Synonyms
Girardinus caudimaculatus Hensel, 1868
Etymology
- Phalloceros is a term derived from the Ancient Greek words ϕαλλός (phallos), which means ‘penis’, and κέρας (kéras), which means ‘horn’.
- Caudimaculatus, on the other hand, is a word with Latin roots, where cauda means ‘tail’, and maculatus translates to ‘spotted’.
Classification
- Order: Cyprinodontiformes
- Family: Poeciliidae
Distribution
The natural habitat of this species is in Brazil, Paraguay, Uruguay, and Argentina. However, it is noteworthy to mention that feral populations can also be found in Australia, New Zealand, Ethiopia, and Malawi. The introduction of these populations was initially intended for mosquito control, but they are now regarded as invasive.
Lucinda’s research (2008) suggests that this species’ natural distribution includes the Lagoa dos Patos system, lower rio Uruguai, rio Tramandaí, and rio Mampituba located in Rio Grande do Sul state, Brazil. It also encompasses the coastal systems of Uruguay and Argentina.
The type locality of this species is at the Costa da Serra at São Leopoldo in ponds and ditches, referring to the city of São Leopoldo located in the southern Brazilian state of Rio Grande do Sul.
Habitat
This species typically resides in ponds, sluggish rivers, and streams that have dense vegetation. However, it is worth noting that some populations can also be found in slightly brackish water.
Maximum Standard Length
- Male 30 – 35 mm;
- Female 50 – 70 mm.
Aquarium Size
A 50 litre tank is suitable for keeping a trio of these organisms
Maintenance
This species thrives in a well-planted aquarium with gentle filtration, and it appears to be delicate to freshwater. Therefore, it is advisable to conduct small but regular water changes.
Water Conditions
- Temperature: 16 – 22 °C, is best in an aquarium, though it will survive for short periods in temperatures down to 10°C and up to 30°C. Lower temperatures are handled better than higher.
- pH: 7.0 – 8.0
- Hardness: 90 – 447 ppm; populations from brackish habitats are less tolerant of soft water.
Diet
This species is an omnivore and undemanding in terms of food, accepting a wide range of offerings. Its natural diet comprises of grazing algae, small insects, insect larvae, and crustaceans. However, in the aquarium setting, it is receptive to frozen and dry foods.
Behaviour and Compatibility
Should ideally be maintained in a species tank.
Sexual Dimorphism
Males are much smaller than females and possess a prominent gonopodium.
Reproduction
Breeding this species is relatively straightforward, given that they are livebearers. With well-fed parents and densely planted areas in the tank, the fry should be secure with the adult fish.
Male individuals can be persistent in their pursuit of females, so it is recommended to have more females than males in the aquarium.
The gestation period typically lasts between 4-6 weeks, which may vary depending on the temperature. Once born, the fry will immediately feed on microworms and freshly hatched Artemia.
Notes
The colour pattern of this species is highly variable. Within the aquarium hobby, three ornamental forms are well-known and have been given unofficial ‘scientific’ names, which are not italicized here:
- A spotted form, commonly referred to as Phalloceros caudimaculatus ‘reticulatus.’
- A golden form, commonly referred to as Phalloceros caudimaculatus ‘auratus.’
- A spotted golden form, often referred to as Phalloceros caudimaculatus ‘reticulatus auratus.’
Both of the golden forms appear to have a low survival rate under natural conditions.
P. caudimaculatus is the type species of the genus, which was previously monotypic until a significant review was published in 2008, describing 21 new species. Among these, it can be distinguished from P. anisophallos, P. megapolos, P. spiloura, P. reisi, P. buckupi, P. alessandrae, P. lucenorum, P. uai, P. pellos, and P. malabarbai by the female urogenital papilla located between the anus and the base of the first anal-fin ray, along the midline of the body (vs. curved to the right, located laterally; anus in contact with the first anal-fin ray).
It can be differentiated from P. tupinamba, P. leptokeras, and P. aspilos by the female urogenital papilla being straight along the midline (vs. slightly left-oriented), and the absence of a lateral ramus of the female urogenital papilla (vs. presence), and the absence of a hook in the gonopodial appendix (vs. presence).
Furthermore, it can be distinguished from P. enneaktinos, P. titthos, P. elachistos, and P. harpagos by the absence of hooks in both halves of the gonopodial appendix (vs. hook present in both halves). It is distinguished from P. heptaktinos by males having 8 dorsal-fin rays (very exceptionally seven), and females possessing seven rays (very exceptionally eight).
Lastly, it can be differentiated from P. ocellatus, P. mikrommatos, and P. leticiae by possessing a non-ocellated, elliptical and vertically elongated lateral spot that is occasionally absent (vs. lateral spot being roundish to rounded, well-defined, and ocellated).
Thanks for this profile go to Karsten Plesner.
References
- Hensel, R., 1868 – Archiv für Naturgeschichte 34(1): 323-375
Beiträge zur Kenntniss der Wirbelthiere Südbrasiliens. (Fortsetzung). - Dawes, J., 1985 – Blandford: 1-240
Livebearing fishes – A guide to their aquarium care, biology and classification. - Gärtner, G., 1981 – Verlag Eugen Ulmer: 1-152
Zahnkarpfen – Die lebendgebärenden Im Aquarium. - Lucinda, P. H. F., 2008 – Neotropical Ichthyology 6(2): 113-158
Systematics and biogeography of the genus Phalloceros Eigenmann, 1907 (Cyprinodontiformes: Poeciliidae: Poeciliinae), with the description of twenty-one new species. - Wischnath, L., 1993 – T.F.H. Publications, Inc., United States of America: 1-336
Atlas of livebearers of the world.
