Two new chironomids bearing peculiar morphological features from Japan and China (Diptera: Chironomidae)

Abstract

A new subgenus, Nothorthocladius, of the genus Orthocladius v. d. Wulp and a new genus Yaethauma which bears a superficially resemblance to Collartomyia Goethgebuer of the subfamily Chironominae are erected, and the subgeneric and generic diagnoses are provided here. Orthocladius (Nothorthocladius) brevistylus sp. n. is described based on a single male and Yaethauma longiligulata sp. n. is described in both sexes. The former species is characterized from any other orthoclads by having the short gonostylus fused to gonocoxite. The species is treated as a member belonging to the genus Orthocladius based on various morphological features. The latter species is distinguishable from two other members of Collartomyia species by having the antepronotal lobe distinctly narrowed dorsally, the long ligula being sclerotized on the dorsolateral surface along outer margin, and the distinctly bifurcated pulvilli. Furthermore, in the male, the long and spindle-shaped anal point, the short and ovoid gonostylus, the long and distally expanded median appendage, the short and dorsolaterally elongate laterosternite, the plate-like apodeme lobe and the spermatheca bearing sclerotized neck in the female will be sufficiently separated from any described genera clearly.