A PHYLETIC STUDY OF THE LAKE TANGANYIKA CICHLID 
GENERA ASPROTILAPIA, ECTODUS, LESTRADEA, 
CUNNINGTONIA, OPHTHALMOCHROMIS, AND 
OPHTHALMOTILAPIA 
KAREL F. LIEM' 
CONTENTS 
Abstract 191 
Introduction 191 
Materials and Methods 192 
Osteological Aspects of Ectodus 193 
Myological Aspects of Ectodus 195 
Comparative Osteology 197 
Comparative Myology 203 
Phyletic Analysis 205 
Acknowledgments 212 
Abbreviations 212 
Literature Cited 213 
Abstract. On the basis of comparative osteology 
and myology, Asprotilapia, Ectodus, Lestradea, 
Cunningtonia, Ophthalmochromis, and Ophthal- 
motilapia of Lake Tanganyika are hypothesized to 
be members of a monophyletic lineage of cichlid 
fishes. All members share the following suite of 
characters: (1) the entopterygoid is widely separat- 
ed from the palatine; (2) the posterior and dorsal 
margins of the palatine form a 90° angle; (3) the 
slender hyomandibula has a long symplectic pro- 
cess and a very reduced hyomandibular flange; (4) 
the anterior margin of the pterosphenoid is 
notched; (5) the vertical depth of the metapterygoid 
is shallow; (6) the operculum has a distinct auricular 
process; (7) the transversus dorsalis muscle is re- 
duced; and (8) the obliquus posterior muscle is en- 
larged. These characters are considered specialized 
when compared with the accepted generalized 
mori^hology oi Astatotilapia. The phyletic relation- 
ships of this lineage are documented by synapo- 
morphies that distinguish subunits of decreasing 
levels of universality within the assemblage. As- 
protilapia represents a highly specialized branch 
with six major skeletomuscular specializations. The 
remaining five genera are pictured as a second lin- 
' Museum of Comparative Zoology, Harvard Uni- 
versity, Cambridge, Massachusetts 02138. 
eage, of which Ectodus is the most generalized tax- 
on. On the basis of recency of common descent, 
Ophthalmochromis is synonymized with the genus 
Ophthalmotilapia. Although there is no doubt that 
the Ophthalmotilapia lineage has undergone ex- 
tensive morphological radiation in both skull struc- 
ture and dentition, the data on morphology, func- 
tion, trophic ecology, and behavior of this and other 
cichlid lineages have failed to establish unequivo- 
cally that the morphological radiation is also adap- 
tive. The morphological and functional pattern in 
this lineage reinforces the paradox that morpholog- 
ically and phylogenetically most specialized cichlid 
taxa are not only remarkable specialists but also 
jacks-of-all-trades. 
INTRODUCTION 
The precise phylogenetic interrela- 
tionships of the endemic cichHds in Lake 
Tanganyika are still unknown (e.g., Fryer 
and lies, 1972: 507). Essentially the 
problem is to distinguish groups that are 
true, hierarchically evolved sister groups 
showing increasing specialization or apo- 
morphy, from groups that are gradal as- 
semblages of polyphyletic ancestry 
(Greenwood, 1974, 1979). Liem and 
Stewart (1976) have shown that the lepi- 
dophagous cichlids of Lake Tanganyika 
represent a monophyletic lineage. Re- 
cently Liem (1979) has postulated that 
because of the basic homogeneity in spe- 
cialized morphology and function, the in- 
vertebrate picking cichlids of Lake Tan- 
ganyika must have originated from a 
common ancestor. Greenwood (1979) has 
synonymized Limnotilapia with Simo- 
Bull. Mus. Comp. Zool., 149(3): 191-214, Februar>-, 1981 
192 Bulletin Museum of Comparative Zoology, Vol. 149, No. 3 
chromis to show the close phyletic rela- 
tionships of two genera previously pic- 
tured as belonging to two different 
lineages (Fryer and lies, 1972: 507). A 
complete analysis of phyletic relation- 
ships for the endemic cichlids is hin- 
dered because of an apparent absence of 
synapomorphic features which would en- 
able one to build up the various levels of 
relationship, and a phyletic analysis of 
cichlids from other lakes and rivers. This 
paper is part of a series dealing with the 
establishment of monophyletic lineages. 
Such an attempt represents a first step to- 
ward the ultimate goal of interrelating 
the different lineages on a sister group 
basis. 
This paper deals with six endemic gen- 
era of Lake Tanganyika: Asprotilapia, 
Boulenger, 1901; Ectodus, Boulenger, 
1900; Lestradea, Poll, 1943; Cunningto- 
nia, Boulenger, 1906; Ophthalmotilapia, 
Boulenger, 1901; and Ophthalmochro- 
mis. Poll, 1956. Except for Ectodus, this 
assemblage is characterized as predomi- 
nantly herbivorous, inhabiting rocky hab- 
itats of Lake Tanganyika down to a depth 
of 15 m. Ectodus is especially abundant 
in shallower and sandy habitats. With the 
exception of Ectodus descampsi, all 
members of the group possess long intes- 
tinal tracts (2.5-6 times the standard 
length) and exploit filamentous and uni- 
cellular algae, diatoms, crustaceans, and 
insect larvae as food sources. Based on 
comparative osteological and myological 
data, I am presenting a hypothesis that 
the assemblage is monophyletic, with 
Asprotilapia as a very specialized form, 
and Ectodus and Lestradea as the least 
specialized representatives. 
In this study only a limited number of 
functional data have been gathered from 
Lestradea and Ophthalmotilapia. How- 
ever, much information from other cich- 
lids (Liem, 1978, 1979, 1980) can be ap- 
plied to this lineage in determining the 
nature and possible evolutionary direc- 
tion of the character complexes. A pro- 
visional phylogenetic scheme is pre- 
sented as a hypothesis, with each branch 
defined by its unique morjihological spe- 
cializations. 
MATERIALS AND METHODS 
Osteological studies are based on aliz- 
arin preparations and some dried skele- 
tons. Osteological nomenclature follows 
Liem and Stewart (1976) and Barel et at. 
(1976). The myology has been studied 
from formalin fixed specimens, which are 
stored in 70% ethyl alcohol. With very 
few exceptions the nomenclature of Win- 
terbottom (1974) and Anker (1978) is fol- 
lowed. All drawings were made by 
means of the Wild-M5 camera lucida. 
The following specimens from the Brit- 
ish Museum (BM) and the Museum of 
Comparative Zoology (MCZ) have been 
studied: 
Asprotilapia leptura BM 1906.9.6.157 
Asprotilapia leptura BM 671 (dried skeleton) 
Aulonocranus dewindti BM 1960.9.30.4642-4656 
Aulonocranus dewindti MCZ 49305 
Callochromis macrops BM 1960.9.30.2821-2823 
Callochromis melanostigma BM 1960.9.30.2845- 
2859 
Callochromis pleurospilus MCZ 49280 
Cardiopharynx schoutedeni BM 1960.9.30.1574- 
1615 
Cunningtonia longiventralis MCZ 49243 
Cunningtonia longiventralis BM 1960.9.30.1912- 
1919 
Ectodus descampsi BM 1961.11.22.113-119 
Grammatotria lemairei MCZ 49277 
Grammatotria lemairei BM 1960.9.30..3317-3330 
Astatotilapia {"Haplochromis") burtoni BM 
1960.9.30.2415-2433 
Lamprologus elongatus BM 1960.9.30.6790-6793 
Lamprologus elongatus MCZ 49251 
Lamprologus moorei MCZ 49245 
Leptochromis calliurus BM 1960.9.30.3351-3353 
Lestradea perspicax perspicax BM 1960.9.30.1468- 
1484 
Limnochromis auritus BM 1960.9.30.1981-1985 
Ophthalmochromis nasutus MCZ 49232 
Ophthalmochromis ventralis BM 1960.9.30.1689- 
1694 
Ophthalmochromis ventralis MCZ 49232 
Ophthalmotilapia hoops BM 1960.9.30.1720-1724 
Ophthalmotilapia hoops BM 1960.9..30. 1716-1718 
Sarotherodon nilotica MCZ 49312 
Trematocara unimaculatum BM 1961.11.22.519- 
528 
Trematocara unimaculatum MCZ 49262 
Tylochromis polylepis BM 1960.9.30.109-113 
Xenotilapia ornatipinnis MCZ 49266 
Xenotilapia sima BM 1961.11.22.208-211 
CiCHLiD Phylogeny* Liem 193 
Figure 1. Dorsal aspect of the neurocranium. A, Ectodus descampsi; B, Lestradea perspicax; C, Asprotilapia leptura; 
D, Ophthalmotilapia ventralis; E, Ophthalmotilapia boops. 
9,t^P^Tnn,^!i^^ ASPECTS ^ ^i^^^^^^ (Liem and Osse, 1975; Barel 
OF ECTODUS ^^ ^i ^ 1^1^), such as the somewhat de- 
The neurocranium of Ectodus retains curved dorsal profile to the preorbital 
many primitive features found in Asia- face and the high cranial vault. However, 
totilapia ("Haplochromis") burtoni and the ethmovomerine region is relatively 
194 Bulletin Museum of Comparative Zoology, Vol. 149, No. 3 
pa 
pt 
ps 
soc 
eoc 
boc 
sph po 
Figure 2. Lateral aspect of the neurocranium. A, Ectodus descampsi; B, Lestradea perspicax; C, Cunningtonia lon- 
giventralis; D, Ophthalmotilapia boops; E, Ophthalmotilapia ventralis; F, Asprotilapia leptura. 
CiCHLiD Phylogeny* Liem 195 
long and is dorsally differentiated into a large, widely separated ascending pro- 
well-developed rostral fossa, which is cesses of the dentary and anguloarticular. 
made up by the ethmoid and the de- The ascending process of the anguloar- 
pressed anteromedial wings of the fron- ticular is expanded posteriorly to form an 
tals (Fig. lA:e,f). The ethmoid is sutur- adductor fossa, serving as the insertion 
ally united with the ascending processes site of the A2 part of the adductor man- 
of the vomer and with the lateral eth- dibulae muscle complex (Fig. 6A:am2). 
moids (Fig. 2A:e,pf). The long axis of the The size, shape, and configuration of 
basioccipital makes a 60-70° angle with the opercular apparatus (Fig. 5A) do not 
that of the parasphenoid (Fig. 2). Both the differ from those of generalized cichlids. 
basioccipital and parasphenoid bones In Ectodus the posterodorsal corner of 
contribute to the formation of a promi- the operculum is raised to form an auric- 
nent pharyngeal apophysis, which is ular process, which is not encountered in 
therefore of the "Haplochromis" type, generalized cichlids. 
Another specialization can be found in Of the well-developed five or six cir- 
the pterosphenoid in the form of a deep cumorbitals, the large lacrimal is distinct- 
notch in the anterior margin of the ptero- ly shaped and possesses six sensory pores 
sphenoid (Fig. 2A:pts). The saccular bul- (Fig. 5A:la). The ventral margin is con- 
la is greatly enlarged (Figs. 2A, 3A). vex, while the posterodorsal margin is 
Morphologically the suspensory appa- concave. The anterodorsal margin is 
ratus of Ectodus deviates from the more straight. Anteriorly the lacrimal ends in 
generalized configuration of that in As- an anteriorly directed angular process. 
tatotilapia hurtoni (Fig. 4A; Liem and The branchial skeleton is not de- 
Osse, 1975). The hyomandibula is slen- scribed here because the elements retain 
der with an elongate symplectic process a relatively generalized condition and do 
and a much reduced flange area below not contribute to the solution of phylo- 
the anterior condyle. The two hyoman- genetic relationships in this group of 
dibular condyles are distinctly separated, cichlids. 
while the symplectic process is connect- 
ed to the metapterygoid, which is a char- %As/r\i n^r-ir^Ai Aooirr^-ro r\c 
acteristically shallow bone. Ihe reduced p_.^_^.._ 
entopterygoid is separated from both the 
ectopterygoid and the palatine. Half of The lateral head muscles of Ectodus 
the entopterygoid's lateral surface is (Fig. 6A) retain their unspecialized con- 
overlapped by the quadrate. The palatine dition in respect to topography, configu- 
bone is unusual in having its posterior ration, and structure. Thus the descrip- 
and dorsal border meet at a 90° angle, tion of the head muscles of As^afoff/apia 
Posteriorly the suspensory apparatus is elegans by Anker (1978) also applies to 
delineated by a large preoperculum of those of Ectodus. The adductor man- 
which the outer rims of the horizontal dibulae complex (Ai, A2, A3, A^) of Ec- 
and vertical limbs make a distinct 90° an- todus is identical to that of A. burtoni, 
gle. The anterior border of the suspen- except that the muscle fibers in the for- 
sory apparatus formed by the ectoptery- mer are considerably more elongate, a 
gold and the palatine is oblique, making feature which is probably correlated with 
a 60° angle with the horizontal plane. the much larger orbit and the longer and 
The jaw apparatus in Ectodus (Fig. 4A) more shallow suspensory apparatus. The 
possesses a generalized premaxilla re- levator arcus palatini in Ectodus (Fig. 
sembling that of Astatotilapia burtoni, 6A:lap) is less voluminous than in A. bur- 
hut the maxilla has a prominent earlike toni (Liem and Osse, 1975). Because the 
postmaxillary process. The elongate, hyomandibular flange zone is much more 
slender mandible is characterized by restricted, most of the fibers insert on the 
196 Bulletin Museum of Comparative Zoology, Vol. 149, No. 3 
muscular process of the metapterygoid. tion of pharyngol^ranchials 2 and 3, 
The other lateral head muscles have not inserting on both bones. Levator internus 
undergone any specialization and will not 2 (or posterior) passes ventrocaudally 
be described here (Fig. 6A:aap,do,lo,ep). along the outer margin of the second 
The ventral muscles of the head of Ec- pharyngobranchial to insert on the third 
todus (Fig. 7A:gh,sh) do exhibit several pharyngobranchial near the junction of 
specializations if compared with those of the third and fourth epibranchials. The 
A. hurtoni and A. elegans. The left and levatores interni are equally developed, 
right geniohyoideus anterior (Fig. cylindrical muscles. The levatores exter- 
7A:gha) are clearly separated, cylindrical ni 1-3 are relatively slender, straplike 
muscles, each attaching to the dentary muscles running caudoventrally to insert 
near the mandibular symphysis ventral to on the dorsal aspects of the epibranchials 
the small parallel-fibered intermandibu- 1-3 respectively. As in all cichlids (Liem, 
laris. A transverse myosept interrupts the 1974), the fourth levator externus is the 
fiber course of the geniohyoideus just an- dominant component of the externi com- 
terior to the hyoid symphysis. From the plex, lying in a parasagittal plane. Its fi- 
transverse myosept, the geniohyoideus bers pass ventrally to converge on the 
posterior runs laterally to attach to the lat- muscular process of the lower pharyngeal 
eral aspect of the hyoid above the first 2 jaw. The insertion appears as a complex 
branchiostegals. The hyohyoideus com- mixture of muscular and tendinous ele- 
plex (Fig. 7A:hhs,hhi) lies between the ments. Only a few lateral fibers attach to 
hyoids, the branchiostegals and the me- the dorsal side of the fourth epibranchial 
dial aspect of the opercular apparatus, by means of an aponeurotic plate. 
We may distinguish three parts: (1) the The obliquus posterior muscle (Fig. 
hyohyoideus inferior (Fig. 7A:hhi) aris- 8A:obp) is characteristically a highly de- 
ing from the anteroventral corner of the veloped muscle in Ectodus originating 
hyoid ramus runs caudally and slightly from the dorsal surface of the fourth epi- 
lateral to insert on the first to fourth bran- branchial. From this expanded origin, the 
chiostegal rays by splitting into four fibers run laterally and caudoventrally 
heads; (2) the hyohyoideus superior (Fig. converging on the muscular process of 
7A:hhs) runs between the rays and the the lower pharyngeal jaw. The insertion 
medial aspect of the gill cover; and (3) site is medial and ventral to that of the 
the hyohyoideus transversus (Fig. 7A:hht) fourth levator externus. 
runs between the first left and first right Joining the insertion sites of the fourth 
branchiostegals. The hyohyoideus trans- levator externus and obliquus posterior 
versus is much better developed than in muscles on the muscular process of the 
A. hurtoni. lower pharyngeal jaw is the fifth adductor 
In the branchial musculature, the ven- muscle (Fig. 8A:ad). This spindle-shaped 
tral muscles correspond with those of muscle attaches to the medial surface of 
more generalized cichlids (e.g., Astatott- the dorsal end of the shank of the fourth 
lapia elegans. Anker, 1978) with respect epibranchial adjacent to its articulation 
to topography, structure, attachment sites ^i^h ^^e fourth ceratobranchial. From 
and shape. Therefore, the description ^j^^^ P^i^t, the muscle runs ventrally to 
here will be focussed mainly on the dor- 1^^ muscular process, to which it attaches 
1 1 /!?• 7 A QA\ laterally and posteriorly to the insertion 
sal muscles (rigs. <A, oA). •, c .\ r .^.v i • . 
'' ' ' site of the fourth levator externus. 
Both the levatores externi and interni j^ye two transversi dorsales muscles in 
(Figs. 7A, 8A:le,li) originate from the Ectodus (Fig. 8A:tda,tdp) have under- 
muscular process of the prootic. The le- gone a reduction as compared with those 
vator internus 1 (or anterior) runs medi- of Astatotilapia elegans (Anker, 1978). 
ally and ventrocaudally towards the junc- Basically, the transversi dorsalis anterior 
CiCHLiD Phylogeny • Liem 197 
muscles run between the second pha- trally to insert musculously on the pos- 
ryngobranchials and the second epibran- terodorsal surfaces of both the third and 
chials. The drastically reduced transver- fourth pharyngobranchials. 
sus dorsalis posterior is a small, straplike Three ventral muscles, the pharyngo- 
muscle which runs between the left and hyoideus and the pharyngocleithralis ex- 
right fourth epibranchials. The fibers run ternus and internus, play an important 
without interruption between the two at- role in the operation of the lower pharyn- 
tachments. As in more generalized cich- geal jaw (Liem, 1974, 1978). Although 
lids, the transversus dorsalis anterior, al- none of the three muscles (Fig. 
though reduced in Ectodus, is 7A:ph,pci,pce) exhibits morphological 
differentiated into four heads (Anker, specializations which can be used in a 
1978). The posterior head (M. transversus phylogenetic analysis, they will be brief- 
epibranchialis 2 pars dorsalis) arises mus- ly described as a basis for future, more 
culously from the dorsal surface of the functionally focussed studies. As in most 
anterior fork of the second epibranchial cichlids, the fibers of the pharyngohyoi- 
and runs medially over the second pha- deus are interrupted by an aponeurotic 
ryngobranchial towards a large aponeu- sheet halfway along the length of the 
rosis. Very closely associated with the muscle. Anteriorly, the muscle attaches 
posterior head is a more ventrally located to the urohyal. Near this insertion site, 
component (M. transversus epibranchia- the left and right pharyngohyoideus 
lis 2 pars ventralis) with its attachment to merge inseparably into one unit. Poste- 
the junction of the second pharyngobran- riorly, the muscle fibers blend into a 
chial and second epibranchial and con- strong tendon attached to the lateral sur- 
necting with the median aponeurosis, face of the anteroventral portion of the 
The third head (M. transversus pharyn- lower pharyngeal jaw. The pharyngo- 
gobranchialis 2) is the anterior one, run- cleithralis externus arises from the an- 
ning between the rostromedial surfaces terolateral surface of the cleithrum from 
of the left and right pharyngobranchials. nearly the ventral tip and dorsally until 
Finally, the fourth head (M. cranio-pha- about one-third of its vertical depth, 
ryngobranchialis 2) arises from the neu- From this origin, the fibers run in a par- 
rocranium just anterior to the articulation allel fashion dorsally and slightly ante- 
with the first pharyngobranchial, and riorly converging on an aponeurotic sys- 
runs posterolaterally and ventrally to in- tern which merges with the insertion 
sert on the lateral edge of the anterior as- tendon of the pharyngohyoideus. How- 
pect of the second pharyngobranchial. ever, a subdivision of this aponeurotic 
The obliquus dorsalis muscle (Fig. system takes up a more lateral course to 
8A:od) originates from the area lateral to attach on the fourth epibranchial. The 
the pharyngeal apophysis of the third pharyngocleithralis internus originates 
pharyngobranchial and runs caudolater- from a fossa to a point about midway on 
ally to insert on both the dorsal aspect of the vertical depth of the cleithrum; its fi- 
the third epibranchial just medial to the bers run anteroventrally to converge on 
insertion site of the third levator externus a tendon which inserts on the lower pha- 
and the anterodorsal aspect of the fourth ryngeal jaw just medial and posterior to 
epibranchial. the insertion site of the pharyngohyoi- 
The large retractor dorsalis muscle deus muscle. 
(Fig. 8A:rd) runs parasagittally close to 
the medial plane. Its extensive origin is COMPARATIVE OSTEOLOGY 
irom the exoccipital, the vertebral bodies 
of the first three vertebrae, and the Having outlined the main morpholog- 
apophysis of the third vertebra. From ical features of the most generalized rep- 
these points, the fibers run anteroven- resentative, i.e., Ectodus, we can consid- 
198 Bulletin Museum of Comparative Zoology, Vol. 149, No. 3 
Figure 3. Ventral aspect of the left half of the neurocranlum. A, Ectodus descampsi; B, Lestradea perspicax; C, As- 
protilapia leptura; D, Ophthalmotilapia ventralis; E, Ophthalmotilapia boops. 
CiCHLiD PhylogenY' Liem 
199 
er the anatomy of the other members of 
the assemblage. The comparative de- 
scription will not be a comprehensive 
one. Instead, emphasis will be placed on: 
(1) features that deviate from those found 
in Ectodiis; (2) structural specializations 
characterizing each genus; and (3) mor- 
phological elements which can be used 
to interrelate the different lineages on a 
sister group basis. 
Neurocranium (Figs. 1, 2, 3). The neu- 
rocranium of Lestradea is identical to 
that of Ectodiis except for a somewhat 
shorter ethmovomerine complex (Fig. 
2B). In Cunningtonia the ethmovomer- 
ine complex is distinctly shorter, while 
the basioccipital is excluded from the 
pharyngeal apophysis (Fig. 2C). The eth- 
movomerine region in Ophthalmotilapia 
is greatly abbreviated so that the prefron- 
tal is vertically oriented. The neurocrania 
of Ophthalmotdapia and Ophthalmo- 
chromis resemble each other very closely, 
both having enlarged sensory canals and 
foramina. As in Cunningtonia, the basi- 
occipital is excluded from the pharyngeal 
apophysis (Fig. 3C,D,E). However, in 
Ophthalmochromis the abbreviation of 
the ethmovomerine region is much less 
pronounced, while the enlargement of 
sensory canals and foramina is much 
greater. Ophthalmochromis and 
Ophthalmotilapia differ in the orienta- 
tion of the ventral process of the basi- 
sphenoid, being vertical in the latter and 
oblique in the former (Fig. 2:bs). The 
most specialized neurocranium is repre- 
sented in Asprotilapia: the ethmovomer- 
ine region is elongate with the ethmoid 
in an almost horizontal position; the lat- 
eral ethmoids are enlarged, forming pro- 
nounced preorbital processes; the inter- 
orbital width is much reduced; the orbit 
is greatly enlarged; and the sensory ca- 
nals and foramina are reduced in size. 
Opercular apparatus (Fig. 5). The 
opercular apparatus of all members of 
this lineage conforms with that of Ecto- 
diis. 
Suspensory apparatus (Fig. 4). The de- 
scription of the suspensory apparatus for 
Ectodiis also applies to the other five 
genera of this lineage. However, in Cun- 
ningtonia the palatine is further special- 
ized by the development of a posteriorly 
directed slender process at the postero- 
dorsal corner. Although the vertical 
depth of the suspensorium at the level of 
the metapterygoid is characteristically 
shallow for all members of this lineage, 
the feature is least developed in 
Ophthalmotilapia and most pronounced 
in Cunningtonia. Cunningtonia also pos- 
sesses a very elongate and nearly hori- 
zontal symplectic, and the horizontal 
limb of the preoperculum is longer than 
the vertical one. In Ectodiis the horizon- 
tal and vertical limbs of the preopercu- 
lum are of equal length, while in Aspro- 
tilapia, Lestradea, Ophthalmochromis, 
and Ophthalmotilapia the horizontal 
limb of the preoperculum is the shorter 
one. The sensory canals and pores of the 
preoperculum are enlarged in Ophthal- 
mochromis and Ophthalmotilapia. 
Jaw apparatus (Fig. 4). As discussed 
above, the mandible of Ectodiis is spe- 
cialized in having an extensive shelflike 
adductor fossa in the anguloarticular and 
a laterally expanded ascending process of 
the dentary. The mandible of Lestradea, 
Cunningtonia, Ophthalmochromis, and 
Ophthalmotilapia exhibits a more gen- 
eralized configuration with very restrict- 
ed adductor fossae. The most specialized 
features are found in the mandible oi As- 
protilapia: the lower jaw is elongate and 
quite slender, with a drastic reduction in 
the depth of the unit; the large ascending 
processes of the dentary and articular are 
widely separated and form the bulk of the 
mandible. Morphologically, the premax- 
illae and maxillae in this lineage are very 
uniform, resembling those of Ectodus. 
But in Lestradea the body of the maxilla 
is stout, being only as long as the neck 
and associated condyles, and having a 
pronounced posteriorly directed post- 
maxillary process. In general, the ascend- 
ing processes are shorter than in Ecto- 
200 
Bulletin Museum of Comparative Zoology, Vol. 149, No. 3 
appm 
ppm 
mx 
Figure 4. Lateral aspects of the suspensorium, mandible, and upper jaw. A, Ectodus descampsi; B, Lestradea perspi- 
cax; C, Cunningtonia longiventralis; D, Asprotilapia leptura, in which only parts of the suspensorium are depicted, since 
the elements have been disarticulated; E, Ophthalmotilapia ventralis; F, Ophttialmotilapia boops. 
dus. However, both the premaxilla and diiced and shifted into a more forward 
maxilla in Asprotilapia (Fig. 4D) exhibit position. The shape of the shortened 
several unique specializations. In the maxilla deviates greatly from that of other 
premaxilla, the articular process is re- cichlids. The greatly enlarged cranial 
CiCHLiD Phylogeny* Liem 201 
^ pts bs 
sph^pa 
B 
pts 
soc 
sph ^.^-^ 
bs 
pf 
eo 
appm^ 
mx 
"^ms. 
'^ ' "^V;;;^rbp^P^'" 
soc 
d ^cf^/ 
ra 
mpt sy^ 
Figure 5. Lateral aspect of the skull. A, Ecfodus descampsi; B, Lestradea persp/cax; C, Cunningtonia longiventralis; 
D, Ophthalmotilapia ventralis; E, Ophthalmotilapia boops. 
202 Bulletin Museum of Comparative Zoology, Vol. 149, No. 3 
do ep 
do ep 
artTr7+— ^r' P°P 
lap lop 
do lo 
pop 
Figure 6. Lateral aspect of the cephalic musculature after removal of the lacrimal, circumorbitals, and eyes. A, Ectodus 
descampsi; B, Lestradea perspicax; C, Cunningtonia longiventralis; D, Ophthalmotilapia ventralis; E, Ophttialmotilapia 
boops; F, Asprotilapia leptura; G, deeper dissection of the adductor mandibulae complex after removal of part A. in 
Asprotilapia. 
CiCHLiD Phylogeny • Liem 
203 
condyle and premaxillary process consti- 
tute the bulk of the bone, with its dorsal 
extremity directed anteriorly as a flat- 
tened process. The angle between the 
body of the maxilla and the part bearing 
the cranial condyle and premaxillary pro- 
cess is more acute than that of other 
members of the lineage. 
Dentition. Much of cichlid classifica- 
tion and phylogeny has been based sole- 
ly on dental characters. In this lineage 
dental characters are of little value in es- 
tablishing phyletic relationships at the 
generic level, because the polarity of 
character transformation is not known, 
and intraspecific and ontogenetic plastic- 
ity further complicates the use of dental 
characters. No new information is added 
here to our already extensive knowledge 
on the teeth of members of this lineage 
(Poll, 1943; Poll and Matthes, 1962). In 
Ectodiis descampsi the teeth are conical 
and arranged in two to three rows in such 
a fashion that the outer rows on the lower 
jaw are directed outward. Lestradea per- 
spicax perspicax, a subspecies from the 
northern half of Lake Tanganyika, pos- 
sesses conical teeth arranged in three to 
four rows. The teeth of the outer row are 
much larger and are directed outward. In 
juveniles of L. perspicax stappersi the 
teeth are invariably tricuspid, while in 
the adult all teeth can become conical. 
Cunningtonia, Ophthalmochromis, and 
Ophthalmotilapia have teeth with long 
flexible stalks, giving them a mobile na- 
ture, which is regarded as an adaptation 
to raking and scraping algae off irregular 
rock surfaces. In Cunningtonia the tri- 
cuspid teeth are numerous, forming a 
broad band in each jaw. Characteristical- 
ly, the distal end of each tooth is bent 
backwards rather sharply. In Ophthal- 
motilapia most teeth are tricuspid 
throughout the life history of the fish, ex- 
cept for the conical ones toward the outer 
corners of the jaws. It is remarkable that 
the dental patterns in the subspecies of 
Lestradea closely parallel those in the 
subspecies of Ophthalmochromis. 
Ophthalmochromis ventralis ventralis is 
a conical-toothed form, geographically 
restricted to the northern half of Lake 
Tanganyika. In the southern subspecies, 
Ophthalmochromis ventralis heterodon- 
tus, the juveniles have tricuspid teeth, 
while later in development a mixed den- 
tition of tricuspid and conical teeth ap- 
pears. Asprotilapia has small teeth with 
very long slender stalks and expanded 
tricuspid crowns arranged in two rows. 
COMPARATIVE MYOLOGY 
The lateral head musculature in mem- 
bers of this lineage is relatively uniform 
(Figs. 6, 7, 8). The description given for 
Ectodus also applies to other members of 
the lineage except for Asprotilapia, 
which exhibits many unique specializa- 
tions in the lateral head musculature. In 
Asprotilapia (Fig. 6F,G) the elongate ad- 
ductor mandibulae part Ao is the domi- 
nant muscle occupying the greater part of 
the cheek region. From their origin on 
the preoperculum, the fibers run parallel 
to insert on the extensive adductor fossa 
of the mandible. Part A, of the adductor 
mandibulae complex in Asprotilapia is 
a small muscle originating from the pre- 
operculum and symplectic processes of 
the hyomandibula; its fibers insert on a 
tendon at a point about halfway between 
origin and insertion. Thus the tendon of 
part A] is exceptionally long; just beyond 
the ascending process of the articular it 
gives off a ventral branch which merges 
with the tendon of the intramandibular 
(A^v) part of the adductor mandibulae 
complex. The A, tendon inserts on the 
medial aspect of the maxilla in the area 
between the cranial condyle and premax- 
illary process. The adductor mandibulae 
complex of Lestradea, Cunningtonia, 
Ophthalmochromis, and Ophthalmoti- 
lapia deviates from that of Ectodus in the 
dominance of the A, part. Both in cross- 
sectional area and in volume, the A, is 
the largest component of the complex 
(Fig. 6). 
The configuration of the remaining lat- 
eral head muscles and the ventral head 
204 Bulletin Museum of Comparative Zoology, Vol. 149, No. 3 
bsr 
Figure 7. Ventral aspect of the ventral cephalic musculature with the hyohyoideus transversus partially or In B, entirely 
removed. A, Ectodus descampsi; B, Asprotilapia leptura; C, lateral view of the branchial musculature after removal of 
the gills and mucous membranes In Ophthalmotilapia nasutus. 
CiCHLiD Phylogeny • Liem 
205 
muscles in all members of this lineage 
conforms with that of Ectodus (Fig. 6). 
In general, the branchial musculature 
of members of this lineage resembles that 
of Ectodus (Figs. 7, 8). In Asprotilapia 
the transversus dorsalis anterior muscles 
have been reduced to only one head, run- 
ning between the 2nd pharyngobranchi- 
als (Fig. 8C:tda). Ophthalmotilapia ex- 
hibits two specializations in the dorsal 
branchial musculature: both the obliquus 
dorsalis and retractor dorsalis are greatly 
enlarged and are subdivided into two dis- 
tinct heads (Fig. 8D:od,rd). 
PHYLETIC ANALYSIS 
Although an in depth study on phyletic 
relationships is not yet available, it is 
generally accepted that the endemic la- 
custrine cichlids of Lake Tanganyika 
have been derived from several unrelat- 
ed fluviatile lineages. The fluviatile gen- 
era ''Tilapia,' Tylochromis, "Haplo- 
chromis," and Lamprologus are 
considered the primitive sister lineages 
of the many derived lineages of endemic 
cichlids in Lake Tanganyika (e.g., Regan, 
1920; Fryer and lies, 1972). Unfortu- 
nately, no attempts have been made to 
interrelate the different lineages witliin 
Lake Tanganyika on a sister group basis. 
Since the phyletic relationships of the la- 
custrine lineages are still poorly known, 
the determination of their sister group in- 
terrelationships with the more general- 
ized fluviatile lineages will be postponed 
until a much broader data base is avail- 
able. Without the information on the re- 
lationships of the lacustrine species and 
their respective fluviatile sister lineages, 
it is impossible to make precise outgroup 
comparisons. Despite these limitations, 
it is possible to construct a classification 
from which a theory of relationships is 
recoverable. Clearly its precision and ef- 
ficiency can be improved, but that must 
await a phyletic analysis of fluviatile taxa. 
In this phyletic analysis comparisons 
have been made between the lacustrine 
assemblage Asprotilapia, Ectodus, Les- 
tradea, Cunningtonia, OpJithalmo- 
chromis, and Ophthalmotilapia and the 
fluviatile taxa Astatotilapia burtoni and 
Sarotherodon nilotica. Tylochromis, 
Sarotherodon, Tilapia, and Lamprologus 
are specialized along very different lines 
(Liem, in prep.) and are not closely re- 
lated to the Ophthalmotilapia lineage. 
Although an outgroup comparison is ten- 
tative, I have considered the morphology 
of A. burtoni to be generalized (Liem, in 
prep.) and therefore representative of a 
plesiomorphous group with which the 
apomorphous Ophthalmotilapia assem- 
blage can be compared. In the succeed- 
ing phyletic analysis I have made the ba- 
sic assumption that the morphological 
condition of the various structures in As- 
tatotilapia burtoni and A. elegans rep- 
resents the primitive state. Any devia- 
tions from this basic morphological 
configuration are considered specializa- 
tions. Monophyletic lineages are then 
formulated on the basis of shared spe- 
cialized characters. 
The Ophthalmotilapia Assemblage 
AS A Monophyletic Lineage 
A comparison of the osteology and 
myology of all cichlid genera of Lake 
Tanganyika and the four fluviatile species 
Sarotherodon nilotica, Astatotilapia 
burtoni, Tylochromis microlepis, and 
Lamprologus congolensis has resulted in 
the identification of a suite of eight de- 
rived characters shared by Asprotilapia, 
Ectodus, Lestradea, Cunningtonia, 
Ophthalmochromis, and Ophthalmoti- 
lapia. This group of genera will be re- 
ferred to as OA (Ophthalmotilapia As- 
semblage) in the following discussion. 
The entopterygoid is separated from 
the palatine in the OA (Fig. 4:ent). In 
generalized cichlids the entopterygoid is 
attached to the posterior margin of the 
body of the palatine (Goedel, 1974; Van- 
dewalle, 1972; Liem and Osse, 1975; 
Barel et al., 1976) or the two elements 
abut against each other. A similar con- 
nection is also present in several special- 
206 Bulletin Museum of Comparative Zoology, Vol. 149, No. 3 
ebi.4 
Figure 8. Dorsal aspect of the branchial musculature. A, Ectodus descampsi, in which the dissection has been carried 
out in greater detail to show the precise insertions and origins of the muscles; B, Lestradea perspicax; C, Asprotilapia 
leptura; 0, Ophthalmotilapla boops. 
ized lineages of Lake Tanganyika, such as 
the herbivores (e.g., Simochromis and 
Petrochromis), piscivores (Liem, 1978), 
scale eaters (Liem and Stewart, 1976) and 
invertebrate pickers (Liem, 1979). Sepa- 
ration of the palatine and the entoptery- 
goid (Fig. 4:ent,p) is considered as a de- 
rived character state. This specialization 
also occurs in Xenotilapia (Liem and 
Osse, 1975), Aiilonocraniis, Callochro- 
mis, and Cardiopharynx indicating the 
possibility that these genera are related 
to the OA. However, on the basis of the 
present data it is impossible to ascertain 
that Xenotilapia, Aulonocranus, Calloch- 
romis, and Cardiopharynx are members 
of a sister lineage of the OA. 
The functional significance of the sep- 
aration of the entopterygoid from the pal- 
atine remains unclear, because no corre- 
lation can be found between this 
specialized feature and specializations in 
either the mobility and shape of the sus- 
pensorium and jaws, or the morphologi- 
cal characteristics of the adductor man- 
dibulae complex. 
A unique specialization of the OA can 
be found in the palatine bone (Fig. 
4E,F:p). The dorsal margin and the ver- 
tically directed posterior border of the 
palatine meet at a 90° angle. Because the 
palatine is expanded in the region of this 
90° angle, it has a characteristic shape 
when viewed laterally (Fig. 4:p). The 90° 
posterodorsal angle surmounting a pos- 
terodorsal expansion of the palatine is not 
found in any of the other Lake Tangan- 
yika cichlids and deviates from the con- 
dition in generalized cichlids (e.g., Asta- 
totilapia burtoni, Liem and Osse, 1975; 
A. elegans, Barel et al., 1976). This 
uniquely specialized shape of the pala- 
CiCHLiD Phylogeny • Liem 
207 
tine is found in all members of the OA, 
indicating that the group may represent 
a monophyletic lineage. 
The hyomandibula of cichlids exhibits 
remarkable diversity in shape and size. 
However, among the diverse forms one 
can recognize distinct themes, each of 
which may reflect a particular ancestry. 
The hyomandibula of Astatotilapia bur- 
toni (Liem and Osse, 1975) and A. ele- 
gans (Barel et al., 1976) is characteristi- 
cally stout, with an expanded flange 
associated with the relatively short sym- 
plectic process. In Tilapia and Saro- 
therodon (Vandewalle, 1972; Goedel, 
1974) the symplectic process is elongate 
and the hyomandibular flange below the 
anterior head is only moderately devel- 
oped. Both Lamprologus and Tylo- 
chromis possess a strongly modified hyo- 
mandibula. The slender hyomandibula of 
all members of the OA (Fig. 4:hm) resem- 
bles that of Tilapia, but it has a relatively 
longer symplectic process, and has lost 
its flange. However, a reduced flange is 
present in Asprotilapia. Because the spe- 
cialization of the hyomandibula in mem- 
bers of the OA has progressed further 
than in Tilapia, the feature is considered 
derived and indicative of the monophy- 
letic nature of the group. A similarly spe- 
cialized hyomandibula is found in Xen- 
otilapia. 
The anterior margin of the pterosphe- 
noid in members of the OA is peculiarly 
notched (Fig. 2:pts). A liplike process at 
the base of the notch serves as the origin 
of a strong ligament which attaches to the 
eye ball. Although the notched anterior 
margin of the pterosphenoid and the as- 
sociated ligament occurs in some other 
specialized cichlids, it is absent in the 
generalized forms. The presence of the 
pterosphenoid notch in all members of 
the OA is considered as supporting evi- 
dence for the hypothesis of monophyly of 
the OA. 
All members of the OA possess a very 
shallow suspensory apparatus at the level 
of the metapterygoid (Fig. 4). This spe- 
cialization is the result of a sharp de- 
crease in the vertical depth of the meta- 
pterygoid, which in all generalized 
cichlids has a much greater vertical 
depth. Actually among Lake Tanganyika 
cichlids this specialization and the pe- 
culiar position of the ectopterygoid is 
characteristic of the OA assemblage. 
Although the presence of a well-devel- 
oped auricular process (Fig. 5:op) on the 
operculum occurs in several specialized 
cichlid groups, the character is here in- 
cluded in the suite of derived characters, 
upon which the hypothesis of monophyly 
of the OA is based. 
Two myological specializations in the 
branchial musculature of all members of 
the OA offer further evidence for the 
probable monophyletic nature of the 
group. In sharp contrast to the condition 
in generalized cichlids, there is a clear 
reduction in the development of the 
transverse dorsalis muscle accompanied 
by a hypertrophy of the obliquus poste- 
rior muscle (Fig. 8:obp). Reduction of the 
transversus dorsalis and hypertrophy of 
the obliquus posterior have not been 
found in Astatotilapia elegans (Anker, 
1978) and other groups of specialized 
cichlids in Lake Tanganyika. In view of 
this admittedly tentative evidence, the 
reduction of the transversus dorsalis and 
hypertrophied obliquus posterior are 
considered derived characters support- 
ing the notion that the OA is actually 
monophyletic. 
The OA is viewed as a monophyletic 
lineage (Fig. 9: cladogram of synapomor- 
phies [1]-[301) because its members share 
the following suite of characters: 
(1) The entopterygoid is widely sepa- 
rated from the palatine. 
(2) The posterior and dorsal margins of 
the palatine form a 90° angle. 
(3) The slender hyomandibula has a 
long symplectic process and no or a 
very reduced hyomandibular flange. 
(4) The anterior margin of the ptero- 
sphenoid is notched. 
(5) The vertical depth of the metapter- 
ygoid is shallow. 
208 Bulletin Museum of Comparative Zoology, Vol. 149, No. 3 
(6) The operculum has a distinct aiiric- 
uhir process. 
(7) The transversus dorsaHs is reduced. 
(8) The obHquus posterior is enlarged. 
No other cichlid in Lake Tanganyika 
possesses this suite of derived characters, 
although none of the above mentioned 
characters, with the possible exception of 
(2), is autapomorphic. The sister group of 
the Ophthalmotilapia lineage is still un- 
known. Possibly, Xenotilapia, Callo- 
chromis, and Aulonocranus may repre- 
sent members of a sister group of the 
Ophthalmotilapia lineage since they do 
share two of the above mentioned de- 
rived characters (i.e., [1] and [3]). How- 
ever, the precise relationships of this lin- 
eage to others must await more data and 
further analysis now in progress. 
This phyletic hypothesis for the exis- 
tence of an Ophthalmotilapia lineage dif- 
fers from the previous hypotheses (Fryer 
and lies, 1972, and Regan, 1920) by the 
inclusion of Ectodus. In the previous 
schemes, Ectodus has been regarded as 
a derivative of a ''Haplochromis" or 
"Haplochromis-\ike" ancestor, while the 
other members of the Ophthalmotilapia 
lineage were seen as derivatives of "one 
or more unknown ancestors," which are 
not related to "Haplochromis J' Unfortu- 
nately the inferred relationships of the 
relevant genera in the previous hypoth- 
eses have been presented with virtually 
no documentation, and were not based 
on Hennigian methodology. 
Phyletic Relationships of 
Members of the 
Ophthalmotilapia Lineage 
The proposed phyletic relationships 
are depicted in the cladogram in Fig. 9. 
Two major lineages are recognized: one 
contains the monotypic genus Asproti- 
lapia, and the second lineage contains 
the five remaining genera. The following 
discussion deals first with the synapo- 
morphies for the entire complex, and 
then with those derived characters that 
distinguish subunits of decreasing levels 
of universality within the assemblage. 
Asprotilapia represents a very special- 
ized lineage, with six autapomorphic 
characters: 
(9) The elongate, slender mandible has 
an expanded adductor fossa (Fig. 
9:9) serving as the insertion site for 
the adductor mandibulae part A2 
(Fig. 6F,G). 
(10) The posterior head of the transver- 
sus dorsalis anterior is absent (Figs. 
9:10, 8C:tda). 
(11) The lateral ethmoids are greatly en- 
larged (Figs. IC, 3C:pf). 
(12) The interorbital width of the neu- 
rocranium is drastically reduced 
(Fig. IC). 
(13) The reduced articular process of the 
premaxilla is in a more forward po- 
sition (Fig. 4D:ap). 
(14) The greatly enlarged cranial con- 
dyle and the premaxillary process 
constitute the bulk of the maxilla 
(Fig. 4D:cc,pmp). 
The rare species Asprotilapia leptura 
represents a highly specialized lineage, 
with a very elongate body and a much 
attenuated caudal region. Because of the 
ventral mouth and the tricuspid teeth ar- 
ranged in two series on both jaws, As- 
protilapia is considered herbivorous, 
feeding primarily on epilithic algae. 
The remaining five genera are regard- 
ed as a monophyletic group on the basis 
of their sharing two derived characters: 
(15) Anteriorly the enlarged lachrimal is 
differentiated into a distinct process 
(Figs. 9:15, 5:1a). The blunt process 
is directed anteroventrally, except 
in Cunningtonia in which it is di- 
rected anterodorsally. 
(16) The adductor mandibulae part A, 
has become the dominant compo- 
nent of the adductor mandibulae 
complex (Fig. 6:ami). Its cross-sec- 
tional area surpasses that of the oth- 
er parts. The origin from the pre- 
operculum has expanded ventrally 
CiCHLiD Phylogeny • Liem 
209 
ASPROTILAPIA ECTODUS LESTRADEA OPHTHALMOTILAPIA CUNNINGTONIA 
VENTRALIS NASUTUS BOOPS 
Figure 9. Proposed cladogram depicting the phylogenetic relationships of the Ophthalmotilapia lineage on the basis 
of the following synapomorphies: (1) entopterygoid separated from palatine; (2) posterior and dorsal margins of palatine 
form a 90 angle; (3) slender hyomandibula with long symplectic process and reduced hyomandibular flange; (4) ante- 
rior margin of pterosphenoid notched; (5) vertical depth of metapterygoid shallow; (6) operculum with auricular 
process; (7) transversus dorsalis muscle reduced; (8) obliquus posterior muscle enlarged; (9) elongate, slender 
mandible with expanded adductor fossa; (10) transversus dorsalis anterior absent; (11) prefrontals greatly enlarged; 
(12) interorbital width greatly reduced; (13) reduced articular process of premaxilla in forward position; (14) cranial 
condyle and premaxillary process of maxilla greatly enlarged; (15) lacrimal enlarged with a distinct anterior process 
and elaborate sensory system; (16) adductor mandibulae part A, is dominant; (17) saccular bulla enlarged; (18) 
horizontal and vertical limbs of preoperculum of equal length; (19) elongate gut which is at least 2.5 times the 
fish's standard length; (20) edentulous anterior process of the lower pharyngeal jaw is only half as long as the 
toothed part; (21) stout body of maxilla with prominent postmaxillary process; (22) jaw teeth mobile with long stalks; 
(23) first pelvic fin ray is greatly elongate; (24) straight vertical limb of preoperculum forms a 90' angle with horizontal 
limb; (25) symplectic elongate; (26) a spinelike process at junction of dorsal and posterior margins of palatine; 
(27) long-stalked tricuspid jaw teeth with posteriorly recurved crowns; (28) distal end of elongate first ray uniquely 
bifid and widened into spatulae; (29) trend toward enlarged sensory canals and pores; (30) hypertrophied re- 
tractor dorsalis muscle subdivided into two distinct heads. 
at the expense of the adductor man- 
dibulae part Ag. 
Ectodiis inhabits shallow waters of 
sandy areas, feeding on a mixed diet of 
insect larvae, crustaceans, and filamen- 
tous algae. According to the present phy- 
logenetic hypothesis, Ectodus represents 
the most primitive of the Ophthcdmotila- 
pia lineage. Two autapomorphies distin- 
guish Ectodus from the other genera: 
(17) The saccular bulla is greatly en- 
larged (Figs. 2, 3). 
(18) The horizontal and vertical limbs of 
the preoperculum are of equal 
length (Figs. 4, 5:pop). 
The next monophyletic subunit is com- 
posed of Lestradea, Ophthalmotilapia, 
Ophthalmochromis, and Cunningtonia, 
which all share one notable feature: 
(19) The gut is elongate and is at least 
2.5 times the fish's standard length. 
Lestradea possesses a gut which is 2.5-4 
times the standard length. In Ophthal- 
motilapia and Ophthalmochromis the 
gut measures 3-3.5 times the standard 
length. The longest gastrointestinal tract 
is that of Cunningtonia, measuring 5-6 
times the fish's standard length. The rel- 
ative increase in the length of the diges- 
tive tract is correlated with an increased 
emphasis on a herbivorous diet. 
Within this subunit, Lestradea can be 
210 Bulletin Museum of Comparative Zoology, Vol. 149, No. 3 
distinguished by two autapomorphic 
characters: 
(20) The edentulous anterior process of 
the lower pharyngeal jaw is only 
half as long as the toothed part. 
(21) The body of the maxilla is stout and 
has a prominent postmaxillary pro- 
cess (Fig. 4). 
Cunningtonia, Ophthalmochromis , and 
Ophthalmotilapia form a distinct sub- 
unit sharing three specialized characters: 
(22) The jaw teeth have long stalks and 
are mobile. 
(23) The first pelvic fin ray is greatly 
elongate. 
(24) The posterior margin of the vertical 
limb of the preoperculum is straight 
and forms a 90° angle with that of 
the horizontal limb (Fig. 4). 
Within this monophyletic subunit, 
Cunningtonia possesses three autapo- 
morphic features: 
(25) The symplectic is very elongate, 
lengthening the suspensorium (Fig. 
4:sy). 
(26) At the 90° junction of the dorsal and 
posterior margins of the palatine is 
a spinelike process directed dorso- 
posteriorly (Fig. 4:p). 
(27) The long-stalked tricuspid jaw teeth 
have posteriorly recurved crowns 
(Fig. 6). 
Finally, the close relationship of 
Ophthalmochromis and Ophthalmotila- 
pia can be established on the basis of 
three derived characters: 
(28) The distal end of the very elongate 
first ray of each pelvic fin in the 
male is uniquely bifid and widened 
into spatulae. 
(29) All members of this subunit show a 
trend toward enlargement of the 
sensory canals and pores of the head 
(Figs. 1, 2, 5). 
(30) The hypertrophied retractor dorsalis 
is subdivided into two distinct heads 
(Fig. 8:rd). 
The genus Ophthalmochromis was es- 
tablished by Poll (1956) on the basis of 
O. ventralis, its type species possessing 
conical teeth in adults as well as juve- 
niles. Ophthalmotilapia hoops, on the 
other hand, has mainly tricuspid teeth, 
although conical teeth are present on the 
posterolateral corner of the jaws. The 
neurocranium of O. hoops has a shorter 
ethmovomerine region and a steeper eth- 
movomerine slope than that of Ophthal- 
mochromis ventralis. However, the con- 
dition with respect to the ethmovomerine 
region in the skull of Ophthalmochromis 
nasutus is intermediate between that of 
hoops and ventralis. The validity of 
Ophthalmochromis and Ophthalmotila- 
pia as distinct genera is questionable. 
Originally the distinction between 
Ophthalmochromis and Ophthalmotila- 
pia was based on morphological gaps in 
the general and skull morphology. With 
the discovery of Ophthalmochromis na- 
sutus, the few morphological gaps of 
characters in the skulls of ventralis and 
hoops are bridged. Ophthalmochromis 
nasutus has an ethmovomerine slope in- 
termediate between those of ventralis 
and hoops. The subtle differences in the 
decurvature of the skull anteriorly be- 
tween Ophthahnochromis and Ophthal- 
motilapia are well within the range 
found intragenerically in Perissodus 
(Liem and Stewart, 1976). In the related 
genus Lestradea, the contrast between 
tricuspid and conical teeth has been in- 
terpreted to indicate a difference at the 
subspecies level for, respectively, L. per- 
spicax stappersi and L. perspicax perspi- 
cax. In Lestradea tooth shape changes 
ontogenetically from tricuspid to bicus- 
pid and conical. In ventralis, nasutus, 
and hoops geographical variation has 
been demonstrated very convincingly 
(Poll and Matthes, 1962). Conical teeth 
do occur in all species, even though in 
hoops the tricuspid form is dominant. In 
view of the fact that tooth form in some 
members of this lineage can change dras- 
tically from tricuspid to conical during 
ontogeny, and that conical teeth actually 
CiCHLiD Phylogeny • Liem 211 
occur in all forms varying only in relative 
abundance, the presumed "morphologi- 
cal gap" between ventralis and nasutus 
on the one hand, and hoops on the other 
hand, is nonexistent and does not justify 
the recognition of two genera. 
^ More importantly, the phylogenetic re- 
lationships as depicted in Fig. 9 indicate 
that ventralis, nasutus, and hoops share 
a recent common ancestor not shared by 
any of the other taxa. I propose, therefore, 
that Ophthalmotilapia and Ophthalmo- 
chromis be considered synonyms. The 
name Ophthalmotilapia established by 
Boulenger in 1901 has priority over 
Ophthalmochromis (Poll, 1956). 
"Adaptive Radiation" of the 
Ophthalmotilapia Lineage 
Once the phyletic nature and relation- 
ships of the Ophthalmotilapia lineage 
have been established, a more meaning- 
ful statement can be made concerning 
their adaptive radiation. 
Unlike most cichlid lineages, the radia- 
tion in the Ophthalmotilapia lineage es- 
pecially has involved behavioral patterns 
in courtship and specific recognition sig- 
nals, although the feeding apparatus does 
exhibit some morphological diversity. All 
are oral brooders, but in Cunningtonia 
and Ophthalmotilapia the pelvic fins of 
the males are drawn out into long slender 
filaments whose tips reach posteriorly to 
the margin of the anal fin and terminate 
in brightly colored spots which function 
not only for species recognition, but 
probably also as egg dummies (Fryer and 
lies, 1972: 110, 121). The strikingly 
colored tips of the elongated pelvic fins 
play an important role in specific, and, 
thus inevitably, in sex recognition in the 
complex communities where Cunning- 
tonia and Ophthalmotilapia occur. Both 
Cunningtonia and Ophthalmotilapia 
produce only a few eggs, measuring 3.5- 
4 mm in diameter. Egg collecting pre- 
cedes fertilization. Ectodus, the most 
primitive member of the lineage, and 
Lestradea produce larger clutches (20- 
30) of smaller eggs (2 mm) and lack the 
specialized brilliantly colored tips on the 
elongate pelvic fins. The males of Les- 
tradea and Ectodus possess different 
specific recognition signals, and their 
courtship behaviors differ from those of 
Cunningtonia and Ophthalmochromis. 
In Lestradea and Ectodus egg laying, 
fertilization, and collection by the female 
take place rapidly in that sequence. The 
courship behavior of Asprotilapia is un- 
known. 
Members of the Ophthalmotilapia lin- 
eage occupy three types of habitat. Gen- 
erally, Asprotilapia, Cunningtonia, and 
Ophthalmotilapia inhabit the offshore 
margins of the shallow, rocky littoral ad- 
jacent to the sandy bottom. O. ventralis 
often penetrates to greater depths of up 
to 5 m. Lestradea inhabits shallow areas 
with both sandy and rocky bottoms. L. 
perspicax stappersi is common at greater 
depths down to 50 m. The littoral habitat 
of Ectodus is much narrower, being con- 
fined to the shallow waters with sandy 
bottoms. Except for Ectodus, all mem- 
bers of the Ophthalmotilapia lineage are 
not restricted to a particular habitat but 
move freely between habitats with hard 
and soft bottoms. The absence of strong 
habitat restriction means the crossing of 
"alien" habitats whether or not condi- 
tions are adverse. As a result, a spectrum 
of food resources is exploited. Judging 
from the anatomy, stomach contents, and 
behavior in the laboratory, members of 
the Ophthalmotilapia lineage possess an 
extensive feeding repertoire. Thus the 
feeding pattern exhibited by the 
Ophthalmotilapia lineage resembles that 
of other cichlids in which increased func- 
tional and morphological differences in 
the trophic apparatus (dentition, jaw 
structure, skull morphology, and pharyn- 
geal myology) do not necessarily lead to 
a greater separation on the food axis 
(Liem, 1980). 
The comparative anatomical and phy- 
logenetic data presented in this study 
reinforces the paradox (Liem, 1980; 
Greenwood, in prep.) that the morpho- 
212 Bulletin Museum of Comparative Zoology, Vol. 149, No. 3 
logically and phylogenetically most spe- 
cialized cichlid taxa are not only remark- 
able specialists but also jacks-of-all-trades. 
How the morphological radiation of the 
feeding apparatus has evolved remains a 
major problem in understanding the 
causal factors underlying the spectacular 
diversifications in the cichlid trophic 
structures. If specialists are simulta- 
neously jacks-of-all-trades, they defy the 
commonly accepted ecological notion 
that broadening the range of usable re- 
sources prevents species from specializ- 
ing on individual types. So far, most stud- 
ies have attempted to correlate the 
morphological diversity in the feeding 
apparatus of cichlids with adaptation and 
therefore fitness. However, Carson (1970) 
and Fryer (1977) have suggested that spe- 
ciation and adaptation are not necessarily 
synchronous processes. Carson has of- 
fered evidence that in Hawaiian dro- 
sophilids speciation may have preceded 
adaptation. 
Although there is no doubt that the 
Ophthabnotilapia lineage has under- 
gone extensive morphological radiation 
in both skull structure and dentition, the 
data on morphology, function, trophic 
ecology, and behavior of this and other 
cichlid lineages (Liem, 1980) have failed 
to establish unequivocally that the mor- 
phological radiation is also adaptive. 
ACKNOWLEDGMENTS 
I am greatly indebted to Dr. P. H. 
Greenwood of the British Museum of 
Natural History for making available lab- 
oratory facilities and collections and for 
his thorough and critical review resulting 
in a much improved manuscript. Karsten 
Hartel of the Museum of Comparative 
Zoology, and Gordon Howes and James 
Chambers of the British Museum have 
offered their skills in solving numerous 
problems during the course of this study. 
Sara Fink has produced several of the 
drawings and Christine Fox has typed 
and edited the manuscript and legends. 
William Fink and George V. Lauder, Jr. 
have made important contributions and 
suggestions throughout the progress of 
this study. To all of the above individuals 
I am much indebted. This research was 
supported by National Science Founda- 
tion Grants DEB 79-00955 and DEB 76- 
04386. 
ABBREVIATIONS 
a: anguloarticular 
aap: adductor arcus palatini 
ad: adductor branchialis 
ad,: fifth adductor 
af: adductor fossa 
am,: adductor mandibulae pars A, 
amj: adductor mandibulae pars Aj 
amg: adductor mandibulae pars A3 
ao: adductor operculi 
ap: articular process 
apa: ascending process of articular 
apd: ascending process of dentary (coronoid) 
appm: ascending process of premaxilla 
apu: apophysis of upper pharyngeal jaw 
bh: basihyal 
boc: basioccipital 
bs: basisphenoid 
bsr: branchiostegal ray 
ca: rostral cartilage 
car: rostral cartilage 
cbj: first ceratobranchial 
cb,: fifth ceratobranchial (lower pharyngeal jaw) 
cl: cleithnim 
con: cranial condyle 
d: dentary 
do: dilatator operculi 
e: ethmoid 
eb: epibranchial 
eb,: first epibranchial 
eb3_4: third and fourth epibranchial 
ect: ectopterygoid 
ent: entopterygoid 
eo: epiotic 
eoc: exoccipital 
ep: epaxial muscles 
f: frontal 
gha: geniohyoideus anterior 
ghp: geniohyoideus posterior 
hh: hyohyoideus 
hhi: hyohyoideus inferior 
hhs: hyohyoideus superior 
hht: hyohyoideus transversus 
hm: hyomandibula 
by: hyoid 
ic: intercalar 
ini: interniandibularis 
iop: interoperculum 
la: lacrimal 
1,: palatomaxillary ligament 
CiCHLiD Phylogeny • Ltem 213 
I2: palatopalatine ligament BoULENGER, G. A. 1900. Materiaux pour la faune 
li: craniopalatine ligament du Congo. Poi.sson.s nouveaux du Congo. Six- 
I4: ethmopalatine ligament ieme Partie: Mormyres, Characins, Cyprins, 
lap: levator arcus palatini Silures, Acanthopterygiens, Dipneu.stes. Ann. 
164: fourth levator externus Mus. Congo, Zool. 129-164. 
li,_2: first and second levator internus . 1901. Diagnoses of new fishes discovered 
lim: interoperculomandibular ligament by Mr. J. E. S. Moore in Lakes Tanganyika and 
lo: levator operculi Kivu. II. Ann. Nat. Hist. 7: 1-6. 
Ip: levator posterior . 1906. Fourth contribution to the ichthyol- 
md: mandible ogy of Lake Tanganyika. Report on the collec- 
mml: medial mandibular ligament tion of fishes made by Dr. W. A. Cunnington 
mpt: metapterygoid during the third Tanganyika Expedition 1904- 
mx: maxilla 1905. Trans. Zool. Soc. London 17: 537-576. 
n: nasal Carson, H. L. 1970. Chromosome traces of the 
obp: obliquus posterior origin of species. Science, N.Y. 168: 1414- 
od: obliquus dorsalis 1418. 
op: operculum DuLLEMEljER, P., AND C. D. N. Barel. 1977. 
p: palatine Functional morphology and evolution. Pages 
pa: parietal 83-117 in Hecht, Goody, and Hecht, eds. Major 
pbj: second pharyngobranchial patterns in vertebrate evolution, 
pb.-,: third pharyngobranchial FRYER, G. 1977. Evolution of species flocks of 
pbj: fourth pharyngobranchial cichlid fishes in African lakes. Z. Zool. Syst. 
pee: pharyngocleithralis externus Evolut.-forsch. 15: 141-165. 
pci: pharyngocleithralis internus FRYER, G., AND T. D. Iles. 1972. The cichlid fish- 
pf: lateral ethmoid complex es of the great lakes of Africa: Their biology 
ph: pharyngohyoideus and evolution. Oliver and Boyd, Edinburgh, 
pm: premaxilla GOEDEL, W. 1974. Beitrage zur vergleichenden 
pop: preoperculum und funktionellen Anatomie des Kopfes von 
pp: postmaxillary process of maxilla Tilapia (Cichlidae, Teleostei). Teil 1. Zool. Jb. 
ppm: protractor pectoralis (Anat.) 92: 220-274. 
ps: parasphenoid GREENWOOD, P. H. 1974. The cichlid fishes of 
pts: pterosphenoid Lake Victoria, East Africa: The biology and 
pv: vomer evolution of a species flock. Bull. Br. Mus. Nat. 
q: quadrate Hist. (Zool.) Suppl. 6: 1-134. 
ra: retroarticular . 1979. Towards a phyletic classification of 
rd: retractor dorsalis the "genus" Haplochromis (Pisces, Cichlidae) 
rf: rostral fossa and related taxa. Bull. Br. Mus. Nat. Hist, 
sh: sternohyoideus (Zool.) 35: 265-322. 
so: circumorbital LlEM, K. F. 1974. Evolutionary strategies and mor- 
soc: supraoccipital phological innovations: Cichlid pharyngeal 
sop: suboperculum jaws. Syst. Zool. 22: 425-441. 
sph: sphenotic . 1978. Modulatory multiplicity in the func- 
st: pterotic (supratemporal) tional repertoire of the feeding mechanism in 
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