Introduction

The fauna of Microlepidoptera in general and of the family Lecithoceridae in particular in the Afrotropical Region (= Ethiopian Region) have been poorly documented. The first known species of Lecithoceridae from the Afrotropical Region is Idiopteryx obliquella (Walsingham, 1881) and followed by Lecithocera flavipalpis Walsingham, 1891. Later JANSE (1954, 1963) treated 22 species of Lecithoceridae. VÁRI et al. (2002) listed 21 species of the family for the fauna of southern Africa. The taxonomic history and status of the family in the Afrotropical Region were summarized by PARK & DE PRINS (2019). In the website “http://www.afromoths.net” compiled by J. & W. DE PRINS (updated 25 April 2019), 133 species belonging to 22 genera of the family are listed. In the website, ten recently described species belonging to the subfamily Lecithocerinae from Cameroon by PARK (2018a), seven species of the subfamily Torodorinae and eight new species of the genus Ptilothyris Walsingham, 1897 described by PARK (PARK, 2018b; PARK et al., 2019) are included.

The genus Corymbus Park, gen. n. (Lecithoceridae: Lecithocerinae) is related to Notioseus Park, 2018 and Paniculata Park, 2018, both described from Cameroon. The three genera share the ochreous forewing ground colour and the 2nd segment of labial palpus having a cluster of long hair like scales which are appressed dorsally. The characters separating Corymbus Park from the above two genera and other related ones are discussed under the description of the genus.

In the present paper, six new species of Corymbus Park are described from the Afrotropical Region, and the previously known species, Eridachtha crossogramma (Meyrick, 1921), is transferred to this new genus as Corymbus crossogramma (Meyrick, 1921), comb. n.

Material and methods

The present study is based partly on material preserved in the Royal Museum for Central Africa, Tervuren, Belgium (RMCA) and partly on material collected by the third author in Kenya, Malawi, and Tanzania and which is preserved in The Natural History Museum, University of Oslo, Norway (NHMO). Additional material collected by David Agassiz in East Africa will be deposited in The Natural History Museum, London, UK (NHMUK). The type specimen of Eridachtha crossogramma (Meyrick, 1921) preserved in the Ditsong National Museum of Natural History (formerly Transvaal Museum, Pretoria) (TMSA) was examined. Dissected genitalia were mainly stained with Chlorazol black and wings were mainly stained by Double Stain containing lignin pink, acid fuchsin, GAA, lactic acid, and phenol. Both were slide mounted in Euparal. Wingspan was measured from the apex of the left wing to the apex of the right wing. The colour standard for the descriptions of adults followed KORNERUP & WANSCHER (1978).

Taxonomy

Corymbus Park, gen. n.

Type species: Corymbus deprinsi Park & Aarvik, sp. n.

Corymbus Park, 2019 is superficially similar to Notioseus Park, 2018 and Paniculata Park, 2018 sharing some diagnostic characters, including the ochreous ground colour of the forewing and the labial palpus with similar long, hair like scales appressed dorsally. However, the new genus can be distinguished from Notioseus Park by the hindwing venation with M₂ absent, but M₃ and CuA₁ stalked, whereas Notioseus has M₃ and CuA₁ clearly coalescent, and its male genitalia with a distinct ring shaped plate fused with basal lobes of the uncus. Paniculata Park differs by the presence of a prominent black scale tuft ventrally at the basal segment of the antenna, and also by the presence of M₂ in the hindwing; M₃ and CuA₁ are coalescent. The new genus also resembles the Oriental genus Eridachtha Meyrick, 1910 described from S India, which has similar rough scales on the labial palpus and similar male genitalia. However, Corymbus Park can be distinguished from Eridachtha by the forewing venation with R₃ free, and CuA₁ and CuA₂ remote from M₃, and the labial palpus which has a cluster of dorsally appressed, long, hair like scales, whereas Eridachtha has rough hairs, not appressed, above and beneath. This type of rough hairs on the labial palpus are also found in Syntetarca Gozmány, 1978 described from Malaysian Borneo, but Syntetarca has a well developed vein M₂ in the hindwing.

Adult: Head covered with pale orange scales dorsally. Antenna slightly longer than forewing; basal segment elongate, slightly dilated toward apex; flagellum orange white, filiform, not ciliate. Second segment of labial palpus with cluster of rough hair like, yellowish white to pale orange scales appressed dorsally; 3^rd segment usually shorter than 2^nd segment, pointed apically. Thorax yellowish white to pale orange. Tegula of same colour, with fuscous scales along anterior margin. Hind tibia uniformly covered with rough scales above and beneath. Forewing ground colour yellowish white to pale orange, often brownish scales scattered irregularly; fuscous discal spots weakly expressed in middle and at end, often absent; costa slightly arched; apex acute or often obtuse; termen oblique; venation (Fig. 1) with R₁ arising from about 2/5 length of cell, distance between R₂ and R₃ less than 1/3 length of that of R₂ and R₁, R₃ free arising near from upper corner of cell, R₄ and R₅ stalked for about basal 2/3, R₅ to termen, M₁ remote from R₄₊₅ at base, nearly parallel to R₄₊₅, M₂ and M₃ free, CuA₁ and CuA₂ free, A1+A2 forked at base. Hindwing yellowish white to orange white; venation with Sc and M₁ stalked for about half of their length; M₂ absent; M₃ and CuA₁ stalked.

Male genitalia: Similar to those of Lecithocera Herrich-Schäffer, 1853 and Eridachtha Meyrick, 1910. Basal lobes of uncus semiovate, usually directed distally or outwardly. Gnathos with sclerotized, broad basal plate; median process narrowed toward apex, curved downward from beyond 2/3, pointed apically. Costal bar well developed. Tegumen broad, weakly sclerotized. Valva elongate; cucullus thumb like with rounded apex; ventral margin with a small triangular process or instead slightly protruded medially. Juxta usually with slender, weakly sclerotized latero caudal lobes. Aedeagus stout, curved medially, often with apical spines on dorsal surface, no cornuti.

Etymology: The generic name is derived from Latin, corymb or Greek, κόρυµβος (= cluster), referring to the cluster of long hair like scales on the 2^nd segment of the labial palpus.

Key to the species of the genus Corymbus Park (due to the missing hind wing C. crossogramma (Meyrick, 1921) is not included in the key)

1. Hindwing with club shaped black streak centrally or irregularly scattered with black scales ... 2

- Hindwing without such streak or black scales… 3

2. Hindwing with club shaped black scales centrally; the male genitalia with a triangular, apically pointed process at lower corner of cucullus on ventral margin ... C. nigrizosterus Park & Aarvik, sp. n.

Hindwing with black scales irregularly scattered, especially along costa, centrally, and around tornus; male genitalia with a toe like process on ventral margin of basal part of valva ... C. hallicis Park & Aarvok, sp. n.

3. Valva of male genitalia with a triangular, apically pointed process on ventral margin … 4

- Valva of male genitalia without such process, instead with protrusion on ventral margin ... C. malmoius Park & Aarvik, sp. n.

4. Forewing ground colour pale orange; apex obtuse ... C. hirtitibia Park & Aarvik, sp. n.

- Forewing ground colour orange white or yellowish white; apex more or less sharply produced ... 5

5. Forewing densely covered with yellowish brown scales; male genitalia: caudal margin of basal lobes of uncus convex medially; ventral process of valva small, short, triangular ... C. deprinsi Park & Aarvik, sp. n.

- Forewing sparsely scattered with yellowish brown scales; caudal margin of basal lobes of uncus incised in V-shape medially; ventral process of valva slender, digitate ... C. kenyaensis Park & Aarvik, sp. n.

Corymbus deprinsi Park & Aarvik, sp. n. (Figs 1A, 2A-F)

Holotype: ♂, KENYA, Taita Hills, (K4), Yal plantation; 13-III-1999; U. Dall’Asta leg.; Hg+ Hal; gen. slide no. CIS-7133/Park; RMCA.

Paratypes: ♂; same data as holotype; wing slide no. CIS-7149/Park; 1 ♂; Taita Hills, (K4), Ngangao For. & Plantation; 6-VII-1998; U. Dall’Asta leg.; gen. slide no. CIS-7128/Park; RMCA.

Description Adult (Figs 2A, B): Male wingspan 15-17 mm. Head: Vertex covered with orange white scales. Antenna slightly longer than forewing; basal segment elongate, slightly dilated toward apex, orange white; flagellum orange white, filiform, not ciliate. Second segment of labial palpus with long, hair like orange white scales above; 3^rd segment shorter than 2^nd segment, strongly upturned, orange white to pale orange, pointed apically. Thorax orange white to pale orange; tegulae of same colour, with fuscous scales along anterior margin. Hind tibia densely haired, fuscous grey on outer surface. Forewing ground colour orange white, brownish scales scattered irregularly, more dense beneath costa and in distal region; a round fuscous discal spot in middle and a kidney shaped one near end of cell; costa slightly arched; apex more or less acute; termen oblique; venation (Fig. 1A) as described for the genus. Hindwing orange white; venation with M₂ absent; M₃ and CuA₁ stalked. Abdomen yellowish brown on dorsal surface; tergites lack spinose zones; segment VII with sclerotized ridge on anterior margin (Fig. 2F).

Male genitalia (Figs 2C-E): Basal lobes of uncus semi ovate, directed outwardly, convex medially on caudal margin. Gnathos with heavily sclerotized basal plate; median process slender, curved downward beyond middle. Costal bar banded, arising from base of tegumen and reaching middle of valva, without distinctly acute median angle. Valva broad in basal 1/4, then narrowed; costa deeply concave medially; cucullus elongate, more or less thumb like with round apex, densely setose, with broad scales along apical margin; a small, triangular process near lower corner of cucullus, followed by small pegs along ventral margin towards apex; sacculus broad, terminated with round apex, shorter than 1/2 the length of basal part of valva. Juxta weakly sclerotized; latero caudal process slender, directed outwardly, slightly shorter than length of juxta; anterior margin broadly convex. Vinculum broad, with round apices; outer margin sclerotized, banded. Aedeagus thick, as long as valva, curved medially, with pair of small triangular spines subapically on dorsal margin. Female unknown.

Diagnosis: The new species is similar to the following new species, C. malmoius but it can be distinguished by more oblique termen of the forewing, fringes concolourous with weak median brownish band. In C. malmoius, the fringes are dark brown in distal half; and the valva of the male genitalia has a small, sharply acute, triangular process apically near the lower corner on ventral margin of cucullus, whereas C. malmoius does not have such a sharply pointed triangular process, but has a rounded protrusion on the ventral margin.

Distribution: Kenya (Central).

Etymology: The species is named in honour of Willy De Prins who gave a remarkable contribution to studies on African moths, compiling the Afromoths website.

Corymbus malmoius Park & Aarvik, sp. n. (Figs 3A-G)

Holotype: ♂, TANZANIA, Arumeru Distr., Usa River; 1170 m; 1-VIII-1991; L. Aarvik leg; gen. slide no. CIS-7146/Park; NHMO.

Paratypes: 1 ♂, KENYA, Taita Hills, Wundanyi; 1350 m; 11-VII-1999; A. Bjørnstad leg.; gen. slide no. CIS-7171/Park, wing slide CIS-7253/Park; NHMO; 1 ♂, Eastern Prov., Lewa Conservancy; 2080 m; [UTM:] 37N CA 2838 1547; 28-30-XI-2008; L. Aarvik, D. Agassiz, A. Kingston leg.; gen. slide no. CIS-7145/Park; NHMO; 1 ♂, Taita Hills (C4), Ngangao mixed forest; 5-III-1999; U. Dall’Asta leg.; Hg+Hal; gen. slide no. CIS-7148/Park; RMCA; 1 ♂, Taita Hills (E4), Mbololo mixed for.; 7-III-1999;

U. Dall’Asta leg.; Hg+Hal; gen. slide no. CIS-7152/Park; RMCA.

Description Adult (Fig. 3A, B): Male wingspan 14-16 mm. Head, vertex orange white, with orange white,(comma not needed) erect scales laterally; frons orange white. Antenna longer than forewing; basal segment orange white, slightly dilated toward apex, without pecten; flagellum filiform, orange white throughout, not ciliate. Second segment of labial palpus densely covered with long, orange white hair like scales above, ventral surface more less smooth; 3^rd segment shorter than 2^nd segment, upturned, orange white, pointed apically. Thorax orange white; tegulae of same colour with fuscous scales along anterior margin. Hind tibia with dense hair like scales above and beneath, orange white mixed with grey scales. Forewing ground colour pale orange, densely and irregularly scattered with brownish scales, more dense in upper part of cell and distal 2/5; a distinct round, fuscous discal spot in middle and a kidney shaped one near end of cell; costa slightly arched in basal half and beyond 2/3; apex more or less acute; termen oblique, slightly sinuate medially; fringe shining white in basal 1/3, then black beyond; venation as C. deprinsi sp. n. Hindwing orange white; venation as in C. deprinsi sp. n. Abdomen yellowish brown on dorsal surface, lacking spinose zones on tergites; segment VII with sclerotized ridge on anterior margin. (Fig. 3G).

Male genitalia (Figs 3C-F): Basal lobes of uncus semiovate, directed outwardly, emarginated in Vshape medially on caudal margin. Gnathos with heavily sclerotized basal plate; median process slender, curved downward beyond 2/3. Tegumen posteriorly deeply emarginated in V-shape. Costal bar banded, curved downward at middle, not sharply angled medially. Valva extremely broad in basal 1/4, then abruptly narrowed; costa deeply concave medially; cucullus elongate, thumb like, densely setose, strongly convex on dorsal margin, with broad scales along apical margin; ventral margin with abroad protrusion at lower corner, followed by numerous pegs along margin towards apex; sacculus broad, terminated with round apex, about 1/4 length of ventral margin of valva. Juxta with slender latero caudal processes, shorter than the length of juxta; caudal margin concave medially and anterior margin medially with triangular process. Vinculum broad, rounded apically; outer margin narrowly sclerotized. Aedeagus stout, as long as valva, strongly curved medially, with pair of small triangular processes subapically on dorsal margin.