Exaeretia allisella Stainton, 1849

Arashima, Hazumu, Yagi, Sadahisa, Sasaki, Kimitaka, Suzuki, Shinya & Hirowatari, Toshiya, 2025, Two species of Depressariidae (Lepidoptera: Gelechioidea) newly recorded from the grassland of southwestern Japan, Zootaxa 5647 (6), pp. 584-594 : 586-588

Exaeretia allisella Stainton, 1849

(Japanese name: Suisei-hirata-maruha-kibaga).

( Figs. 2–3 )

Exaeretia allisella Stainton, 1849: 152 .

Depressaria lechriosema Meyrick, 1928: 475 .

Material examined. JAPAN, Kyushu: 1♂, Fukuoka, Kitakyushu-shi, Kokuraminami-ku, Hiraodai , 14. VI.2008, K. Sasaki leg. ; 2♂, same locality, 4.X.2019, K. Sasaki leg. , gen. slide. no. HA22-75, HA23-133; 2♂, same locality, 1.X.2023, S. Suzuki leg. ; 2♂, Nagasaki, Higashisonogi-cho, Onohara , 25.IX.2021, S. Tomura leg. , gen. slide. no. HA23-165, HA23-166; 1♂, Kumamoto, Aso-shi, Nishiyunoura , 30.VIII.2023, S. Suzuki leg. ; 6♂, Kumamoto, Aso-shi, Ichinomiya-machi, Sakanashi , 12.IX.2024, S. Suzuki leg. , gen. slide. no. HA24-248, HA24-249, HA24-250; 1♂, Kumamoto, Aso-shi, Nishiyunoura , 13.IX.2024, S. Suzuki leg.

Diagnosis. The forewing pattern of this species is difficult to distinguish from that of E. daurella Lvovsky, 1998 by sharing discal vein of forewing crossed by oblique black streak. The male genitalia of this species are similar to those of E. daurella by sharing the similar shape of socius, gnathos and cuiller, but it can be distinguished by the numerous and very small cornuti (in E. daurella , cornuti are absent).

Redescription. Male ( Fig. 2 ). Forewing length 7.3–9.1 mm (n = 15), wingspan 16.0– 19.3 mm (n = 15). Head dark brown. Antennae beige on upper surface. Labial palpus upturned, dark brown with some beige scales; third with pale yellow scales in the middle and apex. Thorax covered with brown and black scales. Legs dorsally pale yellow with some brown scales, ventrally brown with pale yellow scales. Forewing dark brown with some pale yellow, black, and purplish brown scales; two oblique dark brown stripes from costal margin to inner margin; fringe brown. Forewing underside dark beige; costal and outer margins dark brown scattered with pale yellow scales. Hindwing pale yellow, darker towards apex, costal margins and veins light brown, fringe pale yellow, rather darker near apex. Hindwing underside light beige, near costal margin scattered with many brownish scales. Abdomen pale yellow dorsally, brown ventrally with some light beige scales.

Male genitalia ( Fig. 3 ). Uncus small, distinct, overtopped by socius in standard preparation. Socius broadly elliptic. Gnathos rounded, globular. Transtilla of uniform width, wide, and almost straight. Transtilla lobes semielliptic. Valva broad at base, tapering to its tip, costal margin curving. Cuiller with two processes; upper process distinctly shorter and thinner in comparison with lower one; lower process curved downwardly. Juxta broad elliptic, posterior margin with pair of angular processes. Anellus lobes narrow, straight, apex rounded, towards tip of valva. Saccus tapered toward tip. Phallus ( Fig. 3B ) almost straight with curved tip. Vesica with numerous, minute cornuti.

DNA analysis. Partial COI sequences of one male specimen collected from Hiraodai, Fukuoka Prefecture., and one male specimen collected from Onohara, Nagasaki Prefecture, were uploaded to the BOLD systems in the dataset DS-HADP002 and their BIN ID was BOLD: ABA0482 . The sequenced data were deposited in GenBank with the accession numbers PV278027 and PV278028. The sequences of the specimens collected from the two sites in Kyushu matched completely. The uncorrected pairwise distances between the Japanese specimens and specimens collected in Europe , Russia, and China were 0.00–3.42% in the COI barcode region. The phylogenetic tree ( Fig. 4 ) showed four clades of E. allisella , and the Japanese specimens were included in one clade with specimens from Russia (Altai) and Switzerland. Japanese specimens had 5.71% pairwise distance from the most similar species, Exaeretia lvovskyi Buchner, Junnilainen, & Nupponen, 2019 (accession number MN942293 ) .

Distribution. Japan (Kyushu), new record; China, Mongolia, Russia, Ukraine, Ireland, Belgium, Germany,

Czechia, Slovakia, and Poland northward to Fennoscandia, Belarus, Estonia, Latvia, Lithuania, Switzerland, and the

Carpathians ( Lvovsky 2014; Buchner & Corley 2024). Host plant. Artemisia vulgaris , A. campestris ( Asteraceae ) ( Lvovsky 2014).

Remarks. The forewing pattern and male genitalia of the Japanese specimens matched those of E. allisella , featuring two oblique dark stripes in the forewing and the shape of the cuiller. However, they also matched those of E. liupanshana Wang, 2010 from China. This species is described as a separate species based on the shorter upper process of the cuiller and the longer signum plate in its genitalia. However, Buchner and Šumpich (2020) provisionally concluded that E. liupanshana should be synonymized with E. allisella because these differences fall within the intraspecific variability range based on the comparison of many specimens. The upper process of the cuiller in specimens collected from Japan is almost the same length as that of E. liupanshana , but the BLAST search showed that Japanese specimens completely matched European E. allisella . Therefore, we agree with the opinion of Buchner and Šumpich (2020), although we have not proposed a taxonomic change considering that we have not observed the type materials of E. liupanshana and did not compare the sequences of the specimens identified as E. liupanshana .

Japanese specimens have brown forewings with two oblique dark stripes which show individual variation ( Fig. 2 ), whereas typical European specimens are pale grey in the basal half and have a diffuse but distinct dark patch near the centre distally of the oblique dividing line. Such grey specimens have not been recorded from Japan yet. The phylogenetic tree did not show any relation between forewing color and the COI barcode. The tendency for darker color on the forewing of only the specimens collected from Kyushu is occasionally observed in other Depressariidae species, e.g. Agonopterix multiplicella (Erschoff, 1877) , A. asebiella Arashima, Yagi & Hirowatari, 2023 and A. costaemaculella (Christoph, 1882) (H. Arashima, pers. obs.). Further investigation, including analyzing other DNA regions and observation of specimens from neighboring areas, is needed to clarify the distribution range and environmental conditions or genetic basis for this tendency.

Figures

FIGURE. 2. Adults of Exaeretia allisella Stainton, 1849. A–C, male. Scale bars = 5 mm.

FIGURE. 3. Male genitalia of Exaeretia allisella Stainton, 1849, gen. slide no. HA24-249. A, whole genitalia except phallus; B, phallus. Scale bar = 0.5 mm.

FIGURE. 4. Neighbor-joining tree of Exaeretia allisella with comparatively close sequences and Agonopterix gibbosa as an example of an outgroup. The numbers near the nodes indicate Bootstrap support (%).