A Comparative Study of the Feeding Mechanisms of

some AFrican Cyprinidae (Pisces, Cypriniformes)

by

H. Matthes

Zoological Laboratory, University of Amsterdam

with 12 plates

there voluminous litera- Vincig., Xenobarhus Although exists an extremely namely: Phreatichthys 1924,

Caecobarbus ture on Cyprinid fishes and the morphology and phy- Norman, 1923, and Blgr., 1921, only

of has the last has had with siology some species been intensively studied its biology investigated, though

little known about reference its habits and by various authors, very is yet no special to feeding morpho- derived feeding mechanisms and their functioning in most logy (Heuts, 1951), and all are directly from members of this family. Barbus, from which they apparently differ little. A-

So far ￿ non-African as known, only some European species mongst species, Cyprinus carpio Linn., and Rasbora e-g- Cyprinus carpio, Carassius auratus, iRutihis ruti- 1758, Leuciscus cephalus (Linn., 1758)

Gobio ￿ and also for lus, gobio one Asian (Labeo rohita), one sp. were examined, comparative purposes. African (Labeo horie) have been investigated thor- The bulk of the ecological data stems from personal

in in in oughly as regards their morphology relation to observations on live fish, either nature or aqua-

their habits. of well from feeding Moreover ,the ecology most ria, as as numerous gut content analyses. African culled species is only scantily known. Complementary information was from various This of the mechanisms study feeding of one or sources, e.g. Girgis (1952), Greenwood (1958),

of of the African Fryer Daget Poll more typical representatives most (1959), (1954), (1953; 1959),

genera, will, I hope, serve to clarify some interesting Boulenger (1901; 1907), etc. The osteology and

and lead lines of field musculature of the mouth and studied points to new research in a pharynx were

where so much is still left to be done. from mounted skeletons, Alizarin preparations (for

small species) and from careful dissections (also under ACKNOWLEDGEMENTS the microscope).

For material of African A series of bones from both Afri- generous help in providing large pharyngeal well facilities and also and Cyprinidae as as working at the "Mus￿e can European species was examined

Royal d'Afrique Centrale" (Tervuren), I'm deeply in- compared.

The nomenclature depted to Prof. M. Poll, conservator of vertebrates followed is essentially the same

there. thanks also for that used My the help received from Prof. as by Gregory (1933) and Ramaswami

Dr. E. under whose this work for the bones and Edge for J. Slijper, guidance (1955) by worth (1935)

carried and his the muscles. the was out, to assistants at the "Zo~lo- Owing to fact that muscle nomen-

Amsterdam I'm also clature found to be rather table of the gisch Laboratorium", University. was confused, a thankful cranial muscles very to Prof. Dr. H. Engel, director of the and their main function has been

drawn "Zoologisch Museum" (Amsterdam), who kindly al- up (Table I) enabling rapid comparison of the lowed the full of the of the different used authors. me use library Ichthyolo- names by various No attempt

gy section. at establishing synonymies for these different terms

made. The used in was names this paper are the

MATERIALS AND METHODS which ones appear most appropriate, taking into ac- the Species belonging to following genera were taken count not only the muscle function but also its onto-

under consideration: geny.

Labeo, Garra, Barbus, Varicorhinus, Barbopsis, In order to study the finer structure of the inner

Coptostomabarb us, Leptocypris, Barilius, Engraulicy- mouth and pharyngeal linings, histological sections of

head pris, Chelaethiops. the region of Barbus pleuropholis and of the

Of the three other African not studied lamellar genera here, vomero-palatine organ and pharyngeal pad

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Labeo lineatus made. the maxillaries excluded from ("palatal organ") of were Stain- only, being completely

done with and the of the mouth. and barbels various- ing was mostly Azan Haematoxylin- gape Lips are absent Eosin. Numerous drawings and photographs have ly developed and may even be altogether.

all salient Paired valvular been included in order to illustrate points. nostrils, separated by a flap, are si-

tuated the the the of on snout, anterior to eye; sense

smell is known to be well developed in GENERAL INTRODUCTION extremely 1957, vol. II). The form rich and diversi- Cyprinids (Brown, Cyprinidae an extremely A membraneous valve is present along the inner fied family and its numerous species have adapted to side of the valve). A true This di- upper jaw only (maxillary a broad variety of environments. ecological remarkable devel- tongue is, with one exception, not versity is directly related to their high morphological

oped, there a more or less ,and remarkable only appearing distinctly variability many trophic specialisa- raised hump in the mouth-floor, over the glossohyal. tions illustrate the close relationship between the The inner lining of the bucco-pharyngeal cavity morphology of their feeding mechanisms and their gen-

numerous more or less mode of life. erally presents longitudinal and the be modified in be subdivided plicae palatal epithelium may Feeding in Cyprinids can into sever- several relation habit in to a particular feeding al distinct actions, i.e.: prehension, selection (filter- ways, thicken- (e.g. vomero-palatine organ). Posteriorly, a ing), mastication, deglutition and digestion. Accord- ed dorsal most of the ante- the of each studied pharyngeal pad occupies ingly, following account genus

rior a narrow has been subdivided thus: pharyngeal cavity, leaving only pas-

for water and food this sage particles; "palatal organ"

1. General characters (brief covered with diagnostic description is a stratified, strongly papillose, and/or

of the studied and references to Below submucosa genus), species plicated epithelium. this, the con-

earlier work done. elastic fibres sists largely of collagen and in a matrix

2. of the considered. Ecology species of connective tissue. The thick muscularis is com-

3. Functional of the mechan- morphology feeding posed of numerous muscle strands running in all di-

isms, subdivided into: well somewhat rections as as collagen fibres, etc. A

External features sense a) (rostrum, organs, lips, similar, but smaller and thinner, triangular ventral etc.) pad overlies the anterior pharynx floor, just in front b) of the Bucco-pharyngeal cavity, comprising: pharyngeal teeth area. Investigations by sever- i. The and buc- prehensile apparatus (mouth al authors (Al-Hussaini, 1949; Dorier & Bellon, cal cavity). 1952; Maltzan, 1935; Girgis, 1952, etc.) have shown

ii. The selective apparatus branchial that fishes cells in (palate, cyprinid possess numerous mucus

arches and anterior the well well-devel- pharynx). bucco-pharyngeal mucosa, as as

c) The which masticatory apparatus (posterior pharynx). oped taste buds, are particularly numerous in The d) digestive tract. the herbivorous species. These cells are more or less

4. Conclusions and discussion (adaptations, applica- concentrated locally, for instance: the concentrations

of buds barbels well the tion of results obtained to other fields, further taste on or lips, as as on

lines of research, etc.) palate and pharyngeal pad; and the high concentra- of tions mucus glands (goblet cells) in the posterior

In order to matters and avoid where are situated to simplify unnecessary pharynx, they ideally ensure efficient lubrication of the food. The repetition, a general introductory review is given histological in-

here, broadly along these lines, relating all character- vestigations carried out in connection with this sub-

these fish found in results those obtained these istics were to possess common. ject gave corroborating by

Hence, in the individualaccounts, only those features authors.

which The arches in they differ significantly from the overall gill are 4 in number, branchiostegal

and from other will be considered. 3, the membranes more or less ex- picture species rays gill usually tensively united to the isthmus ventrally. The devel-

and functional of the GENERAL CHARACTERS opment importance gill-rakers

In all fishes of this family the mouth is toothless and varies greatly in the different species, ranging from

the the of Barilius the generally more or less strongly protractile, impor- rudimentary stumps to highly spe-

in sieve mechanism of Labeo. Pseudo- tant modifications of the posterior pharynx being cialised intricate

direct relation to the first character. branchiae, often of the enclosed type, are usually

bordered the the of the bran- The upper jaw is by premaxillaries present, lying in antero-superior part

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chial Where in this show differ- cavity, against the posterior aspect of the upper any particular case may

these described hyomandibular. ences, are accordingly.

The 5th branchial arches are modified into more

less falciform MUSCULATURE or or triangular, paired pharyngeal

bones, lying parallel and internal to the 4th branchial In the following table, the cranial muscles and their

of function well the different arches and bearing a variable number teeth inter- principal as as names

the them authors have been included. nally, arranged in 1 to 3 rows. Rostrally, antero- given by various often ventral processes of the pharyngeal bones unite in a Since their origins and points of insertion vary

and forwards different these will be described the ligamentous symphysis are prolonged in species, in

less if the individual by a more or strongly developed cartilage ex- next section and, necessary, in ac- identical tending to the posterior basibranchials; the postero- counts. All these muscles are essentially in also bend outwards and the the different but their ventral processes laterally cyprinid genera, development,

dorsal reach into the relative and consider- (ascending) ones up subtemporal positions importance may vaiy

fossae. The teeth teeth muscles be absent in pharyngeal are true (Hoppe, ably. Also, some secondary may

muscle the bucco- 1894) and their form varies in close correlation with some species. Striate occurs in

habit, often and in the anterior the feeding consequently being very spe- pharyngeal cavity, oesophagus

cialised of of the intestine well in the of (Heckel, 1843). They are composed an portion as (partly); rest

enamel-like the smooth muscle is Muscles crown, dentine, a pulp cavity containing gut only present.

the nerves and blood vessels, which whose function has but little or no incidence on feed- pulp pass further attended here. through the spongy, alveolar lateral surface of the ing movements shall not be to

hollow Further detailed information the cranial muscles pharyngeal bones, and the root. on

The teeth of fishes be culled from Takahasi are regularly replaced by new ones (po- Cyprinoid can

lyphyodont dentition), which are developed in the (1925).

between and the functional mucous coat alongside

and later become attached root to the ones by a MECHANISM OF MOUTH PROTRUSION, DEGLU- underlying bony covering, just before becoming func- TITION AND MASTICATION tional, the old teeth falling out. The mouth is opened through the action of the long-

work sclerous attached throat the They against a plate to a gitudinal muscles, namely, geniohyoidens

ventralprocess of the basi-occipital which also extends and the posterior sternohyoideus, which pull down

anterior the lower and the buccal backwards under the vertebrae and repre- jaw simultaneously dilate

the bones These muscles from the sents upper pharyngeal (pharyngeal proc- cavity. originate respectively ess). The short muscular oesophagus leads directly anterior extremities of the ceratohyal and le & 2e

the from which and from the dorso-rostrad into intestine, it is separated by an branchiostegals, anterior

there stomach surface of the cleithrum for- oesophageal-intestinal sphincter; is no (and coracoid); they run

wards present and no pyloric caecae are developed, the to insert respectively on the posterior edge of digestive tract being thus greatly simplified. How- the anterior dentary branches and the dorsal surface

intestine ever, the anterior usually presents a swollen of the urohyal and/or hypohyalia. wider which "stomach" of mouth the portion constitutes a sorts. When the opens, ascending coronoid

The varies in direct correlation nutri- the forward, gut length to process of dentary/angular swings push-

tion, being, for instance, extremely long in herbivo- ing the caudal extremity of the maxillary￿to which it The and the rous species. histology physiology of is connected through a ligament￿forward. The pre-

of has been which the digestive tract Cyprinids already inten- maxillary, is joined to maxillary through a

studied various authors and sively by (e.g. Curry, 1939; ligament posteriorly, antero-medially via a liga-

Maltzan, 1935; McVay & Kaan, 1940; Pictet, ment and the rostral bone to the vomero-mesethmoid

1909; Sarbahi, 1940; etc.). fork, is also carried forward. Wider opening of the mouth furthermore pulls the maxillary and premaxil-

OSTEOLOGY of the lary downwards, through action coronoid proc-

of the osteolo- and the membraneous between the For a comprehensive, succinct account ess ligament

gy of the cyprinid skull and the dynamics of its va- posterior extremities of the maxillary/premaxillary

The and the rious parts, one can consult Gregory (1933). dentary, at corner of the mouth. The rocking

mechanism of related to action of the maxillaries the mouth and general moving bony parts as opens closes achieved feeding movements is explained further on (see: Me- is through the rolling action of the

chanisms of mouth protrusion and mastication). maxillary condyles which articulate dorso-posteriorly

Downloaded from Brill.com10/05/2021 03:05:48PM via free access Table I. The cranial muscles of Cyprinidae, their function am

Muscle Function

Edgeworth Takahasi (& Al-Hussaini)

Adductor mandibulae closing of mouth adductor mandibulae adductor mandibulae

￿ backwards ￿ maxillaris A *i (Ax complex: t pulls maxillary )

￿ ￿ pulls lower jaw mandibularis ) A, up A, (A2

-A 3 (A3) -A, >￿ J￿ ￿) ￿> ￿ ￿ intramandibularis adduces anterior dentary intramandibularis mentalis

Levator arcus palatini lifts hyomandibular arch levator arcus palatini lev. arc. palatini

dilator Dilatator operculi opens operculum dilatator operculi operc.

Levator lifts and closes levator lev. operculi operculum operculi operc.

Adductor add. operculi closes operculum adductor operculi operc.

Adductor arcus palatini adduces palato-quadrate adductor arcus palatini add. arc. palatini

(3 parts) bar & hyomandibular arch, ￿ palatine

dilating bucco-pharyngeal ￿ pterygoid

cavity ￿ hyomandibular

intermandibularis Intermandibularisf(anterior) draws dentaries together intermandibularisanterior

mouth Geniohyoideus (often opens (geniohyoideus) geniohyoideus

= 2 parts) protractor hyoidei inter- ￿ superior

mandibularis posterior + ￿ inferior

interhyoideus (part)

Sternohyoideus draws hyoid apparatus back- rectus cervicis sternohyoideus

and downwards

Interhyoideus (partly) constricts anterior pharynx interhyoideus (externus) hyohyoideus inferior

ventrally

Hyohyoideus constricts pharynx ventrally hyohyoideus hyohy. superior

￿ inferior ￿ inferior

￿ superior ￿ superior

Hyoideus pulls mouth and anterior

pharynx floor upwards

Levatores arcuum branchi- lift branchial arches levatores arcuum branch- lev. arc. branch, (internus

alum (externus & internus) ialum & externus)

Attractores arcuum draw branchial arches to- attractores arcuum adductor arcus

branchialum gether branchialum branchialis

￿ anterior

￿ posterior

Interarcuales dorsalis draw branchial arches to- obliqui dorsalis interarcualis dorsalis ￿ & ￿ anterior dors. complex gether(antero-posteriorly obliqui sup.

￿ inf. transversally) dorsally ￿ posterior obl. dors.

*transversi dorsalis *transversus dors,

Subarcuales recti draw branchial arches toge- subarcuales recti interarcualis ventr.

complex ther ventrally (antero-post. ￿ obl. ventralis ￿ obl. ventr. inferior

& transv.) ￿ transv. ventr. ￿ obl. ventr. superior

￿ transversa ventr.

Transversus ventralis V draws pharyngeal bones to- transversus ventr. V transv. ventr. V

g￿ther

Subarcualis(rectus) communis com- pulls pharyngeal bone subarcualis rectus pharyngo-arcualis-hyoideus

munis forwards

Coraco-branchialis coraco-branchialis pharyngo-clavicularis internu

￿ anterior (IV) dilates anterior pharynx ￿ anterior

floor

￿ posterior (V) pulls pharyngeal bones back- ￿ V (internus) ￿ posterior

& downwards

Cleithro-pharyngeus pulls pharyngeals laterally ￿ V (externus) pharyngo-clavicularis

(anterior & posterior) out- & downwards externus.

(profundus & superficialis)

Levator branchialis branchialis V arcus V pulls pharyngeal bones up- levator arcus trapezius profundus

wards

Cucullaris pulls upper pectoral girdle cucullaris trapezius superficialis

forwards & dorsad

branch, dorsalis Retractor arcus branchialis retractor arcus branch. V. retractor arc.

dorsalis

￿ ￿ dorsal of ￿ superior pulls process pha- superior sup.

ryngeal bone backwards &

twists it, draws pharyngeals

￿ inferior ￿ inf. up- back- & inwards ￿ inferior

Sphincter oesophagi constricts oesophagus sphincter oesophagi constrictorpharyngis(= ant,

(3 parts) oes. sphinct.) Downloaded from Brill.com10/05/2021 03:05:48PM via free access

* absent in Cyprinidae. ames as used by various authors (eye musculature not included).

Named used by:

Girgis Haempel (Vetter) Dietz Gregory Holstvoogd

adductor mandib. adductor mandib.

labii depressor super- -A, -A,

ioris

levator labii inferioris -A, ￿ A,

adductor mandibulae -A, ￿ A,

￿ A

lev. arc. palatini lev. arc. palatini protractor hyomand-

ibularis & lev. arc.

palat.

dilatator dilatator operc. operc.

levator operc. levator operc.

adductor operc.

add. arc. palat. add. arcus palat. adductor hyomanib-

(ant., middle & ularis

posterior parts)

intermandib. intermandib. intermandib.

geniohyoideus geniohyoideus geniohyoideus

sternohyoideus sternohyoideus sternohyoideus sternohyoideus

constrictor phar- hyohyoideus infer-

ior yngeus anterior

constrictor phar- hyohyoideus super-

yngeus posterior ior

hyoideus

levat. arc. branch,

(extern. & intern.)

adductores arcuum

branchialium

obliqui dors. inf.

transv. dors,

interarcuales

￿ obi. ventr.

transv. pharyngeus pharyngo-trans- transv. arc. V transversus ventralis

inferior versus

interarcualis pharyngo-arcuales pharyngo-(hyoideus)

arcualis

pharyngo-clavic- coraco-branchiales

ularis internus

cleithro-pharyngeus (1) coraco-branchialis retractor pharyngeus (2) pharyngo-clavi-

inferioris cularis int.

coraco-branch. depressor pharyngeus pharyngo-clavicularis pharyngo-clav. ext.

inferioris externus

levator V levator pharyngeus levator arcus branchi- levatores ossorum (ext.)

inferioris dorsalis alis externus pharyngealium

retractores ossorum levator V (int.)

pharyngealium (modified)

retractor ventro-

branch, -lateralis arcus levator pharyngeus retractor arc.

V. inferioris caudalis dors. branchialis oesoph. oesophageal-intestinal sphincter

sphincter (= post, Downloaded from Brill.com10/05/2021 03:05:48PM oes. sphinct.) via free access 8 H. MATTHES

via with The first the anterior cartilaginous caps (submaxillary cartilages) munis (partly). arises from rounded vomero-preethmoid projections. Excessive dorso-rostrad surface of the coracoid and/or clei-

movement is checked by the sigmoid ligament (at- thrum (between the inner and the outer fascia of the

forwards the tached to the rostral bone), the membraneous liga- sternohyoideus) and runs to insert on

between antero-dorsal border of the anterior ends of the 4th ceratobranchial ment the pre- (medial) maxillary and ventral border of the maxillary, and and/or 3rd-4th basibranchials; the second originates

from the antero-ventral that between the dorso-anterior processes of the max- process of the pharyngeal

is also somewhat bones to insert the anterior ends illaries. Protrusion of the upper jaw rostrally on (medial) affected by contraction of the levator arcus palatini, of the hypobranchials (hypobranchial 3) or the inner

of the which originates from the sphenotic, and runs down- posterior side of the hypohyal. Contraction

wards behind the orbit insert the external anterior and dilatation of the to on upper pharynx pharyngeal pad surface of the hyomandibular and pterygoid, lifting forces water out through the gills, and food back into

the hyomandibular arch. the posterior pharynx when this dilates after the

of the takes has been Closing mouth place through contrac- water expelled (food particles having mean- tion of the adductor mandibulae complex, the various while been sifted out through the gill-raker sieve in parts of which lie on the cheek, external to the mem- some species). This contraction is mainly effected by

bones. This the and the levato- brane muscle presents several interesting hyohyoideus transversi ventrales;

modifications in the different branchialum well the interarcuales genera, according to res arcuum as as

their mode of prehension of food. (obliqui) also contributing somewhat to this move-

maxillaris consists a muscular In most cases, the (Aj) originates from ment. The hyohyoideus of broad

and forward sheet the the the preoperculum and quadrate runs to overlying gullet (posterior to interhyoi-

the antero-external of the from the ventral of the insert on aspect maxillary, deus), arising inner edges

thus the latter backwards The bones and pulling on contraction. opercular (interopercular, subopercular)

two of the mandibularis A which lie under to insert on the parts (A2 3 ) running antero-mesially hypohyal

A from the the and/or on a medial to its fellow from the 1( originate metapterygoid (in orbit), raphe op-

and to side. The transversi ventrales from the sympletic, hyomandibular upper preopercular, posite run ventral branchial inwards run rostrad and ventrad and insert on the angular parts of the bars to meet

coronoid of their fellows but the and process. Simultaneously with closing opposite medially, transversus

the relaxation the throat ventralis IV the mouth, of longitudinal mus- inserts mesially on anterior process

cles and the adductor arcus palatini, and contraction of the pharyngeal bones.

The of the hyoideus, interhyoideus (partly) and hyohyoi- movements of the pharyngeal bones are com-

deus about of the mouth manded of muscles derived bring constriction cavity by a set specialised mainly

(and anterior pharynx), thus forcing water and food from the musculature of the 5th gill arch and working backwards. The adductor which of the arcus palatini, con- antagonistically. Enlargement posterior pharynx coraco-bran- sists of three parts, arises from the cranium (pro-otic cavity, mainly through contraction of the

and chialis and ad- & parasphenoid) runs antero-laterally somewhat posterior cleithro-pharyngeus muscles,

the dorsal surfaces of the food the teeth where be ventrally to insert on inner mits to pharyngeal area it can

palatine, pterygoid and hyomandibular bones. The masticated. The first of these muscles arises from the

hyoideus is a thin, narrow muscle lying internal to mesial antero-dorsal surface of the coracoid (being also

the arch and less with the and hyoid more or parallel to it, arising partly continuous body muscles) inserts

from the posterior basihyal region and inserting anteriorly on the ventral aspect of the rostrad ends of

dorso-posteriorly on the caudad surface of the upper the pharyngeal bones. The second originates from

The the dorsal of the ventral of the hyomandibular. interhyoideus is a narrow mus- anterior surface part cle the and dorsal the cleithrum and the lying on gullet, posterior to (external posterior to sterno-hyoi-

but ventral the and forward and the latter geniohyoideus, to sternohyoideus deus), runs medially over to

from lateral border the originates the inner surface of the posterior part insert on the inner (ventral) of pha- of the of and ceratohyal and/or epihyal, to run transversely ryngeal bone; usually, it consists an anterior

towards fellow from the which the fasciae of which each its opposite side, it posterior part, cross over

meets mesially. other.

Further back, dilatation of the pharyngeal (bran- Contraction of the posterior pharynx brings the

is the dorsal chial) cavity brought about by overall contraction pharyngeal teeth together and up against of the pharyngeal pad and by the action of the cora- plate; this is brought about by the action of the Le-

co-branchialis anterior and sub-arcualis rectus com- vator arms branchialis V and retractor arcus branchi-

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alis enable the teeth dorsalis inferior muscles, the first of which origi- as antagonistic pairs, pharyngeal to

nates in in various the sclerous the subtemporal fossa (surrounded by the work ways against upper plate

exoccipital, epiotic & pterotic) and inserts ventrally on and/or against each other, e.g.: crushing (up and the and tip and posterior edge of the ascending process of down), grinding (rotatory), lacerating (lateral)

the pharyngeals. Interior (mesially) to the origin of shearing (back- and forwards) movements. Mastica-

this muscle thin muscles which the of the actions, arise 3 or 4 small, run tion is lengthiest process feeding

observed these ventrad to insert through a tendinous cauda on the as can readily be on living fish; move-

dorso-lateral the ments be effected while part of upper pharynx wall (the 2 can respiration is going on,

anterior muscles); the posterior muscular strands run thanks to the posterior position of the pharyngeal that there interference be- along the hind edge of the ascending pharyngeal bones and teeth, so is no bone the lateral wall. mastication and process to insert on pharynx tween deglution, respiration. that Upon contraction, they draw the posterior pharyn- An important point to stress is no cyprinid has been observed mud, geal walls upwards, dilating the cavity. These mus- species to regularly pass sand,

cles derived from the levator other debris whilst the are evidently arcus or through its gills, retaining branchialis V. The second is derived from the larger organisms on which it feeds. This sorting or

sphincter oesophagi, arises from the posterior aspect sifting action is the rule in silurids and quite common of the latero-ventral of the bone in other fish but in the process pharyngeal groups, Ctjprinidae generally, and and to takes inside the mouth and runs obliquely back-, in- up-wards insert sorting-out process place

anterior material mesially on the posterior part of the pharyngeal proc- pharynx cavities, rejected being e-

also vacuated the mouth. ess (basi-occipital process). Some fibres insert on through

the dorso-lateral walls of the pharynx, and contribute This spitting movement is effected through con- branchialis dor- to its dilatation. The retractor arcus traction of the pharynx, bringing into action mainly

salis muscle the levatores superior is a small, narrow originating subarcuales, arcuum branchialum, hyo-

from the pharyngeal process (anterior to the preced- hyoideus, interhyoideus, and adductor arcus palatini

and forward mesial the ascend- with relaxation of the ing muscle) running to muscles, simultaneously coraco-

to insert a tendinous Cauda branchialis muscles, ing process, through long anterior, and sternohyoideus

onto the rostrad (inner) edge of its upper part. Con- whilst the mandible is quickly depressed (through

traction of this muscle pulls the ascending pharyn- contraction of the geniohyoideus, this also assisting in caudad and inwards, the the and the whole geal process swinging ven- raising hyoid apparatus) protru-

tral part of the pharyngeals somewhat down, the part- sile mouth apparatus thrown forwards. Thus, the

icular anterior insertion constriction of the muscle causing a tor- posterior raising the pressure and the

sion which twists the lower parts of the bones lateral- anterior protrusion (dilatation) of the mouth lowering

ly outwards; hence, the action of this muscle also con- it, a strong forwards current is set up, ejecting water tributes towards the and all loose mandibular enlargement of posterior pharyn- particles. The absence of a

valve members of this character geal cavity. in family is clearly a

in Ventrally, below the pharyngeal teeth area, the relation to this habit.

ventralis from the of Those transversus V arises inner edge species which feed mainly by a method of

the latero-ventral and mouthfuls of sediments and posterior process runs mesially picking up (bottom)

to meet its fellow from the opposite side; contraction vegetable matter, sorting out suitable food particles of this muscle draws the two pharyngeal bones to- in the bucco-pharyngeal activity, characteristically

also the teeth. Behind the have inferior well gether, approximating a strongly protrusile, mouth, as as

pharyngeals, a sphincter oesophagi surrounds the a thick pharyngeal pad and well developed gill-rakers

relaxation of this muscle whilst the form oesophagus; (pos- meshing closely to a sieve or even to completely terior) pharynx contracts, admits food to the oeso- isolate the pharynx from the gill chambers.

phagus and hence to the intestine. This muscle, Food particles, whether composed of vegetable

be divided into three animal though continuous, may parts, or matter, are retained during the spitting out

anterior constrictor of material in the namely: an pharyngis part sur- rejected following way: rounding the posterior pharyngeal chamber immedi- 1. In the bucco-pharyngeal cavity they become thor-

behind the median circular muscle mixed with and the ately teeth; a part oughly entangled in mucus around the short oesophagus and a posterior oeso- produced by the goblet cells.

its with When the mouth phageal-intestinal sphincter part, at junction 2. opens and the pharynx contracts the and the the intestine. during spitting, papillae plicae on

contractions of these muscles those the Alternating working mucous lining, especially on pharyngeal

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between Labeo pad, trap them in the anterior pharynx Cuvier, 1817.

the raised floor and dilated pharyngeal pad, the Species studied: L. lineatusBlgr., 1891 (Congo basin)

in the final of L. 1901 latter even acting as a press stages variegatus Pell., (Stanley- the constriction, squeezing out the water (through Pool, Congo)

sieve in L. annectens Blgr., 1903 (W. Africa: gill many species). Nigeria, Cameroun) There probably exists some factor-e.g. pertaining L. niloticus (Forsk., 1775) (Nile) to surface tension phenomena￿which causes the mu- (See also Girgis, 1952). adhere where- cus to closely to organic matter (food), unaffect- as will remain relatively inorganic particles General characters That this ed, and can thus be easily rejected. process Carp-like species, usually large (20-60 cm.) is far from infallible is evidenced the quite con- by be Two major groups can clearly distinguished a- siderable of etc. which are quantities sand, mud, is characterised mong the Labeo species; One by a the nevertheless regularly present in digestive tract compressed body form, relatively small head, lateral of the bottom-feeding species. rather suckerlike, transverse, eyes, small, protractile, inferior mouth with thickened fringed lips, the inner ECOLOGICAL CLASSIFICATION surface of which bears no transverse plicae (PI. I, a). The African be divided Cyprinidae can ecologically The rostrum is weakly developed and there is a per- into two major groups, i.e.: fectly formed vomero-palatine organ. forms: most of the Open-water including horie e.g.: L. lineatus, L. niloticus, L. (studied by more specialised types. Girgis, I.e.). small and Species belonging here are generally The other has a group more distinctly cylindriform carnivorous, feeding on fish, insects, Crustacea largely a wide, body, larger head, supero-lateral eyes, infe- and other invertebrates, or plankton-eating (zo~plank- bordered rior, strongly protractile mouth, by thick, ton mostly). fringed, papillose lips bearing transverse plicae, and this is characterised Morphologically, group by well limited a developed rostrum {Pi. Ill, a), poste- (streamlined) which large-mouthed, elongate species, furrow the snout. riorly by a deep transverse across also be considered as (see can ecologically "sprinters" is but is A vomero-palatine organ present, irregular The mouth Boddeke, Slijper & v. d. Stelt, 1959). in form and poorly developed. Also, the barbels, is terminal and somewhat less than usually protractile well the when present, are better developed, as as in fishes belonging to the next group. horny cutting edge along the jaws. Moreover, the of the Barili~s, Chelae- Species genera Leptocypris, don't extend far forward gill slits usually as ventrally, and thiops, Engraulicypris, Coptostomabarbus some the the gill membranes being broadly united with of the large Barbus species (the predatory ones) can isthmus, and the posterior lobe of the air bladder is be classified here. small but quite very in some species (L. variegatus)

Bottom-living forms: This group also in- normal in others (L. annectens). cludes well some highly specialised types as as most of the members of the Fishes more primitive family. Ecology of this herbivorous of first defined live group are mainly (algae, water- Members the group as above, plants), omnivorous or even detritivorous. Some mostly in large, more or less muddy streams, quiet

be small and where feed may predominantly carnivorous, feeding on backwaters lakes, they on diatoms, bottom invertebrates (insect larvae). Most however, microscopic algae (e.g. Desmids), filamentous algae, are characteristically facultative feeders. and on animal micro-organisms and higher water-

members of this of well. food obtained from the Morphologically, group consist plants as The is largely

forms with and but also from stocky well-developed sense organs (taste, (muddy) bottom banks, submerged touch), e.g. barbels, fringed, papillose lips, etc., a- vegetation, tree-trunks, rocks, etc. Though they gen- round the which neverthe- mouth, is usually inferior. Their erally live on or near the bottom, they are

also tends be less and body-form to compressed laterally. less good swimmers can easily surmount strong

These fishes be considered and may as "stayers" currents.

"crawlers", their is small as regards mode of life. In the second group, L. variegatus a spe-

The the lower following genera are represented here: most cies living in the rapids of Congo (near

Barbus Phreatich- and torrentico- species, Caecoharhus, Barbopsis, Leopoldville) has adapted to a more

Garra and Labeo. lous evidenced cylindrical thys, Varicorhinus, life, as is by its more body-

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less of the behind which lies the form, more or horizontally placed paired fins, edges jaws, enlarged

the reduction of the air bladder, etc. (see also Hora, buccal cavity (Pi. I, b & c). The premaxillaries have

their antero- 1930). It feeds mainly on the algal growth covering no ascending process (premax. pedicel),

the and the mesial ends connected the rocks, more particularly on microscopic being directly to sigmoid and the rostral bone algae and diatoms which it sucks out from between ligament hence, through lying

filaments. also able less between the anterior the algal It is a very swimmer. more or horizontally as-

the maxillaries, to the L. annectens and other members of the second cending processes of vomero-

rivers fork and left group usually live in the upper reaches of mesethmoid (Pi. Ill, b). Right premaxil-

the clearer and laries a membraneous where water is more turbulent; they are joined anteriorly by lig-

also tend be than those The lower halves to more microphytophageous ament. jaw join antero-mesially

Weber & de of the first one. through an interdentary cartilage.

studied here have mention Some species not an exceedingly Beaufort (1916, pp. 212-213, figs. 82-83) a the developed rostrum, for instance; L. cylindricus, L. large inner fold, running transversely along entire

stir in Labeo C. & V., sorex, etc., which evidently serves to up the bot- lip circumference erythropterus examined torn sediments and detritus. In the latter species the 1842 (Java). None of the African species

reduced shows this feature. When the mouth is eyes are greatly in size, indicating a prefer- however,

for habitat the draw back and outwards, ence a practically lightless (deep, muddy protruded, lips spread the river stretches). exposing the cutting jaw edges, thus enabling loose the fish to "graze" on, or scrape biological cov-

Functional morphology ering of the substrate and subsequently suck in the

External features: The rostrum consists loosened material through dilatationof the buccal cav-

hardened largely of thickened connective tissue and fat over- ity. These horny cutting edges consist of

the bones and rostral cells formed the lying upper jaw forming a flap epithelial (stratum corneum) by spe-

anteriorly, which partly overhangs the upper lip when cialised underlying epithelium (stratum germinati-

covered skin and deciduous the mouth is closed. It is by tough vum). This stratum corneum forms a hornv

The maxilla- usually bears numerous horny tubercles, particularly sheath along the jaw edges (Girgis, I.e.).

in the The rostral is bear- the and which apparent $. flap fringed, ry valve, bordering upper jaw internally

2 3 rows of small often also bears forward and ing or alternating sensory papillae tiny papillae, moves lower with the mouth along its edge. comes into contact floor, effectively

A single pair of barbels is present in L. variegatus; closing the mouth aperture, when the internal water

they are absent, or represented by a rudimentary pressure is raised during contraction of the bucco-

pair hidden in the folds at the side of the mouth, in pharyngeal cavity.

the 3 other species considered. The fleshy lips are As is the rule in Cyprinids, the mouth floor over

of small of strongly fringed by 2 or 3 rows papillae the "tongue" area bears numerous, parallel plicae,

various size. Transverse of confluent which outwards and backwards from ridges (5-8) run obliquely

papillae are present on the inner side of the lips in the median line and become deepened posteriorly.

the surface The lower some species, greatly increasing sensory epithelium between the jaw halves, in (PI. I, c). front of the "tongue", however, is entirely smooth

and Laterally ventrally, a deep post-labial groove (PI. I, c).

the lower from the isthmus separates lip or "chin";

the caudad parts of the premaxillaries and maxillaries Musculature of the mouth: (PI. Ill, b & c). also fit into this when the mouth is The short from the laterally groove geniohyoideus originates antero-

closed Pi. The maxillaries visible ventral extremities of the and the and (Pl. I, a; Ill, a). are interopercle le

laterally when the mouth is protruded. 2e branchiostegals to insert anteriorly on the caudad

buds and cells of the dentaries and Taste some mucus are present on inner edge interdentary cartilage. the lips, particularly on the papillose plicae, as well The posterior sternohyoideus, which pulls the hyoid

as on the barbels (Gibgis, I.e.). Numerous nerve apparatus down- and back-wards, dilating the buccal

also these the fossa endings are apparent in structures. cavity, inserts rostrally into urohyal and onto

the median urohyal spine (anterior part). Part of the

Buc co -pharyngeal cavity : abdominal musculature, which inserts anteriorly on

a) The prehensile apparatus: In this genus it is more the inner (caudad) surface of the urohyal also assists of a sucking and scraping apparatus formed by the in depressing the hyoid apparatus. thick, continuous lips surrounding the sharp cutting The adductor mandibulae complex, closing the

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mouth, consists of three distinct muscles, namely: Posteriorly, the thick pharyngeal pad (palatal organ)

the maxillaris which of broad the (A)), consists a mus- overhangs anterior pharynx floor, reducing the

cular sheet from the and originating preopercular pharyngeal cavity to a broad, narrow slit (Pi. I, b).

and inserts tendinous The remarkable is ovoid and quadrate anteriorly through a vomero-palatine organ

cauda on the external rostral side of the maxillary in consists of two parallel rows of broad, thick, papillose

lamellae bordered species of the first group ((L. lineatus, etc.), depresses medially, laterally by an external

the snout and back- row of thin, lamellar and pulls upper lip maxillary long, irregularly shaped projec-

wards. The mandihularis consists of two tions, in a It hes under parts (A2 & partly lying groove (PI. II, a).

under in of the first A the vomer anteriorly, the A.j) lying A]; species group, 2 parasphenoid posteriorly,

two fasciae & A" of which the the and The comprises (A' 2 2) upper palatines mesopterygoids laterally. pala-

(A' ) has two the anterior one in tal epithelium adjacent to the lamellae is 2 capita, originating finely plicat- the the the ed The number and of orbit, mainly on metapterygoid; posterior longitudinally. development

the lamellae varies from another from the hyomandibular and upper preopercular, one species to and

internal and external the levator also less in the partly partly to arcus they are developed young; usually,

Beneath the before with the number 6-10. The lateral row is variable, palatini. eye, just fusing they very

anterior and caput, it is greatly narrowed and tendinous. may even be absent altogether or reduced to a

This fascia i the inserts rostrally on the anterior inner edge ridge (L. niloticus). Though vomero-palatine or- of the mandibleand differ however dorsally sends a tendinous cauda gan may in minor details, it is quite

in to the caudad part of the maxillary in L. lineatus. constant form and size in species of the first group

but but in those the it not in the other two species studied. The lower of second group, shows a much

fascia is from the more state. (A"2 ) flat, originates preopercular, primitive

Id lower hyomandibular and the surface of A and runs L. (PI. d) two lamellar, crenul- :i variegatus I, only

to ated folds A' insert on the mandible backwards and several rostro-ventrally, joining 2, running obliquely behind serial just it. A3 originates in the orbit from the irregular, papillose projections are developed

metapterygoid and behind A' and in the oval depression of the mouth roof. hyomandibular 2, medially

runs ventrad under A to the The two lamellar folds the 2 insert on posterior inner apparently correspond to

edge of the mandible. Contraction of lifts external row of lamellar in fishes of the A 2 & A3 projections

the lower the mouth. first whereas the few median jaw, closing Furthermore, con- group, large projections

traction of A will also tend raise draft of the median lamellar 3 to the mouth floor, represent a series.

constricting the buccal cavity. In young specimens of L. annectens the oblong de-

In of the second the other of the mouth roof bordered membra- species group on hand, pression is by a

fascia and double series rounded A) possesses an upper which originates in the neous ridge a of large, orbit anterior to the head of A' and the main are a median 2 , joins papillae separated by deep groove.

muscular mass the down and anteriorly (PI. Ill, c); it probably re- Posteriorly, palate curves sharply, a presents the anterior of A' A also has semicircular, marks the caput 2. 2 two feebly papillose ridge separa-

the in the orbit tion between and fasciae, upper one (A' 2 ) originating vomero-palatine organ pharyngeal

and the lower The often call- only joining (A" 2) to insert on the man- pad. latter, or "palatal organ" as it is

dible The thin A muscle does not ed, a thick cushion-like under ventrally. :) differ is papillose pad lying

from that in members of the first the and the substantially group, parasphenoid metapterygoid anteriorly,

which to seem possess a more specialised type of basisphenoid, basioccipital and pharyngobranchials musculature. divided shallow posteriorly. It is medially by a longi-

There intramandihularis tudinal and left lobes and bears is no and no intermandi- groove into right bularis but muscle present. varishaped papillae, long anteriorly, smaller, more levator which the The arcus palatini, besides raising the hyo- numerous posteriorly, project into narrow mandibular b Pi. Thus food arch, also causes an outward swing of the pharyngeal cavity (PI. I, & II, c). be- whole Suspensorium, thus enlarging the bucco-pha- particles, entangled in mucus, will get snagged when the mouth closes and the ryngeal cavity. tween the papillae

entire pharyngeal apparatus contracts, expelling wa- the filter. b) The selective apparatus: This shows some ex- ter through gill less tremely specialised and interesting features. The roof The anterior pharynx floor is more or triangu- of the buccal behind with the backwards and a cavity curves strongly upwards lar, apex pointing plicated,

the oval from surface which becomes concave jaw region, forming an depression slightly convex poste- arches. The a the branchial which lamellar vomero-palatine organ hangs down. riorly and laterally over

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caudad of the portion pharynx floor, overlying the an- ty and the posterior mouth and anterior pharyngeal terior bone towards pharyngeal process, rises sharply cavities, while the mouth remains closed and the

the teeth the off the pharyngeal area, following upward cur- pharyngeal pad expanded, closing pharynx

vature of the This the These will pharyngeal pad. triangular portion over gill area. mouvements set up

has a directed and is also forwardly apex somewhat back and forth water currents with corresponding

thickened, forming a small ventral pharyngeal pad movements of the lamellae. Lowering and raising of

which bears small plicae running antero-laterally from the mouth floor through action of the sternohyoideus

the median line (PI. Ill, d). The curvature of the and hyoideus will also contribute considerably to the

floor is such that fits the of the pharynx it exactly onto mixing movements and even action epithelial

surface. muscularis Thus small water pharyngeal pad may not be negligible. also Histological investigation (see Girgis, I.e.) currents will pass over and between the lamellae; the

shows that the of the food the mucosa bucco-pharyngeal cavity suspended particles passing closely over epi- of stratified consists epithelium with numerous mucus thelial surface will become entangled in mucus before

cells (goblet cells) and taste buds (particularly on the being passed backwards to the pharynx. It would be

crests of the folds). These specialised cells are every- interesting to obtain experimental confirmation of this where the the present, on vomero-palatine organ, hypothesis which is mechanically feasible and further

well the valve. munch- pharyngeal pad, as as on maxillary supported by the observation of small, rapid

The goblet cells (mostly situated on the sides of the ing movements in live specimens, with mouth closed,

folds) increase in number posteriorly. The numerous alternate raising and lowering of the hyoid apparatus,

buds denote and of the taste a highly developed gustatory sense, no apparent expulsion water through gills

which again is typical for plant-eating species as well while this takes place.

for those which much a- the ceratobranchi- as engulf inorganic matter The branchial arches support on

with food The is usually als and the distal of the the long particles. epithelium part epibranchials gill less stratified and be- more or in some places even lamellae externally and the gill-rakers internally to

comified and be the The latter comes can desquamated. pharyngeal cavity. are long, slender,

The submucosa consists of areolar tissue and col- set to each closely parallel other, numerous, varying

fibres tissue in in lagen with capillaries, nerves, connective from 50 to 100 adult fish, and inserted two rows

and fat cells. few muscle strands of Though a striate laterally along each arch. Those in the outer row

in the no the first branchial than are present vomero-palatine organ, true arcn are distinctly longer

is muscularis layer developed there (PI. V, a), though those of the inner rows, more or less setiform, and

under the it is present laterally, palatal epithelium. rest against the inner opercle wall, thus completely In the muscle fibres all off the from the chamber. pharyngeal pad, striate ran in closing anterior pharynx gill

fat directions, but areolar connective tissue, cells, e- Each gill-raker is free at its distal end only in the

lastic and fibres make of inner is lamellar collagen up most its mass. rows, and joined by a membraneous,

the dorsal becomes median the Posteriorly, pharynx epithelium connection to a ridge running along more and more stratified and horny untill it abuts the length of the arch. The gill-rakers of adjoining arches

horny pad against which the pharyngeal teeth work. mesh at their distal halves only, but each bears tiny-

The regular form of the vomero-palatine organ lateral projections along the inner lamellar ridge, feed- suggests some specialised function in relation to which mesh in turn with similar projections from its

however, no muscle This whole forms a ing; voluntary being present, any neighbour (PI. II, b). apparatus

active function is excluded. Girgis (1952) studied very efficient sieve, allowing water to flow through the nerve endings by silver impregnation and found towards the gills whilst retaining all other particles

different from those the that they were no in adjacent (food, sand, mud, etc.). epithelium. Therefore, the primary function of the No distinctly formed micro-gill-rakers like those of

to be the increase in surface of the nilotica Citharinus organ seems great Tilapia (L￿ 1758) or congicus and mucous membrane brought about by its lamellar Blgr., 1897, all microphytophageous pelopha-

function be have been structure. Another passive can suggested geous species (Gosse, 1956), found in however, namely that of ensuring thorough mixing Labeo. However, numerous tiny papillae are to be

in the the of the of tiny food particles (e.g. diatoms), suspended seen, dispersed on epithelium gill arches,

before backwards and in water, with mucus they are passed may some cases (e.g. L. niloticus, L. variega-

the fitered the form a of the and water is out through gill-raker tus) regular row micro-papillae along

alternate bases of the sieve. This mixing can be brought about by gill-rakers. Even the epithelium cover-

and of the mouth the inner surface of the bear dilatation contraction anterior cavi- ing opercula may tiny

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papillae, particularly apparent in L. variegatus. at an angle of about 80 to 90￿; they are relatively show small small The gill lamellaeoften numerous trans- compared with those of other African Cyprinids

serrated and that the teeth verse ridges, giving them a appearance, as so positioned pharyngeal can prac-

well to become at their extre- work and down the dorsal as a tendency feathery tically only up against

feature which in Garra A thin from the mities, a is very prominent horny pad. long, cartilage originates

and which has to antero-dorsal of the anterior above spp. (Pi. IV, c), probably nothing part processes, the do with feeding, but serves essentially to increase their symphysis, and runs forwards to the posterior

is of ventral respiratory surface, a character which evidently tip of the basi-branchials. The posterior proc-

survival value for where downwards and but little bottom-living species oxygen esses curve sharply out-

deficiencies in the It is wards the dorsal environment are common. laterally; processes are quite straight,

observe that The three therefore surprising to this particularity curving somewhat outwards at their tips.

is most in fishes like L. varie- form border of the gills developed processes a striated bony surrounding

gatus and Garra which live in rapids, where the water the spongy part which projects medially and bears could is theoretically always well oxygenated. It be a the teeth.

feature with mechanical The teeth homodont and developed in connection pharyngeal (Pi. II, d) are

difficulties violent currents. in three the teeth formula breathing in water placed rows, being: 2-3;

+ The epithelial covering of the gill arches and gill- 3-4; 5-5; 4-3; 3-2. They have flattened, compress-

rakers and taste buds and is thin contains mucus ed crowns, some being slightly excavated and more

the tastebuds their less close and cells, gill-rakers having on inner or spoonshaped, lying together forming

and of cells + oval surface which the edge (lamellar ridge) a row goblet along a grinding projects into

each side. posterior pharyngeal cavity and works against the

upper horny plate.

Musculature of the anterior The pharynx: horny plate is a ￿ heart-shaped, hard, corni-

The narrow hyoideus muscle lies internal to the hyoid fied, deciduous, brown-coloured structure composed

connective arch and originates on the surface of the caudad por- of dense tissue and numerous collagenous

of the backwards and which attached the tion basihyal to run cranially, fibres, is dorsally to laterally

the lateral border of the broadened of the laterally (along pharyngeal masticatory process upper pharyn-

the caudad surface of the bone and covered pad) to insert on proximal geal is by a two-layered epithelium

of part the hyomandibular. It raises the posterior composed of basal columnar cells and a horny layer

mouth- and floor. The flat of enucleate cells anterior pharynx large, forming a stratum corneum (Girgis, adductor situated dorsal to This bears short arcus palatini is largely I.e.). horny layer longitudinal grooves the and lateral pharyngeal pad brings about constric- or striae anteriorly and two diverging series of tion of the the throat bucco-pharyngeal cavity. In grooves postero-laterally. The lateral wall of the pos- region, constriction of the pharynx is effected by the terior pharynx is muscular, has deep, anastomosing transverse interhyoideus and hyohyoideus muscles, longitudinal folds, which are continued into the oeso- which form a thin, broad muscular sheet lying under phagus, and numerous goblet cells to ensure efficient the branchial between the and lubrication of the The bordered arches, sternohyoideus food. teeth area is the broad and the The sub- of smooth stratified urohyal branchiostegals. anteriorly by a narrow strip epi- arcualis communis the and also, by raising pharynx floor, thelium, laterally posteriorly by a crescentic pad contributes of hardened to constrict the pharynx due to its poste- (stratified) epithelium, bearing transverse than the rior part lying higher anterior (PI. IV, b). ridges (PI. Ill, d).

Dilatationof the pharynx is effected by contraction

muscular levator of the pharyngeal pad, the arcus The masticatory musculature: (PL Ill,

levator and coraco-branchialis palatini, operculum an- c & PI. IV, a & b).

which the ventral of of the coraco-branchialis terior, inserts rostrally on aspect Contraction posterior and 4th ceratobranchial the and 3rd basibranchial and cleithro-pharyngeus muscles dilates the posterior pha- the partly on anterior cartilage of the pharyngeal rynx, admitting food to the pharyngeal teeth area. bones and the The latter muscle and of (Pi. IV, a), dilates anterior pharynx is simple consists a thin, floor. broad muscular sheet overlying the sternohyoideus

and and running obliquely caudad, ventrad laterally; The and outwards. masticatory apparatus: it pulls the pharyngeal bone down Con-

The pharyngeal bones (PI. II, d), each of which is traction of the subarcualis communis, besides raising more or less triangular in shape, meet antero-mesially the anterior pharynx floor, also acts antagonistically to

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lumen the coraco-branchialis posterior, pulling the pharyn- riorly with those of the anterior intestine; its

is and taste geal bones forwards and somewhat down, thus con- narrow, mucus cells are very numerous

tributing to dilate the posterior pharyngeal chamber buds gradually disappear; the muscularis is composed

behind the teeth. of thin of fibres and a thick a inner layer longitudinal

circular all Constriction of the posterior pharynx is effected by outer one of fibres, striate. levator branchialis The has the the action of the arcus V, retractor intestine an anterior swelling, intes-

branchialis dorsalis and tinal which followed an arcus inferior transversus bulb, serves as "stomach", by

ventralis V muscles, the first of which has two fasciae extremely long, coiled, undifferentiated intestine.

and lower fas- There is anal The mucosal folds ￿ a narrow upper one a broad, posterior, no sphincter. are

cia which originates partly in the subtemporal fossa longitudinal and few in number anteriorly (in the

ventrad intestinal anosto- and partly (the posterior portion) from the bulb), becoming more numerous, and further surface of the opisthotic and posttemporal; ventrally, mosing wavy back, finally forming zig-

the of the lines and transverse The it inserts along greater length convex cau- zag becoming posteriorly.

dad border of the bone muscularis is of smooth circular ascending pharyngeal process. mainly composed

draws the and striate and more It pharyngeals up slightly forwards, fibres, some considerably longitu-

the the The dinal fibres in the anterior bulb bringing teeth up against horny plate. being present part,

second caudad and where cells also still All that need runs obliquely dorsad, mesially, to goblet are present. be said here about the other related insert mainly on the lateral flange of the posterior organs to diges-

of the tion is that the is diffuse, scattered part pharyngeal process (upper pharyngeal pancreas being bone); this muscle retracts the pharyngeals dorsad, about in the omenta which hold the intestinal coils

inwards and caudad, bringing the teeth upwards and together, and the liver, thin, elongate and poorly

towards each other. The transversus ventralis acts developed, lying dorsally, with the relatively large,

antagonistically to the cleithro-pharyngeus, drawing elongate gall bladder medially beneath it.

the pharyngeals together. An important character of the digestive tract in

The role of the thin hranchialis relation the of the food the relative retractor arcus to nature is length

dorsalis superior (PI. Ill, c) lies mainly in pulling the of the intestine; this is expressed by the ratio intestine

backwards and inwards, this twist- The table ascending process length/standard length (body). following

downward shows the ratios found for the studied. ing movement causing a corresponding species

and outward movement of the caudad ventral pha-

teeth and consideration that relative ryngeal bone parts, separating the dilating Taking into gut length in-

the posterior pharynx chamber. When the oesopha- creases with body size (this being in relation to the condition bulk gus dilates, relaxation of this muscle, coupled with factor, a greater necessitating a pro-

contraction of the levator V, retractor inferior and the portionally much greater absorption surface) and that

pharyngeal wall muscles, will drive the finely ground the examined specimens are small-sized, L. variegatus food and hence the has than the other which into it to intestine. a longer intestine species,

be with is to expected in connection its more purely

The habit. There digestive tract microphytophageous is, however, con-

The short, muscular oesophagus has large mucosal siderable individual variation in the intestinal lengths. folds running longitudinally and continuous poste- A comparison of these ratios with those given for the

Table H

Number of specimens Size range of spec. Gut length/standard

Species examined examined length Mean ratio

(cm) (variability)

Labeo horte*,* 33 ?-58,5 14-21 ￿15,5

L. linea tus 5 9,1-31,0 12,4-19,9 16,1

L. niloticus 1 16,2 16,9 (16,9)

L. variegatus 2 8,7- 9,0 16,8-17,1 16,95

*From Girgis (I.e.)

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Carp (Al-Hussaini, 1949), i.e. 1,8-1,9, gives a good lary) are present, but small. The gill slits are restrict-

idea the Labeo. ed of great gut length in to the sides and the air bladder is small, lying far

Another interesting feature concerns the lining of forwards, the posterior lobe poorly developed. the abdominal cavity, which is strongly blackened by

cells lineatus and numerous melanophore in L. L. ni- Ecology

loticus. This black of of this lining is typical phytophageous Species genus are typical torrenticolous, bot-

fish, particularly in open-water forms, as well as of tom-living forms, as is clearly shown by their various

it is many pelagic species, and thought to be a pro- characteristic adaptations, i.e.: the body-form, hori-

ultra-violet radiation which des- zontal restricted adhesive tection against may fins, gill openings, disc,

varie- troy the digestive enzymes (Hubbs, 1941). In JL. reduced swimbladder, etc.

and L. this are the fila- gatus annectens (juveniles), blackening is They omnivorous, feeding mainly on

much less their apparent, presumably owing to more mentous algae and associated micro-organisms form-

benthic mode of life, less exposed to penetrating solar ing the biological covering of the rocks, logs, etc., of

radiation. It is also possible, however, that this pig- their habitat, as well as on the small invertebrates

is of the which find there. The food mentation merely a consequence deposition refuge is scraped off the

of metabolic waste products in the peritoneum which substrate by the sharp jaw edges and then sucked in

cannot be rid of in other dilatationsand contractions of the gotten ways (excretion). through alternating

These would be present in greater quantity in plant- bucco-pharyngeal cavity.

eating species. Functional morphology

Conclusion External features: As in Labeo, the fringed

The remarkable mechanisms in the feeding developed upper lip￿on external surface of which small

this show it to be of the also be the genus one most highly spe- papillae may present￿, papillose areas of

cialised the African the lower and the barbels have among Cyprinidae, presenting lip, a sensory (gusta-

some unique to a function. Small morphological adaptations phyto- tory) papillae are particularly ap- the lower phageous, pelophageous and/or a microphageous parent along lip fold as well as on the soft

diet. It is interesting to note that the L. variegatus margins of the suctorial disc.

group, though better adapted to a benthic mode of

life, and in a spite of more microphageous diet, shows Bucco-pharyngeal cavity :

less features The simi- specialisation in apparently important a) prehensile apparatus: This shows many

like the the larities with that of the covered vomero-palatine organ or gill-raker sieve. Labeo; jaws are with

a deciduous sheath the horny forming a cutting edge; Garra also Hamilton 1822. premaxillaries have no anterior Buchanan, ascending proc-

but the dentaries in Species studied: G. demheensis (R~pp., 1837) (Nile, ess, meet a median symphysis

and no is The East Africa, N. E. Congo) interdentary cartilage present. suspen-

sion G. congoensis Poll, 1959 (Congo: of the lower jaw is quite complex, the articular bone Stanley-Pool rapids) articulating posteriorly with the quadrate above and the (mostly) preopercular below (slightly); ven-

the articulates with General characters trally, angular a facet onto the

Small and the 1st species (7-15 cm.) with an elongate, more or interopercular branchiostegal; a ligament

less often somewhat also from the latter the between the cylindrical body, depressed, es- runs to angle

caudad of the pecially anteriorly. The paired fins are also nearly processes angular {PI. IV, d). horizontally placed. The protractile mouth is inferior, The mechanism for protrusion of the jaws is basi-

identical in the transverse, the sharp cutting edges of the jaws form- cally two genera, particularly with

slit. The less devel- the of the L.J lineatus ing a crescentic lips are more or species group.

the of the oped, continuous laterally, posterior part lower labial Musculature lip modified into a suctorial disc border- of the mouth: This shows ed several anteriorly by a labialfold. A rostral flap is absent interesting and previously undescribed fea-

but but the which tures in relation the mode life of these or poorly developed, upper lip, is to of fishes.

the and has Anterior and the quite stiff, overhangs upper jaw a crenu- to parallel to geniohyoideus￿ which lated from edge (Pi. V, b). A transverse rostral furrow, originates the rostral extremities of the 2nd often usually bearing tubercles, is present across the branchiostegal and the ceratohyal to run obliquely

One of barbels and maxil- forwards and and the border snout. or two pairs (rostral dorsad, inserts on inner

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of the behind and below the coronoid and of the a mandible, just 1935) part interhyoideus, forming pro-

which has the anterior disc adductor could process￿lies a more superficial muscle, tractor hyoidei, rep-

been named the adductor discus suctorius anterior resent its intermandibularis part and the geniohyoi-

distinct (PI. IV, d). deus its interhyoideus part. The absence of a

studied that This muscle originates from the fleshy cushion in interhyoideus in the species suggests it middle has been modified this the of the adhesive disc and runs laterally, probably entirely in manner.

dorsad and rostrad the the adductor have been de- to insert on inner dentary Similarly, posterior may muscle from the border just anterior to the insertion of the geniohyoi- rived either from superficial skin or deus. cushion rather of the On contracting, it pulls the fleshy up- geniohyoideus, or part interhyoideus.

thus when the disc further research the of these wards, creating a strong suction Only on ontogeny mus-

the also de- cles will to this is pressed against substrate; it assists in give an unambiguous answer problem.

its which insert pressing the mandible, so that the fish can open The abdominal muscle fasciae poste-

when attached the substrate. the dorsal surface of the flattened mouth even it is to Be- riorly on broad,

back the hind this muscle and ventral to the anterior part of urohyal also contribute to depress and pull

smaller disc the the hyohyoideus, another, adhesive mus- hyoid apparatus, enlarging bucco-pharyngeal ca-

cle, the adductor discus suctorius posterior, originates vity. Labeo lineatus from the anterior ventral extremities of the 2nd and The following differences from may

be with the adductor mandibu- 3rd branchiostegals and runs transversely to insert on noted in connection

the the fellow lae: postero-mesial part of disc, meeting its

from the opposite side medially. On contraction, it

the cushion and outwards. 1. The maxillaris has two fasciae, an pulls fleshy up laterally (A( ) upper

describes median tendon internal to lower and Hora (1922) a running (Aj￿) lying a one (Ata) origi-

from the centre of the disc (callous portion) towards nating on the quadrate and lower preopercular to run

anterior in dorsad and rostrad, the of the the urohyal Asiatic Garra species; lifting inserting on upper part

anterior above the tendinous of the urohyal would then exert the necessary suction maxillary immediately

insertion for attachment. No trace of this was found, however, of A^.

in in lamta the spp. studied, not even G Ham. Buch.,

an which was also examined, 2. The mandibularis much resembles the con- 1822, Asian species (A2)

there attachments dition Labeo niloticus and L. but the median though are connective tissue ante- in horie,

the rounded Hora also of the fascia (A' be- riorly, to short, glossohyal. (tendinous) narrowing upper 2 )

missed muscular neath the orbit marked. the seems to have the particular arran- is not as Besides, ante-

he describes and rior in the lower orbit is gement, though figures (p. 47) a caput originating hardly ap-

the "muscle the sides of The lower fascia is also double-lobed, single muscle, joining two parent. (A" 2)

the anterior which both but with the lower and broader. jaw", appears to represent one more developed

the and the adductor. More- A is also more than in Labeo. geniohyoideus posterior 3 fan-shaped would All other muscles show differences over, the arrangement as described by him no significant

have definite that while from the state of affairs described for Labeo. a drawback, namely, re- as

maining attached, the fish must keep the urohyal

selective (and hyoid apparatus) lifted￿through contraction of b) The apparatus: In a median oblong de-

the geniohyoideus, hyoideus and hyohyoideus mainly pression of the mouth roof, just behind the maxillary

￿which will also keep the bucco-pharyngeal cavity valve, lies a rudimentary vomero-palatine organ (PI. constricted and interfere of central elevation from which probably seriously with re- V, b) consisting a

radiate several which spiration. epithelial ridges, are longest

The anterior suctorial disc adductor appears at first parallel to the longitudinal axis of the fish. Anterior

sight to be a modificationof the geniohyoideus, but it to this and partly hidden under the maxillary valve,

could well modified intermandibularis. median of 6-7 The de- as represent a is a series papillae. oblong

However, the fact that it is paired and that a thin pression is bordered laterally by two strong ridges, muscular strand, the caudad which several lying transversely along parallel to run large plicae exteriorly.

found dissected G. this still less de- dentary margin was in a carefully In congoensis however, organ is

of Garra and the all specimen dembeensis, probably representing veloped plicae are shallower, running less a degenerate intermandibularis, weigh against it. If, more or parallel longitudinally.

the of the as in Barbus, geniohyoideus is composed an Posteriorly, plicae diverge, branching out into shallower intermandibularis posterior part (sensu, Edgeworth, smaller and ones, which bend laterally out-

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wards and into well veolar cavities. The anterior at their gradually pass over a developed processes join from that of Labeo ends median and phaiyngeal pad. This differs in in a ligamentous symphysis are

and smaller slender The that it bears much less papillose projec- prolonged rostrally by a long cartilage.

small which tions and has numerous anastomosing plicae in angle at they neet is about 100 to 110￿. The

an back- curve bend its surface, running generally in obliquely ascending processes forwards and sharply

The semicircular inwards at their thus to lie almost wards direction. ridge separating upper part, coming the buccal palate from the pharyngeal pad is also horizontally in the subtemporal fossa. This, especial-

and the latter the absent here. The mouth anterior pharynx floor, ly feature, is not case in G. congoensis,

lateral walls of the buccal where The as well as the cavity, are they point quite straight up. pharyngeal

less as Labeo. teeth V. from the internal side of plicated longitudinally, more or in Tiny (Pi. c) arise (mesial)

broadened papillae are everywhere present, but not in great the lateral face and point transversally in- number. is evident from these characters that the wards well and backwards. It as as slightly up- They

of Garra called fulfill three the formula: palate spp. is not upon to a are arranged in rows, according to

￿ Their less selective function anywhere as finely specialised as in 2;3-4;5 5;4-3;2. crown is more or

the with preceding genus. spoonshaped or uncinate, a sharp backwardly number 10 20 and directed and work The gill-rakers (Pi. IV, c) to point they can transversely against

stubbier and more the sides each other well as the The are widely spaced along as up against horny plate. of the branchial arches thanin Labeo. They alternate latter (Pi. V, b) hardly differs in form and structure

the arch that mesh from that of softer and less dis- with those on next so they can Labeo, though it is closely, effectively closing off the anterior pharynx, tinctly grooved, probably owing to the fact that the

the teeth work each other than it. e.g. during spitting movements. Nevertheless, more against against

a branchial species of this genus possess only rough

filter fit for retaining larger particles. Tiny papillae The masticatory musculature: This dif-

the branchial fer from that of LabeoJ the are present on arches, particularly at in following points: the small the base of the gill lamellae and on inner 1. The coraco-branchialis posterior is more develop- of the epithelial lamellae joining the proximal part ed (thicker). gill-rakers to the middle of the arch, thus giving them

serrated a finely appearance. 2. The cleithw-pharyngeus has two fasciae crossing A curious feature is the of the all other African feathery aspect gills over each other, as in Barbus, and

the small, transverse studied. the (Pi. IV, c), parallel ridges along genera An anterior one originating on the lamellae in Labeo cranial surface of the ventral of the already apparent some species part cleithrum, being much deeper here and also becoming larger behind and mesially to the origin of the posterior lamellae distally, giving the gill a feathery or club- fascia, which lies just behind and external to that of like the It and for- appearance. sternohyoideus. passes cranially up

wards under the posterior part, to insert on the ante-

Musculature of the anterior pharynx: rior ventral edge of the pharyngeal bone, external to the This is practically identical to that of Labeo, but the origin of the coraco-branchialis. On contracting,

lies over the broad, flattened, it the of the bone hyohyoideus ventrally pulls anterior part pharyngeal the ￿ triangular urohyal; an interhyoideus is absent; down,- back- and laterally outwards, enlarging the subarcualis communis, due to its horizontal position, posterior pharynx cavity. The posterior, superficial

contributes dilate the its which than hardly to pharynx, major fascia, originates more anteriorly in La- task the forward traction of the and somewhat dorsad and being pharyngeal beo, runs mesially caudad, bones. The coraco-branchialis anterior also inserts far behind the the lateral to insert just anterior one on the the the forwards, near tip of cartilage prolonging ventral edge of the pharyngeal bone. Its action pulls and pharyngeals anteriorly, partly onto it. the lower pharyngeals outwards, separating the teeth, and slightly downwards.

T he masticatory apparatus : The levator branchialis 3. arcus V, inserts higher up lower bones The pharyngeal (Pi. V, c) are of a dis- the as in Barbus. on ascending pharyngeal process, tinctly different type than those of Labeo; each is

or less falciform in with 4. The branchialis dorsalis more shape, a latero-posterior retractor arcus inferior

which has a rounded The inwards, and but broadening, posterior edge. runs nearly transversally slightly central of the external area surface of the pharyngeals back- and upwards; therefore, its main action con- is with small al- sists in the strongly hollowed, only a few very pulling pharyngeals together, bringing

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1913 the teeth against each other. The dilacerating action B. sqxuimosissimus Stdr., (Cen- tral of the pharyngeal teeth when they work against each Congo) other takes the B. holotaenia 1904 place as follows: after posterior pha- Blgr., (Equato-

has dilated, food invertebrates, rial West Africa) rynx admitting (small

to of kersteni Peters, 1868 (East Afri- filamentous algae) the teeth area, contraction B.

the levator V, retractor inferior and transversus ven- ca & Congo)

tralis muscles the teeth well B. lineomaculatus 1903 (East bring together, as as up Blgr.,

South E. against the horny plate, crushing the food particles. & Africa, Congo)

Subsequent relaxation of these muscles and contrac- B. pleuropholis Blgr., 1899 (Central

tion of the subarcualis communis, cleithro-pharyngeus Congo)

snout Rar- and branchialis dorsalis su- 1937 of the of posterior retractor arcus (David, ￿osteology region

" their bus 1916-). perior muscles, pulls the teeth down and apart, stappersi Blgr.,

hooked which have food crowns, pierced large par-

in ticles or become entangled algal masses, tearing General characters

these to pieces. This large, extremely variable, ill-defined genus can

well be divided taxonomically as as ecologically into The tract: several which, however, don't coincide. The digestive groups, This differs from that of Labeo in the with essentially large majority of species though, are carp-like,

of the which is much shorter in length intestine, very well-developed lips and barbels (2 pairs, generally) ratio relation to length. The mean for 3 speci- mouth which be ter- body surrounding a protractile may

examined of G. dembeensis and 1 of G. con- mens (2 minal to inferior (PL V. d). The edges of the jaws are

of 74 to 90 mm. standard is goensis) length, roughly usually rounded and covered with a + hardened, This is of direct correlation with the 4,5. course in stratified epithelium (stratum corneum). African Bar-

more omnivorous nature of the diet. The liver is bet- to bus in size from 2,5 cm. 1 metre. spp. range

ter developed in this genus and the lining of the ab-

dominal cavity is but slightly blackened. Ecology

Most Barbus species are characteristically facultative Conclusion feeders, being able to adopt almost any diet, as cir-

Garra show distinct to a torren- species specialisation cumstances require. But essentially they are omnivo-

ticolous, benthic mode of life, which itself with distinct of the expresses rous, a predominance carnivorous

well in form and the of as general development an habit. They usually prefer strongly flowing streams, adhesive as in their mechanisms, which where organ feeding they often congregate in large shoals, especial- the obtention of food from are adapted to the specifically ly during breeding season (upstream migrations). hard substrate. This of their mecha- a study feeding Some large species have become predatory and have also reveals facts nisms, some terminal with interesting concerning acquired a large, mouth, some even a

the taxonomie relationships between them and lower with genera projecting jaw. Species a tendency to- like Labeo and Barbus, to both of which it wards herbivorous appears a habit show a more inferior related in several characters. of these, in- mouth and Many acquire a horny cutting edge on the lower affini- cluding some osteological characters, point to Several of the small have become jaw. spp. plankto- ties with Labeo, though others, like those of the mas- nophageous. for indicate definite ticatory apparatus instance, a Among the species considered here, B. altianalis is with Barbus and Varicorhinus. Garra relationship large, more or less omnivorous, but mainly feeding

therefore, an intermediate in occupies position many on bottom-living invertebrates, in rivers; populations

in relation these but closest respects to genera, seems living in mountain streams where the bottom consists

to Varicorhinus. largely of pebbles and rock fragments, often develop

oversize, lobed lips ("rubberlip") (Pi. IX, a) which

Barbus Cuvier & Cloquet, 1816. facilitate the of between the greatly grasping prey

Species studied: B. altianalis Blgk., 1900 (East Africa bottom rubble. B. urundensis is another large omni-

& E. which feeds Congo) vorous species mostly on filamentous B. tropidolepis Blcr., 1900 (lake algae and water plants however, and consequently

a the lower the Tanganyika) possesses horny cutting edge on jaw, B. urundensis 1937 lower often David, (Ruanda- lip being poorly developed as well. B.

- - - _ ' Urundi) tropidolepis, a large, endemic species of lake Tangan-

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molluscs and the barbels yika, feeds mainly on crabs; vomero-mesethmoid fork. The lower jaw edge is

absent are poorly developed (1 pair) or altogether, sometimes horny and sharp, but usually the stratified

which be of life in clear waters the is less smooth may a consequence epithelium covering jaws more or

Also, or and hunting its relatively large prey by sight. finely plicated transversely to the jaw axis, these

the pharyngeal bones bear large, molariform crush- ridges usually continuous with the buccal cavity pli-

teeth VIII, cae and the a ribbed ing (Pi. a). giving jaws appearance (e.g. kerst and but B. squamosissimus, B. holotaenia, B. eni B. squamosissimus). There is no tongue, the

lineomaculatus feed- B. are small species, principally mouth floor overlying the glossohyal region is thick-

small invertebrates but raised and bears less ing on benthic (insect larvae), ened, slightly numerous more or

often on well. live in small outwards from the me- vegetable matter as They longitudinal plicae radiating

the first- dian line. The has of streams and possess well-developed barbels; maxillary valve often a row tiny

named and has base and these also be found species is predominantly carnivorous papillae along its can

rather mouth. the of the lower front of the a terminal, large along inner edge jaw, in

B. pleuropholis is a tiny (3-4 cm.), semi-pelagic "tongue" area (e.g. 2 rows in B. squamosissimus);

lakes and where feeds buds these species living in large rivers, it numerous taste are present on papillae

and benthic mainly on zooplankton Entomostraca. (PI. VIII, b).

Musculature mouth: Functional morphology of the (PI. VI, a;

External features: Except in B. tropidolepis Pi. IX, b).

and B. the barbels well de- The which the pleuropholis, sensory are geniohyoideus, originates on cerato- veloped and point forwards and downwards during hyal (and epihyal), 1st & 2nd branchiostegals, and

the search for well when the mouth the external the food, as as is sometimes interopercular (the part of

The fascia of protruded. lips are variably developed, even in B. altianalis), consists two parts: a genio-

within the same species, but lip size seems to be hyoideus superior, above and behind a geniohyoideus

quite constant in the small species and in B. tropido- inferior, lying ventral and anterior to the former and

urundensis and connected lepis. B. B. squamosissimus often to it posteriorly through an aponeurotic have reduced lips, the lower being restricted to the striation. The geniohyoideus superior is derived from sides of the jaw. In others (e.g. B. altianalis) "rubber- part of the interhyoideus, and the whole forms a

is lips" frequently occur. A post-labial groove more protractor hyoidei (sensu Edgeworth, 1935).

or less in the into An intermandibularis lies between the apparent, especially large spp., [anterior)

which fit the posterior parts of the maxillary and dorsal (ghy. sup.) and ventral (ghy. inf.) fibres of the and the premaxillary, lip corners. geniohyoideus, joining the anterior dentary branches. feature A curious in B. pleuropholis are the numer- Just behind the aponeurotic striation, a pair of small,

canals the which thin muscles from the ous sensory pore on head, are in arises tough connective tissue relation to the lateral line system, but the function of septum separating the left and right geniohyoidei, which is not yet clearly understood. Papillae are and run transversely outwards to insert on the skin rarely present externally, on lips, etc.; horny tuber- laterally, against the posterior mandible edges. A

cles on the snout also modification of these muscles have rise to are unusual, though they are a may given feature prominent of B. pleuropholis S6. There is the posterior adhesive disc adductor in Garra. no distinct rostral adductor flap and no transverse groove on The mandibulae complex differs from that

the of the snout. Carp (van Dobben, 1935) in one important

i.e.: shows distinct and lower respect, A] no upper

fascia and there muscle fibre from Buceo-pharyngeal cavity : is no originating The The mandible. the a. prehensile apparatus: general picture of the posterior branch of the Moreover,

the mouth and in is anterior tendinous cauda inserts far pharynx Barbust nearly identical upper part of the

with that of the which has forwards the The A has carp (Cyprinus carpio) on maxillary. fan-shaped 3 been studied other by authors 1925; van two one external the (A" internal many (Takahasi, capita, (A' 3), 3)

Dobben, 1935; Fiebiger, 1931; Haempel, 1909; to the levator arcus palatini. Antero-ventrally, it in-

Dorier tendinous cauda the inner surface Curry, 1939; & Bellon, 1952; Maltzan, serts through a onto

1935; coronoid A Zander, 1903; etc.). of the mandible, below the process. poor-

The premaxillary pedicels are well-developed, ly developed intramandibularis originates from the being joined through the sigmoid ligament, bearing inner anterior surface of the mandible (above Meckel's the small rounded rostral bone the tendinous in its middle, to the cartilage), inserting posteriorly on por-

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tion of A;j. In small Barhus species and young speci- Those in the outer row of the 1st gill arch are usually intramandibularis stubbier. The mens (smaller than 5 cm.) no is less numerous, more widely spaced and

free ends of the mesh with those from the present, though in some (e.g. B. pleuropholis) it is gill-rakers

A in well as an offshoot of . Moreover, arch, thus a but efficient developed, 2 adjacent forming rough

small Barbus,J Ao and are fused, A filter (PI. c). , A3 3 being represent- VI,

internal the levator When the arches ed by an anterior fascia, to arcus gill are pulled together (adduced)

A is also constricted in its fascia and the covers closed, the rakers can mesh com- palatini; 2 upper gill

(A'g). This situation is similar to that in Varicorhinus, pletely, fitting tightly against each other (Zander,

for the fusion of and A Protrusion of the those of the outer row bend forwards A . except 2 3 1903); against

mouth is effected in much the same way as in the the operculum, also touching each other. Thus, the

the anterior off that Carp, the mouth remaining half open during pharynx can be entirely closed so

search for food and when be quickly protruded fully even tiny particles can spat out or trapped￿the

food median the arches also is grabbed. groove on gill serving as a

collector for food and mucus￿and forced back into

h. The selective apparatus: Anteriorly, the palate the posterior pharynx when this dilates. Many Bar-

has striate due to the bus thus have or less bran- a appearance numerous longitu- species a more adjustable chial filter. be better devel- dinal plicae, often bearing small papillae, especially This seems to generally

These form the whereas the small posteriorly. plicae usually an anostomos- oped in large species, in ones

ing network at the anterior extremity of the palate; the gill-rakers are reduced and irregularly disposed.

in also, the lateral ones diverge posteriorly and the large B. pleuropholis, however, they are large, very

median plicae converge somewhat, before diverging stout, conical and papillose, numbering 10 (external

again just in front of the pharyngeal pad (Pi. VI, b). row) to 20, meshing closely; this is not surprising for

This pattern seems to be quite common in Cyprinids, a plankton-eating species. for Al-Hussaini (1949) also describes and figures it for The anterior pharynx floor between the gill arches

Butilus. these and bears In B. pleuropholis (PI. VII, d), muco- is narrow longitudinal, sinuose, papillose

in sal folds are few number, but large and very deep, plicae. Tiny papillae may be present also on the gill

arches and have fine bearing numerous tiny papillae in longitudinal series some species (B. holotaenia) pli-

as well as mucus cells and taste buds (Pi. VIII, a). In cae on the inside of their gill covers.

this folds down from the case, the hanging palate

evidently greatly increase the gustatory surface. Musculature of the anterior pharynx:

The thick of The thin an offshoot of pharyngeal pad mainly consists loosely broad, hyoideus appears as

and elastic fibres, the of the adductor and bound connective tissue, collagen posterior part arcus palatini

and muscle fibres all di- runs down from the caudad of the numerous striate running in aspect hyomandi-

rections, though mostly transversely and longitudinal- bular to insert on the lateral wall of the bucco-pha-

The stratified the The ly (PI. VIII, c & X, a). thick, epithe- ryngeal cavity, overlying metapterygoid.

lium bears vari-sized of the is but numerous, papillose projections posterior part interhyoideus distinct, nar- and Both this muscle and the broad which hang down into the pharynx are particu- row. hyohyoideus lie

well in the These ventral to the which is keeled. The larly developed large species. pa- urohyal, strongly

with those the branchial form subarcualis lies less pillae, on arches, a communis more or horizontally in

of intricate maze in which food become this and in related and the lower sort particles genus genera, pulls

trapped when the expanded pharyngeal pad presses pharyngeal bones forwards, but does not contribute

out water (through the gills), prior to passing the appreciably to raise the pharynx floor. It inserts the vertical 3rd food backwards to the masticatory apparatus. Taste anteriorly on thin, small, nearly hypo- buds cells also the which below the 3rd and goblet are quite numerous on branchials, join mesially basi-

which better branchial to form bone. The thin pharyngeal pad, is developed (more mus- a stirrup-like cora-

cular) than in Labeo.J co-branchialis anterior lies relatively further back

The the dif- than Labeo and gill-rakers are variously developed in in inserts antero-mesially largely onto ferent species, ranging in number from ￿ 5 (in small, the strong, thick anterior cartilage, just in front of

25 the anterior bone carnivorous spp.) to ￿ (B. urundensis). They are pharyngeal processes (PI. IX,c).

the sides of the branchial placed in two rows on ar-

The ches and connected transversely through a thick, masticatory apparatus: shallow The bones papillose (serrated) epithelial ridge to a me- pharyngeal (Pi. VII, a & b) are more or dian groove running the length of the arch (Pi. VI, d). less falciform with a long, downward curved anterior

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which meets the in the consists of two distinct process opposite one mesially a cleithro-pharyngeus parts,

broad of 70￿. From the anterior symphysis at an angle ￿ namely: an cleithro-pharyngeus profundus

median and posterior part of this symphysis, a cartilagi- a posterior cleithro-pharyngeus superficialis cross-

which the modified basibran- each Garra. The levator arcus nous rod, represents ing over other, as in

chials IV and V, extends horizontally forwards, over- branchialis V consists of 3 fasciae; a superior, a pos-

2nd basibran- and antero-internal which behind lying the basibranchials, to the (1st) terior an passes

chial. Laterally and posteriorly, the bones widen out the other two and inserts anteriorly, through a ten-

less lateral which dinous the external of the into a more or developed flange, cauda, on aspect ascending the bears large and small alveolar depressions running pharyngeal bone process; this muscle fascia pulls

the the teeth the inner side. inwards and somewhat fore- through to bases of on ascending process up-,

The forwards and wards, also a torsion to the ascending processes curve dorsally imparting pharyngeal other fasciae the more or less strongly inwards. bone. The insertion of the along

the small the consider- In species the pharyngeals are quite con- posterior (inner) edge of pharyngeals is

but the their detailed smaller and lies than stant in form, in large ones, ably higher in Laheo, probably

structure and the relative development of the various as a consequence of the more vertical (standing)

be ob- in situ and the parts can vary considerably, as may readily position of the pharyngeals stronger

served the of altianalis forward of the The on comparing pharyngeals B. curvature ascending processes.

and & of and inferior branchialium B. tropidolepis (Pi. VII, a b) specimens superior retractores arcuum vertical keel of the more or less the same size. dorsalis originate from the strong

The teeth are heterodont, of the and not the pharyngeal usually plac- pharyngeal process basioccipital on

ed the teeth formula ￿ lateral of this bone. The first muscle in 3 rows, being: 2(3);3;5 narrow flanges

B. the anterior tendon the rostral of the 5;3;(3)2. However, in tropidolepis inserts through a on aspect

inner is absent in adult the of its forwards tooth of the row specimens; ascending process (in angle cur-

but small in the Tooth size and and also has small ventral fascia present, very young. vature) a arising

form varies greatly in correlation with the ecological from the dorso-lateral posterior pharynx wall, con-

it. in- (trophic) diversity of the members of this genus. Gen- tributing to dilate A small upper fascia of the

the 2nd and 3rd teeth of the muscle affixed the lateral wall of erally, inner row are ferior retractor is to

much least the Their the larger, at in big species. crowns posterior pharyngeal chamber, dilating it; an-

are placed quite close together in each dental area, other originates from the pharyngeal process (basioc- but mesial the two areas are separated mesially by a con- cipital) and runs to the lateral pharynx wall,

siderable Their form is thin, tendinous space, especially posteriorly. to the ascending process; 3 or 4 mus-

with directed hook cle strands from the fossa mostly spoon-shaped a backwardly run subtemporal to insert

their but mamilliform also the dorso-lateral wall. at extremity (B. altianalis), (es- on pharynx

pecially the enlarged median teeth) (B. urundensis), The transversus ventralis V is also larger and

molariform conical which be (B. tropidolepis), (caniniform) or stronger than in Labeo, is to expected since

more or less with flat and the teeth here work well each other as incisor-like, crowns sharp as against up

edges (shearing teeth) like the posterior teeth of B. against the horny plate. There is no appreciable also found. difference muscular between the Bar- aquamosissimus, are frequently in arrangement

The is with bus studied. horny plate (PL VII, c) saddle-shaped, a spp.

directed and undulated masticato- posteriorly apex an ry surface which fits quite precisely against the teeth; The digestive tract:

posteriorly, it ends in a hard, rounded, knob-like out- When the food has been fully chewed, a wave ol

into the above contraction backwards from the growth, projecting pharynx medially passes posterior pha-

the hindermost of the teeth It is it the muscular portion area. a very rynx, forcing through oesophagus calcified differs that of hard, stratified structure, partly in the large down into the gut. The intestine from

whereas the small Labeo and the species, in ones it is more purely essentially in length (much shorter) in

covered with deciduous somewhat intestinal sclerous, being a brown, larger bulb, which￿especially in

horny sheath. carnivorous species￿is relatively better developed.

The ratio of intestine length to standard length

The masticatory musculature: (PL IX, c). varies from 1,0 (in carnivorous spp.) to 3,5 (in the

This differs from that of Labeo in several the omnivorous like B. it i respects: spp., altianalis), though may coraco-branchialis posterior is much stronger, also orig- even be still longer in predominantly herbivorous

exterior B. ratios inating partly on the flange of the cleithrum; spp., like urundensis. These are comparable

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with those found for the and take in order to in cold, clear european Carp (1,8-1,9) grations place spawn Rutilus in (0,9-1,9) by Al-Hussaini (1949). mountain streams. Feeding is done by scraping algae, The often blackened off and well peritoneum is quite strongly etc., the bottom, these, as as (epiphytic)

in omnivores and herbivores, but hardly so in carni- diatoms, constitute the main part of its diet. Higher

vores. plants, insect larvae, etc., are also eaten occasionally.

The liver better than is developed in Laheo, con-

of 3 short lateral and sisting lobes, two ones a great- Functional morphology ly elongate, rather diffuse, median lobe to extending External features: The mouth is large, trans- the end of the abdominal where it posterior cavity, thin rostral verse, inferior, moderately protractile; a

becomes reduced to a connection stringy bending lower is flap partly overhangs the upper jaw; the lip and out the in- ventrally widening again, overlying the lower absent, giving a shovel-like appearance to testine. The barbels reduced well jaw. are generally in size as

as in number. Characteristically, horny tubercles are Conclusion present on snout and rostrum, especially in $ ￿. The members of this show a of variation genus range V.1 the barbels much reduced In tanganicae, are in in feeding habits which out of proportion to appears size; the lower lip is represented by two small folds the relatively minor differences in morphological fea- at the mouth corners and the horny cutting edge is tures related to It must be in mind feeding. kept the lower The strongly developed on jaw only. upper

however, that Barbus is one of the more primitive the lack lip is thin; premaxillaries, as in Labeo, a fact living cyprinid genera (a generalised form), a the pedicel or ascending process antero-mesially; co- which is further confirmed its by many generalised ronoid the mandible is Barbus. process of large, as in anatomical characters. One corollary of this is that and there is no interdentary cartilage. its members are characteristically "facultative feed-

i.e.: the have distinct ers", species may a very prefer- Bucco-pharyngeal cavity: ential diet under normal circumstances, but should The The mouth floor and a. prehensile apparatus: these change, readily adapt to another, which may

lateral walls show no features, the be different. particular epithe- very

lium in much the same in Barbus being plicated pattern as Therefore, species are extremely adaptable Barbus, but much less distinctly. The palate, how- and this genus has speciated explosively whenever X, is divided into lateral the ever, (PL b), two depressions environment was suitable. The numerous species

a broad median of referred it be sub- separated by ridge finely papillose actually to can, however, split epithelial and connective tissue. The lateral plicae generically into several distinct groups, but further and here also but papillae are weakly developed, investigation of their morphology in connection with tend to become In in order to check whether deeper posteriorly. young speci- feeding is necessary, some the mens, palatal plicae are and the differences observed in the species studied are con- relatively deeper median is that it whether ridge only apparent anteriorly, so stant or not and they would lend support to evidently backwards with further taxonomie splitting. grows age.

Varicorhinus R￿PPEL, 1837. Musculature of the mouth: This differs

Species studied: V. tanganicae Blcb., 1900 (lake little from that of Barbus, but the intermandibularis

Tanganyika). lies under the strongly developed genioht/oideus; the

mandibulare inserts more on the man- (A L>) anteriorly

General characters i.e. the border of the coronoid dible, only on posterior

This includes and two fasciae: an one genus large species (25-50 cm.) very process, presents upper (A' 2 )

Barbus in in which is constricted in its middle much like large spp. most characters and part, somewhat as form, the feature the in Labeo, whereas the lower broad and flat, principal distinguishing being (A"2 ) is sharp, horny cutting edges on the jaws, especially the extending back and more or less downwards to its lower. the and origin on quadrate, preopercular symplectic.

A is distinct from and has small inner fascia 3 A2 a

which Ecology does not extend so far back into the orbit (be-

Varicorhinus lives in with hind the levator intra- tanganicae mainly biotopes areas palatini). A very small

lake shores and in mandibularis The a rocky bottom, e.g. along rocky is present. paired superficial mus-

rivers. seasonal mi- small, strongly flowing Massive cles overlying the geniohyoideus behind the aponeu-

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broader than in Barbus and in close, till the fish tilts rotic striation are met staying half-open up again,

a median raphe. completely closing it. Meanwhile, the bucco-pharyn-

geal cavity has expanded, sucking in water and loos-

b. The selective apparatus: The pharyngeal pad is ened material. As soon as the mouth has closed, a

The of contraction backwards from the buc- strongly papillose, but rather poorly developed. wave passes

17 the cal towards the the gill-rakers are short, but numerous: (in exterior cavity anterior pharynx; water is

and strained the the row) to 35; they are compressed (lamellar) placed out through gill-raker sieve, expand-

ed and food along the lateral edges of the gill arch, leaving a pharyngeal pad acting as a press, par-

ticles￿which well mixed with shallow, longitudinal groove medially. Tiny papillae are by now becoming

the of the branchial arches sucked the which are present on epithelium mucus￿are into posterior pharynx

action and as well as on the inner side of the gill-rakers. The dilates through the of the masticatory

mesh wall musculature. Admission of food latter can very closely, forming an adjustable, pharyngeal

fine branchial filter, which is intermediate in struc- (plus mucus) is probably also facilitated by the pres-

drawn ture to the rough filter of Barbus and the extremely sure of the water which has been subsequently

Labeo. fine one of into the bucco-pharyngeal cavity during respiratory

In spite of the thin pharyngeal pad, the pharynx is movements; when the anterior pharynx constricts to

and be closed the the very narrow dorso-ventrally can easily expell water through gills, posterior pharynx allow food be completely through contraction of the anterior pha- may briefly dilate somewhat and so to

in. masticated￿move- rynx muscles, whose arrangement does not differ washed After being thoroughly

from that Barbus. which be observed in ments can clearly in living speci-

mens￿the oesophagus dilates while the posterior

The masticatory apparatus: pharynx constricts, admitting food to the gut. The Barbus pharyngeal bones (PL X, c) are of the

their do not bend The tract: type, though ascending processes digestive

inwards. meet This shows difference from that of but the so sharply They in a long anterior no Barbus,

of symphysis, at an angle about 60￿. The pharyngeal intestine is distinctly longer, being comparable in re-

teeth in three the formula lative that of which has are placed rows, being: length to Garra, a very simi-

￿ Those of the lar diet. The 2;3;4-5 5-4;3;2. innermost row are ratio intestine length/standard length

with but excavated the other ￿ determined 5 larger, slightly crowns, is 3,2 (young) 5,0, as on specimens. teeth less than having more or spoon-shaped crowns which The gut also shows more circonvolutions in

lie close Barbus is blackened. together, forming a grinding surface compar- and the peritoneum strongly able to that of Labeo. The teeth also come into con-

tact medially and work mostly up against the horny Conclusion The surface akin of plate. masticatory formed by them lies Though V.tanganicae has a diet very to that

free from the interstitial and a life, quite adjacent plicated Garra spp., it leads much more free-swimming

epithelium, and not, as generally in Barbus, more or to which it shows definite adaptations. Morphologi-

less in it. embedded cally, Varicorhinus appears most closely related to

The identical of features horny plate (Pi. X, b) is to that Barbus, Ithough it also shares some with La-

the Barbus and also shows de- beo and with further large species a strong particularly Garra. Only re-

of calcification. search determine whether characters for gree can like, in-

The musculature of the pharyngeal bones hardly stance, the absence of premaxillary pedicels, are in-

differs in from any respect that of Barbus, the only dicative of any direct relationship with the latter two

difference the lesser and noteworthy lying in development genera, or only secondarily independently ac- of the which thinner. the cleithro-pharyngeus, is relatively quired, as is probably case.

Prehension, de glut ion and mastica- Barbobsis Di Caporiacco, 1926.

tion: Species studied: B. devechii Di Cap., 1926. (Somali- V. has been tanganicae observed (in aquarium) to land) swim obliquely and rapidly towards the bottom with

mouth the lower the General open, jaw scraping along sur- characters face the fish of stones as reaches them, often Small much like but leaving species (6-10 cm.) very Barhus,

a distinct track several the cm. long in algal covering. body not compressed, scales absent or reduced (small,

this the mouth to small. Colour the During scraping-off process, begins under the skin) and eye very light,

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back scarcely darker (more or less depigmented). The intestine is quite long (intestine length/stand-

ard = with wide length 4,2), a short, anterior bulb,

itself Ecology and is bent back upon and thrown into 3-4

Fishes of this known from small coils. The liver Barbus and the abdominal species are streams, is as in

springs and wells of Somaliland, where they live on lining quite strongly blackened.

the bottom, preferably in dark places, probably even Conclusion burrowing into the mud at times (during dry periods). This derived from Barbus This be deduced from their genus is a primitive can morphological aspect, clearly

its in but has acquired some characters of the reductions scalation, eye, pigmentation, etc. type, special

own in relation to its habitat and feeding. The The single specimen examined had mostly fresh, her- par-

baceous material ticular features show ad- plant in its gut (water-plants?) as concerning feeding typical

and small to a phytophageous diet (strongly plicated, well as some filamentous algae, sand grains aptations the invertebrates. papillose bucco-pharyngeal lining, increasing

surface, well taste sensory probably developed sense,

which is rather in Functional morphology longer intestine, etc.), surprising a

barbels fish with cavernicolous tendencies, a or There are two pairs of well-developed pres- polyphageous diet the rule the nostril of short tube even a in ent; anterior consists a (% detritiphageous being species

in such an environment. Another mm.); numerous parallel sensory lines (pits) are pres- living noteworthy

in small Barbus The characteristic is the nature of the mas- ent on the head, as some i f spp. unspecialised mouth is inferior, large, with normally developed lips, ticatory apparatus, especially the teeth, which are of

the lower separated from the "chin" by a post-labial a very generalised type.

is groove which deeper laterally. The ascending Coptostomaharbus David & Poll, 1937. of the is short. process premaxillary Species studied: C. wittei Dav. & Poll, 1937 (upper The musculature of the mouth and anterior pha-

does differ from of Congo). rynx not appreciably that Barbus, (see David, 1937.) that A which is not except 3, completely separated

from A , inserts further back on the mandible (as in 2 General characters Labeo). This tiny species is distinguished from Barbus￿to An intermandibular is apparently not developed. which it is related￿mainly by its supero-terminal, The adductor mandibulae muscles are overlain on the nearly vertical mouth. The osteology and dynamics tissue in cheek by fatty which lie the sensory pores, of the mouth and head region of Coptostomabarbus which well innervated the are by hyomandibular has been studied by David (I.e.) and its close relation- ramus of the nervus facialis (VII). ship to Barbus confirmed. The main osteological dif- The lining of the bucco-pharyngeal cavity is dis- ferences the mechanism concerning prehensile are: and the tinctly plicated longitudinally papillose; on

central of 5-6 and palate, a group very large long 1. The long premaxillary pedicels. projections, hanging down into the mouth cavity, 2. A longer, more slender maxillary. form of well- a sort vomero-palatine organ. Numerous The mandibular 3. only articulating with the quad- the developed papillae are present on pharyngeal pad rate.

which is similar to that of Barbus. The gill-rakers 4. A feebly developed rostrum, mainly consisting of number 8-10 in the external 13-15 and ossified row, internally; (elastic) connective tissue, a weakly

they are relatively large, well developed, strongly rostral bone.

papillose (micro-papillae), meshing closely, as in Bar- 5. The absence of the superior part (posterior to the bus altianalis. rostral bone) of the sigmoid ligament. The bones and musculature also of pharyngeal are 6. A cylindrical cavity in the anterior mesethmoid, Barhus the type, though more simplified (more primi- into which fits the rostral bone dorsally. tive?). The pharyngeal teeth resemble those of small 7. The mobile sub-maxillary cartilages. Barbus spp., with spoon-shaped, hooked crowns, 2-3

of the innermost and work These characteristics forward row enlarged, they can permit a very strong each other well of the mouth the lower against as as upwards. However, protrusion (especially jaw),

there of teeth each thus tube of Barbels ab- are only two rows on pharyngeal forming a sucking sorts. are

formula ￿ The situated close bone, the being: 2;5 5;2. horny plate sent, the lips are thin, the nostrils up

is sclerous, uncalcified, like in the small Barbus the orbit. spp. against

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less rather Ecology are more or straight, obtusely pointed,

of with sometimes hooked This fish lives in quiet, open back-waters large a slightly point anteriorly, work and feeds and all the same size. can rivers on zooplankton (mostly crustacea) roughly They against which it sucks in though its tube-like mouth. Occa- each other as well as against the horny plate.

also The musculature is similar sionally, planktonic algae are ingested. masticatory essentially

to that in Barbus, but some differences are apparent,

for does not show Functional morphology the cleithro-pharyngeus, instance,

into and The most prominent feature of the buccal cavity is, a separation deep superficial parts.

well rod-like The intestine is short and coils surprisingly, a developed, tongue (PL exceedingly only

missed back itself the ratio intestine X, d). This feature was apparently by David, upon once; length/

standard = a of a length 0,7-0,85 (3 measured). though it shows quite clearly on micrograph specimens

is blackened. transverse section of the snout region (page 15), The peritoneum distinctly where it lies in a deep fold of the mouth epithelium between the left and right geniohyoidei muscles. Conclusion

which This is in that it has This tongue is formed by the long glossohyal species especially interesting is lined with epithelium and completely free ante- developed a very specialised prehensile mechanism,

rise clu- riorly. which through convergence, has given to a Also the of Through contraction mainly of the geniohyoideus peoid type of mouth. development a feature and probably also the anterior pharyngeal muscles tongue constitutes a unique among Cijpnni-

dae. These characters have evolved in connection (hyoideus, interhyoideus) adducing the hyoid appa-

mouth floor. with mode of and its ratus, it can be lifted clear of the On its feeding, ancestors probably

resembled of the small Barbus like the anterior palate, two ventral projections of the closely some spp.

bones between which the of B. B. mocoensis Trew., 1937, etc. palatine appear, point pleuropholis, closed. The the tongue fits when the mouth is action

Hamilton of the tongue is largely passive apparently, though it Barilius Buchanan, 1822.

aid in food and then in studied: moorei 1900 Tangan- may holding particles pushing Species B. Blgr., (lake them backwards when the mouth closes. Its close yika)

Clu- resemblance to the tongue of plankton-eating B. christyi Blgb., 1920 (Congo

of peids provides an interesting example convergent basin) adaptive evolution.

The bucco-pharyngeal epithelium shows small lon- General characters

is size gitudinal plicae and a papillose pharyngeal pad Barilhis species range in from 10 to 50 cm.; present, overlying the gill arches. The gill-rakers, the body is elongate, streamlined, the mouth moder-

9 (ext. row) to 15, are lamel- terminal, often numbering quite long, ate to very large, slightly oblique, fine the lar, forming a sieve. without lips. The sub-orbitals are large, covering

The musculature of the mouth and has barbels absent nostrils close the pharynx cheek; are ,the to not been studied, this would have involved the is the extend further as com- orbit, eye large, gill-slits plete dissection of one of the few type specimens. A forwards ventrally than in Barbus; the tailfin is deep- superficial examination, however, showed the A! part ly forked, the colour silvery. of the adductor mandihulae to insert through a ten- dinous cauda the widened medial of the on portion Ecology maxillary, and the marulibularis (A to insert These fishes forms, which 2 large- are carnivorous, open-water

the border of the insect adult insects ly on posterior coronoid process. feed on free-swimming larvae and

The pharyngeal bones are very similar to those of (falling into the water), Crustacea (shrimps), fish, etc.

on much smaller the lateral like Barbus, though a scale; They are fast, strong swimmers, can jump trout, ventral much better to which show and flanges are relatively developed they a superficial resemblance,

than B. with (even more so in tropidolepis), a strong are often seen jumping after low-flying insects. They ventral extension the live in clear lakes and posteriorly; ascending processes mostly fast-flowing streams,

inwards small are quite straight, only bending slightly at usually in groups. their upper ends. The dorsal horny plate is rather

it distinct sclerous soft, though possesses a covering. Functional morphology

The teeth in 2 sometimes the External features: The are usually rows, 3, dentary symphysis formula being: 0(1);2(3);4(5) - (5)4;(3)2;(1)0. They often forms a knob (PL XI, a) which fits into a cor-

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in when the anterior ends of the 2nd branchio- responding median notch the upper jaw hyal and the 1st &

mouth this aids the and is closed; structure in retention stegals is composite, as in Barbus, forming a

striation is of large prey, also crushing it. The premaxillaries protractor hyoidei, but an aponeurotic

maxil- absent An in- are not very protrusile, both premaxillaries and barely apparent or even (B. christiji).

laries sliding under the sub-orbitals laterally, when termandibularis (anterior) is present, lying entirely

the mouth closes. The premaxillary pedicels are under the geniohyoideus, between the anterior dentary

long, passing back- and upwards under the median extremities.

ligament joining the rostrad ends of the maxillaries. The adductor mandibulae complex (Pi. XII, b & c) maxillaris The rostral bone and sigmoid ligament fit posteriorly shows some particular features, namely: the

into a median of the between (A consists of two distinct i.e.: A depression mesethmoid, t ) portions, ( a, origi-

and dorsal to the antero-lateral preethmoid projections. nating from the quadrate and preopercular, and in-

This shows similarities with that the external of the maxil- arrangement in Cap- serting on median, aspect itself divided tostomabarbus. Horny tubercles are characteristically lary through a tendinous cauda; it is

in into lower fascia. is present on the snout <5 <3 ■ an upper (A'j￿) and A\￿,

muscle the and a thin, narrow overlying maxillary

of the Bucco-pharyngeal cavity: originating on the median, widened portion

The The knob latter, dorsal to the insertion of it runs caudo- a. prehensile apparatus: symphysial just Aja;

which also shows the above is poorly developed in B. moorei, ventrally to insert on quadrate just its artic-

less extreme backwards extension of the mouth which ulation with the mandible. Contraction of this muscle

in when the mouth is the extends to behind the orbit B. christyi (PI. XI, a). already open, pulls quadrate

The long mandible articulates with the quadrate (and posterior mandible) up and the maxillary down,

and with the thus further the of the mouth. only, connects through a stout ligament widening gape

and the The mandibularis is flat, ex- preopercular interopercular. (A2 ) large, fanshaped,

far behind the orbit and Numerous small, parallel ridges (PI. XI, b) run tending upwards originating

the which covered with from the the the transversely across jaws are preopercular, hyomandibular, ex- levator more or less cornified, stratified epithelium. The ternal surface of the areas palatini (which ex-

mouth floor of the lower tends downwards below the level of the and narrow jaw is strongly con- to orbit)

which from the It the vex, bearing numerous parallel plicae run more cranium (sphenotic). inserts on poste-

less surface coronoid or transversely, gradually curving backwards rior inner of the well-developed

laterally. Rows of sharp papillae occur and also two fasciae (A' & A" ). tiny usually process comprises 2 L)

in the the is thin not distinct from everywhere bucco-pharyngeal cavity on A3 a muscle, very A>, lying

crests of the folds, even on the "lips" externally. A under its anterior portion and originating from the

of rounded in the orbit row papillae (PI. XI, b) appears laterally metapterygoid posterior (internal to the between the hind of the and the base lev. it inserts the coronoid edge upper jaw arc. palat.); on process of the well all the intramandibula- maxillary valve, as as along inner anteriorly to A->. A feebly developed border of the lower Like similar jaw. papillae in ris is present. Barbus these also some species, are probably gusta- selective tory. b. The apparatus: The palate bears longitudinal plicae, the sharp As such, this is generally poorly developed in Barilius

papillae on their crests becoming larger and more and in related genera. The thin, very poorly devel-

numerous posteriorly, where the plicae gradually di- oped pharyngeal pad, resembles that of (small) car-

before into the nivorous Barbus and bears verge passing over pharyngeal pad. species numerous, sinuose,

The 2 3 median At less with or plicae are distinctly deeper. its more or longitudinal plicae pointed papillae

extreme anterior end, partly below the maxillary which become deep, sinuose, lamellar ridges with

small valve, the palate shows a median pad which crenulated crests posteriorly. On the pharynx floor,

is often with two the between the arches is wider than in usually strongly papillose, one or space gill

large papillose (arborescent) projections (￿. moorei). Barbus and bears a few large, sinuose, longitudinal

This which also has which others added all structure, probably a predomi- plicae to are postero-laterally,

function, is in towards the teeth area in the nantly gustatory veiy poorly developed converging posterior B. christyi. pharynx.

The gill-rakers are degenerate, irregular in size and

Musculature of the mouth: (PI. XII). form (more or less conical) and reduced in number

The long geniohyoideus originates from the cerato- (6-12). They alternate in adjacent rows, but cannot

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mesh the from the the formula ￿ closely and shut off pharynx gill being: 2(3);5 5;(3)2. They are more

chamber. is in less homodont This, however, unnecessary open- or of equal size, (conical with a back- and water forms which feed on relatively large prey, wardly directed point) and they work mostly against off small each don't have to spit out or strain particles. A other (dilacerating action). The masticatory considerable number of also has form less tiny, sharp papillae are plate a more or like a camel-saddle, is

the branchial cornified and bears present on arches, particularly apparent scarcely small, sharp projections. The well the in B. moorei. small, sharp papillae, as as Both teeth and masticatory plate are largely hidden

lamellar mechanical posterior ridges, mainly serve a in the deep lamellar ridges and the papillose, crenul-

function, namely, that of retention of the prey. ated projections of the posterior pharyngeal wall.

These ridges are continuous with the large, smooth Musculature of the anterior pharynx: the longitudinal ones in oesophagus. An interhyoideus is absent; the hyohyoideus (PI. XII,

is broad muscle sheet the ventral a) a lying on gullet, The masticatory musculature: This dif- the and forwards and to urohyal, runs obliquely me- fers from that Barbus in minor of only some respects, its from on the inner surface of the the the sially origin cleithro-pharyngeus (especially posterior su- branchiostegals and ventral of the edge subopercular. perficial fascium) being relatively better developed

Its anterior fibres also insert on the mesial- hypohyal and the antero-internal fascium of the levator arcus

The flat hyoideus from the lower branchialis towards the of the ly. originates hyo- V inserting more tip

mandibular and and runs ventrad upper preopercular subarcualis corn- ascending pharyngeal process. A between the membrane bones of the cheek and the the caudad munis inserts anteriorly, as inl Barbus, on and the lateral mouth epi- cerato-hyals to insert on aspect of the vertically placed, slender, curved 3rd floor and The coraco-branchialis anterior basihyal. hypobranchial, which is relatively much stronger in runs from the cleithrum and rostrad, passing this A thin cucullaris muscle upwards genus. is present, run- laterally against the anterior extremity of the pha- ning from the cranium (pterotic) to the upper cleith- ryngeal bones, to insert mesially on a vestigial carti- rum, externally to the pharyngeal bone. The retrac-

4th in the branchialis dorsalis de- laginous hypobranchial, lying pharynx tor arcus superior is strongly floor, in front and just of dorsad to the anterior ex- somewhat the veloped, as in predominantly carni- tremity of the pharyngeals. vorous Barbus spp. (B. holotaenia), where it also ap- The short from the dor- sternohyoideus originates in pears relatively larger (thicker) contrast to most

sad surface of the antero-ventral extension of the the of the species. As already mentioned, action mas- cleithrum and the of inserts mesially on anterior half to ticatory muscles tends bring the teeth against each the keel of the which is but large, triangular urohyal, in motion other a transverse more than up towards flattened Part of the abdominal slightly laterally. the masticatory plate.

musculature inserts on the posterior half of the uro-

hyal keel and also contributes to lower the hyoid The digestive tract:

The intestine is apparatus. exceedingly short, nearly straight, the ratio intestine length/standard length being 0,6- The masticatory apparatus: 0,75 (measured on 4 specimens). This is comparable The bones falciform and pharyngeal (Pi. XI, c) are to the ratio for Gobio (0,65-0,85), a bottom-living, slender, with long anterior processes meeting at an carnivorous species (insects and other invertebrates), angle of ￿ 50￿ and rather loosely united in a short the intestinal bulb as given by Al-Hussaini (I.e.); also, ligamentous symphysis, prolonged anteriorly by a is large and well-developed. The pancreas is diffuse, less poorly developed, thin, more or ligamentous as in all Cyprinidae studied, and the liver is large, cartilage, which is even absent altogether in small consisting of two dorso-lateral, elongate lobes. The specimens. abdominal cavity is lined by silvery epithelium bear- The alveolar lateral area is much reduced; the as- ing large, scattered melanophores, giving it a spotted cending processes bend sharply inwards and slightly appearance. forwards their ends. at upper The pharyngeals are

of the found in more type european Cyprinids of the Conclusion

Leuciscus than like those of Barbus. Barilius and related form a different genus Compared genera group

Leuciscus Barilius has smaller the African to cephalus, teeth, a altogether among Cyprinids, especially

less alveolar and lacks the first outlined in developed area a postero-ven- ecologically (belonging to group as

tral process on the pharyngeal bones. the ecological classification). They show characteristic

The teeth towards mode of life with pharyngeal are arranged in two rows, specialisations a predatory

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a corresponding great simplification of the selective tory plate is not largely hidden by the surrounding mechanism as opposed to specialisation of the pre- papillose projections. hensile Their The musculature shows minor differ- apparatus. prey being generally quite only some

and in it large captured open water, does not have ences from that of the preceding genus, the mandibu-

to be from separated other material (detritus, bottom laris (AoA.j) consisting of a single muscular mass in

and selective which the division into various fasciae is indis- sediments) consequently a apparatus very

in becomes unnessary. Selection as such takes place tinct. Also, the coraco-branchialis anterior has a the mouth itself, where most taste buds are situated, somewhat more anterior insertion. rejected objects being immediately spat out (aquarium The digestive tract differs only from that of Bari- observations on B. moorei). They must be able to lius in that the abdominal lining is distinctly blacken-

catch elusive hence the coils back itself. prey, large mouth, strongly ed and the short intestine once upon

lower and mandibular The anterior intestinal bulb is the ratio protractile jaw specialised very large; articulation and musculature. This type of specialisa- intestine length/standard length is about 0,7. tion has been carried further in B. christyi than in B. moorei. Conclusion

Engraulicypris, which is apparently directly derived Engraulicypris G~nther, 1893. fact be of from Barilius, appearing in to a sort pigmy Species studied: E. minutus (Blgr., 1906) (lake Tan- form of it, nevertheless shows some distinctive char- ganyika). its acters which are also in correlation with mode of

General characters life; the well-developed gill-rakers, for instance, being

towards diet. Small fishes (5-12 cm.) mostly elongate "pelagic" an adaptation a plankton-eating

forms, closely resembling Barilius. The terminal mouth barbels 1899. is large, oblique, lipless; are absent. Chelaethiops BOULENGER,

Species studied: C. elongatus Blgr., 1899 (Congo, Ecology Nile, West Africa: Niger). Open-water forms living in lakes and large rivers where they occur in shoals, on zoo- generally feeding General characters and small the surface. plankton on insects, near They Very like the preceding genus, but with keeled scales look much like small of the very pelagic Clupeids the mid-ventral the on line, anterior to pelvic fins, is genus Engraulis, from which their generic name and gill-membranes narrowly united to the isthmus derived. The lacustrine show seasonal species no anteriorly, the gill-slits extending far forwards ven- spawing migrations up-river. trally; body strongly compressed. This small species

resembles of the Chela Functional morphology strongly some Asiatic spp.

The knob Barilius symphysial is pointed, fitting as in into a Ecology notch of the upper jaw; the premaxillaries are also forms on zoo- somewhat more protractile. The mucosa of the Open-water (in large rivers), feeding small the surface. bucco-pharyngeal cavity is finely plicated longitudi- plankton, insects, etc., near

nally, the plicae becoming deeper posteriorly. Tiny also Functional papillae are present, more numerous and larger morphology but Barilius. The In most of its features it is identical to posteriorly, not as pointed as in Engraulicypris,

but the knob is small, indistinct; the pharyngeal pad is somewhat better developed and symphysial gill-

rakers are but not quite as more strongly papillose. short, stubby, poorly

as in Barilius, and can mesh to form a The gill-rakers are well developed, numbering 12 developed

side less in (on inner of the 4th arch) to 33; they are long very rough, more or adjustable filter, as and pointed (especially in the external row), slightly Barbus.

is compressed (lamellar), smooth, and mesh closely, The bucco-pharyngeal lining plicated, with rows

fine branchial of small the crests of the forming a relatively sieve. papillae everywhere on

Barilius. There The masticatory apparatus is practically identical folds, exactly as in is, however, no the and the to that of Barilius; the slender pharyngeal bones bear small, papillose pad on anterior palate

of hooked but this to be 2-3 rows proportionally large, conical, plicae are proportionally larger, seems

- in of teeth, the formula being: 0-l;3;5 5;3;l-0. the case all small (young) specimens every spe-

teeth embedded the and therefore be considered The are in strongly plicated cies, cannot strictly as an and papillose epithelial tissues, but the soft mastica- adaptive character.

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is is identical that of as in Barbas. There no median papillose The masticatory apparatus to function,

teeth in on the anterior palate. Engraulicypris. The pharyngeal being set pad The is developed, as in Ba- 2-3 the formula: 0-l;3;5 ￿ 5;3;l-0 pad poorly rows according to pharyngeal ' rudimen- but more the are The cranial musculature shows no differences from rilius, papillose; gill-rakers

reduced to short, that of Barilius. tary, being widely spaced, finely

in number. Therefore, The short coils back the ratio stumps, 5-12 they gut once upon itself, papillose form functional sieve. is The cannot mesh closely to a intestine length/standard length ￿ 0,75. peri- is The musculature of the mouth and pharynx very toneum is only weakly blackened.

similar to that of Barilius, but the geniohyoideus

the intermandi- Conclusion shows a distinct aponeurotic striation;

insert bidaris is absent the fasciae of A a Like the is or vestigial; t preceding genus, Chehethiops probably rostrai a tendinous cauda on the more derived from Barilius and has adapted to a more or through long,

of the A and A are or but in- maxillary. 2 3 not, less pelagic mode of life, but its specific morphologi- part muscular cal less marked than in subdivided and appear as a single adaptions are Engraulicypris. distinctly is thinner and also mass. The hyohyoideus relatively

Leptocypris BOULENGER, 1900. lies ventral to the urohyal, which has the same form

Barilius and Barbtts. Species studied: L. modestus Blgr., 1900 (Central as in The does differ much Congo basin). masticatory apparatus not

from that of Barilius; the pharyngeal teeth are ar-

in the formula 3;5 ￿ 5;3; General characters ranged two rows, being:

fishes much like the bones the Small, silvery (6-12 cm.) very Bari- however, pharyngeal are stockier, an-

lius ,but with a less sub-inferior terior shorter, at of 70￿, smaller, more or processes meeting an angle ￿

mouth XI, and the anterior and bor- and the dont bend as (PI. d) posterior upper ascending processes ders the forwards. of eye covered with translucent fatty tissue, strongly

of has forming an adipose eyelid sorts. The masticatory plate a proportionally larger

than of with mamil- area in Barilius, irregular form, a

Ecology lated, finely papillose, uncornified working surface; it

These fishes in live shoals in the open-water reaches is not embedded in the surrounding papillose epithe- of large, generally muddy, rivers and feed mainly on lium.

small Crustacea insect larvae and adults The musculature shows few (Ostracods), pharyngeal only a

(caught near the surface). Vegetable matter (herba- minor differences from that of Barilius,J the suharcua-

and sand, also ceous) etc., is regularly ingested, prob- lis communis inserting via a long tendinous cauda on

to ably accidentally, when they come feed on the the basihval and the retractor arcxis hranchialis dor-

banks bottom. salis or superior being tendinous and very thin.

The digestive tract closely resembles that of Bari-i Functional morphology lius, but the intestine is somewhat longer, the ratio The dentary is no knob symphysis simple, symphysial intestine length/standard length being: 0,85-1,0 (3 the being developed; mouth is more protractile than and coiled back specimens) once upon itself. The in Barilius, the the especially upper jaw; premaxillary intestinal bulb is also less developed and the two liver pedicels are shorter; the mandibular articulation is lobes less The abdominal are elongate. lining bears

exactly as in Barilius. scattered melanophores. The epithelial lining of the jaw just inside the mouth shows transverse but the ridges, on upper jaw Conclusion it is smooth. The nearly mucosa of the have bucco-pha- Leptocypris species apparently reverted to a ryngeal few, but well devel- wider of foods and also cavity presents relatively range to feeding on the bot- oped, deep plicae and numerous rounded, large pa- tom, though remaining essentially carnivorous. This pillae are often on the evidenced the everywhere present, (especially is by more protractile mouth, the more and palate as pharyngeal pad) appearing rows of strongly papillose bucco-pharyngeal lining with its in-

more less flattened large, or or of creased surface for patches pads papil- area greater mucus production lose tissue. A row of rounded borders the papillae and better taste sense, a longer gut, etc. However, an lower and the valve also jaw internally maxillary is efficient selective apparatus has not developed and papillose, bearing 2-3 rows of small papillae along its therefore much detritus and indigestible material base. These probably serve a predominantly gustatory (vegetable matter, sand, etc.) is also found in the gut.

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reduced in number and of a more Leptocypris seems to be a more generalised genus, simple type (primi-

showing considerably less extreme specialisation than tive) in the carnivorous members of the family, espe-

Barilius but nevertheless the Barilius to a predaceous habit, prob- cially group. the smaller ones￿and ably derived from Barilius-hke ancestors and it is not Some species￿especially

form. show characters which to be of neo- necessarily a primitive genera appear

tenic nature. The reduction in number of pharyngeal

teeth, various simplifications in tooth form, bone GENERAL CONCLUSIONS AND DISCUSSION development and in the musculature provide positive Some conclusions be drawn from this interesting can evidence of this. For instance, small genera like the of study, not only concerning diversity feeding Barbopsis, Coptostomabarbus, Engraulicypris, etc.,

mechanisms and their relative in the and muscular features which also development present osteological different but also the genera, concerning systematics appear in small iBarbus and Bariliusj species, as well

of the African The question arises as to Cyprinidae. as in young specimens of the larger species. in which of feeding mechanisms are primitive The types well-developed coronoid process is an impor-

and which are element forms with Cyprinids consequently, genera primi- tant in a strong biting power

tive systematically. (higher torque about the jaw articulation) and is in be classified The African Cyprinids can broadly relation to the mode of prehension rather than to the

3 fundamental i.e.: Labeo a Barbus] into types, a type, type of food, being almost equally well developed in

type (including Barbus, Caecobarbus, Barbopsis, forms with cutting and scraping jaws (Garra, Labeo) Varicorhinus, Xenobarhus, The of the adduc- Phreatichthys, Garra, Cap- as in predaceous species. insertion

and a Barilius (Barilius, Chelae- tor mandibulae A on the coronoid tostomabarbus) type (A2 3) process only,

To thiops, Engraulicypris, Leptocypris). a certain ex- is, however, a characteristic of predatory types. also accordance with tent, this classification is in eco- The development of premaxillary pedicels, which

distinctions. of which logical Bashora, two species allies strong protrusibility with greater rigidity, is

have been described African of doubt- also as (though very a necessary development in predaceous forms. close the Barilius but ful origin) is apparently to type, The post-orbital jaw articulation which is developed has been studied furtherhere. The table not following in some Barilius species, would be a primitive char-

(Table III) summarises most of the major characters￿ acter (see Schaeffer & Rosen, I.e.); but it is not al-

as well those to as of lied here vertical pertaining feeding, systematic to a jaw suspension (hyomandibular) and ecological nature￿distinguishing the three types and has evidently been secondarily acquired.

defined above. Labeo as Ecologically, the type is highlv specialised Schaeffer & Rosen the feed- towards According to (1961), a phytophageous (microphytophageous) diet;

Teleosts of the ing mechanisms of early Elopid type, of the Barbus1 group, many are facultative feeders,

which the funda- to Cyprinid type is related, were their specialisations not having been carried so far, in

and it reasonable to infer the of them mentally predaceous seems large majority cases, as to restrict to a that this indeed was so in early Cyprinids. In fact, particular diet. Finally, the Barilius type is entirely

the Cyprinidae, like most Teleosts possess a highly carnivorous (predaceous) with corresponding speciali-

kinetic prehensile apparatus which shows some typi- sation of the prehensile mechanism opposed to simpli-

cal the absence of the specialisations￿e.g. ligament fication of the selective apparatus.

characteristic of most other teleost the of patterns types￿ As regards taxonomy the genera studied, the and has been independently derived, probably from findings entirely confirm their validity and besides,

these sub-acanthopterygian ancestors, according to reveal other characters on which further sub-division

authors. The forms had be least of primitive presumably strong- may based, at sub-generically, in some

and this character has them number of ly protractile mouths, though (e.g. Labeo, Barbus). A features, as

been retained reduced well in most recent types, it is in of osteological nature as concerning muscular the forms reveal Labeo some of more specialised (e.g. Laheo, Gar- arrangement, that stands quite apart

ret, Barilius) and strongly modified in others (Cop- from all other African genera (see also Table III); the tostomaharhus). Certainly the most typical character Barhus and Barilius types share many characteristics of this the absence of teeth and which indicative of close affinities. family is consequent are phylogenetical development of a post-branchial masticatory appara- Even though a genus like Garra shows a number of

well all the Labeo-Uke these tus. This is developed in species studied, characters, are probably only due to the dentition close evolution and closest affinities showing most specialisation, in convergent its are accordance with the type of food. The teeth are also quite definitely with fishes of the Barbtts group.

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Table III. Characteristics distinguishing the three fundamental types of African Cyprinidae.

Labeo type Barbus type Barilius type

Stocky forms variable forms elongateforms

and rostral in Well-developed rostrum rostrum some (Garra) no rostrum or rostral groove

groove

mouth Mouth moderately protrusile, inferior, strongly protrusile general- mouth terminal, large, upper jaw

inferior terminal, transverse ly, to not very protractile

Lips thick, papillose lips variable lips absent

Barbels usually reduced barbels mostly well developed barbels absent

Horny cutting edge on jaws horny edge in some (Garra) no horny edge, jaw edge ribbed.

moderate- No premaxillary pedicels premax. pedicels usually premax. pedicels large

ly developed

Interdentary cartilage developed dentarysymphysis generally simple symphysial knob usually well deve-

loped

Mandibular articulation with quadrate, mandibular artic. variable, usually mandible articulates with quadrate

preopercular (& interopercular) with quadrate and preopercular only only Vomero-palatine organ generally ￿ longitudinal pli- palate plicated longitudinally; pa-

cae on palate, but rudimentary pillose pad present in some

organ in some (Barbopsis, Garra)

Pharyngeal pad well-developed, papill- pharyngeal pad variably developed pharyngeal pad poorly developed

ose

Gill-rakers numerous, formingfine sieve gill-raker development variable; gill-rakers usually poorly develop-

usually rough, ￿ adjustable filter ed, few in number

Gill slits largely united to the isthmus, gill slits variable in development gill slits narrowly united to the

isthmus, ￿ restricted

Urohyal flat, broad, not strongly keeled urohyal strongly keeled, not much urohyal strongly keeled, narrow

flattened laterally, except in Garra

Pharyngeal bones relatively small, pharyngeals falciform, relatively Pharyngeals falciform, slender

stocky, ￿ triangular large and strong

Pharyngeal teeth molariform, close-set pharyn. teeth variable, mostly pharyn. teeth reduced in number,

spoon-shaped, with a backwardly pointed, hooked

directed point

Masticatory plate horny, deciduous mastic, plate horny or calcified mastic, plate soft, not cornified

Air-bladder often somewhat reduced air-bladder reduced in some (Garra) air-bladder well developed

Intestine extremely long intestine moderate intestine very short, anterior intes-

tinal bulb large

Adductor mandibulae specialised, inser- adduct. mandib. of a general type, adductor mandibulae very special-

insertion of anterior ised insertion on coronoid tion of A on mandible A 2 & A 3 more ; 2 A 3 3 posterior (A )

process only.

Intermandibularis absent intermandibularis usually present intermandib. mostly present

Geniohyoideus simple geniohy. modified into a protractor geniohy. modified (protr. hy.)

hyoidei

Interhyoideus present interhy. poorly developedor absent interhy. absent

Hyohyoideus lies dorsad to urohyal hyohy. lies ventrad to urohyal hyohy. ventrad to urohyal

Cleithro-pharyngeus profundus absent cleithro-pharyn. prof, present cleithro-pharyn. prof, present

Antero-internal fascium of Levator V antero-int. fascium of lev. V present antero-int. fascium of lev. V present

absent

& Bottom-living species; stayers craw- usually bottom-living; stayers, open-water spp.; sprinters

lers crawlers, some sprinters

(Micro)phytophageous omnivorous/carnivorous carnivorous (predatory)

lack of More detailed research, especially on the anatomy, Lack of time and particularly adequate

and of the material well fresh materialfor investi- physiology ontogeny head region of these (as histological will and for live with fish, certainly answer many questions as regards gation dissection, as specimens and limitations the the finer structure functioning of their feeding which to experiment) imposed on

as nevertheless, I mechanisms and of their taxonomical relationships scope of this work, which will hope,

value. well. prove to be of

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LIST OF ABBREVIATIONS

1 . fascia a. angular lab.V antero-internal of same aabp. attractor arcus branchialis posterior lap. levator arcus palatini

a.bl. air bladder l.j. lateral flange (pharyngeal bone) abm. abdominal muscles l.j. lower jaw

a.c. anterior cartilage (of pharyngeal bone) l.l. lower lip a.d. adhesive disc (outline of) l.r. lamellar ridge adsa. adductor discus suctorius anterior m.b. maxillary barbel

adsp. adductor discus suctorius posterior mes. mesethmoid muscle fibres alv. alveolar area (pharyngeal bones) m.f.

amd. adductor mandibulae m.gr. median groove

m.l. mandibular a.p. anterior process (pharyngeal bone) ligament mouth a.ph. anterior pharynx mo.

art. articular m.p. masticatory process (basioccipital)

a.s. aponeurotic striation m.pap. micro-papillae median as.p. ascending process (pharyngeal bones) m.p.r. palatal ridge

a.sy. anterior symphysis (pharyngeal bones) mpt. metapterygoid

a.t. areolar tissue m.r. median ridge

b.a. branchial arches m.t. enlarged molariform teeth bbr. basibranchial m.v. maxillary valve b.c. buccal cavity m.w. mouth wall bh. basihyal mx.l. maxillary b.m. basement membrane mx. maxillary-coronoid ligament boc. basioccipital mxc.l. maxillary ligament

br. brain mxp.l. maxillary-premaxillary ligament br.r. branchiostegal rays no. nostrils orbit bsph. basisphenoid o. b.v. blood vessel oe. oesophagus

cba. coraco-branchialis anterior op. operculum

cbp. coraco-branchialis posterior op.m. opercular membrane

cbr. ceratobranchial os. os Suspensorium ch. ceratohyal pa. parietal cl. cleithrum pal.pl. palatal plicae

fibres co.f. collagen pap. papillae

cp. cleithro-pharyngeus ph.b. pharyngeal bone

cpp. cleithro-pharyngeus profundus ph.p. pharyngeal pad

cps. cleithro-pharyngeus superficialis ph.t. pharyngeal teeth

coronoid c.pr. process ph.w. pharynx wall

c.t. connective tissue p.k. posterior knob (masticatory plate) d. dentary pi. plicae

el.f. elastic fibres pl.gr. post-labial groove

ep. epithelium (mucosa) pmx.p. premaxillary pedicel

jr. frontal pmx. premaxillary

gh. glossohyal pn.d. pneumatic duct ghy. geniohyoideus pop. preoperculum lamellae g.l. gill p.p. anterior papillose pad

go.c. goblet cells p.ph. posterior pharynx.

g.r. gill rakers p.ph.c. posterior pharyngeal chamber h. heart p.pl. papillose plicae (lips) h.e. cutting horny edge (jaw) p.pr. posterior process (basioccipital) h.h. hypohyal p.r. posterior ridge (separating buccal cavity from hhy. hyohyoideus pharyngeal pad) hm. hyomandibular prsph. presphenoid

h.p. horny plate psph. parasphenoid hy. hyoideus pv.p. postero-ventral process (pharyngeal bone)

ihy. interhyoideus pw.m. pharyngeal wall muscles imd. intermandibularis q. quadrate

intramandibularis retractor inmd. rabdi. arcus branchialis dorsalis inferior

int. intestine rabds. retractor arcus branchialis dorsalis superior

int.b. intestinal bulb r.b. rostral barbel

iop. interoperculum r.f. rostral flap

/. lamellae r.gr. rostral groove levator lab.V. arcus branchialis V ro. rostral bone

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taste bud s.e. smooth epithelium (mouth floor) t.b.

sig.l. sigmoid ligament to. tongue

sk.m. superficial skin muscle ft). (IV, V) transversus ventralis (IV & V)

transverse smx.c. sub-maxillary cartilage tv.r. ridges

so. sub-orbitals tu. tubercles

uh. soc. supraoccipital urohyal

soc.p. supraoccipital process u.j. upper jaw u.l. sop. suboperculum upper lip

sph.o. sphincter oesophagi v. vertebrae

src. subarcualis rectus communis v.a. ventral aorta

st.e. stratified epithelium vo. vomer sthy. sternohyoideus v.ph.p. ventral pharyngeal pad knob stj.k. symphysial vpo. vomero-palatine organ

BIBLIOGRAPHY

Al-Hussaini, A. H., 1949: On the functional morphology Edgeworth, F. H., 1935: The cranial muscles of verte-

tract in to of the alimentary of some fish relation brates. Cambridge Univ. Press.

differences in their feeding. Quart. J. micr. Sc. (Lon- Evans, H. E. & Deubler, E. E., 1955: Pharyngeal don), 90, 109-139 & 323-354. tooth replacement. . . Copeia, 1, 31-43.

Berg, L. S., 1948: Freshwater fishes of the U.S.S.R. 11, Fiebiger, J., 1931: ￿ber den Bau und die Mechanik des

Acad, of Sc. Press, Moscow (4th ed.), 493-846. Karpfenr~ssels. Zeitschr. mikr. anat. Forschg., 27. and The and of Boddeke, R., Slijper, E. J. v. d. Stelt, A., 1959: Fryer, G., 1959: tropic relationships ecology

Histological characteristics of the body musculature of some littoral communities of lake Nyassa. Proc. Zool.

fishes in connection with their mode of life. Koninkl. Soc. London, 132, III, 153-281.

Nederl. Akad. Wetensch., (C) Zool., 62, 5, 576-588. Girgis, S., 1952: The bucco-pharyngeal feeding mechan-

Boulenger, G. A., 1901: Poissons du bassin du Congo. ism in an herbivorous bottom-feeding Cyprinid Labeo

Publ. de l'Etat Ind￿p. du Congo, Bruxelles. horie (Cuv.). J. Morph., 90, 281-315.

- 1907: The Fishes of the Nile, in "Zoology of Egypt". ￿ On the anatomy and histology of the alimentary tract

of an Publ. Egypt. Gov., London. herbivorous bottom-feeding Cyprinid ... J. Morph.,

Brown, M. E., 1957: The Physiology of Fishes. Acad. 90, 317-362.

Press, New York, vol. 1, 109-154; vol. II, 187-207. Gosse, J. P., 1956: Dispositions speciales de l'appareil

Carrie, M., 1937: Note sur l'appareil digestif et la branchial des Tilapia et des Citharinus. Ann. Soc. R.

digestion de la tanche ((Tinea tinea), Bull. Soc. Zool. Zool. Belg., LXXXVI, 2, 303-308.

Fr., 62, 277-280. Grass￿, P. P., 1958: Traite de Zoologie. XIII, (2), pp.

Chu, Y. T., 1935: Comparative studies on the scales and 929-934 and 1248-1302; (3), 2295-2300.

on the pharyngeals and their teeth in chinese Cypri- Greenwood, H. Ph., 1958: The fishes of Uganda. Uganda

nids . . . Biol. Bull. St. Johns Univ., Shanghai, 2, 1-225. Soc. Publ., Kampala, 49-70.

Curry, E., 1939: The Histology of the digestive tube of Gregory, W. K., 1933: Fish skulls. Trans. Am. Phil. Soc.

the Carp. J. Morph., 65, 53-78. Philad., XXIII, 2, 189-194.

Daget, J., 1954: Les poissons du Niger sup￿rieur. M￿m. Haempel, O., 1909: Die Schlundknochenmusculatur der

I.F.A.N., 36, 174-218. Cypriniden und ihre Function. Zool. Jahrb. (Abt. Anat.), conformation du David, L., 1937: La museau chez un 27, 95-101.

petit Cyprinide africain. Coptostomabarbus wittei Heckel, J. J., 1843: Die fische Syriens. Schwcizerbartsche

David & Poll. Rev. Zool. Bot. Afr., 30, 1, 1-18. Verlagshandlung, Stuttgart.

Day, F., 1889: Fishes (I and II), in: Fauna of British Heuts, M. J., 1951: Ecology, variation and adaptations of

India. Taylor & Francis (London), 213-367. the blind african cave fish Caecobarbus . . . Ann. Soc.

Dietz, P. A., 1912: Vergelijkende anatomie van de kaak Roy. Zool. Beige, 82, 2, 155-230.

The en kieuwboogspieren der Teleostei. (Proefschrift). Uitg. Holstvoocd, C, 1961: importance of the Retractores

E. Ydo, Leiden. Arcuum Branchialium for the Classification of teleo-

49-50. Dobben, W. H. van, 1935: ￿ber den Kiefermechanismus stean Fishes. Bull. Aq. Biol., 2, 15,

der Knochenfische. Arch. N￿erl. Zool., II, 1, 27-31. Hoppe, R., 1894: Untersuchungen ~ber den Kauapparat

Dorier, A. & Belon, G., 1952: Sur l'organe palatin des der Cyprinoiden (Dissertation). A.Th. Engelhardt Ed.,

Cyprinid￿s. Trav. Lab. Hydrob. Pise. Grenoble, 44, Leipzig, 35 pp.

47-60. Hora, S. L., 1922: Structural modifications in the fishes

Dottrens, E., 1951: Les poissons d'eau douce. /, Paris, of mountain torrents. Rec. Ind. Mus., 24, 1, 31-61.

torren- 17-70. ￿ 1930: Ecology, bionomics and evolution of the

Downloaded from Brill.com10/05/2021 03:05:48PM via free access FEEDING MECHANISMS OF AFRICAN CYPRINIDAE 35

tial fauna of fishes in relation to studies. Part VII, with special reference to the organs phylogenetic

attachment. Phil. Trans., B￿ 218. (Cyprininae), Acta Zool., 36, 199-242.

Sarbahi, D. S., 1940: The alimentary canal of Labeo Hubbs, C. L., 1941: The relation of hydrological con- rohita Soc. 2, ditions to speciation in Fishes. (Symp. Hydrob.). Univ. (Ham.). J. Roy. As. Bengal, (Sc) 5,

of Wisconsin Press, 182-195. 87-116.

Schaeffer, B. & Rosen, D. E., 1961: Major adaptive Maltzan, Grafin v. R., 1935: Zur Ern￿hrungsbiologie levels in the evolution of the actinopterygian feeding und Physiologie des Karpfens. Zool. Zentr. Abt., 3, 55, mechanisms. Am. 191-218. Zool., 7, 2, 187-204. Suvorov, E. K., 1959: Algemeine Fischkunde. Veb. Mcvay, J. A. & Kaan, H. W., 1940: On the digestive Deutsch. Verl. Wiss., Berlin, 128-131. tract of Carassius auratus. Biol. Bull., 78, 53-67. Suyehiro, Y., 1942: A study on the digestive system and Pictet, A., 1909: Contributions a l'￿tude histologique du feeding habits of fish. Japan. J. Zool., 10, 1-303. tube digestif des poissons Cyprinoides. Rev. Suisse Takahasi, N., 1925: On the homology of the cranial Zool., 17, 1-76. muscles of the Cypriniform fishes. J. Morph. & Phy- S. S. 1956: Some Plessis, du, adaptations of the genera siol., 40, 1-109. Barbus and Varicorhinus, 2nd Symposium Afr. Hydr. Thtlo, O., 1920: Das Maulspitzen der Fische, Biol. & Inland Fisheries, CSA/CCTA, Publ. 25, 85-87. Zentralbl., 40, 216-238. Poll, M., 1953: Poissons non-Cichlidae. Expl. Hydrob. Weber, M. & de Beaufort, L. F., 1916: The fishes of

L. Tang., I. R. Sc. N. B., 771, 5A, 74-116. the Indo-Australian Archipelago, (Cyprinoidea).. III,

1959: Recherches sur la faune de la ichthyologique Leiden, 43-235. du Stanley-Pool. Ann. Mus. R. Zool. region C.B., (8￿), Zander, E., 1903: Studien ~ber das Kiemenfilter bei

71, 150-171. S~sswasserfischen. Zeitschr. wiss. Zool., Leipzig, 75,

Ramaswami, L. S., 1955: The skeleton of Cyprinoid 233-257.

Downloaded from Brill.com10/05/2021 03:05:48PM via free access Plate 1.

a. Head of Laheo lineatus (lateral view)

showing rostral flap and retracted infe-

rior mouth bordered by thick lips, (x 2)

b. Head of Labeo

niloticus (median

longitudinal section)

showing the course

of the buccopharyn-

geal cavity, (x 2)

Downloaded from Brill.com10/05/2021 03:05:48PM via free access c. Mouth of Labeo variegatus (ventral view) cut to show open lower jaw, horny cutting edges and papillose plicae on lips, (x 4)

d. Palate of L. variegatus, showing vomero- palatine organ and pharyngeal pad. (x 4) Downloaded from Brill.com10/05/2021 03:05:48PM via free access Plate 11.

a. Vomero-palatine organ of

Labeo lineatus on anterior pal-

ate (ventral view), (x 6)

c. Dorsal pharyngeal

pad of L. lineutus (ventral view) show- anterior ing papillae, ridge and median

groove, (x 6) Downloaded from Brill.com10/05/2021 03:05:48PM via free access h. 2nd branchial arch of L. Uneatus (supe- rior view) showing gill-rakers and tiny lat-

eral projections, (x 6)

d. Right pharyngeal bone of L. Uneatus (supe-

rior view) showing molariform grinding denti-

tion, (x 6)

Downloaded from Brill.com10/05/2021 03:05:48PM via free access Plate III.

a. Head of Labeo variegatus with mouth protruded, show- ing papillose lips and ros- trum.

b. Head of Labeo lineatus, showing bones and musculature of the mouth (semi- diagrammatic).

outline of bones, cartilage, etc.

outline of A., lying under A,. outline of A.j lying under A., and Aj.

Downloaded from Brill.com10/05/2021 03:05:48PM via free access c. Head of L. variegatus, showing

bones and musculature of the

mouth.

d. Lower pharyngeals of L. {mea- tus (supero-posterior view) show- ing teath, left half of upper pha- ryngeal bone and masticatory musculature (semi-diagrammatic).

Downloaded from Brill.com10/05/2021 03:05:48PM via free access Plate IV.

linea- a. Lower pharyngeals of Labeo

tus (ventral' view) showing mastica-

tory muscles.

h. Left pharyngeal bone of L. tineatus

(lateral view) show-

ing musculature, outline of pharyn-

geal pad and upper pharyngeal bone.

Downloaded from Brill.com10/05/2021 03:05:48PM via free access c. Portion of left gill arch of Carra congoensis, show-

and of lamellae. ing gill-rakers transverse ridges the gill

J. Mouth of Garru dembeensis (ventral view) showing the lower jaw articulation and the adhesive disc muscles.

Downloaded from Brill.com10/05/2021 03:05:48PM via free access of Labeo lineatus a. Vomeropalatine organ (transverse

its finer structure. (10 Azan) .section) showing //,

h. Palate of Garni dembeensis, showing fringed and upper lip, palatal plicae, pharyngeal pad horny masticatory plate, (x 4)

Downloaded from Brill.com10/05/2021 03:05:48PM via free access Plate V.

c. Pharyngeal hones of G. dembeensis (antero-

superior view) showing hooked teeth, (x 12)

d. Head of Barbas altianalis, showing strongly protrusile mouth, (x 1%)

Downloaded from Brill.com10/05/2021 03:05:48PM via free access l'lale VI.

Head a. of Barbw altlanalis (ven-

tral view) showing interior month and throat musculature, (x 2)

lon- b. Palate of Barbus holotaenia, showing

gitudinal plicae and pharyngeal pad. (x 2)

Downloaded from Brill.com10/05/2021 03:05:48PM via free access c. Branchial cavity of B. altianalis showing the gill- rakers, (x 2)

d. Isolated branchial arch of B. altianalis (superior view) showing papillose projections the on gill- rakers, (x 4)

Downloaded from Brill.com10/05/2021 03:05:48PM via free access Plate VII.

bones of a. Pharyngeal Bar- bus tropidolepU (antero-supe- rior view) showing molari- form dentition, (x 2%)

/;. Lower pharyngeals of Barbus al-

tianalis (antero-superior view) show-

ing spoon-shaped teeth and alveolate

lateral flange, (x 2V2)

Downloaded from Brill.com10/05/2021 03:05:48PM via free access c. Masticatory plate of B. altianalis

(ventral view) showing the posterior

knob and undulated masticatory sur-

face, (x 5)

d. Transverse sec-

tion of the head of

Barbus pleuropholis

(anterior orbit re-

gion,) showing large plicae of the mucosa and numerous goblet

Haema- cells. (10 /(, toxylin-eosin)

Downloaded from Brill.com10/05/2021 03:05:48PM via free access a

Downloaded from Brill.com10/05/2021 03:05:48PM via free access b c

Flute VUL

the anterior orbital of Barbus a. Transverse section of region pleuropholis, showing the more detailed histological

structure of the buccal lining (10 tt, Ilaematoxylin-eosin).

b. Anterior snout region of B. pleuropholis (transverse section), showing taste buds and stratified epithelium of the buccal mucosa (10 u, Weichert-von Gieson).

of c. Anterior pharyngeal region B. pleuropholis (transverse section), showing the structure of the pharyngeal pad.

(10 /u, Haematoxylin-phloxin)

Downloaded from Brill.com10/05/2021 03:05:48PM via free access Plate IX.

a. Head of Barbus nedgia (R~pp., 1837)

(modified, after Boulenger, 1907) showing large, lobed lips.

b. Head of Barhus altianalis, showing bones and musculature of the mouth (semi-diagrammatic).

Downloaded from Brill.com10/05/2021 03:05:48PM via free access c. Left pharyngeal bone of B. altianalis (lateral view) showing masticatory muscles.

Downloaded from Brill.com10/05/2021 03:05:48PM via free access of Barbus a. Pharyngeal pad pleuropholis (longitudinal sec- tion) showing the criss-cross muscle fibres (fO it, Azan)

b. Palate of Varicorhinus tanganicae, showing

large median ridge, feeble development of plicae,

pharyngeal pad and masticatory plate, (x 2)

Plate X.

Downloaded from Brill.com10/05/2021 03:05:48PM via free access C. Lower pharyngeal bones of V. tanganicae

(antero-superior view) showing the close-set teeth, (x 6)

d. Head of Coptostomabarbus

mouth wittei with cut open, show- ing the tongue. (Note vertical

stance of mouth.) (x 8)

Downloaded from Brill.com10/05/2021 03:05:48PM via free access Plate XL

of a. Head Barilius chiistyi, showing large,

terminal mouth and symphysial knob, (x 2)

h. Palate of Barilius moorei, showing

ridged jaw epithelium, anterior papil-

of base lose pad, row papillae along

of maxillary valve (right half cut a- way) and longitudinal plicae, (x 3)

Downloaded from Brill.com10/05/2021 03:05:48PM via free access of B. c. Pharyngeals moorei (antero-superior view) showing sharp, hooked teeth, (x 6)

d. Head of Leptocypris modestus showing fully opened, small, sub-inferior

mouth, (x 4)

Downloaded from Brill.com10/05/2021 03:05:48PM via free access Plate XII.

a. Head of Barilius christyi, showing ven-

tral musculature of mouth and anterior pharynx.

b. Head of ￿. christyi, showing bones and musculature of the mouth.

c. The same, and A,a (partly) removed, showing the deeper musculature.

Downloaded from Brill.com10/05/2021 03:05:48PM via free access b

c

Downloaded from Brill.com10/05/2021 03:05:48PM via free access