Skip to main content Skip to main navigation menu Skip to site footer
Responsive image
Issue: Vol. 5845 No. 1: 3 Jul. 2026
Type: Article
Published: 2026-07-03
DOI: 10.11646/zootaxa.5845.1.5
Page range: 106-128
Abstract views: 39
PDF downloaded: 0

Revalidation of Trox raduloides Kolbe, 1904 as a distinct species from Omorgus (Afromorgus) tuberosus (Klug, 1855) (Coleoptera: Trogidae), and description of two new species

Ditsong National Museum of Natural History; PO Box 413; Pretoria 0001; South Africa; School of Life Sciences; University of KwaZulu-Natal; Private Bag X01; Scottsville 3209; South Africa
Invertebrate Biosystematics and Conservation Group; Department of Zoology & Entomology; University of Pretoria; South Africa
Coleoptera Omorginae Scarabaeoidea Afrotropical Region southern Africa keratin beetle lectotype taxonomy

Abstract

Omorgus (Afromorgus) tuberosus (Klug, 1855) has long been regarded as a widespread species in the Afrotropical Region, with Trox raduloides Kolbe, 1904 treated as its junior synonym. However, discrepancies observed in the morphology of type specimens, most notably in the structure of the male genitalia, suggest that O. (A.) tuberosus represents a species complex rather than a single variable species. In this study, we re-examined the type material of O. (A.) tuberosus and T. raduloides, together with additional specimens from museum collections, to clarify the taxonomy and morphological variation within O. (A.) tuberosus sensu lato. Consistent differences in external morphology and aedeagal structure support the reinstatement of T. raduloides as a valid species, here transferred to the genus Omorgus (subgenus Afromorgus). Two additional species closely allied to O. (A.) tuberosus, O. (A.) abyssiniensis Strümpher & Costa-Silva, sp. nov. and O. (A.) scholtzi Strümpher & Costa-Silva, sp. nov. are described and illustrated. Our examination further revealed a high incidence of misidentifications in museum material, largely attributable to inadequate specimen preparation and the historical underuse of male genital characters. By clarifying diagnostic characters, stabilising nomenclature, and recognising previously overlooked diversity, this study provides a more robust species framework for the Omorgus tuberosus species complex and highlights the need for continued revisionary work within Afrotropical representatives of the subgenus Afromorgus. An updated checklist of Afrotropical Afromorgus species, differential diagnoses and distribution map for the treated taxa is provided.

References

  1. Arrow, G.J. (1912) Scarabaeidae: Acanthocerinae, Aclopinae, Dynamopinae, Glaphyrinae, Hybosorinae, Idiostominae, Orphninae, Pachypodinae, Troginae. In: Junk, W. & Schenkling, S. (Eds.), Coleopterorum Catalogus. Pars 43. W. Junk, Berlin, pp. 1–66.
  2. Arrow, G.J. (1927) A note on the coleopterous genus Trox, with descriptions of a few new Asiatic species. Annals and Magazine of Natural History, Series 9, 19 (112), 465–468. https://doi.org/10.1080/00222932708655516
  3. Braack, L.E.O. (1986) Arthropods associated with carcasses in the northern Kruger National Park. South African Journal of Wildlife Research, 16, 91–98.
  4. Brivio, P.C. (1959) Contributo alla conoscenza della fauna coleotterologica della Guinea Portoghese. III. Dytiscidae, Tenebrionidae, Curculionidae, Trogidae. Atti della Società italiana di scienze naturali e del Museo civico di storia naturale di Milano, 98, 372–378.
  5. Chown, S.L., Le Lagadec, M.D. & Scholtz, C.H. (1999) Partitioning variance in a physiological trait: desiccation resistance in keratin beetles (Coleoptera: Trogidae). Functional Ecology, 13, 838–844. https://doi.org/10.1046/j.1365-2435.1999.00373.x
  6. Erichson, W.F. (1843) Beitrag zur Insecten-Fauna von Angola, in besonderer Beziehung zur geographischen Verbreitung der Insecten in Afrika. Archiv für Naturgeschichte, 9 (1), 199–267.
  7. Fåhraeus, O.J. (1857) Familia XXVII. Scarabæides. In: Boheman, C.H. (Ed.), Insecta Caffrariae annis 1838-1845 a J. A. Wahlberg collecta amici auxilio suffultus descripsit. Pars II. Coleoptera. Ex officina norstedtiana, Holmiae [Stockholm], 395 pp. https://doi.org/10.5962/bhl.title.9375
  8. Haaf, E. (1954) Die afrikanischen und orientalischen Arten der Gattung Trox (Col. Scarab). Entomologische Arbeiten aus dem Museum G. Frey, 5, 326–393.
  9. Haaf, E. (1955) Troginae (Coleoptera, Lamellicornia). Parc National de l’Upemba. I. Mission G. F. de Witte 1946–1949. Institut des Parcs Nationaux du Congo Belge, 38 (3), 45–50.
  10. Harold, E. (1869) Scarabaeidae. In: Gemminger, M. & Harold, E. (Eds.), Catalogus coleopterorum hucusque descriptorum synonymicus et systematicus. Tomo IV. Sumptu E.H. Gummi, Monachii, pp. 979–1346.
  11. Harold, E. (1872) Monographie der Gattung Trox. Coleopterologische Hefte, 9, 1–192.
  12. Hodson, A. (1922) Notes on Abyssinian Lakes. The Geographical Journal, 60 (1), 65–67. https://doi.org/10.2307/1780998
  13. Klug, J.C.F. (1855) Diagnosen der neuer Coleopteren aus Mossambique. Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königlichen Preussischen Akademie der Wissenschaften zu Berlin, 20, 643–660.
  14. Klug, J.C.F. (1862) Coleoptera. In: Peters, W.C.H. (Ed.), Naturwissenschaftliche Reise nach Mossambique auf Befehl seiner Majestät des Königs Friedrich Wilhelm IV in den Jahren 1842 bis 1848 ausgeführt. Zoologie V. Insecten und Myriapoden. Georg Reimer, Berlin, pp. 145–267, pls. 8–15.
  15. Kolbe, H.J. (1904) Über einige interessante Lamellicornier und Tenebrioniden Afrikas. Berliner Entomologische Zeitschrift, 49, 282–302.
  16. Kolbe, H. (1910) 7. Coleoptera. 18, Scarabaeidae: Troginae, Melolonthinae, Rutelinae, Dynastinae, Trichiinae, Valginae und Cetoniinae. In: Sjöstedt, Y. (Ed.), Wissenschaftliche Ergebnisse der Schwedischen Zoologischen Expedition nach dem Kilimandjaro, dem Meru und den umgebenden Masaisteppen Deutsch-Ostafrikas 1905-1906. Tryckt hos P. Palmquists Aktiebolag, Stockholm, pp. 341–362.
  17. Kolbe, H. (1914) Scarabaeiden. In: Schubotz, H. (Ed.), Wissenschaftliche Ergebnisse der Deutschen Zentral-Afrika-Expedition 1907–1908 unter Führung Adolf Friedrichs, Herzogs zu Mecklenburg. Band V, Zoologie III. Klinkhardt & Biermann, Leipzig, pp. 261–416.
  18. Krajcik, M. (2012) Checklist of the world Scarabaeoidea. Animma.x, Supplement, 5, 1–278.
  19. Palestrini, C., Barbero, E. & Zunino, M. (1992) Biology of the preimaginal stages in trogid beetles (Coleoptera): Experimental data. Italian Journal of Zoology, 59 (1), 69–71. https://doi.org/10.1080/11250009209386650
  20. Péringuey, L. (1901) Descriptive catalogue of the Coleoptera of South Africa (Lucanidae and Scarabaeidae). Transactions of the South African Philosophical Society, 12, 1–920. https://doi.org/10.1080/21560382.1901.9525977
  21. Peters, W.C.H. (1862) Naturwissenschaftliche Reise nach Mossambique auf Befehl Seiner Majestät des Königs Friedrich Wilhelm IV., in den Jahren 1842 bis 1848 ausgeführt. Zoologie. Band 5: Insecten und Myriopoden. Georg Reimer, Berlin, 566 pp. https://doi.org/10.5962/bhl.title.52323
  22. Philips, J.R. (2009) The mite (Acarina) fauna of trogid beetles (Coleoptera: Trogidae). International Journal of Acarology, 35 (1), 1–17. https://doi.org/10.1080/01647950802709843
  23. Preudhomme de Borre, A. (1886) Catalogue des Trogides décrits jusqu’à ce jour, précédé d’un synopsis de leurs genres et d’une esquisse de leur distribution géographique. Annales de la Société Entomologique de Belgique, 30, 54–82.
  24. Scholtz, C.H. (1978) The occurrence and distribution of Trox in the Kruger National Park. Koedoe, 21, 81–89. https://doi.org/10.4102/koedoe.v21i1.963
  25. Scholtz, C.H. (1980) Monograph of the genus Trox F. (Coleoptera: Trogidae) of subsaharan Africa. Cimbebasia Memoir, 4, 1–104.
  26. Scholtz, C.H. (1982) Catalogue of world Trogidae (Coleoptera: Scarabaeoidea). Entomology Memoir, Department of Agriculture and Fisheries, Republic of South Africa, 54, 1–27.
  27. Scholtz, C.H. (1983) A new species of Trox F. (Coleoptera: Trogidae) from Senegal with new distributional records for other African species. Journal of the Entomological Society of Southern Africa, 46 (2), 205–208.
  28. Scholtz, C.H. (1986) Phylogeny and systematics of the Trogidae (Coleoptera: Scarabaeoidea). Systematic Entomology, 11, 355–363. https://doi.org/10.1111/j.1365-3113.1986.tb00186.x
  29. Scholtz, C.H. (1991) A new species of Omorgus Erichson (Coleoptera: Trogidae) from west Africa. The Coleopterists Bulletin, 45 (2), 112–114.
  30. Strümpher, W.P., Huchet, J.-B. & Costa-Silva, V. (2025) Phoberus sulcatus (Thunberg, 1787) sensu lato: in-depth morphological analysis of male genitalia reveals three cryptic species (Coleoptera: Scarabaeoidea: Trogidae). Zootaxa, 5660 (3), 301–329. https://doi.org/10.11646/zootaxa.5660.3.1
  31. Strümpher, W.P. & Kalawate, A.S. (2023) Omorgus (Omorgus) khandesh (Coleoptera: Scarabaeoidea: Trogidae), a new species from India, along with an annotated catalogue of the Oriental and Palearctic species of the subgenus Omorgus Erichson, 1847. Zootaxa, 5231 (5), 501–522. https://doi.org/10.11646/zootaxa.5231.5.1
  32. Strümpher, W.P. & Stals, R. (2021) Proper cleaning of keratin beetles reveals a cryptic species: Phoberus fumarius (Haaf, 1953) from southern Africa is reinstated as valid (Coleoptera: Trogidae). Zootaxa, 4942 (4), 543–557. https://doi.org/10.11646/zootaxa.4942.4.3
  33. Strümpher, W.P., Villet, M.H., Sole, C.L. & Scholtz, C.H. (2016) Overview and revision of the extant genera and subgenera of Trogidae (Coleoptera: Scarabaeoidea). Insect Systematics & Evolution, 47 (1), 53–82. https://doi.org/10.1163/1876312X-46052133
  34. Zídek, J. (2013) Checklist and bibliography of the Trogidae (Coleoptera: Scarabaeoidea). Insecta Mundi, 314, 1–38.
  35. Zídek, J. (2017) Updated checklist and bibliography of family Trogidae (Coleoptera: Scarabaeoidea). Folia Heyrovskyana, Series A, 25 (1), 93–127.

How to Cite

Strümpher, W.P. & Costa-Silva, V.D. (2026) Revalidation of Trox raduloides Kolbe, 1904 as a distinct species from Omorgus (Afromorgus) tuberosus (Klug, 1855) (Coleoptera: Trogidae), and description of two new species. Zootaxa, 5845 (1), 106–128. https://doi.org/10.11646/zootaxa.5845.1.5