Am 19. Mai 1981 wurde meine Dissertation über den Javanischen Silbergibbon von der Philosophisch-Naturwissenschaftlichen Fakultät der Universität Basel gutgeheissen. Die Arbeit befindet sich als Typeskript in der Basler Universitätsbibliothek und kann dort eingesehen werden. Hier der Anhang mit dem Titel «Former and Presentday Problems in Nomenclature and Taxonomy of the Javan Gibbon» im Wortlaut:
Former and Presentday Problems
in Nomenclature and Taxonomy of the Javan Gibbon
© 1981 Markus Kappeler
When reviewing the literature on gibbons, it is found that a variety of different names have been used for the Javan gibbon and, moreover, that some of these names have been applied also to other gibbon types. For these reasons, it is sometimes difficult to ascertain whether a certain statement actually refers to the Javan gibbon or not.
In the following, an attempt to clarify the situation is made by (1) presenting the reasons for this confusing situation, and (2) giving a list of the different names in the synonymy of the Javan gibbon.
Although grey coloured gibbons had already been briefly mentioned by LECOMPTE , SCHREBER , CAMPER  and PENNANT , efforts to define the taxonomic position of the grey gibbon type did not take place until the very end of the 18th century when three separate names were given to it almost simultaneously:
Simia moloch by AUDEBERT in 1798 (plate and description; not «1797» [CABRERA, 193O]),
Simia cinerea by CUVIER in 1798 (description only),
Simia leucisca by SCHREBER in 1799 (plate only; year of publication according to SHERBORN ).
During the following century - after it had become known that not only one grey gibbon type existed, but that (1) grey coloured gibbons occurred on Borneo as well as on Java, and that (2) the Javan and the SE-Bornean type differed from the NW-Bornean one in having a marked black «cap» (dark crown hair) - discussion arose as to which of these three gibbon types the above mentioned names had actually been given.
Reasons for the uncertainty were the following:
AUDEBERT mentions «les Moluques» as place of origin; neither plate nor description give any indication of a black cap.
CUVIER mentions «Batavia» (= Jakarta) as place of origin, but does not describe a black cap either.
SCHREBER's illustration lacks any reference as to the origin of the animal shown; although he had mentioned a black cap in his publication of 1775, this can not be recognized from the illustration of 1799.
Despite this uncertainty, most zoologists subsequently assumed that all three authors had been referring to the Javan gibbon.
MATSCHIE [1893a] however was convinced that AUDEBERT'S and SCHREBER'S names (CUVIER's publication is not considered by MATSCHIE) have to be used for the gibbon of NW-Borneo, this being the only one without a black cap, and proposed to name the Javan gibbon type «javanicus». (It seems unlikely indeed that AUDEBERT should have «forgotten» to indicate on his excellent engraving the black cap of the Javan gibbon provided that he really portrayed this gibbon type.)
However - as is stated by GROVES [1971,1972] - MATSCHIE's point of view was not accepted; moloch AUDEBERT 1798 is used as the earliest valid name for the Javan gibbon, cinerea CUVIER 1798 and leucisca SCHREBER 1799 as its first synonyms.
Around the turn of the century, the question arose whether the Javan gibbon was an independant species or a subspecies, and accordingly whether «moloch» had species or only subspecies status.
Since two gibbon types can largely correspond in one characteristic (morphological or ethological), but can very much differ in another, it is problematic how (i.e. from what characteristics) the degree of relationship between gibbons must be concluded. In attributing the greatest taxonomic relevance to varying characteristics, different authors arrived at different possibilities of classifying the Javan gibbon.
In general, three ways of arranging the Javan gibbon within the genus have been chosen:
1. as full species [e.g. by ANDERSON, 1881; MATSCHIE, 1893b; ELLIOT, 1912],
2. as conspecific with the Bornean gibbon types [e.g. by FORBES, 1894; KLOSS, 1929; SCHULTZ, 1933; CHASEN, 1940; NAPIER & NAPIER, 1967; CHIARELLI, 1972],
3. as a geographically isolated subspecies of the polytypic species lar [e.g. by POCOCK, 1927; SODY, 1949; SIMONETTA, 1957; GROVES, 1972].
The most comprehensive and thorough discussion of the taxonomy of the whole genus Hylobates has been published by GROVES . It includes and evaluates all kinds of taxonomic evidence. In his classification, moloch appears as a subspecies of Hylobates lar, at the side of mülleri, abbotti, agilis, vestitus, lar, entelloides and carpenteri.
SODY  distinguished two races of the Javan gibbon: H. lar moloch from West Java and H. lar pongoalsoni from Central Java. When examining gibbon skins, he found that the cap of specimens (infants included) from West Java was regularly much darker than in specimens from Central Java, and subsequently based his concept on this difference.
According to GROVES [1971,1972], such difference in colouring is merely due to individual and/or age variation, not geographic variation.
During a 20-month study period, the present author could not detect any dark-capped gibbon infants in West Java; and in Central Java, gibbons showed quite marked dark caps. Furthermore, the pattern of the great call (which is subject to distinct subspecific differences and can therefore be used as taxonomic evidence [MARSHALL & MARSHALL, 1976]) uttered by female gibbons from Central Java did not differ from that of West Javan females.
Therefore, the subspecific separation mentioned does not seem to be justifiable.
The different names in the synonymy of the Javan gibbon are successively as follows:
Simia moloch [AUDEBERT, 1798], Simia cinerea [CUVIER, 1798], Simia leucisca [SCHREBER, 1799], Pithecus cinereus [LATREILLE, 1804], Pithecus leuciscus [GEOFFROY, 1812], Hylobates leuciscus [KUHL, 182o], Hylobates javanicus [MATSCHIE, 1893a/1893b], Hylobates lar leuciscus [POCOCK, 1927], Hylobates cinereus cinereus [KLOSS, 1929], Hylobates moloch [CABRERA, 193O], Hylobates moloch moloch [CHASEN, 194O], Hylobates lar moloch & Hylobates lar pongoalsoni [SODY, 1949].
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