Phanaeus (beetle)

Phanaeus, the rainbow scarabs,[1] is a genus of true dung beetles in the family Scarabaeidae (scarab beetles), ranging from the United States to northern Argentina, with the highest species richness in Mexico.[2][3] Depending on species, they can inhabit a wide range of habitats, from tropical to temperate climates and deserts to rainforests. In those living in relatively arid places adults are primarily active during the wet season and those living in relatively cold places are primarily active during the summer.[4] They are excellent diggers and good fliers.[4]

This article is about the genus of beetles. For the Apollo Greco-Roman epithets, see Phanaeus (epithet).

Phanaeus
male Phanaeus vindex
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Scarabaeidae
Tribe: Phanaeini
Genus: Phanaeus
MacLeay, 1819

They are up to about 2.5 cm (1 in) long and most (but not all) species have bright metallic colors with males having a horn on their head and/or one or two spikes on the pronotum.[2][3] Males of several species occur in two distinct morphs, referred to as "major" and "minor", that differ in body size and size/presence of horn/spikes.[2][3]

Behavior
Phanaeus difformis pair (female below right) at dung in Rosamond Gifford Zoo, United States

Both adult and young of Phanaeus are generally coprophagous, feeding primarily on dung from a wide range of mammals, but they tend to prefer wet, as opposed to dry, dung.[2][4] A pair of Phanaeus will tunnel in the soil below the dung to make nests where some of the dung is placed and the eggs are laid (each egg having its own, typically pear-shaped piece of dung).[2][4][5] This means that they are paracoprids, as opposed to some other dung beetles that dig into or on the underside of the dung (the endocoprids) or roll dung balls overland to a tunnel elsewhere (the telecoprids);[5][6] however, Phanaeus may on occasion roll or push a piece of dung some distance overland from where it was dropped to a tunnel.[2] Because they bring the dung underground, tunneling species like Phanaeus are particularly useful for dung degradation.[5] After the eggs have been laid the parents provides no further care for them.[2][5] The development from egg to adult typically lasts a few months and adult beetles have lived for more than a year in captivity, but their lifespan is probably shorter in the wild.[5] A tunnel with dung also serves a temporary living quarter for a single adult or a pair and is only left once the food supply is exhausted or inedible; adults of some species will overwinter in their tunnel.[2]

Exceptions are two South American species, P. bispinus and P. meleagris, that are mostly necrophagous (certain other species may be both coprophagous and necrophagous), and the Mexican P. halffterorum that appears to be mycetophagous.[2][4]

In species with clearly distinct male morphs, either will pair up with a female to excavate a tunnel, but during male-male encounters a battle ensues with the major morph winning over the minor morph.[2] Females may also fight other females over a piece of dung.[2] In certain species where males vary clinally in appearance (no discrete morphs), like P. difformis, small and hornless "sneaky" males that mate by stealth exist.[2]

Species
Male Phanaeus adonis is found in Mexico (also ranging into far southern Texas), like almost half the species in the genus[1][3]
Male Phanaeus amethystinus showing its iridescent blue color and horn on the head
Male Phanaeus triangularis texensis, which often is considered its own species[3]

Phanaeus includes the following species:[7]

References
  1. "Genus Phanaeus - Rainbow Scarabs". BugGuide. Retrieved 27 June 2023.
  2. Price, D.L.; May, M.L. (2009). "Behavioral ecology of Phanaeus dung beetles (Coleoptera: Scarabaeidae): review and new observations". Acta Zoológica Mexicana. 25 (1). doi:10.21829/azm.2009.251621.
  3. Zídek, J.; Edmonds, W.D. (2012). "Taxonomy of Phanaeus revisited: Revised keys to and comments on species of the New World dung beetle genus Phanaeus MacLeay, 1819 (Coleoptera: Scarabaeidae: Scarabaeinae: Phanaeini)". Insecta Mundi. 2012 (274): 1–108. doi:10.5281/zenodo.5182095.
  4. Edmonds, W.D. (1994). "Revision of Phanaeus Macleay, a New World genus of Scarabaeine dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae)". Contributions in Science. 443: 1–105. doi:10.5962/p.208079. S2CID 90679530.
  5. Paris, T.; Rohde, B.; College, H.; Kaufman, P. (1 July 2013). "Rainbow scarab - Phanaeus vindex Macleay". Featured Creatures. University of Florida Institute of Food and Agricultural Sciences. Retrieved 27 June 2023.
  6. "Dung Beetles". University of Nebraska-Lincoln. Retrieved 27 June 2023.
  7. Biolib


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