20th Century, about 20 species of eriophyoids were listed for the Maltese Islands but these reports were entirely based on plant gall surveys. In these last four years, plant collections were made in order to investigate the species of eriophyoids present in Malta and Gozo. Most of the earlier reports have been confirmed and eight species were found to be new for the Maltese islands: Aceria caulobia (Nalepa) gall- making on Suaeda vera Gmelin; Aceria onychia (Nalepa) on Phlomis fruticosa L.; Aceria sheldoni (Ewing) on lemon; Aculus tetanothrix (Nalepa) gall-making on Salix sp.; Cecidophyopsis hendersoni (Keifer) on yucca; and three species associated with olive, Ditrymacus athiasella Keifer, Oxycenus maxwelli (Keifer) and Tegolophus hassani (Keifer). Additional remarks were included for Acalitus phloeocoptes (Nalepa), collected on cherry plum, whose earlier Maltese record was doubtful. A complete morphometric description of Aceria carlinae (Nalepa) is here provided. Key words: faunistic survey, eriophyoids, new records, Malta. INTRODUCTION The Maltese Islands are a group of low lying islands situated in the Central Mediterranean Basin. Although the total surface area is small (c. 316 km2) when compared to other islands/territories in the Mediterranean, and despite the high population density (over 1,200 persons/km2) and negative impacts of the tourist industry, the islands still harbour an array of natural habitats with more than 900 species of flowering plants. Due to the strategic position of the Maltese Islands, several groups of organisms have been studied and compared to those found in nearby territories. This is not the case with the eriophyoid fauna of Malta which was never studied as such. The Eriophyoid fauna of the Maltese Islands has never been studied in detail, and earlier data came from the so-called cecidological papers where eriophyoids were Dattiloscritto accettato il 13 luglio 2008. 1 Department of Biology, JC-University of Malta, Msida, Malta. E-mail: [email protected] 2 Dipartimento di Biologia Agro-forestale e Ambientale, Entomological and Zoological Section, Agricultural Faculty, University of Bari, via Amendola, 165/A, I-70126 Bari, Italy. E-mail: [email protected], [email protected] –– 118 –– primarily identified from visual symptoms on host plant species. The well-known cecidologist HOUARD (1913) listed only Aceria carlinae (Nalepa), previously reported by MASSALONGO (1911) who also found an unidentified species on Galium murale (L.) All. and Sherardia arvensis L. BORG (1922) in his book entitled “Cultivation and diseases of fruit trees in the Maltese Islands” mentioned some eriophyoid mites of economic importance but it is often not clear whether these records are authentically Maltese. CARUANA GATTO (1926) made a first attempt to compile an inventory of the gall-making organisms for the Maltese Islands and a number of eriophyoid mites were included. SALIBA (1963) in his compilation entitled “Insect pests of crop plants in the Maltese Islands” included five species of eriophyoid mites, probably basing himself on symptoms and on earlier records. HABER and MIFSUD (2007) recorded three eriophyoids new for Malta in a contribution regarding the arthropods associated with olive trees. In this last decade, the interest in Eriophyoidea has been always relevant (DE LILLO & SKORACKA, 2008) and a number of check-lists have been published for some Palaearctic countries (ÖZKAN et al., 1994; BERNINI et al., 1995; DE LILLO, 2004; PETANOVIC & STANKOVIC, 1999; SKORACKA et al., 2005; ERMAN et al., 2007; RIPKA, 2007). The eriophyoid check-list produced for the Fauna Europaea by one of the authors includes few species for Malta owing to the restricted diffusion of old published literature. Therefore, a first attempt to look specifically at Eriophyoidea occurring in the Maltese Islands was carried out and an updated list for the European check-list was produced. MATERIALS AND METHODS Sites in Malta and Gozo were surveyed and sampled for potential Eriophyoid symptoms and species presence. Specimens were recovered from plant materials by means of direct observations under a dissecting microscope and by using the extraction methods in MONFREDA et al. (2008). Mites were prepared and slide mounted according to Keifer’s method (KEIFER, 1975). LINDQUIST’s (1996) terminology and setal notation of the morphological details have been adopted for species description. All measurements of mites were made according to AMRINE and MANSON (1996), and are given in micrometers, and measurements are rounded off to the nearest integer; range values are given in brackets. The generic classification follows that of AMRINE et al. (2003) and HONG and ZHANG (1996). Material has deposited at the Dipartimento di Biologia e Chimica Agro-forestale e Ambientale (Di.B.C.A.), Entomological and Zoological Section, University of Bari, Italy and at the Department of Biology, University of Malta, Malta. Figures of –– 119 –– eriophyoid damages or galls included in this work were all taken in Malta using a FinePix S-5000 digital camera. Host plant names and their synonymies are in accordance with the Flora Europaea of the Royal Botanic Garden of Edinburgh, UK (http://rbg-web2.rbge.org.uk/FE/fe.html), and the Germoplasm Resources Information Network (GRIN) - Taxonomy for Plants, USDA-ARS, Beltsville, Maryland, USA (http://www.ars-grin.gov/cgi-bin/npgs/html/index.pl). Data on eriophyoid mites have been collected from de Lillo and Amrine personal database, and from the catalogue by AMRINE and STASNY (1994). Information on symptoms, host plant and localities of the species previously recorded are reported according to the scheme previously used for other catalogues (SKORACKA et al., 2005). LIST OF SPECIES Family ERIOPHYIDAE Nalepa, 1898 SUBFAMILY CECIDOPHYINAE KEIFER, 1966 TRIBE CECIDOPHYINI KEIFER, 1966 1. Cecidophyopsis hendersoni (Keifer, 1954) “Cecidophyes” hendersoni KEIFER, 1954; Bull. Calif. Dept. Agric., [E. S. 22], 43: 123- 124, pl. 236. TYPE DATA. Yucca glauca Nutt. (Agavaceae); Syracuse, Kansas (USA). GENERAL DISTRIBUTION. Australian, Nearctic, Palaearctic. MATERIAL EXAMINED. Malta: Zejtun, private house, 18.ii.2006, on Yucca sp. (cultivated indoor), leg. D. Mifsud; Hal Lija, Plant Biotechnology Centre, 9.iii.2006 on Yucca sp. (cultivated indoor), leg. D. Mifsud; Msida, University of Malta (Junior College), 27.iii.2008 on Yucca sp. (cultivated indoor), leg. D. Mifsud. RELATION TO THE HOST. Vagrant. The mites inhabit lamina of outer leaves and cause browning, when highly infested, along with the presence of a whitish powder including live, dead mites, and their exuviae (Fig. 1a). REMARKS. New record for the Maltese Islands. This species has been reported for New Zealand, Poland, USA (California, Georgia and Kansas) and Yugoslavia and displays a patch distribution which could depend on the nursery trade of the ornamental plants and it is expected to be wider than that known at present. The mite was previously collected also on Y. guatemalensis Baker (originally listed as Y. elephantipes Regel) (LABANOWSKI, 1999) and Y. gloriosa L. (PETANOVIC & STANKOVIC, –– 120 –– Fig. 1 - Plant damage and plant-galls caused by eriophyoid mites: a) Cecidophyopsis hendersoni on Yucca sp.; b) Acalitus phloeocoptes on cherry plum; c) Aceria carlinae on Atractylis gummifera; d) Aceria caulobia on Sueda vera; e) Aceria sheldoni on lemon fruit; f) Aceria stefanii on Pistacia lentiscus; g) Aculus anthobius on Galium sp.; h) Aculus tetanothrix on Salix alba; i) Phyllocoptruta oleivora on lemon fruit. –– 121 –– 1999). TRIBE COLOMERINI NEWKIRK ET KEIFER, 1975 2. Colomerus vitis (Pagenstecher, 1857) Phytoptus vitis PAGENSTECHER, 1857; Verh. Naturh.-med. Ver., Heidelberg 1(2): 51; NALEPA, 1890 - Sitzb., 99(2): 57-58, pl. 7, figs 1-2. TYPE DATA. Vitis vinifera L. (Vitaceae); Germany (presumed). GENERAL DISTRIBUTION. Australian, Ethiopian, Nearctic, Neotropical, Oriental, Palaearctic. MATERIAL EXAMINED. Malta: Ghammieri, 24.vi.2006, on V. vinifera (cultivated), leg. D. Mifsud; Rabat, 16.viii.2008, on V. vinifera (cultivated), leg. D. Mifsud. RELATION TO THE HOST. Gall-making. It causes the formation of hemispherical bulges on grapevine upper surface of leaves; corresponding areas on the under surface of the leaves are concave and host a felty mass of hairs (erineum). These hair masses are initially white but they turn to a reddish brown colour during the growing season. REMARKS. BORG (1922) and CARUANA GATTO (1926) listed Landois as authorship of the species. This combination was synonymized to Pagenstecher by KEIFER (1944). Recent genetic investigation resolved the taxonomical status of the bud and blister strains, identifying two closely related but distinct species which cause these different symptoms (CAREW et al., 2004) and which need to be morphologically separated, yet. Colomerus vitis is a very common species distributed all over the Maltese Islands (BORG, 1922; CARUANA GATTO, 1926; SALIBA, 1963). SUBFAMILY ERIOPHYINAE NALEPA, 1898 TRIBE ACERIINI AMRINE ET STASNY, 1994 3. Acalitus phloeocoptes (Nalepa, 1890) Phytoptus phloeocoptes NALEPA, 1890; Sitzb., 99(2): 54-55, pl. 6, figs 4-5, pl. 7, fig. 6. TYPE DATA. Prunus domestica L. (Rosaceae); not stated by the author; Austria (presumed). GENERAL DISTRIBUTION. Nearctic,