Metarctia (Metarhodia) bemba, László & Volynkin, 2024

László, Gyula M. & Volynkin, Anton V., 2024, Three new species of the Metarctia Walker subgenus Metarhodia Kiriakoff from Zambia and Republic of Congo (Lepidoptera: Erebidae: Arctiinae: Syntomini), Ecologica Montenegrina 77, pp. 180-191 : 188-191

Metarctia (Metarhodia) bemba sp. n.

https://zoobank.org/ urn:lsid:zoobank.org:act:A4EA601A-CA3A-4B12-9E87-06DA6E6DA346

( Figs 11–12 , 19–20 )

Holotype. ♂, “ ZAMBIA 1420m / Chilambwe Falls , Kafubu River / 09°50'13"S, 30°43'35"E / 8- 12.ii.2019 Actinic Light Trap / Dérozier, V., Mulvaney, L., / Smith, R., Takano, H. Leg. / ANHRT:2019.4” // unique id.: ANHRTUK 00185685, gen. slide No.: LG 6458 ( ANHRT).

Paratypes. Zambia. 1 ♂, with the same data as the holotype, gen. slide No.: LG 6452 ; 1 ♂, Muchinga Province, Jombo village , 10°27'01"S, 33°14'30"E, 30.xi.–05.xii.2023, MV light trap, Bashford, M., Collins, A., László, G., Volynkin, A. leg., ANHRT :2024.3; 1 ♂, Muchinga Province, 30 km North of Mpika, Danger Hill , 1684m, 11°37'38"S, 31°33'56"E, 13–15.xii.2023, MV light trap, László, G., Morgan, L., Volynkin, A. leg., ANHRT : 2024.3, gen. slide No.: LG 6456 ( ANHRT) .

Description.

External morphology of male adult ( Figs 11–12 ).

Forewing length 14–15 mm. Antenna pale cream, bipectinate, rami twice as long as diameter of antenna shaft. Head small, compound eyes relatively large. Proboscis absent, labial palps short, porrect. Labial palps, frons, vertex, collar, uniformly dark brown, tegulae, mesothorax and legs somewhat paler; index of very short spurs 0-2-2. Forewing elongate, costal and anal margin straight, termen evenly arcuate, apex rounded; ground colour rust brown with darker costa and dark brown blotch at distal end of cell. Transverse lines indiscernible except for very thin, continuous, grey terminal line; fringe brownish grey. Forewing underside ochreous-brown darkening towards termen, costal margin dark brown. Hindwing short and narrow, elongate with rounded apex and anal margin; uniformly pale pinkish orange without transverse lines and discal spot; fringe pale ochreous. Hindwing underside ochreous brown with slightly darker greyish brown dorsal area. Abdomen uniformly rust brown without marking.

Male genitalia ( Figs 19–20 ).

Uncus stout, proximal half slightly bulged dorsad, setose, distal half dilated dorsoventrally into a longitudinal dorsal crest with margin distally curved ventrad, ventrally with two short longitudinal lateral lobes, apex truncate. Tegumen moderately long and narrow. Juxta large, somewhat X-shaped with short, broad apically truncate anterolateral, and larger, triangular posterolateral lobes enclosing a narrow V- or U-shaped medial incision with heavily sclerotised, rugged ridge-like margin. Vinculum short, saccus short and narrow, rounded. Valva moderately broad basally, split into three elongate processes: costal process short, digitiform, medially tapered, bearing a cluster of long, needle-like setae apically; cucullus (medial process) ca. 2.5 times longer than costal process, narrow at base, slightly tapered distally, slightly arched medially, apex rounded with dense group of fine, long, acute setae, gradually shortening proximad on ventral margin; saccular process ca. half as long as cucullus, very narrow digitiform, gently arched with pointed apex; ventral side covered in fine setae. Phallus short and narrow, straight; coecum penis with elongate-quadrangular process, taking up ca. one-third the length of entire phallus with two short rounded lobes apically; carina absent. Vesica with short slightly inflated basal section possessing a very short pocket-like ventral diverticulum, and two small, sack-like dorsolateral diverticula, subbasal section of vesica with a short triangular cornutus, medial section with a weakly sclerotised area continued in proximal part of vesica ejaculatorius.

Female unknown.

Diagnosis. Metarctia (Metarhodia) bemba sp. n. is reminiscent of M. (M.) lunda sp. n. but it is considerably smaller in size and shows a slightly paler forewing ground colour. In the male genitalia, the two species are readily distinguished by the noticeably shorter and narrower costal process, the slightly shorter cucullus, the markedly shorter saccular process of the valva and the considerably narrower juxta in M. (M.) bemba sp. n. compared to those of M. (M.) lunda sp. n. In the vesica structures, M. (M.) bemba sp. n. has a noticeably larger cornutus and shorter diverticula than in M. (M.) lunda sp. n.

Etymology. This new species is named after the Bemba people, the largest ethnic group of Zambia inhabiting primarily the northeastern regions of the country. The name is a noun in the nominative case. Distribution ( Fig. 23 ). The type material of Metarctia (Metarhodia) bemba sp. n. was collected in the northeastern areas of Zambia in diverse mosaics of Miombo woodlands, riverine forests (mushitu) and marshlands.

Discussion

The subgenus Metarhodia of Metarctia is phenotypically characterised by the dark brownish forewing, the pale ochreous to orange hindwing colouration and the conspicuously short rami of the male antennae. The shared male genitalia feature of the subgenus is the trilobate valva displaying a narrow, digitiform, apically setose costal process, an elongate, narrow cucullus as a medial process of the valva and a well-defined saccular lobe or process. As a result of this study, a well-defined species group comprising M. (M.) jordani , M. (M.) lunda sp. n., M. (M.) sangha sp. n. and M. (M.) bemba sp. n. can be delimited with species possessing cream-coloured antennae and considerably longer cuculli as well as narrower, more elongate saccular processes than is observed in the other members of the subgenus (cf. Przybyłowicz 2009). The species of this complex show an allopatric distribution pattern in central- and southern-central Africa and the relatively limited morphological divergence of these taxa may suggest a recent radiation. Additional research is required to specify the exact distribution range of these species and discoveries of further species of this complex cannot be ruled out.

Acknowledgements

In the Republic of Congo, our cooperative partner, the Wildlife Conservation Society (WCS) Congo and their employees authorised research in NNNP and provided diverse administrative and technical support during the expedition. We express our gratitude to the following WCS staff: Morgane Cournarie (Program coordinator), Vittoria Estienne (Director of Research and Biomonitoring), Ben Evans (Park Director), Richard Malonga (Director), Onesi Samba (Research Assistant), Yako Valentin (Administrative Manager), Tatiana Thomas (Camp Manager, Mondika). The authors are also grateful to Joseph Goma-Tchimbakala (General Director of IRSEN, Institut National de Recherche en Sciences Exactes et Naturelles), for issuing the necessary research and export permits and Jean Bosco Nganongo (Directeur de la DFAP Direction de la Faune et des aires protégées), for issuing CITES permits. We further thank Victor Mamonekene (Hydrobiologist, Ichthyologist, IRSEN and Marien Ngouabi University) for his valuable assistance. Last but not least, we are indebted to Violette Dérozier who very ably organised ANHRT’s series of expeditions conducted in NNNP.

In Zambia, Rhoda Kachali ( Department of National Parks and Wildlife – ZAWA, Lusaka), Claire Mateke and Martha Imakando (Livingstone Museum, Livingstone) are thanked for the diverse administrative and technical assistance provided during fieldwork as well as for issuing the research and export permits .

Alberto Zilli and Geoff Martin (NHMUK) are thanked for kindly facilitating access to the Syntomini type and accession materials under their care. The image of the holotype of Metarctia jordani is reproduced with permission from the Trustees of the Natural History Museum, London and made available under Creative Commons License 4.0 (https://creativecommons.org/licenses/by/4.0/). The authors declare that to the best of their knowledge they conform to the national regulations and meet with the conditions and requirements of International Conventions concerning collecting/export and handling of the specimens presented in this Article.

References

Fiebig, R., László, G.M., Volynkin, A.V. & Taberer, T.R. (2023) Integrative taxonomic revision of the Metarctia Walker, 1855 subgenus Hebena Walker, 1856, with descriptions of six new species and one new subspecies (Lepidoptera: Erebidae: Arctiinae: Syntomini). Zootaxa, 5339 (4), 301– 354. https://doi.org/10.11646/zootaxa.5339.4.1

Kiriakoff, S.G. (1953) Les Thyretide du Musée Royal Congo Belge (Lepidoptera Notodontoidea). Annales du Musée Royal du Congo Belge, 8 (26), 1–91.

Kiriakoff, S.G. (1957) New Thyretidae (Lepidoptera Notodontoidea). Tijdschrift voor Entomologie, 100 (1), 95–114.

Kiriakoff, S.G. (1960) Lepidoptera Fam. Thyretidae. Genera Insectorum, 214e, 1–66.

Lafontaine, J. D. & Mikkola, K. (1987) Lock-and-key systems in the inner genitalia of Noctuidae (Lepidoptera) as a taxonomic character. Entomologiske Meddelelser, 55 (2–3), 161–167. [in Swedish with English abstract]

Ochse, M. (2017) Arctiinae der Subtribus Thyretina in der westafrikanischen Regenwaldregion (Erebidae). Nachrichten des Entomologischen Vereins Apollo, 38 (1), 1–22.

[https://www.zobodat.at/pdf/NEVA_38_0001-0022.pdf]

Przybyłowicz, Ł. (2009) Thyretini of Africa. An illustrated Catalogue of the Thyretini (Lepidoptera: Arctiidae: Syntominae) of the Afrotropical Region. Entomonograph, 16, Apollo Books, Denmark, 170 pp.

Spitsyn, V.M. (2024) A new species of the genus Metarctia Walker, 1855 from Zanzibar Island (Erebidae: Arctiini: Syntomini). Ecologica Montenegrina, 75, 85–88.

https://doi.org/10.37828/em.2024.75.7

Volynkin, A.V. (2024) On the terminology of the genitalia structures of lichen moths (Lepidoptera: Erebidae: Arctiinae: Lithosiini) with some references to Noctuidae. Ecologica Montenegrina, 73, 176–207. https://doi.org/10.37828/em.2024.73.18

Walker, F. (1855) List of the of Lepidopterous Insects in the Collection of the British Museum. Part III. Lepidoptera Heterocera, 3, i–iv., Printed by the order of Trustees, London, 583–775.

Walker, F. (1856) List of the of Lepidopterous Insects in the Collection of the British Museum. Part VII. Lepidoptera Heterocera, 7, i–iv., Printed by the order of Trustees, London, 1509–1808.

Figures

Figures 23. Distribution of the taxa of the Metarctia (Metarhodia) jordani species-group.

Figures 7–12. Adults (all in coll. ANHRT). 7. Metarctia sangha sp. n., HT, ♂. 8. Id., PT, ♂. 9. Id., PT, ♂. 10. Id., PT, ♀. 11. M. bemba sp. n., HT, ♂. 12. Id., PT, ♂.

Figures 19–22. Male (19–20) and female genitalia (21–22) (all in coll. ANHRT). 19. Metarctia bemba sp. n. HT, LG 6458. 20. Id., PT, LG 6452. 21. M. lunda sp. n., PT, LG 6449. 22. M. sangha sp. n., PT, LG 6463.