Scarabaeus simson Linnaeus, 1758

Hielkema, Auke J., 2017, Some corrections and remarks regarding the nomenclature of Neotropical Athyreini, Passalini, Phanaeini, Rutelini, Cyclocephalini, Dynastini and Oryctini (Coleoptera: Scarabaeoidea), Insecta Mundi 2017 (561), pp. 1-18 : 9-10

Invalidation of Scarabaeus simson Linnaeus, 1758 as a synonym of Megasoma actaeon ( Linnaeus, 1758) ( Scarabaeidae : Dynastinae: Dynastini)

Linnaeus (1758: 345) gives a short description of the new species Scarabaeus simson , referencing Sloane (1725: 205, pl. 237, fig. 4, 5) and Browne (1756: 428, pl. 43, fig. 6). In Linnaeus (1764: 5) the first description is expanded upon, and this is done again in Linnaeus (1767: 542), albeit with different wordings. It is important to notice that in both later publications, the exact same references are used as in 1758. In all three publications are allusions to the similarities of Sc. simson with Sc. actaeon , which in each publication is the preceding species.

At present, Strategus simson ( Linnaeus, 1758) is the valid name of a species of Oryctini endemic to Jamaica, the Caribbean island that is mentioned by Sloane (1725) and Browne (1756) as the source of their specimens. Publications using this name include Ratcliffe (1976: 141) and Endrödi (1976: 155).

Curiously, the name Sc. simson Linnaeus, 1758 (also cited as Sc. simson Linnaeus, 1764 or 1767 or Geotrupes simson Fabricius, 1801 ) also appears in various old and new publications as a junior synonym of Megasoma actaeon ( Linnaeus, 1758) (between 1847 and 1915 as Megalosoma actaeon ), a species belonging to the Dynastini and occurring exclusively on the mainland of South America and southern Central America. Publications mentioning this synonymy include Endrödi (1941: 69, 1977: 41), Voirin (1978: 4) and Lachaume (1985: 34).

Indeed, several authors working extensively with Dynastinae actually use the specific epithet simson (albeit with different assigned years of description) both as a synonym or valid name in Strategus and as a synonym in Megasoma (see Burmeister 1847: 136 vs. 274; Arrow 1937: 76 vs. 99; Blackwelder 1944: 257 vs. 259; Endrödi 1985: 611 vs. 637; Ratcliffe and Cave 2015: 209 vs. Ratcliffe 2003: 461), suggesting that older literature, though commonly cited, is rarely critically read. The oldest publication I have found which attributes both uses of the name unambiguously to Linnaeus is Arrow (1937).

To elucidate the dual use of this name, it is necessary to look at some of the older post-Linnean publications.

Drury (1770: 81, pl. 36: fig. 3, 4) refers to Linnaeus (1767), Sloane (1725) and Browne (1756) in his text regarding the drawings of his Jamaican specimens. Fabricius (1775: 7, 10) appears to be the first to create a rift by using the name Sc. simson for a species allied to Sc. actaeon (with reference to Linnaeus (1767)) as well as mentioning the name in the description of his new Sc. titanus (with references to Sloane (1725) and Drury (1770)). The rift is continued in Goeze (1777), where on page 6 Sc. simson is mentioned, and on page 59 Sc. titanus “der Drurysche simson .” Importantly, both entries use the references Sloane (1725) and Drury (1770) next to other references, even though Goeze mentions that Fabricius (1775) was probably right in dismissing these references for simson “close to actaeon .” Each of the treatments even links to the other one, demonstrating that this dual use of references is not done accidentally. Strangely enough, Goeze also appears to say that simson “synonym of titanus ” is larger than simson “close to actaeon .” The first after Fabricius (1775) to consider the simson “close to actaeon ” as a completely different species than the simson “synonym of titanus ” is Herbst (1785), who treats the former on page 251 and the latter on page 282. He explicitly states that he does not understand why Goeze (1777) uses the references to Sloane (1725) and Browne (1756) for both species, while Fabricius (1775) excludes them from his simson “close to actaeon ” treatment. It appears that Herbst lacked access to at least some of the relevant publications, for otherwise he would likely have noticed that both “species” were in fact based on the same material. I believe it was Herbst’s text that completed the split between the two uses of the name Sc. simson . Olivier (1789) appears to be the first author to depict an actual minor male of M. actaeon with the name Sc. simson (p. 13, pl. 15, fig. 142) while showing an actual St. simson under the name Sc. titanus (p. 26, pl. 5, fig. 38).

Hope (1837: 87) places Sc. titanus in his new genus Strategus . Burmeister (1847: 136) upholds this placement and Fabricius’ vision of Sc. simson as a synonym of St. titanus . Chapin (1932: 449) applies the principle of priority and makes Sc. titanus a synonym of St. simson instead of vice versa. All later authors also treat St. simson as a valid species and Sc. titanus as its synonym.

In conclusion, I restate that Sloane (1725) and Browne (1756), the references used by Linnaeus, both mention a species with a length of about 3 to 4 cm living on Jamaica. This applies to St. simson but not to M. actaeon , which has a minimum length of over 5 cm and is strictly continental. It is thus clear that Linnaeus’ description of Sc. simson concerns the Jamaican species Strategus simson . The other use of the name, as a synonym of Megasoma actaeon , is clearly erroneous and a relic of a time in which zoological taxonomy and nomenclature were less developed. From the texts in the various early taxonomic works it can be concluded that the superficial similarities between these species, especially the convergent characters of two forward-protruding thoracic horns, the recurved and bifurcate cephalic horn and the uniform blackish color, have been the source of the misapplications of the name Sc. simson and the eventual schism of this name. I consider Olivier’s (1789) application of the name Sc. simson for a minor male of the present M. actaeon as a misidentification. As is evident from the various recent publications using both present meanings of the name Sc. simson , the dual application of this name has not yet been rectified. I hereby therefore invalidate the use of the name Scarabaeus simson Linnaeus, 1758 (also 1764, 1767 and Geotrupes simson Fabricius, 1801 ) as a synonym of Megasoma actaeon ( Linnaeus, 1758) .