Anthopotamus verticis
Walker's tusked sprawler

Key Characteristics

Mature individuals of this species are relatively small, averaging 7-11 mm in body length, with forewings of 8-12 mm. The eyes are large and black, the wings translucent, and the three tails are white with faint brownish joinings. The head and thorax, as well as the female abdomen, are pale yellow in color. In males, the abdomen is translucent. Large pink spots covering the abdomen in both sexes are diagnostic. In the subamigo (dun) stage, these spots are not visible and wings and tails are pale yellow. Walker's tusked sprawler nymphs average 10 to 13 mm in body length, and are covered with amber to brown mottlings. The abdomen features a reddish dorsal median stripe bordered by pale brown bands. The nymph's three tails are amber in color and the forked gills are grayish and heavily fringed (Schwiebert 2007). All Anthopotamus nymphs have well-developed mandibular tusks (McCafferty and Bae 1990).

Status and Rank

  • State Status: SC
  • State Rank: SNR
  • Global Rank: G5

Occurrences

No known occurrences in Michigan

Updated 1/31/2017. Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.

Habitat

A species of medium to large rivers (Bright 2011), Walker's tusked sprawler nymphs prefer substrates of coarse gravel or small pebbles (Bae and McCafferty 1994).

Natural Community Types

Methodology

For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Feel free to send questions and comments to Brad Slaughter at slaugh14@msu.edu.

Management

As mayflies spend the majority of their lives as underwater nymphs, emerging only for a short adult period of several hours to a few days, maintaining high water quality is a management priority. Increased sedimentation negatively impacts mayfly species by covering gravel and pebble substrates and filling in the small spaces between stones in which they live (Williams and Feltmate 1992). Maintaining adequate riparian buffers, along with efforts to reduce agricultural/urban runoff and the siltation associated with major construction projects, will help to preserve mayfly habitat. Being among the most sensitive to low pH levels of any aquatic insect group, mayflies are typically the first to disappear from waters becoming increasingly acidified (Earle and Callaghan 1998). Initiatives aimed at reducing acid precipitation may therefore benefit this species. Additionally, drastic population declines caused by industrial pollution and pesticide applications aimed at other species have been well documented (Williams and Feltmate 1992). Not only aquatic insects, but a wide variety of organisms are affected by the degradation of freshwater systems. As the process of population recovery in formerly impacted areas can take many years, the protection of healthy waterbodies is key.

Active Period

Breeding from fourth week of May to fourth week of August

Survey Methods

Adult mayflies can be sampled from mating swarms using a long-handled, fine-mesh nylon net (Leonard and Leonard 1962). There are several methods used to collect nymphs, including substrate sampling using an Ekman or Petersen grab, d-frame net, or naturalists' dredge. Gathering of river stones by hand is another successful method. Collected samples are then rinsed through a series of sieves and specimens hand-picked using forceps (New 1998).

Page Citation

Michigan Natural Features Inventory. 2007. Rare Species Explorer (Web Application). Available online at http://mnfi.anr.msu.edu/explorer [Accessed Mar 27, 2017]

References

Survey References

Technical References