Bijdragen tot de Dierkunde, 54 (2): 163-168—1984

Pyxiloricaria menezesi, a new and species of

mailed from Rio Miranda and Rio Cuiabá, Brazil

(Pisces, Siluriformes, )

by

Isbrücker H. I.J.H. & Nijssen

Institute of Taxonomie Zoology, University of Amsterdam,

P.O. Box 20125, 1000 HC Amsterdam, The Netherlands

Summary Financial for the visit Brazil support to (January 1983)

was given to the first author by the Treub Society for menezesi is described and il- Pyxiloricaria n. gen., n. sp., Tropical Research (Utrecht), the Artis Fund lustrated from Rio Miranda (Est. Mato Grosso do Sul) (Amsterdam), and the Royal Academy of Sciences of the and from Rio Cuiabá (Est. Mato Grosso), Brazil. It is Netherlands (Amsterdam). assigned to the subtribe Planiloricariina of the tribe

Loricariini, subfamily . A comparison is made

with sympatric Pseudohemiodon cf. laticeps (Regan, 1904).

Pyxiloricaria n. gen. Résumé

— menezesi donne illustrée Type-species. Pyxiloricaria n. sp. On une description de Pyxiloricaria menezesi

du Rio Miranda Mato Grosso do n. gen., n. sp., (Est. Sul)

et du Rio Cuiabá (Est. Mato Grosso), Brésil. La nouvelle Etymology. — From the Latin pyxis meaning espèce appartient à la sous-tribu Planiloricariina (tribu box (an allusion to the distinctive body shape, sous-famille On la Loricariini, Loricariinae). compare which is trapezoid in a transverse section along avec Pseudohemiodon cf. laticeps (Regan, 1904), espèce sym- the coalescing lateral and from patrique avec celle nouvelle. body scutes), of the , type-genus family Loricariidae.

INTRODUCTION Pyxiloricaria is assigned to the subtribe

Planiloricariina, tribe Loricariini of the sub-

While visiting the Museu de Zoologia da family Loricariinae (cf. Martin Salazar et al.,

Universidade de Sào Paulo (MZUSP) and the 1982), hitherto comprising the genera

Universidade Federai de Sào Carlos Pseudohemiodon Bleeker, 1862, Planiloricaria

Estado de Isbriicker (UFSCAR), Sào Paulo, Brazil, the Isbrücker, 1971, Rhadinoloricaria &

first author encountered undescribed Crossoloricaria an species Nijssen, 1974, Isbriicker, 1979, of the subfamily Loricariinae. It is herein and Dentectus Martin Salazar, Isbrücker &

described and 1982. as a new genus species, Pyxi- Nijssen,

loricaria menezesi. The shows It differs from all these well genus a superficial genera (as as

similarity to Pseudohemiodon Bleeker, 1862, from all other genera of the subfamily

with four the of which, together other genera has been Loricariinae) by peculiar shape head,

assigned to the subtribe Planiloricariina, tribe body and fins (figs. 1-4). Pyxiloricaria has large,

Loricariini (Martin Salazar et al., 1982). broad pectoral fins (pectoral fin spine 3.9-4.5

times in standard length, rarely 4.5, usually

We C. are grateful to Dr. J. Garavello (UFSCAR), who 5.0-6.6 in other and Planiloricariina), a low in the and of participated collecting holotype a paratype number of lateral body scutes (29-30, against Pyxiloricaria menezesi, and to Dr. H. A. Britski (MZUSP) 31-40 in the other of for the loan of'the material. Mr. A. der Laan of the genera Planiloricariina). L. van

Fin counts: dorsal I,6,i; anal I,4,i; Zoölogisch Museum, Amsterdam (ZMA) made the ray pec- photographs. toral 1,6; pelvic 1,5; caudal 1,10,1.

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1. menezesi in dorsal view. Fig. Pyxiloricaria n. gen., n. sp., holotype

Further in the 56°19'W), coll. J. C. Garavello and characters are given descrip- (20°10'S party (Eq. Iet. DCB-UFSCAR), 8/22-XI-1981 ; MZUSP tion of the single species included in Pyxi- paratype, 24860, standard length 105.3 mm, Brazil, Est. Mato loricaria: Grosso, Rio Cuiabâ, at ca. 3 km from Santo Antonio

do Leverger (15°52'S 56°05'W), coll. CEPIPAM, menezesi Pyxiloricaria n. sp. 28-VIII-1976.

(Figs. 1-4; table I)

Etymology. — Named in honour of Dr. Naer- Material. — Holotype, MZUSP 26800, standard length cio A. Menezes, MZUSP, in recognition of his 136 mm; paratype, ZMA 107.890, standard length 90.1 and the first Est. Mato Grosso friendly support hospitality during mm, Brazil, do Sul, "Lagoas marginais da rodovia Transpantaneira, municìpio de Miranda" author's stay in Brazil.

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Description. — Morphometric and meristic TABLE I

data (taken according to the methods described Morphometric and meristic data of Pyxiloricaria menezesi n. Isbrücker 1978: by & Nijssen, 180-182) are data of in gen., n. sp.: (A), holotype mm; A, holotype; B, in table I. 1-4 illustrate the 107.890. given Figs. paratype MZUSP 24860; C, paratype ZMA

Standard total in In columns holotype. length through length mm. head lower caudal Preanal absent. There is A-C, length through spine length are Holotype: plate a ratios of standard snout expressed as length, length double of narrow median, mostly row irregular through width caudal peduncle are expressed as ratios of

scutelets anterior to the anus polygonal (which head length.

is surrounded by a small, triangular naked

area). These scutelets reach similar small specimens (A) A B C the scutelets within area between the posterior Standard length 136.0 136.0 105.3 90.1 three thoracic scutes. Anterior to these axial length 153.8 153.8 118.6 102.5 scutelets, the abdomen is partially covered with total length >228.6 >228.6 230.7 201.5 scutelets, isolated naked skin from the by head length 30.4 4.5 4.5 4.2 thoracic the scutelets continue between scutes; predorsal length 45.6 3.0 3.1 2.9

1.8 1.8 1.9 the pectoral fin origin as shown in fig. 4. postdorsal length 75.3 60.1 2.3 2.2 2.3 of postanal length Ventral surface head naked, except for a dorsal spine length 28.3 4.8 4.9 <5.2 marginal series of somewhat rectangular first dorsal ray dermal ossifications. A transverse, large, fleshy length 26.7 5.1 5.2 4.5 wrinkled from the anterior flap originates anal spine length 21.8 6.2 6.8 5.3

of the 30.4 4.5 — 3.9 margin branchiostegal membrane, cover- pectoral spine length pelvic spine length 18.8 7.2 6.4 6.6 ing about half of this membrane. caudal upper spine naked Upper lip preceded by a area, continu- length >92.6 <1.5 0.8 0.8 into the notched ventrorostral ing anteriorly lower caudal spine six ossification. Upper lip narrow, with or seven length 23.4 5.8 <5.8 <7.2

17.2 simple barbels along or near the edge at either snout length 1.8 1.8 1.8 ventrorostral length 2.8 10.9 18.0 13.4 side. Premaxillae surrounded by three series of lower lip 6.9 4.4 4.4 4.9 barbels minute slender, simple (ignoring a pro- maxillary barbel 11.3 2.7 2.7 2.2 tuberance at one a trifid barbel), longitudinal thoracic length 27.7 1.1 1.1 1.2 barbel the of the and at symphysis jaws, a abdominal length 25.9 1.2 1.3 1.4

maximum orbital dia- transverse series of three barbels at either side.

meter 6.5 4.7 4.4 4.9 Maxillary barbel free from margin of snout, interorbital width 5.2 5.9 6.5 6.1 embedded into The barbel has six a groove. cleithral width 32.4 0.9 1.0 1.0 subbarbels. for the barbels, the ventral Except supracleithral width 19.7 1.5 1.6 1.6 surface of the the upper lip and connecting area head width 29.8 1.0 1.0 1.0 towards the maxillary barbel origin is smooth. head depth 11.7 2.6 2.7 2.5

body depth at dorsal 13.3 2.3 2.4 2.5 Lower lip close-set with short, smooth barbels, body width at dorsal 22.6 1.4 1.4 1.6 decreasing in length towards the posterior body width at anal 18.0 1.7 1.7 1.8 which itself is almost smooth, ir- margin, depth caudal peduncle 2.5 12.2 13.0 13.4 regular, bearing a few minute barblets only. width caudal peduncle 4.0 7.6 6.9 6.9

lateral — 30/30 30/29 Mandibulae surrounded by few, slender scutes 29/29

scutes — 20/20 17/17 18/18 barblets and wide naked in front of coalescing by a area;

thoracic scutes — 7/7 7/7 7/6 the the lower numerous simple barbels on lip premaxillary teeth — 2/3 3?/3? 2?/2 are a few bifid and trifid barbels. dentary teeth — 2/3 ?/? 3/2 Pectoral fin spine rather broad, dorsally and

flattened. Pectoral fin ventrally rays proximally broad, the third ray being the broadest at its tip Tip of snout covered with odontodes. with distally eight branches. Thoracic scutes touching the inner pectoral fin

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2. menezesi n. in lateral view. Fig. Pyxiloricaria gen., n. sp., holotype

3. menezesi in ventral view. Fig. Pyxiloricaria n. gen., n. sp., holotype Downloaded from Brill.com09/29/2021 07:52:33PM via free access - 1984 BIJDRAGEN TOT DE DIERKUNDE, 54 (2) 167

4. menezesi detail of head of in dorsal and ventral view. Fig. Pyxiloricaria n. gen., n. sp., holotype

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with horizontal devoid of Both resemble each other ray a narrow strip species superficially.

odontodes the At odontodes. There are no on this point we think it to be sufficient to men-

scutes covered by the last pelvic fin ray and tion only the most obvious differences: Pyxi-

fin. has col- along the base of the anal loricaria menezesi a slightly lighter ground

Pectoral visible. canal head in pore not Sensory our, a more acute, triangular profile

dorsal and broader system inconspicuous. view, longer pectoral fins,

different colour and Orbital rim oval, with a continuous small larger eyes, a pattern, par-

the in anterior notch, a narrow lateroventral naked ticularly coalescing scutes transverse sec-

and tion in vertical The abdominal strip, a larger posterior notch. a more position.

Teeth with scutelets in the Pseudohemiodon of hard to observe: small, simple, a specimens

broad size are different in size and rounded crown. comparable pat-

tern, covering most of the belly. The

Colour in alcohol — Ground colour Pseudohemiodon have broader (figs. 1-4). specimens a

Dorsum and sides with faint ossified ventral and beige. greyish head margin, a conspicuous

shown in the illustrations. brown pigment, as ventrorostral extension. Moreover, the

Pseudohemiodon specimens have different lips the Paratypes: Essentially as holotype, having (lower lip papillate, without barbels; lip with less and smaller abdominal scutelets. numerous the numerous long, papillate barbels along As shown in table I, some morphometric posterior margin), and lack the fleshy flap characters different are quite (e.g., length first covering the branchiostegal membrane in Pyxi- dorsal fin anal fin spine length, pectoral fin ray, loricaria menezesi. Such is known be a flap not to fin maximum spine length, pelvic spine length, in other loricariid. present any orbital diameter, and interorbital width). With

three — from two — only specimens localities REFERENCES

available, it is difficult to explain these dif- ISBRÜCKER, I. J. H. & H. NIJSSEN, 1978. Two new species ferences. and of mailed of a new genus neotropical

the subfamily Loricariinae Swainson, 1838 (Pisces,

— menezesi col- Comparison. Pyxiloricaria was Siluriformes, Loricariidae). Beaufortia, 27 (339):

177-206. lected at its type-locality together with 98

MARTIN SALAZAR, F. J., I. J. H. ISBRÜCKER & H. NIJSSEN, specimens of a Pseudohemiodon species, which we 1982. Dentectus and barbarmatus, a new genus P. tentatively identify as laticeps (Regan, 1904) species of mailed catfish from the Orinoco Basin of in MZUSP 26802, six in ZMA (eight specimens Venezuela (Pisces, Siluriformes, Loricariidae). the in 107.889, remaining ones UFSCAR). Beaufortia, 32 (8): 125-137.

Received: 17 July 1984

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