Thitarodes namnai Maczey

Maczey, Norbert, Dhendup, Kuenzang, Cannon, Paul, Hywel-Jones, Nigel & Rai, Tek Bahadur, 2010, Thitarodes namnai sp. nov. and T. caligophilus sp. nov. (Lepidoptera: Hepialidae), hosts of the economically important entomopathogenic fungus Ophiocordyceps sinensis in Bhutan, Zootaxa 2412, pp. 42-52 : 43-47

Thitarodes namnai Maczey , sp. nov.

Figs. 1–24

Etymology. The name refers to the location, where both holotype and paratypes were sampled, locally known as Namna.

Male. Description based on holotype ( Figs. 1–3 , 24 ).

SIZE: Wingspan: 37.5 mm; forewing length: 18.2 mm; hindwing length: 15.0 mm; body length: 14.8 mm. ANTENNAE: Rust brown with segments 4 to 9 dorsally darkened to blackish brown. BODY: Head and thorax blackish brown covered densely with rust coloured hairs turning ochraceous posteriorly; prothorax and mesothorax interspersed with dark brown hairs; abdomen brown covered in ochraceous yellow hairs.

FOREWINGS: Mainly rust coloured with extensive grey-white and black markings; narrow sub-terminal fascia grey-white extending from R3 to Cu2, interrupted between M2 and Cu2, basal accompanied by slightly wider, wavelike, black fascia extending basal towards centres of cells in places interrupted by rust coloured scales; reniform stigma, posterior half black with small grey-white discal spots, anterior half grey-white with black borders basal and distal; sub-basal patch of grey-white and black spots; large black spot filling cell between vein A and dorsum reaching distal 1/4 of wing; second large black spot filling cell between Cu2 and A in distal half; costa accompanied by series of small grey-white and black spots; fringe from R1 to Cu2 ochraceous yellow and blackish brown; dorsum edged grey-white. Costa straight; Sc unbranched; R2 and R3 stalked, length of stalk about 3/4 length from base of R2+3 to margin; R4 and R5 stalked, length of stalk about 1/ 6 of length from base R4+5 to margin; cross vein R5-M1 very weak but discernible, reaching R5 distad from furcation of R4 and R5; two cross veins between A and CuP; one crossvein between Cup and CuA; A reaching margin.

HINDWINGS: Uniformly grey, slightly translucent; fringe between R1 and Cu2 ochraceous yellow and blackish brown; wing venation similar to forewing but CuP reaching margin; A weak, not reaching margin.

LEGS: All legs densely setose with ochraceous and dark brown hairs, lacking spurs; hind tibia slightly broadened and dorsally densely covered with ochraceous 5 to 6 mm long scent-brushes.

GENITAL STRUCTURES: In caudal view tegumen triangular elongated towards the inner process. Dorsal process of tegumen obtusely lobed and only weakly sclerotised. Caudal margin of tegumen curved outwards in basal half, but almost straight dorsoventral in inner half (in caudal view). Margin of tegumen curved caudally along inner half displaying a row of coarse, sclerotised lobes (in lateral view). The caudal margin sclerotised dark brown to almost black; the inner half, particularly including the inner process, fully sclerotised. Base of vinculum with an oval shaped dilation. Saccus with a median indentation. Valve densely hairy, base sclerotised dark brown with single acute spine diverging from valve at 1/4 of the length of valve. Juxta slightly trapezoidal widening at base, posterior edge rounded with a median indentation. Aedeagus not sclerotized.

Female. Description based on paratype ( Figs. 4–5 ). Similar to male with the exceptions described below.

SIZE: Wingspan: 41.5 mm; forewing length: 19.0 mm; hindwing length: 17.0 mm; body length: 16.0 mm.

ANTENNAE: Uniformly red-brown.

BODY: Hairs on thorax yellow caudally.

FOREWINGS: Silver-grey coloured with extensive grey-white, rust coloured and black markings; most black spots fringed by a thin rust-brown line; sub-terminal fascia grey-white extending uninterrupted from R2 to A, basally accompanied by a series of black oval to reniform spots; mosaic of black, rust-brown and silvergrey patches at middle of wing reaching base of wing; costa accompanied by series of small grey-white and rust coloured spots; fringe from R1 to Cu2 beige and brown; dorsum edged grey. Wing venation as in male, but crossvein between R5 and M not reaching M1.

HINDWINGS: Fringe between R1 and Cu2 beige and brown; wing venation as in male.

LEGS: All legs densely setose with ochraceous hairs, lacking spurs.

GENITAL STRUCTURES: Lateral arms of prevulvar sclerite semicircular; preanal sclerite of oval shape with acute, sclerotised apex and blunt dilatation in middle of interior edge, densely setose; intergenital lobe bluntly bilobed dorsally and more acutely bilobed ventrally, densely setose.

Holotype. Male, labelled: Bhutan, Namna, N 27°44’02.3’’ E 89°23’32.2’’; Altitude 4,750 m a.s.l., 16.vii.2008, 19:10, N. Maczey leg., 10005.

Paratypes (same data as holotype except collection date and label nr.). female, 16.vii.2008, 10010; male, 03.vii.2007, 19:10, 10001; female, 06.vii.2007, 19:30, 10002; female 01.vii.2007, 19:20, 10003; female, 02.vii.2007, 19:35, 10004; male, 16.vii.2008, 19:15, 10006; male, 13.vii.2008, 19:10, 10007; male, 15.vii.2008, 19:15, 10008; male, 16.vii.2008, 19:15, 10009.

Diagnosis. Thitarodes namnai is a typical medium-sized and slightly dimorphic representative of its genus. Males are on average smaller than females and their forewings tend to be predominantly rust brown whereas females appear more often predominantly silvery-grey ( Figs. 6–13 ). Male genitalia show the diagnostic features as designated in the original description of the genus ( Figs. 14–23 ). Within the Thitarodes species described so far this species can readily be identified in the field by its characteristic two large spots in the forewing bordering vein A in a straight line. This gives both males and females a typical four-spotted appearance when adults are in a resting position. Equally, shape and position of these four spots differ significantly when compared with museum specimens of closely related species prepared according to standards.

Discussion. RELATED SPECIES FROM NEPAL. Size and colour scheme are similar to Thitarodes danieli and T. eberti , both described from lower altitudes than T. namnai . However, the two contrasting colours of wing fringes are more evenly alternating within T. namnai whereas in T. danieli and T. eberti the dark colour is significantly reduced in both fore- and hindwings. The sub-terminal grey fascia is not accompanied by a continuous dark line or line of spots at the basal side in T. eberti and T. danieli ; both of these species show here only a few irregular dark spots. A large black spot in the cell between veins Cu2 and A has a more or less straight to concave margin along vein A, but is widely curved convexly along Cu 2 in T. namnai . In T. eberti and T. danieli the margin of the same black marking is broadly curved and convex along vein A but straight along Cu2. There are distinctive differences in the male genital structure between all three species described from Nepal. The main differences from T. eberti , the species with the greatest similarity to T. namnai , are a narrower tegumen, a curved spine on the valve, the rounded median dilatation of vinculum and a missing median indentation of the saccus of the vinculum in T. eberti . Main differences to T. danieli and T. dierli are the shape of the tegumen, which is deeply bilobed in T. danieli and much wider with a heavily sclerotized and finely serrated edge in T. dierli , and a different position of the spine on the valve in both species.

RELATED SPECIES FROM CHINA. Thitarodes namnai seems to be closely related to a group of species recently described from Tibet and Sichuan including T. gonggaensis Fu & Huang , T. jialangensis Yang , Hepialus namliensis Zhu & Wang , H. namensis Zhu & Wang , and H. hainanensis Zhu & Wang ( Fu et al. 1991, Yang 1994, Zhu et al. 2004). However, all differ distinctly in the shape of the male genitalia as well as the shape and pattern of forewings and wing venation from T. namnai . Wing venation in T. jialangensis and H. namensis are similar to T. namnai but the shape of the sacculus and the position of the spine on the valve differ. The species probably closest to T. namnai is T. gonggaensis . This species has been described from Sichuan and is reputedly at the heart of recently reported successful artificial rearing methods for Ophiocordyceps sinensis in China. Differences from T. namnai can be summarized as follows. Wing shape and pattern: The apex of forewings is much more rounded in T. namnai in comparison with T. gonggaensis . The large black spot filling the cell between vein A and the dorsum, present in all specimens recorded from Namna, is missing in T. gonggaensis . The black spot filling the cell between Cu2 and A in the exterior half is more rudimentary in T. gonggaensis and of a more reniform shape with a rounded posterior edge. A greywhite colouring of the stigma is absent in T. gonggaensis . Male genitalia: The single spine on the valve is inserted at a distance of 1/5 of the total length of the valve from the base in T. namnai , but much closer to the base in T. gonggaensis . This spine of the valve is considerably straighter and longer in T. namnai . The ushaped median indentation in the saccus of the vinculum of T. namnai is missing in T. gonggaensis . The valve is not hairy in T. gonggaensis but is intensely so in T. namnai . Wing venation: The terminal branch of CuP in T. gonggaensis is not reaching A as in T. namnai .

It has to be pointed out that morphological features, including the male genitalia, can vary significantly between specimens of a single Thitarodes species. Based on incomplete knowledge of Thitarodes , it is possible that T. namnai may actually represent a subscpecies of or geographic variation within T. gonggaensis .

RELATED SPECIES FROM JAPAN. So far only one species ( T. nipponensis Ueda ) of Thitarodes has been described from Japan ( Ueda 1996). This species has wing venation similar to that of T. namnai , but it differs significantly in the shape of the male genitalia, particularly the valves.

Figures

FIGURE 24. Thitarodes namnai: underside holotype, showing wing venation, label 10005.

FIGURES 1 – 5. Thitarodes namnai: 1. holotype, male, label 10005; 2. & 3. holotype genitalia in caudal (2) and laterocaudal (3) view; 4. paratype, female, label 10010; 5. female paratype genitalia.

FIGURES 6 – 13. Thitarodes namnai: 6 – 10. paratypes males; 6. label 10001; 7. label 10006; 8. label 10007; 9. label 10008; 10. label 10009; 11 – 13. paratypes females; 11. label 10002; 12. label 10003; 13. label 10004.

FIGURES 14 – 23. Thitarodes namnai, male genitalia, paratypes: 14 – 18. caudal view; 19 – 23. latero-caudal view; 14. & 19. label 10001; 15. & 20. label 10006; 16. & 21. label 10007; 17. & 22. label 10008; 18. & 23. label 10009.