Redescription and commentary on the Chinese mayfly Vietnamella sinensis (Ephemeroptera: Vietnamellidae)

Abstract

The genus Vietnamella Tshernova, 1972 is reviewed and 3 valid species are confirmed. They are V. ornata (Tshernova, 1972), V. sinensis (Hsu, 1936) Tshernova, 1972. The nymphal and key imaginal characters of V. sinensis are described and figured. The monogeneric family Vietnamellidae has long series of autapomorphies (two pairs of projections on head, modified mandibles, slender maxillae with few setae, round hindwings, and half of egg covered with single cap) and some plesiomorphies (seven pairs of gills, large hindwings, few marginal intercalaries on forewings). The structures of mouthparts, head and forefemora suggest that nymphs of Vietnamella may be able to move substrates and scrape food from them. Morphological evidences show that the family Vietnamellidae is a basal clade of Ephemerelloidea.

Vietnamellidae (Insecta, Ephemeroptera) of Thailand

“…1 (Tang et al 2014), Vietnamella sp. A (Selvakumar et al 2018) and V. thani (Hu et al 2017 and unpublished data). now considered as a junior synonym of V. sinensis (Hu et al 2017) and this sequence likely refers to this species.…”

“…C from the BOLD system. Outside of Thailand distribution of Vietnamella is based on previous records including V. ornata (Tshernova, 1972), V. sinensis (Hu et al 2017), Vietnamella sp. 1 (Tang et al 2014), Vietnamella sp.…”

“…The monogeneric family Vietnamellidae was originally established by Tshernova (1972) [type species: Vietnamella thani Tshernova, 1972] based on larval specimens. The status of the family and the taxonomic history of the genus Vietnamella Tsher-nova, 1972 are reviewed by Jacobus et al (2005) and Hu et al (2017) respectively. Nowadays, three species have been described from the Oriental region.…”

“…They are V. ornata (Tshernova, 1972), V. sinensis (Hsu, 1936) [=V. dabieshanensis You & Su, 1987, V. qingyuanensis Zhou & Su, 1995, V. guadunensis Zhou & Su, 1995, and V. thani (Hu et al 2017). The larval and imaginal stages of V. sinensis have been described, whereas V. thani is only known from the larval stage and V. ornata (Tshernova, 1972) only from the sub-imaginal stage.…”

“…The genus Vietnamella is endemic in the Oriental region and is distributed in China, Thailand, India and Vietnam (Tshernova 1972;Jacobus et al 2005;Hu et al 2017;Selvakumar et al 2018). In Thailand, Vietnamella has never been reported at the species level.…”