Contribution to Knowledge of the Oriental Taxa of the Diduga (Lepidoptera: Erebidae: Arctiinae)

Abstract

The type material of Diduga costata Moore, [1887], D. flavicostata (Snellen, 1879), D. fulvicosta Hampson, 1891, D. barlowi Holloway, 2001, and D. zetes Bucsek, 2014 are presented. Three new species are described based on the genitalia of type specimens from Indonesia (Sulawesi) and Laos. Three new combinations and one new synonym are established. An updated checklist of known species of the genus are presented with information of depositors and distributions. Illustrations of the adults and genitalia of the type materials and examined species are provided.

1. Introduction

Erebidae is one of the taxonomically more diverse families of the superfamily Noctuoidea, with a global total of 24,500 described species of about 1750 genera in 18 subfamilies [1,2]. The synapomorphy of the subfamily Arctiinae is a prespiracular countertympanal hood (earlike structure) [2]. Locations of the tympanal ears of insects are different for each group: on the thorax (Noctuoidea, Corixidae, etc.), abdomen (Pyraloidea, Geometroidea, Drepanoidea, Cicadoidea, etc.), wings (Hedyloidea, Papilionoidea, Chrysopidae, etc.), forelegs (Grylloidea, Tettigonioidea, etc.), mouth-parts (Bombycoidea), antenna (Culicoidea, Tephritidae, Corbiculata-Apis), etc. The presence of a pair of dorsal pheromone glands of females [3,4,5] and vein Sc of the hindwing, which tends to be swollen basally in both sexes [3], are the best synapomorphic characters of this subfamily.

The genus Diduga Moore, [1887] (in 1884–1887) is one of the smaller genera within the tribe Lithosiini (Arctiinae). It was erected for its type species, Diduga costata Moore, 1887 from Sri Lanka. Until the early 2000s, the type species of Diduga was designated as Pitane flavicostata Snellen following Hampson’s catalogue [6]. Holloway [7] characterized the adults and genitalia of this genus and redesignated D. costata Moore as the type species of this genus without illustrations of the two candidate species. Meanwhile, Fang [8] recorded D. flavicostata from China as the type species as D. costata.

Recently, Zhao & Han [9] listed this genus with the inclusion of 43 species, but the species Utriculoferiana macroplaga (Hampson, 1900) was erroneously included in the present genus. One new species, D. weiweii Zhao, Wu & Han, 2020, has been described by Zhao et al. [10] from Malaysia; one new species, D. sphaeracephalus Bayarsaikhan & Bae, 2020 by Bayarsaikhan et al. [11] from Thailand; two new species, D. hastata Bayarsaikhan & Bae, 2021 and D. mucronata Bayarsaikhan & Bae, 2021 by Bayarsaikhan et al. [12] from Laos; and one new species, D. nantouensis Bayarsaikhan & Bae, 2021 by Bayarsaikhan et al. [13] from Taiwan. To date, 47 described species are known in the genus Diduga in the world.

At this time, a new synonym, D. zetes syn. nov. for D. barlowi Holloway and three new combinations, Tospitis metaleuca (Hampson), comb. nov., T. amoenusa (Bucsek), comb. nov., and T. ambigua (Bucsek), comb. nov. to the genus Tospitis Walker, 1863, are proposed. Additionally, three new species, two from Indonesia (northern Sulawesi) and one from Laos (Bolikhamsai province), are described based on the genitalia of the type species D. costata and D. flavicostata.

2. Materials and Methods

The present study was based on the collections of Incheon National University (Incheon, Republic of Korea) and McGuire Center for Lepidopteran and Biodiversity, Florida Museum of Natural History (Gainesville, FL, USA). All types of the D. robdevosi sp. nov. are deposited in the INU, and D. minahasa sp. nov. and D. dumoga sp. nov. are in the MGCL. Figures of the holotypes and syntypes of the species D. costata, D. flavicostata, D. fulvicosta, D. barlowi, D. zetes, D. metaleuca, D. amoenusa, and T. ambigua are based on material from collections of Museum WITT München (München, Germany), the Natural History Museum (London, UK), and the Naturalis Biodiversity Center (Leiden, The Netherlands).

3. Results

3.1. Systematic Accounts of the Genus Diduga Moore, [1887]

Diduga Moore [14]: 535. TS: Diduga costata Moore, [1887].

Androstigma Hampson [15]: 13, 82. TS: Diduga albicosta Hampson, 1891.

• Note. Diduga was recently characterized by Holloway [7].

3.2. The Species of Diduga

3.2.1. Diduga costata Moore [1887]

Diduga costata Moore [14]: 535. TL: Sri Lanka (Dickoya).

Type material examined. Holotype of Diduga costata: male (Figure 1a), “Ceylon|♂|Green|12”/“Diduga costata ♂|Type. Moore”/red ring “Type” label/“Moore Coll.|94–106.”/QR-code label with a unique number: “NHMUK010598569” (prepared by Volynkin) (NHMUK).

Redescription. Adult (Figure 1a). Wingspan 16 mm in the male. Head and patagium deep yellow. Thorax dark brown. Ground color of narrow triangular forewing dark brown, with broad, deep yellow costal and terminal border. Costal margin with two dark brown, irregularly triangular patches in antemedial and postmedial lines edged by a narrow dark line from basal to antemedial patch. Cilia deep yellow. Hindwing pale brown. Cilia pale brown. Abdomen pale brown. Male genitalia (Figure 2a). Uncus irregularly conic, with hook-shaped apical process, heavily covered with long setae. Tegumen triangular, weakly sclerotized. Symmetric valvae stout, with a long, slender, waved, spine-shaped projection in the upper angle and a stout, short (half-length of upper one), waved, finger-shaped projection in the lower angle; costal area broadly rounded, with sclerotized margin; and sacculus blunted, roundly angled, with stronlgy sclerotized margin and membranous sacculus process elongated, almost the same length with an upper angle’s projection. Juxta weakly sclerotized, elongated, arch-shaped. Vinculum strongly sclerotized, short (one-third length of tegumen), saccus rectangular. Aedeagus (broken in the slide) and vesica covered with short, thin spines and a bundle of large (3–4 times longer than thin spines) spines consisting of nine same-sized spines. Male pregenital plate (Figure 2b). Abdomen with median apodeme structure of lyrelike shape on pregenital tergite and directed anteriorly as twin thin arms with slightly recurved apices. Female genitalia (Figure 3a). Papillae anales weakly covered with setae. Antevaginal plate broadly U-shaped, weakly sclerotized. Ductus bursae tubular, membranous, with a large sclerotized rounded plate. Bulla membranous, broadly tubular. Ovoid corpus bursae membranous, without signum. Female pregenital plate (Figure 3b). The female pregenital sternite, laterally on each side to a sclerotized pouch on the intersegmental membrane.

Distribution. India [16], Sri Lanka [14].

3.2.2. Diduga flavicostata (Snellen, 1879)

Pitane flavicostata Snellen [17]: 92. TL: Indonesia (Makassar).

Diduga fulvicosta Hampson [18]: 52. TL: India (Nilgiris).

Diduga flavicostata: Hampson [6]: 541.

Diduga costata: Hampson [6]: 541.

Type material examined. Syntypes: two males (Figure 1c), Indonesia, Makassar, Cat. No. 12, RMNH.INS.1098990 and Cat. No. 13, RMNH.INS.1098991; one female (Figure 1d), Indonesia Bonthain, Cat. No. 11, RMNH.INS.1098992; two females, Indonesia, Takalar, Cat. No. 14, RMNH.INS.1098993 and Cat. No. 15, RMNH.INS.1098994. Holotype of Diduga fulvicosta: female (Figure 1b), “NILGIRIS.|Hampson Coll.|89–129.”/“296.|A.”/“Diduga fulvicosta.|-Hampson.|type ♀”/red ring “Type” label/QR-code label with a unique number: “NHMUK010598570” (NHMUK).

Redescription. Adult (Figure 1b–d). Wingspan 10 mm in male, 11 mm in female. Head and patagium light yellow. Thorax dark brown. Ground color of broadly triangular forewing dark brown, with broad, deep yellow costal and terminal border. Costal area with several small dark brown dots or absent, and costal margin more deep yellow, edged by a narrow dark line in the basal area. Cilia light yellow. Hindwing pale brown. Cilia pale brown. Abdomen pale brown, with pale yellow anal tuft in both sexes. Male genitalia (Figure 2c). Uncus irregularly conic, with a hook-shaped apical process, heavily covered with long setae. Tegumen triangular, weakly sclerotized. Symmetric valvae elongated, with a spine-shaped apex; costal area broadly rounded and sclerotized; sacculus sclerotized, and rounded saccular process membranous, shorter than apex of valva. Juxta weakly sclerotized, irregularly arch-shaped. Vinculum sclerotized, short, and saccus rounded. Aedeagus stout and vesica with a large spine and an elongated sclerotized plate. Male pregenital plate. Not provided. Female genitalia (Figure 3c). Papillae anales weakly covered with setae. Ductus bursae broadly tubular, weakly sclerotized. Ovoid corpus bursae membranous, with a large and sharply flexed band, covered with diverse-sized spines. Female pregenital plate. Not provided.

Distribution. India [19,20], China [8], Thailand [21], Cambodia and Malaysia [22], and Indonesia (Sulawesi, Java) [17, present paper].

Remarks. The adults and male genitalia of D. flavicostata were first illustrated by Bucsek [22], but after checking the syntypes of this species, it was found to belong to a new species. Indeed, all reports of D. flavicostata from the countries mentioned earlier may need further confirmation.

3.2.3. Diduga minahasa Bayarsaikhan, Heppner and Bae, sp. nov.

Type materials. Holotype ♂, Indonesia, Sulawesi, Dumoga-Bone National Park, 11–15 October 1985 (JBH), adult no. ARCT14578M and gen. slide no. JBH–3935, deposited in MGCL. Paratype (one female) INDONESIA: same data as holotype, adult no. ARCT14579F and gen. slide no. JBH–3936, deposited in MGCL.

Diagnosis. The wing pattern of this species is hardly distinguishable from many others of the genus Diduga. The male genitalia structure of the new species is similar to D. ciliata Holloway, 2001, but can be distinguished from the latter by the costal processes being symmetric, strongly flexed, with dilated apex and the left saccular process broader than the right; both processes are heavily covered with setae. In D. ciliata, the costal processes are asymmetric; the left one is tongue-shaped and the right one is hammer-headed, and the left saccular process is narrower than the right, not covered with setae [7].

In the female genitalia, membranous corpus bursae ovoid and wrinkled, with dentate and strongly sclerotized bands, cover the whole of bursae, separating this species well from all the other known Diduga.

Description. Adult (Figure 4a,b). Wingspan 11.5 mm in male (n = 1), 10.5 mm in female (n = 1). Head and patagium light yellow. Thorax dark brown. Ground color of broadly and roundly triangular forewing dark brown, with broad, deep yellow costal and terminal border. Costal area with two dark brown, triangular patches in antemedial (almost two times larger than postmedial patch) and postmedial lines and a row of small, dark dots or patches from basal of costa to tornus, edged by a narrow dark line in the basal area. Cilia deep yellow. Hindwing dark brown. Cilia dark brown. Abdomen dark brown, with pale yellow anal tuft in the male and dark brown in the female. Male genitalia (Figure 5a). Uncus slender, with small apical spine, heavily covered with setae. Tegumen triangular, weakly sclerotized, shorter than uncus. Asymmetric valvae with two symmetric basal costal processes, weakly sclerotized and strongly curved with a dilated apex; stout right valva weakly sclerotized, with a pointed apex, sacculus weakly sclerotized, and saccular process with a bundle of strong setae; apex of broader left valva heavily covered with strong setae. Juxta weakly sclerotized and plate-shaped. Vinculum strongly sclerotized, short (almost same size with tegumen), and saccus rectangular. Aedeagus slender, two times strongly angled, with rounded coecum, and vesica with a long, slender spine-shaped cornutus and an ovoid, sclerotized plate near apical cornutus. Male pregenital plate (Figure 6a). Abdomen with median apodeme structure of lyrelike shape on pregenital tergite. Female genitalia (Figure 7a). Papillae anales weakly covered with setae. Antrum rounded, with sclerotized ring. Ductus bursae broadly tubular, weakly scobinated partially. Corpus bursae globose, membranous, with dentate, strongly sclerotized bands that wholly cover bursae. Female pregenital plate. The female abdomen has no pregenital structure.

Distribution. Indonesia (northern Sulawesi).

Etymology. Named after the name of northern Sulawesi, Minahasa, Indonesia.

3.2.4. Diduga dumoga Bayarsaikhan, Heppner and Bae, sp. nov.

Type materials. Holotype ♂, Indonesia, Sulawesi, Dumoga-Bone National Park, 6–10 October 1985 (JBH), adult no. ARCT15430M and gen. slide no. JBH–3942, deposited in MGCL. Paratypes (one male, one female) INDONESIA: 1♂, Sulawesi, Dumoga-Bone National Park, 6–10 October 1985 (JBH), gen. slide no. JBH–3958; 1♀, Dumoga-Bone National Park, 11–15 October 1985 (JBH), adult no. ARCT15431F and gen. slide no. JBH–3957, deposited in MGCL.

Diagnosis. The male genitalia structure of the new species is similar to D. minahasa sp. nov., but can be distinguished from the latter by the asymmetric costal processes being half the length of tegumen, and the aedeagus is S-shaped with a subapical sclerotized plate covered by spines and a pointed coecum, and vesica with two large, irregularly shaped cornuti in male genitalia. In female genitalia, a broadly tube-shaped corpus bursae sclerotized the whole length and membranous ductus bursae obryriform, with a large, dentate, strongly sclerotized band from the cervix to the proximal end of bursae.

Description. Adult (Figure 4c,d). Wingspan 12 mm in male (n = 2), 11.3 mm in female (n = 1). Head and patagium pale yellow. Thorax dark brown. Ground color of braodly and roundly triangular forewing dark brown, with broad, pale yellow costal and terminal border. Costal area with 2–3 dark brown patches in subbasal (on the costal margin), antemedial (indistinct line, consist of brown scales) and postmedial lines edged by a narrow dark line in the basal area. Cilia pale yellow. Hindwing dark brown. Cilia dark brown. Abdomen dark brown. Male genitalia (Figure 5b). Uncus slender, with small apical spine, heavily covered with setae. Tegumen triangular, weakly sclerotized, almost same size with uncus. Asymmetric valvae with two strongly sclerotized, short, asymmetric costal processes with bifurcated apex; apex of valvae with two asymmetric, almost same-sized processes, upper one weakly elongated and rounded apex (more curved in left valva,) and stout, strongly sclerotized lower one covered with setae and with acute apex (rounded and crenated in left valva); and sacculus weakly sclerotized. Juxta ringed by narrow, sclerotized band. Vinculum weakly sclerotized, short (almost same size as tegumen), saccus rounded. Aedeagus slender, S-shaped, weakly sclerotized, with a subapical band-shaped plate covered by slender spines and pointed coecum, and vesica with two irregular shaped cornuti and weakly coverd by spiniculum. Male pregenital plate (Figure 6b). Abdomen with median apodeme structure of lyrelike shape on pregenital tergite. Female genitalia (Figure 7b). Papillae anales weakly covered with setae. Antrum rounded, strongly sclerotized wholly. Ductus bursae broadly tubular, sclerotized whole of length. Corpus bursae obryriform, and membranous, with a large, elongated, dentate, strongly sclerotized band from cervix to proximal end of bursae. Female pregenital plate. The female abdomen has no pregenital structure.

Distribution. Indonesia (northern Sulawesi).

Etymology. Named after the type-locality, Dumoga-Bone National Park, Sulawesi, Indonesia.

3.2.5. Diduga robdevosi Bayarsaikhan and Bae, sp. nov.

Type materials. Holotype ♂, Bolikhamsai Prov., Tad Leuk Waterfall (N 18°23′42.81″, E 103°04′18.70″ Alt: 206 m), 10 November 2015 (YS Bae, BS Park, SM Na, JW Kim, DJ Lee), adult and gen. slide no. INU–1905L, deposited in INU. Paratypes (11 males 2 females) LAOS: 1♂, Bolikhamsai Prov., Tad Xai Waterfall (N 18°27′05.98″, E 103°08′40.06″ Alt: 321 m), 8 November 2015 (YS Bae, BS Park, SM Na, JW Kim, DJ Lee), adult and gen. slide no. INU–1904L; 1♂, Bolikhamsai Prov., PKK Nat. Park (N 18°27′18.20″, E 103°03′17.60″ Alt: 465 m), 5 August 2016 (YS Bae, BS Park, SM Na, DJ Lee, JH Ko), adult and gen. slide no. INU–1968L; 1♂, Bolikhamsai Prov., PKK Nat. Park (N 18°27′23.76″, E 103°03′05.15″ Alt: 470 m), 22 July 2018 (YS Bae, DJ Lee, JH Ko, TG Lee, CM Jang, U Bayarsaikhan), adult and gen. slide no. INU–10061L; 3♂, Bolikhamsai Prov., PKK Nat. Park (N 18°25′11.75″, E 103°05′12.59″ Alt: 290 m), 29 August 2018 (YS Bae, SM Na, DJ Lee, JH Ko, TK Lee, YB Cha, CM Jang), gen. slide no. INU–10137L, 10125L, 10128L; 5♂, 2♀, Bolikhamsai Prov., PKK Nat. Park (N 18°25′11.75″, E 103°05′12.59″ Alt: 290 m), 3 September 2018 (YS Bae, SM Na, DJ Lee, JH Ko, TG Lee, CM Jang, CM Jang), adult and gen. slide no. INU–10143L, gen. slide no. INU–10145L, 10153L, 10147L, 10152L, 10144L (female), 10155L (female), deposited in INU.

Diagnosis. Diduga robdevosi sp. nov. has no remarkable external differences from a number of other members of the genus. However, in male genitalia, asymmetric valvae with a pair of different-sized, symmetric, rounded spur-shaped costal processes basally and apex of valvae with two and three diverse-sized processes (two in right, three in left), and aedeagus vesica with a long, slender spine-shaped cornutus and weakly scobinated; in female genitalia, irregularly triangular corpus bursae covered by diverse-sized short spines in distal half, and proximal half of bursae weakly wrinkled distinguishes this species well from all the other known Diduga.

Description. Adult (Figure 4e,f). Wingspan 11–11.5 mm in male (n = 13), 11.5 mm in female (n = 2). Head and patagium deep yellow. Thorax brown. Ground color of narrowly triangular forewing brown, with broad, deep yellow costal and terminal border. Costal area with two dark brown, irregularly triangular patches in antemedial and postmedial lines and a row of small, dark dots or patches from basal of costa to tornus; edged by a narrow dark line in the basal area. Cilia deep yellow. Hindwing pale brown. Cilia pale brown. Abdomen pale brown, with pale yellow anal tuft in the male and brown in the female. Male genitalia (Figure 5c,d). Uncus stout, curved apically, broadened medially, with a small apical spine, heavily covered with setae. Almost same length with tegumen. Tegumen triangular, weakly sclerotized. Asymmetric valvae with a pair of different sized, symmetric, rounded spur-shaped costal processes basally, weakly sclerotized; stout right valva weakly sclerotized, with a gap in the apex, upper, and lower processes pointed and different sized; apex of stout left valva with one large and two small apical processes; and saccular processes of both valvae rounded, membranous, and longer than apex of valva. Juxta weakly sclerotized, tubular. Vinculum sclerotized, almost same size with tegumen and saccus rectangular. Aedeagus stout, straight and with a short process in rounded coecum, and vesica with a long, slender spine-shaped cornutus, weakly scobinated. Male pregenital plate (Figure 6c). Abdomen with median apodeme structure of lyrelike shape on pregenital tergite and directed previously as twin broad arms. In segments 4–5 with two bundles of the strongly sclerotized and weakly waved spines. Female genitalia (Figure 7c). Papillae anales weakly covered with setae. Antrum rounded, U-shaped. Ductus bursae membranous, broad, short, with a strongly sclerotized plate, it is the same length with ductus bursae. Corpus bursae irregularly triangular, membranous, covered by diverse-sized short spines in distal half, and proximal half of bursae weakly wrinkled. Female pregenital plate (Figure 7d). The female pregenital sternite laterally on each side to a sclerotized pouch on the intersegmental membrane.

Distribution. Laos (Bolikhamsai province) and Malaysia [22].

Etymology. The species name is dedicated to Dr. Rob de Vos (Naturalis Biodiversity Center, Leiden, The Netherlands), the excellent entomologist (Lepidoptera) on Arctiinae of the Oriental region (Papua, Indonesia).

Remarks. This new species was previously reported in Malaysia by Bucsek [22] as D. flavicostata. However, based on the type specimen, we describe this as a new species herein.

3.3. The Checklist of Diduga Species in the World

A total of 47 Diduga species are listed herein, including three new species from Indonesia (Sulawesi) and Laos (Bolikhamsai province) (

Table 1. A synoptic list of the genus Diduga in the World, with depository of types and distributions.

	Species	Depositor	Distribution
1	Diduga albicosta Hampson, 1891	NHMUK	India, Sri Lanka, China, Laos, Thailand, Cambodia, peninsular Malaysia
2	Diduga albida Hampson, 1914	NHMUK	Dutch New Guinea
3	Diduga allodubatolovi Bayarsaikhan, Li & Bae, 2020	NKU	China, Laos, Thailand
4	Diduga alternota Bucsek, 2014	MWM	Laos, Thailand, Cambodia, Vietnam, Malaysia, Indonesia
5	Diduga annulata Hampson, 1900	NHMUK	Laos, Thailand, Cambodia, peninsular Malaysia, Indonesia (Borneo, Sumbawa)
6	Diduga barlowi Holloway, 2001 =Diduga zetes Bucsek, 2014, syn. nov.	NHMUK	Cambodia, Malaysia, Indonesia (Borneo)
7	Diduga bayartogtokhi Bayarsaikhan & Bae, 2019	INU	Vietnam
8	Diduga bispinosa Bayarsaikhan & Bae, 2018	INU	Thailand, Cambodia
9	Diduga chebalinga Zhao & Han, 2020	NEFU	China
10	Diduga chewi Zhao & Han, 2020	NEFU	Malaysia
11	Diduga ciliata Holloway, 2001	NHMUK	Indonesia (Borneo)
12	Diduga costata Moore, [1887]	NHMUK	India, Sri Lanka
13	Diduga cucphuonga Dubatolov & Bucsek, 2016	SZMN	Vietnam
14	Diduga dorsolobata Holloway, 2001	NHMUK	Indonesia (Borneo)
15	Diduga dubatolovi Bayarsaikhan & Bae, 2018	INU	Thailand, Cambodia
16	Diduga dumoga Bayarsaikhan, Heppner & Bae, sp. nov.	MGCL	Indonesia (northern Sulawesi)
17	Diduga excisa Hampson, 1918	NHMUK	the Philippines
18	Diduga flavicostata (Snellen, 1879)	RMNH	India, China, Thailand, Cambodia, Indonesia (Sulawesi, Java)
19	Diduga flavifinis Bucsek, 2014	MWM	Malaysia
20	Diduga fumipennis Hampson, 1891	NHMUK	India
21	Diduga haematomiformis van Eecke, 1920	RMNH	Indonesia (W. Java)
22	Diduga hainanensis Bayarsaikhan, Li & Bae, 2020	NKU	China
23	Diduga hanoiensis Bayarsaikhan & Bae, 2019	INU	Vietnam
24	Diduga hastata Bayarsaikhan & Bae, 2021	INU	Laos
25	Diduga hollowayi Zhao & Han, 2020	NEFU	Malaysia
26	Diduga iriomotensis Bae, Kishida & Bayarsaikhan, 2019	CYKJ	Japan
27	Diduga khounngeuna Bucsek, 2020	SNM	Laos
28	Diduga kohkongensis Bayarsaikhan & Bae, 2018	INU	Cambodia
29	Diduga luteogibbosa Bayarsaikhan, Li & Bae, 2020	NKU	Laos, China
30	Diduga minahasa Bayarsaikhan, Heppner & Bae, sp. nov.	MGCL	Indonesia (northern Sulawesi)
31	Diduga mininota Bucsek, 2014	MWM	Malaysia
32	Diduga mucronata Bayarsaikhan & Bae, 2021	INU	Laos
33	Diduga nantouensis Bayarsaikhan & Bae, 2021	INU	Taiwan
34	Diduga nigridentata Bayarsaikhan & Bae, 2019	INU	Vietnam
35	Diduga nota Bucsek, 2012	MWM	Malaysia
36	Diduga pectinifer Hampson, 1900	NHMUK	Indonesia (Borneo)
37	Diduga plumosa Hampson, 1911	NHMUK	Indonesia
38	Diduga quinquicornuta Bayarsaikhan & Bae, 2019	INU	Vietnam
39	Diduga robdevosi Bayarsaikhan & Bae, sp. nov.	INU	Laos, peninsular Malaysia
40	Diduga rufidisca Hampson, 1898	NHMUK	India
41	Diduga scalprata Bayarsaikhan, Li & Bae, 2020	NKU	Laos, China
42	Diduga simianshana Zhao & Han, 2020	NEFU	China
43	Diduga sphaeracephalus Bayarsaikhan & Bae, 2020	OPU	Thailand
44	Diduga spinosusa Bucsek, 2012	MWM	Malaysia
45	Diduga taiwana Bayarsaikhan & Bae, 2021	INU	Taiwan
46	Diduga trichophora Hampson, 1900	NHMUK	Myanmar, Thailand, peninsular Malaysia, Indonesia (Bali, Borneo, S. Burma, Sumatra, Java)
47	Diduga weiweii Zhao, Wu & Han, 2020	NEFU	Malaysia

). Based on an examination of the genitalia structures of the type specimens, D. zetes Bucsek [23] is synonym of D. barlowi Holloway [7] (Figure 8a–e) and D. metaleuca Hampson, D. amoenusa Bucsek, and D. ambigua Bucsek are transferred to the genus Tospitis Walker, 1863 (Figure 9 and Figure 10).

The genus Tospitis Walker, 1863 is one of the smaller genera within the tribe Lithosiini, comprising only 16 described species, which have been worked on by Walker [24], Hampson [25], Holloway [7], and Bucsek [22,23]. In this study, the examination of the genitalia structures of three species has led us to conclude that these species belong to the genus Tospitis Walker.

4. Discussion

In our study, we have listed a total of 47 Diduga species (Table 1), of which 38 (81%) have a typical wing pattern characterized by a dark brown ground color of the forewing with deep yellow costal and terminal bands. As a result, identification of these species must be based on genitalia structures, which can pose a challenge. For a century, the species D. flavicostata has been recorded in multiple countries, India, China, Taiwan, Thailand, Cambodia, and Malaysia, by different authors while the present type species, D. costata, was a junior synonym of D. flavicostata [8,11,16,22].

Members of this genus show much diversity of genitalia structure and it is probable that the genus is not monophyletic, caused typically by three kinds of valva shapes examined: simple and symmetric valvae have a needle-shaped apex, widened and asymmetric valvae are processed or branched/complicated, etc. Therefore, we suggest that the genus Diduga be subdivided into two or more distinct species groups or even different genera (slim chance). More evidence is needed and it should be deeply studied in the future.

Furthermore, it is also necessary to identify type specimens of some species that have not been recorded or collected for a long time at their type localities or in other countries, such as D. albida, D. excisa, D. fumipennis, D. plumosa, and D. rufidisca.