Chloronycta Schmidt & Anweiler

Schmidt, B. Christian, Wagner, David L., Zacharczenko, Brigette V., Zahiri, Reza & Anweiler, Gary G., 2014, Polyphyly of Lichen-cryptic Dagger Moths: synonymy of Agriopodes Hampson and description of a new basal acronictine genus, Chloronycta, gen. n. (Lepidoptera, Noctuidae), ZooKeys 421, pp. 115-137 : 124-127

Taxon classification Animalia Lepidoptera Noctuidae

Chloronycta Schmidt & Anweiler gen. n.

Gender.

Feminine.

Type species.

Moma tybo Barnes, 1904.

Diagnosis.

Two species are included in Chloronycta , Chloronycta tybo and an undescribed Mexican species near Chloronycta tybo , known to us from only one female specimen (Fig. 4) and therefore it is not formally described here. The only Nearctic species externally similar to Chloronycta is Acronicta fallax , but Chloronycta lacks the black bar between the reniform and orbicular spots, has the reniform and orbicular stigma finely outlined in black, and has various black markings in the subterminal space, which is entirely green in Agriopodes fallax . The two genera do not overlap in range, with Chloronycta essentially a Mexican taxon reaching southeastern Arizona, and Agriopodes fallax restricted to deciduous forests of eastern North America. Genitalic structure of the two genera is very different (Figs 5, 8, 9, 12). The main diagnostic characters for Chloronycta are 1) forewing ground colour pale bluish green and white, the green colouration not degrading to yellowish with exposure to moisture; 2) valve apex with flattened, corona-like setae; 3) vesica with a single long spine isolated at the base of the ductus ejaculatorius; 4) tympanal sclerite consisting of rounded, adjoining nodules, not flange- or scoop-like.

Description.

Head. Antenna of male simple-prismatic, such that ventral margin appears slightly serrate when viewed laterally, evenly ciliate laterally and ventrally; female antenna similar but with segments less produced ventrally; antenna with dorsal scales grey, grading to white scales over basal third, with scattered black scales; haustellum normal, approximately equal in length to that of thorax; eye smooth, round; labial palpus with 3rd segment 0.4 × length of 2nd segment; 1st segment clothed with black spatulate scales dorsally and longer, strap-like white scales ventrally; 2nd segment with short, spatulate white scales apically and basally and with black scales forming broad, dark band medially; 3rd segment with short spatulate white scales and scattered black scales; frons with short, appressed, spatulate scales and longer strap-like scales forming a medial crest near ventral margin; scales of frons white, except for a patch of black scales medio-laterally; occiput with longer spatulate white scales, with black scales forming a black medial crest-like line. Thorax. Prothoracic collar with pale bluish-green spatulate scales, bordered dorsally and along eye margin by narrower black scales; mesothorax, metathorax and tegula clothed in bluish-green spatulate scales, margin of tegula with longer hair-like scales; mesothorax with paired patch of subdorsal black scales at posterior margin; tympanal sclerite raised, rounded and spade-like; prothoracic leg with brown-black and white scaling, femur brown black dorsally and greyish white ventrally; tibia black, with a transverse medial and apical band of white scales; epiphysis 0.5 × length of tibia; tarsal segments black scaled, with a distal band of white scales; scaling pattern of meso- and metathoracic legs similar to that of prothoracic leg; tibial spines white scaled, tibial spine formula 0 -2-4. Abdomen. Clothed in a mix of brownish-grey and whitish scales, which are short, spatulate and closely appressed; A1 with a dorsal tuft of long spatulate, bluish-green scales; terminal scales white and hair-like; A8 sternites and tergites normal. Male genitalia (Fig. 8). Uncus rod-like, about 5-6 × as long as wide, with a short, curved terminal spine; tegumen roughly rhomboid and broad, 2.3 × longer than wide; vinculum with saccus well developed, base slightly constricted, 2.5 × longer than base width; valves relatively simple, straplike and parallel sided, about 4.5 × longer than wide, evenly curved in a shallow arc; sacculus moderately developed, clasper well developed but thin, slightly curved with a sharp terminus, located 4/5 distance to valve apex, ampulla absent; area between clasper and terminus covered in long fine setae, setae on outer 2/3 thicker and flattened; setae near margin of apex more robust and lance-like, directed towards base of valve; juxta well sclerotized, spinose and rasp-like dorsolaterally, dorsal margin divided; aedeagus 4.5 × longer than wide, nearly straight, slightly decurved ventrally; basal half of vesica angled slightly downward, densely clothed with small but prominent spines, curving dorsad and expanding into a large medioventral diverticulum, this about as wide as long, with 15-20 long prominent spines and two to three massive, partially fused spines at base; vesica narrows abruptly beyond diverticulum, extending anteriorly, poorly differentiated from ductus ejaculatorius; a single prominent, elongate, curved spine arising from small narrow pouch near vesica terminus / base of ductus. Female genitalia (Fig. 12). Corpus bursae elongate globose, 1.25 × longer than wide, with invaginated sclerotized area dorsally at base of ductus bursae; appendix bursae dorsal and to to right of ductus bursae, small and indistinct, tapering abruptly to ductus seminalis; ductus bursae membranous, rugose, 1.5 × longer than wide; ostium bursae moderately sclerotized, with v-shaped ventral notch; antevaginal plate somewhat sclerotized and covered with dense, minute setae, projecting caudad as a somewhat pointed scoop; apophyses short, posterior apophysis 0.8 × and anterior apophysis 0.7 × height of papillae; papillae anales densely setose, margin quadrangular with slightly protuberant ventrocaudal angle.

Biology and distribution.

Chloronycta occurs in the mountainous regions from Mexico to south-eastern Arizona and southwestern New Mexico, where it reaches the northern terminus of its core range in the Sierra Madre Occidental. Chloronycta tybo occurs in canyons and mid-elevation wooded habitats, particularly riparian corridors where the larval host plant, Fraxinus velutina , grows. The larva and host plant of Chloronycta tybo are described here for the first time. The larval description under Agriopodes tybo in Powell and Opler (2009), based on an account by J. A. Comstock, actually refers to Comstock’s (1957) description of Agriopodes viridata (Harvey), now placed in the genus Bryolymnia ( Noctuinae , Elaphriini ; Lafontaine et al. 2010).

The first two larval instars (Fig. 17) are leaf skeletonizers that remove patches of leaf tissue from the lower leaf surface. Middle (Fig. 18) and late instars feed from a leaf edge, always from the underside of a blade.

Ultimate instar larva (Fig. 19) (total length to 26 mm, n = 3) waxy green, integument translucent, body thickest through A3-A5, strongly tapered rearward. Broken middorsal stripe composed of single lines on T2, T3, and A9, and anterior and posterior lines on A1-A8; broad, creamy subdorsal stripe that gradually widens posteriorly, extending from T1 through to and including anal plate. D1 and D2 pinacula free on all segments. Primary setae only, these fine; D, SD, L, and SV group setae borne from cream-yellow, pimple-like pinacula embedded within a pale yellow spot; longest setae black. One additional yellow subventral spot on T1-T3; four additional yellow lateral spots on A1-A8. D2 on T2 extending well forward of head. D2 on all abdominal segments 1.5 × longer than D1. SD1 and L2 very long on abdominal segments, circa 2 × length of an abdominal segment. D2 setae on A9 and A10 elongate, trailing behind body. Prolegs with 32-35 crochets. Spiracles tan yellow with brown peritreme. Entire integument microspinulose. Head immaculate pale green, shiny, translucent; labrum creamy. Prepupal larva flushed with red.

Prepupae tunnel into punky wood when available to form a pupal crypt, largely free of silk, with the exception of that used to weave the frass-silk cover that renders the pupal chamber essentially invisible to the untrained eye.

Remarks.

Few acronictine groups have appreciable Neotropical representation (there are no confirmed South American Acronictinae ). The majority of species are temperate and cold temperate; one exception in the New World is the Acronicta theodora Schaus group, which reaches Costa Rica. Acronictine genera are most diverse in temperate Asia but many genera, subgenera and species-groups are shared between the two realms (e.g. Harrisimemna Grote, Simyra Ochsenheimer and Acronicta subgenera Acronicta , Jocheara Hübner, and Hyboma Hübner). Chloronycta may also be derived from an Asian ancestral group, although there are admittedly no obvious sister taxa- Moma Hübner and Nacna Fletcher are similar in facies, but neither belong to the Acronictinae (Wagner et al., in prep).

Despite the very similar forewing colouration of Chloronycta to Acronicta fallax the two share no uniquely derived structural traits; DNA barcode sequence also does not support an association between with these taxa. Genitalic structure in Chloronycta is unique among Acronictinae , and no close relatives are evident. The simple valve structure, short saccular process along the ventral valve margin, and weakly-developed corona are shared by the Asian acronictine genus Subleuconycta Kozhanchikov ( Kononenko and Han 2007). Larvae of this Old World genus are not known.

As there are no unequivocal adult or larval autapomorphies for Acronictinae ( Kitching and Rawlins 1998; Wagner 2007a, b), we also examined the possibility of Chloronycta tybo belonging to other basal trifine subfamilies, most notably the Amphipyrinae , Psaphidini , which share some similarities with Chloronycta tybo (elongate valve, flattened setae forming valve corona, green forewing colouration, elongate tegumen). As is the case for Acronictinae ( Beck 1999; Wagner 2007a, b), the best diagnostic characters for Psaphidini are those of the immature stages ( Wagner et al. 2008). The larva of Chloronycta tybo shares a number of similarities with those of Comachara Franclemont and Polygrammate Hübner (Fig. 20; Wagner et al. 2011); all three genera share a similar ground colour; long, slender, darkened dorsal setae; proportionately large, pale green, smooth and unmarked head capsule; thickened subdorsal line and broken middorsal stripe represented by anterior and posterior fragments. Most significantly among the shared features, the first two sets of prolegs are somewhat reduced in size in all three genera. However, the absence of secondary setae immediately differentiates Chloronycta tybo from all other North American Acronictinae except Cerma . Behavioral characters linking Chloronycta tybo to many Acronictinae include the wood-tunneling habits of the prepupae; mature larvae excavate pupal chambers in punky wood, then seal the entrance with a sheeting of silk and frass in the same fashion as various acronictine genera. However, while tunneling into wood, Chloronycta tybo larvae do not roll the frass shavings into balls as do some basal members of the Acronictinae (e. g., Comachara , Harrisimemna , and Polygrammate ) ( Wagner 2007a, b). Chloronycta tybo turns reddish as a prepupa, as do nearly all wood-tunneling Acronictinae .

The following adult characters associate Chloronycta with the Acronictinae : 1) a black ‘eye-stripe,’ which in the natural resting position of the moth is formed by black scaling on the middle of labial palpus segment 2, on the prothoracic collar behind the eye, and extending into the basal dash of the forewing; 2) dorsal tuft of scales on A1 (occurring also in unrelated subfamilies such as Plusiinae , but absent in Psaphidini ); 3) legs strongly banded in black and white, shared with other acronictines including Polygrammate , Harrisimemna , and Cerma ( Wagner 2007a, b), but absent in most Amphipyrinae , Psaphidini (present in Feralia and Miracavira ); 4) flattened, dome-shaped eggs; and 5) Oleaceae as a larval host plant family. The use of Fraxinus is very rare among noctuids, only six other North American species (none acronictines) are known to do so (Wagner 2007; Wagner, in prep.). Yet, a number of Asian acronictine genera ( Craniophora Snellen, Acronicta subgenus Plataplecta Butler, Thalatha Walker, Thalathoides Holloway) specialize on this family ( Holloway 1989), suggesting and ancient link between Chloronycta and the diverse Oleaceae -feeding genera of eastern Asia.

The discovery of a weakly-developed valval corona is noteworthy as all Acronictinae were previously thought to lack this structure ( Fibiger and Lafontaine 2005; Lafontaine and Fibiger 2006). If placed correctly in the Acronictinae , the Asian Subleuconycta would provide a further example of a corona ( Kononenko and Han 2007) in the dagger subfamily. The confirmed presence of this male genitalic trait considerably strengthens the hypothesis that Acronictinae are related to the Amphipyrinae -group of noctuid subfamilies, and that the presence of secondary larval setae, shared with the more basal Pantheinae lineages, is homoplasious ( Zahiri et al. 2013b).