Ambrysus amargosus

Ash Meadows naucorid

Family: Naucoridae · Class: Insecta · Order: Hemiptera

Conservation status: Threatened

The Ash Meadows naucorid is a small aquatic insect endemic to Ash Meadows in Nye County, Nevada. Adults measure approximately 3-4 millimeters (about the size of a ballpoint pen tip), making this one of the smallest federally protected insects (USFWS 2023). As a member of the family Naucoridae (creeping water bugs), this species displays the typical flattened body form adapted for aquatic life, with powerful raptorial forelegs for capturing prey. Historically and currently, the Ash Meadows naucorid is restricted to an extremely limited range within the Ash Meadows area of southern Nevada. The species is known to occupy flowing water that passes over rock and pebble substrates at Point of Rocks Springs (La Rivers 1953). This represents one of the most restricted distributions of any federally listed insect, with the entire known population confined to a single spring system within Ash Meadows National Wildlife Refuge. The naucorid inhabits spring-fed aquatic environments characterized by flowing water over rocky substrates. The species requires specific microhabitat conditions found in headwater springs where clear, constant-temperature water flows over rock and pebble bottoms. These spring systems maintain relatively stable temperatures year-round and provide the specialized substrate conditions necessary for the species' survival. The alkaline desert springs of Ash Meadows create unique aquatic islands within the surrounding arid landscape. As a voracious aquatic predator, the Ash Meadows naucorid feeds on aquatic insect larvae and other small invertebrates (USFWS 2023). The species hunts by swimming over and through substrate materials, using its specialized forelegs to capture prey. Like other naucorids, it likely employs a sit-and-wait predatory strategy, remaining motionless among rocks and pebbles before striking at passing prey items. Specific details regarding reproduction, seasonal activity patterns, and life cycle duration remain poorly documented, representing significant knowledge gaps for this endemic species. The Ash Meadows naucorid was listed as federally threatened under the Endangered Species Act, with critical habitat designated within Ash Meadows National Wildlife Refuge. The primary threats to this species include habitat modification, water diversion, and the extremely small population size that makes it vulnerable to stochastic events. Historical human activities in Ash Meadows, including water diversions and spring modifications, have reduced available habitat. The species benefits from habitat protection within the 23,000-acre Ash Meadows National Wildlife Refuge, established in 1984. Recovery efforts focus on maintaining spring flow conditions and protecting water quality in the remaining habitat. The species' restriction to a single spring system makes it particularly vulnerable to any environmental changes that could affect water flow, temperature, or substrate conditions at Point of Rocks Springs. Conservation expenditures for the species totaled $30,000 in fiscal year 1999 and $4,000 in fiscal year 1998, reflecting ongoing monitoring and habitat management efforts.

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, and more.