HYPOSTOMINAE KNER,1853

Armbruster, Jonathan W., 2004, Phylogenetic relationships of the suckermouth armoured catfishes (Loricariidae) with emphasis on the Hypostominae and the Ancistrinae, Zoological Journal of the Linnean Society 141 (1), pp. 1-80 : 58

SUBFAMILY HYPOSTOMINAE KNER,1853

Synonyms:

Ancistri Kner, 1853

Hypostomiden Kner, 1853

Lictores Kner, 1853

Plecostomiformes Bleeker, 1862

Chaetostomidi Fowler, 1958

Includes:

Ancistrini Kner, 1853

Corymbophanini new tribe

Hypostomini Kner, 1853

Pterygoplichthini new tribe

Rhinelepini new tribe

Type genus: Hypostomus Lacépède, 1808 .

Diagnosis: The Hypostominae is diagnosed by a unique characteristic: the lower lobe of the hypural plate longer than the upper (123: 1; Fig. 24B ). Other characteristics considered synapomorphic for Hypostominae are: a long accessory process on the first ceratobranchial (7: 2; Fig. 9E ; reversed in some groups), a small canal plate (83: 1), a V-shaped spinelet (148: 0), and a posteroventral ridge on the basipterygium (173: 1; Fig. 33C, E, F ).

Description: With the inclusion of the Ancistrinae (and exclusion of some genera formerly within it) the Hypostominae becomes the largest of the loricariid subfamilies in number of species (366 currently valid). Size is incredibly variable within the subfamily, which includes small genera such as Lithoxus (50 mm) and the largest of all loricariids, Acanthicus (maximum size probably around 1 m). Hypostomines are typically bulkier than other loricariids and generally have thicker plates than neoplecostomines. The tribe and generic descriptions below provide more information on the diversity of forms.

Comparisons: The best character to distinguish the Hypostominae from most other loricariids is the development of the spinelet. In all the Hypostominae , the spinelet is large and V-shaped and clearly slides under the nuchal plate, whereas it is square or absent in most other loricariids and, when present, does not slide under the nuchal plate. Some hypoptopomatines have a triangular spinelet, but these species can be distinguished from the Hypostominae by a completely or nearly completely exposed pectoral girdle (vs. at most some odontodes supported by the coracoid strut), the adductor fossa of the pectoral girdle covered by bone (vs. wholly exposed), and by having the fenestrae of the pterotic-supracleithrum larger ventrally than dorsally (vs. all fenestrae of about equal size). Delturus also has a triangular spinelet but can be distinguished by the presence of an adipose fin with a postdorsal ridge (all hypostomines with a postdorsal ridge lack an adipose fin). The Chaetostoma group and some Ancistrus have the spinelet covered in skin; these species can be distinguished from the other loricariid subfamilies by the presence of evertible cheek plates with hypertrophied odontodes. The Hypostominae further differs from the Loricariinae by having a round, oval, or triangular cross-section of the caudal peduncle (vs. rectangular and depressed).

Figures

Figure 9. First ceratobranchial, right side, dorsal view. A, Astroblepus sp., MCNG 16251. B, Hypoptopoma sp., INHS 28696. C, Lamontichthys llanero, INHS 29957. D, Isbrueckerichthys duseni, UMMZ 215262. E, Hypostomus cochliodon, UMMZ 20338. Scale bars = 1 mm.

Figure 24. Posterior vertebrae and hypurals, right side, lateral view. A, Neoplecostomus microps, MNRJ 13555. B, Pseudancistrus sp., USNM 226181. Scale bars = 1 mm.

Figure 33. Pelvic basipterygium, ventral view. A, Astroblepus sp., USNM 318209. B, Delturus anguilicauda, USNM 318209. C, Hypostomus plecostomus, ZMA 105.306. D, Kronichthys sp., MZUSP 27545. E, Peckoltia ucayalensis, INHS 40916. F, Pseudorinelepis genibarbis, INHS 39730. Scale bars = 5 mm.