Morphological and molecular evidence for a new species of Lutzia (Diptera Culicidae: Culicini) from Thailand

We found a species of Lutzia Theobald (1903) (Diptera: Culicidae) in Chiang Mai Province and other provinces in northern Thailand which bears morphological and DNA sequence differences from the three species of Lutzia, subgenus Metalutzia Tanaka, previously recorded from Thailand, namely Lt. fuscana (Wiedemann), Lt. halifaxii (Theobald) and Lt. vorax Edwards. The adults of the Chiang Mai form (CM form) have abdominal banding patterns similar to those of Lt. vorax from Japan (which includes the type locality of this species), but differ in having the mediocubital crossvein usually positioned before rather than beyond the radiomedial crossvein. The thoracic and abdominal integument of Lt. vorax larvae is covered with relatively short pointed spicules whereas it is covered by denser, longer and more acutely pointed spicules in the CM form. Some differences are also found in the development of thoracic seta 1-M, and abdominal setae 8-II and 8-III. The pupa of the CM form clearly differs from the pupa of Lt. vorax in having setae 1 and 5 of abdominal segments V and VI branched rather than single. The characters of the wing, larva and pupa of the CM form are similar to those of Lt. fuscana and Lt. halifaxii. However, whereas the phallosome of males of the CM form is similar to males of Lt. vorax and Lt. halifaxii, it is distinct from males of Lt. fuscana. Phylogenetic analysis of mitochondrial cytochrome c oxidase subunits I and II sequences revealed that the CM form falls outside a clade comprised of specimens of Lt. vorax from Japan, Korea, Thailand and Bhutan (Kimura 2-parameter, K2P, genetic distances 3.9–5.6, and 5.1–6.6, respectively). However, the two gene sequences of the CM form are not clearly distinct from clades comprised of sequences from specimens of Lt. fuscana and Lt. halifaxii (K2P 0.2–2.4%). However, based on the combination of morphological and molecular data, the current study provides evidence that the CM form is a previously unrecognized species of the genus Lutzia.