Omorgus (Omorgus) suberosus ( Fabricius, 1775 )

da Costa-Silva, Vinícius, Strümpher, Werner P., Barclay, Maxwell V. L. & Vaz-de-Mello, Fernando Z., 2024, An illustrated catalogue of South American species of Omorgus Erichson, 1847 (Coleoptera, Trogidae, Omorginae) including a neotype designation and taxonomical changes, Contributions to Entomology 74 (1), pp. 81-101 : 81-101

Omorgus (Omorgus) suberosus ( Fabricius, 1775)

Fig. 7

Trox suberosus Fabricius, 1775: 31 (original description); Fabricius 1781: 34 (diagnosis); Fabricius 1787: 18 (diagnosis); Olivier 1789: 6 (diagnosis); Gmelin 1790: 1586 (diagnosis); Herbst 1790: 29 (description); Fabricius 1792: 87 (diagnosis); Fabricius 1801: 111 (diagnosis); Illiger 1802: 332 (catalogue); Schönherr 1806: 118 (catalogue); Castelnau 1840: 107 (as ‘ tuberosus ’ – misspelling); Sturm 1843: 112 (checklist); Blanchard 1847: 190 (catalogue); Lacordaire 1856: 151 (type designation of Omorgus) Harold 1869: 1090 (checklist); Harold 1872: 119 (redescription); Horn 1874: 5 (diagnosis, comments); Burmeister 1876: 257 (diagnosis); Berg 1881: 99 (checklist); Arrow 1903: 516 (notes about fauna of the St. Vincent Island); Bruch 1911: 194 (checklist); Leng 1920: 253 (catalogue); Mutchler 1925: 238 (catalogue of Galapagos Islands); Blatchley 1928: 64 (records for Florida); Leng 1928: 422 (catalogue of New York); Sim 1934: 11 (larvae description); Denier 1936: 205 (natural history); Hayward 1936: 217 (feeding habit); Blackwelder 1944: 219 (catalogue – as ‘ suberosa ’); Van Dyke 1953: 123 (distribution data); Haaf 1954: 739 (catalogue of Australia); Vaurie 1955: 60 (redescription); Howden and Vaurie 1957: 4 (pronotum and aedeagus drawing); Ritcher 1958: 325 (biology); Vaurie 1962: 144 (redescription); Landin 1963: 4 (record from Cape Verde Is.); Zimsen 1964: 38 (catalogue); Ritcher 1966: 73 (biology); Hatch 1971: 464 (key to the Pacific Northwest beetles); Chalumeau and Gruner 1974: 787 (catalogue of French Antilles); Paulian 1981: 4 (larvae morphology); Young and Hamm 1985: 93 (feeding experiment); Young 2006: 271 (biology); Bouchard et al. 2024: 372 (mentioned as type species).

Trox (Omorgus) suberosus : Burmeister 1876: 257 (redescription); Arrow 1912: 62 (catalogue); Scholtz 1982: 13 (systematics).

Omorgus suberosus : Erichson 1847: 111 (new combination); Baker 1968: 42 (larvae’s description); Chalumeau 1977: 231 (corrigenda); Scholtz 1986 a: 361 (phylogenetics); Scholtz 1986 b: 54 (distribution from Australia); Scholtz 1990: 1407 (redescription); Ratcliffe 1991: 157 (redescription); Baraud 1992: 24 (diagnosis); Browne et al. 1993: 199 (phylogeny); Muñoz-Batet and Lopez-Colon 1995: 279 (record from Czech Republic); Páramo 1997: 29–31 (distribution); Costa et al. 1988: 109 (larvae description and illustration); Deloya 2000: 69 (checklist); Ratcliffe 2002: 8 (checklist from Panama); Rosano-Hernandes and Deloya 2002: 32: (natural history); Morón 2003: 408 (checklist); Deloya 2003: 132 (diagnosis and distribution); Diéguez and Gómez 2004: 94 (checklist); Deloya 2005: 122 (checklist); Nikolajev 2005: 322 (larvae characteristics); Löbl and Smetana 2006: 79 (catalogue); Lopes et al. 2007: Mora-Aguilar and Montes de Oca 2009: 575 (distribution); Philips 2009: 4 (association with mites); Krell 2010: 4 (checklist); Carvajal et al. 2011: 161 (checklist); Zidek 2013: 17 (checklist); Verdugo 2014: 212 (mention); Ratcliffe 2015: 189 (checklist from Peru); Ziani et al. 2015: 3 (distribution); Baena et al. 2015: 2, 4 (feeding behaviour); Pittino and Bezdĕk 2016: 54 (checklist); Strümpher et al. 2016: 57 (phylogeny); Zidek 2017: 109 (checklist); Smith 2017: 87 (notes, distribution); Cortez et al. 2017: 4 (natural history); Huchet and Costa-Silva 2018: 565 (new distribution records from South America); Hielkema and Hielkema 2019 (checklist of the Guianas); Miquel 2019: 184, 186 (distribution); Giraldo-Mendoza 2021: 64 (checklist from Peru); Costa-Silva et al. 2021: 2008 (review of Brazilian species).

Omorgus (Omorgus) suberosus : Gianizella and Prado 1999: 749–751 (in poultry houses); Lopes et al. 2007: 29–31 (in poultry houses); Strümpher and Kalawate 2023: 518 (catalogue of the Oriental and Palearctic species); Pablo-Cea et al. 2023: 16 (catalogue of El Salvador).

Synonyms.

For a comprehensive list, see Pittino and Bezdĕk (2016: 54–55) and Smith (2017: 88).

Type specimen examined.

Neotype, here designated (♂ NHMUK – Fig. 7 ). First label [white, printed]: “ BRASIL: Rio de Janeiro, / Cabo Frio, I- 1991, / F. Z. Vaz-de-Mello ”. Second label [red, Vinicius Costa-Silva’s handwriting]: “ NEOTYPE / Trox suberosus / Fabricius, 1775 / des. V. Costa-Silva, 2022 ”. Third label [white with black border, Vinicius Costa-Silva’s handwriting]: “ Omorgus / suberosus / Det. V. Costa-Silva, 2022 ”. Fourth label [white, printed]: “ [QR Code] / WORLD / TROGIDAE / DATABASE / WTD 0000386 ” (Fig. 7 E ). Type locality: “ Brasil, Rio de Janeiro, Cabo Frio ”.

Geographic distribution.

Widespread (see below). For details of distribution, see Huchet and Costa-Silva (2018) and Costa-Silva et al. (2021).

Neotype designation of Trox suberosus Fabricius, 1775 . Trox suberosus was originally described in 1775 by the Danish entomologist Johan Christian Fabricius (1745–1808) based on an unspecified number of specimens collected from “ Brasilia ” (Latin spelling meaning Brazil) that he had examined in the collection of Sir Joseph Banks (“ Mus. Dom. Banks ”). The collection is housed currently in The Natural History Museum, London, UK ( Fabricius 1775; Zimsen 1964). Seventy years later, Erichson (1847) described the genus Omorgus , transferring Trox suberosus to the new genus. Even after the proposal of Erichson (1847) and the subsequent designation of Omorgus suberosus as type species of the genus Omorgus by Lacordaire (1856), the species was historically cited as in its original combination by several authors (i. e., Harold 1869; Harold 1872; Burmeister 1876; Arrow 1903; Bruch 1911; Arrow 1912; Leng 1920; Mutchler 1925; Leng 1928; Denier 1936; Hayward 1936; Blackwelder 1944; Van Dyke 1953; Haaf 1954; Vaurie 1955; Ritcher 1958; Vaurie 1962; Zimsen 1964; Ritcher 1966; Hatch 1971; Chalumeau and Gruner 1974; Scholtz 1982). The species remained in the original combination until the systematic study carried out by Scholtz (1986 a), where the author proposed Omorgus as a genus based on several synapomorphies (see Scholtz 1986 a for more details). Scholtz’s proposal (1986 a), which was adopted by recent authors, was supported by the molecular phylogeny conducted by Strümpher et al. (2014).

Omorgus suberosus is native to the New World and is widely distributed throughout South, Central and North America (from Canada to southern Argentina) ( Vaurie 1962; Scholtz 1990; Huchet and Costa-Silva 2018; Costa-Silva et al. 2021). In South America Omorgus suberosus is present in all countries except Chile (see Diéguez 2008). It has also been recorded from the Galapagos Archipelago ( Ecuador) ( Vaurie 1962; Scholtz 1990).

The ubiquitous New World species has also been recorded from other parts of the world (outside of the New World) such as: Australia, Europe (from Belgium, Czech Republic, Spain), North Africa (from Morocco), Southeast Asia (from the Philippines), and on oceanic islands in the Pacific ( Fiji, New Caledonia) and Atlantic ( Cape Verde, Canary Islands) ( Vaurie 1955, 1962; Scholtz 1986 b; Scholtz 1990; Batet and López-Colón 1995; Páramo 1997; Ziani et al. 2015; Pittino and Bezdĕk 2016; Huchet and Costa-Silva 2018; Costa-Silva et al. 2021). The human hand may have contributed to the dispersal of Omorgus suberosus to almost all continents through human migrations, and international transport of products mainly via shipping. Harold (1872) mentioned specimens of Trox suberosus found in a wool shipment imported from Argentina in a factory in Verviers ( Belgium). With the fast and silent widespread introductions, plus the high degree of intraspecific variability (i. e., colour, size, the shape of elytral tubercles; see Harold 1872) of T. suberosus (originally described from Brazil), a lot of new species names were described for several countries / continents when in fact, they are just morphotypes of the introduced T. suberosus . For the list of synonyms, see Smith (2017) and Zidek (2017).

Omorgus suberosus is also known to be highly opportunistic, and in the absence of carcasses will exploit virtually any other source of keratin (or chitin) present in their environment. This species has been recorded feeding on eggs, dung and chicken feathers in poultry farms in Brazil ( Gianizella and Prado 1999; Lopes et al. 2007), locust eggs in Argentina (Baker 1986), as a “ potential predator ” of the eggs of the turtles in Mexico, Costa Rica and the Galapagos Islands ( Rosano-Hernández and Deloya 2002; Baena et al. 2015), and iguana eggs also in Galapagos ( Allgower 1979; Rosano-Hernández and Deloya 2002), being considered a risk factor for the survival of these (and other) species considered as vulnerable according to the International Union for the Conservation of Nature ( IUCN) (see Baena et al. 2015).

On the compilation of Fabricius types, Zimsen (1964) presented a list mentioning two type specimens of Trox suberosus : one from Joseph Banks’ collection (housed in the British Museum of Natural History - NHMUK) and another from the Zoologisches Museum, Kiel University ( ZMUK). Both specimens were meticulously studied by us; however, as first noted by Vaurie (1962), the type specimen of Trox suberosus lodged in Banks’ collection ( NHMUK) corresponds to Trox monachus (now Omorgus monachus – Fig. 8 ) described by Johann Friedrich Wilhelm Herbst in 1790, 15 years after Trox suberosus description. In the description, Fabricius (1775) mentioned “ elytris striatis ” and later “ Elytra minus rugosa […] ”, but none of these statements correspond to the specimen standing as “ type ” of Trox suberosus in Banks’ collection. This statement / description of “ elytris striatis ” was repeated in all of Fabricius’ subsequent publications that mentioned T. suberosus ( Fabricius 1781, 1787, 1792 and 1801; Fig. 9 ). According to Harold (1872), Trox monachus presents “ tuberculata elytrorum omnia, etiam suturalia, rotundam omnino tomentosa ” and Vaurie (1962) presents records of this species only from the USA (Florida, Nebraska, Kansas, Oklahoma and Texas); the type of Trox suberosus is from Brazil, probably Rio de Janeiro (see Papavero 1971). The other specimen mentioned by Zimsen (1964), from ZMUK (Fig. 10 ), was studied through detailed photographs kindly provided to us by Dr. Michael Kuhlmann ( ZMUK). With these high-resolution images from various angles, it was possible to confirm, without any doubt, that the specimen from ZMUK mentioned as a Trox suberosus ’ syntype by Zimsen (1964) is a specimen that belongs to the modern concept of the genus Trox , and not Omorgus . The identification to species level was not conclusive. However, considering that the species described by Fabricius comes from the Banks Collection, there is no reason (or evidence) to consider the specimen housed in ZMUK as part of the type series. The label with Fabricius’ handwriting saying “ suberosus ” on the specimen from ZMUK was probably put on later and corresponds to either a misidentification of the species or an inadvertent misspelling (between “ sabulosus ” and “ suberosus ”) of a specimen from his own collection.

Since Vaurie (1962), the name-bearing type specimen of Trox suberosus (mainly that from NHMUK) has been cited as “ problematic ” (i. e., Vaurie 1962; Hielkema and Hielkema 2019; Costa-Silva et al. 2021), because the specimen does not correspond to the original description. In the case here presented, we believe that all specimens widely recognized and identified as Trox suberosus were based on “ common sense ” and on a universally recognized concept, but not based on a proper name-bearing type. As presented here and well-documented in the literature (see Vaurie 1955), both Omorgus suberosus and O. monachus are morphologically well-defined, and universally recognized as different species, and should be treated as such. Due to its non-compliance with the description and the stated type locality, we here propose that the specimen housed in the Banks collection under the name suberosus Fabricius is a specimen of the North American Trox monachus which has been mistakenly substituted with the original material of Trox suberosus from Brazil, and that the original type material of Trox suberosus has been lost. Such a substitution is particularly credible in the Joseph Banks collection, since the specimens do not have locality labels or determination labels, and the handwritten name labels, and labels indicating ‘ type’, are pinned onto the drawers and not attached to the specimens. Hence a misplaced specimen would not be easy to recognize as such except by comparison with the original description.

In order to establish the single name-bearing type specimen of the widespread Trox suberosus , we propose the designation of a neotype. Our proposed neotype specimen (Fig. 7 ) morphologically match with the original description provided by Fabricius (1775; Fig. 9 A ) and fulfils the qualifying conditions of ICZN Article 75.3 ( ICZN 1999). To avoid possible future confusion and to maintain the type locality as consistent as possible, and to comply with ICZN Article 75.3. 6, we here select as the neotype a specimen from a similar locality as the presumed lost specimen collected by Joseph Banks during his voyage across the globe on the Endeavour (1768‒1771) ( Zimsen 1964; Papavero 1971). According to Papavero (1971), “ Brasilia, Dom. Banks of Fabricius ” refers to the collection made by Sir. Joseph Banks in Ilha Rasa, off the coast near the Guanabara Bay (Rio de Janeiro) on December 7 th, 1768 (for details, see Banks 1896; also see Cupello et al. 2023 for additional information about Joseph Bank collection). For detailed diagnoses and redescriptions of Omorgus suberosus , see Harold (1872), Vaurie (1962) and Scholtz (1990); and for additional high-quality images see also Huchet and Costa-Silva (2018) and Costa-Silva et al. (2021).

Figures

Figure 7. Trox suberosus Fabricius, 1775 (now Omorgus suberosus), Neotype, here designated (♂ NHMUK): A. Habitus in dorsal view; B. Habitus in lateral view; C. Aedeagus in dorsal view; D. Aedeagus in lateral view; E. Labels. Scale bars: 1 mm.

Figure 8. Supposed s yntype of Trox suberosus Fabricius, 1775 (= Trox monachus Herbst, 1790) from Joseph Banks collection (NHMUK): A. Habitus in dorsal view; B. Patricia Vaurie’s handwritten note about the type specimen; C. Type labels. Scale bar: 1 mm. Photo by Keita Matsumoto (NHMUK).

Figure 9. Trox suberosus ’ descriptions provided by Johan Christian Fabricius in his publications of A. 1775; B. 1781; C. 1787; D. 1792; and E. 1801.

Figure 10. Alleged s yntype of Trox suberosus Fabricius, 1775 (= Trox sp.) from Fabricius collection (ZMUK): A. Habitus in dorsal view; B. Habitus in fronto-lateral view; C. Type labels. Photo by Michael Kuhlmann (ZMUK).