Aeshna (Adversaeschna) brevistyla caledonica Davies, 2002

Grand, Daniel, Marinov, Milen, Jourdan, Herve, Cook, Carl, Rouys, Sophie, Mille, Christian & Theuerkauf, Jörn, 2019, Distribution, habitats, phenology and conservation of New Caledonian Odonata, Zootaxa 4640 (1), pp. 1-112 : 42-45

Aeshna (Adversaeschna) brevistyla caledonica Davies, 2002

( Fig. 39 )

Aeshna brevistyla Rambur, 1842 ; Aeshna lineata Tillyard, 1916 ; Aeshna oblita Tillyard, 1916 ; Adversaeschna brevistyla caledonica Davies, 2002: 231 .

The nomenclature of Aeshna brevistyla caledonica requires some consideration. The species is predominantly reported in the contemporary literature under the genus Adversaeschna . This name was proposed by Watson (1992) who analysed the species’ affinities and suggested a subgeneric status within Aeshna . The name was subsequently given a full generic status without further justification and is used to denote not only the New Caledonian populations of A. brevistyla (probably due to Davies (2002) who used it for the first time), but also Australian ones. Given the lack of published evidence to justify the elevation of this name to genus rank, we treat Adversaeschna as a subgenus, as proposed by Watson (1992) for Aeshna brevistyla ( Table 1 ).

Distribution ( Fig. 40 ). A New Caledonian endemic subspecies, belonging to a monotypic subgenus that occurs elsewhere in Australia, New Zealand, Norfolk Islands, Raul Island in the Kermadec Archipelago, and Vanuatu ( Lieftinck 1975). The subspecies A. brevistyla caledonica is recorded from more than 20 localities in the Province Sud, with important populations in the Plaine des Lacs. One specimen collected at Anse Vata in Nouméa is in the ONNC collection.

Habitat. This species reproduces in sunlit standing waters, including swamps, ponds, lakes and sometimes still parts of streams and rivers in open areas. Typical habitats support sparse reed growth. This subspecies seems to prefer ultramafic areas.

Biology and behaviour. Its larva was described by Lieftinck (1976). According to Rowe (1987), in New Zealand, eggs are between 1.3 and 1.5 mm long and the last larval stadium often emerges at night. The larvae climb to a height of 20–30 cm where adult emergence takes place. About three and a half hours later, the dragonfly flies off. In the Plaine des Lacs, exuviae were found on reeds, on low shrubs emerging from the water or high herbaceous clumps on banks. Males are territorial and tirelessly patrol the same path above the water while waiting for the arrival of a female. After mating, females lay their eggs alone in rushes and reeds emerging from the water.

Status. Aeshna brevistyla caledonica is only known from New Caledonia where it appears restricted to the Province Sud, but with large populations. We consider this species not at risk in the short term (NT).

Figures

FIGURE 39. Aeshna brevistyla caledonica, male.

FIGURE 40. Records of Aeshna brevistyla caledonica.