Thursday, February 8, 2018

[Ichthyology • 2018] Crenicichla ploegi • A New Species of Pike-cichlid of the C. saxatilis Group (Teleostei: Cichlidae) from the Rio Juruena and upper Rio Paraguai Basins in Brazil, with An Updated Diagnosis and Biogeographical Comments on the Group

Crenicichla ploegi 
Varella, Loeb, Lima & Kullander, 2018  


Crenicichla ploegi, new species, is described based on material from the Rio Juruena (Rio Papagaio, Rio do Sangue, Rio Arinos, and Rio Juruena itself) and from tributaries of the upper Rio Paraguai (upper Rio Jauru, upper Rio Cabaçal and upper Rio Sepotuba) in Mato Grosso, Brazil. Crenicichla ploegi is the twenty-third species of the C. saxatilis group. It is distinguished from all other species of the group by the presence of dark spots and vermiculations on snout, interorbital area and dorsally on head in adults vs. dark markings absent or present only in juveniles but absent in adults, and by the presence of a deep and strongly pigmented lateral band present in both juveniles and adults, occupying a depth of 4–6 horizontal scale rows vs. lateral band narrower, occupying a depth of 2–3 horizontal scale rows, and conspicuous only in juveniles and smaller specimens, faded or absent in larger specimens. Diagnostic characteristics of the C. saxatilis group proposed in previous studies were discussed to update the diagnosis of the group, and morphological comparisons among the species included in the group, with biogeographical comments, are provided. The presence of conspicuous dark markings dorsally on the head and the presence of a prominent midlateral band are hypothesized to be paedomorphic characteristics, retained from juvenile conditions in the context of the species of the C. saxatilis group.

Keywords: Pisces, biogeography, coloration, paedomorphy, species groups

FIGURE 5. Crenicichla ploegi, uncatalogued, 60.0 mm SL, from the Rio Juba above the waterfall of Cachoeira do Juba, tributary of the Rio Sepotuba basin, upper Rio Paraguai, Tangará da Serra, Mato Grosso, Brazil (field number SACIB2016100103).Photographed alive in aquarium just after capture by Fernando Dagosta.

FIGURE 4. Crenicichla ploegi, a male (left) and a female (right) photographed alive in the Rio Verde, tributary of the Rio Papagaio, Mato Grosso, Brazil. Photo by Marcelo Krause.

Distribution: Crenicichla ploegi is known both from the upper Rio Paraguai basin, and from tributaries of the upper Rio Juruena, in Mato Grosso state, Brazil.

Etymology: Crenicichla ploegi is named in honor of the Dutch ichthyologist Alex Ploeg, whose PhD thesis dealt with the taxonomic revision, biogeography and phylogeny of Crenicichla, and who published papers on systematics of the genus from 1986 to 1991, describing a total of 23 species, 18 of which still considered to be valid. Since then, he worked as interlocutor between the ornamental fish industry and other institutions worldwide.
Unfortunately, Dr. Ploeg perished with his wife and son in the Malaysia Airlines 17 (MH17) airplane attack in Ukraine on 17 July 2014.

Habitat and ecological notes: Crenicichla ploegi has been collected in a variety of aquatic habitats, but mostly in streams and mid-sized rivers. The type locality is actually an exception, being a large river pool, more than 100 meters wide. Streams and rivers inhabited by C. ploegi possess clear water, a moderate to fast water flow, and rocky bottoms, usually with well-developed riparian forest, although the species has also been collected in rivers with highly disturbed or suppressed riparian forest.

FIGURE 8. Crenicichla ploegi, lower pharyngeal tooth plate [Posteromedial tooth extracted] in dorsal view, from ZUEC 10053, 146.1 mm SL. 

Henrique R. Varella, Marina V. Loeb, Flávio C.T. Lima and Sven O. Kullander. 2018. Crenicichla ploegi, A New Species of Pike-cichlid of the C. saxatilis Group from the Rio Juruena and upper Rio Paraguai Basins in Brazil, with An Updated Diagnosis and Biogeographical Comments on the Group (Teleostei: Cichlidae). Zootaxa. 4377(3); 361–386.  DOI: 10.11646/zootaxa.4377.3.3