Scientists have described two new species of marine goby from the Western Pacific which live alongside partner shrimps.
John Randall, Kwang-Tsao Shao and Jeng-Ping Chen described the two species as Ctenogobiops mitodes and C. phaeostictus in the latest issue of the journal Zoological Studies.
Ctenogobiops mitodes was caught at Pratas Reef in the South China Sea, and at Enewetak Atool lagoon in the Marshall Islands.
The species is very similar in appearance to Ctenogobiops pomastictus and was initially misidentified as this species:
"It is most similar to C. pomastictus Lubbock and Polunin (type locality, Great Barrier Reef), differing in having an elongate 2nd dorsal spine as an adult, 46-52 scales in longitudinal series on the body (compared to 55-59 for C. pomastictus), and 1 instead of 2 rows of dark spots on the cheek."
The new species has a pale white-beige base colour and numerous dark spots, which help it blend in with the substrate while burrowed in a hole alongside its shrimp partner.
Most of the specimens in the type series are around 3-5cm in length.
Ctenogobiops phaeostictus was caught in a lagoon in Madang Province, Papua New Guinea in 1987 and was described from a single specimen. The holotype is a sexually mature female measuring only 2.4cm in length, making this a particularly small Ctenogobiops.
The authors wrote: "It is distinguished from the 8 other species of the genus by having 13 instead of 10-12 soft rays in the dorsal and anal fins, an elongate 3rd dorsal spine, and a unique color pattern of numerous small dark spots, a single longitudinal row of 5 large black spots, and the apparent absence of a white spot on the pectoral fins."
For more information see the paper: Randall JE, Kwang-Tsao S and C Jeng-Ping (2007) - Two New Shrimp Gobies of the Genus Ctenogobiops (Perciformes: Gobiidae), from the Western Pacific. Zoological Studies 46(1): 26-34 (2007).