Baryancistrus demantoides WERNEKE, SABAJ PÉREZ, LUJAN & ARMBRUSTER, 2005

Green Phantom Pleco, L200

Etymology

Baryancistrus: from the Ancient Greek βαρύς (barús), meaning ‘heavy’ and the generic name Ancistrus, in reference to the broad, robust body shape of member species.

demantoides: from demantoid, a type of yellowish- to brownish-green garnet, and the Ancient Greek εἶδος (eîdos) meaning ‘to resemble’, in reference to the species’ colour pattern.

Classification

Order: Siluriformes Family: Loricariidae

Distribution

Known only from the area around the confluence of the río Ventauri with the río Orinoco in Amazonas state, Venezuela, and also occurs in the lower reaches of the Ventauri as far as the inflowing río Guapuchi.

Type locality is ‘Rio Ventuari near ornamental fish market in river, 04.07565°N, 066.89285°W, Amazonas, Venezuela’.

Habitat

Collected from spaces between granite bedrock and boulders.

Other loricariid species inhabiting the area around the confluence of the Ventauri and Orinoco include Acanthicus hystrix, Ancistrus macrophthalmus, Baryancistrus beggini, Hemiancistrus subviridis, Hemiancistrus guahiborum, Hypancistrus contradens, Hypancistrus debilittera, Hypancistrus furunculus, Hypancistrus lunaorum, Lasiancistrus schomburgkii, Leporacanthicus galaxias, Leporacanthicus triactis, Panaque nigrolineatus, Peckoltia vittata, Pseudancistrus orinoco, Pseudancistrus pectegenitor, Pseudancistrus sidereus, Pseudolithoxus anthrax, Pseudolithoxus dumus, and Pseudolithoxus tigris.

Maximum Standard Length

The largest specimen in the type series measured 150.5 mm.

Aquarium SizeTop ↑

An aquarium with base dimensions of 120 ∗ 45 cm or equivalent should be the smallest considered.

Maintenance

Best maintained in an aquarium designed to simulate a flowing stream with a substrate of variably-sized rocks, sand, fine gravel, and some water-worn boulders.

This can be further furnished with driftwood branches, roots and tough aquatic plants which can be grown attached to the décor. Bright lighting will promote the growth of aufwuchs upon which the fish will graze.

Like many species that naturally inhabit running waters it is intolerant to the accumulation of organic wastes and requires spotless water at all times in order to thrive. It is also essential to provide sufficient levels of dissolved oxygen and water movement using a combination of canister filters, powerheads, etc., particularly if the aim is to breed the fish. Weekly water changes of 40-70% should be considered mandatory.

Water Conditions

Temperature: 26 – 30 °C; this species will not thrive in cool water.

pH: 5.5 – 7.5

Hardness: 18 – 179 ppm

Diet

Gut analyses of wild specimens revealed the contents to be composed of a ‘mixed brown orgamic and mineral matrix’, within which only strands of filamentous algae could be identified. This suggests that the species feeds by scraping periphyton and sediment from submerged surfaces.

In the aquarium aufwuchs should thus be allowed to colonise all surfaces except the viewing pane so that the fish can browse naturally, although the diet should be supplemented with high-quality, sinking dried foods (preferably with added vegetable content), live or frozen chironomid larvae (bloodworm) and similar, plus slices of fresh fruit and vegetables and the occasional defrosted prawn or shrimp.

Home-made, gelatine-bound recipes containing a mixture of puréed fish food, shellfish, fruit and vegetables, are also proven to work well and in many ways represent the ideal staple diet since specific ingredients can be selected.

Baryancistrus spp. are often under-nourished and/or suffering from health issues post-importation and may require an extended period of quarantine and acclimatisation. They also have a relatively high metabolic rate and and may require several meals per day during this initial period.

Behaviour and CompatibilityTop ↑

Juveniles are relatively peaceful but males in particular become increasingly intolerant of conspecifics as they age, and typically react aggressively towards any other fish viewed as a territorial threat.

It is therefore best kept alongside species that inhabit other areas of the tank, with medium-to-large sized characids particularly suitable. A group can be maintained in larger aquaria provided sufficient territorial space is available and visual barriers considered when laying out the décor.

Sexual Dimorphism

Adult males develop a broader, slightly flatter head profile and longer pectoral-fin spines than females.

Reproduction

Has been achieved in captivity. Eggs are laid and fertilised in a cave, with the female ejected post-spawning and the male responsible for guarding and tending the brood until the free-swimming stage is reached. Any successful attempt is likely to depend on providing a large tank, well-oxygenated water and an excellent diet.

NotesTop ↑

This species is very similar to Hemiancistrus subviridis in appearance and the two occur sympatrically in nature, though B. demantoides is less common and tends to be more expensive in the aquarium trade. Both have been marketed under the DATZ code L200, with B. demantoides sometimes referred to as ‘L200 high-fin’ or ‘L200a’, the former name in reference to its comparatively long dorsal-fin spine (average length in the type series 42.1 mm vs. 34.3 mm in H. subviridis).

It is further distinguished from H. subviridis by presence (vs. absence) of an enlarged membrane connecting the dorsal and adipose fins, and from other loricariids possessing such a membrane by its colour pattern consisting of an olive-to-yellowish base colour with white or cream-coloured spots on the head and anterior portion of the body.

The genus Baryancistrus is diagnosed by the following combination of characters: snout rounded, covered with rough plates, without bristles; interopercle with numerous hooks or spines; body broad and more-or-less depressed; gill openings small; mouth large with long premaxillaries; numerous (up to 80) teeth, arranged in a parallel fashion; dorsal-fin not united to adipose-fin, posterior membrane well-developed (see below); abdomen partially covered by scutelets in specimens of all ages; colour pattern comprising light spots; D = I+7, P = I+5-6, V = i+5, A = i+4, C = i+13+14+i.

Members can be distinguished from all other loricariids by possession of an enlarged membrane located posteriorly to the last branched dorsal-fin ray. This membrane may or may not reach the supporting structure of the adipose fin, and in this way members can be told apart from the genera Oligancistrus, Parancistrus, and Spectracanthicus, in which the dorsal and adipose fins are completely connected, and Hemiancistrus in which the membrane is not well-developed.

The family Loricariidae is the largest among catfishes with over 700 species described to date and many awaiting description. The latter are typically assigned a specific ‘L’ number by hobbyists and scientists alike in order to provide a basic means of identification, although in some cases several species have been referred to the same number, or multiple numbers have been used for different populations of a single taxon. All loricariids are also commonly referred to as ‘pleco’, ‘plecostomus’, or ‘suckermouth armoured catfishes’.

The closer relationships of member genera have long been of interest to ichthyologists but remain largely unresolved. Isbrücker (1980) was the first to propose an arrangement of six subfamilies, namely Lithogeneinae, Neoplecostominae, Hypostominae, Ancistrinae, Hypoptopomatinae, and Loricariinae, and this model was generally followed until publication of Armbruster’s morphological analysis in 2004.

His phylogeny also contained six subfamiles, with Isbrücker’™s (1980) Ancistrinae being included as one of five tribes comprising Hypostominae. This was later modified slightly by Reis et al. (2006) and an adapted version of their key is reproduced here:

1a. No lateral and dorsal plates anterior to the dorsal fin: Lithogeneinae
1b. Possession of lateral plates anterior to the dorsal fin (except in Pareioraphis nudulus): 2
2a. Ventral surface of the pectoral girdle exposed (i.e. supporting odontodes) towards the centre of the coracoid strut: Hypoptopomatinae
2b. Ventral surface of the pectoral girdle covered in skin or plates towards the centre of the coracoid strut (odontodes supported by the plates rather than the girdle): 3
3a. Caudal peduncle flattened dorsoventrally; no adipose fin: Loricariinae
3b. Caudal peduncle oval, round, or triangular in cross-section; adipose fin usually present: 4
4a. Postdorsal ridge formed from several preadipose plates arranged singly. Teeth almost symmetrically bifid (divided into two equal parts): Delturinae
4b. Usually no postdorsal ridge. Teeth asymmetrical or unicuspid: 5
5a. Dorsal–fin spinelet V-shaped, dorsal–fin spine can be locked: Hypostominae
5b. Dorsal–fin spinelet rectangular or absent, dorsal–fin spine cannot be locked: Neoplecostominae

Subsequent papers attempting to resolve relationships within the Hypoptopomatinae and Neoplecostominae by Cramer et al. (2008, 2011) have revealed both subfamiles to be polyphyletic arrangements alongside several genera, e.g., Pareiorhaphis, Pareiorhina, Hisonotus, and Parotocinclus, so there is evidently a great deal of work still to be done. At any rate, Baryancistrus is currently considered a member of the tribe Ancistrini within Hypostominae and grouped in the Panaque clade of that tribe, close to Parancistrus and Hemiancistrus.

The sucking disc formed by the mouthparts is common to all representatives but both oral and dental morphology are highly variable depending on a given species’ ecological adaptation(s). and some even practice xylophagy (wood-eating). Many are also facultative air-breathers, i.e., they possess the ability to respire atmospheric air if necessary.

References

1. Werneke, D. C. , M. H. Sabaj Pérez, N. K. Lujan and J. W. Armbruster, 2005 - Neotropical Ichthyology 3(4): 533-542
   Baryancistrus demantoides and Hemiancistrus subviridis, two new uniquely colored species of catfishes from Venezuela (Siluriformes: Loricariidae).
2. Armbruster, J. W., 2008 - Zootaxa 1822: 1-76
   The genus Peckoltia with the description of two new species and a reanalysis of the phylogeny of the genera of the Hypostominae (Siluriformes: Loricariidae).
3. Armbruster, J. W. , 2004 - Zoological Journal of the Linnean Society 141: 1-80
   Phylogenetic relationships of the suckermouth armoured catfishes (Loricariidae) with emphasis on the Hypostominae and the Ancistrinae.
4. Cramer, C. A., A. M. R. Liedke, S. L. Bonatto, and R. E. Reis, 2008 - Bulletin of Fish Biology 9: 51-59
   The phylogenetic relationships of the Hypoptopomatinae and Neoplecostominae (Siluriformes: 725 Loricariidae) as inferred from mitochondrial cytochrome c oxidase I sequences.
5. Cramer, C. A., S. L. Bonatto, and R. E. Reis, 2011 - Molecular Phylogenetics and Evolution 59(1): 43-52
   Molecular phylogeny of the Neoplecostominae and Hypoptopomatinae (Siluriformes: Loricariidae) using multiple genes.
6. Lujan, N. K., M. Arce, and J. W. Armbruster, 2009 - Copeia 2009(1): 50-56
   A new black Baryancistrus with blue sheen from the upper Orinoco (Siluriformes: Loricariidae).
7. Rapp Py-Daniel, L. , J. Zuanon, and R. Ribeiro de Oliveira, 2011 - Neotropical Ichthyology 9(2): 241-252
   Two new ornamental loricariid catfishes of Baryancistrus from rio Xingu drainage (Siluriformes: Hypostominae).
8. Rapp Py-Daniel, L. H., 1989 - Cybium 13(3): 235-246
   Redescription of Parancistrus aurantiacus (Castelnau, 1855) and preliminary establishement of two new genera: Baryancistrus and Oligancistrus (Siluriformes, Loricariidae).
9. Reis, R. E., E. H. L. Pereira, and J. W. Armbruster, 2006 - Zoological Journal of the Linnean Society 147(2): 277-299
   Delturinae, a new loricariid catfish subfamily (Teleostei, Siluriformes), with revisions of Delturus and Hemipsilichthys.