Pterotus obscuripennis
LeConte, 1859
Douglas fir glow-worm
Pterotus obscuripennis, commonly known as the Douglas fir glow-worm, is a of firefly in the Lampyridae. It is to North America and has been recorded primarily in western coastal regions. The species is notable for its bioluminescent larvae, which are referred to as 'glow-worms.' are non-luminous and possess reduced or non-functional mouthparts.
Pronunciation
How to pronounce Pterotus obscuripennis: /tɛˈroʊtəs əbˌskjʊriˈpɛnɪs/
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Identification
males can be distinguished from other Lampyridae by the combination of soft , dark coloration, and association with western coniferous forests. The females are unique among local fireflies in their wingless, -like appearance. Larvae are recognized by their segmented form and . The is separable from the eastern Pterotus marginatus by geographic range and subtle differences in male genitalia.
Images
Appearance
are soft-bodied beetles with dark, somewhat flattened bodies. The are dark brown to black with a slightly velvety texture. Males have fully developed wings and ; females are (retaining larval body form), wingless, and larger than males. Larvae are elongated, segmented, and bioluminescent, with light organs on the underside of the terminal abdominal segments. The specific epithet 'obscuripennis' refers to the dark (obscure) wings.
Habitat
Coastal and montane coniferous forests, particularly those dominated by Douglas fir (Pseudotsuga menziesii). Found in moist, shaded environments with abundant decaying wood and litter.
Distribution
Western North America, from British Columbia south through Washington, Oregon, and into northern California. Records are concentrated in the Pacific coastal region and Cascade Range.
Seasonality
have been observed from June through August. Larval activity likely extends through much of the year in suitable microhabitats.
Life Cycle
Complete with bioluminescent larval stage. Larvae are predatory and inhabit moist forest floor environments. occurs in soil or litter. are short-lived and do not feed; is the sole function of the adult stage.
Behavior
Larvae are nocturnally active that use , possibly for luring prey or as a defensive signal. are to . Males fly in search of sedentary females, which remain on the ground or on vegetation.
Ecological Role
Larvae function as of soft-bodied in forest floor . The contributes to nutrient cycling in coniferous forest through larval foraging activity.
Human Relevance
Serves as an for intact coniferous forest . Occasionally noted by observers for its bioluminescent larvae. No significant economic impact.
Similar Taxa
- Pterotus marginatusEastern North American with similar ; distinguished by distribution and subtle differences in male genitalia.
- Lampyris noctilucaEuropean glow-worm with females; distinguished by geographic separation and different larval pattern.
More Details
Bioluminescence
The produces light through a luciferin-luciferase reaction in larval photophores. The function of larval glow in this species has not been definitively established; hypotheses include prey attraction and aposematic signaling.
Conservation status
Not formally assessed by IUCN. Vulnerable to loss from logging and urbanization of coastal forests. Moist microhabitat requirements make sensitive to drought and climate change.