Simulium (Nevermannia) maeaiense Takaoka & Srisuka, 2011: 57 –70 (Female, male, pupa and larva).
Specimens examined. One female and one male, reared from pupae collected from a small stream (width 20 cm, depth 2 cm, bottom rocky, water temperature 7.0˚C, partially shaded, elevation 1,893 m, 22˚21’28.378”N/ 103˚45’52.084”E) slowly flowing in shrubs, Lai Chau, Sapa, Lao Cai Province, northern Vietnam, 20-XII-2014, by H. Takaoka, M. Sofian-Azirun, Z. Ya’cob, C.D. Chen & K.W. Lau.
Distribution. Thailand and Vietnam (Lao Cai) (New record).
Remarks. Simulium (N.) maeaiense was described from Thailand (Takaoka and Srisuka 2011). This is the first record of this species from Vietnam. This species is characterized by the female genital fork with a sclerotized horizontal bar at the base of the anterodorsal projection on each lateral arm, male upper-eye facets in 19 vertical columns and 20 horizontal rows, paramere with five or six hooks, pupal gill with six long filaments arranged horizontally as 2+1+2+1 from inside to outside, and cocoon with an elongate anterodorsal projection (Takaoka and Srisuka 2011). There are differences in several morphological features between Vietnamese and Thai specimens (characters of Thai specimens in parentheses): in the female, body length 3.2 mm (2.4–2.6 mm), wing length 3.1 mm (2.6–2.8 mm), cibarium with 33 processes (40–44 processes), fore basitarsus 8.5 times as long as its greatest width (8.4 times), hind basitarsus 7.6 times as long as its width (6.2–6.8 times), 0.7 times as wide as the hind tibia (0.8 times), 0.6 times as wide as the hind femur (0.6–0.7 times), claw with a large basal tooth 0.46 times as long as the claw (0.49 times), spermatheca ovoidal and 1.3 times as long as its width (1.2 times); in the male, body length 3.0 mm (2.6–2.9 mm), wing length 2.9 mm (2.4–2.5 mm), scutum brownish black to black with no longitudinal vittae (dark brown with three longitudinal vittae), subcosta with three to five hairs (without hairs), hind basitarsus 4.4 times as long as wide (4.6–4.9 times), 1.0 times as wide as the hind tibia (0.9 times), 1.1 times as wide as the hind femur (0.9 times).