Neottialges (Caloenectes) vulturis (Dubinin, 1956) (Acari: Hypoderatidae) from the Eurasian griffon vulture (Gyps fulvus) in Italy: first record in Europe, redescription and pathological changes in the host

Deutonymphs of the astigmatan mite Neottialges (Caloenectes) vulturis (Dubinin, 1956) comb. n. (Astigmata: Hypoderatidae) were found during the anatomo-histopathological study of a Eurasian griffon vulture, Gyps fulvus, found dead in Central Italy. After skinning, numerous cystic formations were visible in the subcutaneous tissue of the vulture, each containing a parasitic mite. Microscopically, subcutaneous tissue showed large areas of severe granulomatous inflammation. To our knowledge, this is the first record of this poorly known hypoderatid mite in Europe, about five thousand kilometers west from the type locality in Kirghizstan. The deutonymphal stage of N. (C.) vulturis is redescribed following modern standards of taxonomic description for astigmatan mites. This mite, previously unassigned to a subgenus, is now placed in the subgenus Caloenectes Fain, 1966.


Introduction
Mites of the family Hypoderatidae are mainly associated with birds and rarely occur in rodents. At the deutonymphal stage (also named hypopus in Astigmata), these mites are subcutaneous or visceral tissue parasites, whereas the other life stages (larva, protonymph, tritonymph and imago) are commensals inhabiting the nests of corresponding vertebrate hosts (Fain 1967;Fain and Bafort 1967;OConnor 1982 and1985;Wurst and Havelka 1997;Krantz and Walter 2009). An unusual way of feeding by hypopi in the host tissues using a modified genital papillae was recently revealed by Alberti and co-authors (2016) with an example in Neottialges evansi Fain, 1966 parasitizing cormorants. This family currently includes over 80 species in 21 genera. The greatest majority of hypoderatid species are known only from deutonymphs, while adults and tritonymphs are described for only 20 species (Mironov and Kivganov 2010;Mironov and OConnor 2013). Neottialges vulturis (Dubinin, 1956) was incompletely described by Dubinin (1956) from two vulture species, Gyps fulvus (Hablizl) (type host) and Gyps himalayensis Hume (Accipitriformes: Accipitridae), from Asian republics of the former USSR. Since that time, the mite has never been recollected. In the present work, we provide a modern redescription of the congested deutonymph of this species and describe pathological changes provoked by the presence of numerous mites in the subcutaneous tissues of a Eurasian griffon vulture, G. fulvus, found dead in Central Italy.
The Eurasian griffon vulture is a protected species in Italy and inhabits 5 distinct areas from the eastern Alps to the southern Apennines, Sardinia and Sicily. These populations mainly originate from reintroduction and restocking efforts, and, due to persistently high human-induced mortality and a low number of breeding individuals, the species is regarded as critically endangered at a national scale (Rondinini et al. 2013). Although the griffon vulture was once likely widespread throughout peninsular Italy, the last account of its occurrence along the central Apennines (specifically dealing with the Marche region) dates back to the XVI century (Pandolfi and Zanazzo 1993), after which time it became extinct. Between 1994 and2002, 93 vultures from Spain were re-introduced in the central Apennines (Monte Velino reserve, Abruzzo region), where they successfully settled (Potena et al. 2009), establishing five reproductive colonies, from 1997 to 2012 . At present, up to 45 nesting pairs are estimated, and resident adults range across ca. 7,000 km 2 (Altea et al. 2013).

Materials and methods
Case report. On the 6 th of March 2015, an adult Eurasian griffon vulture was found dead in the Borgorose Municipality, Rieti Province, Lazio Region, Central Italy. The bird, discovered by local people, was recovered by the Forest Service near a paved road at the base of a concrete pole (supporting a power line) the day after a severe windstorm occurred in the area. From the data reported on the ring, it was possible to ascertain that the individual was born in Spain in 2008. It had been recovered in bad condition in Saldaña municipality (Spain), where it was ringed (metal and yellow-coloured ring, code CV8) and released from the Burgos rehabilitation centre on December 19 th 2008. This vulture was photographed for the first time in Italy on December 2011, at the Monte Velino Reserve feeding point (Forest Service, unpublished data). It was then re-sighted several times in this area in December 2011 and January 2012. Subsequently, it was no longer recorded until March 2013, whereupon it became a regular monthly visitor at the feeding point, until December 2014. During management and research activities carried out by the Forest Service, it was captured on July 28 th 2014. At this time, it weighed 8.05 kg and was sexed as a male by molecular markers from plucked feathers (Garofalo et al. 2016).
Anatomo-histopathological study. At necropsy the vulture weighed 9.4 kg and appeared in good health status. It was possible to ascertain that the bird was dead as a result of an impact. Large haematomas were detected in subcutis and muscles of neck, head and chest and haemorrhagic effusions were present in splanchnic cavity between the heart and lungs. At skinning, the subcutaneous tissue was diffusely thickened and grainy in appearance. Very numerous whitish, translucid, 0.5-1 mm nodules, covered almost the whole surface of subcutis and, to a lesser extent, the superficial muscles of chest, back and legs. For histological examinations, samples of subcutis were fixed in 10% buffered formalin, embedded in paraffin, cut at 5 μm and then stained with hematoxylin and eosin.
Microscopically, the subcutaneous tissue showed large areas of severe granulomatous inflammation, with many macrophages with a foamy appearance due to the phagocytosis of lipidic debris, probably of parasitic origin, and, to a lesser extent, multinucleated giant cells. Numerous cystic formations (Fig.1a), each containing a parasitic mite, were seen (Fig.1b). Foci of lymphocytes and plasma cells were occasionally observed, sometimes surrounding parasitic debris. A similar pathological picture was previously described by Schwan and Sileo (1978) in a Phalacrocorax carbo (Linnaeus) parasitized by the mite Neottialges evansi Fain 1966. By gently crushing some of the cysts with a needle under the stereo-microscope, it was possible to isolate the mites.
Taxonomic study. The redescription and measurement techniques are given according to the modern standard used for hypoderatid mites (Wurst and Havelka 1997;Mironov and Kivganov 2010;Mironov and OConnor 2013). The general terms follow OConnor (1985), the idiosomal chaetotaxy follows Griffiths et al. (1990) and the leg chaetotaxy is that of Grandjean (1939) and Griffiths (1964). All measurements are in micrometers (μm). The material used for taxonomic study is deposited in the Zoological institute of the Russian Academy of Sciences (Saint Petersburg, Russia).

Systematics
Family Hypoderatidae Murray, 1877 Genus Neottialges Fain, 1966 The genus Neottialges was established by Fain (1966) and originally included six species; at present it incorporates 28 species and is the most specious within the family (Mironov and Kivganov 2010). Within this genus, Fain (1966Fain ( , 1967 originally recognized three subgenera, Caloenectes Fain, 1966, Neottialges s str., and Pelecanectes Fain, 1966. Further, Fain and Lukoschus (1986 established two more subgenera, Ardeidectes Lukoschus, 1986 andHeronidectes Fain andLukoschus, 1986. Representatives of this genus are presently known from birds of the orders Accipitriformes, Ciconiformes, Charadriiformes, Columbiformes, Musophagiformes, Falconiformes and Pelecaniformes (Fain 1967;Fain and Lukoschus 1986;Mironov and Kivganov 2010). In the world revision of hypoderatids parasitizing birds, Fain (1967) did not assign Neottialges vulturis to any subgenus, because he was unable to re-examine any specimens of this mite. Based on the recollected material we examined in the present study, we place this species in the subgenus Caloenectes (see remark below).
Remarks -Dubinin (1956) described this hypoderatid species from a deutonymph, thinking it was part of the feather mite genus Gabucinina Oudemans, 1905 (Gabuciniidae), since he erroneously suggested that feather mites (Astigmata: Analgoidea and Pterolichoidea) can have a deutonymph in their life cycle. In the world revision of hypoderatids, Fain (1967) provisionally placed this mite species in the genus Neottialges Fain, 1966, because he had no specimens to examine. In the present paper, we confirm this mite belongs to the genus Neottialges and place it in the subgenus Caloenectes Fain, 1966 based on the following subgeneric characteristics observed in this species: the cuticle of the entire idiosoma is strongly and monotonously sclerotized and dorsomedian setae d1, e1 and h1 are very short. Among the seven previously known species of this subgenus (Fain 1966(Fain , 1967(Fain and 1973Pence 1973;Fain and Lawrence 1986) It is necessary to note that Fain (1984) Fain, 1984 with the type species, Gypsodectes verrucosus Fain, 1984, described from a single female found in the nest of Gyps coprotheres (Forster JR) in South Africa. Based on this finding, he suggested that Neottialges vulturis, known only from deutonymphs, also belongs to the genus Gypsodectes. However, he did not have any real proof, such as pharate specimens (deutonymph in exuvium of protonymph or tritonymph in exuvium of deutonymph), to show that N. vulturis hypopi correspond to adult mites of the genus Gypsodectes. Deutonymphs in Astigmata are so morphologically different from all other stages of hypoderatids that it is practically impossible to guess their correspondence without pharate specimens, even when hypopi and other stages are found in the same nest. Indeed, there are a number of examples where birds simultaneously house several different hypoderatid species, usually belonging to different genera (Fain 1967;Fain and Lukoschus 1986;Mironov and Kivganov 2010;Mironov and OConnor 2013). Therefore, we retain the hypoderatid mite considered herein in the genus Neottialges.

Discussion
This is the first report of N. vulturis after its original description over 60 years ago (Dubinin 1956). Interestingly, this report is located about five thousand kilometers west of the type locality in Kirghizstan and for the first time in Europe. The examined vulture was born in Spain and quite possibly it arrived in Central Italy already infested, as the primary portion of hypoderatid deutonymph infections usually comes from parents via the nest, where the remaining part of life cycle of these mites takes place, and where the next generation of deutonymphs appears. Therefore, the actual distribution of N. vulturis should likely be extended two thousand kilometers westward. The geographic distribution of this mite could overlap completely with that of the Eurasian griffon vulture, extending from Portugal, Morocco and Algeria in the west to Asian republics of the former USSR and India in the east, and from Yemen and Ethiopia in the south to Kazakhstan in the north. It could even cover the range of the whole genus Gyps, extending across areas of Europe, Asia and Africa, since it was also recorded from Gyps himalayensis.
Notwithstanding this theoretically large geographical distribution, these mites can be considered as neglected parasites. Probably because of nature of the host and the seemly low pathological effect they elicit, there are few reports and data quantifying the pathological impact of these mites on their hosts. In the present case, the number of encysted mites, involving both subcutaneous and muscular tissues, was very high, in the order of thousands, and a marked inflammatory reaction was detectable. It is difficult to ascertain if this pathological picture had some effect on host fitness and survival, but a reduced functionality of the skin and animal suffering cannot be ruled out, despite of the apparent good health status revealed at necropsy. Nevertheless, Schwan and Sileo (1978) described similar pathological findings in a Phalacrocorax carbo parasitized by Neottialges evansi deutonymphs, reporting no apparent clinical discomfort in the bird.