Fatellalla St Laurent & Kawahara

Laurent, Ryan A. St & Kawahara, Akito Y., 2019, Reclassification of the Sack-bearer Moths (Lepidoptera, Mimallonoidea, Mimallonidae), ZooKeys 815, pp. 1-114 : 16-17

Fatellalla St Laurent & Kawahara gen. n. Figs 104-105, 106

Type species.

Cicinnus fatella Schaus, 1905: 326, by present designation.

Etymology.

The name for this new genus is derived from the type, and only known species belonging to Fatellalla : Fatellalla fatella comb. n. The name is feminine.

Diagnosis.

This new genus can be recognized by the following combination of characters in the male (the only known sex): triangular forewings with pink antemedial and medial areas, which contrast with the orange-brown submarginal area. The submarginal area is clearly delimited by a pair of thin, straight, preapical, blackish brown postmedial lines. The rounded hindwings display the same patterning as the forewings. The coloration of the body is that of the ground color of the wings: orange-brown, with a distinct darker brown lateral line along either side of the abdomen, as well as a distinct dark brown tuft of elongated scales extending from the terminus of the abdomen. The genitalia are distinct due to the truncated, flattened uncus and the knob-like saccular process at the base of each valva, characters together not observed in any other known Mimallonidae . The gnathos plate is typical of alheitine Lacosominae; and the short, rounded valvae, narrow pair of valva apodeme arms, and thick bunch of elongate setae originating from the diaphragm are similar to those seen in Tarema and Alheita . In Fatellalla , the arms cross over each other mesally and are sharply tipped unlike in these other genera.

Apomorphies.

(1) Uncus flattened, truncated (Fig. 106I); (2) Sharply tipped valva apodeme arms which cross mesally below uniquely shaped (mesally rounded) gnathos plate (Fig. 106II).

Description.

Male.Head: Tan-brown ground color, frons dark brown, eyes very large, occupying more than two-thirds area of head, bordered posteriorly by dark scales; antenna coloration dark tan, antenna almost entirely bipectinate, distalmost 9-10 antennomers dentate; labial palpus three segmented. Thorax: Coloration pinkish orange with red hue (fading to light brown in old specimens), scales covering prothorax grayer, contrasting against lighter remainder of thorax. Legs: Coloration as for thorax, vestiture thick, long. Tibial spurs elongate, covered in scales except for tip, roughly half length of first tarsal segment. Forewing dorsum: Forewing length: 15.5-17.0 mm, avg.: 16.3 mm, wingspan: 29.0-4.5 mm, n = 2. Triangular, margin mostly straight except slightly convex below apex and slight indentation at tornus. Ground color orange brown, but antemedial and medial areas evenly tinted with pink, faint gray suffusion present submarginally. Antemedial line absent; preapical postmedial line formed by two thin, parallel dark brown lines with medial area pink coloration between them. Postmedial lines slightly wavy basally. Pink coloration of medial area does not extend beyond postmedial lines. Discal mark present as pink ovoid region slightly lighter than surrounding medial area. Fringe poorly preserved in examined specimens, but darker brown than submarginal area. Forewing ventrum: Darker brown than forewing dorsum, medial pink suffusion bleeds into submarginal area, postmedial line convex and indented at intersections with veins. Hindwing dorsum: Coloration, patterning as for forewing dorsum, but discal mark absent, submarginal area comparatively wider than medial area. Hindwing ventrum: Following same pattern as forewing ventrum, but lighter overall. Frenulum present as single bristle. Venation: Typical of Mimallonidae . Abdomen: Dorsal coloration as for thorax, laterally very dark brown, nearly black, dark coloration continues on to elongated paintbrush-like tuft of dark-brown scales extending from terminus of abdomen. Vestiture thick, long. Genitalia: (Fig. 106) n= 4. Vinculum ovoid, ventrally rounded. Paired sclerotized arms extend outward from sclerotized base of costal valva apodemes. Uncus simple, truncated distally, rectangular. Gnathos well-sclerotized, forming mesally lobed plate below uncus, gnathos spanning tegumen. Valvae small relative to tegumen + uncus, valvae rounded, hardly extending beyond vinculum-tegumen juncture. Saccular edge of valvae with heavily sclerotized knobs near valval base. Diaphragm with dense setae extending outward above phallus. Juxta fused to phallus, encircling it, lateral margins of juxta extend one quarter length of phallus as triangle directed toward apex of phallus, ventral lip of juxta connects to vinculum. Base of phallus weakly sclerotized with undefined coecum phallus. Phallus cylindrical, downwardly angled distally, vesica spiculate. Female. Unknown

Remarks.

We describe Fatellalla for F. fatella , an Amazonian species widely distributed in Ecuador, the Brazilian Amazon, and French Guiana. This species is exceptionally rare in collections, with less than ten specimens known to us in global collections. Although St Laurent et al. (2018a) did not sample F. fatella , this species clearly belongs to Lacosominae: Alheitini due to the presence of the fused gnathos “plate” which is also observed in alheitine genera Thaelia , Tarema , and Alheita . The genitalia of Fatellalla are most similar to those of Tarema and Alheita (see St Laurent et al. (2017b)), the presence of elongated valvae apodeme extensions basally not unlike those of Tarema , support a close relationship between these genera. Our morphological phylogenetic analyses also support the placement of Fatellalla within Alheitini due to close placement with several other alheitine genera, namely Alheita (Fig. 1, see also Suppl. materials 5-7). Although Fatellalla is nested within a poorly supported Alheita clade, we maintain this genus as valid pending molecular phylogenetic analyses due to the extremely divergent uncus shape and external appearance which is inconsistent with any observed Alheita . We note also a particularly long branch length (relative to other Alheita ) in our ML analyses, emphasizing the divergent morphological characters of this odd genus.

Schaus’ (1928) placement of this species in Druentica was unjustified and erroneous.