Tarsonemini, Canestrini & Fanzago, 1877

Magowski, Wojciech L., Ahadiyat, Ali & Ostovan, Hadi, 2017, Tarsonemid mites (Acari, Heterostigmatina) found in association with bark beetles (Insecta, Curculionidae, Scolytinae) in Iran, Turkish Journal of Zoology 41 (2), pp. 323-328 : 324-326

Tribe: Tarsonemini Canestrini and Fanzago, 1877 Genus: Tarsonemus (T.) Canestrini and Fanzago, 1876

T. (T.) crassus ( Schaarschmidt, 1959) : 1♀ on Ulmus sp. , Rasht, Guilan Province, 31 May 1997, leg. H. Ostovan; 1♀, 4♂♂, 1 lv in gallery of S. scolytus on Ulmus sp. , Rasht, Guilan Province, 31 May 1997, leg. H. Ostovan; 1♂ in gallery of S. multistriatus on Ulmus sp. , Rasht, Guilan Province, 1 June 1997, leg. H. Ostovan; 1♂, 1 lv in gallery of S. scolytus on Ulmus sp. , Rasht, Guilan Province, 1 June 1997, leg. H. Ostovan; 1♀ in gallery of S. scolytus on Ulmus sp. , Rasht, Guilan Province, 3 June 1997, leg. H. Ostovan; 1♀ phoretic on S. multistriatus on Ulmus sp. , Tehran (Nārmak region), Tehran Province, 28 May 1997, leg. H. Ostovan.

T. (T.) fusarii Cooreman, 1941: 1 ♂ in gallery of S. multistriatus on Ulmus sp. , Tehran, Tehran Province, 7 July 1997, leg. H. Ostovan; 1♀ insect host not mentioned, most probably Scolytus sp. on Ulmus sp. , location not indicated (probably Tehran), 15 April 1997, leg. H. Ostovan; 1♀ phoretic on S. multistriatus on Ulmus sp. , location not indicated (probably Tehran), 16 April 1997, leg. H. Ostovan; 1♀ in gallery of S. multistriatus on Ulmus sp. , Tehran (Sa’adat Abad region), Tehran Province, 16 April 1997, leg. H. Ostovan; 1♀ in gallery of S. multistriatus on Ulmus sp. , Tehran (Sa’adat Abad region), Tehran Province, 27 May 1997, leg. H. Ostovan.

T. (T.) spp. indet.: 1♀ insect host not indicated, on Ulmus sp. , location not indicated (probably Tehran), 20 April 1997, leg. H. Ostovan; 1♀ in gallery of S. multistriatus on Ulmus sp. , Tehran (Sa’adat Abad region), Tehran Province, 27 May 1997, leg. H. Ostovan.

Identification of the mite material collected in this study has been difficult for multiple reasons. Most importantly, the taxonomy of nearly all tarsonemid speciesgroups involved is insufficiently understood. The majority of publications originating from the past century contain a number of issues, of which outdated descriptions are the most challenging. A serious effort to sort out the Nearctic fauna of bark beetle tarsonemid associates by Smiley and Moser (1974) was only a partial success. Insufficient insight into some morphological characters resulted in confused diagnoses. Those vague diagnostics and outdated publications (e.g., Vitzthum, 1921; 1923) being the primary source of data make our identification of the Pseudotarsonemoides species less reliable. Furthermore, scarce records on the intraspecific variability in the genus Tarsonemus , particularly for T. crassus and T. fusarii , could render the identifications reported herein uncertain. Suski (1970), describing the male of T. crassus , contributed to amending its diagnostics, and Magowski and Moser (2003) updated its in-group classification, but still little is known of its natural variability. Specimens identified here as T. crassus differ in certain minor morphological characters from the current diagnostic standard. Tarsonemus fusarii , on the other hand, is a well-known and widespread species (see Kaliszewski and Sell, 1990). Samples from the present collectings reveal some atypical morphological variability with regards to its sejugal apodeme. Unlike T. crassus , T. fusarii is not an obligate associate of bark beetles. As the latter is found in a variety of terrestrial habitats (mostly soils and deteriorating organic substrates) one may speculate that this variability reflects the suboptimal conditions encountered in bark beetles galleries. In his original paper, Khaustov (2001) reported H. magowskii phoretic on Hypophloeus pini Panzer, 1799 ( Tenebrionidae ) and in galleries of Orthotomicus longicollis (Gyllenhal, 1827) . Thus, our record adds a new host, namely O. erosus . We observed a relatively high density of H. magowskii moving within the sawdust in galleries, whose individuals could occasionally be seen upon uropodine mites (probably of the genus Trichouropoda ); however, this association may be accidental (see Camerik, 2010a). Our finding of T. crassus represents the first extra-European record, associated with same beetle host as in Europe. This association appears more stringent and host-specific in nature and perhaps obligate ( Camerik, 2010b). The multitude of situations where T. fusarii is found suggests that the notion of “host affiliation” related to this species and bark beetles cannot be safely applied, even though some sparse records (e.g., Khaustov and Magowski, 2003) of co-existence with Scolytinae are known. Of the two species, namely T. crassus and T.fusarii , reported as phoretic in this study, the phoresy of the latter is questionable as a natural aptitude.

The present knowledge on identities of reported Irani- an species of tarsonemids co-occurring with bark beetles is summarized in the Table. It is conceivable that identifications of four recorded species should be re-examined in the light of recent taxonomic literature. Both Iranian records of “ T. ips ” (referred to in the Table as spp. nr. ips 1 and 2) in Ostovan and Kamali (1997) and Arabzadegh et al. (2012), respectively, were published prior to or unawarely of the revision of the subgenus Schaarschmidtia by Magowski (2010), and so the vital diagnostics of this compound group could have not been applied. As originally T. ips is known to be associated almost exclusively with pines in North and Central America ( Magowski, 2010), it is unlikely that two recorded populations found on elm or apple trees in Iran would represent that, or even one and the same species. Similarly, two other species of the T. minimax group ( T. triarcus and T. subcorticalis ) were recorded in Iran before the work by Magowski and Moser (2003). While T. triarcus seems to be an exclusively North American species, the identity of Eurasian populations of T. subcorticalis remains uncertain, as similarly has been realized in the case of two other closely allied Crimean populations of T. nr. endophloeus Lindquist, 1969 spp. 1 and 2 by Khaustov and Magowski (2003). Apart from T. fusarii , another two species, namely T. nr. bachmaieri and T. pseudolacustris (Table), are not regular associates of bark beetles. An indiscriminative method of material collecting (by examination of twigs and bark from trees occupied with bark beetles) provided an impression of a more intimate association, which may not be true.

Before the present study, six identified and one unidentified species of the family Tarsonemidae had been reported to be associated with bark beetles in Iran ( Ostovan and Kamali, 1997; Ahadiyat et al., 2004; Magowski et al., 2007; Magowski, 2010; Arabzadeh et al., 2012 – see Table), making it the most species-rich mite family in this habitat context (Ahadiyat, personal observations) in this country. Three tarsonemid species were reported in association with S. amygdali Guerin-Meneville 1847 , four with S. multistriatus and three with S. scolytus (Table). The results of our study increased the number of identified tarsonemid species to nine. It has also brought the total of the genus Tarsonemus species up to six, making it the most diverse genus among Acari associates of bark beetles in Iran. Among all the studied species of bark beetles, S. multistriatus appears the most suitable host, apparently presenting a set of optimal microhabitats for six identified species of Tarsonemidae . Pseudotarsonemoides innumerabilis is the only species (among those reported herewith) found in four provinces of Iran.

Nearly all tarsonemid species presented herewith (except for T. fusarii and P. innumerabilis ) are new to the Iranian fauna. Heterotarsonemus magowskii and H. hajekae are both reported worldwide for the second time; moreover, H. magowskii is the first extra-European record and H. hajekae the first extra-American record. Consequently, both Heterotarsonemus species represent first records from Iran and, in a wider context, from Asia.

Acknowledgments

We thank Dr Mikhail Mandelshtam ( Russian Academy of Sciences ) for identification of bark beetles, and Ahmad Valizadeh ( Organization of Urban Sights and Landscape , District 18 of Tehran Municipality , Tehran, Iran) for helping in collecting some material. We are grateful to Dr AM Camerik (School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Republic of South Africa) for her criticism, remarks, and English language editing, which greatly improved the manuscript .