Nemateleotris helfrichi Randall & Allen, 1973
Helfrichs' dartfish
Nemateleotris helfrichi
photo by Tanaka, H.

Family:  Microdesmidae (Wormfishes), subfamily: Ptereleotrinae
Max. size:  6 cm TL (male/unsexed)
Environment:  reef-associated; marine; depth range 0 - 90 m
Distribution:  Southeastern Pacific: Fr. Polynesia.
Diagnosis:  Dorsal spines (total): 7-7; Dorsal soft rays (total): 29-30; Anal spines: 1-1; Anal soft rays: 25-27. This species is distinguished by the following characters: D VI, I,30 (I,29-30); A I,26 (I,25-27); pectoral-fin rays 20 (20-21); pelvic-fin rays I,5; segmented caudal-fin rays 17; upper procurrent caudal-fin rays 9 (9-14); lower procurrent caudal-fin rays 12 (11-12); total caudal-fin rays 37-43; gill rakers 6 (5-7) + 17 (17-18) = 23 (22-24). Colouration: elevated part of first dorsal fin blue on anterior edge; median fins are pale yellowish green, caudal fin no markings, outermost edge of second dorsal and anal fin tipped with a yellow or orange spot, one in each interradial membrane space, the spots sometimes coalescing; when alive the body is lavender to lilac; pelvic fins black-tipped; dorsal edge of iris with a black mark at 1 o’clock position, sometimes continuing until interorbital space as a short streak; maxilla black (when alive and preserved); snout bright pink in life (Ref. 128599).
Biology:  Occurs in relatively deep water. Found over small patches of sand, rubble, or hard open bottoms of steep seaward reefs. Rarely found in less than 40 m and frequently occurs in pairs. Monogamous (Ref. 52884). Feeds on zooplanktons (Ref. 89972). Minimum depth reported taken from Ref. 128797.
IUCN Red List Status: Least Concern (LC); Date assessed: 12 March 2015 Ref. (130435)
Threat to humans:  harmless


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