Having a look for the shape of the genital papilla is propably the best and most efficient way to differ the sexes in all genera of the subfamily. After a specimen got mature, the papilla is formed in a distinctive shape.
Male
Female
The genital papilla of a male loricariinae specimen is thin and pointed.
In some species the plate lacking area surrounding the papilla is shaped compressed.
Female loricariinae specimen have a thick and blunt genital papilla.
The plate lacking area surrounding the papilla can be shaped elongated in some species.
Secondary sexual differences
Breeding odontodes on headsides
One of the most known secondary difference of the sexes are the breeding odontodes of mature males.
Male
Female
According to the concrete species the breeding odontodes at the headsides of a mature male can differ in size and shape. In some species it is just developed during the breeding season, some other do not have a temporal restriction. Attention: It is known that females of a few loricariinae species also can develop breeding odontondes at the headsides. That was proved for some female specimen of Sturisoma festivum and Sturisomatichthys tamanae.
Next to the breeding odontodes on the headsides, mature males can develop also breeding odontodes on the pectoral fins.
Male
Female
There are 2 different types of the development of breeding odontodes on pectoral fins. The first one concerns just the pectoral spine. On that spine mature males of Lamontichthys, Harttia or Harttiella develop spiky odontodes. These odontodes often are just developed temporarily during the breeding season. The seconds type with a plenty of straight odontodes all over the fin is known from species of Rineloricaria senu lato.
The males of some few species have thicked pectoral spines.
Male
Female
In some loricariinae species with rarely secondary sexual differences the males have slightly thicked spines of the pectoral fins. This difference is visible after they got mature.
Often the head of male loricariinae specimen seems to be broader than the head of females.
Male
Female
This characteristic is developed more or less in all species of the subfamily. Sometimes it is really conspicuous, but mostly it is attended by the breeding odontodes on the headsides of male specimen.
Some lipbrooding species develop enlarged lower lips during breeding season.
Male
Female
The males of the lipbrooding species out of the Loricaricariithys-Group develop a remarkable enlarged lower lip during the breeding season. With that enlarged lipstructure the batch of eggs is enclosed as good as possible to carry until the fry are hatched. The males of lipbrooding species from other evolutionary groups as Loricaria-Group or Pseudohemiodon-Group with fine branched lips don't show that remarkable enlargement of the lower lip.
