Arcular Chordotonal Organs in Beetles (Insecta, Coleoptera)

Irina Shumakova and Leonid Frantsevich

Schmalhausen Institute of Zoology, Nat. Acad. Sci. of Ukraine, Kyiv, Ukraine

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Femoral chordotonal organs (FCOs) in beetles differ from those in orthopterids in origin of a FCO apodeme: directly from the tibia in locusts and stick insects (they measure the joint angle), amidst the tendon of the extensor muscle in beetles (those may be sensitive also to strain in the tendon). In 20-25% of beetle species, the FCO apodeme pops up from the tendon as a short motile sclerite (the arculum), curved in Polyphaga, straight in Adephaga. The arculum is connected to scoloparia with 1, 2 or more ligaments. In an amputated leg, the arculum turns distally upon bending of the tibia. The angle of turn in the arculum is up to 20 times more then the turn of the tibia. The system behaves as a high pass filter with a time constant close to the step frequency. The ampified signal is transmitted to the FCO via a terminal ligament.

The arculum was found by I. S. and studied by both authors at various aspects: shape of the arculum (if exists) in various taxa, biomechanics, matched neural activity in the FCO, evolutionary aspects. Results have been published in 1985-2003 in eight articles (seven in Russian), but they are still unknown for foreign readers and did not stimulate any other studies of this unique structure. A short illustrated review of our observations would be published elsewhere, as well as some new investigations. All original texts and the list of studied beetle species (>350) are available from this Web site.

List of studied species: Click Total.xls

Photocopies of original publications

Frantsevich, L. I., and Shumakova I. D. (1985). Arcular chordotonal organ in Coleoptera (in Russian). Reports Acad. Sci. USSR 282, 469-473.

[Францевич, Л. И., Шумакова, И. Д. 1985. Арцеллярный хордотональный орган у жесткокрылых. Доклады АН СССР 282, 2: 469-473.] Click DAN.pdf

Frantsevich, L. I., and Shumakova I. D. (1987a). Biomechanics of the arcular apparatus in the arcular chordotonal organ in beetles (Insecta, Coleoptera) (in Russian). Sensory Systems 1, 39-46.

[Францевич, Л. И., Шумакова, И. Д. 1987. Биомеханика арцеллярного аппарата в арцелярном органе жесткокрылых (Insecta, Coleoptera). Сенсорные системы 1, 1: 39-46.] Click Biom.pdf

Frantsevich, L. I., and Shumakova I. D. (1987b). Evolution of structure and function of the arcular apparatus in beetles (Coleoptera) (in Russian). Rev. d’Entomol. URSS 66, 735-745.

[Францевич, Л. И., Шумакова, И. Д. 1987. Эволюция структуры и функции арцеллярного аппарата у жесткокрылых (Coleoptera). Энтомол. обозрение 66, 4: 735-745.] Click EnRev.pdf, Plates.pdf

Frantsevich, L. I., and Shumakova, I. D. (1993). The luxury of evolution: elaborated structure without evident function. In Sensory Systems of Arthropods (eds. Wiese, K., Gribakin, F. G., Popov. A. V. and Renninger, G.), pp. 670-674. Birkhauser Verlag, Basel, Boston, Berlin. Click Biona.pdf

Shumakova, I. D. (1989). Electrophysiological study of the arcular chordotonal organ in the beetle femur (in Russian). J. Evol. Biochem. Physiol., iss. 5, 670-674.

[Шумакова, И. Д. 1989. Электрофизиологическое исследование арцеллярного хордотонального органа в бедре у жуков. Журн. эвол. биохим. и физиологии выпуск 5: 670-674.] Click Elphys.pdf

Shumakova, I. D. (1990a). Histological study of the arcular chordotonal organ in the beetle femur (in Russian). J. Evol. Biochem. Physiol., iss. 3, 427-429.

[Шумакова, И. Д. 1990. Гистологическое исследование арцеллярного хордотонального органа в бедре у жуков. Журн. эвол. биохим. и физиологии том\выпуск 3: 427-429.] Click Histo.pdf

Shumakova, I. D. (2003). Peculiar construction of the femoral chordotonal organ in some beetles (Coleoptera) and the suspended sclerite of the extensor tibiae in bugs (Hemiptera) (in Russian). Vestnik Zoologii, Suppl. 10, 164-170.

[Шумакова, И. Д. 2003. Особенности строения бедренного хордотонального органа у некоторых жесткокрылых и висячий склерит сухожидия разгибателя голени у полужесткокрылых. Вестник зоологии, Supplement N 16: 164-170.] Click bugs.pdf

In 80ies, we used videokymography for observation and recording of movements of the arculum in response to small bending in the femoro-tibial joint. Here, we attach several recent videos of oscillations of the arculum in several beetles species in response to a manipulated strain-release of the extensor tendon.

We present our apologies for an old error in translation of the Russian term for a small arc ("дужка") to the Latin (arcellus, instead of arculum).