Adult, Lana'i, 25 feet, 33mm

Subadult, Lana'i, 25 feet, 23mm

Lana'i Lookout, Oahu, 15 feet

Uncommon in caverns and under slabs exposed to surge deeper than 10 feet.  Mature adults are dull rusty brown and flattened, with a broad dorsal groove.  Juveniles are tan or blue-gray, inflated and glossy, with blunt extremities.  Attains 1.75 inch.  Endemic to Hawaii.  Hybridizes with Nucleolaria nucleus.

Sharkfin, Lana'i, 25 feet, 22mm

Very rare in caverns or under slabs deeper than 20 feet.  Glossy cream to brown, inflated with protruding extremities, distinct marginal callous, prominent dorsal groove nearly centered, large granules joined by ridges on left side extending onto base.  Attains 1 inch.  Endemic to Hawaii.  This is a hybrid between endemic Nucleolaria granulata and Indo-Pacific Nucleolaria nucleus.  It was described in Severns, 2011 as Nucleolaria hinuhinu, and synonymized by WORMS under N. granulata.

Very rare in caverns or under slabs exposed to surge from 10 to 40 feet.  Glossy grayish-cream to light brown, inflated with protruding extremities, smaller granules mostly uniform in size, connected by ribs extending to the base, both edged with orange-brown, marginal callous barely developed, indistinct dorsal groove skewed to the side.  Attains 1 inch.  Endemic to Hawaii.  This is a hybrid between Indo-Pacific Nucleolaria nucleus and endemic Nucleolaria granulata.  It was described in Severns, 2011 as Nucleolaria pseudonucleus, and synonymized by WORMS under N. nucleus.