Lithosiccia, Volynkin, 2023

Volynkin, Anton V., 2023, Lithosiccia, a new genus with four new species from mainland Africa (Lepidoptera: Erebidae: Arctiinae: Lithosiini), Ecologica Montenegrina 65, pp. 24-39 : 26-27

Lithosiccia gen. n.

https://zoobank.org/ urn:lsid:zoobank.org:act:12B9A5B3-152F-4870-AEA4-E924A0CC5ED0

Type species: Lithosiccia smithi sp. n.

Diagnosis. The new genus is hereby assigned to the tribe Cisthenina and its species ( Figs 2–15 ) are externally reminiscent of Palaeosiccia (type species: Palaeosiccia punctata Hampson, 1900 ) ( Figs 16, 17 ) due to their relatively broad forewing and the bipectinate male antenna but are distinguished by the brown or ochreous forewing ground colour (it is off-white or pale greyish in Palaeosiccia ), and the dark, greyish-brown or grey hindwing ground colour in males, which is markedly paler, off-white or slightly suffused with grey in the similar genus. Compared to another Cisthenina genus occurring in the Afrotropics, Siccia (type species: Siccia caffra Walker, 1854 ) ( Figs 18, 19 ), species of Lithosiccia have a relatively broader and darker coloured forewing, but the reliable generic identification requires the examination of the copulatory organs. The male genital capsule of Lithosiccia ( Figs 20–29 ) is distinguished from both Palaeosiccia ( Fig. 30 ) and Siccia ( Fig. 31 , see also Volynkin (2023)) by the structure of the valva, which is clearly subdivided into the broad and long sacculus with an elongate and narrow distal process, and the costa extended distally into a narrow sclerotised process (called the ‘cucullus’ herein). Additionally, the tegumen of Lithosiccia has broad but weakly sclerotised lobes anteriorly, which protrude into the intersegmental membrane connecting the genitalia with the abdomen cuticle, the feature characteristic of the genus. Another feature characteristic of the genus is the ductus ejaculatorius opening on the ventral side of the phallus whereas in Palaeosiccia , Siccia and other related genera, it opens dorsally. The female genitalia of the new genus ( Figs 32, 33 ) are distinguished from Palaeosiccia ( Fig. 34 ) by the lack of the antevaginal plate and the lateral subostial plates, the corpus bursae bearing broad and dense clusters of robust spines, and the well-developed appendix bursae situated laterally or postero-laterally whereas it is reduced and situated postero-ventrally in the aforementioned genus. Compared to Siccia ( Fig. 35 , see also Volynkin (2023)), the female genitalia of Lithosiccia lack the lateral subostial lobes. Additionally, the 8 th and the 7 th abdominal sternites of Lithosiccia bear lateral gelatinous pockets which are not found in Palaeosiccia or Siccia .

Description. External morphology of adults. Male antenna shortly bipectinate, female antenna setose-serrulate. Body brown. Forewing ground colour from pale ochreous brown to deep brown. Forewing markings dark brown or blackish. Transverse lines irregularly zigzagged or sinuous, indistinct in certain species. Proximal cellular spot small, dot-shaped. Discal spot large and various in shape. Hindwing brown or greyish-brown, discal spot diffuse. Male genitalia. Uncus elongate and slender, medially dilated and distally tapered, with tiny claw-shaped tip. Tuba analis weakly setose. Arms of tegumen fused in dorsal third and anteriorly tapered, with broad but weakly sclerotised lobes anteriorly protruding into the intersegmental membrane. Vinculum shorter than tegumen, more or less U-shaped. Valva clearly subdivied into dorsal and ventral (saccular) parts. Dorsal part of valva distally narrow and well-sclerotised, downcurved in certain species. Sacculus broad, with setose or spinulose dorsal margin. Distal saccular process elongate and narrow, almost straight. Juxta weakly sclerotised, trapezoidal, in certain species with two short and serrulate apical processes. Phallus large, cylindrical, almost straight or slightly upcurved distally. Ductus ejaculatorius originates anterio-ventrally. Vesica broad, sack-like, with short diverticula of various shapes, and large horn- or plate-like distal cornutus; in certain species with additional proximal plate-like cornutus or cluster of spines. Female genitalia. Papilla analis broad, trapezoidal, weakly setose. Apophyses long and thin. Postvaginal area with scobinated cluster. Ostium bursae broad. Ductus bursae short and broad, weakly sclerotised, with short gelatinous antrum in certain species. Corpus bursae with sclerotised posterior and membranous anterior sections, former bearing clusters of numerous robust spines protruding into anterior section laterally in certain species. Appendix bursae short, situated postero-ventrally or laterally, basally spinulose in certain species. 7 th (and 6 th in certain species) abdominal sternite(s) with lateral gelatinous pockets.

Molecular data. The pairwise distances between morphospecies are in the range of 4.11–8.77%. At the current stage it is impossible to evaluate the intrapopulational divergences due to the limited number of specimens sampled, the only example available being two specimens of L. juvenis from Guinea which have identical COI sequences. The intraspecific divergences between different populations of the same species vary significantly with pairwise distances in the range of 0.46–3.95% ( Fig. 1 ) .

Distribution. Species of the genus are distributed in rainforests of West and Central Africa.

Etymology. The genus name is an aggregate of the genus-group names Lithosia Fabricius, 1798 and Siccia and refers to the close relationship with Siccia and the valva clearly subdivided into the dorsal and ventral parts like in many genera of the subtribe Lithosiina .

Figures

Figure 1. Phylogenetic tree of the genus Lithosiccia from Afrotropics recovered from the ML analysis of COI barcodes.

Figures 2–10. Lithosiccia spp.: adults. Depositories of the specimens: 2 in CMNH (photo by V. Verdecia); 3 in GMF- B; 4, 7 and 8 in NHMUK (©The Trustees of NHMUK); 5, 6, 9 and 10 in ANHRT.

Figures 11–19. Lithosiccia smithi (11–15), Palaeosiccia punctata (16, 17), and Siccia caffra (18, 19): adults. Depositories of the specimens: 11–13 and 17 in ANHRT; 14 and 15 in GMF-B; 16 and 19 in NHMUK (©The Trustees of NHMUK); 18 in MfN.

Figures 20–22. Lithosiccia juvenis: male genitalia. Depositories of the specimens dissected: 20 in ANHRT; 21 in GMF- B; 22 in NHMUK (©The Trustees of NHMUK).

Figures 23–25. Lithosiccia spp.: male genitalia. Depositories of the specimens dissected: 23 in ANHRT; 24 and 25 in NHMUK (©The Trustees of NHMUK).

Figures 26–28. Lithosiccia spp.: male genitalia. The specimens dissected are deposited in ANHRT.

Figures 29–31. Lithosiccia smithi (29), Palaeosiccia punctata (30), and Siccia caffra (31): male genitalia. Depositories of the specimens dissected: 29 and 30 in ANHRT; 31 in HNHM.

Figures 32–35. Lithosiccia spp. (32, 33), Palaeosiccia punctata (34), and Siccia caffra (35): female genitalia. Depositories of the specimens dissected: 32 and 34 in ANHRT; 33 in GMF-B; 35 in MfN.