Achyra melanostictalis (Hampson in Poulton 1916) (Pionea), 2022

Mally, Richard, Aarvik, Leif, Karisch, Timm, Lees, David C. & Malm, Tobias, 2022, Revision of Afrotropical Udea Guenee in Duponchel, 1845, with description of five new species of the U. ferrugalis (Huebner, 1796) group (Lepidoptera, Crambidae, Spilomelinae), Nota Lepidopterologica 45, pp. 315-353 : 315

Achyra melanostictalis (Hampson in Poulton 1916) (Pionea) comb. nov.

Figs 9 , 19 , 32

Pionea melanostictalis Hampson in Poulton 1916: 175, pl. 2 fig. 46. Type locality: Somalia, Mandheera.

Material examined.

Lectotype (here designated): Somalia • 1 ♀; Somaliland , Mandera, SW of Berbera; 914 m a. s. l.; 23 Sep. 1908; W. Feather leg.; "TYPE LEP: No 1212 Pionea 1/2 Pionea melanostictalis Hampson"; Mally genitalia dissection no. 1169; unique specimen identifier LEPI 1212 1/2; OUMNH . • Paralectotype: 1 ♀; same data as for lectotype; 27 Sep. 1908; "TYPE LEP: No 1212 Pionea 2/2 Pionea melanostictalis Hampson"; unique specimen identifier LEPI 1212 2/2; OUMNH .

Diagnosis.

Achyra melanostictalis is readily distinguished from African Udea species by its wing pattern in combination with the dark, uniform hindwings lacking any stigmata. The species is preliminarily placed in Achyra based on commonalities in the wing pattern. It is distinguished from A. coelatalis (Walker, 1859) and A. arida Maes, 2005 by the clearly different wing pattern; see for example https://lepiforum.org/wiki/page/Achyra_coelatalis for A. coelatalis , and Maes (2005) for A. arida . With A. nudalis ( Hübner, 1796), A. melanostictalis shares similarities in wing pattern, and in the female genitalia in the attachment location of the appendix bursae. However, the former species is distinguished from the latter in the female genitalia by two short ovate to lanceolate signa, and by the long, coiled ductus bursae. The two species share a rounded structure in the posterior female genitalia; in A. melanostictalis , however, this is the antrum, whereas in A. nudalis this structure is located in the posterior ductus bursae, before the colliculum and antrum. The species further resembles certain species of Tegostoma Zeller, 1847 ( Odontiinae ), like T. comparalis ( Hübner, 1796) and Tegostoma sp. ABA4625 in the BOLD database, in wing shape, maculation and the uniformly coloured hindwings without maculation. Achyra melanostictalis can be best distinguished from T. comparalis in the female genitalia by the structure of the antrum, and the presence of an appendix bursae as well as a signum (see e.g. Chen and Wang 2013 for illustrations of the female genitalia of T. comparalis ). The unusual signum (Fig. 32 ) of A. melanostictalis is not shared with any other Spilomelinae , Pyraustinae or Odontiinae that we know of, and may therefore act as the most unambiguous character to identify and distinguish this species.

Description of adults.

Head: Light brown; labial palps long, straight anteriad, basal meron cream-coloured, second and third merons brown; maxillary palps brown, long enough to touch each other at apex; haustellum well developed, with cream-coloured scaling at base; frons flat, brown with white lateral margins; complex eyes large, occupying the entire sides of head, hemispherical; ocelli present behind antenna base near compound eye; antennae cream-brown, with white ciliae almost as long as half antennomere diameter. Thorax: Dorsum dirty-greyish like wing colour, venter cream-white like basal meron of labial palps. Legs cream-white; midleg outer tibial spur about 2/3 length of inner spur; hindleg proximal pair with long inner spur and outer spur half as long, distal pair with outer spur 2/3 length of inner spur. Wings: (Fig. 9 ) Forewing length of females 7.5 mm. Female with two frenulum bristles. Forewing upper side light brown, costa darker brown; maculation dark brown, fairly clear; antemedial line narrow, from 1/4 of forewing length running in a zigzag line from below costa towards 1/3 of anal margin, in centre with a larger spike towards wing base, and basal of its tip a short streak; proximal discoidal stigma a small oval dot, distal discoidal stigma a short zigzag line spanning breadth of cell; postmedial line narrow, in costal third of its course with a wide amplitude, then fading and turning towards wing base under discoidal stigmata before becoming a more clear, broader line again that turn straight towards anal margin under discoidal stigmata; terminal area with a band of outward-directed brown spikes, retracing the zigzag pattern of postmedial line; termen with dark brown wedge-shaped markings alternating with terminal area’s brown spikes; fringe basally narrowly light brown, followed by a narrow, slightly darker brown band, distal half pale brownish. Underside of forewings light brown, framed by slim dark brown costal margin and series of brown dots of termen at end of veins; anal margin with a broad beige area and only interspersed by brown scales; pattern of upper forewing diffusely mirrored on underside, with distal discoidal streak-like stigma being the clearest feature; fringe as on upper side. Hindwings on upper side uniformly brown, with colour as in forewing costa, veins being slightly darker brown; termen a dark brown line; fringe as in forewing. Underside of hindwings basally beige, centre light brown, darker towards termen; centre with a weak discoidal brownish streak; a weak brownish postmedial line stretching across anterior 2/3 of wing; fringe as on upper side. Abdomen: Dorsum brownish, with posterior edge of segments whitish, venter cream-white. Tympanal organ (Fig. 19 ) with bullae tympanicae almost spherical; fornix tympani recessed within tympanic frame; lobulus absent; venulae secundae strongly developed, slightly diverging posteriad. Male genitalia: Unknown. Female genitalia: (Fig. 32 ) Papillae anales membranous, densely studded with relatively short chaetae; apophyses posteriores more or less straight, strongly sclerotised, about as long as apophyses anteriores; apophyses anteriores week and rather short; antrum large, posterior part consisting of two large lateral plates (opened up dorsally in Fig. 32 ) meeting at a folded ventral recess, anterior part a large circular sclerotised structure; without discernible colliculum; ductus bursae short (about half as long as corpus bursae), relatively broad, membranous, somewhat widened in middle setion; ductus seminalis small, membranous, attached at posterior ductus bursae; corpus bursae large, ovoid, membranous; complex signum running obliquely through anterior corpus bursae: signum more than twice as long as broad, central section consisting of a narrow ridge, crossed at centre by transverse narrow ridge ending in slender lobes, apices of signum each consisting of a broad semi-circular to ovoid area studded with spike-like teeth; membranous appendix bursae emerging from right side of posterior corpus bursae.

Distribution.

So far only known from the type locality Mandheera (9°54.64'N, 44°42.79'E) in the southern Sahil region of Somaliland, Somalia.

Genetic data.

Not available.

Remarks.

The species is placed in Achyra based on a personal communication with Koen Maes, who suggested this genus based on the observation of African Achyra species with similar wing maculation (pers. comm. K. Maes 11/2021). Further arguments for this generic placement are the shape of the venulae secundae and the lateral attachment of the appendix bursae to the corpus bursae, both as in A. arida Maes, 2005. On the other hand, the female genitalia posterior of the corpus bursae, with the short, uncoiled ductus bursae and the large antrum, does not correspond to the general morphology of Achyra . The wing maculation of A. melanostictalis furthermore resembles some species of the Odontiinae genus Tegostoma , but the female genitalia share no resemblance. In fact, the signum in the corpus bursae is quite outstanding in its structure and to our knowledge unprecedented among Pyraustinae , adding to the difficulty of placing this species to genus. The appendix bursae attaching laterally to the corpus bursae is a feature of Pyraustini (character 114:0 in Mally et al. 2019). We hope that by illustrating the imago and the available genitalia here, someone might recognise its similarity to (and potential relationship with) another Afrotropical species. With the transfer of A. melanostictalis , Achyra now comprises 20 species, with four of them present in the Afrotropical region ( Nuss et al. 2003-2022).

Figures

Figures 6 - 10. Adults of Afrotropical Udea species and species removed from Udea. 6. U. nicholsae Mally, sp. nov., a. holotype ♀ (ZSM); b. paratype ♀ (ZSM); 7. U. meruensis Mally, sp. nov., holotype ♂ (NHMO); 8. U. namaquana Karisch & Mally, sp. nov., a) holotype ♂ (SDEI), b) paratype ♀ (SDEI); 9. Achyra melanostictalis (Hampson in Poulton 1916), lectotype ♀ (OUMNH); 10. Lirabotys infuscalis (Zeller, 1852), holotype ♂ (NHRS). Scale bar represents 5 mm, all specimens to scale.

Figures 11 - 20. Tympanal organs of Afrotropical Udea species and species removed from Udea. 11. U. delineatalis (Walker in Melliss 1875), ♂; 12. U. ferrugalis (Huebner, 1796), ♂; 13. U. hageni Viette, 1952, ♂; 14. U. kirinyaga Mally, sp. nov., ♂; 15. U. momella Mally, sp. nov., ♂; 16. U. nicholsae Mally, sp. nov., ♀; 17. U. meruensis Mally, sp. nov., ♂; 18. U. namaquana Karisch & Mally, sp. nov., ♂; 19. Achyra melanostictalis (Hampson in Poulton 1916), ♀; 20. Lirabotys infuscalis (Zeller, 1852), ♂. Scale bar represents 500 μm, all figures to scale.

Figures 28 - 32. Female genitalia of Udea species and species removed from Udea. 28. U. delineatalis; 29. U. ferrugalis; 30. U. nicholsae Mally, sp. nov.; 31. U. namaquana Karisch & Mally, sp. nov., including 7 th abdominal segment; 32. Achyra melanostictalis. Scale bar represents 500 μm, all figures to scale.