Hyphessobrycon eschwartzae
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.
eschwartzae: named for the artist Eugenia Schwartz ‘in gratitude for her economic support which permitted collection of specimens which form part of the type material in this research’.
Classification
Order: Characiformes Family: Characidae
Distribution
This species is currently known only from the Río Madre de Dios watershed in Madre de Dios region, southeastern Peru, where it has been collected from the Tambopata National Reserve plus areas north of the nearby city Puerto Maldonado.
Type locality is ‘La Cachuela, Río Madre de Dios, Tambopata, Madre de Dios, 12°16’38.2″S, 69°09’8.12″W’.
Sexual Dimorphism
Males possess bony hook-like structures on the anal-fin; 5 pairs on the fourth simple ray and 6-10 pairs on each of the first three branched rays.
Females lack these hooks and are also likely to be heavier-bodied than males.
NotesTop ↑
H. eschwartzae is distinguished from other laterally-striped Hyphessobrycon species from the Madre de Dios watershed by the following characters: 4 simple anal-fin rays (vs. 3 in other species listed); 13-15 dentary teeth (vs. 5-11); 6 teeth in the internal premaxillary row (vs. 5); 3 teeth in the external premaxillary row (vs. 4 except in H. heterorhabdus and H. loretoensis, which may have three or four).
It further differs from H. loretoensis in possessing 7 (vs. 9-10) pored scales in the lateral line and 5 (vs. 3-4) scales between the lateral line and dorsal-fin, and from H. heterohabdus by 30-31 (vs. 35-37) lateral scales, 7 (vs. 23-24) pored lateral line scales, 9 (vs. 10) predorsal scales and 4 (vs. 2) maxillary teeth.
It may be distinguished from two other similar species, H. amapaensis and H. montagi, by colour pattern; in the former the dark lateral body stripe is reduced or absent towards caudal peduncle (vs. continuous in H. eschwartzae), and the latter possesses two distinct humeral spots (vs. a single spot in H. eschwartzae).
H. eschwartzae is 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; a longitudinal red stripe extending along the body above the midlateral line; upper half of the eye red.
This pattern is different to that presented by several members of Géry’s H. heterorhabdus group, such as H. vilmae, H. cachimbensis, and H. stegemanni, which possess a continuous, solid dark lateral stripe on the body and no obvious humeral blotch, but is similar to that of Géry’s H. agulha group. The latter contained species with a colour pattern comprising “lower half of the body dark, especially above anal fin; usually a horizontally elongate humeral spot, more or less united with the assymetrical, broad band”, and included H. agulha, H. loretoensis, H. peruvianus, H. metae, and H. herbertaxelrodi.
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
- García-Alzate, C. A., C. Román-Valencia and H. Ortega, 2013 - Revista de Biologia Tropical 61(2): 859-873
Hyphessobrycon taphorni y H. eschwartzae (Teleostei: Characidae) dos nuevas especies de peces de la cuenca del río Madre de Dios, Perú. - Calcagnotto, D., S. A. Schaefer, and R. DeSalle, 2005 - Molecular Phylogenetics and Evolution 36(1): 135-153
Relationships among characiform fishes inferred from analysis of nuclear and mitochondrial gene sequences. - Géry, J., 1977 - T.F.H. Publications, Inc.: 1-672
Characoids of the World. - 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. - Oliveira, C. A., G. S. Avellino, K. T. Abe, T. C. Mariguela, R. C. Benine, G. Orti, R. P. Vari, and R. M. Corrêa e Castro, 2011 - BMC Evolutionary Biology 11(1): 275-300
Phylogenetic relationships within the speciose family Characidae (Teleostei: Ostariophysi: Characiformes) based on multilocus analysis and extensive ingroup sampling. - 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).
