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From "Entirely Yellow" to "Yellow": Ploceus holoxanthus

2016-01-25 (694)

Ploceus holoxanthus was described by Hartlaub (1891) and the name means "Entirely Yellow" (Greek: holos, complete, entire; xanthos, yellow). Later this taxon was considered to belong to the Eastern Golden Weaver Ploceus subaureus, commonly known as Yellow Weaver (at least in southern Africa).

Ploceus holoxanthus, or Ruvu Weaver, is now thought to be a valid species (see news). So why was it not initially kept as a separate species?

Important changes to the taxon Ploceus holoxanthus:

Author Notes
Hartlaub 1891 described new species; Reichenow saw the type and agreed with Hartlaub that it was new; Sharpe and Shelly saw it briefly and were hesitant to consider it separable
Reichenow 1894 gave a brief summary of the species, still keeping it separate
Reichenow 1904 now treated it as a synonym of Ploceus aureoflavus [=subaureus] - Reichenow appears to have had a single specimen that he looked at, and he considered that it was a mature phase of Eastern Golden Weaver
Shelley 1905 referred to Reichenow 1904 but nevertheless considered holoxanthus to be unique, apparently based on 4 specimens, 2 males and 2 females; Shelley provided a plate of a male
Hartert 1907 also considered holoxanthus as distinct, based on plumage and measurements of 2 specimens, a male and a female
Zedlitz 1916 argued that Reichenow [1904] was correct; Zedlitz looked at a series of specimens, mostly from the Berlin Museum - however, it is not clear if he actually studied any holoxanthus specimens
Hartert 1919 now agreed with Zedlitz 1916, as Hartert thought Zedlitz had studied a greater series of specimens

So Sclater 1930 and other subsequent authors simply considered holoxanthus as a synonym of Eastern Golden Weaver.

The basic problem is that the Ruvu Weaver is similar to Eastern Golden Weaver, and few Ruvu Weaver specimens were known.

phown 18520
Ruvu Weaver male,
figure from Shelley 1905

References

Hartert E 1907 Notes on African birds. Novitates Zoologicae 14:484-503.
Hartert E 1919 Types of birds in the Tring Museum. B. Types in the general collection. I. Corvidae to Meliphagidae. Novitates Zoologicae 26:123-178.
Hartlaub G 1891 Vierter Beitrag zur Ornithologie der ostlich-äquatorialen Lander und der ostlichen Kustengebiete Afrikas. Abhandlungen der Naturwissenschaftlichen Vereins zu Bremen 12: 1-46.
Reichenow A 1894 Die Vogel Deutsch-Ost-Afrikas. Geographische verlagshandlung Ditrich Reimer, Berlin.
Reichenow A 1904 Die Vogel Afrikas. Band 3. 1904-05. J Neumann, Neudamm.
Sclater WL 1930 Systema Avium Aethiopicarum. Vol. 2. British Ornithologists' Union, London.
Shelley GE 1905 The birds of Africa, comprising all the species which occur in the Ethiopian Region. Vol. 4, Part 2. RH Porter, London.
Zedlitz OG 1916 Das Süd-Somaliland als zoogeographisches Gebiet: Eine ornithologische Studie. Journal fur Ornithologie 64: 1-119.