A part of Japanese species of the genus Thiotricha Meyrick, 1886 are reviewed. Three species described by Omelko (1984) in the genus Cnaphostola Meyrick, 1918 are placed in combination with Thiotricha; Thiotricha biformis, T. angustellacomb. nov. and T. venustaliscomb. nov. These species are redescribed, and two new species, T. elaeocarpiella Kyaw, Yagi & Hirowatari, sp. nov. and T. flavitermina Kyaw, Yagi & Hirowatari, sp. nov. are described based on external morphological characters of adults and genitalia of males and females. Thiotricha chujaensis (Park, 2016), comb. nov. described in Cnaphostola from Korea, is newly recorded in Japan feeding on Mallotus japonica (Euphorbiaceae). One of the new species, T. elaeocarpiellasp. nov. has been associated with two different plants, Elaeocarpus zollingeri (Elaeocarpaceae) and Rhaphiolepis indica (Rosaceae). This paper presents the first comprehensive description of the morphology, pupal morphology and biology of species previously treated in the genus Cnaphostola and their relatives in Japan.

The taxonomy and biology of the immature stages of two gelechiid species of Thiotricha Meyrick, 1886, found in the southeastern part of the Sino-Japanese region is presented. Thiotricha lumnitzeriella Kyaw, Ueda & Hirowatari sp. nov., from islands in southwestern Japan is described. The larva of this species feeds as a portable case maker on Lumnitzera racemosa Willd. (Combretaceae). Thiotricha gemmulans Meyrick, 1931 originally described from India is newly recorded from Japan, mainland China, and Thailand. This species feeds as a portable case maker on Glochidion zeylanicum var. lanceolatum (Hayata) and G. zeylanicum var. zeylanicum (Gaertn.) A. Juss (Phyllanthaceae). Thiotricha acrophantis Meyrick, 1936 is newly synonymized with T. gemmulans.                Images of the adults of Thiotricha lumnitzeriella sp. nov. and T. gemmulans including genitalia, and images and illustrations of the larval chaetotaxy and pupa for both species are provided. Larval feeding habits are described in detail.

The genus Palumbina Rondani, 1876 belongs to the family Gelechiidae, which was until recently believed to comprise 26 species worldwide and mainly occurring in the Oriental region. Previously, only P. pylartis (Meyrick, 1908) had been recorded from this genus in Japan. In this study, five other species were identified. Four species were recorded for the first time in Japan, and another was newly described: P. acerosa Lee & Li, 2018; P. grandiunca Lee & Li, 2018; P. macrodelta (Meyrick, 1918), P. operaria (Meyrick, 1918) and P. muraseae Kyaw & Yagi, sp. nov. The host plant and larval feeding habits of P. pylartis, P. acerosa, P. grandiunca, and P. muraseae Kyaw & Yagi, sp. nov. were revealed. The immature stages of P. grandiunca, P. pylartis, and P. muraseae Kyaw & Yagi, sp. nov., including larval and pupal morphology, were first documented for the genus in which the larval chaetotaxy of P. pylartis and P. grandiunca is well observed. In their larval chaetotaxy, the details of their interspecific variation in the relative position and length of some setae are described. The pupal morphology of the species examined in this study is almost identical to the genus Thiotricha except for different traits on the abdominal segments A7 and A10. The traits of larval chaetotaxy and pupal morphology are also discussed for the subfamily. Photographs of the adult, male and female genitalia, and information on their biology and immature stages are provided.