Leichosila Schmidt, 2009

Schmidt, Christian, 2009, A new genus and two new species of arctiine tiger moth (Noctuidae, Arctiinae, Arctiini) from Costa Rica, ZooKeys 9 (9), pp. 89-96 : 90-92

Leichosila Schmidt , gen. n.

urn:lsid:zoobank.org:act:37F4D9EA-EDF5-4376-B9D3-D41901CBB5A7

Type species. Leichosila talamanca Schmidt , sp. n.

Diagnosis. Leichosila can easily be distinguished externally from all other New World arctiines by the unique wing pattern and colour, consisting of a grey to whitish- grey ground colour with a pattern of dark grey-black, incomplete forewing bands that are ochre yellow centrally ( Figs 1, 2 ). Structurally, the following combination of characters is unique: male antennae simple ( Fig. 9 ), juxta very broad and shallow (5 × wider than long; Fig. 8 ); male valve lacking medioventral lobe ( Figs. 3a, 4a ), abdominal markings absent ( Figs. 1, 2 ). Th e juxta shape is a putative autapomorphy of the genus and is unlike that of any other New World spilosomine.

Description. Male (female unknown). Head – Male antenna filiform in dorsoventral view, ciliate and subserrate ventrally; segment slightly longer than wide ( Fig. 9 ); dorsal antennal scales greyish brown; palpi porrect, 3 rd segment ½ length of 2 nd segment; vestiture of palpi, frons and vertex dusty brown grey; haustellum reduced and poorly sclerotized, presumably non-functional. Thorax – Vestiture of vertex and ventrum of thorax, patagia, tegulae and legs dusty brown grey and shaggy; apex of prothoracic tibia with two subequal, blunt, triangular projections; two meso- and metathoracic tibial spurs, the posterior spur slightly longer than anterior, length of spurs approximately equal to tibial width at apex; metepisternum with rounded ridge along anterior margin, microtymbals absent. Forewing ( Figs. 1, 2 ) – length 13.4 to 16.1 mm; ground colour dark mouse grey to whitish grey; 5 transverse bands of yellowish ochre, outlined in dark charcoal grey; bands evident as five discrete cells along costa, three basal bands obsolete in medio-basal area, and again present along anal margin except for basal-most band; ochre and grey areas of three distal bands confluent in costal half, with ochre scaling extending along veins; distal band often darkest and most complete; pattern similar ventrally, but colours washed-out. Hindwing ( Figs. 1, 2 ) – ground colour dusty grey to whitish grey, with irregular dark-grey subterminal spots and medial spot, these varying in contrast from pronounced to obsolete against darker ground colour; pattern similar ventrally, but colours of subterminal spots washed-out; medial spot darker ventrally than on dorsum, often extending to costa and basally along costal margin. Abdomen – vestiture dusty brown grey dorsally and ventrally; evenly coloured without distinguishable markings ( Figs. 1, 2 ); coremata between 7 th and 8 th sternite absent ( Fig. 5 ); 8 th sternite moderately sclerotized, trapezoidal, 2 × as wide as long ( Fig. 5 ); lateral sclerites of 8 th sternite moderate sclerotized basally, mem-

branous distally, equalling width of sternite in length ( Fig. 5 ); 8 th tergite sclerotized, entire. Male genitalia – Uncus triangular to bottle-shaped in dorsal view, length 2 × that of basal width ( Figs. 6, 7 ); basal half sparsely setose; apical third flattened laterally, down curved, resembling a bird’s beak in lateral view; apex truncate in caudal view; ventrally with membranous area extending halfway to apex ( Figs. 6, 7 ); dorsal margin of tegumen recurved caudad, extending to base of uncus; valve consisting of a simple, sickle-shaped, slightly laterally flattened process ( Figs. 3a, 4a ) extending dorso-caudally as far as uncus apex (in natural position); valve devoid of processes and lobes ( Fig. 3a ), or with small sub-basal process on dorsal margin of costa ( Fig. 4a ); lateral process of transtilla consisting of a poorly delineated, sclerotized region contiguous with membranous area dorso-laterad of anellus, forming shallow, rounded pyramidal prominences directed dorsad; saccus broadly u-shaped, length equalling ¾ height of genital capsule; juxta u-shaped and slightly convex ventro-caudally, very broad and shallow, about 5 × broader than height at midline ( Fig. 8 ); phallus unadorned and relatively stout, approximately 4 × as long as wide ( Figs. 3b, 4b ); coecum strongly curved ventrad by 90°; vesica globose with four basal diverticula ( Fig. 4b ), total diameter equalling length of phallus; two diverticula positioned basally and left-laterad, adjacent to each other; two additional diverticula positioned ventro-basally and also adjacent to each other; left half of vesica scobinate, grading to smaller spicules on right side; ductus ejaculatorius positioned right laterad.

Etymology. The name is feminine in gender, and is derived from the Greek stem for lichen, leichos, and the Latin for yellow ochre, silaceus, reflecting the odd yellowochre colour of the forewing bands, very unusual for an arctiine. Th is colour pattern is presumably cryptic on lichen-covered trees.

Remarks. Th e caudally recurved dorsal margin of the tegumen and lateral lobes of the 8 th sternite of Leichosila are unique autapomorphies of the Spilosomina ( Schmidt 2007) . The morphology of the male genitalia (valve prong-like and relatively simple, uncus broadly triangular) and wing shape/pattern place Leichosila near the Hyphantria Harris group of genera, consisting of Hyphantria , “ Spilosoma ” (sensu lato), Alexicles Grote , Estigmene Hübner , and the “ Hypercompe ” permaculata (Packard) group, although I could find no synapomorphies to suggest a possible sister genus. The filiform antenna and absence of dorsal abdominal markings are rare among all spilosomines, but this condition occurs in some Hypercompe species and Spilosoma vagans (Boisduval) , respectively. An incomplete ‘barcode’ fragment (319 base pairs) of the cox1 mtDNA gene of a single L. talamanca specimen (Barcode of Life Data System ; Ratnasingham and Hebert 2007) was approximately equally divergent from species of all Hyphantria -group genera by 5.6 % to 7 %. Th is level of divergence is congruent with the highly autapomorphic morphology of Leichosila , but unfortunately does not provide possible clues to generic relationships to the rest of the group. The Hyphantria group is restricted to Central and North America (except for Estigmene albida (Stretch) which occurs south to Colombia), but Leichosila is more closely allied to this group than to Neotropical Paracles Walker and Andean “ Phragmatobia ” to which Leichosila shows some superficial similarities but structurally it is quite different.

Figures

Figures 1-2. Adult habitus of Leichosila gen. n. 1. Leichosila talamanca sp. n., male holotype. 2. Leichosila wagneri sp. n., male holotype.

Figures 6-9. Structural features of Leichosila. 6. L. talamanca, uncus (dorsal view); 7. L. wagneri, uncus (dorsal view); 8. L. talamanca, juxta; 9. L. talamanca, antenna (segments 14 – 18), ventral view (setae and cilia omitted except on segment 14).

Figures 3-5. Male genitalia of Leichosila. 3a. L. talamanca (paratype), genital capsule (ventral view); 3b. phallus (left lateral view), with inflated vesica (ventrobasal diverticulum highlighted); 4a. L. wagneri (holotype), genital capsule (ventral view); 4b. phallus (left lateral view) with inflated vesica (ventrobasal diverticulum highlighted); 5. L. talamanca, 8th abdominal sternite, showing medioventral sclerite and lateral lobes.