Dytiscus unistriatus Goeze, 1777 : 626

Fery, Hans, 2019, Nomenclatural notes on some taxa of Bidessus Sharp and designation of a neotype (Coleoptera: Dytiscidae: Hydroporinae: Bidessini), Zootaxa 4565 (4), pp. 579-589 : 582-583

Dytiscus unistriatus Goeze, 1777: 626

The text in Goeze's work is reproduced in Fig. 3. The word " Einstreife " may be a neologism by Goeze which is unknown to me, but its meaning is clearly " the beetle with one stria ". Goeze refers to Geoffroy and simply reproduces his short Latin text. Neither an additional description nor a locality is given.

It is noteworthy that Goeze (l.c. p. 624) gives Dytiscus parvulus O.F. Müller as a different valid species (see Fig. 4). It is very likely that Goeze himself did not study specimens of most of the taxa mentioned in his work. He lists (at least in the insects part, pp. 605–627) taxa which he has found in works of Geoffroy, Fabricius, O.F. Müller etc. and gives for each taxon at least one reference (see also the "Vorrede" [= Preface] in Goeze 1777). Nevertheless, by this he made some names available which before were unavailable because they had not previously been described according to the rules of the ICZN (1999).

Since Goeze refers to Geoffroy's " le ditique à une seule strie " and gives no additional locality, the syntype series as well as the type locality ("Paris environs") of Geoffroy's and of Goeze's taxon are the same. Goeze's name is—like those of Geoffroy and O.F. Müller—a nomen dubium.

On the other hand, since it cannot be definitely excluded that Goeze had studied material of unistriatus , I searched intensively for his material. According to Evenhuis (1997: 320) some parts of Goeze's collection came to the University of Pavia (MSNUP) and "other specimens were purchased by Hunter and may now be in HMUG." Goeze (1792) gives a list of the objects of his collection. The insects are listed on pp. 71–73 and among them (p. 72) one vial with water beetle larvae in alcohol and another vial with water beetles (namely Dytiscus marginalis L.). Trolldenier (2013) has studied the collection of Goeze as it is preserved in the MSNUP, but he reports no vials with insects. Originally, 278 vials came to Pavia of which only 131 are still present in the museum. According to Trolldenier (l.c. p. 75) John Hunter's offer to acquire Goeze's collection came too late. Thus, it is likely that all parts of the collection came to Pavia, including the insects. Unfortunately, requests at the MSNUP and the HMUG for Goeze's type material were unsuccessful.