''Aequigidiella'' is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

amphipod Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descr ...

crustaceans Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

. It contains only the species ''Aequigidiella aquilifera''. The genus name derives from a combination of the words ''aequi'' for equal and ''Bogidiella'' for its taxonomic relatives. The species name comes from the Latin for

standard-bearer A standard-bearer, also known as a flag-bearer is a person (soldier or civilian) who bears an emblem known as a standard or military colours, i.e. either a type of flag or an inflexible but mobile image, which is used (and often honoured) as a ...

and refers to structures which are flag-like on the male specimens.

Description

The males of the genus are in size, while females can grow up to . The head has a strongly produced lateral lobe, and the smaller antennal sinus is rounded and distinctly visible. It has seven coxal plates, with the first four overlapping. The first plate is as long as it is wide, while the last six are wider than they are long. The second segment of its first antenna is the longest and the third is the shortest. It has a 2-segmented accessory flagellum with a small, knob-like distal section. Its primary flagellum has nine to eleven segments which are slender and have robust aesthetasks. The second antenna has a bulbous first segment and slender fourth and fifth segments. It has a 5-segmented flagellum and one unstalked aesthetask on the first, second, and fifth segments. Its mandible has a 3-segmented palp. The incisors are very heave and composed of two prongs. It has 13 fine teeth on a triangular right lacinia, while its left lacinia is mobile and has five serrations. The molars are small, and both have long seta.

Similar genera

''Aequigidiella'' shares certain features with the genus '' Artesia'' from Texas; their body shapes are generally alike. Their coxal plates are of similar size and shape, as are the biramous and aequiramous pleopods. The propodus of the first and second gnathopods are also roughly the same shape. However, it differs in its uncleft telson, its mouthparts, the fact that its seventh coxal plate is not smaller than the sixth, and the different second pleopod on the male specimens. '' Spelaeogammarus'' from Brazil is another genus which shares affinities with ''Aequigidiella.'' It is one of few other bogidiellids to have aequiramous pleopods. Additionally, it has analogous large coxal plates and morphologically similar mouthparts. However, it, like ''Artesia'', differs in its telson and gnathopods.

Taxonomy

The holotype specimen of ''A. aquilifera'' is housed at the

Zoological Museum Amsterdam The Zoological Museum Amsterdam (ZMA) was a natural history museum located close to Oosterpark (Amsterdam), Oosterpark in Amsterdam, Netherlands. It was part of the Faculty of Science, Mathematics and Computer Science (Science) of the University ...

along with several paratype specimens. These original specimens were collected by Louis Deharveng and D. Rigal during one of their "Thai-Maros expeditions" and were later described by Lazăr Botoșăneanu and Jan Stock. ''Aequididiella'' appears to be an intermediate between the two related families

Artesiidae Artesiidae is a family of crustaceans belonging to the order Amphipoda Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivo ...

and

Bogidiellidae Bogidiellidae is a family of amphipod crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods ...

, contributing evidence to the idea that the two families should be united.

References

{{Taxonbar, from=Q18589560 Gammaridea