Derolathrus

Sharp, 1908

Jacobson's beetles

Species Guides

Derolathrus cavernicolus(Jacobson's beetle)

Derolathrus is a of minute beetles in the Jacobsoniidae, containing 12 described . The genus includes both extant and extinct species, with fossil records from Cretaceous amber deposits in Myanmar and France. Several species exhibit troglomorphic adaptations, including reduced or absent . The genus has a disjunct global distribution spanning tropical and subtropical regions.

Pronunciation

How to pronounce Derolathrus: //dɛroʊˈlæθrəs//

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Identification

Derolathrus are distinguished from other Jacobsoniidae by their minute size and compact body form. Species-level identification relies on subtle differences in antennal structure, pronotal shape, and male genitalia. Troglomorphic species (e.g., D. anophthalmus, D. cavernicolus, D. troglophilus) are eyeless or have highly reduced , distinguishing them from surface-dwelling .

Habitat

include cave systems, forest litter, and possibly soil or decaying organic matter. Derolathrus cavernicolus has been documented from cave and forested habitats in Florida and Barbados. Several are known exclusively from caves, indicating a degree of subterranean specialization within the .

Distribution

Disjunct distribution including: Florida (USA), Barbados, Hawaii, Guadeloupe, St. John, Montserrat (Lesser Antilles), United States Virgin Islands, Sri Lanka, and various localities in Southeast Asia. Fossil are known from Cenomanian-aged Burmese amber (Myanmar) and Charentese amber (France).

Human Relevance

Some may represent accidental introductions through horticultural trade. Derolathrus cavernicolus represents the first record of Jacobsoniidae from continental North America, highlighting potential biogeographic importance of human-mediated .

Similar Taxa

SarothriasOther in Jacobsoniidae; Derolathrus distinguished by antennal club structure and body proportions

More Details

Fossil record

Four extinct are known from Cretaceous amber: D. abyssus and D. groehni from Burmese amber (Cenomanian, ~99 Ma), and D. capdoliensis from Charentese amber (Cenomanian, France). These fossils indicate the had achieved substantial geographic range by the mid-Cretaceous.

Troglomorphy

At least three extant (D. anophthalmus, D. cavernicolus, D. troglophilus) exhibit troglomorphic features including anophthalmia or microphthalmia, depigmentation, and elongated appendages, suggesting independent evolution of cave within the .