Gnathoncus cerberus Auzat, 1923

Penati, Fabio, 2009, An updated catalogue of the Histeridae (Coleoptera) of Sardinia, with faunistic, zoogeographical, ecological and conservation remarks *, Zootaxa 2318, pp. 197-280 : 235

40. Gnathoncus cerberus Auzat

Gnathoncus Cerberus [sic!] Auzat: Winkler 1925: 478

Literature data. “Sardinia” ( Winkler 1925; Mazur 1984; Audisio et al. 1995; Mazur 1997, 2004; Yélamos & Lackner 2004). Sassari prov.: Scala di Giocca, Grotta [= cave] dell’Inferno, entrance, on bat guano, AD ( Auzat 1923); Scala di Giocca, Grotta dell’Inferno ( Porta 1926; Luigioni 1929; Barajon 1966; Puddu & Pirodda 1974; Vienna 1980; Cassola 1982); idem, 14.IV.1902, AD, 122 syntypes (52 CAD, 10 CCM, 54 CGB, 2 CGM, 3 CPL, 1 CPV); idem, sd, AD, 1 syntypus (CUL).

Unpublished records. Sassari prov. : Scala di Giocca, Grotta del Diavolo [= Grotta dell’Inferno], 18.III.1966, 22 ex ( DPPS) .

Chorotype. To be defined: the species is known also from Grotta di [= cave of] Frasassi [= Grotta del Santuario della Beata Vergine] (Marches region, mainland Italy) ( Bertolani et al. 1994), Bulgaria ( Thomas & Secq 2000) and Serbia ( Lackner & Pavićević 2008).

Italian distribution. Marches and Sardinia.

Ecology. Always found on bat guano, where it probably feeds on Diptera larvae ( Lackner & Pavićević 2008).

Notes. In Penati and Vienna (2005, 2006a) the date of capture of the specimens preserved in the Lostia di Santa Sofia collection (CUL) is erroneously given as “1939” (see “Data collection”); in fact, the label does not include a collection date, but reads “Grotta dell’Inferno / Scala di Giocca / leg. Dodero”, which proves without a doubt that this is one of the numerous specimens collected in April 1902 by the well-known Genoan entomologist and which Lostia received as a gift.

In the most recent faunistic works on the Italian Histeridae ( Audisio et al. 1995; Penati & Vienna 2002, 2005, 2006a) the record by Bertolani et al. (1994) was disregarded as a precaution. This was motivated by the fact that the specimens, although identified by one of the above authors (P. Vienna), could not be compared with the type material and their identity was considered doubtful; additionally, until then the species had always been considered a Sardinian endemic and was known exclusively from Grotta dell’Inferno (cf. Vienna 1980; Mazur 1984, 1997; etc.). Later, the finding of specimens in a cave near Vraca in Bulgaria ( Thomas & Secq 2000), but most of all the confirmation of the correct identification of the specimens from the Marches after comparison with Sardinian ones and new catches, cleared all doubts about the presence of G. cerberus in mainland Italy, ignored also by Mazur (2004) and Yélamos and Lackner (2004). Lastly, the species was very recently recorded also from Serbia, which suggests that “ this species is spread over a much larger area, and that its apparent rarity owes to its secretive habits ” ( Lackner & Pavićević 2008).

I here provide the exact collecting data of the specimens from Grotta di Frasassi, all kept in the Vienna collection ( CPV): Literature data. Italia, Marche [= Marches], Ancona , Genga , Grotta del Santuario [= della Beata Vergine], [340 m], 7.IV.1988, G. Manicardi leg., 3 ex, P. Vienna det. ( Bertolani et al. 1994) . Unpublished records. Italia, Marche [= Marches], Ancona, Genga , Gola di Frasassi , Grotta [del Santuario] della Beata Vergine, [340 m], 8.I.2008, su guano [= on guano], G. Carotti leg., 2 ex, P. Vienna det ..

Finally, I consider it useful to add that the examination of the many specimens preserved in the collections of MSNG, of the pair from Bulgaria kindly sent to me for study by Michel Secq, and of the specimens from Frasassi (CPV), showed that very few specimens possess, on the pigidium, the famous “ ligne médiane […] lisse ” described by Auzat (1923) and which according to this author “ distingue à première vue Gn. cerberus des autres espèces du genre Gnathoncus ”. This feature, highlighted by all subsequent authors (e.g. Vienna 1980; Thomas & Secq 2000; Lackner & Pavićević 2008) and always used in the identification keys of the Palearctic species of the genus Gnathoncus Jacquelin du Val , is deceitful and often misleading considering that a smooth, median longitudinal band is sometimes more or less obvious in specimens of G. rotundatus (Kugelann) and G. nannetensis (Marseul) (Penati pers. obs.; Secq in litteris). On the contrary, the best character for distinguishing G. cerberus from all other species with smooth intervals between the punctuation at the tip of the elytra is, in my opinion, the particular sculpture of the pygidium, characterized by transversely elongate punctures, set far apart and lying on an almost completely smooth surface; these punctures are instead more marked and more tightly set in the other species.