Eulechria deltacostamela Lower, 1896: 165.

= Eulechria piodes Meyrick, 1902: 148, synonymized by Turner (1935).

= Eulechria deltomela Meyrick, 1922: 72, synonymized by Gaede (1938).

Queensland (Australia).

Commonwealth Scientific and Industrial Research Organization (CSIRO).

The genus Elaeonoma Meyrick, 1914 (Gelechioidea: Oecophoridae) is characterised by a very short proboscis, stalked veins CuA1 and CuA2 of the forewing, lack of the distal process of the sacculus of the male genitalia, short apophysis posterior, very short ductus bursae, and small membranous corpus bursae of the female genitalia (Common 2000). This genus is placed in the Barea genus group and is related to Baioglossa Common, 2000 and Eremnozona Common, 2000 (Common 2000), but is distinguished by having developed gnathos and a relatively short cornutus of the male genitalia. The biology of Elaeonoma is poorly understood; however, some adults have been collected using light traps, and E. swezeyi has been reared on dead plant of Barleria sp. (Acanthaceae) (Clarke 1984; Common 2000).

Turner (1916) described two new species from Australia, and Turner (1918) described a new species from Lord Howe Island near the Australian Continent. Meyrick (1922) listed 12 species from Australia (8 spp.), Ceylon (2 spp.), and New Guinea (2 spp.) with some generic transfers. Turner (1935) reviewed the Australian species (including Tasmania Island) of this genus and listed 28 species, including 17 new species. Turner (1935) synonymized Elaeonoma piodes with Eulechria deltacostamela Lower, 1896, without any morphological evidence. Gaede (1938) listed 31 species in this genus. Bradley (1956) described one new species from Lord Howe Island. Clarke (1963) illustrated and described the venation of the right wing, markings of the left wing, and genitalia of the type specimens of three species, E. piodes (= E. deltacostamela), E. autogramma, and E. nephelissa. Clarke (1984) described three new species, E. adeneia, E. moira, and E. swezeyi from the Micronesian Islands. However, Common (2000) recognized that all Ceylonese and New Guinean species were misplaced in the genus Elaeonoma. Additionally, based on the genital morphological characteristics, Common (1997) and Common (2000) treated all Australian species as other genera or incertae sedis except the type species, E. deltacostamela. However, the three Micronesian species were not mentioned in either study.

munin-hagane-maruha-kibaga.

Elaeonoma ultima sp. nov. is distinguished from other Elaeonoma species sensuClarke (1984) and Common (2000) by the following characteristics: in the forewing, the cuneiform dark spot extending from 1/2 of the costal margin is absent; the ground colour is not entirely blackish brown; in the cell, the plical spot is present and is located at approximately the same level as the discal spot, but never basal to it. Male genitalia are similar to those of E. swezeyi with an pointed triangular uncus and a narrow dorsal and ventral apex of the valva. However, E. ultima sp. nov. is distinguished by the dorsal margin of the valva, which is convex at 2/3 of the costal margin (nearly straight to slightly concave in E. swezeyi). The female genitalia are similar to those of E. swezeyi with a long apophysis posterioris and lacking a signum. However, E. ultima sp. nov. is distinguished by its small weakly sclerotized lamella postvaginalis (strongly sclerotized plate in E. swezeyi).

Adult (Figs 1, 2, 3). Sexual dimorphism. Forewing length male 4.4–7.3 mm (n = 28; holotype: 5.0 mm), female 4.7–9.4 mm (n = 17). Wingspan male 9.6–16.0 mm (n = 28; holotype: 11.2 mm), female 10.8–21.0 mm (n = 17).

Male (Fig. 1A, C). Head: Frons and vertex yellowish brown tinged with dark brown. Labial palpus with second palpomere dark brown tinged with yellowish brown outer surface, yellowish brown inner surface; third palpomere dark brown tinged with yellowish brown. Antenna with scape yellowish brown ventrally; flagellomere dark brown; bipectinate trichoid sensillum, twice length of flagellomere. Proboscis very short.

Thorax: Fuscous with dark brown with yellowish brown scales dorsally. Tegula greyish brown. Fore and mid coxa to tibia dark brown with cream at middle and apically; fore- and mid-tarsomere dark brown basally and dorsally, cream ventroapically. Hind coxa to hind tibia dark brown tinged with cream; hind-tarsomere dark brown basally and dorsally, cream ventroapically. Forewing (Figs 1A, 3) lanceolate, ground color dark brown, tinged with yellowish brown; base to basal 2/5 yellowish brown tinged with dark brown; basal 2/5 dark brown band from costa to dorsum; discal and plical oval spots dark brown at basal 2/5; discocellular oval spot at basal 2/3; terminal dots dark brown along termen. Forewing venation with Sc, R1–3, R4+5, M1–3, CuA1–2, CuP and 1A+2A present; R1 from basal 2/3 of discal cell to basal 5/7 of costa; R4+R5 stalked from basal 1/2; R5 reached to apex; CuA1 and CuA2 not stalked; 1A+2A fused from basal 1/3 to end. Hindwing (Figs 1A, 3) dark brown, basal 1/3 greyish brown; fringe greyish brown. Hindwing venation with Sc, Rs, M1–3, CuA1–2, CuP, 1A+2A and 3A present; frenulum a single slender bristle.

Abdomen (Fig. 4A, B): Apodeme very short. Venula straight. Tergum deciduous spines present.

Genitalia (Fig. 5A, B): Symmetrical. Uncus triangular, apex acute and pointed. Gnathos fused, beak-shaped, twice length of uncus with denticulate protrusions dorsally; apex pointed with falcate acute projection. Tegumen trapezoidal, broad medially, lateral arm narrowed to blunt apex. Valva trapezoidal, parallel to basal 2/3, narrowed at apical 1/3; costa straight with setae; apex attenuate and blunt; sacculus slightly narrowed apically with setae; fusiform appendages from ventrobasal part of valva to middle costa, appendages slightly wrinkled and setose. Saccus semicircular, strongly sclerotized, 2/3 as long as uncus. Juxta rectangular, plate-like, sclerotized, bilobed basally, as long as uncus. Phallus sclerotized, 3/4 as long as valva, curved ventrally, widen to base; cornutus straight spine, 2/3 as long as phallus.

Female (Fig. 1B, D). Head: Frons and vertex greyish yellow tinged with brown. Labial palpus with second palpomere dark brown, tinged with cream outer surface, cream inner surface; third palpomere cream, tinged with dark brown. Antenna with scape greyish yellow, tinged with dark brown ventrally; flagellomere greyish yellow; sensillum very short. Proboscis very short.

Thorax: Fuscous with greyish yellow, with greyish brown scales dorsally. Tegula greyish brown. Fore and mid coxa to tibia dark brown with cream at middle and apically; fore- and mid-tarsomere dark brown basally and dorsally, cream ventroapically. Hind coxa to hind tibia cream tinged with dark brown; hind-tarsomere light brown basally and dorsally, cream ventroapically. Forewing (Fig. 1B) lanceolate, ground color greyish yellow, tinged with dark brown; base to basal 2/5 greyish yellow tinged with dark brown, costa dark brown; at basal 2/5 wide, dark brown band from costa to dorsum; discal and plical oval spots dark brown, distinct at basal 2/5; discocellular oval spot at basal 2/3; terminal dots dark brown along termen. Hindwing (Fig. 1B) greyish brown, basal 1/3 whitish brown; fringe greyish brown.

Abdomen (Fig. 4C, D): Apodeme straight, slightly shorter than venula. Venula straight. Tergum deciduous spines present.

Genitalia (Fig. 5C, D): Papilla analis setose, elongated, rounded on posterior margin. Apophyses anteriores 5/8 length of apophyses posteriores. Eighth tergum sclerotized, trapezoidal, narrowed posteriorly, anterior middle convex, baculiform process elongated. Ostium bursae membranous. Antrum conical, short, narrowed anteriorly. Ductus seminalis elongated from anterior end of antrum. Ductus bursae membranous, slender, 2/3 length of apophyses posteriores, slightly widened to corpus bursae. Corpus bursae ovate, membranous, poorly developed, and small. Signum absent.

Variation: Slight and consistent differences were observed between the Chichijima (type locality) and Hahajima populations; these are treated as intraspecific variation and summarised below.

Male (Figs 1C, 4B, 5B). Forewing ground colour is often entirely dark brown in Hahajima populations. The abdominal apodeme of Hahajima populations is slightly longer than that of Chichijima populations. In the genitalia, the uncus of Hahajima populations is more obtuse triangular and wider at base than that of Chichijima populations; the attenuate apex of valva of Hahajima populations is slightly more elongated than that of Chichijima populations.

Female (Figs 1D, 4D, 5D). The costal base to basal 1/3 of forewing is often dark brown in Hahajima populations. The abdominal apodeme of Hahajima populations is slightly curved apically. In the genitalia, the anterior middle of eighth tergum is widened at base.

Holotype. • ♂; [JPN: Tokyo-Pref.] Shigureyama, Chichijima-Is., Ogasawara-mura; 27.0629°N, 142.2214°E; alt. 252 m; 26.VI.2022; LT; S. Tomura leg.; specimens no. and sample ID for DNA analysis: ST580; deposited in ELKU.

Paratypes. [Chichijima Island] • 1♀, same locality, date, method and collector; specimens no. and sample ID: ST583; ELKU•1♀, same locality, date and method; S. Yagi, S. Tomura, M. Kimura leg.; ELKU•1♂3♀, same locality and method; 18.VI.2022; S. Tomura leg.; specimens no. and sample ID: ST678, ST679; ELKU•1♂, same locality date and method; T. Hirowatari, S. Yagi, S. Tomura, I. Ohshima, M. Kimura leg.; specimens no.: ST796; ELKU•2♂, same locality and method; 11.VI.2023; S. Yagi leg.; specimens no. ST726; ELKU•1♀, same locality, method and date; T. Hirowatari, S. Yagi, Y. Matsui, J.-H. Park, I. Kawashima, J. Hamaguchi, M. Kimura leg.; specimens no. and sample ID: ST758•1♂, Asahiyama, Ogasawara-mura; 27.0954°N, 142.2135°E; alt. 206 m; 26.VI.2022; SW; S. Tomura leg.; specimens no. and sample ID: ST677; ELKU•2♂, same locality and method; 18.VI.2022; S. Yagi leg.; specimens no. ST782; ELKU•2♂, same locality, date and method; T. Hirowatari leg.; specimens no. ST780; ELKU•1♀, Higashidaira, Ogasawara-mura; 27.0749°N, 142.2216°E; alt. 235 m; 18.VI.2022; S. Tomura leg.; specimens no. ST588; ELKU•1♂, same locality, date and method; T. Hirowatari leg.; specimens no. and sample ID: ST676; ELKU•1♂, same locality and method; 27.0739°N, 142.2223°E; alt. 239 m; 26.VI.2022; S. Tomura leg.; specimens no. ST586; ELKU•3♂, Mt. Chûô-san, Ogasawara Vill.; 19.VI.2023; SW; J.-H. Park leg.; specimens no. and sample ID: ST781; ELKU•3♂3♀, Kuwanokiyama, Ogasawara-mura; 27.0777°N, 142.2174°E; alt. 216 m; 19.VI.2022; LT; S. Tomura leg.; specimens no. and sample ID: ST582, ST587, ST675, ST795; ELKU•1♀, same locality, date and method; S. Yagi leg.; specimens no. ST779; ELKU.

Other materials. [Hahajima Island]•1♀, Sakaigatake, Ogasawara-mura; 26.6705°N, 142.1559°E; alt. 411 m; 22.VI.2022; S. Tomura leg.; specimens no. ST674; ELKU•1♂, same locality, 26.671°N, 142.155°E; 15.VII.2024; flying just after sunset; Y. Matsui leg.; ELKU•1♂, Kuwanokiyama; 26.6632°N, 142.1530°E; 13.VI.2025; LT; S. Yagi leg.; specimens no. and sample ID: ST784; ELKU•1♂, Mt. Chôki-yama, Ogasawara-mura; 26.6509°N, 142.1568°E; alt. 200 m; 15.VI.2023; LT; S. Yagi leg.; ELKU•1♀, same locality, date and method; Y. Matsui leg.; specimens no. and sample ID: ST786; ELKU•2♂, same locality, date and method; T. Hirowatari, S. Yagi, Y. Matsui, J-H. Park, I. Kawashima, J. Hamaguchi, M. Kimura leg.; ELKU•1♂, Funakiyama, Ogasawara-mura; 26.6511°N, 142.1692°E; alt. 271 m; 24.VI.2022; S. Tomura leg.; specimens no. and sample ID: ST581; ELKU•1♂, Funamidai, Ogasawara-mura; 21.VI.2022; S. Tomura leg.; specimens no.: ST673; ELKU•4♀, Nishiura; 26.6557°N, 142.1531°E; 10.VI.2025; LT; S. Yagi leg.; specimens no. and sample ID: ST785; ELKU•1♂, same locality, method and collector; 15.VI.2025; specimens no. and sample ID: ST783; ELKU•1♂, Minamizaki; 26.62°N, 142.18°E; 21.IX.2023; daytime search; Y. Matsui leg.; specimens no. ST757; ELKU.

(Figs 6, 7) Adults of the new species were collected in June, July, and September, but not in March; therefore, this species is presumed to be uni- or bivoltine. During the day, adults were often collected by sweeping around mossed barks and bases of trees in the shade. At night, adults were collected using a light trap in the forest. When the collected adults were provided with cotton wool soaked in sugar water, they sucked the water by leaning forward and pressing their short proboscis against the surface. When the collected female adults were placed in a plastic case with dead leaves and bark covered with moss, they laid eggs in gaps between the bark and endemic moss, Leucobryum boninense Sull. & Lesq. Approximately two weeks later, the larvae hatched, spun thread and built a rough nest. A small amount of feces was also found, suggesting that this species feeds on moss and bark.

(Fig. 8) Japan: Ogasawara Islands (Chichijima and Hahajima Islands).

(Figs 9, 10, Table 1, Suppl. material 1) The DNA barcode sequences are deposited in the GenBank database under the accession numbers listed in Table 1 and uploaded to the BOLD system in the public dataset DS-OGAELAEO. The intra-island p-distances of E. ultima sp. nov. on Chichijima Is. are 0–3.33% (n = 11), those on Hahajima Is. are 0–2.48% (n = 6), and inter-island p-distances of E. ultima sp. nov. between the two islands are 4.29–6.03% (n = 17).

The DNA barcode of E. ultima sp. nov. (Sample ID: ST673) is closest to that of E. adeneia (BIN, BOLD:ADZ8644, Sample ID: CCDB-30823-C06, Process ID: LNAUW4108-18), according to the BOLD identification engine, with 8.73% pairwise divergence.

According to the phylogenetic tree constructed based on the COI barcode region, E. ultima was recovered as sister to E. adeneia, although the bootstrap support value was low (59%). The Chichijima population of E. ultima sp. nov. formed a monophyletic clade (bootstrap value = 84%). In contrast, the Hahajima specimens were not monophyletic and appeared as two lineages outside the Chichijima clade. According to the haplotype network constructed based on the COI barcode region, the Chichijima population of E. ultima is clearly separated from that of the Hahajima population. An association between the collection site and haplotypes within each island was not clearly observed.

The species epithet ultima is derived from the Latin word “ultimus” meaning “furthest.” This name reflects that the type locality of the Ogasawara Islands, which are located at the eastern end of Japan and are the outermost limit of the known distribution range of this genus.

Kato (1992) recorded two species of “Oecophoridae gen. sp.” from Chichijima and Anijima Islands. However, these were the unidentified species of the family Stathmopodidae (Kato, personal communication). It is presumed that this is due to the historical taxonomic treatments in which stathmopodid moths were regarded as a subfamily “Stathmopodinae” within Oecophoridae until recent years (e.g., Hodges 1998; Wang 2006). Recently, Stathmopodidae is clearly distinguished from Oecophoridae based on the morphological characteristics and molecular phylogenetic analysis (Heikkilä et al. 2014). According to the current classification, this study is the first confirmed record of the Oecophoridae from the Ogasawara Islands. Clarke (1984) mentioned that the Syûti Issiki’s specimen collection of the Smithsonian Museum contains some Gelechioidea of northern Micronesian Islands, but specimens and associated data from the Bonin (= Ogasawara) Islands were not confirmed.

Common (1997, 2000) treated most Australian Elaeonoma species as incertae sedis or the following other genera: Barea Walker, 1864, Chezala Walker, 1864, Diaphanta Common, 2000, Eulechria Meyrick, 1883, Ioptera Common, 1997, Ischnomorpha Common, 1996, Leimmatonca Common, 2000, Leipochlida Common, 2000, Micramicta Common, 2000, Neosigala Common, 2000, Orescoa Turner, 1927, Stenoptena Common, 2000, and Tanycaula Common, 1997. This new species is distinguished from these genera by the following morphological characteristics: short proboscis; bifid scale-crests on the thorax and forewing are absent; the forewing is not narrowly elongated and veins CuA1 and CuA2 are not strongly curved; the uncus is defined and rostral; the gnathos is not deeply concave dorsally, not strongly sclerotized, and does not have an inflated apex; the apex of the valva does not have a curved projection; the sacculus does not have an up-curved process and apex does not have a sclerotized distal process; apophysis posterior is not extremely long; and ductus bursae is not sclerotized.