Erannis jacobsoni ( Djakonov, 1926 )

Beljaev, Evgeniy A., Vasilenko, Sergey V., Dubatolov, Vladimir V. & Zinchenko, Vadim K., 2024, First report on late autumn geometer moths (Lepidoptera: Geometridae) from Kunashir Island, Russia (Southern Kurils), Amurian Zoological Journal XVI (4), pp. 979-995 : 984-985

* Erannis jacobsoni ( Djakonov, 1926) ( Fig. 3 B )

Material. Kaldernyi Cordon, at light (near the morning), 31.10– 1.11.2023 – 1♂.

Distribution. Russia (Altai, Tyva, Irkutskaya Obl., Buryatia, RFE: Amur Obl., Jewish A.O., Khabarovsk Kr., Primorsky Kr., Sakhalin, S Kurils – Kunashir); E Kazakhstan, Mongolia, Northeast China, North Korea, Japan (Hokkaido, Honshu, Shikoku).

Remarks. This species, newly recorded for the Kuril Islands, is represented on Kunashir by the subspecies E. jacobsoni giganthea Inoue, 1955 , also found in Sakhalin and Japan. In Japan, the moths appear from late October to late November. In Hokkaido it is commonly found in large numbers in larch forests and is sometimes considered a pest ( Sato 2011). In the continental part of the RFE, moths are observed from late September to late October ( Beljaev 1996). The larvae feed on a variety of coniferous species ( Pinaceae ).

The status of the taxon giganthea has been subject to debate. Initially Inoue described it as a valid species. In the description he noted that it is "very close related to jacobsoni Djakonov from the Central Altai …, but larger in size and it appears in autumn while jacobsoni … wing in spring" ( Inoue 1955: 76). Later, gigantea was downgraded to a subspecies of Erannis defoliaria (Clerck, 1759) , based on the similarities in the appearance of moths and in the shape of the valva in the male genitalia ( Inoue 1982). This view has been widely accepted in Japanese literature and on the Internet sites ( Nakajima 1998; Niwakagamania et al. 2024). In contrast, Beljaev ( Beljaev 1996) proposed recognizing gigantea as a subspecies of Erannis jacobsoni ( Djakonov, 1926) , based on the almost complete similarity of the wing pattern and coloration with the Far Eastern subspecies Erannis jacobsoni sichotenaria Kurentzov, 1937 . This approach has been adopted in Russian literature, including taxonomic catalogs ( Mironov et al. 2008; Beljaev 2016; Beljaev, Mironov 2019). Nakajima ( Nakajima 2010) restored gigantea to the species rank, based on a comparison of the male genitalia of Japanese specimens with the European E. defoliaria only, without comparing them to E. jacobsoni . He questioned the Beljaev's decisions, citing the fact that he had not examined the type specimen of E. jacobsoni , and that moths of the later emerge in spring.

According to the original description, the type series of E. jacobsoni (described in ‡ Hibernia, a misspelling of Hybernia Berthold, 1827 ) consist of three males and one female. The holotype is not designated. The male genitalia of one syntype were depicted in the original description of the species ( Djakonov 1926), and the photo of the other male syntype was published later ( Djakonov 1929). These data confirm the identity of E. jacobsoni . However, the published collection date of the type specimens — 30 June 1898, which was one of the reasons for the misinterpretation of giganthea, — does not correspond to the real time of emerge of moths of E. jacobsoni , which occurs in autumn. Since The type series includes one male and one female, reared from larvae. Therefore, the date is likely to refer to the larvae collection date, which is quite real, and not the capture of adult moths.

A comparison of the male genitalia of E. jacobsoni jacobsoni from Altai ( Djakonov 1926) and Buryatia ( Beljaev 1996; Makhov 2021), E. jacobsoni sichotenaria from Primorsky Kr. ( Beljaev 1996) and North Korea ( Tóth 2017), and gigantea from Japan ( Nakajima 1998; Nakajima 2010) shows their structural similarities, making it impossible to distinguish morphologically the latter taxon as a separate species. Therefore, at this stage of research, it is most appropriate to retain the status of gigantea as a subspecies of E. jacobsoni .

The Online Taxonomic Facility of Geometridae ( Rajaei et al. 2022) recognizes the taxon E.jacobsoni gigantea , while the Global Biodiversity Information Facility lists it as both E. gigantea ( Erannis gigantea … 2024), and as E. jacobsoni subsp. gigantea ( Erannis jacobsoni … 2024).

Figures

Fig. 3. Geometrid moths (Geomtridae) from Kunashir Island: A — Erannis golda, male; B — Erannis jacobsoni, male; C — Alsophila inouei, male; D — Alsophila japonensis, male; E — Inurois asahinai, male; F — Inurois fumosa, male; G — Inurois punctigera, male; H — Operophtera brunnea, male; I — Operophtera relegata, male; J — Eupithecia scribai, female; K — Eupithecia daemionata, female. Scale bar: 10 mm