The Zoology Museum of the University of Padova finds its roots in the 18th century natural history collections of Antonio Vallisneri (1661–1730), a professor of medicine. It became a proper Museum of Zoology in 1869 under the chair of Giovanni Canestrini (1835–1900), who made great efforts towards enlarging and cataloguing the entire zoological collections and providing the museum with an international profile.

Canestrini was one of the most eminent Italian zoologists of the 19^th century, known for his first translation of Charles Darwin's “On the origin of species” in 1864 and for his effort in spreading the evolutionary theory in Italy (Minelli & Casellato 2001). After the completion of his studies at the University of Vienna in 1861, he became a professor of Natural History at the University of Modena from 1862 to 1869, working as a zoologist and anthropologist and publishing the first catalogues of Italian spiders together with Pietro Pavesi (1844–1907) (Canestrini & Pavesi 1868, Canestrini & Pavesi 1870). In 1869, he became Professor of Zoology, Comparative Anatomy and Physiology at the University of Padova where he remained until his death. During this period he dedicated most of his works to arachnology, publishing the first consistent studies on this field in Italy together with his students, among whom emerged relevant personalities of Italian zoology, such as Filippo Fanzago (1852–1889) and Antonio Berlese (1863–1927) (Minelli 1998, Bagella & Pantaleoni 2011, Guariento et al. 2016a). In the last two decades of his life, Canestrini worked almost exclusively on mites and from 1885 to 1889 published eight volumes of the catalogue of Italian Acari entitled “Prospetto dell'acarofauna Italiana”, that was left unfinished, as well as several dozen of papers describing new species (Ragusa 2002). His work continued tirelessly until his death in Padova in 1900.

After Canestrini, the museum went through several periods of abandonment in the 20^th century, with a discontinuous management and curation which resulted in the loss of important parts of the collections. A temporary recovery of the collections was completed by Marcuzzi (1966) but the museum reopened to the public only in 2004 (Nicolosi 2016). In 2015, when our project started, Canestrini's arachnological collection was in a precarious status with its content being unknown, despite an attempt at revision in the 1980s.

Material and methods

First, a comprehensive collection database has been completed, registering locality information from data labels in the Darwin Core standard (Wieczorek et al. 2012). Each label provides the name of a taxon, the locality, the date (often the date of inventory in the collection) and an inventory number referring to the original catalogues compiled by Canestrini. These catalogues, deposited in the Museum and described by Minelli & Pasqual (1982), are divided in: “Aracnidi e Miriapodi”, registering specimens of Araneae, Opiliones, Pseudoscorpiones, Scorpiones and Solifugae from 1870 to 1889 (1035 records); “Catalogo degli acari conservati in alcool” registering mites preserved in ethanol from 1874 to 1898 (865 records); “Acari preparad microscopici” registering microscope slides from 1876 to 1888 (1078 records). Each catalogue mostly provides the same information as on the data labels, in addition to eventual notes on the collectors or regarding the exchanges of specimens with different arachnologists (e.g. T. Thorell, L. Koch). Both catalogues and data labels have been digitized and the database integrates the data obtained from both sources. Furthermore, an extensive search for historical documents (notebooks, correspondence, as well as Canestrini's scientific output) was performed in order to add additional information on the collections. Moreover, during the curatorial restoration, each glass tube was replaced with a new one and filled with 75% ethanol, while microscope slides are kept in the original folders.

The taxonomic revision of the collection is now under way involving three of us: Paolo Pantini (Araneae), Giulio Gardini (Pseudoscorpiones) and Luis A. Guariento (Scorpiones, Solifugae). Other arachnologists revised part of the collection in the past: Valle (1955) worked on the acaroteca preserved in ethanol, Brignoli (1983) on the spiders described by Canestrini, Hansen (1986) on spiders of the family Salticidae, and Chemini (1986) on Opiliones. The whole acaroteca needs extensive revision, and awaits an availability of acarologists.

Results

The results concerning each arachnid order are presented below. From a curatorial perspective, the overall conservation status of the collection was precarious since several tubes were found partially or completely dried, especially in the case of pseudoscorpions, and several microscope slides present a rather deteriorated mounting medium. Parts of the collection were returned by Italian museums where they were on loan since the last century, in particular the entire collection of harvestmen (Trento Museum of Science — MUSE) and some folders of microscope slides belonging to the acaroteca (Bergamo Museum of Natural Sciences). Concerning the search for historical documents, three notebooks have been recovered in the library of the Trento Museum of Science: i) “Studi sugli acari italiani di G. Canestrini e F. Fanzago e sul genere Dermaleichus (ed affini) di G. Canestrini, 1876 a 1878, studi fatti a Doss Tavon, Padova e Santa Maria di Cervarese”; ii) “Note di Giovanni Canestrini 1881, 1882, 1883” that deals with mites of the genus Gamasus and pseudoscorpions; iii) “Raccolta di acari parassiti degli insetti di Riccardo Canestrini, incominciata a Dos Tavon (Trentino) il 15 Agosto 1880”. Moreover, from the same library about a hundred letters were recovered, some of which contained the signatures of T. Thorell and L. Koch. The study and translation of these documents could provide interesting information regarding the collection and the taxonomic research conducted by Canestrini.

Araneae

The spider collection contains specimens that mainly originated from Italy and, to a lesser extent, from European (i.e., Croatia, England, Finland, France, Germany, Spain, Sweden) and extra-European (i.e., Algeria, Argentina, Eritrea, Turkey, United States) countries. The foreign material often came from exchanges between Canestrini and renowned European arachnologists, as in the case of the collection from Germany (89 specimens from Nuremberg sent by L. Koch) and from Sweden (67 specimens sent by T. Thorell). According to the historical catalogue, the first spider material was registered in 1870; the last material was registered in 1887. The collection was in part revised by Brignoli (1983), who considered the species described by Canestrini. However, it seems that Brignoli (1983) did not see all the specimens in the collection, since the part of Canestrini's type material rediscovered by us was not mentioned in his revision. All but a few specimens of Salticidae were revised by Hansen (1986).

We found 28 out of the 41 species described by Canestrini (solely or in collaboration with Pavesi): they are presented in Tab. 1 following the nomenclature of World Spider Catalog (2018). In nine cases, the material surely represents types, while other eight specimens are recorded as “probable types” because they were not labelled as such and their collection data are too generic. Precisely, most of these probable types belong to the species described before the arrival of Canestrini to Padova in 1869 (Canestrini 1868a, 1868b; Canestrini & Pavesi, 1868) and they are simply indicated in the catalogue as registered “at the end of 1870”, while the collection dates are not reported. Among the material, there are also three preserved species considered inquirendae by Brignoli (1983), for which further examination would clarify their taxonomic status: Melanophora kochi Canestrini, 1868, Prosthesima prognata Canestrini, 1876 and Linyphia furcigera Canestrini, 1873.

In the collection, type specimens of the species described by Thorell based on the material collected by Canestrini in Italy are preserved (Thorell 1872, 1875): Drassus tenellus Thorell, 1875, Drassus spinulosus Thorell, 1875, Epeira limans Thorell, 1875, Erigone nigrimana Thorell, 1875, Gnaphosa plebeja Thorell, 1875, Erigone hilaris Thorell, 1875, Linyphia arida Thorell, 1875, Erigone phaulobia Thorell, 1875, Lycosa nebulosa Thorell, 1875, Sagana rutilans Thorell, 1875, Theridion histrionicum Thorell, 1875, Xysticus kempeleni Thorell, 1872 and Xysticus ninni Thorell, 1872. An examination of these specimens should confirm/clarify their status as well.

Pseudoscorpiones

This collection includes specimens from Italy, and three tubes from Paraguay sent to Canestrini by his pupil Luigi Balzan (1865–1893) in 1889. Balzan became a specialist on pseudoscorpions under the supervision of Canestrini and conducted pioneering research on these arachnids in South America (Balzan 1890, 1892; Guariento et al. 2016b). His studies led to the description of 27 new species from Paraguay, many of which are still valid (Mahnert 2016). According to the historical catalogue, the first pseudoscorpion material was registered in 1873; the last material was registered in 1889.

As for spiders and harvestmen, Canestrini published the first consistent works on these arachnids in Italy (Canestrini 1875a, 1875b, 1876), presenting the state-of-the-art in the encyclopedic monograph “Acari, Myriapoda et Scorpiones hucusque in Italia reperta” edited by Berlese (Canestrini 1883, 1884, 1885). Of the six species he described, we found only four. All are represented by putative syntypes which we have examined confirming the current interpretation of these species (Tab. 2). The syntype of the valid species Neobisium (= Obisium) dolicodactylum (Canestrini, 1874) was examined by Callaini (1985), but it was absent from the collection during the cataloguing work. The three specimens collected by Balzan in Paraguay comprise Gomphochernes (= Chernes) communis (Balzan, 1888) (Chernetidae), Paratemnoides (= Chernes) nidificator (Balzan, 1888) (Atemnidae) and Chernes capreolus Balzan, 1888 = Lustrochernes argentinus (Thorell, 1877) (Chernetidae), all of which seem to appertain to the original type series.

Tab. 1:

Species of the order Araneae described by Canestrini, with their current status in the collection (present in/absent from the collection and/ or the historical catalogue; types/not types)

Tab. 2:

Species of the order Pseudoscorpiones described by Canestrini, with their current status in the collection (present in/absent from collection and/or the historical catalogue; types/not types)

Scorpiones and Solifugae

The scorpions, collected almost exclusively from Italy, partly constituted the basis for the monograph on Italian scorpions published by Fanzago (1872), since several localities in the publication match those given in the catalogue. In fact, Canestrini never dedicated himself to scorpions, as demonstrated by the few specimens preserved in his collection, and left them to his pupil Fanzago who generalized the knowledge on these arachnids in Italy (Canestrini 1875b). In the collection, five specimens of Euscorpius (= Scorpius) canestrinii (Fanzago 1872) (Euscorpiidae) are preserved that almost certainly appertain to the original type series. Vachon (1978) described two specimens of this species belonging to the “Collection Canestrini” and deposited at the Hungarian Natural History Museum (Budapest), consequently designated by Kovarik (1997) as a lectotype and paralectotype. It is likely that these specimens were donated to the Museum in Budapest by Canestrini from the same syntype series currently deposited in Padova.

The collection also contains a single solifuge from Egypt, a Rhagodidae, Pocock, 1897, identified by Canestrini as Solpuga melanus Savigny. This specimen has not yet been re-examined.

Opiliones

The harvestmen collection was revised by Chemini (1986) and includes specimens from Italy and France, the latter collected by Eugène Simon. According to the historical catalogue, the first harvestmen material was registered in 1870; the last material was registered in 1875. In his pioneer works on harvestmen (Canestrini 1871, 1872a, 1872b, 1872c, 1873, 1874, 1875a, 1875b, 1876, 1888), Canestrini described 17 species from Italy and South America, most of which are represented by type series in the collection (Tab. 3).

Tab. 3:

Species of the order Opiliones described by Canestrini, with their current status in the collection (present in/absent from collection and/or the historical catalogue; types/not types)

Acari

The Canestrini Acaroteca consists of 438 microscope slides, most of which originated from Italy (especially from Veneto and Trentino) and to a lesser extent from Europe (i.e. France, Germany, Hungary and Sweden) and extra-European countries (i.e. Brazil, Eritrea). In several cases, the host from which the specimens were collected is also indicated (e.g. domestic and wild animals, humans, foods or plants). Along with the acaroteca, the acarological collection also includes 115 samples in ethanol and glycerine, which were partly reviewed by Valle (1955) and therefore not examined during our curatorial revision. A number of Canestrini's students contributed to the acaroteca, among them the renowned Italian entomologist Antonio Berlese (slides of “Collezione Berlese”), who continued Canestrini researches and became a leading world scientist in the field of acarology (Ragusa 2002), as well as other personalities such as Canestrini's brother Riccardo Canestrini (1859–1891) and Enrico Sicher (1865–1915); both published several works on mites in cooperation with Canestrini or alone. Conversely, no slide reports the name of Filippo Fanzago, with whom Canestrini started his acarological studies (Canestrini & Fanzago 1876a, 1876b, 1877). Moreover, only a single slide received from a foreign acarologist is available in the collection: the slide from French Édouard Louis Trouessart (1842–1927) with whom Canestrini published a joint note (Trouessart & Canestrini 1895).

Of the over 140 species of Acari described by Canestrini, many are represented in the acaroteca by probable type series. Among them, two slides are labelled as holotypes by an anonymous, recent author (the holotypes of Rhagidia gigas Canestrini, 1886 and Coccorhagidia clavifrons Canestrini, 1886). The taxonomic review of this prestigious acarological collection is required to evaluate and to clarify the identity of numerous species.