Agabus longissimus Régimbart

Brancucci, Michel & Hendrich, Lars, 2008, 5100 m above sea level: Agabus joachimschmidti sp. n. and notes on other high altitude diving beetles from Tibet and Bhutan (Coleoptera, Dytiscidae), Zootaxa 1825, pp. 51-58 : 54-55

Agabus longissimus Régimbart

Agabus longissimus Régimbart, 1899 : Régimbart (1899); Brancucci (1983); Nilsson (1995); Pederzani (2002).

Material studied. “ Bhutan, Thimpu Prov., Druk Path, marsh near Janye Tsoh, 4100 m, 10.12.2005, A. Bloch” (3 exs., NMW; 1 ex., NMB). “ China, SE Qinghai road Toramarkog-Nangqén, pass 20 km N NANGQÉN, alpine meadows, 4500 m, Rejsek leg., 25.6.1995 ” (2 exs., CLH).

Remarks. Agabus longissimus Régimbart was described in 1899 on the basis of two male specimens collected in 1897 at “Su-Tchuen” by local people. One of these was found in the collections of the Muséum National d’Histoire Naturelle, Paris, and was designated as lectotype ( Brancucci 1983). The second specimen mentioned in the original description is not present in the Paris Museum collections. In the same paper, Brancucci (1983) recorded this species from Gnatong (Sikkim) on the basis of a small series of specimens that were also found in the Paris Museum. Wu (1937) recorded this species from Mongolia, and Stastný (1996) reported it from oligotrophic pools in the subalpine and alpine zones of Sichuan and Qinghai. Later, Pederzani (2002) mentioned a further locality in Sichuan, SW of Kanding, leg. L. & R. Businský, 2001, at an altitude between 3200 and 4600 m.

The material recorded here and collected a century after the first known specimens shows that this species is apparently widespread but remains very rarely found. It occurs only at very high altitudes, between 3200 and 4600 m, as indicated on the labels of the known specimens.

This species undoubtedly belongs to the guttatus -group, characterized by a medial gap in the anterior row of punctures on pronotum ( Nilsson 1990). In its form it is very similar to A. biguttatus (Olivier) but is somewhat narrower. One striking characteristic is the coarse upper surface of the females, which seems to be constant and not accidental as it is in many other Agabus -species. For further details, refer to the original description ( Régimbart 1899) and to Brancucci (1983).

Distribution. China (Sichuan, Quinghai), Bhutan and India (Sikkim), between 3200–4600 m.