The subgenus Brevantennia, originally described by Sieder in 1953, comprises ten species of small psychid moths distributed across south-west and south-east Europe, extending northwards to the Alps and Carpathians. Prior to this revision, the presence of three species in Slovenia was recorded in the literature: Dahlica adriatica, Dahlica triglavensis, and Dahlica styriaca. However, the difficulty in accurately identifying specimens had led to numerous errors in both the scientific literature and public genetic databases. The current study confirms the presence of D. adriatica and D. triglavensis in Slovenia while excluding D. styriaca from the national checklist, a decision supported by the absence of verifiable specimens and the misattribution of historical records.

A major taxonomic outcome of the research is the establishment of Dahlica santicensis as a valid, distinct species. Previously, this taxon had been synonymized with D. styriaca by Arnscheid in 1988, a conclusion based on a lack of significant morphological differences observed at the time. The current authors demonstrate that D. santicensis is clearly separated from Styrian populations through both molecular and morphological evidence. Furthermore, the species Dahlica gorskikotarica, described by Weidlich in 2015 from Croatia, is synonymized with D. santicensis. This synonymy is supported by DNA barcoding data showing that specimens from the type locality of D. gorskikotarica fall within the same Barcode Index Number (BIN) as D. santicensis, alongside morphological similarities in forewing coloration and genital indices.

The identification of these species relies heavily on the genital index, a morphometric ratio calculated by dividing the length of the phallus by the length of the valva in male genitalia. This index, introduced by Sauter in 1956, proved to be the most useful diagnostic tool in the study, particularly when combined with the shape of the cloaking scales on the forewings. The researchers found that wing venation, previously used for classification, is an unreliable character at the species level due to high variability within populations. In contrast, the genital index provided consistent values that allowed for the clear differentiation of D. santicensis from other narrow-scaled species such as D. triglavensis and D. siederi, which share similar scale classes but differ in specific index ranges and wing patterns.

Field studies across four regions of Slovenia, including Gorenjska, Štajerska, Notranjska, and Dolenjska, revealed that D. santicensis is more widespread and adaptable than previously thought. The species was found in 22 localities, ranging from lowland valleys at 392 meters to subalpine slopes at 1600 meters. Unlike its close relative D. siederi, which prefers sunny subalpine cliffs above the tree line, D. santicensis inhabits shaded, humid areas of mixed forests dominated by conifers such as Pinus sylvestris and Picea abies. This eurytopic nature allows the species to thrive in diverse microclimates, from cold creek valleys to forest edges, provided the substrate consists of limestone or volcanic rock where larval cases can be securely attached.

Biological observations indicate that D. santicensis is univoltine, with adults emerging from late March to early May. Males become active in the early morning, shortly after females emerge, engaging in mating behaviors that can last up to ten minutes. The larvae construct small, rounded cases from finely chewed bark, soil, and sand, which they attach to tree trunks, rocks, or wooden structures. The study also documented the co-occurrence of D. santicensis with several other bagworm species, including Dahlica triquetrella and Taleporia tubulosa, highlighting the complex community structure of these microhabitats. The high genetic variability within D. santicensis, with a maximum intraspecific distance of 2.57 percent, suggests a dynamic population structure that may warrant further investigation into potential cryptic diversity.

In contrast, Dahlica triglavensis is a montane-alpine species restricted to rocky habitats in the Julian Alps and Karavanke mountains. The study revealed two distinct genetic lineages within this species, separated by the Sava valley, with one lineage in the Julian Alps and the other in the Karavanke. Despite this genetic divergence, no morphological differences were found between the populations, leading the authors to retain the single species name. D. triglavensis exhibits a mixed voltinism strategy, with some populations showing semivoltine behavior, likely a two-year cycle, which helps them persist in harsh alpine environments. Adults emerge after snowmelt, typically from June to July, and are active in the morning when the rocky slopes are illuminated by the first sunlight.

Dahlica adriatica, the third species confirmed in Slovenia, is distributed in the Dinaric Alps, with Slovenia marking the northern limit of its range. The species is well-represented in humid biotopes, including sunny, mossy rocks in cold valleys and Illyric Ostryo-Quercetum forest communities. The study updated the genital index values for D. adriatica, finding them slightly higher than previously reported, ranging from 0.61 to 0.68. The presence of D. adriatica in Slovenia has been confirmed since 1919, but its status was uncertain for decades due to misidentifications. The current research solidifies its place in the Slovenian fauna, providing detailed records of its habitat preferences and phenology.

The exclusion of Dahlica styriaca from the Slovenian checklist is a significant correction to the national lepidoptera fauna. Historical references to the species in Slovenia were traced back to a single source from 1992, with no verifiable locality or specimen material. Field visits to the suspected locality confirmed the presence of D. santicensis instead. D. styriaca is currently known only from specific localities in Austria, particularly in the Steiermark region. The distinction between D. styriaca and D. santicensis is now clear, with D. styriaca exhibiting a higher genital index and different distribution patterns. This clarification removes a long-standing error in the literature and provides a more accurate picture of the regional biodiversity.

This revision underscores the importance of integrating molecular tools with traditional morphological analysis in the taxonomy of difficult insect groups. The use of DNA barcoding helped resolve ambiguities that could not be addressed by morphology alone, particularly in the case of D. gorskikotarica and the genetic lineages of D. triglavensis. The study also highlights the value of comprehensive fieldwork in understanding the ecology and distribution of these species. By providing updated diagnostic keys and detailed descriptions, the research offers a reliable resource for future entomological studies in the region, ensuring that accurate identification can be achieved through a combination of genetic and morphological data.

Subject of Research: Systematics of Slovenian Dahlica Enderlein, 1912, subgenus Brevantennia Sieder, 1953 (Lepidoptera, Psychidae)

Article Title: Systematics of Slovenian Dahlica Enderlein, 1912, subgenus Brevantennia Sieder, 1953 ( Lepidoptera , Psychidae )

Article References: Rekelj, J., Predovnik, Ž., Huemer, P., & Lopez-Vaamonde, C. (2022). Systematics of Slovenian Dahlica Enderlein, 1912, subgenus Brevantennia Sieder, 1953 (Lepidoptera, Psychidae). Nota Lepidopterologica, 45, 207-232. https://doi.org/10.3897/nl.45.81674

Image Credits: AI Generated

DOI: 10.3897/nl.45.81674

Keywords: Systematics, Slovenian, Dahlica, Enderlein, subgenus, Brevantennia, Sieder, Lepidoptera, Psychidae, scientific research