Hemiancistrus Bleeker, 1862

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Hemiancistrus sp., photo by K.S. Cummings

Hemiancistrus medians, photo from Isbrücker, 1992
Click to see other pictures of H. medians

 
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    • Hemiancistrus has long been used as a repository for species with unclear relationships.  With improvements to the taxonomy expressed in these web pages and to be expressed in an upcoming manuscript, hopefully Hemiancistrus will be the only garbage can genus left in Hypostominae.  It is likely that either Peckoltia and Hemiancistrus share species or that the species of Peckoltia actually belong in Hemiancistrus.  Many undescribed species best fit the definition of Hemiancistrus (which is basically if it isn't something else, then its Hemiancistrus) making Hemiancistrus an exciting avenue for future research.  Herein, two groups are separated from Hemiancistrus, the H. annectens group which represents an undescribed sister genus to Pterygoplichthys, and H. landoni which represents an undescribed genus sister to all other Ancistrini.  A complete understanding of Peckoltia and Hemiancistrus awaits a thorough revision of both genera.  The following is an excerpt from Armbruster (1997).

    SPECIES

    H. brevispinis (Heitmans et al. 1983) 1
    H. braueri Eigenmann 1912
    H. macrops (Kner 1854)
    H. medians (Kner 1854)
    H. megacephalus (Günther 1868)
    H. longispinis Heitmans et al. 1983

    1 Paratypes of Lasiancistrus brevispinis (CAS 53133) lack the whiskerlike odontodes that diagnose Lasiancistrus.  The species is very similar to Hemiancistrus sp. shown above, differing mainly in the length of the cheek odontodes; L. brevispinnis belongs in Hemiancistrus.


    DIAGNOSIS

    Hemiancistrus is not a monophyletic group.

    DESCRIPTION

    Hemiancistrus is an elusive genus.  I am not fully confident that the species referred to Hemiancistrus form a monophyletic group.  Isbrücker (1992) provides a redescription of H. medians, the type of the genus. H. medians is unlike the species that were available to me. H. medians has a short, broad, deep body, and the dorsal fin is large, reaching the adipose fin when depressed.  Because I am unsure whether the specimens used in the phylogenetic study form a monophyletic group with H. medians, I defer discussion of Hemiancistrus until it can be further analyzed.


    COMPARISONS
    Separating Hemiancistrus from Peckoltia  is difficult and some species placed in Peckoltia may actually be members of Hemiancistrus. Hemiancistrus differs from Peckoltia mainly in color pattern with Peckoltia tending to have saddles posterior to the dorsal fin and Hemiancistrus having spots, mottling, or entirely gray (a notable exception is P. oligospila which is well spotted). H. landoni can be identified from typical Hemiancistrus by range, it occurs west of the Andes in the Gulf of Guayaquil drainage and no other typical Hemiancistrus occur west of the Andes.

    ECOLOGY

    Prefers flowing-water habitats in medium to large rivers.


    DISTRIBUTION

    Described species from the Guianas.  Undescribed species potentially in Hemiancistrus are found throughout the Amazon, the upper Orinoco, and the Guianas.


    LITERATURE CITED

    Armbruster, J.W. 1997. Phylogenetic relationships of the sucker-mouth armored catfishes (Loricariidae) with particular emphasis on the Ancistrinae, Hypostominae, and Neoplecostominae. Unpubl. Ph.D. dissertation. University of Illinois, Urbana-Champaign. 409 pp.

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    • If you have any comments or questions regardng this site, please contact Jon Armbruster at armbrjw@mail.auburn.edu