Ancistrus sp. L309
This species looks quite unusual. It has a big mouth, small eyes and nice, greenish spots on it's body and orange fin rays. At first, L309 was thought to be a Baryancistrus species, which says a lot about it's appearance. Only old, full grown males develop the famous head tentacles, and it's a slow growing species.
Facts:
Name: Ancistrus sp. L309
Trade names: Bigmouth Bristlenose, L309
Origin: Rio Tapajos, Brazil
Maximum TL: 10 cm / 4''
L309 is a very rare species in the hobby, as it's not allowed for export from Brazil and among aquarists it's usually overlooked. It's not very demanding though, as long as the water is clean and well filtered. It's fairly unproductive (about 20 eggs per clutch), but not difficult to breed. It's small size makes it perfect even for smaller aquariums.
More info:
http://www.l-welse.com/reviewpost/showproduct.php/product/324/cat/44
http://www.planetcatfish.com/common/species.php?species_id=1665