Dragonflies and damselflies in Cross River State, Nigeria (Odonata)

This report presents the results of a 17-day Odonata expedition to Cross River State, southeast Nigeria. The rainforest and highland habitats of this state and adjacent parts of Cameroon are thought to support the highest diversity of Odonata in Africa, with a particularly high share of threatened and range-restricted species. Nevertheless, field surveys in this region have been very scarce in recent decades, and knowledge from the Nigerian territory lags behind that from Western Cameroon. Yet, a growing interest in Odonata among Nigerian ecologists is now creating opportunities for increased survey effort in this region. A collaboration between Nigerian and Dutch students resulted in an extensive exploration of freshwater habitats across Cross River State during the dry season in January-February 2022. This team visited four locations in Cross River State, exploring diverse running waters and occasionally stagnant waters both in legally protected forests and in adjacent humaninfluenced landscapes. Three locations fell into the lowland rainforest zone in the Cross River National Park – Oban Section (Aking & Ekang) and Afi River Forest Reserve (Buanchor), while the fourth represents the highland habitats of the Obudu Plateau (1200-1700 m a.s.l.). Sampling emphasis was on rare and little-known Odonata, and special attention was paid to specimen collection and in-situ photography. The survey recorded 138 taxa, of which (preceding DNA-barcoding) 123 could be identified to species level, confirming the exceptional Odonata diversity of this region. These species represent twelve new national records for Nigeria, and three species new to science: a Tetrathemis species from Aking resembling the West African T. godiardi, and Atoconeura and Neodythemis species from the Obudu Plateau. 11 species were photographed in the field for the first time, including range-restricted species such as Allocnemis vicki, Neurolestes nigeriensis, Umma purpurea and U. mesumbei. Furthermore, extensive photographic material provided further insight in the extraordinary colour transformations of Africocypha lacuselephantum and A. centripunctata males and females. The highest local species diversity was observed at streams in the lowland sites of Aking and Ekang, while sites with limited disturbance at Buanchor and the Obudu Plateau also had a relatively high species diversity. High diversities of Zygoptera, notably Calopterygidae and Platycnemididae, were recorded at forested streams, while sites with some human disturbance were richest in Libellulidae. Specialized relict species were recorded in small seepage-fed streams at Aking (Neurolestes trinervis, Pentaphlebia stahli and Stenocnemis pachystigma) as well as at the edge of the Obudu plateau at 1200 m a.s.l. (P. stahli and S. pachystigma). Well-preserved highland streams on the Obudu plateau supported a small but distinct assemblage of specialized species including A. vicki, N. nigeriensis and Nubiolestes diotima. It was in this habitat that Pentaphlebia gamblesi was collected in 1973. We could not find adults of this little-known species, which was a major target of the expedition, but collected larvae of Pentaphlebia spec. at two sites. As the mystery surrounding P. gamblesi persists, many other promising areas remain unexplored, and an even greater species diversity (notably of Gomphidae and species of ephemeral waters) is expected during the rainy season, the scope for further exploration of Cross River State’s Odonata remains. Widespread habitat degradation, especially on the Obudu plateau, increases the urgency of further research and conservation efforts in this region.