The Passalidae, or bess beetles, are a family of about 500 beetles (Coleoptera) within one of the main clades of the superfamily Scarabaeoidea. Adults are relatively large, ranging 20-70 mm (0.75-2.75 inches) long, roughly cylindrical, shiny black beetles with ridged elytra, strong jaws, and lamellate antennae. Larvae have the typical scarabaeiform larval shape and appearance, but do not exhibit the C-shaped curl of other Scarabaeoidea and possess a pair of highly reduced hind legs, such that the larva appears to have only four legs rather than six. Passalid beetles are found world-wide, mainly in the tropics. In the United States, the family is represented by just two species: the widespread Odontotaenius disjunctus and the similar, less well-known species O. floridanus, which is known to occur only in a small area in Florida and was described in 1994.
The ecology of the Passalidae, especially species in the Old World, is not well known. While most feed and live in logs in advanced stages of decay, a few are associated with leaf litter collected by arboreal fern rhizomes or even found in the waste chambers of leaf cutter ants (Attaspp.), which are also rich in decaying plant matter.
Most of our knowledge on passalid life history is inferred from observation and experimentation on O. disjunctus. The Passalidae are unusual among the Coleoptera in that most species, if not all, are presocial, ie. they live in small family groups of multiple long-lived individuals that cooperate in rearing offspring. Both male and female adults excavate galleries in rotting logs, engage in defense against competitors, and feed the offspring pre-chewed wood, which the larvae cannot ingest otherwise. Larvae and recently metamorphosed adults also feed on adult fecal pellets, which aid digestion. Adults cooperate to assist larval offspring or siblings in the construction and repair of a pupal case out of wood and feces. Because the development time from egg to adult occurs in only a few months, while adult lifespan can reach years, a group of sexually mature adults in an established gallery can potentially rear multiple broods of offspring over their life time. Both larvae and adults of O. disjunctus can produce sound by, stridulation the former using the extremely reduced hind legs and the latter with their wings. While there is some evidence for the adaptive value of adult stridulation for deterring predation, showing aggression, and courtship, the function of stridulation in communication between adults and larvae within the colony is less clear.
Odontotaenius disjunctus is one of several recorded hosts for the tachnid fly Zelia vertebrata, whose larvae somehow penetrate the galleries to burrow into and feed within the bodies of the well-hidden beetle larvae. Other predators of the Passalidae probably include generalist vertebrates such as birds, rodents, or large mammals that find the beetles by searching for nests in logs and breaking open the galleries. The economic importance of bess beetles is minor and lies primarily in the service they provide as part of the community of organisms that decompose decaying plant matter and return carbon into the soil.
(Cotinis et al 2013; Gray 1946; Mahoney 2009; Schuster 1975; 1984, 1994, 2005; Schuster and Schuster 1997, 1985; Buchler et al. 1981; Browne and Scholtz 1999)
- Browne, J. and C.H. Scholtz, 1999. A phylogeny of the families of Scarabaeoidea (Coleoptera). Systematic Entomology 24(1): 51-84. Retrieved 20 May 2013 from http://onlinelibrary.wiley.com/doi/10.1046/j.1365-3113.1999.00067.x/abstract;jsessionid=B7A86D183CB16400134583247E292176.d03t01?deniedAccessCustomisedMessage=&userIsAuthenticated=false.
- Buchler, E.R., T.B. Wright, and E.D. Brown 1981. On the functions of stridulation by the passalid beetle Odontotaenius disjunctus (Coleoptera, Passalidae). Animal Behaviour. 29(2): 483-486. Retreived 20 May 2013 from http://www.sciencedirect.com/science/article/pii/S000334728180108X.
- Cotinis, Cresswell, S., Harpootlian, P., and Quinn, M. 13 May 2013. "Species Odontotaenius disjunctus - Horned Passalus." Bugguide. Iowa State University. Retrieved 20 May 2013 from http://bugguide.net/node/view/2864.
- Gray, I.E. 1946. Observations on the Life History of the Horned Passalus. American Midland Naturalist. 35(3): 728-746. Retrieved 20 May 2013 from http://www.jstor.org/stable/2421554.
- Mahoney, S.J. 2009. Taxonomic and Host Catalogue of the Tachinidae of America North of Mexico: Genus Zelia. Tachnidae Resources. North American Dipterists Society. Retrieved 20 May 2013 from http://www.nadsdiptera.org/Tach/CatNAmer/Genera/Zelia.htm.
- Schuster, J. C., 1984. Passalid Beetle (Coleoptera: Passalidae) Inhabitants of Leaf-Cutter Ant (Hymenoptera: Formicidae) Detritus. Florida Entomologist. 67(1): 175-176. Retrieved. 21 May 2013 from http://www.jstor.org/stable/3494119.
- Schuster, J.C. 1975. Comparative behavior, acoustical signals, and ecology of New World Passalidae (Coleoptera). Diss. University of Florida, Gainesville. Retrieved from http://ufdc.ufl.edu/UF00099152/00001
- Schuster, J.C. 2005. "Passalidae." Generic Guide to New World Scarab Beetles. University of Nebraska State Museum. Retrieved 20 May 2013 from http://museum.unl.edu/research/entomology/Guide/Scarabaeoidea/Passalidae/Passalidae-Overview/PassalidaeO.html.
- Schuster, J.C. and L.B. Schuster, 1985. Social Behavior in Passalid Beetles (Coleoptera: Passalidae): Cooperative Brood Care. Florida Entomologist. 68(2): 266-272. Retrieved 20 May 2013 from http://www.jstor.org/stable/3494359.
- Schuster, J.C. and L.B. Schuster, 1997. "The evolution of social behavior in Passalidae (Coleoptera)." pp. 260-269 in The Evolution of Social Behavior in Insects and Arachnids, J.C. and B.J. Crespi. Cambridge University Press.
- Schuster, J.C., 1994. Odontotaenius floridanus new species (Coleoptera: Passalidae): a second U.S. passalid beetle. Florida Entomologist. 77(4): 474-479. Retrieved 20 May 2013 from http://www.jstor.org/stable/3495701.
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimens with Sequences:121
Specimens with Barcodes:85
Species With Barcodes:20
Passalidae is a family of beetles known variously as "bessbugs", "bess beetles", "betsy beetles" or "horned passalus beetles". Nearly all of the 500-odd species are tropical; species found in North America are notable for their size, ranging from 20–43 mm, for having a single "horn" on the head, and for a form of social behavior unusual among beetles.
Bodies elongate-cylindrical and black overall; ventral surfaces may be covered with yellow setae. The head is narrower than the thorax, with antennae consisting of 10 antennomeres with a three-segment club. The elytra are elongate with parallel sides, and heavily striated.
They are subsocial (brood caring) beetles living in groups in rotting logs. They care for their young by preparing food for them and helping the larvae construct the pupal case. Both adults and larvae must consume adult feces which have been further digested by microflora for a time; an arrangement that might be described as a sort of external rumen.
In addition, they are also able to produce fourteen acoustical signals, more than many vertebrates. Adults produce the sounds by rubbing the upper surface of the abdomen against the hind wings. The larvae produce the sounds by rubbing the third leg against a striated area on the coxa of the second leg.
Of North American species, Odontotaenius disjunctus (synonym: Popilius disjunctus) is the familiar bessbug found throughout the eastern US and Canada, while O. floridanus has only been found in Florida on sand hills that used to be islands when Florida was flooded thousands of years ago. Ptichopus angulatus was recently discovered near the border of Mexico in Arizona. Its habitat is south to Colombia and it is commonly associated with the detritus chambers of leafcutter ant nests (Atta spp.). Two other species were reported from Arizona at the beginning of the 20th century, but have not been seen there since that time; they may have been brought from Mexico by a train hauling firewood.
- Genus Aceraius
- Genus Ceracupes
- Genus Chondrocephalus
- Genus Cylindrocaulus
- Genus Heliscus
- Genus Leptaulax
- Genus Odontotaenius
- Odontotaenius disjunctus (patent-leather beetle)
- Odontotaenius floridanus
- Odontotaenius striatopunctatus
- Genus Ogyges
- Genus Oileus
- Genus Passalus
- Passalus affinis
- Passalus caelatus
- Passalus elfriedae
- Passalus inops
- Passalus interruptus
- Passalus interstitialis
- Passalus jansoni
- Passalus latifrons
- Passalus pugionifer
- Passalus punctatostriatus
- Passalus punctiger
- Passalus spiniger
- Passalus unicornis
- Genus Paxillus
- Genus Pentalobus
- Genus Petrejoides
- Genus Popilius
- Genus Proculus
- Genus Ptichopus
- Genus Publius
- Genus Spasalus
- Genus Spurius
- Genus Verres
- Genus Veturius
To request an improvement, please leave a comment on the page. Thank you!