A survey of the dragonfly fauna of the Malay Peninsula, with notes on that of neighbouring countries. Part II
F. F. Laidlaw’s 1924 paper, published in the Journal of the Malayan Branch of the Royal Asiatic Society, constitutes the second part of a systematic survey of the damselfly (Zygoptera) fauna of the Malay Peninsula and neighbouring regions. Working from museum collections and field specimens gathered across the Peninsula, Borneo, Sumatra, and Java, Laidlaw treats four sub-families—Epallaginae, Amphipteryginae, Megapodagrioninae, and Platystictinae—providing diagnostic characters, species descriptions, and a distributional table that together form a foundational reference for the region’s odonate biodiversity.
Summary
The paper opens with the Epallaginae, the most speciose and visually striking of the groups treated. Laidlaw divides Pseudophaea into four species-groups (ochracea, variegata, masoni, and dispar), each characterized by distinct wing colouration patterns in males and differing degrees of hind-wing specialization. The variegata group, confined to the Malay Peninsula, Borneo, Sumatra, and Java, is highlighted as producing “amongst the most brilliant of oriental insects,” with Borneo holding the richest representation at four species. Laidlaw also discusses Dysphaea, a genus of long-winged, darkly patterned damselflies, distinguishing two Malayan species (lugens and dimidiata) on the basis of wing dimensions and the extent of basal colouration, while noting considerable individual variation that complicates specific boundaries.
The Amphipteryginae and Megapodagrioninae are treated more briefly, as each contains only one or two Malaysian genera. Devadatta argyrioides is noted as the sole representative of the Amphipteryginae in the region, typically encountered at 1000–2000 ft elevation. The Megapodagrioninae are represented by Podolestes (two species) and Rhinagrion (five or six species), the latter being a highly specialized genus with striking green, orange-brown, and black coloration. Laidlaw draws attention to a remarkable case of apparent mimicry in Hainan, where Pseudolestes mirabilis resembles the unrelated Pseudophaea decorata.
The Platystictinae receive the most extensive treatment in terms of generic architecture. Laidlaw establishes the genus Drepanosticta (with D. carmichaeli from Darjiling as genotype) and distinguishes it from Protosticta on the presence or absence of a cross-nerve descending from the anal border of the quadrangle. He describes or discusses several Peninsula and Bornean species, including D. quadrata, D. sharpi, and a new unnamed form from Jor, Perak, collected by F. N. Chasen, whose bizarre male anal appendages are figured on Plate V. The genus Protosticta is characterized by extreme abdominal elongation relative to wing length, with P. forsteri from the Peninsula known from a single female type and a presumably conspecific male. The paper closes with a distribution table mapping all treated species across the Malay Peninsula, Borneo, Sumatra, Java, and other localities, and with corrigenda to Part I.
Key Findings
- Pseudophaea ochracea, the smallest species of its group, has a hind-wing of 27.5 mm and ranges from Malacca north to Patani; the male’s hind-wing is uniformly golden yellow (p. 297).
- The variegata group of Pseudophaea is richest in Borneo with four species; P. variegata has a hind-wing widened to 9 mm at its broadest, while P. aspasia reaches only 6.5–7 mm (p. 298).
- Dysphaea lugens measures 32–34 mm in hind-wing length and 41 mm in abdomen; D. dimidiata is smaller at 30 mm hind-wing and 36 mm abdomen, with basal wing markings stopping short of the nodus in the fore-wing (p. 300).
- Podolestes orientalis possesses 19 or more post-nodal cross-nerves (Kruger records up to 23), whereas P. chrysopus has only 15–18; the former has an olive thorax with black lateral bands, the latter an entirely bronze-black thorax (p. 302).
- Drepanosticta sharpi from Jor, Perak, has an abdomen of 45 mm and hind-wing of 25 mm, with the hind-wing reaching the middle of the fifth abdominal segment; a new unnamed species from the same locality has an abdomen of 30 mm and hind-wing of 18.5 mm (pp. 304–305).
- Protosticta forsteri, known from a single female type collected by Laidlaw at Kuala Aring, Kelantan, and a male from Jor, Perak, has a hind-wing of approximately 17.5 mm against an abdomen of 38 mm in the male (p. 306).
Conclusion
Laidlaw’s survey establishes a working taxonomy for the Zygoptera of the Malaysian region at a time when the fauna was still being assembled from scattered museum lots and field collections. His emphasis on wing venation, anal appendage morphology, and colour pattern as diagnostic tools, combined with the distributional table, provides a framework that subsequent workers could test and refine. The paper also flags numerous gaps—undescribed species, single-specimen taxa, and unresolved synonymies—that underscore how incomplete the regional fauna remained even by the mid-1920s.
Context
- Laidlaw was a British entomologist working in the colonial scientific establishment; his specimens derive from collectors operating under the administrative infrastructure of British Malaya (e.g., Waterstradt, Chasen, Annandale), and the paper reflects the museum-based, collection-driven methodology typical of early twentieth-century colonial natural history.
- The study draws primarily on the British Museum (Natural History) collections and the Raffles Museum, Singapore, with field material from the Peninsula, Borneo, and Sumatra. Its historiographical contribution lies in providing one of the first comprehensive, regionally bounded treatments of Malaysian damselflies, establishing generic and species-group concepts still referenced in subsequent odonate literature.