Eugoa tau Volynkin 2022, comb. n.
Creators: name: Volynkin, Anton V.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Lepidoptera
Erebidae
Eugoa
Eugoa tau

description: Eugoa tau (Heylaerts, 1891), comb. n.   
(Figs 4–6, 9, 11)  
 Aemene tau Heylaerts, 1891, Annales de la Société entomologique de Belgique, 35: ccccxiv (Type locality: “Préanger (Java)”).   
 Type material examined. Holotype (by monotypy) (Figs 4, 11): female, [Indonesia] “ Java. | Hellmeyer ” / “Museum Leiden. | S. tau | Det: Heyl.” / “Cat.№ | 1” / blue stripe- like label / blue label [gen. prep. No.] “JDH 16” / QR- code label with unique number “ RMNH.INS | 1148684” (RMNH).   
 Additional material examined. CAMBODIA: 1 male, Mondolkiri Prov., Seima Biodiversity Conservation Area, between Seima and O’Rang, 12°12'12''N 107°01'09''E, 300m, 30.I.200, G. Csorba & G. Ronkay leg., gen. prep. No.: ZSM Arct. 2019-141 (prepared by Volynkin) (MWM / ZSM); THAILAND: 1 male, 1 female, Chiang Mai, Chiang Dao, Doi Din Daeng, 525m, 19°19'26''N 98°55'26''E, 1.XII.2005, K. Černý leg., gen. prep. Nos.: AV4009 (male), AV4010 (female) (prepared by Volynkin) (CKC); INDIA: 1 female, W.B. [West Bengal] Darjeeling, Manjitar, 650m, 19.VII.1989, Dr. W. Thomas leg., gen. prep. No.: ZSM Arct. 2019-110 (prepared by Volynkin) (MWM / ZSM).   
 Diagnosis. The forewing length is 7.0–8.0 mm in males and 7.0–9.0 mm in females. The species (Figs 4–6) is externally reminiscent of Eugoa cucullata (illustrated by Holloway (2001) and Bucsek (2012)) but differs in the T-shaped discal spot of the forewing, which is narrowly elliptical in the congener. Despite the external similarity, the male genital capsule of E. tau (Fig. 9) differs greatly from E. cucullata (illustrated by Holloway (2001) and Bucsek (2012)) in the proximally broader valva with the markedly shorter and distally dilated and apically bilobate cucullus (it is nearly elliptical in the congener). The male genital capsule of the current species is most similar to the externally dissimilar E. cernyi (Figs 3, 10) but distinguished by the more upcurved valva, the narrower and more prominent dorsal tip of the cucullus, and the markedly narrower and sparser setose cluster on the inner surface of the cucullus. The phallus of E. tau is narrower than in E. cucullata and has a long and heavily sclerotised dorsal carina bearing a robust thorn-like apical process directed dorsally and two additional denticles positioned more proximally whereas in the congener, the carina is shorter and weakly serrulate. Compared to E. cernyi, the phallus of E. tau is proximally narrower and has a sclerotised and armed carina. The vesica of the current species is proximally narrower than in E. cernyi, and the distal diverticulum is sack-like dilated whereas it is gradually distally tapered in the congener. The female genitalia of E. tau (Fig. 11) differ clearly from E. cucullata (illustrated by Holloway (2001) and Bucsek (2012)) in the narrower antevaginal plate with a deep medial incision, the broad, asymmetrical and heavily sclerotised ductus bursae (it is narrow and membranous in the congener), and the larger, sack-like corpus bursae, which is globular in E. cucullata. Compared to E. cernyi (Fig. 12), the female genitalia of E. tau have a narrower, trapezoidal antevaginal plate with a medial incision whereas it is pentagonal with lateral and postero-lateral narrowly triangular processes in the congener. The ductus bursae of E. tau is shorter and broader than in E. cernyi and has an anterior-lateral semicircular pocket whereas that of E. cernyi is symmetrical and gradually tapering anteriorly. The corpus bursae of E. tau is sack-like and evenly covered with minute spinulose scobination whereas in E. cernyi, it has a posteriorlateral semiglobular dilation bearing more robust spinulose scobination.   
 Distribution. The species is widespread from Java through Indochina to India and Sri Lanka (Hampson 1900; Černý & Pinratana 2009; Bae et al. 2016).
description: Published as part of Volynkin, Anton V., 2022, On the taxonomy of the genus Eugoa Walker (Lepidoptera: Erebidae: Arctiinae) with a description of a new species from the Andaman Islands (India), pp. 36-42 in Ecologica Montenegrina 60 on pages 40-41, DOI: 10.37828/em.2022.60.6, http://zenodo.org/record/13240044