Rhabdorthodes, Crabo, Lars G., 2018

Crabo, Lars G., 2018, A new genus and three new species of noctuid moths from western United States of America and Mexico (Lepidoptera, Noctuidae, Noctuinae, Eriopygini), ZooKeys 788, pp. 183-199 : 183-185

Rhabdorthodes gen. n.

Type species.

Rhabdorthodes pattersoni Crabo.

Gender.

Masculine.

Diagnosis.

Rhabdorthodes is a distinctive genus with characteristic male and female genitalia. The adults are small to medium-sized, forewing length 13-15.5 mm, and nondescript superficially, with even gray-brown to brown forewings with limited dark markings. The eyes have interfacetal setae. Males have a long rod like extension of the right side of the dorsal juxta (Figs 7-9) that is unknown in any other North American genus. The valves are also distinctive, with massive slightly bilaterally asymmetrical claspers with horn- and molar like processes. Females have diagnostic features of the bursa and segment A7. The posterior ductus bursae is expanded into an amorphous fleshy externally frondlike sac (Figs 10-12). Externally, sternite A7 is broad, sclerotized strongly, with a broad sculpted depression on the ventrolateral surface to each side of midline (Figs 13-15). This is most apparent in intact specimens and is observed easily under low magnification. The papillae anales are very thin and needlelike and the distal abdomen is telescopic with long intersegmental membranes.

The most closely related genus based on structure and barcodes is Protorthodes McDunnough, revised recently by Lafontaine et al. (2014). Males of Protorthodes lack the rodlike extension of the juxta that is found in Rhabdorthodes and have a normal-sized uncus. The valve of Protorthodes species differ from those of Rhabdorthodes in having a long thin ampulla of the clasper arising from the mesial surface of the valve rather than a stout curved one at the dorsal margin, and lack massive enlargement of the distal clasper with a large ventral extension. Females of Protorthodes lack or have only a small fleshy components of the anterior ductus bursae, well developed in Rhabdorthodes , and lack sculpting of the ventral seventh sternite.

The barcode of Rhabdorthodes pattersoni is closest to Protorthodes , differing from barcodes of species in this genus by at least 3.5%. The two Mexican species of Rhabdorthodes have not been barcoded.

Description.

Adults. Males and females similar in habitus. Head. Antenna biserrate, rami densely setose, total width 3-4 × shaft, anterior rami slightly longer than posterior rami (male); beadlike, biciliate (female); dorsum with small scales. Eye normal size, interfacetal setae long, curved apically. Labial palpus reaching dorsal margin of eye; sides of first two segments with short strap like scales, anterior first segment with medium-length simple and long hairl-ike scales, anterior second segment scales similar, shorter; apical segment 0.2 × second segment, scales very short. Haustellum normal. Frons unmodified, scales simple, medium length; dorsal head scales long, thin, spatulate, forked.

Thorax. Dorsal vestiture dense, long, thin, spatulate and forked scales, medium to dark gray brown; weak mesial tuft on anterior metathorax. Venter scales hair like, dense, dull brown. Legs: Tibiae without claws or other modifications, dark gray brown with scattered off-white scales; tarsi except apical segment with three rows of spine like setae, segments dark brown, ringed distally in off-white. Wings: Forewing: Length 13.0-14.0 mm (males), 13.5-15.5 mm (females), length ~ 2 × width; outer margin smoothly convex, strongest near anal angle; dorsal scales short, straplike, uniform medium to dark gray brown or brown; costa with 6 light spots on basal, antemedial, postmedial line origins and 3 spaced evenly between postmedial line and apex; lines and stigmata except subterminal line black; lines double, filling pale; subterminal line pale gray or luteous, preceding shade dark brown or black; fringe ground color. Hindwing: Outer margin slightly concave M1-M3; dorsum gray brown, lightest basally; veins and terminal line dark; fringe lighter than ground.

Abdomen. Male unmodified. Female sternite A7 (Figs 13-15) sclerotized, thickened posteriorly; posterior margin pointed bluntly in midline, concave to each side of midline; ventrolateral surface sculpted with broad central concavity with lateral raised flange (two species) or deep transverse cleft ( R. petersoni ). Male genitalia: Uncus weak, length 0.5-1 × juxta height, shorter and thinner than juxta extension, curved evenly, tapered to thin point, distal undersurface with short thin hair like setae. Juxta base hourglass shaped, elongate, height 2.2-3.3 × width; dorsum asymmetric: left lobe small, flat; right with long stout tapered rod, length 1.2-1.5 × juxta height, projecting posteriorly with slight curve ventrad and leftward. Valve length 4.3-6.0 × width, weak distal to clasper; sacculus 0.5-0.6 × valve length and 0.75-0.8 × valve width, smooth; ventral distal clasper distal to ampulla heavily sclerotized, massive, 1.0-1.2 × valve width, dorsal and ventral toothlike and hornlike processes extending beyond valve margins (dorsal extension reduced in one species); ampulla origin from bulging clasper at dorsal valve, stout, hook-shaped, base oriented 30-45° basad or perpendicular to valve, then curved distad 90-180°; digitus thin, membranous, directed distad from origin near ventral valve; cucullus weak, rounded, barely wider than “neck,” covered densely by short thin hairlike setae, lacking corona. Phallus tubular, narrow, length ~ 10 × width. Vesica membranous, length ~ 1.5 × and width 2.5 × phallus, base bent 90° left, mid-section coiled 360° counter-clockwise, distal segment bent 45° cephalad to end right or ventral to phallus; small foot-shaped basal diverticulum; no cornuti. Female genitalia: Papilla analis length 6-8 × width, thin, pointed, covered sparsely with short thin hairs on lateral surface and densely with very short thin hairs on medial tip; posterior intersegmental membranes long, eversible. Segment A8 length 1.25-1.50 × width, with sparse short thin setae; posterior apophysis 2.1-2.4 × segment A8 length; anterior apophysis 0.4 × posterior apophysis. Ostium bursae sclerotized lightly with ventral short median cleft or leathery, lacking cleft. Ductus bursae 1.5 × segment A8 length; posterior third sclerotized dorsally, expanded to fleshy frondlike structure filling most of ventral segment A7; middle third sclerotized, tubular; anterior third membranous, tubular. Corpus bursae bisaccate, corpus bursae and appendix bursae similar size; corpus bursae membranous, ovoid, length 2 × width, lacking signa; appendix bursae origin from left posterior corpus bursae, curved 270° anterior, leftward, and posterior to end to left of mid-ductus bursae; ductus seminalis at apex.

Etymology.

The name is derived from the Greek rhabdos, meaning rod, and Orthodes , a genus of moths in the tribe Eriopygini . It refers to the long extension of the male juxta.

Distribution and ecology.

Rhabdorthodes species occur in the mountains of western United States and Mexico from southern Idaho and southern Wyoming in the United States to Nuevo Léon and Durango in Mexico. Adults fly in the summer during June and July. All three species in the genus have been collected in montane forests at mid- to high elevations between 1600 and 3150 meters. The early stages are unknown for all species.

Discussion.

Assignment of this genus to subfamily Noctuinae tribe Eriopygini is based on the presence of hairy eyes, similarity of the adults to species of other genera in this tribe, and the association of the barcode of R. pattersoni sp. n. with those of Protorthodes McDunnough on neighbor-joining trees. Although almost certainly correct, this is provisional until the early stages are discovered. The main morphologic difference between tribes Hadenini and Eriopygini is in the mandible and spinneret of the larva ( Fibiger and Lafontaine 2005), currently unknown for Rhabdorthodes . This classification is supported by the presence of a long coiled vesica in males of Rhabdorthodes , since this is a typical feature of many species in the tribe Eriopygini (Fibiger and Lafontaine op. cit.).

The functions of the unique sexual characters of Rhabdorthodes can only be surmised. In males, the long rodlike extension of the juxta, diminutive uncus, and the massive sculpted ampulla of the clasper with molar- and hornlike processes are unlike any other in the Eriopygini . In the female, the fleshy enlargement of the posterior ductus bursae and the sculpted lateral segments A7 are similarly unusual. The needlelike ovipositor and telescopic distal abdomen is also distinctive, although similar modifications are known in other taxa.

The fleshy posterior ductus bursae appears gland like and might have a secretory function. It could potentially have a mechanical function as well, receiving the long juxta during copulation. Even if coupling does not occur in this fashion, the male rod must somehow engage the female. The weak uncus suggests that the rod might have supplanted all or part of its function. Similarly, the massive claspers of the distal male valve probably engage the concave pits on the posterior female abdomen. The latter modifications are analogous to those of the noctuid genus Spaelotis Boisduval ( Noctuinae, Noctuini )-illustrated in Lafontaine (1998: 73)-in which females have species-specific pits on the ventral posterior abdomen that likely receive the ampullae of the male claspers. The needlelike papillae anales and long eversible posterior abdomen of Rhabdorthodes suggest that females lay eggs deep within a specific plant structure, less likely deep in soil.