Co-authored by by Marco Túlio C. Lacerda, English version edited by Clare Dignall

Preface
Despite the craze for all things Loricariidae in recent years, the dwarf suckermouths of the sub-family Hypoptopomatinae has been given little attention. Exceptions to this (in the German DATZ magazine where this article was originally published) were a small entry in the 'current affairs' column (Hieronimus 1992) and two articles on care and breeding (Evers 1992; Bilke 1992). In addition to this, an interesting catalogue of the two sub families Loricariinae and Hypoptopomatinae was published (Matsuzaki & Miyake 1991). Furthermore, in the last two years, three publications have come out which deal particularly with the breeding of these fish (Elsholz & Elsholz 1992, 1994, Wendenburg 1993).

Introduction
The sub-family Hypoptapomatinae contains 11 genera with over 60 species (Schaefer 1991; Schaefer & Provenzano 1993), of which the genus Otocinclus Cope is best know to aquarists. Schaefer (1991) subdivided the sub-family into two "tribes". The first being the Hypoptopomatini with the genera Acestridium Hasemann, Hypoptopoma Günther, Oxyropsis Eigenmann & Eigenmann, Otocinclus Cope, Microlepidogaster Eigenmann & Eigenmann, as well as an undescribed genus. The second is the "tribe" Otothyrini with the genera Pseudotocinclus Nichols, Otothyris Myers, Pseudotothyris Britski & Garavello, Schizolecis Britski & Garavello and Parotocinclus Eigenmann & Eigenmann.

In recent years, the genus Parotocinclus has been the object of systematic studies at species level by various ichthyologists (Garavello 1977, 1988; Schmidt & Ferraris 1985; Schaefer 1988; Schaefer & Provenanzo 1993). At present 18 species of this genus have been found (Garavello 1977; Schaefer 1991; Schaefer & Provenanzo 1993), spread over the following areas of Brazil: -

Species from the Guyana Shield, bordered in the South from the Amazon, in the West from the Río Orinoco and Rio Negro:

• Parotocinclus britskii Boeseman, 1974, Coppename and Nickerie basin in Surinam, Cuyuni basin in Venezuela and Pará basin in Brazil, state Pará;
• Parotocinclus collinsae Schmidt & Ferraris, 1985, Takutu basin in Guyana;
• Parotocinclus eppleyi Schaefer & Provenanzo, 1993, upper and middle areas of the Orinoco basin in Venezuela;
• Parotocinclus longirostris Garavello, 1988, Rio Preto da Eva and Igarapé Tarumázinho, near Manaus, state Amazonas, Brazil;
• Parotocinclus polyochrus Schaefer, 1988, tributary of the Río Mawarinuma, state Terr. Federal Amazonas, Venezuela.

Species from the Amazon area:

• Parotocinclus amazonensis Garavello, 1977, Ilha Sorubim, Rio Solimões, state Amazonas, Brazil;
• Parotocinclus aripuanensis Garavello, 1988, Rio Canumá, tributary of Rio Aripuaná, upper Madeira basin, state Mato Grosso, Brazil

Species from north-eastern Brazil, rivers on the Atlantic coast:

• Parotocinclus bahiensis (Ribeiro, 1918), Vila Nova (huete Senhor do Bonfirm), state Bahia;
• Parotocinclus cearensis Garavello, 1977, Rio Choró, state Ceará;
• Parotocinclus cesarpintoi Ribeiro, 1939, Rio Paraíba, Quebrangulo, state Alagoas;
• Parotocinclus haroldoi Garavello, 1988, Corrego do Otoviano and Riacho Sanharó, state Piaui;
• Parotocinclus minutus Garavello, 1977, Rio Vasa-Barris, Canudos, state Bahia;
• Parotocinclus spilosoma (Fowler, 1941), Campina Grande, state Parába;
• Parotocinclus spilurus (Fowler, 1941), Rio Salgado, Içó, state Ceará.

Species from the eastern and south-eastern Atlantic coastal rivers in Brazil:

• Parotocinclus cristatus Garavello, 1977, Fazenda Almada, Ilhéus, state Bahia;
• Parotocinclus doceanus (Ribeiro, 1918), Rio Doce, state Espirito Santo;
• Parotocinclus jimi Garavello, 1977, Rio do Peixe, small tributary of the Rio de Contas, Itagibá, state Bahia;
• Parotocinclus maculicauda (Steindachner, 1877), southern coastal rivers in Brazil, from Santa Catarina to Espirito Santo.

Despite this large number of species, only Parotocinclus maculicauda is generally known as an aquarium fish, having been exported from the Rio de Janeiro area since around the early 1980's. Many studies of their breeding habits (Franke 1961; Sands 1984; Morris 1985; Elsholz & Elsholz 1993) and fine illustrations of them (Richter in Sands 1984; Yamazaki in Matsuzaka & Miyake 1991; Evers 1992; Franke in Wendenburg 1993) have been published. So it is not deemed necessary to discuss this species any further here.

Since 1992 we have been able to catch for ourselves, or to obtain certain rare examples of Hypoptopomatini, principally Parotocinclus species, and rear them in the aquarium. They come mainly from Northeast Brazil, one of the 3 largest semi-desert areas of South America, known by the Portuguese name of "Nordeste" (Lacerda 1994 a and b).

Their behaviour in the aquarium, including in some cases even their reproductive behaviour, was studied for lengthy periods up to 2 years. Most of the species described in this article have not ever been dealt with before in the specialist literature.

Additionally we show the relevant measurement data in tabular form from preserved material. After measurements were taken this was given to the Amsterdam Institute for Systematics and Population biology (Zoological Museum of Amsterdam - ZMA), in order to facilitate a distinction of the presented species (with exception of Parotocinclus sp. "Recife", of which preserved material was already present). The measurement criteria are taken from Garavello (1977) and are:

• Standard length: of the Ethmoid up to the base of the caudal.
• Body height: measured before the base of the first dorsal ray.
• Head length: from the Ethmoid to the rear edge of the Operculum.
• Body width: Space between outside edges of the Cleithrum.
• Eye diameter: Measured horizontally.
• Interorbital distance: shortest distance between the eyes.

Parotocinclus cristatus Garavello 1977
Five individuals (ZMA 121.258), 26.2 to 35.7 millimetres standard length (mm SL); Rio Tariri, branch / tributary of the Rio Almada, Ilhéus, Bahia, Brazil, 21/12/1992, M.T.C. Lacerda, S. Valerio, V. Alves.

During an excursion into the Nordeste in December 1992 (Lacerda 1994 a) we succeeded in discovering Parotocinclus cristatus. Garavello (1977) described this species on the basis of eleven individuals collected by a Mr. Pereira in February 1945 in Fazenda Amada, close to Ilhéus in the Federal State of Bahia. We found it to a narrow brook that flows into the Rio Almada, likewise in the proximity of Ilhéus. The city is close to the Atlantic coast rain forest, thus not in dry area. The brook was not deeper than a meter and about eight meters wide; the water was quite clear and fast flowing. Contrary to Parotocinclus maculicauda, which predominantly is found in flooded onshore vegetation, P. cristatus lives on stones and submerged tree trunks. This gives rise to the name the locals call these fish "chupapedras" (stone licker or stone sucker), a name which is used also for other Parotocinlcus species of the Nordeste (Garavello 1977).

Also living here and sharing a habitat with P. cristatus were Hypostomus sp., Aspidoras sp. (shown in Lacerda 1994 b as A. cf. maculosus Nijssen & Isbrücker), Nematocharax venustus Weitman, Menezes & Britski (see Lacerda 1994 a, there labelled as 'Ultra Sailfin Tetra'), Astynax sp., "Geophagus" cf. brasiliensis, a pike shaped dog characin of the tribe Acestrorhynchini and an unclassified Characide.

Investigations revealed that P. cristatus was also found in two further tributaries of the Almada although in small numbers. In one of these tributaries a further interesting pleco shares the same habitat. This was exported by the firm Trop-Rio exports under the description Hypostomus unae and which was introduced under the number LDA17 (Schraml 1994). Pareiorhaphis bahainus Gosline, 1947 is also exported by this firm.

A few of the fish from this habitat have reached Germany and already a thorough report on care and breeding has been published (Elsholz & Elsholz 1994). After W and K B Elsholz (1994 and personal communications) bred a single male and three alternating females in an 80 litre tank (water conditions pH 7.0, 15 °dH, 25°C). The eggs have a diameter of around 1.5mm and are therefore larger than those of Parotocinclus maculicauda and those of Otocinclus species. The fish never produced more than ten fertilized eggs per spawning. This is probably because of the lack of sufficient numbers of males. In the peak season the group spawned almost weekly. The rearing was very successful with TetraOvin and trout pellets. An absolutely clean breeding tank is of greatest importance (the floor and sides must be kept free of bacteria (slimy 'lawns' of bacteria)) with crystal clear water. The young P. cristatus grew in eight weeks to a size of 16mm.

As with all Parotocinclus species, these dwarf fish need only small aquarium with water flowing as fast as possible, generated by a reliably working pump or an efficient filter. Along with quite normal fish food like daphnia, cyclops, frozen mosquito larvae and so on, the dwarf suckermouths also require vegetable food like lettuce, spinach, or peas. All Parotocinclus known up until now react very sensitively to a deterioration of water quality in captivity. Given a decrease in water quality, they are always the first fish to hang on to the side just under the surface and try to get out of the water. This must be watched if, for example, a massive increase of infusorien has occurred.

Parotocinclus jimi Garavello, 1977
Four specimens (ZMA 121.257) 26.0 to 30.85mm SL; Rio do Peixe, Brazil, 12/1994, D Byron. In August 1994 the collectors of the Trop Rio export company organized a trip in order to make this kind of aquarium fish accessible to the external market. Garavello (1977) had described them using specimens that were caught in 1973 and '74 in the Rio Contas system in a river flowing in isolation in the Nordeste. Despite the fact that the type locality was not really that far from the place where P. cristatus was found, it is in a region of almost desert-like character and one that, for most of the year, has a dry climate. As well as the Terra Typica, the Rio do Peixe was visited. This flows into the Rio Gongoji that in turn drains into the Rio de Contas. The Rio do Peixe has its source in the mountains and has many waterfalls along its path. Parotocinclus jimi could only be found in areas where the water was very turbulent and where much brown jellylike algae grew. One of the authors had observed similar in a clear water stream in Venezuela near Puerto Ayucucho. There, however, the colour of the layers (of algae) was a deep green.

Helmut Dittmar, Hamburg was good enough to examine the sample from Venezuela brought along in formalin. It was a question of this thin green layer of algae, not yet ascertainable, which was covered with a thick layer of bacteria and was consequently presented a very useful substratum for infusorien and insect larvae.

Parotocinclus jimi could never be caught in submerged land vegetation as is normal for P. maculicauda, or sitting on stones as P. cristatus is reported to do. Both of these species appear to live sociably, they were always observed in large groups. Parotocinclus jimi on the other hand lives in isolation, in smaller groups.

Right beside the waterfalls lived a further Loricariidae similar to C. bahainus. Other sorts of fish that were found in the river were "Geophagus" cf. brasiliensis, Astynax sp. and Poecilia reticulata.

Three dams have destroyed a few of the earlier waterfalls of the Rio do Peixe. They were built five or six years ago. The local inhabitants use the artificial lakes as reservoirs and places for bathing with bars, showers etc. P. jimi was probably seen more often before the construction of these dams. No dwarf suckermouth catfish were found in the Rio de Contas. Admittedly, the work of the collectors was hindered by a massive occurrence of water hyacinth, Eichhornia sp. that covered large areas of the water surface.

The first weeks of keeping P. jimi in an aquarium have confirmed what the origin of the fish led us to suspect. They need a lot of oxygen and are even more sensitive to infusorien than P. cristatus. As opposed to the daytime activity of P. cristatus, P. jimi does not become active until dusk and at night.

Parotocinclus cf. cesarpintoi Ribeiro 1939 and Hypostominae 'Quebrangulo'
Parotocinclus cf. cesarpintoi, three specimens (ZMA121.260) 24.0 to 28.75mm SL, Rio Paraiba do Norte, Quebrangulo, Alagoas, Brazil, 27 and 28. 12. 1992 M. T .C Lacerda, S Valerio, V Alves. Hypostominae sp. five specimens (ZMA 121.259) 24.1 to 33.4mm SL, other data as ZMA121.260.

In 1939, Paolo de Miranda, an ichthyologist from the Museo Nacional in Rio de Janeiro described a new Parotocinclus from the Nordeste and named it in honour of its collector P. cesarpintoi. The description consisted of three black and white photos, one of a pair of the new species and two of the place of discovery, the Rio Paraiba near the village of Qebrangulo in the state of Algoas. The original description is really kept very short but Garavello (1977) portrayed the species more thoroughly.

During a journey through the Nordeste in December 1992 it was also possible to visit the place of discovery of P. cesarpintoi. The Rio Paraiba (actually Rio Paraiba do Norte as opposed to Rio Paraiba do Sul, one of the largest rivers in the southwest of Brazil) around the town of Quebrangulo is very heavily polluted; there were no Loricariidae to be found here. The only 'survivors' are Tilapia introduced from Africa. In Ribeiro's description, the Rio Paraiba shown was near the town by a bridge, this area is now very heavily polluted. In talking with the locals it came out that further upstream a dam had been constructed for the water supply of the town of Palmeira do Indios. The water remains unpolluted there. We reached this place by a narrow, treacherous horse path. We collected two small dwarf suckermouths that at first we took to be members of the sub family Hypoptopomatinae. One of the species was quite dark, almost black with small green metallic spots, mostly in the region of the head. This one stayed near stones. The second was brighter with golden flecks with particularly unusual shape. We caught it on the sandy bed. Only a little water was flowing the Rio Paraiba and many sandbanks were visible (it was the dry season and most of the rivers in the Sertáo in the Nordeste completely dry up: Lacerda 1994 a). The water was very clear and transparent, fast flowing and during the day reached 35°C and more! The number of dwarf suckermouths was very high and obviously these fish needed such high temperatures. Other species encountered were Tilapia which have probably replaced the "Geophagus" brasiliensis.

We had the opportunity of following the river a few kilometers upstream on foot. During this walk, we could see thousands of the second brighter species through the shallow water. Isaac Isbrücker was good enough to give expert advice on these fish afterwards. He ascertained that it was apparently a species of the sub family Hypostominae that remained very small! Young specimens lay in the shallower areas of water on the sand; the older and fully grown fish, never larger than four to five cm total length, were concentrated around larger stones in the deeper part of the river (from about a meters depth). We feared that the high temperatures would eventually result in overheating of the fish collection bags. However, this concern turned out to be unfounded as all the fish survived capture and transit unharmed.

The Hypostominae species is by far more common than Parotocinclus species. Measurements of the former produced a few differences to the details in the original description; a more thorough examination was not possible because of the lack of materials for comparison. Therefore, we describe this species for the time being as P. cf. cesarpintoi.

In two years of captivity clear differences in behavior of the two species was recognized. P. cf. cesarpintoi is a typical member of its genus, which only becomes noticeably active and goes looking for food in reduced light. In the early morning and in the evening after the lights have been switched off, one can observe that the fish leave their quiet places of rest (dark corners of the tank, pieces of wood or holes) and graze on the objects. The Hypostominae species on the other hand is also active during the day. These fish eat any food offered in large quantities. Both sexes gorge themselves so full that the observer believes ha has only pregnant females in front of him. The males however become slim again very quickly and besides can be distinguished from the fatter females by an orange brown are on the upper side of the head which is sometimes visible.

When the fish sense danger they bury themselves in the fine sand. This behavior has not been previously reported in members of Hypostominae. The second Hypostominae from Pernambuco shows the same behavior. Likewise, the supposed courtship behavior of these dwarves is interesting: the male does a kind of hopping dance around the female. He sits on the ground near the females head and suddenly performs three or four jumps from one side of the females head to another: sometimes he also jumps over her body at the same time or presses his body against the females. We were able to observe this unusual behavior three times altogether but no spawning followed. Perhaps an increase in temperature could have triggered the spawning (the fish were kept at 22 to 24°C).

Apparently both kinds were larger in the aquarium that in the natural habitat. At the end of September 1994 the aquarium specimens of P. cf. cesarpintoi measured 37.3mm (female), the smallest (male) at least 32.7 mm (SL). The largest female of the Hypostominae measured 43.0, the male 40.9, (SL).

Parotocinclus haroldoi Garavello, 1988
Three specimens (ZMA 121.256) 33.6 to 34.7mm SL, Rio dos Mato (branch of the Rio Longa, Rio Parnaiba system) Piripiri, Piaui, Brazil 27.12.1993 M.T.C. Lacerda, V. Alves.

In December 1993 another trip to the Nordeste was undertaken, mainly in search representatives of the genus Aspidoras (Lacerda 1994 b). After a few collection expeditions in the state of Ceara, we flew from Fortaleza to Teresina, in the state of Piaui so that we could travel from there by car northeast on the BR343. Teresina lies near Rio Parnaiba, one of the largest rivers in the Nordeste with immense Galerie forest, which in its vegetation is reminiscent of the amazonian rainforests, near Belem. Along the road the surroundings became drier and drier, almost desertlike as in Ceara. The rivers in Campo Maior, the next largest city after Teresina, were all dried up. It took us a further 80 km to find water in a branch of the Rio Longa. It looked more like a stream full of stones with very shallow water. We were able to catch Crenicichla cf. lepidota there, Hypostomus sp., Ancistrus and the most beautiful Parotocinclus we had ever known. On a background of black brown, the fish had yellow orange coloured spots, similar for example to the Ancistrine L4.

We did not come across these dwarf suckermouths that often. We were able to capture only about 20 in total. They lived in the crevices between the rocks so that they could not be caught in our nets but required us to collect them by hand. One by one, they were collected from the niches in the rocks. A comparison of measurements confirmed the suspicion that we were dealing with P. haroldoi. Garavello does not mention the unique spotted markings as they disappeared in the preserved specimens. The place where the type species was found, 'Córregeo do Otaviano, Poco do Sanharó, Riacho Sanharó' likewise belongs to the region of the inlet of the Rio Parnaiba.

Parotocinclus sp. 'Rio Cristalino'
Five specimens (ZMA 121.261) 16.4 to 19.2mm, Rio Crisstalino (branch/tributary of the Rio das Mortes) Rio Araguaia system, Mato Grosso, Brazil, 7.1994, S. & P. Valerio da Silva. 34 specimens (ZMA121.262) not measured similar data to ZMA 121.261.

In July 1994 an interesting 'Mini Parotocinclus' came into our hands through two travelling aquarium fish hunters, Savio and Paulo Valeria da Silva. They had caught these fish in small stream-like tributaries of the Rio Cristalino. The water of these streams was absolutely clear to a depth of 50 cm, the river bed consisted of fine white sand. The dwarf suckermouths live in the bends in the places where the water flow is faster. They cling to the vegetation that hangs into the water from the bank which these are mainly grasses. The following species live here side by side: Apistogramma sp. (A. regani-group), Cichla sp., Hyphessobrycon sp., Iguanodectes sp., Thayeria boehlkei, Imparfinis minutus, Brycon sp., Corydoras cf. araguaiaensis, Phractocephalus hemioliopterus, Pseudoplatystoma fasciatum and Potamotrygon sp.

The most noticeable feature of this new species is its small size. The fish grow no bigger that 20mm (SL). Their heads are proportionately very long (see table). The collectors of these fish, collecting from January to November never found specimens of more than 2.5 cm (total length). The smallest Parotocinclus species so far described is P. amazonensis at 15mm long. In this context it should be noted that all Guyana-shield and Amazonian Parotocinclus catfish have a standard maximum obtainable length under 30mm. The species of the Atlantic rainforest reach mostly 35mm length (SL) and more (apart from P. minutus and P. doceanus).

15 specimens of these dwarves are kept at present in a 40 litre aquarium. The tank is densely planted (Najas and Limnophila), the substrate is fine white sand and the temperature varies between 25°C by day and 27°C by night. The small suckermouth catfish are fed with Artemia-Naupali, frozen Cyclops pellets and fallen leaves. The first females ready to spawn have already been observed.

Mostly small groups of four or five fish sit on the plant leaves or on the side of the tank, a fish alternates his position back and forth swimming a little through open water. The colouring gets brighter at night, this species is obviously more active in daytime.

Parotocinclus sp 'Recife' and Hypostominae sp 'Recife'
Parotocinclus sp. : five specimens (ZMA 121.263) 28.5 to 32. 4. SL 'clear fast moving stream near Recife' Pernambuco, Brazil, 9 1994, D Byron. Hypostominae sp. 13 specimens (ZMA 121.264) not measured, other data as 121 263.

In September 1994 we received two species originating from the same place, the area around Recife, in the North East of Brazil. At first they resembled both species from Quebrangulo (see above) but closer comparisons showed that we were dealing with a different species (see table above)

Not only the outward appearance but also the behavior resembled the two species of Quebrangulo. Admittedly, there are great differences in coloring and with Hypostominae sp, 'Recife' the distance between the eyes is noticeably smaller than in Hypostominae sp, 'Quebrangulo'.

Also both species are well suited as Aquarium fish, in so far as that can be said after a short time thus far. Hypostominae sp. 'Recife' behave territorially amongst themselves. They lie on the bed in the place where the water is flowing fastest and try to push each other away when food swirls by. However, these fish do not fight against each other, which, we know, sometimes happens with the larger species of the genus.

In Finishing
All of the Parotocinclus species presented here and both the Hypostominae are definitely interesting subjects for rearing in the Aquarium and committed fishkeepers' should succeed in breeding. Most of all, the Hypostominae were a great surprise to us. It cannot yet be said with certainty that we have a new genus, since the fact that they possibly belong to the Hypostominae genus of the small species like perhaps Hemipsilichthys has not yet been checked.

Thanks
We thank Mrs. Valeria Alves for her invaluable help during the two trips to the Nordeste. For help in the field, we thank Savio Valerio and the fishers/collectors whom we do not know by name. We are indebted to Savio and Paulo Valerio for information on habitats, equally D. Byron for the collection of P. jimi and both species from Pernambuco. Isaac Isbrücker deserves our thanks for his help in classifying the fish left behind (Hypostominae). We thank in addition Waltraud and Klaus Peter Elsholz for useful information and pictures. In addition, our thanks goes to Werner Seuss for letting us have the pictures of P. haroldii. Thanks to Friedrich Bitter his help and for useful contacts in Germany.

Literature Cited

• Bilke, E. (1992):"Eichhörnchen" im Aquarium: Otocinclus notatus. DATZ 45 (10): 625-627.
• Elsholz, K.D., & W. Elsholz (1994): Zwei selten impotoerte Arten aus der Unterfamilie Hypoptopomatinae: Hypoptopoma sp. und Parotocinclus cf. cristatus. BSSW Report 6(1) 14-19.
• Elsholz, K.D., & W. Elsholz (1992): Ohrgitter und Saugwelse - Parotocinclus cf. maculicauda, ein Saugwels aus dem Tribus [sic] Otocinclini. Wels-Jahrbuch 1993: 90-93.
• Evers, H-G. (1992) Harnischwels aud der Unterfamiliae Hypoptopomatinae (DATZ) 45(10): 623-624.
• Franke, H-J. (1961): Erstzucht von Otocinclus cf. maculipinnis Regan 1912, dem Zwergsaugwels. Aquarien Terrarien 8 (3): 67-70.
• Garavello, J.C. (1977): Systematics and geographical distribution of the genus Parotocinlcus Eigenmann & Eigenmann, 1889 (Ostariophysi, Loricariidae). Arq. Zool. S. Paulo 28 (4): 1-37.
• Garavello, J.C. (1988): Three new speices fo Parotocinclus Eigenmann & Eigenmann 1889 with comment son their geographical distribution (Pisces, Loricariidae). Naturalia (S. Paulo) 13: 117-128.
• Hieronimus, H. (1992): Neuordnung der Hypoptopomatinae. (DATZ) 45 (2): 77-78.
• Lacerda, M.T.C. (1994a): Aspidoras im Nordeste - Himmel und Hölle Brasiliens (Teil 2). Aquarisktik Aktuell 2(3): 22-23.
• Matsuzaka, M., & N. Miyake (1991): Catfishes like withered twigs. Aqua Magazine 11: 16-24.
• Morris, J.T. (1985): Observations on the spawning and raising of a member of the genus Parotocinclus Eigenmann & Eigenmann 1889. Catfish Assoc. of Great Britain 43:3-7.
• Ribeiro, P.M. (1939): Um novo Parotocinclus do nordeste Brasileiro. Bol. Biol. S. Paulo, 4: 364-366.
• Sands, D.D. (1984): Catfishes of the World (Vol. IV): Loricariidae, Aspredinidae & Doradidae. Dunure.
• Schaefer, S.A. (1988): A new species of the loricariid genus Parotocinclus from Souther Venezuela (Pisces: Siluroidei). Copeia: 182-188.
• Schaefer, S.A. (1991): Phylogenetic analysis of the loricariid sub-family Hypoptopomatinae (Pisces: Siluroidei: Loricariidae). Zool. J. Linn. Soc. 102: 1-41.
• Schaefer, S.A. & Provenanzo, F.(1993): The Guyana sheild Parotocinclus: Systematics, biogeopgrpahy, and description of a new Venezuelan species (Siluroidei: Loricariidae). Ichthyol. Explor. Freshwaters 4(1): 39-56.
• Schaefer, S.A. & Ferraris, C.J. (1985): A new species of Parotocinclus (Pisces: Loricariidae) from Guyana. Proc. Biol. Soc. Wash. 98: 341-346.
• Schraml, E. (1994) "Neue" Harnischwelse aus Brasilien. Das Aquariun 299: 12-15.
• Wendenburgh, H. (1993): Otocinclus cf. notatus, klien und empfehlenswert. Welsjahrbuch 1994: 83-85.

There is further information on this species on the Cat-eLog page.

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