Joseph Paul Eldred Morrison (1968) contradicted Hubendick and argued the distinctive shell characters of Newcomb's snail supported the generic name Erinna.

The columella is straight, excavated, and with a curved, elevated, external ridge continued in front into the outer lip which is simple and acute.

The marginal teeth are subquadrate, wider than high, the apex reflected, obliquely produced and bearing five or more blunt, short denticles, of which the inner two are the largest.

No recent surveys for Newcomb's snails have been undertaken in the Hanapēpē watershed, or in any of the large neighboring stream systems, because they are located on privately owned lands and are difficult to reach because of the rough terrain.

Since about 1993, Federal and State agencies, academic researchers, and other interested parties have conducted opportunistic surveys at approximately 50 sites along numerous streams and their associated tributaries and springs on Kaua'i, and have located four previously unknown populations of Newcomb's snail.

Recently, two individual snails were reported from a single site in Limahuli Stream in the Hanalei District of Kauaʻi's north shore.

[3] Recent survey work conducted from 1994 to 2003 limits the known range of Newcomb's snail to small sites located in a total of six watersheds in north- and east-facing drainages on Kauaʻi.

Snails attach eggs to submerged rocks or vegetation and larval stages do not disperse widely; the entire life cycle is tied to the stream system in which the adults live.

Snail dispersal both upstream and downstream within a stream system probably plays an important function in colonizing or recolonizing suitable habitat, particularly microhabitat protected from channel scour.

[3] On the basis of past and recent field observations, the specific habitat requirements of Newcomb's snail include fast-flowing perennial streams and associated springs, seeps, and vertical or overhanging waterfalls.

Consequently, suitable habitat is generally restricted to protected, small, spring-fed tributaries, or to stream segments with overhanging waterfalls that have perennial flows supported by stable groundwater input.

The common element among sites harboring snail populations is that the water source appears to be consistent and permanent, even during severe drought.

[3] It is suspected that the four species of introduced caddisflies Trichoptera are adversely impacting native aquatic invertebrate populations either through competition for space and resources, or because of its large body size and sheer abundance in Hawaiian streams.

Although terrestrial, the rosy glandina will fully immerse itself in water to locate and feed on aquatic molluscs such as Newcomb's snail.

The rosy glandina has been observed on the wet, algae-covered rocks of the Makaleha Stream in close proximity to individual Newcomb's snails, and is believed to prey on them.

Flooding due to hurricanes and tropical storms, catastrophic landslides, drought, infestation by introduced invasive species, and other localized phenomena that occur unpredictably could eradicate Newcomb's snail habitat across significant portions of the island.

[3] Newcomb's snails face a continued threat from human-caused changes to the hydrologic landscape of Kauaʻi, that causes severe degradation of natural aquatic environments.

Such changes include large irrigation, extensive plantation style agriculture diverting water out of both surface waterbodies and groundwater sources.

[3] In 1995, prior to Newcomb's snail being listed as threatened, the County of Kaua`i planned a major water diversion project to capture flow from Makaleha Springs for domestic use.

The application process was continued by the Kaua`i Board of Water Supply and cleared a number of State and local regulatory reviews.

Ultimately, the State Commission on Water Resource Management denied the applicable permits on the basis of numerous unresolved environmental issues, including impacts to aquatic life.

Interaction between the State Division of Aquatic Resources management and staff and our endangered species biologists will assist development of an institutional framework to accomplish effective conservation for the Newcomb's snail.