Metaeuchromius micralis Léger 2024, comb nov.
Creators: name: Léger, Théo
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Lepidoptera
Crambidae
Metaeuchromius
Metaeuchromius micralis

description: Metaeuchromius micralis (Hampson, 1919) comb nov.
Figs. 51, 115, 173.
Ommatopteryx micralis Hampson, 1919 a: 535. Type locality: Philippines, Luzon, Benguet Prov., Irizan
= Euchromius brunnealis syn. nov (Hampson, 1919). Type locality: Philippines, Negros island
MATERIAL
Material examined: 33 ♂, 27 ♀, 7 unsexed (detailed information in Table S1; https://doi.org/10.5061/ dryad.b8gtht7mh).
SIMILAR SPECIES
Metaeuchromius fulvusalis Song & Chen, 2002, M. rizali sp. n., M. makintabus sp. n.
DIAGNOSIS
This species (Fig. 51) is very similar to Metaeuchromius fulvusalis from mainland China. In male genitalia (Fig. 115), the valva spine is less prominent than in M. fulvusalis, and the narrow colliculum of the female genitalia (Fig. 173) is absent in M. fulvusalis. In the Philippines, this species can be separated from M. rizali sp. n. and M. makintabus sp. n. by the subapical zigzag silver line on the forewing. In male genitalia, the short costal process of the valva as well as the vesical devoid of cornuti unambiguously separate this species from other Metaeuchromius species. In female genitalia, the narrow sclerotized colliculum, the short ductus bursae, and the presence of one rounded signum on corpus bursae best separate this species from M. makintabus sp. n. (female of M. rizali sp. n. is not known). DNA barcodes suggest that this species might indeed represent a complex of cryptic species.
REDESCRIPTION
HABITUS (FIG. 51)
Forewing length 4.5-6.5 mm (n = 16); ground color cream suffused with tawny scales. Basal area amber yellow, with one slender shiny silver streak along costal cell vein; three white streaks following lower cell vein and anal veins. Medial line oblique, running inwardly from costa to dorsum, white, shiny silver near costa, marked basally and distally with amber to tawny yellow. Subapical line starting at costal 3/4, zizagging outwardly to vein M1, shiny silver. Apex with subapical white lunule. Termen with five black points surrounded by white. Fringe amber yellow to copper. Hindwing dirty white, with faint patch of marginal brown scales at CuA2. Fringe dirty white, apically copper.
MALE GENITALIA (FIG. 115)
Uncus ca half of tegumen arm length, slightly bent downwards, apical 1/3 with few setae, apex thorn-shaped. Gnathos projection about 1/5 of uncus length, dorsally covered with tiny teeth, tip pointed. Valva elongate, setose; costal arm projected into a tip pointed upwards inwardly; ventral margin straight, apically curved upwards; apex pointed, with patch of 3-5 long, thick bristles. Juxta elliptical. Saccus rounded. Vesica covered with minute spines.
FEMALE GENITALIA (FIG. 173)
Papillae anales not coalesced dorsally and ventrally. Posterior apophyses about 7/4 of length of tergite VIII. Anterior apophyses about 9/5 of tergite length. Antrum membranous. Colliculum narrow, tubular, sclerotized. Ductus bursae about as long as corpus bursae, basal half narrow, enlarging towards corpus bursae on distal half. Corpus bursae with opening barely marked; ovoid, with one conspicuous signum.
DNA BARCODING
An unsuspected high divergence is observed among specimens of Metaeuchromius micralis. The species delimitation analysis recovered five different island-specific clusters for Luzon, Mindanao, Mindoro, Leyte + Samar, and Negros (Fig. 179c). The highest intraspecific p-distance of 7.3% is observed between samples MFNLEP-PYRALPHIL07-D11 from Leyte and MFNLEP-PYRALPHIL10-E11 from Negros.
DISTRIBUTION
PHILIPPINES: Leyte, Luzon, Mindanao, Mindoro, Negros. Collected at altitudes between 150 and 2300 m.
REMARKS
The type of “ Euchromius ” brunnealis (Hampson, 1919) could not be located at the NHMUK (D. Lees, personal communication). According to the original description, it matches the characters observed here in Metaeuchromius micralis: The forewing is “red-brown with a cupreous gloss and mixed with some whitish especially before and beyond the inwardly oblique rather ill-defined narrow red-brown medial band” and bears at the apex “an oblique ill-defined whitish band” similar to that of Metaeuchromius micralis, while the band is silver colored, straight in M. makintabus sp. n. or regularly arched in M. rizali sp. n. This species shows a strong divergence in DNA barcodes among island populations. No striking differences were found in male genitalia; however, forewing pattern and size show some island-specific variation. This species might represent a species complex whose investigation requires additional evidence such as nuclear markers and morphometric analyses.
description: Published as part of Léger, Théo, 2024, Half of the Diversity Undescribed: Integrative Taxonomy Reveals 32 New Species and a High Cryptic Diversity in the Scopariinae and Crambinae of the Philippines (Lepidoptera: Crambidae), pp. 1-93 in Bulletin of the Society of Systematic Biologists 3 (2) on pages 69-70, DOI: 10.18061/bssb.v3i2.9527, http://zenodo.org/record/15116964