Description:
Ophiophragmus filograneus reaches a disk diameter of approximately 0.2 - 0.3 inches, and has arms measuring 3 inches or more.  The disk is generally gray or brown in color, with the arms irregularly patterned in similar colors.  Disk scales are often darker than the base color of the disk, typically with lighter borders.  The radial shields typically have white tips.  The edge of the disk has 20 or more fence papillae between the arms.  There are 3 arm spines which are significantly longer nearest to the disk than at the ends of the arms.  On the oral side of the disk, and along its outside, tiny cone-shaped papillae cluster in patches.

Habitat:
Ophiophragmus filograneus is endemic to Florida and is one of only a few truly estuarine brittlestars, able to tolerate both brackish and hypersaline conditions.  It is typically associated with the shoal grass, Halodule beaudettei (formerly H. wrightii), and is found in soft mud or woody sediments where this seagrass grows.  It generally is found in water less than 8 feet deep.

Similar Species:
Ophiophragmus filograneus is similar in overall appearance to a related brittlestar, O. wurdemanii, which also inhabits the Indian River Lagoon.  These species are distinguished in that O. wurdemanii grows to a larger size, approximately 0.4 inches in disk diameter, with arms of 5 inches or more.  It also typically has a gray disk with white arms, which are banded irregularly in brown or black. O. wurdemannii also lacks conical papillae on the ventral side of the disk. 

Range:  
Ophiophragmus filograneus is endemic to Florida and ranges from Pensacola Bay on Florida's west coast to the Mosquito Lagoon on the east coast.  It has not been documented in the Florida Keys.