Bijdragen tot de Dierkunde, 55 (2): 242-248 — 1985

Lasiancistrus scolymus, a new species of mailed from

Rio Aripuanã, Est. Mato Grosso do Sul, Brazil (Pisces, Siluriformes, )

by

H. Nijssen & I.J.H. Isbrücker

Institute of Taxonomic Zoology, University of Amsterdam, P.O. Box 20125, 1000 HC Amsterdam, The Netherlands

Abstract holotypes and feel confident that they represent

two distinct Lasiancistrus is described and species. scolymus n. sp. illustrated,

the from Rio Rio based upon holotype Aripuanã, We Dr. H. A. Britski and Madeira Est. Mato do Brazil. It is are grateful to (MZUSP), to system, Grosso Sul, Mr. G. J. Howes (British Museum (Natural History), compared with Lasiancistrus heteracanthus (Günther, 1869),

London, for access the material in their care. of the Lasiancistrus 1904. BMNH) to type-species Regan, Taxonomische Mr. L. A. van der Laan (Instituut voor

Zoologie (Zoologisch Museum), Amsterdam, ZMA) Résumé made the photographs.

Lasiancistrus scolymus n. est décrit et illustré, cette des- Financial for the visit Brazil the sp. support to was given to basée Rio cription étant sur l’holotype du Aripuanã, second author by the Treub Society for Tropical Research bassin du Rio Madeira, État Mato Grosso do Brésil. Sul, (Utrecht), the Artis Fund (Amsterdam), and by the Royal

La nouvelle est Lasiancistrus espèce comparée avec Academy of Sciences of the Netherlands (Amsterdam). heteracanthus du Lasian- (Günther, 1869), espèce-type genre cistrus Regan, 1904.

Lasiancistrus scolymus n. sp.

(Figs. 1-3; table I-A)

INTRODUCTION Material. — Holotype, MZUSP 26809, probably a nup-

143.6 Est. Mato tial male, standard length mm, Brazil,

The holotype and single known specimen of the Grosso do Sul, Rio Aripuana, Humboldt (10°10'S

describe here 59°27'W), Rio Madeira system, coll. J. G. Da Silva, species we as Lasiancistrus scolymus 16-X-1976. n. sp. was found in the ichthyological collection of the Museu de da Universidade de Zoologia — Latin kind Etymology. From the scolymus, a Sao Paulo visit of the (MZUSP) during a of the of different thistle; alluding to presence second author in 1983. January and head. sharp odontodes on the sides of snout

According to Howes (1983), Lasiancistrus

Regan, 1904, is a genus of the subfamily Description. — Morphometric data (taken

Chaetostomatinae (incorrectly spelled Chaeto- according to the methods described by Heit- stominae inclusion 1983: in by Howes, 1983). With the mans et al., 34-35, fig. 1) are given

of table I. 1-3 illustrate the of the new species, Lasiancistrus consists 24 Figs. holotype.

with of about species (cf. Isbriicker, 1980; Heitmans et al., Interoperculum a clump 25

several of well known. 1983), which are not prominent evertible odontodes, anteriorly

After in a comparison with various species (either about 3 mm long, increasing gradually size from specimens or from data in literature), La- posteriorly, the longest being about 15 mm. siancistrus The odontodes embedded in scolymus appears to us to be most are proximally a closely related with the type-species of the fleshy shaft, of which the thickness (on the

L. heteracanthus which odontode the distal end of the genus, (Giinther, 1869), longest at shaft)

the We have is 0.9 odontodes is known from holotype only. mm. These evertible are made a direct comparison between both whitish, except for their tips, which are bright 55 - 1985 243 BIJDRAGEN TOT DE DIERKUNDE, (2)

in dorsal view. Fig. 1. Lasiancistrus scolymus n. sp., holotype

in ventral view. Fig. 2. Lasiancistrus scolymus n. sp., holotype - SCOLYMUS N. SP. 244 H. NIJSSEN & I. J. H. ISBRUCKER LASIANCISTRUS

The Two the anal fin yellow. tips are sharply curved toward the scutes are present along

eleven between the anal fin and the anterior axis of the head, and acute distally. base, and

fin The clump of evertible odontodes is bordered procurrent caudal spinule. These ventral

(and partly mixed with) dorsally, anteriorly and scutes are also flattened. Posteriorly they are

series of broader than the dorsal sides of the caudal ventrally by a extremely thin, often more feeble ventrolateral keel very long (stiff, hair-like) odontodes, up to peduncle, forming a on

measured from the the last five behind the head are five about 12.5 mm long as scutes. Just

distal end of the fleshy shaft. These "hairs" scutes at either side in transverse series.

Dorsal fin anal fin fin have various distal positions. Some curve faint- I, 6, i; I, 4, i; pectoral

fin caudal fin I. Five ly sideward, others backward, and still others I, 6; pelvic I, 5; I, 14, pro-

caudal fin in front bend forward; some are straight. Like the ever- current spinules of the upper

tible odontodes, the "hairs" are whitish and lobe, one in front of the lower lobe.

Caudal fin the lower have minute, acute, yellow-coloured tips which slightly emarginate,

be curved not. lobe than the may or being longer upper.

shorter hair- Head and in front of the Similar, although considerably snout eyes rough,

like odontodes the sides of where are present on the especially along the snout margin,

anterior the leav- ossifications extend towards the snout to interopercular area, ventrally nar-

ing a broad frontal area devoid of them. The row dorsal side of the upper lip.

longest of these fragile odontodes are about 5.5 Cleithrum likewise rough, the remainder of

mm. The opercular margin is provided with the head being smooth because of the minute

twelve (at the right side, because of damage odontodes. Sutures of most ossifications of the

most are lost at the left side) thin but promi- head are faintly visible, except for those on and

with nent, erect or oblique odontodes, largest of along the snout. Body scutes longitudinal

which 2.8 series measures mm. of prominent odontodes, those along their

Lateral body scutes 25, including a margins larger than the others. Dorsum of first

triangular scutelet on the caudal fin base. three pectoral fin rays and of first four pelvic fin

scutelets the with odontodes. Small, triangular on caudal fin rays prominent

base 7 (left side), 8 (right side) in vertical series. No continuous longitudinal series of promi-

Predorsal scutelets between the odontodes the 5, supraoc- nent on body scutes.

and the fin rim raised. cipital process procurrent dorsal Supraorbital hardly Supraoc-

one at either side of the with a spinule: (a) supraoc- cipital posteriorly transversely straight

median broad cipital process, (b) two large, scutes and process.

median Abdomen line (with a faint suture, anteriorly reaching entirely naked. Lateral hardly

the median supraoccipital process), (c) a pair of visible.

more or less scutes faint Dorsum of its triangular (with a me- upper lip very narrow, naked,

dian and smooth. side of this suture), (d) a narrow, curved predor- margin Ventral lip narrow,

sal scutelet in front of leav- the procurrent predorsal with a transverse series of small papillae,

smooth in teeth. The spinule. This scutelet reaches to the first of six ing a margin front of the

scutes the dorsal fin followed of the continues without along base, by papillate part upper lip

seven scutes between the dorsal fin and the interruption onto the lower lip. The lower lip is

fin adipose spine (which is preceded by one papillate (except for its posterior margin, which

is and for the base azygous scutelet, having a sharp posteromedial smooth, except a strip near

the fin the elevation), one scute along adipose of the teeth); the larger papillae are those on

middle of the the At spine, three scutes along the adipose fin mem- lip, beyond teeth. either

and brane, two scutes between this membrane side there is a small, smooth, triangular max-

and the caudal barbel. first procurrent fin spinule. illary

These —between dorsal fin and the The is about 11 with scutes spine premaxilla mm, caudal fin base— are dorsally flattened. numerous small and slender teeth. The teeth BIJDRAGEN TOT DE DIERKUNDE, 55 (2) - 1985 245

3. Lasiancistrus head of in lateral and ventral view. Fig. scolymus n. sp., holotype dorsal, 246 H. NIJSSEN & I. J. H. ISBRUCKER - LASIANCISTRUS SCOLYMUS N. SP.

sometimes dou- are arranged into an irregular, ble which is difficult to count row, accurately.

The of the teeth is crown premaxillary sharply

with bent inwards. The teeth are bifid, a larger,

and truncate inner lobe a smaller, triangular outer lobe.

and has The mandible is about 10 mm

in numerous teeth, like those the premaxilla.

The mandibular teeth have a large, elongate

lobe and (rectangular to acute) inner a smaller, triangular outer lobe.

Colour in alcohol. — Ground colour of

of of naked ventral parts reddish tan, lips and ventral body scutes yellowish and greyish tan,

minute respectively. Abdomenwith numerous, whitish, ill-defined markings.

Sides and dorsum of head and body, and the

brownish without fins are grey, markings.

Comparison. — See Lasiancistrus heteracanthus, below.

Lasiancistrus heteracanthus (Günther, 1869)

(Fig. 4; table I-B)

Chaetostomus heteracanthus Gunther, 1869: 425-426, figs. 3-4

(original description; type-locality: "Upper Amazons" and "Peruvian Amazons"; holotype).

Material. — Holotype examined, BMNH 1869.5.21:3,

standard 153 probably a nuptial male, length mm, Peru,

Upper Amazon, coll. E. Bartlett.

Fig. 4. Lasiancistrus heteracanthus (Günther, 1869), Comparison with Lasiancistrus scolymus.- reproduction of Günther’s original illustrations of the data in table I. 4 Morphometric are given Fig. holotype. is a reproduction of Gunther's (1869, figs. 3-4) original illustrations.

Gunther (1869: 426) stated in italics: "In- Lateral body scutes 26 (left side), 27 (right

scutelets the teroperculum with two kinds of spines, there side). Small, triangular on caudal

of twelve slender but stiff in being a group about fin base 8 (both sides) vertical series. Predor- and slightly hooked spines surroundedby a ring sal scutes 4. Two scutes along the adipose fin of long setiform spines..." membrane, and five between this membrane

and caudal fin Interopercular evertible, spike-like odon- the anterior procurrent spinule.

Number of in todes 7 mm long anteriorly, 17.6 mm posterior- scutes otherwise as Lasiancistrus ly; length of interopercular evertible hair-like scolymus.

about of odontodes up to 25 mm. Margin snout Fourth predorsal scute very small, crescent- in front of the hair-like odontodes, and anterior shaped, just reaching anterior margin of first surface of interoperculum, rough because of the scute along dorsal fin base. Mediodorsal scutes

of odontodes. flattened. presence prominent not distinctly - 1985 247 BIJDRAGEN TOT DE DIERKUNDE, 55 (2)

TABLE I

data of the ofLasiancistrus and those of L. heteracanthus Morphometric holotype scolymus n. sp. (Günther, 1869), respect-

= ratios of standard A’-B’ = ratios of head ively. (A-B) = data in mm; A-B length; length.

specimen (A) (B) A B A' B'

mature male + +

standard length 143.6 153.0 143.6 153.0 143.6 153.0

axial length 170.2 — — — — —

— — — — total length 186.5 —

head length 51.7 59.0 2.8 2.6 — —

predorsal length 62.7 70.5 2.3 2.2 0.8 0.8

postdorsal length 50.8 52.2 2.8 2.9 1.0 1.1

postanal length 41.6 40.1 3.5 3.8 1.2 1.5 dorsal fin base 29.5 33.5 4.9 4.6 1.8 1.8

interdorsal length 31.1 30.0 4.6 5.1 1.7 2.0

dorsal spine length >31.2 45.1 <4.6 3.4 <1.7 1.3

anal spine length 15.4 19.2 9.3 8.0 3.4 3.1

anal fin height 20.3 22.2 7.1 6.9 2.6 2.7

pectoral spine length >47.1 60.2 <3.1 2.5 <1.1 1.0

pelvic spine length 31.0 39.0 4.6 3.9 1.7 1.5

adipose spine length 13.1 7.6 11.0 20.1 4.0 7.8

caudal 35.8 — 4.0 — 1.4 — upper spine lower caudal spine 42.9 >35.6 3.4 <4.3 1.2 <1.7

snout length 34.0 37.8 4.2 4.1 1.5 1.6 lower lip length 7.7 9.7 18.7 15.8 6.7 6.1

maxillary barbel 2.6 2.9 55.2 52.8 19.9 20.3

16.7 19.9 6.0 7.7 maxillary barbel + lip 8.6 7.7

thoracic length 34.2 36.0 4.2 4.3 1.5 1.6 abdominal length 34.2 33.4 4.2 4.6 1.5 1.8

maximum orbital diameter 7.9 9.3 18.2 16.5 6.5 6.3

interorbital length 23.5 31.5 6.1 4.9 2.2 1.9 cleithral width 47.1 50.0 3.1 3.1 1.1 1.2

supracleithral width 42.2 48.2 3.4 3.2 1.2 1.2 head depth 21.9 26.1 6.6 5.9 2.4 2.3 body depth at dorsal 21.1 25.5 6.8 6.0 2.5 2.3 body width at dorsal 41.5 41.6 3.5 3.7 1.3 1.4 body width at anal 26.7 24.7 5.4 6.2 1.9 2.4 depth caudal peduncle 15.5 15.9 9.3 9.6 3.3 3.7 width caudal peduncle 7.9 6.6 18.2 23.2 6.5 8.9

Dorsal fin anal fin formulae of Interorbital I, 7; I, 5; pec- through supraoccipital area

caudal in L. rather toral, pelvic, and fins as scolymus. smooth, cleithrum slightly rougher.

Distal ends of caudal fin and broken side. spines rays Supracleithral margin damaged at right off. Pectoral fin with short, thorn-like odontodes.

with about six Anterior halfof dorsum of first fin Operculum very small, oval, pectoral ray

odontodes which with odontodes. conspicuous curve backward. prominent

Area around operculum up to orbital rim, and Abdomen with numerous minute dermal

reaching to interopercular margin, covered ossifications bearing odontodes, the ossifica- with isolated dermal ossifications embedded in tions being widely scattered at the height of the

skin. fin Supraorbital margin hardly raised. pelvic bases, gradually becoming more 248 - H. NIJSSEN & I. J. H. ISBRUCKER LASIANCISTRUS SCOLYMUS N. SP.

is not numerous anteriorly, reaching to the the last ray of dorsal- and anal fin split,

whereas these the in anteroventral margin of the cleithrum. rays are split to base L.

Dorsum of almost upper lip rough, complete- scolymus.

for its covered with L. heteracanthus has dermal ossifications ly (viz., except margin) (c) on

odontodes. the which abdomen ossifications bearing conspicuous abdomen, are absent on the

with notch. Orbital rim a small posterior of L. scolymus. The respective holotypes differ

mandible 8 9.4 in standard The premaxilla as well as the are only mm length.

Teeth and The size and number of odon- mm. numerous, long very slender; interopercular in than todes different in more one row, being difficult to count is strikingly both species.

Since each is known from accurately. The crown of the inner tooth lobe is species a single

dif- quite large and either truncate or acute distally, specimen only, it is uncertain whether these

of the lobe is much due the whereas the crown outer ferences are to stage of development of

and smaller triangular. a secondary sexual character or indicative of a

species distinction.

— The is Colour. holotype now completely faded. Gunther (1869: 426) described the col-

"Uniform each dorsal our as: greyish; scute

REFERENCES lighter in the centre." Regan (1904: 237)

the colour of the described pattern same GUNTHER, A. [C. L. G.], 1869. Descriptions of some blackish specimen as follows: "Olivaceous; a species of fishes from the Peruvian Amazons. Proc. spot at the base of the first dorsal ray." zool. Soc. London, 1869: 423-429.

HEITMANS, W. R. B., H. NIJSSEN & I. J. H. ISBRUCKER, Main differences between Lasiancistrus 1983. The mailed catfish Lasiancistrus genus Regan, heteracanthus and L. - scolymus. 1904, from French Guiana and Surinam, with

characters head of (a) Morphometric (table I): descriptions two new species (Pisces, Siluriformes, length, postanal length, interdorsal length, Loricariidae). Bijdr. Dierk., 53 (1): 33-48. HOWES, G. J., 1983. The cranial muscles of loricarioid dorsal-, anal-, pelvic-, and adipose fin spine their and value taxonomic , homologies as length, abdominal length, orbital diameter, in- characters (Teleostei: Siluroidei). Bull. Br. Mus. terorbital width, headdepth, body depth at dor- nat. Hist. (Zool.), 45 (6): 309-345. sal fin width anal fin and origin, body at origin, ISBRUCKER, I. J. H., 1980. Classification and catalogue of depth and width of caudal peduncle. the mailed Loricariidae (Pisces, Siluriformes).

Verslagen en technische Gegevens, Inst, taxon. (b) Meristic characters: number of lateral body Zool. (Zool. Mus.), Univ. Amsterdam, 22: 1-181. scutes, predorsal scutes, scutes between adipose REGAN, C. T., 1904. A monograph of the fishes of the fin spine and origin of caudal fin, and number family Loricariidae. Trans, zool. Soc. London, 17 of odontodes. In L. heteracanthus interopercular (3): 191-350, pis. IX-XXI.

Received: 14 November 1984