A review of Leucosigma Druce, 1908: a newly discovered case of fern-feeding and descriptions of three new species (Lepidoptera, Noctuidae)

Abstract Chytonidia Schaus, 1914, is one of two noctuine genera originally described by Schaus that includes species recently found to feed on fern foliage (Pteridophyta) as larvae. By examining museum specimens, including type material and reared specimens accompanied by DNA barcode data, Chytonidia Schaus, 1914, syn. n. is synonymized with Leucosigma Druce, 1908, all currently recognized species are re-described, including males of three species described from female holotypes, and three new species are described: Leucosigmasolisae Goldstein, sp. n., Leucosigmapoolei Goldstein, sp. n., and L.schausi Goldstein, sp. n. Images of adults and, where available, larvae as well as dissected genitalia are presented, with a key to adults.


Introduction
Chytonidia Schaus, 1914 represents one of two noctuine genera (Lepidoptera: Noctuidae) described by Schaus (1914) that have recently been found feeding on ferns (Pteridophyta) as wild-caught caterpillars inventoried at Área de Conservación Guanacaste (ACG), northwestern Costa Rica. Fern-feeding (pteridivory) by herbivorous insects is of interest because the age and toxicity of ferns, coupled with the alleged rarity of fern specialists, have occasioned a modest literature that includes hypotheses of their origins (e.g., Balick et al. 1978, Cooper-Driver 1980, Hendrix 1980, Radhika et al. 2012. However, caterpillar sampling efforts during the last four decades in ACG (Janzen and Hallwachs 2016) have documented numerous pteridivorous caterpillars, most of them specialists and most previously unknown. In an effort to characterize better the prevalence of fern-feeding behaviors, as well as to serve the larger aims of Neotropical noctuid systematics, certain basic revisionary work necessary to examine the origins and extent of caterpillar pteridivory more precisely has been undertaken. This paper is a contribution to the systematics of noctuine genera now known to comprise pteridivores, our immediate purpose being to clarify the boundaries of one such genus, describe new species discovered through efforts at ACG, associate undetermined specimens with valid names, and collate life history information to the extent possible.
In the course of this work, existing collection material is complemented with recently reared specimens accompanied by life history data and DNA barcode data, the familiar ~657bp sequence from within the cytochrome oxidase I mitochondrial gene. These data coupled with comparative morphological observations, particularly those of the male genitalic complex, enable the revised taxonomic circumscriptions and descriptions of otherwise cryptic species presented here, and supplemented by a companion piece on the related pteridivorous genus Lophomyra Schaus, 1911(Goldstein et al. 2018.

Materials and methods
Pinned specimens were examined with an incandescent light source. Genitalic preparations follow Clarke (1941) in part and Lafontaine (2004), but staining with chlorazol black and slide mounting in euparal. Dissections followed either an overnight room-temperature soak in supersaturated sodium hydroxide or a 15 minute heated soak, and were examined under dissecting microscopes prior to slide mounting. Photographs were made using the Microptics and Visionary Digital imaging systems and images manipulated with Adobe Photoshop (Adobe Systems, Mountain View, CA). Measurements were made with the aid of an ocular micrometer. Forewing length was measured from the center of the axillary area to the apex of the forewing. Terminology generally follows Lafontaine (1998Lafontaine ( , 2004.
The descriptions by Druce (1908), Dognin (1910), and Schaus (1911Schaus ( , 1914 were thorough, although devoted primarily to wing pattern. Rather that reproduce them, gen-italia and other characters not treated in the original descriptions are emphasized, and diagnoses generated for each species. Full descriptions are presented for all new species. The complex, sometimes exaggerated structures associated with the male clasping apparatus requires that the terminology be clarified surrounding at least four sets of homologous structures common to all species examined. These are enumerated in the re-description of the genus and figured and labeled accordingly in Figures 111-126 of select specimens as reference. Because of their unusual configuration, associating these structures unambiguously to corresponding features in the traditional system of Forbes is not straightforward. Forbes himself noted in his introduction to the male genitalia of noctuids that "Here the problem is not to find characters for separation, but to find enough resemblances to make possible the identification of parts" (Forbes 1954: 12). In the case of Leucosigma, the appearance of several variously sclerotized structures within the valve complicates the differentiation of clasper from cucullus, for example. Rather than introduce any new vocabularies, our descriptions are anchored in the least ambiguous terms possible, explaining sources of potential ambiguity and our decisions concerning their treatment as they arise.
Provisional (neighbor-joining) analyses of DNA barcode data informed the dissection efforts and were supplemented by partial sequencing of DNA extracted during the course of dissection of the type of Leucosigma uncifera. That extraction involved an overnight soak of the abdomen in proteinase K and sequestration of the lysate prior to soaking the abdomen in KOH per the normal dissection protocol.
For specimens recently reared or collected from ACG, the following label data precede Santa Rosa National Park (SRNP) identifier codes, and are not repeated as label data except for newly designated types: Voucher: D.H. Janzen & W. Hallwachs DB: http://janzen.sas.upenn.edu Area de Conservacion Guanacaste, COSTA RICA.

Repository abbreviations
The following abbreviations refer to collections from which specimens form the basis of this study: Dognin, 1910. Although the genus was no longer monobasic, its nomenclatural composition was substantially reshaped. While transferring commixta to Lophomyra Schaus, 1911 in a separate paper (Goldstein et al. 2018, this issue), we here synonymize Chytonidia with Leucosigma Druce, 1908) based on a range of morphological characters and in particular similarities in male genitalia. Similarities in adult morphology, wing pattern, larval behavior and a small portion of the mitochondrial genome of Leucosigma species to species of Chytonidia, including both type species, require that Leucosigma be recognized as the senior synonym of Chytonidia.

Type species. Leucosigma uncifera
Diagnosis. Species of Leucosigma are diagnosed most readily by the male genitalia, in particular the nature of the highly differentiated clasping architecture, the most striking feature of which is the heavily sclerotized pincer-like cucullus on each valve. In referring to this as a cucullus, we do not interpret it as homologous to the clasper sensu Forbes; although derived from the basal sclerite, it is distinct if not entirely free of the more reduced clasper proper, which appears embedded within the sacculus and free of the basal sclerite. The cucullus bears a swollen, often bulb-like apex with a single heavily sclerotized spine, and a setose usually finger-like dorsal process (swollen apically in L. viridipicta). These most heavily sclerotized parts of the cucullus may appear simple and pincer-like as in L. uncifera, L. poolei, and L. solisae; recurved or falcate as in L. albimixta; asymmetrically distended with sinuate edges as in L. chloe; or elongate as in L. schausi.
Description. Head. Labial palpus upturned, densely scaled; second segment usually longer than combined length of the first and third. Eyes smooth or sparsely hairy. Antennae setose-ciliate; bifasciculate in males, scaled above. Thorax. Collar green towards the base, the remainder of the thoracic vestiture more uniformly brown, but scales actually pale at the base. Wings. With the exception of the type species L. uncifera, which exhibits dominantly reddish or russet forewing coloration, the forewings of Leucosigma species are mottled with a mixture of brown and mossy green, particularly in the medial and terminal areas. Reniform and orbicular spots elongate and usually fused ventrally or nearly so, forming a roughly U-shaped stigma. At least four costal striae present. Sexual dimorphism in wing pattern is most conspicuous in the hind wings, which tend to be more uniformly dark gray in the females and paler basally in the males. Legs. Femoral and tibial scales always with an admixture of lime green among the tan and "lilacine" (cf. Schaus 1914: 488); a single pair of striped mid-tibial spurs, two pairs on hind-tibiae; three rows of tibial spines on all legs. Abdomen. Vestiture usually paler than on thorax and concolor-ous with hind wing surfaces. Abdomen without coremata, brushes, pockets or levers. Male genitalia. Uncus setose and variously tufted, crested, sinuate, or (in L. viridipicta) elongate and densely covered with clustered setae throughout. Tegumen hemi-circular to oblong, in some species raised at the base of the uncus. Vinculum shallow U-or V-shaped. Saccus bluntly pointed, rounded, or squared. Valves symmetrical, highly differentiated. For reference, we call attention to four structures numbered 1-4 in Figs 111-118 which account for much of the conspicuous diagnostic variation and which appear throughout the key and descriptions to follow: (1) the sacculus/saccular extension; (2) the cucullus, identified as such by virtue of reëntrant setae sensu Forbes (1954: 13) and what may be interpreted as an anal spine, as well as (3) a finger-like dorsal process which arcs dorso-medially in situ such that the apices of each process flank the uncus; and (4) a smaller finger-like, thorn-like or (in L. viridipicta) anvil-like clasper. Vesica unadorned, without spines or cornuti; a subbasal diverticulum ranges from rudimentary, as in L. uncifera, to a large recurved torsion in L. albimixta. Female genitalia. Papillae anales blunt, subquadrate. Posterior apophyses usually at least twice as long as anterior apophyses. Lamellae antevaginales robust, ranging from narrowly concave or cup-like to more deeply invaginate, apparently co-developed with colliculum. Colliculum usually well developed but reduced or absent in some species. Ductus bursae otherwise unsclerotized, straight or with minimal torsions, attaching dorso-caudally to the corpus, sometimes with a small pre-collicular lobe. Corpus bursae without signa, oblong, sometimes appearing subtriangular when distended by presence of spermatophore(s). Appendix bursae undifferentiated except as a swollen ventral point of attachment to the ductus seminalis. Spermatophore collum, when visible, appears with a single loop; frenum with a concave face matching the interior surface of appendix bursae at its point of attachment to the ductus seminalis. Paired pad-like sternal sclerotizations on A7 are visible in some specimens.
Distribution. Mexico, Caribbean, Central and South America. Biology. All known caterpillars feed on leaves of ferns (Pteridophyta).

Remarks.
As is often the case, the type species of Leucosigma is perhaps the most phenotypically atypical of the genus. Known only from adult specimens taken at lights, the life history is unknown, although it may be reasonably suspected that the larva is a fern feeder. Species circumscription and nomenclatural assignment in this work has of necessity involved a combination of recently collected specimens for which DNA barcodes have been generated and historical specimens for which they have not, these latter including (for the present, at least) type specimens, several of which are females.

Key to known species of Leucosigma based on structures of the male genitalia.
Numbers 1-4 refer to structures labeled in figures. on underside of forewing, where terminal area appears dusted in green and contrasts with medial area; postmedial line almost complete on underside of hind wing. Cucullus pincer-like, the inner edge distal to its juncture with dorsal process straight for more than half its length before bending sharply and terminating in a sharp point. Re-description. Head. Male and female antennae setose-ciliate with dorsal cupreous scales; male antennae bifasciculate. Frons, vertex, and basal two segments of labial palpus with orange/russet-colored scales; 3 rd segment palpus and antennal scape edged with white scaling. Eyes smooth.
Thorax. Patagial "fans" appearing banded, two patches of green scales towards base, purplish medially, becoming paler or sunset-orange towards the crest; remainder of prothoracic vestiture a mix of purplish and russet scales. Wings. Forewing length 10.5 mm (holotype, male), average 10.3 mm (males, n = 4), 11.0 mm (females, n = 2). Predominantly russet orange; grayish purple in the spaces between R4 and R5, M1 and M3, and CuA2 and 1A. U-shaped stigma uniformly white. Moss-green scaling in the outer part of the apical patch and in the medial area towards the inner margin. Basal, antemedial, and postmedial lines white along inner edges, black outward; medial line more faint. Underside pattern elements more distinct than in other Leucosigma species): both forewing and hind wing postmedial lines visible, the postmedial area suffused throughout with green scaling. Legs. Scales predominantly pinkish; femoral and tibial scales with an admixture of lime green; a single pair of striped mid-tibial spurs, two pairs on hind-tibiae; three rows of tibial spines on all legs.
Abdomen. Male dorsum covered uniformly in tannish-gray scales and hairs, predominantly lilac gray in females; abdominal underside more variably scaled with lilacine and reddish brown.
Immature stages. Unknown. Etymology. Likely refers to the u-shaped forewing stigma.

Biology.
The life history of this species is unknown; to our knowledge, this species has never been reared, and has only been taken at lights. All SRNP-coded specimens with DNA barcodes examined were light-trapped in ACG rain forest.
Distribution. Costa Rica, Peru. Specimens identified as L. uncifera are reported and have been DNA barcoded from Ecuador, Venezuela, and French Guiana.
Remarks. The brightly colored orange-russet Leucosigma uncifera, the type species of Leucosigma, is the most visually distinct and atypical of the entire group, but the male genitalia are strikingly similar to those of L. solisae. DNA barcode data suggest the existence of undescribed species in a complex with L. uncifera, and it is not unlikely that additional sampling will reveal that the Costa Rican species are not conspecific with typical L. uncifera. Dyar, 1914 Figs 19, 20, 29, 30;Male genitalia: Figs 61, 62, 91, 92, 115, 116;Female genitalia: Fig. 110 Leucosigma reletiva Dyar, 1914 Diagnosis. Wing patterning not readily differentiated from that of L. chloe, although overall paler in the specimens examined and figured here, possibly reflecting wear. Both L. reletiva and L. chloe have in common with L. schausi a reniform spot with a straight outer edge, squared at the lower corner. Male genitalia similar in some respects to those of L. chloe, especially in the recurved, pointed clasper, but sacculus wider and cucullus less sinuate apically, aduncate, with pronounced subapical setal fan as in L. albimixta; vesica with small distal secondary lobe.

Leucosigma reletiva
Re-description. Head. Antennae setose-ciliate, bifasciculate in males, scaled above with alternating tan and brown bands of spatulate scales. Frons, vertex, and labial palpus with mixture of gray, brown, and some purplish scales; frons paler than vertex. Eyes sparsely hairy.
Thorax. Thoracic vestiture a mix of grayish-tan scales tipped with brown, a pair of green-scaled patches at base of pagatial fan. Wings. Forewing length 11.8 mm (holotype, female), average 12.0 mm (males, n = 2). Forewing pale, slightly cupreous baso-medially such that the gray medial line stands out; fused reniform-orbicular stigmata green, outlined in white, bracket a brown patch outlined in dark brown; terminal area shaded with green; apical patch silvery white; hind wings uniformly gray above in male and female alike, hind wing undersides shaded towards costa, postmedial line broken. Legs. Scales grayish brown, mostly concolorous with thoracic vestiture; femora and tibia with an admixture of lime-green scales; a single pair of striped mid-tibial spurs, two pairs on hind-tibiae; three rows of tibial spines on all legs, as for other members of the genus.
Abdomen. Dorsum covered in uniformly tannish-brown scales and hairs; ventral side more darkly scaled with two rows of paler tan scales on either side of the medial line (cf. L. chloe, below).
Female genitalia. Posterior apophyses less than twice as long as anterior apophyses. Lamella antevaginalis V-shaped, deeply invaginated posteriorly. Ostium wide. Colliculum welldeveloped. Ductus undifferentiated except for small pre-collicular lobe. Corpus bursae obliquely shaped, sub-triangular when distended with spermatophore(s). Ductus bursae robust, not >3× long as width at middle. Colliculum present, well developed. With two spermatophores, maintaining a very roughly foot-shaped appearance, the distal (anterior) part of the bursa distended to accommodate the corpus of the spermatophore (cf. holotype of L. uncifera).
Remarks. Dyar described this species on the basis of a single female holotype specimen in poor condition which he nevertheless recognized as having kinship with L. uncifera. (Schaus, 1911 Diagnosis. Largest Leucosigma species, forewing approaching 1.5cm on average (see below), and the only species with most of the medial area of the forewing upperside dominated by green; the terminal area also with green scaling, the components of the fused reniform-orbicular swollen and outlined in white, appearing more bulbous than in any other species except the much smaller L. viridipicta, with which L. albimixta is not likely confused; terminal area well defined on hind wing underside, more extensively shaded in green than in other species; clasper swollen, fan-like and concave medially with short acutely recurved apical hook. Ductus bursae narrow as in L. poolei but point of attachment to corpus bursae dorsad; colliculum diminutive as in L. uncifera and L. poolei.

Leucosigma albimixta
Re-description. Head. Antennae setose-ciliate, bifasciculate in males, scaled above with alternating tan and brown bands of spatulate scales. Scaling on frons, vertex, and labial palpi predominantly brown, interspersed with black and white. Labial palpus with third segment relatively longer than in congeners, almost half the length of the second segment. Eyes sparsely hairy, with a post-ocular ring of dark-purplish hair-like scales.
Thorax. Collar green scaled; a sublabial green beard-like tuft observed in one male specimen (USNM 00105321). Wings. Forewing length 14.9 mm (holotype, female), average 14.4 mm (males, n = 5), 14.8 mm (females, n = 2). Medial and terminal areas of forewing dominated by green, especially so the distended "U" comprising the fused reniform-orbicular complex; basal and postmedial areas dominated by brownish-gray scaling; underside patterning concentrated in costal and terminal areas, with neither a discal spot nor robust antemedial or postmedial lines apparent excepting a partial postmedial on the forewing. Legs. Green scale tufts on inner mid-and hind-femora, the remaining femoral scales white, brown, and black, and the tibial scaling primarily green and white; a single pair of striped mid-tibial spurs, two pairs on hind-tibiae; three rows of tibial spines on all legs.
Abdomen. Uniform grayish tan above; underside a mix of white and light/dark brown with medial patches of green.
Immature stages. Known only from images (Figs 131-134). The larva of L. albimixta is predominantly light green with a fine, pale ramifying pattern and a series of raised, rust-colored lateral spiracular patches; a broken white supra-spiracular line encloses the antero-ventral half of a small dark spot above each spiracle; dorsal pinacula raised; head capsule yellow with scattered red markings; dorsum of metathoracic segment tapers downward from anterior part of A1 at 45° angle.
Leucosigma chloe (Schaus, 1914 Diagnosis. Forewing similar to that of L. reletiva but forewing overall more darkly shaded in specimens examined; reniform spot with a straight outer edge, squared at the lower corner as in L. reletiva and L. schausi; male hind wing pale basally in males, not uniformly shaded as in L. reletiva. Cucullus with highly distinct asymmetrical deformations along both edges subapically, the apical point (≈ anal spine) ventrally curved.
Thorax. Prothoracic vestiture brown, sprinkled with green; dorsal tuft well developed. Wings. Forewing length 11.8 mm (holotype, female), average 11.3 mm (males, n = 8), 11.7 mm (females, n = 8). Legs. Femora thickly scaled with brown and black, the mid-and hind-femora with green scaling in addition; tibiae uniformly less densely scaled, in pale tan; a single pair of striped mid-tibial spurs, two pairs on hind-tibiae; three rows of tibial spines on all legs.
Abdomen. Dorsum covered in uniformly tannish-brown scales and hairs; dorsolateral tufts of hairs on anterior segments; ventral side more darkly scaled with two rows of paler tan scales on either side of the medial (cf. L. reletiva, above).
Male genitalia. Most similar to L. uncifera in size, but with the shape of the cucullus at its apex highly distorted, asymmetrical. Uncus crested, distended medially, upwardly turned with long apical point and ventral crest of short setae. Tegumen with dorsal edge nearly straight, the lateral edges outwardly sub-parallel. Vinculum cup-shaped. Saccus bluntly triangulate. Juxta spade-shaped, with a mid-dorsal projection; annellar arms fused, hoop-like. Sacculus (1) tapered to a dull point, the dorsal and ventral edges straight. Edges of cucullus (2) asymmetrical, sinuate, apical spine produced along ventral edge; dorsal process (3) undifferentiated. Clasper (4) robust, recurved to a point (cf. L. reletiva). Aedeagus with distal sclerotization faintly strap-like, and minimally rugose, somewhat granular towards vesica. Vesica likewise faintly granular basad, without cornuti; subbasal diverticulum moderately distended with a pair of smaller lobes and a pouch-like invagination with a weakly sclerotized margin as in L. reletiva.
Immature stages. No images or specimens available. Biology. Caterpillars found in ACG rain forest feeding on foliage of Bolbitis portoricensis (Dryopteridaceae) and Microgramma percussa (Polypodiaceae). Of 20 reared specimens (6 males, 14 females) an average of 19 days elapsed between the onset of the prepupal stage and adult eclosion, with most individuals requiring 19 or more days.
Distribution. Costa Rica, French Guiana. Remarks. Leucosigma chloe, its synonym (and the type species) L. chloristis, and L. reletiva were all described from female holotypes. Diagnosis. Smaller than L. albimixta, with fused orbicular and reniform spots similarly swollen, but with the basal, antemedial, and postmedial lines less conspicuously highlighted in black and white. Cucullus with medial flange directed basad, its ventral edge precisely complementing the dorsal edge of clasper from which it appears to have been separated during development; apices of the costal lobes swollen.
Re-description. Head. Antennae setose-ciliate, bifasciculate in males, scaling above uniformly grayish brown. Vertex and labial palpi with scales predominantly grayish brown; frons and inner face of palpus with paler scaling. Eyes smooth.
Thorax. Prothoracic scales grayish brown, concolorous with vertex. Wings. Forewing length 10.9 mm (holotype, male), average 10.8 mm (males, n = 2). Apical patch dominantly green on forewing upperside and underside, and on underside of hind wing. Legs-Scaling predominantly tannish brown, more or less concolorous with thoracic vestiture; a single pair of striped mid-tibial spurs, two pairs on hind-tibiae; three rows of tibial spines on all legs.
Abdomen. Dorsum covered in uniformly tannish-brown scales and hairs; ventral side more darkly scaled, especially at terminal tuft; some pinkish scaling ventrally.

Distribution. French Guiana, Peru.
Remarks. Female specimens at MNHN (Paris) were not available for study. This species is noteworthy in that the uncus is covered in shingled, scale-like clusters of setae (Figs 65, 127, 128), reminiscent of other fern-feeding species in the genus Lophomyra. The relationship between these genera requires more thorough sampling and analysis of both taxa and genes. Diagnosis. Forewing terminal area and distal part of the medial area appearing more uniform purplish gray than in other species, giving the wing a smoother, less granular appearance overall. The reniform-orbicular complex forms a continuous green "Ч "(left wing) or "μ" (right wing), the outline of which is broader than in other species except L. albimixta and L. viridipicta; the green (not silvery-white) apical patch distinguishes this and the following species from other members of the genus; hind wing underside with discal spot present but unpronounced, unlike L. poolei below. Male genitalia most similar to those of L. poolei and L. uncifera, distinguished by a shorter and more gently arced distal part of the cucullus; vesica without small basal lobe as in L. poolei.
Thorax. Excepting vestiges of green visible immediately behind head, thoracic vestiture uniformly purplish gray. Wings. Forewing length 13.7 mm (holotype, male), average 13.3 mm (males, n = 3). Forewing predominantly lilacine, russet subcostally in the postmedial; apical and anal patch present; green scaling concentrated at inner margin, apical and anal patch, and Ч/μ-shaped medial stigma. Medial area cupreous; medial, antemedial, and postmedial lines visibly darker brown; terminal area green in Costa Rican specimens, more closely matching medial coloration or slightly darker reddish brown in Peruvian specimen; apical patch primarily green; forewing underside lightly suffused with green scaling in terminal area; no antemedial or postmedial lines present on underside except at most as costal striae. Legs. Scales predominantly purplish gray; femora and tibia with an admixture of lime-green among the tan-lilacine scales; a single pair of striped mid-tibial spurs, two pairs on hind-tibiae; three rows of tibial spines on all legs.
Abdomen. Vestiture uniformly tannish gray, paler than on thorax. Male genitalia. Uncus elongate, widest subapically, upwardly curved with a very small apical point, and bearing ventral setal crest. Tegumen roughly hemi-circular, excepting a deformation of the dorsal edge at the base of the uncus. Vinculum a wide V-shape; saccus blunt. Juxta pentagonal, dorsal edge horizontal; annellar arms fused, hoop-like. Sacculus (1) densely setose, tapering to a blunt extension. Cucullus (2) appears chelicerate, the sclerotized part occupying ~1/3 the overall length and bending sharply at the outer edge near the sharply pointed apex, with a subapical tuft of reëntrant spine-like setae. Dorsal process (3) coequal in width to cucullus, setose apically. Clasper (4) finger-like, gently curved. Aedeagus with minutely but differentially spinulose patch confined to apex. Vesica without cornuti; subbasal and medial diverticula reduced, with a weakly sclerotized ridge.  Diagnosis. Forewing comparable in size but slightly larger on average than that of L. chloe, smaller than L. solisae; upperside pattern intermediate between the two in several respects, sharing the Ч/μ-shaped stigma of L. solisae rather than the straight/ squared reniform of L. reletiva and L. chloe, but with the stigma narrow as in those latter species and not as swollen as in L. solisae. Likewise the overall appearance is more granular than L. solisae but with less conspicuous black edging or black wedges at the postmedial line than in L. chloe or L. reletiva. Hind wing underside with pronounced discal spot, ringed in black in both sexes. Male genitalia: Cucullus terminates in a rounded point, less acutely curved apically than in L. uncifera or L. solisae; inner edge distal to its fusion with finger-like dorsal process curving more gradually beginning in its basal half, the part distal to its articulation with the dorsal lobe the shortest among these three species.
Description. Head. Antennae setose-ciliate, bifasciculate in males, scaled above with alternating bands of gray (basal) and tan (apical). Frons, vertex and labial palpi scaled with an admixture of white, brown and black, tipped with paler scaling. Eyes smooth.
Thorax. Thoracic vestiture chocolate brown. Wings. Forewing length 10.9 mm (holotype, male), average 11.4 mm (males, n = 4), 11.0 mm (females, n = 2). Forewing dominated by chocolate-brown coloration. Hind wing underside with pronounced discal spot ringed in black in both sexes. Legs. Scaling predominantly grayish brown or purplish gray with an admixture of green especially on the hind femora; a single pair of striped mid-tibial spurs, two pairs on hind-tibiae; three rows of tibial spines on all legs.
Immature stages. Known only from images (Figs 147-154). Young caterpillars sparsely setose, particularly on dorsal pinacula; A1 with a medial white spot flanked by a pair of yellowish or cream-colored subdorsal spots that are echoed on A8 but all of which vanish in later instars; mature larva rusty brown above to the lateral line, mottled green below; dorsal markings a series of medial blackish triangles narrowed caudally, each narrow end "cupped" in a lightly mottled mossy green; the effect is one of a series of v-shaped wedges, tapering caudally and enclosed at the narrow/caudal end with green mottling; diffuse brown subdorsal coloration darkens laterally to form an undulating line with each lighter brown abdominal "trough" enclosing a spiracle; the wavy black line separates the brown spiracular triangles from their complementary, dorsally directed green counterparts, continuous with the green venter and expanding with the increasingly distended posterior segments; head capsule brown with two black facial stripes on either side of the frons; antennae yellow.
Etymology. The name poolei is given in gratitude to Dr. Robert Poole, noctuidologist and former curator at USNM, who first identified this and other species from among the reared Costa Rican material.
Distribution. Costa Rican rain forest. Remarks. Although the female genitalia are distinctive in the configuration of the ductus, the three recently reared specimens of L. poolei, comprising two females and a male with a dissociated abdomen, appear conspecific with four male specimens collected by S.S. and W.D. Duckworth in 1965, and cluster closely with both Leucosigma solisae, known only from two males, and the two specimens referred to L. reletiva. Leucosigma schausi Goldstein, sp. n. http://zoobank.org/B2CBD402-81BE-41F7- 36,37,38,45,46,47,48 Diagnosis. Most readily differentiated from other Leucosigma by the sharply pointed sclerotized saccular extentions and the elongate cucullus reminiscent of the mandibles of trap-jaw ants (Odontomachus Latreille). Forewing similar to those of L. chloe and L. reletiva, the similarities including the pale apical patch, more variably shaded with green in L. schausi, and the straight/squared reniform, appearing more "pinched" into two trianguloid green wedges in L. schausi. Terminal area of hind wing underside distinctly paler than basal and medial areas but less extensively scaled with green than L. albimixta.
Description. Head. Antennae setose-ciliate, bifasciculate in males, finely scaled above with pinkish tan. Frons, vertex and labial palpi with variously hued brown and tan scales; scaling of the palpi paler underneath and on apical segment. Palps with brown and dark brown scales, paler on apical segment. Eyes sparsely hairy.
Thorax. Anterior part of tegulae green. Wings. Forewing length 12.2 mm (holotype, male), average 12.2 mm (males, n = 8), 12.8 mm (females, n = 5). Pattern elements visible and distinct; variation in hue of brown shading a function of scale density, as the scales are more darkly colored at their tips; U-shaped fusion of reniformorbicular complex similar to that in L. poolei, above; costal striae at basal, antemedial, and postmedial lines consist of juxtaposed black and white, white distal to black in the basal and postmedial striae and black distal to white in the antemedial stria; outermost costal striae white; postmedial line a series of black crescents enclosing pale brown centers; terminal line a series of more compressed such crescents; apical patch predominantly white with some green shading; underside shading concentrated in costal and especially terminal areas of both wings; lines incomplete, typical of genus.
Legs. Most thickly scaled on femora, with mixture of colors similar to those of head predominantly brown and pinkish tan; femoral and tibial scales with an admixture of lime green; a single pair of striped mid-tibial spurs, two pairs on hind-tibiae; three rows of tibial spines on all legs.
Abdomen. Vestiture uniform pale gray, more or less concolorous with hind wings; slightly darker ventrally.
Immature stages. Known from images of reared specimens (Figs 139-146). Larva predominantly light brown, faintly shaded with green intersegmentally and laterally on A4-6; coloration generally more uniform above spiracular line, reticulate below; the familiar dorsal herring-bone pattern consisting of a row of Y-shaped markings, the arms of which terminate at the D1 pinacula, which on A1 are partially encircled with anterior cream-colored marking to form a spectacle-like mark. Thoracic segments taper dorsally. Young larvae predominantly greenish gray, with anastomosing pattern visible dorsally; thin white spiracular line beneath a broader reddish-purple supraspiracular line, the upper edge of which runs just above SD1 pinacula.
Etymology. The name schausi honors William Schaus, Jr. (January 11, 1858-June 20, 1942, USDA entomologist and curator at USNM who described both Chytonidia, herein synonymized with Leucosigma, and the genus Lophomyra, also associated with ferns. Biology. Caterpillars found feeding on foliage of rain forest Microgramma percussa (Polypodiaceae) in ACG. Six reared specimens required an average of 22.5 days between the onset of the prepupal stage to adult eclosion.

Discussion
The synonymy of Chytonidia with Leucosigma is straightforward; the circumscription of species boundaries perhaps less so. The predominance of female types among species in the L. chloe complex (L. chloe, L. chloristis, L. reletiva) is unfortunate given the predominance of conspicuous diagnostic features in males. The identification of modern Costa Rican material as conspecific with L. reletiva was made in the absence of historical specimens of males and of barcode data from the female holotype; if that determination is incorrect, then L. reletiva is likely another synonym of L. chloe and the male Costa Rican specimens will represent an undescribed species. Likewise, the pairing of an exclusively female sample of L. poolei with an exclusively male series of museum specimens is justified primarily on the basis of wing pattern, and our selection of a female holotype in this case draws from the fact that the specimen is accompanied both by barcode and rearing data.
No doubt that several species of Leucosigma remain undescribed, probably including at least one within the L. uncifera complex. Provisional (neighbor-joining) analyses of DNA barcode data corroborated the unity of Leucosigma and Chytonidia by virtue of the proximity of Costa Rican L. uncifera to species of Chytonidia, as did a partial sequence of the holotype of L. uncifera when analyzed against a sample of 1,355 noctuid specimens that inlcuded all the available known fern feeders. Since no single mitochondrial marker would be considered an adequate foundation for phylogenetic inference regardless of the analysis, we interpret analyses of COI data with caution (particularly beyond the level of closely related species), but with that said, we also note that the available barcode data are consistent with the hypothesis of Leucosigma monophyly delineated here.
Among the more intriguing morphological features are those surrounding the male clasping architecture, specifically the complex of variously sclerotized lobes and the associated arrangement of setal tufts. The possible function of these tufts as courtship structures bears further study, as do the mechanics of the unusually elaborate clasping appendages themselves. The as yet undetermined phylogenetic proximity of Leucosigma to the smaller of Schaus' pteridivorous genera Lophomyra bears on our interpretation of the collective diet breadths of each, and to whether structures such as the clustered setae on the uncus in Leucosigma viridipicta represents a symplesiomorphous condition homologous to that in Lophomyra.
In comparison with other noctuid genera now known to comprise fern-feeding species at ACG and elsewhere in the Neotropics, the phylogenetic or taxonomic breadth of host plants recorded for Leucosigma is quite narrow, restricted to Polypodiales and specifically the families Polypodiaceae and Dryopteridaceae. These represent the two most widely recorded families among Neotropical pteridivorous noctuid genera at ACG, most of which are known from a much broader range of fern families. The effort to document hostplant associations of Neotropical caterpillars supplements our understanding of unusual genera and of the distribution of fern-feeding. Although less biologically rare than previously supposed, pteridivory appears to be phylogenetically  (1-3) Holotype ♂, Peru, NHMUK010606200 (4-6) 4 Female, Costa Rica, NHMUK010606201. localized in a small number of Lepidoptera groups whose relationships remain unresolved. Beyond pinpointing these organisms' taxonomic placement, it is likely that a better sampling of genomic data and a more systematic adducement of larval characters will contribute to our understanding of tribal and subfamilial boundaries. Likewise, the non-random distribution of recorded fern hosts across noctuid genera raises a number of specific, testable questions surrounding the evolution of diet breadth, and specifically the origins of pteridivory as perhaps a derived outcome of detritivory, moss-and lichen-eating. Figures 7-12. Dorsal and ventral habitus and specimen labels of female holotypes of Chytonix chloe (7-9) and its synonym Chytonidia chloristis (10-12).