Ptereleotris rubristigma (Ptereleotridae), FB

Ptereleotris rubristigma
Adult
©BH
Ptereleotris rubristigma
Adult
©BH
Ptereleotris rubristigma
Young
©JPH
Ptereleotris rubristigma
Juvenile
©BH

Identification

Confidence: high (adults), low (juveniles)

P. hanae and P. rubristigma are closely related species and their distribution overlaps.

Adults

Adult P. hanae are easy to ID based on their caudal fin filaments that are never present in P. rubristigma. Adult P. rubristigma have an elongated second dorsal spine, a distinct red spot on the pectoral base and a broad dark stripe along the lower body that can run onto the caudal. However, the red spot can be 'switched off' so absence of the spot is not conclusive. Moreover, there are images that suggest P. hanae can have an extended second dorsal, although perhaps less prominent.

Juveniles

There is no well-documented data on the differentiation between juveniles. In Dauin (Philippines) a common juvenile form has the dark lower body stripe of adult P. rubristigma and it can run onto the caudal as a streak of basal spot. A metallic cyan or yellowish stripe runs just above it. There are also juveniles with a solid metallic yellowish body, lacking the dark stripe. Whether the presence/absence of the dark body stripe differentiates P. hanae/rubristigma, respectively, I do not know. Similarly I do not know if the metallic blue and yellowish forms, often of the same size and seen mixed together, represent different sexes, species, or are just a natural variation. The P. rubristigma species description states that an elongated 2nd dorsal spine is present in some but not all young specimens. I have seen it on one image but most of the time they do not raise their first dorsal fin.

Settlers

Settlers are translucent with a prominent silvery airbladder. A dark stripe along the attachment of the anal is more prominent, or appears earlier, than a dark stripe along the attachment of the soft dorsal. A short vertical dark bar is located on the base of the caudal and a yellow patch is present dorsally on the peduncle. The yellow patch can still be found on early juveniles. Species differentiation at this stage is unknown and likely both species have settlers that look very similar.


Sighting localities

Sighting depth range

Depth range: 0.0 - 23.82

Sighting temperature range

Temperature range: 27.0 - 29.0


Created by: Bart Hazes
Last update: 2023-11-26