Taxonomy and biogeography of African fruit bats (Mammalia, Megachiroptera). 5. The genera Ussonycteris Andersen, 1912, Myonycteris Matschie, 1899 and Megaloglossus Pagenstecher, 1885; general remarks and conclusions; annex: key to all species

80 Pages·1997·7.2 MB·English

by  Bergmans, Wim

Beaufortia
INSTITUTE FORSYSTEMATICSAND POPULATIONBIOLOGY
(ZOOLOGICAL MUSEUM) UNIVERSITYOFAMSTERDAM
Vol. 47, no. 2 June 20, 1997
TaxonomyandbiogeographyofAfrican fruit bats
(Mammalia, Megachiroptera).
5. ThegeneraUssonycteris Andersen, 1912, Myonycteris Matschie, 1899and
MegaloglossusPagenstecher, 1885;
generalremarksand conclusions; annex:key to allspecies
Wim Bergmans
Institute,forSystematicsandPopulation Biology (£'oologisch Museum), UniversityofAmsterdam, P. 0.Box 94766, 1090GT
Amsterdam,theNetherlands
Abstract
This is the lastpartin aseriescomprising all Megachiroptera known frommainland Africa and its islands. The conceptof
the genus LissonycterisAndersen, 1912 isreviewed and adapted.For the firsttime,its differential characters vis-à-visthe gen-
eraRousettus Gray, 1821,and Myonycteris Matschie, 1899 asdescribed inthe literature have beencheckedagainst material
ofallthe species involved. Asaconsequence, anumber ofthesecharacters areconsidered ofnotaxonomicvalue and have
notbeenretained,while somenewdifferential characters aredescribed. Lissonycteris and Myonycterisareconsidered different
from Rousettus ongenericlevel, while Lissonycteris and Myonycterisaremore closelyrelated toone anotherthan each ofthese
to Rousettus. New observations onall African and extralimital species ofRousettus arereported and the retention ofBoneia
Jentink, 1879 asasubgenusby Corbet etal. (1991, 1992)isrejected. Lissonycteris is considered amonotypicgenus, with as
single species thepolytypic L. angolensis(Bocage, 1898). The subspecies angolensis,smithii(O. Thomas, 1908) and ruwenzorii
(Eisentraut, 1965) arerecognized, and two new subspecies, petraea and goliath,are described. Myonycteris consists ofthree
species, torquata(Dobson, 1878),brachycephala (Bocage, 1889)and relicta Bergmans, 1980.Theirpresenttaxonomy iscon-
form earlier reports (Bergmans, 1976, 1980a).M. torquata is considered amonotypical species. M. relicta is reported from
Zimbabwefor the first time,extending its known distribution 1400 km southwards. Following Kirsch et al. (1995)and
Springeretal. (1995),the subfamily Macroglossinae isconsidered asynonym ofthe subfamilyPteropodinae.The taxonomy
and distributionofMegaloglossus woermanniPagenstecher, 1885 arereviewed. In afinal section, generalremarks and conclu-
sions are presented onthe supraspecific taxonomy ofthe Megachiroptera and aclassification isproposedwhich includes
the raise tosubfamily rank ofthe Rousettinae and Epomophorinaeand therecognition ofthenew tribes Scotonycterini
andPlerotini; somerecentpublications bearing onAfrican species taxonomyarereviewed;and anappraisal is madeofthe
distributionpatternsfound throughout this series. A vicariance modelis proposedtoexplainthe occurrence in Asia and
Africa ofboth Pteropus Brisson, 1762 and Rousettus Gray, 1821.For woodland species, theregions SE Tchad/E Central
AfricanRepublic/W Sudan;N halfofTanzania;and EAngola/adjoiningZaïrehave been identifiedashaving(had)abar-
rier effect ondispersal. For forestspecies, important dividesappear to be in the regions Volta River/Dahomey Gap; SE
Nigeria; Cand S Gabon;C Zaïre,from N toS; theWestern Rift system; severalbarriers in EAfrica.Finally, anillustrated
key to allAfrican Megachiropteraisgiven,primarily basedonexternallyvisible charactersand designedforuseinthefield.
11
R.
INTRODUCTION celebensis). In his Addendaand Corrigenda,
Andersen(1912: 814-815) added, on the basis of
For a general introduction to the series ofwhich the species Rousettus smithi O. Thomas, 1908not
this paper forms the fifth part, the reader is previously considered by himand also represent-
referred to thefirst part(Bergmans, 1988), which ing Lissonycteris, that Lissonycteris would probably
also contains a section Materials and Methods, be considered a genus, distinct from Rousettus, by
including the abbreviations used. (Most often future systematists. He added some diagnostic
used are fal = forearm length, and gsl = greatest characters: the flattening of the posterior brain-
skull length.) The gazetteer of African fruit bat case (which with the only slight deflection gives
localities announcedin the first partof this series the skull in profile a rather striking resemblance
has been completed but, for financial reasons, to thatofEpomophorus Bennett, 1836); the lesser
will be produced separately, and is availableon height ofthe rostrum; the thinascending branch-
request. es of the premaxillae; the more inflated frontal
sinuses; the relatively longer postdental palate;
the different morphology ofthe cheek-teeth, with
TAXONOMIC SECTION their outer and inner ridges much more cusp-
like, shorter antero-posteriorly, and higher verti-
cally, those in P separated (against fused in Rou-
Lissonycteris Andersen, 1912 4
settus) and those ofMb M2 and M3 even slightly
diverging above; the reduction of M1 (smaller
Lissonycteris Andersen, 1912:23, 814 (as subgenus ofRousettus
than P4 larger than this in Rousettus); the short-
Gray, 1821;typespecies: Cynonycteris angolensis Bocage, ,
1898); Leche, 1921: 41; Benedict, 1957:292, 300; ness of the tibia; and the conspicuously greater
Koopnian, 1975: 361, 1994: 20. lengths ofthefingers.
Lissonycteris (as agenus);Schwarz, 1920;Novick, 1958a: 445- Schwarz (1920) listed Lissonycteris as a genus,
457; Lawrence etal., 1963;Rosevear, 1965: 79, 84; withoutfurthercomment.
Kingdon, 1974: 124; Bergmans, 1980: 179; Haiduk et Leche (1921) pointed out thatAndersen's ana-
al. 1980: 187, 1981, 1984;Kirsch etal, 1995;Springer lysis of the exceptional position vis-a-vis typical
,
etal., 1995. Rousettuswouldjustify its raiseto generic rank.
Benedict (1957) foundthat the form of the
Andersen (1907b) included Cynonycteris angolensis hairscales in Lissonycteris is more similar to thatin
Bocage, 1898inRousettusGray, 1821.A fewyears the Epomophorus section (sensu Andersen, 1912)
later, he proposed the subgenus Lissonycteris for than that in the Rousettus section. She also ob-
whathecalled the "most aberrantspecies ofRou- served that while typical Rousettus has conspicu-
settus” (Andersen, 1912: 23, 53). He compared it ous overhair, Lissonycteris lacks overhair entirely
with the following species of typical Rousettus: (and Stenonycteris has sparse overhair).
egyptiacus, amplexicaudatus, celebensis, and leschenaultii Novick (1958a) treated Lissonycteris as a genus,
(all but celebensisstill undermore than one species referring to Novick and Lawrence, 1958, apaper
name). As diagnostic characters ofLissonycteris which appeared, however, only in 1963andwith
Andersenmentionedits only slight brain-case de- Lawrenceas the first author. Novick (1958a) add-
flection (against moderate inRousettussensu stric- ed to the arguments the fact that Lissonycteris ori-
to); the ossification ofthe premaxiOaries (which ents visually and lacks the faculty ofacoustic ori-
he found only exceptionally in old specimens of entation foundin at least three species of typical
one typical Rousettus species); the peculiar, sub- Rousettus, i.e. egyptiacus, leschenaultii (as seminudus),
quadrate outlines of the cheek-teeth (against and amplexicaudatus.
oblong in Rousettus); the extreme reduction of P, Lawrence et al. (1963) re-examined the gener-
(against a less strong reduction in Rousettus); the ic status andrelationships oftypical Rousettus and
attachment of the wing to the second toe (to the Lissonycteris, prompted by differences in non-flight
first toe in Rousettus); the distinct 'antitragal' lobe locomotion and orientation observed between
(small and rounded in Rousettus); the long and live specimens ofboth. Theirobservations in-
silky fur (against short in Rousettus - except clude the following: Rousettus inhabits dimly lit
12
caves with large entrances and shelteredretreats, orbits are larger, the nostrils are more promi-
where they hang in large clusters along the walls nent, the calcaris weaker, thewings are relative-
or ceiling, by their hind feet andwith theirbacks ly larger (metacarpal and first phalanx offifth
to the wall, the wings foldedat theirsides. There digit conspicuously longer than forearmin Lisso-
is no general observationon cave type or colony nycteris, aboutequal to itinMyonycteris, andmuch
size ofLissonycteris in thispaper butone remark is shorter in Rousettus); the attachment ofthe wing
of importance. While Novick (1958a: 445) sug- near the middle of the first phalanx of the sec-
gested that, like Rousettus, Lissonycteris was cap- ond toe (in Myonycteris: ditto; in Rousettus usually
tured "from large cave-dwelling colonies", between metatarsals one and two, sometimes
Lawrenceetal. mentionedthatonly asingle wild near the basis of the first phalanges, often well
colony ofabout 20 Lissonycteris was observed. proximal to this); the odontoid papillae border-
Lissonycteris always roosts hanging free from the ing the lips: rather high and pointed, forming a
ceiling ofthe cave. Rousettususes allfour limbsin single row extending from the angle of the
entering and leaving crevices: its feet and its mouthforward about to the canines (in Myonyc-
wrists inwalking, and its thumbsin climbing ver- teris: ditto, with a poorly defined second row on
tically or even upside downalong irregular sur- the upper lip; in Rousettus: a reduced single row
faces or branches. To this purpose, it is able to of small papillae); the palatal ridge pattern, with
fold its wings considerably. Lissonycteris never uses nearly straight ridges 1-3, a dividedridge 4, and
its wings for locomotion other than flight. It somewhat converging ridges 4-7 in Lissonycteris
would therefore also never enter crevices to and Myonycteris (more bowedforward, usually
roost. It is not able to fold its wings as tight as undivided, and more parallel, respectively, in
Rousettus. It does not land on horizontal surfaces Rousettus); furthermore, Lissonycteris and Myonyc-
and, when forcedto, shows awkwardand incom- teris haveashorter, less robusttail, longer, denser
petent movements only, whileatleast incaptivity fur on the notopatagium and the proximal dor-
Rousettusfrequently crawls. Rousettus occasionally sal surface of the tibia, a smaller foot with a
uses its wrists and thumbs to readjust morsels of webbed basal quarter to third ofthe first pha-
fruit in its mouth and only on one occasion was langes, slenderer claws, and an extensive patch
seen using its hindfootclaws to manipulate food of glandular fur on the throat ofadult males.
in its mouth. Lissonycteris regularly uses its hind Lawrence etal. (1963) also mentioneda number
feetfor handling its food, but rarely its wrists or of cranial and dental characters distinguishing
thumbs; it grasps fruit with its teeth and then Lissonycteris and Myonycteris from Rousettus: a rela-
brings a foot downto its mouth to hold the bulk tively long anterior skull part(from thetips ofthe
withwidely spread toes and, after having bitten premaxillaries to behind the postorbital process-
off a morsel, holds the remainder against its es) as compared with both brain-case length
chest or abdomen, frequently wholly or partly (from behind the postorbital processes) and its
covered by its wings. Rousettus never seems to bulk; aslenderrostrum, withposteriorly depress-
store fruit in its cheeks or to fly with any in its ed nasals; greatly developed lateral frontalsinus-
mouth, but generally stays to eat at the food es; raised posterior orbital margins; a concave
source. It seems to swallow fruit fibers together interorbital region; an elongated and flattened
with thejuice. Lissonycteris tends to hold food in posterior brain-case; a largerorbit, witha sharp-
its cheeks and carry food to its roost, and after er edged antero-ventral border, plate-like where
having expressed and swallowed thejuice will it is pierced by the infraorbital canal; dilferent
drop thebolus offiber. shape and spacing ofthe teeth; a differentocclu-
To these differencesin ecology, roosting pos- sionpattern.
ture andbehaviour, limbuse, and feeding behav- Kingdon (1974) referred to Lawrence et al.
iour Lawrence et al. (1963) added the following (1963) and suggested that the separation be-
morphological differences (in part quoted from tween Lissonycteris and Rousettus (and Stenonycteris,
the diagnosis ofMyonycteris in Andersen, 1912): which he also regarded as a genus) may bemore
In Lissonycteris and Myonycteris, compared with ancientthan the radiationofotherfruit bat gen-
Rousettus, the facial axis is less deflected, the era. He added that all threeoccupy distinct eco-
13
logical niches, which he considered an important They did find differences, however, in the G-
criterion for the recognition of genera. In King- bands. L. angolensis shows a polymorphism in pair
don'svision, Lissonycteris wouldrepresent aprimi- 1 which is not sharedby R. egyptiacus. The latter
tive type of fruit bat, roosting very much as species has two pericentric inversions in pair 1
ancestral forms, in hollowtrees andwell-lit caves. which are not found in L. angolensis. The species
(On one occasion, Kingdon captured a specimen were both compared with Myonycteris torquata
roosting in dense undergrowth in montane for- (Dobson, 1878), which differs from L. angolensis
est.) The ancestors of modern Rousettus (and only in having a differentpolymorphism in pair
Stenonycteris) developed a way to echolocate and 1. In their schematic presentation ofchromoso-
could thenexploit the darkerparts ofcaves. They mal evolution Haiduk et al. (1981) grouped
could afford to remain conservative because no Lissonycteris angolensis with Myonycteris torquata,
other fruit bat followed them there. (This is true while Rousettus egyptiacus is placed at some dis-
for present-day Africa and Madagascar, but not tance. But they emphasized that this arrange-
for large parts of SoutheastAsia, whereEonycteris ment does not imply evolutionary relationships
Dobson, 1873 forms large dark-cave colonies - and merely represents a possible sequence of
unless this isalso arousettinebat. See thegeneral chromosomalevents.
remarks and conclusions. W.B.) Apart from the
difference in roosting sites between Lissonycteris From the above as well as from the synonymies
and the others, Kingdon did not elaborate the underthespecies andsubspecies it is clear thatat
ecological niche differences. present two opinions on the systematic position
Koopman (1975), following Rosevear (1965) of Lissonycteris are diagonally opposed: its place-
in regarding Lissonycteris as monotypic, put for- ment as asubgenus in the genusRousettus and its
wardthat manyofthecranial and dentalcharac- placement as a genuson its own. However, many
ters mentioned by Lawrence el al. (1963) by authors appear to base their opinion solely on
which Lissonycteris (and Myonycteris) differ from that ofothers and seem not to be aware of views
Rousettus do not holdwhenall Rousettusspecies are opposing theirs. For this reason, the comments
examined. He regarded only thefollowing as reli- below are very detailed. For these comments,
able: the dish-faced appearanceof the interor- ZMA material ofLissonycteris has been compared
bital region; the larger orbit; the orbital rim; and with material ofMyonycteris torquata and M. relicta
the relatively large lateral frontal sinuses. All and all nine currently recognized Rousettus spe-
these characters he supposed to be related to the cies, all in the same collection except M. relicta
larger size of the eye, which in turn may be relat- (which is no. 62472 in the Natural History Mu-
ed to the absence ofecholocation (Koopman, seum inBulawayo, Zimbabwe- NHMBZ). Mate-
1975). Koopman thereforeretained Lissonycteris as rial ofAfrican species is listed in the species
a subgenus ofRousettus, also in his recent survey accounts in the present series (Bergmans, 1994;
ofbat systematics (Koopman, 1994). this paper). Extralimital material ofRousettus is
Bergmans (1980) mentionedthe narrowing of listed in Rookmaakeret al. (1981) and Bergmans
the anterior palate, resulting in the tooth-rows et al. (1988) except: R. leschenaultii from Koira,
being curved inward, and the relative heaviness Orissa, India (ZMA 20.492/97); Khab No Koi
of P4 as characters ofboth Lissonycteris and Myo- and TabKwang, both inThailand(ZMA 21.669
nycteris and not foundinRousettus. /70); and R. spinalatus from Batu Timbang,
Haiduketal.(1980) studied the standardkary- Sabah, Malaysia (ZMA 23.132/33). Of Myonyc-
otype ofLissonycteris angolensis and founda diploid teris brachycephala (Bocage, 1889), detailed skull
number (2n) of 36 and a fundamental number drawings were available (Andersen, 1912; this
(FN) of66. They expressed some doubt whether paper, figs. 7a-d), and ofM. relicta Bergmans,
Dulic etal. (1973), who published a2n of36 and 1980, slides ofskull and skin oftheholotype spec-
an FN of68 for Rousettus egyptiacus, would not be imen and a newly discovered specimen from
mistaken. In 1981, Haiduk et al. examined the Zimbabwe(this paper). The following specimens
latter species themselves, andfoundthe sameval- have been used to calculate relative measure-
ues for 2n and FN as in Lissonycteris angolensis. ments:Lissonycteris angolensis, d1from Pointe Noire,
14
Congo (ZMA 15.537);Myonycteris torquata, Cf from The "flattening" of theposterior brain-case in
Pointe Noire (ZMA 15.423); M. relicta, 9 from Lissonycteris is, in fact, the dorsal component of a
Haroni-Lusitu confluence, Zimbab-we(NHMBZ constriction of the skull somewhat behind the
62472); Rousettus egyptiacus, c? from Cairo, Egypt posterior insertion of the zygomatic arch. This
(ZMA 22.205); R. amplexicaudatus, c? from constriction isalso present in Myonycteris and, to a
Ambon, Indonesia(ZMA 21.442); R. bidens, cf variable extent, Rousettus. In Rousettus, the actual
from Imandi market, Indonesia (ZMA 22.759); constriction is generally not as distinct, while in
R. celebensis, cf from Kuala Navusu, Indonesia most species the deflection of the brain-case
(ZMA 18.571); R. lanosus, Cf from Menengai, tends to mask it still more. Nevertheless, the pos-
Kenya (ZMA 20.428); R. leschenaultii, 9 from terior brain-case in Lissonycteris and Myonycteris is
Koira, India (ZMA 20.497) and aC? from Bogor, relatively low.This can beassessed by comparing
Indonesia(ZMA 16.656); R. madagascariensis, 9 the relative occipital heights (the distance, in the
from Bevato ofNamoroka, Madagascar (ZMA median plane, between the occipital ridge and
19.312); R. obliviosus, imm. 9 from Anjouan, Co- the ventral margin ofthe foramenmagnum- or
mores (ZMA 20.903); R. spinalatus, d" from Batu the line connecting the most ventral points ofthe
Timbang, Malaysia (ZMA 23.132). occipital condyles, related to gsl, or brain-case
length). Only inRousettus bidens the occipital
height is aslow as in thetwo other genera.
Skull The elongation ofthe brain-case was mea-
sured by Lawrenceetal. (1963) by comparing the
Andersen (1912) measuredbrain-case deflection distance from the bottom of the occipital con-
by projecting the upperalveolar line backward dyles to the top of theoccipital crestwith thedis-
and noting wherethe projection cuts the occipital tance from the postglenoid process to the backof
region. In allRousettus species, the alveolar line is the condyle. In Lissonycteris and Myonycteris they
relatively straight. In Lissonycteris and Myonycterisi it found that thefirst distancewas smaller than the
is not, and its projection is a dubiousaffair. The second, in Rousettus it was larger than this or
present author has compared deflection by plac- equal to it. As hasjust been pointed out, the rela-
ing the skull, with the mandible in situ, on an tive occipital height in the first two genera is
even surface, resting it on the mandibularramus lowerthanin allRousettusspecies but bidens, and it
excluding the projecting angular process (this has doesnot seem tooffer thebest means to establish
to sink into the surface); the relative distance brain-case elongation. Moreover, it proved im-
between the occipital condylae and the surface is possible to reproduce all of the findings ofLaw-
a measure for the deflection. (A still better rence etal. (1963). Thefirst distancewas foundto
methodwouldbe to measure the angle between be smaller thanthe secondin Lissonycteris (with a
facial axis and basicranial axis on lateral view differenceof2.4), Myonycteris torquata (1.8), and all
photographs.) It appeared that there is little Rousettus species (2.8 in bidens and 0.2-1.4 in the
brain-case deflection in Lissonycteris, Myonycteris, others) exceptobliviosus and some leschenaultiishort-
Rousettus egyptiacus and R. leschenaultii, moderate ridgei, in which the first distance was larger than
deflection in R. amplexicaudatus and R. spinalatus, the second (0.7 and 0.2, respectively). The post-
while inall otherRousettus species itis strong. As a glenoid process is an ill-defined process and the
character to distinguish these genera,brain-case different results may wellbe causedby a different
deflection has no apparent value. (See also the method of measuring a distance from that
account ofRousettusin Bergmans, 1994.) process to anotherpoint. But the calculatedvalue
The anterior part of the skull in Lissonycteris must be considered a doubtfulmeasure ofbrain-
(see Lawrence et ai, 1963) is relatively longer case elongation anyhow. When calculating the
than in all Rousettus species except lanosus and percentage of cbl of the brain-case length (mea-
madagascariensis, and Myonycteris torquata. However, sured from the medianpoint on the connecting
this relation is difficult to ascertain; one has to line between the dorsal ends of the distinct
work with projected lengths, with skulls showing grooves in the orbits that mark the anterior limit
different measures ofdeflection. of the brain-case proper, to the posteriormost
15
to determinethe anterior measuring point reli-
ably, and thedifferencefoundis minimal.
A typical characteristic not noted before is
that the upper alveolar line in Lissonycteris and
Myonycteris changes inlevel anddirectionbetween
P3and P4. This brings on a differentshape of the
rostrum if compared with Rousettus, with a low
distal partwithnearly parallel dorsalside andlat-
eroventral margin anterior to P4 (figs. la-c). The
mandibularalveolar line does not correspond to
this level change but remains ratherstraight, and
the resulting local divergence accomodates the
relatively highpremolars andanterior molars.
Lawrence et al. (1963) drew attention to the
characteristic occlusion pattern inLissonycteris and
Myonycteris, with alternating P3 and P and with
;i
P3 and P4 barely occluding with P4. To this may
be added that P4has shifted outward, as farasP3.
In Lissonycteris this pattern is very distinct and in
Myonycteris torquata it is essentially the same. InM.
brachycephala and relicta these teeth are relatively
heavier and not as distant from one another.
These species do, however, show the same trend
toward widely spaced anteriorcheek-teeth. In
Rousettus species none of the above characters is
found. The thirdpremolars are slenderbutnot as
thin as in Lissonycteris; moreover, they are nearer
to eachother(P3/P3)and nearer to C1 (P3)andP4
(P3). The fourthpremolars are relatively heavier,
less pointed, and longer than those in Lissonycteris
and occlude with eachother andwith P3 (P )and
4
M, (F).
The relative anterior rostrum height in Lisso-
nycteris and Myonycteris is smaller than in all Rou-
settus species except madagascariensis and obliviosus.
In madagascariensis this height is even smaller than
inLissonycteris. Lawrenceetal. (1963) notedthat in
Lissonycteris and in Myonycteris the nasals are de-
Fig. 1. Rostra. Lateral view ofa: Lissonycteris angolensis ango-
pressed posteriorly, while in Rousettusthey are not.
lensis (Bocage, 1889), ￿ from Pointe Noire, Congo (ZMA
15.537); b: Myonycteris torquata (Dobson, 1878),￿ from Thiscontributes to a relatively low posterior ros-
Pointe Noire, Congo (ZMA 15.423); c: Rousettus egyptiacus trum in the former two genera(figs, la-b), al-
egyptiacus (É. Geoffroy-St. Hilaire, 1810), ￿ from Cairo, though it is difficult to quantify.
Egypt(ZMA 22.205). The anterior palate is slightly narrowed in
Lissonycteris, and somewhat more in Myonycteris;
the upper tooth-rows appear to be constricted
from P3 on forward. In most Rousettus the tooth-
point on the occiput), Lissonycteris has a slightly rows are converging but straight, except in
shorter brain-case than all Rousettus species amplexicaudatus in which they are also a bit con-
(59.7% of cbl, against 61.6-68.8% in Rousettus; cave and in R. bidens in which they are straight
Myonycteris torquata: 65.1%). It is difficult, however, but hardly converging.
16
In all Lissonycteris specimens the premaxillae rostral margin and related it to the lachrymal
are co-ossified, in Rousettusspecies except the odd width. But the lachrymal width itself is not with-
old R. e. egyptiacus and in Myonycteris torquata they out interspecific variation. In Lissonycteris and
are not. In the holotype specimen of M. relicta Myonycteris, where the orbit was found to be
they are not, but in a specimen from Zimbabwe largest, the rostrum is relatively lowand narrow,
they are. The ascending branchesofthepremax- whilein mostRousettus species it is not (exceptions
illae are of a generally heavier built in Rousettus are R. madagascariensis and some R. amplexicauda-
than in Lissonycteris and Myonycteris (fig. la-c), but tus). Presently, the distance was measured be-
in some species the difference is trivial or non- tween a point directly beneath the postorbital
existant (e.g. R. spinalatus). process and the approximate opposite, deepest
Andersen (1912: 814) wrote that Lissonycteris point of the caudal side of the zygomatic arch,
hasarelatively longer postdental palate than typ- and related to cbl and to brain-case length (bcl;
ical Rousettus. Ofthe species Andersenexamined, measured as describedabove). According to this
only R. celebensis has a convincingly shorter post- method, Myonycteris torquata has the relatively
dentalpalate (related to cbl andpi). InR. egyptia- largest orbit (29.5% of cbl; 45.3% ofbcl). In two
cus and R. leschenaultii shortridgei its relative length examples of M. relictait is 25.0 and 26.3% of cbl,
is about equal to, or slightly larger than, that in respectively (bcl not available). On M. brachycepha-
Lissonycteris, in R. amplexicaudatus and typical R. lathere are no data, butmeasurements in Ander-
leschenaultiiabout equal or slightly shorter. R. lano- sen (1912: 584) indicate that the relative size of
sus and R. madagascariensis have relatively longer the orbit is also smaller than in M. torquata. In
postdental palates, and obliviosus and spinalatus Rousettus relative orbit size also varies: R. leschen-
have relatively shorter ones thanLissonycteris. In aultii shortridgei has the largest (25.5% of cbl;
R. bidens it is somewhat shorter ifrelated to cbl 40.8% ofbcl) andR. celebensisthesmallest (22.3%
but longer ifrelatedto pi. of cbl; 34.0% of bcl). Lissonycteris (23.7% of cbl;
To judge from the external appearance, the 39.7% ofbcl) falls within the variation range of
lateral frontal sinuses in Lissonycteris and Myonyc- Rousettus, although the bcl percentage is among
terisare more inflated than the medial ones. This the highest.
is accentuatedby the low rostrum. In Rousettus The antero-ventral border of the orbit is a
egyptiacus and typical leschenaultii the sinuses are rather thin and sharp-edged rim in Lissonycteris
much less pronounced, atleast externally, but the and Myonycteris, but not much less so in Rousettus
lateral pair is slightly more inflated. In R. bidens leschenaultiiand madagascariensis. Theanterior part
the lateralpair is prominent, themedialpair less. ofthe zygomatic arch is generally flatter in the
In R. lanosusthe lateralpair is also the most pro- former two genera, and rounder (in section) in
minent but the differencewith the medial pair is most Rousettus (not in typical leschenaultii). As the
less than in R. bidens. In R. madagascariensis, oblivio- root of the arch widens towards the skull, the
sus, leschenaultii shortridgei and spinalatus the two length of the infra-orbital canalrather depends
pairs of sinuses are aboutequally inflated. In R. on theangle underwhich this root joins theskull.
amplexicaudatus and celebensis the medial pair tends Thisangle variesbut I have foundno convincing
tobemore inflated than thelateralpair. differences between thegenera.
The interorbital skull roof in Lissonycteris and The posterior zygomatic arch insertion in
Myonycteris is slightly concave. InRousettus bidensit Lissonycteris and Myonycteris is more distal than in
is very weakly concave. In R. egyptiacus malesit is most Rousettus species, as dorsal skull views show
weakly concave, in females and in both sexes of In strongly deflected skulls theposition of thegle-
R.amplexicaudatus and leschenaultiiit is flat to weak- noid fossa in relation to the tympanic bullaoffers
ly convex. In R. celebensis it is about Hat. In R. abetter meansto check this. However, R. amplexi-
lanosus, madagascariensis, obliviosus andspinalatus it is caudatus, bidens and spinalatus do not differ very
slightly convex. much, in thisrespect, from theothertwo genera.
Thereappears to be no objective way to mea-
sure the relative size ofthe orbit. Lawrence et al.
(1963) took its diameter parallel to the antero-
17
Dentition with a - weak but distinct - inner cusp; in this
species, the maincusp is placed more toward the
The larger premolars and molars in Lissonycteris labial side, and the anterior and posterior upper
are relatively short, antero-posteriorly, squarish in surfaces are not directed lingually but forward
outline, and with large interstices, especially be- andbackward, respectively.
tween canines and premolars. In Rousettus these P4 in Lissonycteris is squarish in outline, has a
teeth are essentially oblong, even though quite distinct outer and a distinct inner cusp, both
broad and nearly squarish in some species (bidens, slightly anterior to the middleand mutually con-
spinalatus), with smaller interstices - except lanosus, nectedby a concaveloph, anda distinct but weak
with its reduced dentition. In Myonycteris, torquata postero-basal ledge. InMyonycteris torquata andM.
comes nearest to Lissonycteris (see Andersen, 1912, brachycephala, P4 is more rectangular and has
fig. 47), brachycephala resemblesLissonycteris in teeth weaker, lowercusps, aweakantero-basal andstill
outlines but its teeth are large and hence the weaker postero-basal ledge. In M. torquata the
interdental spaces small (Andersen, 1912, fig. 47; anterior surface has a weak longitudinal ridge
this paper, fig. 7a-d), and relicta has relatively long and thereis arudimentofwhat appears an ante-
teeth but nevertheless shows the same tendency ro-internal cusp. In M. relicta, the outer cusp is
towards larger interstices as torquata (Bergmans, low but distinct, the inner is a mere vaultin the
1980, figs. 1-2). Andersen's(1912) remark that in inner ridge; the whole tooth is placed rather
Myonycteris both upperand lower fourth premo- obliquely in the row, with its anterior side direct-
lars and first molars are shorter than in Rousettus ed inward. In Rousettus egyptiacus P4 is relatively
do not apply to M. relicta. longer, with stronger outer and inner ridges and
In Lissonycteris and Myonycteris torquata and forward-placed cusps; the distinct but low outer
brachycephala C1 has a different form and orienta- cusp formspartofthe outer ridge; the innercusp
tion than inRousettus. Inthe former, itisrelatively is a much lower but thicker part of the inner
lower, more strongly hook-shaped, with a rudi- ridge, opposite the outer cusp. The innerridge
mentary postero-basal shelf; the postero-internal shows a vestigial antero-internal cusp and a low
side is directedbackward rather than inward. In but distinct postero-internal cusp. In other Rou-
Rousettus it is high, without postero-basal shelf, settusspecies P4 isessentially the same.In R. lesche-
and laterally more or less depressed (with nearly naultiitheinnercusp is placed more forward.The
flat labial and lingual sides in amplexicaudatus, cusps may be somewhat weaker (amplexicaudatus,
bidens and celebensis); the postero-internal side is leschenaultii, madaguascariensis,' obliviosus)/ to veryJ
directed inward rather than backward. In Myo- weak, with littleor no further diversification of
nycteris relicta it is low, but its orientation and pos- the innerridge (ibidens, celebensis, lanosus, spinalatus).
tero-basal detailsare ratheras inRousettus. In R. spinalatusP4 is verybroad.
Thebasal outlineofP> inLissonycteris is rather In Lissonycteris, M1 is aweakenedversionofP4,
symmetrical, short, sub-oval. Its postero-internal and M-a furtherweakenedformofM1. M1 has a
side is directed backward. Its tip is pointed and very weak inner cusp which is scarcely higher
placed labially. It has no postero-basal shelf. In than its commissure with the outer cusp. The
Myonycteris torquata it is shorter, and in all three outer cusp in M2 tends to point forward. In
Myonycteris species the tip is more lingual and Myonycteris, M1 is also aweakenedformof P4. M-
there is a weak postero-basal shelf. In Rousettus is very small, roundish, with a ridge all around
egyptiacus P3 has a different basal outline, with a but without cusps. In Rousettus egyptiacus M1 also
muchnarrower posterior side. Its tip is less point- resembles a weak P1 although it may be a trifle
ed and placed more inward, and there is a rudi- longer. The maincusps are placed near the front,
ment of a second, internal cusp on the internal the inner cusp at the antero-internal corner.
keel running from tip to base. In other Rousettus There is an equally-sized postero-internal cusp.
species the basal outline ofP:i is essentially the In M2the outer cusp isweak, there is only avesti-
same, except lanosus and madagascariensis inwhich gial antero-internal cusp, and a more pronounc-
P:i is laterally depressed, and bidensin which it is ed postero-internal ct sp. In R. leschenaultii, mada-
not narrowed. R. bidens is the only other species gascariensis and obliviosus these molars are essen-
18
tially as in R. egyptiacus. InR. amplexicaudatus they rior side thickened at its base, its almost flat pos-
are furtherdegenerated, withlow (M1) or no (M2) terior side turned slightly outward, and a narrow
innercusps. In theotherRousettus species they are postero-basal shelf. In Myonycteris it is relatively
also less differentiated, to various extents. lower than in Lissonycteris, with its tip a bit more
The lower incisors are bilobed in Lissonycteris, backward, and a wider postero-basal shelf. In
Myonycteris and most Rousettus. InM. torquata this is Rousettus egyptiacus it is relatively heavier and
_
less distinct inI2. InR. lanosus the lobesare weak, lower thanin Lissonycteris, with a weakly keeled
in R. spinalatus they are vestigial, in R. bidensthey and more strongly recurved anterior side, a
are lacking. In all three genera there is little size slightly inward-directed posterior side, and a
difference between I, and I2, except in R. bidens, wider postero-basal shelfwith a ledge which is
in whichI2is three to fourtimesthe bulk ofI,. thickened at the postero-internal corner. In most
In Lissonycteris C, is a low, outward-pointing otherRousettus species it is much the same butlat-
,
simple tooth, scarcely higher than P;5; there is a erally depressed, lower,and usually less differenti-
slight angle between antero-external and antero- ated.
internal faces, a distinct vertical ridge with at its P4 in Lissonycteris is the largest of the cheek-
posterior side a parallel groove between antero- teeth, longer than P:i and longer but hardly
external and posterior faces, and a rudimental broaderthanM,. It hasa broad, blunt outer cusp
postero-basal shelf. InMyonycteris torquata C, is rel- just before the middle, and an innerridge ending
atively smaller, less outward-directed, with none in a rather high, somewhat transverse, free-
of the characters mentioned further for Lissonyc- tipped innercusp, anterior to the outer cuspand
teris. In M. brachycephala C, is lower than P3; in connected with it by a concave commissure. The
both this species and M. relicta C, is relatively tooth is narrowed anteriorly, thickened at its
simple but has a narrow postero-basal shelf. In anterior base, and ends in a weak postero-basal
Rousettus egyptiacus C, is relatively much bulkier, ledge. In Myonycteris torquata P4 is relatively large,
especially inwidth, than inLissonycteris. Itis clear- longer and broader than both P, and M,. Mor-
ly higher than P3and has allthe characters men- phologically it is a much weakenedversion ofP4
tioned for Lissonycteris be it less pronounced. In in Lissonycteris; it is lower and little differentiated,
,
the other Rousettus species, those characters are with the innercusp reduced to amere 'shoulder'
present to a varying extent, but usually weaker in the innerridge where it curves inward and
than in R.egyptiacus. In R. amplexicaudatus thepos- upward to join the outer ridge and cusp. In M.
tero-basal shelf is practically lacking. In R. bidens brachycephala P4 is also the largest toothofthe row
C! has turnedoutward: what in other species is and morphologically much as inLissonycteris, with
theantero-external face hasbecome the external diverging outer andinnercusps. InM. relicta P4is
face, and other faceshave shifted accordingly. Its the largest ofall teeth, long (antero-posteriorly),
basis is clearly longer thanwide. Its tip is strongly with a broad outer cusp and no inner cusp. In
bentoutward. InR. celebensis, C| is quite similar. Rousettus egyptiacus P is broader than P and
4 3
Pi is very small, with a distinct outer cusp, in slightly broader thanM, but neitherin this nor in
Lissonycteris. It is slightly larger in surface but not otherspecies ofRousettus itis particularly large. In
very different in shape in Myonycteris torquata and R. egyptiacus it is a heavy, sub-rectangular tooth
brachycephala, about 1.5 times larger in M. relicta, with thick outer and inner ridges, a broad blunt
and much larger and variable inshape in Rouset- outer cusp placed near the anterior end, the
tus: 3-4 timesinmadagascariensis, 4-5 timesinegyp- inner ridge bending inwardand forming ashoul-
tiacus, amplexicaudatus, lanosus, typical leschenaultii, der before joining the outer cusp. The posterior
obliviosus and spinalatus, and about 6-7.5 times in surface is strongly concave. In other Rousettus
bidensand celebensis. In all Rousettus species P, has a species, P4 varies on this pattern. In most, outer
distinct outer cusp andis aboutas wideas long in and inner ridges and cusps are reduced in height
all species except bidens, celebensis and madagas- ifcompared to egyptiacus, in some the cusps are
cariensis in whichit is distinctly longer than wide. placed more backward (especially in bidens and
P( in Lissonycteris is a relatively simple, rather madagascariensis, but also in lanosusand, to a lesser
blunt-tipped, short tooth, with the rounded ante- extent, in some others). In R. bidens, celebensis,
19
madagascariensis and spinalatus the whole tooth is samples ofthe generaunderdiscussion are small,
very low,and thecusps are largely rudimentary. the conclusions must be preliminary. Thebacula
The first to third lower molars in Lissonycteris of adult Lissonycteris and Myonycteris appear to be
are sub-rectangular in outline, allhave outer and morphologically related, while African mainland
inner ridges, passing into anterior and posterior Rousettus (i. e. egyptiacus and lanosus) are more dis-
ridges. The broad, blunt outer cusps are placed tant (figs. 2a-f). The shape in R. egyptiacus (fig. 2e)
anterior to the middle (M,) or atthe middle(M2, is very simple. It has been figured earlier by
M3), and decrease in height with the overall size Harrison (1964; R. e. arabicus), Didier(1965; R. e.
of theteeth, from M, to M3. The inner cusps are leachii) and Madkour (1976; typical subspecies).
reduced to broad upward curves of the inner The specimens of Harrison and Madkour both
ridges. The upper surfaces are flat except for the show asmall proximal incurvationbut otherwise
outer quarter which slopes upward to the outer agree fairly well with the present specimen.
cusp. In Mj a distinct ridge runs from the cusp Didier's specimen is less slender but equally sim-
tip to halfway its innerface, in M2 and M3 there ple. Most apparent in these egyptiacus bacula is
are less pronounced to vestigial ridges. Theouter the almost complete absence of digital lateral
cusps in M2 and M3 lean outward. In Myonycteris wing-like projections. Thebaculum ofR. lanosus
torquata M, is more oblong than inLissonycteris. Its has small wings (fig. 2f); the figured specimen is
low outer cuspand theupward curve in theinner fully adult and this may be the ultimate adult
ridge are placed near the anterior side. The condition. Krutzsch (1959; 1962) described and
ridges and cusp are less sharp thanin Lissonycteris. figured bacula ofR. a. amplexicaudatus (in 1959as
M2 and M3 are sub-rectangular, M2 slightly nar- R. a. brachyotis (Dobson, 1877) and in 1962 as R.
rowing towardstheback, witharidge all around. a. minor (Dobson, 1873)), R. a. infumatus (Gray,
The outer ridge is slightly higher than the inner 1870) (as R. a. amplexicaudatus), and R. leschenaultii
but there are no cusps. In M. brachycephala these shortridgei. Bhatnagar (1967) describedand fig-
molars are about the same, only wider. In M. ured abaculum oftypical leschenaultiifrom North
relicta M, is long, narrow, and low, with the outer Malacca, Agrawal et al. (1973) did so for speci-
ridge higher than the inner, atrace ofan antero- mens ofamplexicaudatus from India orBurma and
median outer cusp and ofa commissure to the leschenaultii from India, and Martin (1978) gave
lingual ridge. M2is not differentiated. There is no descriptions and figures ofbacula of a juvenile
M3. InRousettus egyptiacus M,-M3 are heavy, ob- and threeadult typical leschenaultii, the adults of
long, relatively high teethwith thick ridges all different ages, from the same North-Malaccan
aroundbut for tiny incurvations at the short sides locality as Bhatnagar's specimen. R. amplexicauda-
in M| and M2, the outer ridge somewhat higher tus has wing-like projections ofvariable size, pos-
than the inner, and both ridges highest at the sibly connected with age, and a proximal incur-
anterior side but without real cusps. The upper vation in two of the three figured specimens.
surfaces are concave. M, is the largest, M3 the According to Martin (1978), R. l. leschenaultii
shortest tooth. Other Rousettus species have the exhibits age and individual variation; with age
same bath-tub type teeth or less differentiatedto the baculum becomes larger and develops distal
degenerated forms thereof. In R. bidens they are headand proximal wings, but in one of his two
almost flat, without ridges, and vestiges of cusps oldest specimens it is an undifferentiated oblong
only in M,. InR. celebensis they are low, with con- bone, not unlike those of R. l. shortridgei and R. l.
cave surfaces, Mj and M2 with or without traces leschenaultii figured by Krutzsch (1962) and
of cusps. In R. spinalatus these molars are Bhatnagar (1967), respectively - which by their
approaching those ofbidens inshape. size are also adult specimens -, and, indeed, not
unlike the knownexamples ofR. egyptiacus. (It can
not be excluded that Martin's winged specimens
Bacula represent amplexicaudatus instead ofleschenaultii, as
both species occur in northern Malacca; this
Bacula arc subject to age and (possibly) individ- would explain the extreme variationencountered
ual variation (Martin, 1978). As the available by him and whichappears tobe quite exception-
20