Hyphessobrycon borealis
Etymology
Hyphessobrycon: from the Ancient Greek υπελάσσων (hyphesson), meaning ‘of lesser stature’, and used as a prefix in this case, plus the generic name Brycon.
borealis: from the Latin boreas, meaning ‘the north wind’, in reference to this species’ distribution in northern South America.
Classification
Order: Characiformes Family: Characidae
Distribution
Has a relatively wide distribution in French Guiana, where it has been recorded from the Oyapock/Oiapoque, Approuague, Kaw, Kourou, Sinnamary, Mana and Maroni river systems.
Type locality is ‘Crique St. Anne, Mana, French Guiana’.
Habitat
Tends to inhabit marginal zones with shallow water and little current, where it forms large schools.
Maximum Standard Length
The largest officially-recorded specimen measured 27.8 mm.
NotesTop ↑
This species can be told apart from congeners by the following combination of characters: largest premaxilary teeth up to quincuspid (with up to 5 cusps); maxilla relatively large (2.68-3.60 times in HL); 18-22 branched anal-fin rays; 29-32 lateral scales; about 10 pored scales in the lateral line; body depth 3.09-4.03 times in SL; head length 3.37-4.00 times in SL; no humeral spot; caudal spot oval, not extending over the whole depth of the caudal peduncle, and only slightly onto the basal parts of the median caudal-fin rays, never reaching the tips.
In its description, H. borealis was considered to be a member of the putative ‘H. heterorhabdus-group’ of closely-related species within the genus as proposed by Géry (1977). This originally comprised around 15 members characterised by a ‘longitudinal pattern’ consisting of a thin, usually dark, lateral body stripe, but has since been modified on a number of occasions.
Most recently, Lima et al. (2014) proposed a putatively monophyletic H. heterorhabdus-group containing only three species; Hyphessobrycon heterorhabdus, H. amapaensis, and H. eschwartzae. These all possess a well-defined, elongate humeral blotch which is continuous with a dark, well-defined midlateral stripe that becomes blurred towards the caudal peduncle.
Hyphessobrycon was raised by Durbin in Eigenmann (1908) as a subgenus of Hemigrammus, differing from the latter by the absence of scales on the caudal-fin.
The grouping was revised by Eigenmann (1918, 1921) while Géry (1977) created artificial groups of species based on colour pattern, and these definitions are still widely used today, e.g., the H. agulha group, the H. heterohabdus group, etc. These cannot be considered to represent monophyletic assemblages, however, and their concepts continue to be redefined.
Weitzman & Palmer (1997) hypothesised the existence of a monophyletic assemblage within the genus based on colour pattern and male fin morphology that they termed the ‘rosy tetra clade’, with one of the characters supporting its monophyly being presence of a prominent dark marking on the dorsal-fin. This assemblage, plus other morphologically similar species, is considered to represent Hyphessobrycon sensu stricto by some authors, with the remaining species included in a much-expanded H. heterohabdus group.
Others have proposed conflicting, typically more restricted, views of both the genus and/or its constituent species groups, and significant confusion remains. What is clear is that, as currently recognised, Hyphessobrycon is a polyphyletic lineage containing several genera.
The process of splitting it up has already started, and Malabarba et al. (2012) revalidated the genus Ectrepopterus Fowler, previously considered a synonym of Hyphessobrycon. They also analysed its relationships within the Characidae in the context of Mirande’s (2010) previous work, but included the type species, H. compressus, for the first time in such a study. The results demonstrated that H. compressus is more closely-related to ‘rosy tetra’ representatives such as H. eques, H. pulchripinnis, and H. socolofi than other members of the genus including H. anisitsi, H. bifasciatus, H. elachys, H. herbertaxelrodi, and H. luetkeni.
References
- Zarske, A., P.-Y. Le Bail and J. Géry, 2006 - Zoologische Abhandlungen, Staatliche Naturhistorische Sammlungen Dresden, Museum für Tierkunde 55: 17-30
New and poorly known characiform fishes from French Guiana. 1. Two new tetras of the genera Hemigrammus and Hyphessobrycon (Teleostei: Characiformes: Characidae). - Géry, J., 1977 - T. F. H. Publications, Inc.: 1-672
Characoids of the world. - Lima, F. C. T., D. P. Coutinho and W. B. Wosiacki, 2014 - Zootaxa 3872(2): 167-179
A new Hyphessobrycon (Ostariophysi: Characiformes: Characidae) from the middle Amazon basin, Brazil. - Malabarba, L. R., V. A. Bertaco, F. R. Carvalho & T. O. Litz., 2012 - Zootaxa 3204: 47-60
Revalidation of the genus Ectrepopterus Fowler (Teleostei: Characiformes), with the redescription of its type species, E. uruguayensis. - Mirande, J. M., 2010 - Neotropical Ichthyology 8(3): 385-568
Phylogeny of the family Characidae (Teleostei: Characiformes): from characters to taxonomy. - Weitzman, S. H. and L. Palmer, 1997 - Ichthyological Exploration of Freshwaters 7(3): 209-242
A new species of Hyphessobrycon (Teleostei: Characidae) from the Neblina region of Venezuela and Brazil, with comments on the putative `rosy tetra clade'. - Zarske, A., 2014 - Vertebrate Zoology 64(2): 139-167
Zur Systematik einiger Blutsalmler oder "Rosy Tetras" (Teleostei: Ostariophysi: Characidae).
