Barthelius pumilus, Mey, 2025

Mey, Wolfram, 2025, First records of species of Gelechioidae from Bitterfeld amber (Insecta, Lepidoptera) and notes on two gelechioid species from Baltic amber, Zitteliana 99, pp. 63-73 : 63-73

Barthelius pumilus sp. nov.

Figs 1–4 , 5–8 , 9

Type.

Holotype • ♂, Bitterfeld amber, Serie 11, 1987, Museum für Naturkunde, Berlin, inventory number: MB.I.17.488 ; Paratype • ♂, coll. Goitzsche Bernstein GmbH, inventory number: T-I-SM-43 .

Etymology.

The name is derived from the Latin “pumilus”, minute, referring to the tiny size of the species.

Preservation.

The individual is nearly completely preserved except missing left hindleg and tip of right antenna. Left fore- and hindwings are overlapping, right wings partly overlapping. Ventral side of head and abdomen sufficiently visible. From the male genitalia only the terminal part of uncus is visible. The small amber piece with the inclusion is embedded in a block of polyester resin (Figs 1 , 2 ).

Description.

Imago, male (Figs 1 – 9 ): Small adult moth with 2.25 mm wing length, and 2.1 mm body length wing expanse approximately 5.0 mm. Wings densely covered by scales not forming a pattern.

Head in ventro-frontal view (Fig. 3 ) with vertically enlarged vertex covered by appressed, laminate, shining scales, appressed scales also on frons; eyes small, in ventro-lateral position, interocular index 0.3; ocelli and chaetosema absent; antenna filiform, weakly scaled, about half the length of forewing, scape and pedicel each longer than following segments, 18 flagellomeres present, somewhat longer than wide (Fig. 5 ); anterior tentorial pits large. Mandibles, pilifers and maxillary palpi not visible (probably vestigial), proboscis long, two to three times as long as height of head capsule, scaled, with both galea halves separate from each other and curved ventro-caudad, labial palpi thin, moderately diverging and slightly up-curved, scaled, two segments visible, terminal segment pointed apically.

Thorax slightly wider than head, scaled; fore- and hindwings lanceolate, wing index 0.34 (forewing) and 0.21 (hindwing). Legs slender, small epiphysis on middle of foreleg present, two spurs on median tibia and four spurs on hind tibia, medial pair on hind tibia well before middle, spurs extremely acute at tips and covered by fine hairs; length of basal tarsomere nearly as long as remaining tarsal segments together, all tarsal segments with apical pair of short spines ventrally (Fig. 6 ). Venation heteroneurous (Fig. 7 ): forewing with four radial veins and a single, unbranched media present, Cu 1 a and Cu 1 b present, underside of Sc with short retinaculum; hindwing venation reduced, with one radial and one medial vein present; one frenular bristle present which hooks behind some scales forming a retinaculum at ventral base of forewing Sc; cover scales on forewings elongate, deeply serrate at apical margin, ground scales smaller, weakly serrate apically (Fig. 8 ).

Abdomen sternum V with pair of small, indistinct protuberances, sternum VII longer than preceding sterna, apical margins with long scales covering uncus partially on lateral and dorsal sides.

Male genitalia (Figs 4 , 9 ): segment VIII tubular, not concealed by sternum VII ventrally; base of segment IX partially covered by preceding segment, not disclosing valvae, elongate uncus dorso-ventrally depressed, 0.15 mm wide, with rounded apical margin and protruding lateral sides forming a triangular-shaped apex; apical margin of uncus with recurved, medial hook and with short denticules and longer bristles (= sensilla trichodea).

Remarks.

When identification keys for extant taxa (e. g. Carter and Kristensen 1998; Heppner 1998; Holloway et al. 2001) are consulted to resolve the taxonomic placement of the new fossil taxon, Barthelius gen. nov. always keys out at Gelechioidea . The shape of the male uncus, which resembles species in the tribe Litini of Gelechiidae was suggestive to assign the new genus to Gelechiidae . However, the uncus is only partly visible and makes the significance of this character unclear. The important synapomorphy of Gelechiidae , the angular hindwing and its emarginated termen below apex, is absent. The hindwings are lanceolate, which is unusual for Gelechiidae . In addition, the reduced wing venation and the small size of the species are further unusual characters in Gelechiidae not supporting a placement in this family.

The systematic position of the new genus within Gelechioidea is unclear. With about 5 mm wingspan the new species and genus belong to the smallest included in Gelechioidea . The new genus has a forewing venation, similar to other gelechioid families like Coleophoridae , Elachistidae or Cosmopterigidae . Unfortunately, the hind wing venation is hardly visible and only one R and one M vein are discernible, representing a reduced stage. In the absence of any other derived, discernible characters the new genus cannot be assigned to any of the many gelechioid families at present.

The superfamily Gelechioidea is represented in Baltic amber by a species-rich and diverse fossil record for many families, e. g. Autostichidae , Coleophoridae , Cosmopterigidae , Blastobasidae , Elachistidae , Momphidae , Oecophoridae ( Sohn et al. 2012) . In the Bitterfeld amber as similar diversity can be expected to occur.

Figures

Figure 9. Barthelius pumilus gen. et sp. nov., male genitalia, ventral view.

Figures 1–4. Barthelius pumilus gen. et sp. nov., male holotype: 1. Ventral view; 2. Dorsal view; 3. Head, ventral view; 4. Abdomen, ventral view.

Figures 5–8. Barthelius pumilus gen. et sp. nov.: 5. Head, frontal view (scale: 0.5 mm); 6. Legs; 7. Fore- and hindwing venation (scale: 0.5 mm); 8. Forewing scales.