Mirlatia arcuata, Hausmann & László & Mayr & Huemer, 2023

Hausmann, Axel, Laszlo, Gyula M., Mayr, Toni & Huemer, Peter, 2023, Surprising discovery of an enigmatic geometrid in Croatia: Mirlatia arcuata, gen. nov., sp. nov. (Lepidoptera, Geometridae), ZooKeys 1183, pp. 99-110 : 99

Mirlatia arcuata sp. nov.

Type materials.

Holotype: male, "Podgora - Drvenik / YU [southern Croatia, 25 km SE Makarska] [leg. Robert] Hentscholek / [handwritten] 18.3.1983" // DNA barcode sample ID BC_ZSM_Lep_115293 // gen. prp. Hausm. G 22091 // coll. TLMF.

Paratype: 1 female, "Podgora - Drvenik / YU [southern Croatia, 25 km SE Makarska] [leg. Robert] Hentscholek / [hand written] 27.3.1982" // [gen. prp. nr. László] 3352 ♀ // coll. NHMV.

Description.

For structural external morphology of adults, see the genus description.

Male (Fig. 1 ). Wingspan: 27 mm. Colouration. Frons brown, vertex whitish. Ground colour of wings whitish, slightly irrorated by brown scales (holotype apparently in a slightly worn state); wing pattern very diffuse, undulate antemedial line and postmedial line marked by brown scales, hardly visible. Ante- and postmedial lines more sharply marked at forewing costa and at inner termen of fore- and hindwing. Discal spots absent on all wings. Fringe concolorous with ground colour.

Male genitalia (Fig. 3 ). Uncus broadly dilated, spoon-shaped, covered by sparse, long hairs; gnathos absent; juxta with rugose and posteriorly spinulose membrane; saccus short, angular with rounded corners; valva broad, dorsal margin gently concave, ventral margin convex with a short rounded subbasal projection, apex broadly rounded, valva plate largely membranous with narrow costal sclerotization without appendages. Aedeagus stalked in the basal half, abruptly broadened in the distal half; uneverted vesica with fine spinules anteriorly and a large field of aciculate cornuti posteriorly. Sternum A8 and tergum A8 membranous, simple, without appendages.

Female (Fig. 2 ). Wingspan: 29 mm. Colouration. Frons brown, vertex whitish. Ground colour of wings whitish, heavily irrorated by brown scales; wing pattern diffuse, undulate antemedial line, dentate postmedial line and a few dark brown dots in terminal area vaguely visible on forewing; ante- and postmedial lines more strongly marked at costa and inner termen. On hindwing, dentate medial and postmedial lines more contrasting towards inner termen. Discal spots absent on all wings. Terminal line brown, indistinct. Fringe concolorous with ground colour.

Female genitalia (Fig. 5 ). Papilla analis broad, evenly rounded, finely setose. Posterior apophysis twice as long as anterior apophysis, the latter ones interconnected by a narrow, strongly sclerotized, evenly arched band. Ostium bursae membranous, corrugated, rather broad. Ductus bursae strongly sclerotized, very short and broad, twice as wide as long. Corpus bursae oval, strongly sclerotized in posterior third, with longitudinal striation towards ductus bursae. One strongly contrasting, elongate structure in the corpus bursae likely referring to remnant of a spermatophore.

Genetic data.

The male holotype has been successfully sequenced to a 658-bp fragment containing an internal 200-bp gap. Nearest neighbor: Idaea muricata at a distance of 7.8% in the BOLD barcode-gap analysis, with several next-nearest species at distances of 7.8-8.0% from various families such as Gelechiidae , Blastobasidae , Erebidae , and Euteliidae . Chimera status excluded by examination of both subfragments: Subfragment 1 (3') with nearest neighbor from genus Adoxophyes ( Tortricidae : 6.37%) and several geometrids (all subfamilies) at distances of 6.8-7.0%. Subfragment 2 (5') with nearest neighbor from genus Ergavia ( Sterrhinae : 5.95%) and several Lepidoptera from other families (e.g. Erebidae ) at distances of ~6.2%. Hence, there is no evidence for contamination in both fragments and, therefore, no evidence for a chimera sequence. Nevertheless, from a genetic point of view, our fragmented COI sequence does not allow for a clear assignation of the new genus to any geometrid subfamily, tribe, or genus.

Differential diagnosis.

The distinctive features of the new species are discussed under the differential diagnosis of the genus.

Etymology.

The species name refers to the arcuate hindwing termen.

Ecology, phenology.

The type series was collected in southern Croatia at Drvenik (25 km SE of Makarska) from mid- to late March, close to the Mediterranean shoreline, in a habitat dominated by steep limestone rocks and scree (Fig. 7 ). The worn stage of the holotype indicates that the main flight period might be earlier, i.e. in late winter, and even a hibernation in the adult stage cannot be ruled out. The whitish ground colour of the adults may indicate a possible camouflaging and resting habit among light rocks characteristic at the type locality.

Figures

Figure 1. Adult. Mirlatia arcuata sp. nov., holotype, male (coll. TLMF).

Figure 2. Adult. Mirlatia arcuata sp. nov., paratype, female (coll. NHMV).

Figure 3. Male genitalia. Mirlatia arcuata sp. nov., holotype, slide No.: G 22091 (prep. A. Hausmann, coll. TLMF). Scale bar: 1 mm.

Figure 5. Female genitalia. Mirlatia arcuata sp. nov., paratype slide No.: LG 3352 (prep. G. Laszlo, coll. NHMV). Scale bar: 1 mm.

Figure 7. Habitat of Mirlatia arcuata sp. nov., Croatia, Podgora (photograph S. Gomboc).