Sycacantha Diakonoff, 1959

Feng, Weixing, Zhuang, Jialiang & Yu, Haili, 2019, Sycacantha Diakonoff, 1959 from China, with the descriptions of three new species (Lepidoptera: Tortricidae: Olethreutinae), Zootaxa 4691 (3), pp. 201-214 : 202

Sycacantha Diakonoff, 1959

Sycacantha Diakonoff, 1959: 181 . Type species: Phaecasiophora (Sycacantha) auriflora Diakonoff, 1959 (described as subgenus of Phaecasiophora ).

Sycacantha Diakonoff, 1966: 7 . Type species: Phaecasiophora (Sycacantha) auriflora Diakonoff, 1959 .

Species of Sycacantha are medium-sized moths that are easily distinguished from other Olethreutini by the mottled forewing pattern, often with a curved subapical band with short, parallel black lines. However, this wing pattern can also be found in some species of Phaecasiophora and Atriscripta . The deeply cleft socii of the male genitalia are diagnostic for Sycacantha and distinguish it from all other genera of Sycacanthae (sensu Diakonoff, 1973).

Species of Sycacantha usually have the following combination of characters. In the male genitalia the uncus is reduced or rudimentary, dome-shaped or cone-shaped; the socius is deeply cleft forming two processes of different size, covered with spines evenly or apically; the gnathos is a naked transversal band, weakly or strongly sclerotized; the valva is slender, with a bristled costal hump basally, neck distinct, or constricted in varying degree, cucullus with base projecting ventrally, like an elbow of valva; and the phallus is short, with cornuti usually a cluster of variable spines. In the female genitalia the papillae anales are broad; the sterigma has a weakly sclerotized lamella postvaginalis, aciculate, with lateral prominences directed forwards; and the corpus bursae is oval or elongate oval, with signa one, two, or no signa, and depressed patches.

Based on the character of the socii, Diakonoff (1973) divided Sycacantha into two species-groups: the S. thermographa group and the S. inodes group. However, in some species the socii are intermediate between the two types ( Diakonoff 1973; Horak 2006). Species of this study are not classified because in the new species S. camarata the socii are intermediate.

Twenty-five full-length barcodes (658bp) representing 14 species of Sycacantha and Phaecasiophora are present in GenBank (accessed 30 June 2019). In the present study, full-length barcodes of 18 exemplar specimens belonging to 14 species ( Table 1 ) of Sycacantha and Phaecasiophora from China were successfully sequenced. A NJ tree ( Fig. 1 ) based on the above 43 COI gene sequenes was constructed. The barcode sequences in the NJ tree form two distinctive clusters, a Sycacantha clade and a Phaecasiophora clade. Phaecasiophora diserta was embedded within Sycacantha and S. obtundana fell into Phaecasiophora . Although the clades were only weakly supported, the molecular data are consistent with features of the genitalia (the diagnosis will be mentioned later in this article). Thus, we proposed two new combinations. In the Sycacantha clade, COI sequences formed three clusters: the first comprised of four species (i.e., S. camarata sp. nov., S. typicusivalva sp. nov., S. diserta comb. nov. and S. inopinata ), the second of three species (i.e., S. decursiva sp. nov., S. catharia and S. complicitana ); and the third of one species (i.e., S. inodes ). This result does not agree with the species-groups proposed by Diaknoff (1973). To reveal the relationships among the species and establish species-groups, further studies are needed with more extensive taxon sampling.

The genetic distances within Sycacantha are given in Table 2 . Intraspecific divergence ranged from 0 to 1.7% among the nine species ( S. catharia , S. typicusivalva sp. nov., Sycacantha sp. B, S. sphaerocosmana , S. castanicolor , S. atactodes , S. placida , Sycacantha sp. A, and S. exedra ), and the interspecific divergence among the 19 species ranged from 0 to 11.6%. In Lepidoptera , barcode divergence of approximately 2% is generally congruent with morphology-based species-level identifications ( Hajibabaei et al. 2006; Zahiri et al. 2014). We found the genetic divergence among specimens of Sycacantha sp. B, S. sphaerocosmana , and S. castanicolor to be less than 2%, ranging from 0 to 1.7%; whereas the genetic divergence among these specimens and other species is more than 4%. So we suspect that Sycacantha sp. B, S. sphaerocosmana , and S. castanicolor might be the same species.

Figures

FIGURE 1. Neighbor-joining tree based on DNA barcodes of Sycacantha and Phaecasiophora species. Numbers above/below branches refer to bootstrap support.