Rediscovery of the mysterious Taiwanese micromoth Pachyrhabda citrinacma Meyrick, 1936 (Stathmopodidae) in museum and field, with notes on the fern-spore feeding larva Author Shen, Zong-Yu Biodiversity Research Center, Academic Sinica, Taipei, Taiwan. & Department of Life Science, National Taiwan Normal University, Taipei, Taiwan. Author Su, Hung-En Department of Entomology, National Taiwan University, Taipei, Taiwan. Author Hsu, Yu-Feng 0000-0003-2091-7775 Department of Life Science, National Taiwan Normal University, Taipei, Taiwan. t43018@ntnu.edu.tw text Zootaxa 2024 2024-04-30 5446 2 288 294 http://dx.doi.org/10.11646/zootaxa.5446.2.11 journal article 10.11646/zootaxa.5446.2.11 1175-5326 11101508 EF30C015-1BF3-4667-9C04-BDABB2B74113 Pachyrhabda citrinacma Meyrick, 1936 Figure 1–3 Pachyrhabda citrinacma Meyrick, 1936: 617 . Type locality: “Taihoku, Formosa ”. Material examined Syuti Issiki-collected specimen: The specimen of Pachyrhabda citrinacma retrieved in ( NTUE ) . 1 ♂ , Taiwan : “ ♂ . Taiwan , Sinten [=Xindian], 17 Apr 1935 , S. Issiki Coll. ( 1♂ , Gen. Prep. ZYS-0252, NTUE ). ( Fig. 1 ; Fig. 3A–B ) . Additional material examined. 3♀ , Taiwan : New Taipei City , Xindian , Sikanshui , ca 500m , 12 Feb 2018 , reared from Asplenium nidus , emg. 24 Mar–1 Apr 2018 , Z. Y. Shen Coll. ( NTNU ) . 1♂ , 1♀ , Taiwan : Yilan , Datong , Qilanshan , ca. 420m , 25 Mar 2018 , reared from Aglaomorpha coronans , emg. 15 Apr–1 May 2018 , Z. Y. Shen FIGURE 1. Issiki collected specimen of Pachyrhabda citrinacma Meyrick, 1936 . Specimen of Pachyrhabda citrinacma from NTUE, TAIWAN: New Taipei City, Xindian. Scale bar = 1 mm. FIGURE 2. Adults of Pachyrhabda citrinacma Meyrick, 1936 . A, B: Male specimen, TAIWAN: Kaohsiung, Taoyuan, Fenggangshan. C, D: Female specimen, TAIWAN: Kaohsiung, Taoyuan, Fenggangshan. Scale bars: A, B, C, D = 5 mm. FIGURE 3. Genitalia of Pachyrhabda citrinacma Meyrick, 1936 . A, B: Male genitalia of Issiki-collected specimen. C, D: Male genitalia, TAIWAN: New Taipei City, Wulai, Fushan (Gen. Prep. ZYS-0083, NTNU). E: Female genitalia, TAIWAN: New Taipei City, Wulai, Fushan (Gen. Prep. ZYS-0204, NTNU). Scale bars: A, B, C, D, E = 0.5 mm. Coll. ( NMNS ) . 1♀ , Taiwan : Tainan , Dongshan , Kantoushan , ca. 600 m , 4 Jul 2018 , reared from Asplenium nidus , emg. 29 Jul 2018 , Y. F. Hsu Coll. ( NTNU ) . 1♂ , Taiwan : Taizhong , Heping , Shaolai , ca. 800m , 30 Sep 2018 , reared from Neolepisorus fortunei , emg. 1 Oct 2018 , Y. Y. Lu Coll. ( NMNS ) . 3♂ , 2♀ , Taiwan : New Taipei City , Wulai , Fushan , ca. 800m , 7 Jan 2019 , reared from Antrophyum formosanum , emg. 10–23 Feb 2019 , Y. F. Hsu Coll. ( 1♂ , Gen. Prep. ZYS-0083, NTNU ) . 1♂ , 13♀ , Taiwan : New Taipei City , Wulai , Fushan , ca. 800m , 11 Feb 2020 , reared from Antrophyum formosanum , emg. 11–28 Mar 2020 , Y. F. Hsu Coll. ( 1♀ , Gen. Prep. ZYS-0204, NTNU ) . 2♂ , 1♀ , Taiwan : Kaohsiung , Taoyuan , Fenggangshan , ca 1000m , 20 May 2020 , reared from Asplenium antiquum ,emg. 27 Jul–19 Aug 2020 , Z. Y. Shen , J. Y. Liang Coll. ( NTNU ) . Redescription. Male ( Fig. 2A–B ): Forewing length 2.7–3.5 mm (n=3). Head: frons white, vertex covered by whitish-ocherous scales, occiput ocher; antenna with scape rod-shaped, white with black scales at the connection of flagellum, flagellum white; labial palps slender, long, strongly upcurved, white. Thorax: ocher with whitish streak on the anterior and posterior margin respectively. Legs: white; ventral side of fore legs covered by scales; mesotibia bearing a pair of spurs at distal joint, with outer spur approximately 1/2 length of inner spur; hind legs with black scales overlaid at junction of tibia and tarsus; metatibia overlaid with whitish bristles; metatibia bearing two pairs of whitish spurs at both proximal and distal joints, proximal spurs with outer one approximately 1/3 length of inner one, distal spurs with outer one approximately same length as inner one; metatarsus bearing a whorl of whitish bristles on each tarsomere. Forewing: ground color white with two ocherous blotches, widest toward costa, one located at -base and the other at middle of wing; cilia white. Hindwing: ground color white; cilia white. Abdomen bright orange-ocher; anal tuft present. Female ( Fig. 2C–D ): Forewing length 3.3–3.4 mm (n=3). Similar to male but lacking anal tuft in abdomen. Male genitalia ( Fig. 3C–D ): Uncus elongated triangular, apically down-curved, with acute apex, setae present laterally; gnathos tongue-shaped, approximately same length as uncus; tegumen well-developed; valva nearly oblong; costa acute at base; sacculus acute at base; costa nearly as thick as sacculus; cucullus oval, nearly same length as uncus, with numerous setae on inner surface; saccus nearly the same length as uncus; anellar lobes oval with numerous setae; phallus stout, approximately 3x as long as uncus, basal sclerotized structure developed, acute triangular, cornutus absent. Female genitalia ( Fig. 3E ): Papillae anales longer than width; apophyses posteriores slightly longer than apophyses anteriores; ostium bursae funnel-shaped; ductus bursae shorter than corpus bursae, corpus bursae with horn-shaped signum, situated at about anterior 1/3 of corpus bursae; bulla round; ductus seminalis with many small spines present at proximal end. Diagnosis. This species is superficially similar to Pachyrhabda antinoma Meyrick, 1910 and P . inanis Meyrick, 1936 . However, it can be distinguished from these two species by the distinctive color of its thorax. While the thorax of P . citrinacma exhibits an ocherous coloration, the thorax of P . antinoma and P . inanis is characterized by a whitish coloration. Host plants. Asplenium antiquum Makino, 1929 , A . nidus L., 1753 ( Aspleniaceae ), Aglaomorpha coronans (Wall. Ex Mett.) Coppel., 1929 , Neolepisorus fortunei (T. Moore) L. Wang ( Polypodiaceae ), and Antrophyum formosana Heron., 1915 ( Pteridaceae ). Biology. Larvae have been collected nearly the whole year in Taiwan . They constructed roughly oval shelters on the underside of the host fern fronds, adorned with silk, fern spores and their own frass ( Fig. 4A ). The larva ( Fig. 4B ) lived inside the shelter and fed on the spores until pupation. The pupae, which were oval-shaped, were enclosed within loose cocoons situated within the larval shelters ( Fig. 4C ). About one to one and a half month after pupation, adult moths ( Fig. 4D ) emerged without undergoing diapause. Distribution. Taiwan .