Acanthosia Krüger, 2015

Genus Acanthosia Krüger, 2015 View in CoL , stat. n.

Archithosia (Acanthosia) Krüger, 2015 , Transvaal Museum Memoir, 15: 28 (Type species: Phryganopsis tryphosa Kiriakoff, 1958 View in CoL , by original designation).

Remarks. (1) Species of the genus are externally polymorphic and no reliable diagnostic external features were found. As the species’ ranges are overlapping, identification requires the dissection of all specimens examined. In the male genitalia structures, a significant range of intraspecific variability was found in the length and width of the distal saccular process and its proximal lobe, which was observed even within the same population and therefore has no taxonomic value. (2) The only species of the genus unstudied during the present work is A. similis Birket-Smith, 1965 described from Mount Cameroon. According to the original description ( Birket-Smith 1965), it has a male genital capsule ground plan very similar to A. tryphosa with the only difference between the two species being the ampulla shape, which is more elongate, thorn-shaped, and dentate in A. similis but short and crest-like in A. tryphosa . In the ANHRT collections, there is a short series of Acanthosia specimens from northern Malawi (Mzuzu Wildlife Sanctuary) with the male genital capsule clearly matching the original description of A. similis . However, considering the geographic remoteness and the fact that the vesica structure of A. similis remains unknown, it is currently impossible to identify the Malawian population until Cameroonian specimens of A. similis are examined. (3) Birket-Smith (1965) placed Phryganopsis flavifrontella Strand, 1912 in Archithosia sensu lato based on the incorrect treatment of the taxon, which was caused by the erroneous identification of certain Acanthosia species as flavifrontella . This treatment was followed by Krüger (2015), who associated flavifrontella with his new subgenus Acanthosia of Archithosia . Nevertheless, the type specimen of flavifrontella is clearly not congeneric with the type species of Acanthosia and therefore this species is excluded from Acanthosia and placed in a new genus Flavifronthosia gen. n. described below in the present paper. In turn, the “ Archithosia flavifrontella ” sensu Birket-Smith (1965) and Krüger (2015) is an Acanthosia species new to science and is also described below in the present paper as Acanthosia pervolgata sp. n.

Diagnosis. Members of the genus ( Figs 3–33 View Figures 1–15 View Figures 16–30 View Figures 31–42 ) are medium-sized moths with forewing ground colour varying from ochreous brown to dark brown and the forewing pattern expressed as two irregular dark spots on the costal margin and anal vein postmedially, and fuscous suffusion between them, which sometimes forms a diffuse, angled transverse fascia. The genital structures of Acanthosia are characterised by the combination of the following features. Male ( Figs 90–109 View Figures 89–93 View Figures 94–97 View Figures 98–101 View Figures 102–105 View Figures 106–109 ). (1) The uncus has a swollen proximal section and a narrow and straight distal section terminating with a small, claw-shaped tip (reminiscent of Architesma , in which, however, the swollen uncus is gradually tapered and downcurved distally). (2) The scaphium is string-like and weakly sclerotised. (3) The tegumen is downcurved and its arms are anteriorly strongly dilated and fused in their anterior half (vs. two-thirds in Archithosia ). The dorsal ends of the arms have narrow sclerotised plates extending dorso-posteriad into the base of the tuba analis towards the base of the scaphium (similar to Architesma ). The ventral ends of the arms of the tegumen are flattened and tapered (unlike Archithosia , in which they are rounded and swollen). (4) The vinculum has laterally flattened and strip-like arms. (5) The dorsal section of the valva is deeply separated from the sacculus and fused with it only in the basal section of the valva (a feature unique within the generic complex). The dorsal section is elongate and narrow with almost parallel margins, and soft as it is built by the valvula with weak secondary sclerotisation (except for the base, which is supported by the editum-costa complex and the crest connecting it with the sacculus). The secondary sclerotisation is absent only in the proximal ventral region of the valvula (near the junction with the sacculus), which is membranous and folded. (6) The tendon is very short, flattened, trapezoidal and well-sclerotised, while the main part of the diaphragmal section of the transtilla is membranous and fold-like. (7) The costa is short and mostly supports the basal section of the outer wall of the dorsal section of the valva while on the inner wall, at the dorsal corner of the valva base, the costa is fused with the very short editum forming an editum-costa complex with a membranous medial part and bearing a short, crest- or thorn-shaped ampulla directed inwards (a feature unique within the generic complex). (8) The editum-costa complex is connected to the sacculus by the transverse weakly sclerotised crest, the nature of which is unclear. Most probably, it is a ventral protrusion of the editum but it may also be homologous to the lamella centralis of a number of other Lithosiina genera. (9) The basal saccular process is thin and weakly sclerotised, its proximal half is fused with the intersaccular membrane along the lateral margin of the juxta, while the distal (free) section arises above the top of the juxta and stretches along the phallus. (10) The distal saccular process is large, well-separated from the valvula, heavily sclerotised and with a densely scobinate inner surface of its distal (main) lobe. Its proximal section is dilated and its dorsal margin bears a sparsely serrulate proximal process directed dorsad. (11) The ental ends of the sacculi are elongate and connected by a gelatinous or weakly sclerotised intersaccular bridge (similar to Architesma ). (12) The juxta is small and weakly sclerotised, consisting of two plates apically connected by a thick membrane. The ventral corner of the juxtal plate is articulated with the base of the sacculus by a gelatinous suture. (13) The anellus is membranous. (14) The phallus is relatively narrow, shorter than the tegumen-vinculum complex, with a broad and rounded coecum and a ventral plate-like carina extending into the base of the vesica and slightly protruding apically. (15) The vesica is membranous and has a large, sack-like or utricular ventral subbasal diverticulum and a distal (main) diverticulum with one or two small subdiverticula, and bearing a small thorn-shaped terminal cornutus apically. Female ( Figs 151–155 View Figures 150–155 ). (1) The 8 th tergite is moderately sclerotised and band-like while the 8 th sternite is membranous and connected to the sterigma by the gelatinous folds. (2) The postvaginal formation of the sterigma is broad and long with a flattened and smooth medial plate and swollen lateral margins, which are fused with the antevaginal part of the sterigma, which is a swollen, weakly sclerotised and rugose, semilunar fold encircling the ostium bursae ventrally. The structure of the sterigma of Acanthosia is similar to Architesma but in the latter the posterior section of the postvaginal formation is finely scobinate and in most species swollen whereas it is smooth in Acanthosia . (3) The ductus bursae is very short, dorso-ventrally flattened and sclerotised (unlike in Archithosia , in which only the ventral side of the ductus bursae is sclerotised). (4) The posterior section of the corpus bursae is considerably narrower than the anterior one, tubular (somewhat posteriorly dilated in certain species), and has a broad area of sclerotisation laterally or around its entire circumference. An additional narrow area of weak sclerotisation may be present posteriorly at the base of the appendix bursae. (5) The anterior section of the corpus bursae is elliptical or globular, membranous and finely scobinate, and with a small signum dorsally. (6) The appendix bursae is short, conical or semiglobular, membranous, covering the ductus bursae ventrally.

Distribution. The genus is widespread in the Congolian and Zambezian Regions from south-eastern Guinea in the west to eastern Tanzania in the east, and reaching northern Malawi in the south.