Dicaelus dilatatus
Say, 1823
notched-mouthed ground beetle
Dicaelus dilatatus is a of in the , first described by Thomas Say in 1823. The species belongs to the Dicaelus, commonly known as notched-mouthed ground beetles. It occurs in North America with two recognized : Dicaelus dilatatus dilatatus and Dicaelus dilatatus sinuatus. Like other members of its genus, it is a predatory inhabiting terrestrial environments.
Pronunciation
How to pronounce Dicaelus dilatatus: //dɪˈsiːləs ˌdaɪləˈtætəs//
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Identification
Members of the Dicaelus can be distinguished from similar by their characteristic notched (upper lip), which gives the group its . Within the genus, D. dilatatus can be separated from by subtle differences in pronotal and elytral proportions, though precise diagnostic features require examination of detailed taxonomic . The D. d. sinuatus was described by Ball in 1959 and differs from the nominate subspecies in aspects of elytral serration and body proportions.
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Habitat
Based on a field observation in Missouri, Dicaelus dilatatus has been found in xeric rhyolite prairie (glade) , specifically in moss-covered rocky areas under trees within igneous glades surrounded by dry post oak woodland. This aligns with the general habitat preferences of the Dicaelus, which typically occupies dry, rocky, or sandy terrestrial habitats.
Distribution
North America. Distribution records indicate presence in Canada and the United States. The has been documented in the central United States, including Missouri (Iron County), based on field observations.
Seasonality
An was observed in late May (May 15, 2022) in Missouri, suggesting spring to early summer activity. This timing is consistent with the general seasonality of in temperate North America.
Behavior
The single documented observation describes the crawling over moss-covered rocks under a tree during daylight hours. Like other , it is likely primarily in activity pattern, with daytime observations representing incidental surface activity.
Ecological Role
As a member of the , D. dilatatus functions as a in soil and litter , contributing to regulation of and in its .
Similar Taxa
- Dicaelus purpuratusAnother common North Dicaelus with overlapping range; distinguished by differences in body proportions and elytral microsculpture
- Dicaelus ambiguusSimilar size and preferences; requires examination of male or detailed pronotal/elytral proportions for definitive separation
- Other Licininae ground beetlesSimilar general body form; Dicaelus distinguished by the notched characteristic of the
More Details
Subspecies
Two are recognized: Dicaelus dilatatus dilatatus (Say, 1823) and Dicaelus dilatatus sinuatus (Ball, 1959). The latter was described based on specimens with modified elytral serration patterns.