Heterobathmia megadecella, Hünefeld, Frank & Kristensen, Niels P., 2012

Hünefeld, Frank & Kristensen, Niels P., 2012, Two new heterobathmiid moth species with distinctive female genital configurations (Lepidoptera: Heterobathmiidae), Zootaxa 3281, pp. 61-68 : 62-66

Heterobathmia megadecella n. sp.

Material examined: Holotype 3: ARGENTINA: Neuquen [Province] [sta.] 12, S. M. [San Martin] de los Andes, Piedra Trampul, 1000 m, 15.x.1981, Nielsen & Karsholt, genitalia slide ESN 2241. Paratypes: Same data as holotype (33); CHILE: Osorno [Province] [sta.] 37, Parque Nacional Puyehue, Antillanca, 1100–1300 m, 14.xi.1981, Nielsen & Karsholt (23; 1Ƥ, genitalia preparation NPK 1074). All in Natural History Museum of Denmark. Wing and body vestiture well preserved in holotype and female paratype, poorly in other paratypes.

Diagnosis. Distinguishable from the other described Heterobathmia species by the male’s prominent arched dorsum X sclerite, broad, trapezoid valves, and minute medial teguminal processes, and the female’s sclerotizations on the paramedian longitudinal elevations of the membranous lower surface of the terminal unit, as well as a conspicuous sclerotization in the genital chamber. Well-preserved specimens are distinctive by the very extensive suffusion of silvery-white scales on the forewing ( Fig. 1 A).

Description: H. megadecella is generally larger than the previously named Heterobathmia species; forewing length in male 5.1–5.5 mm; in single available female 4.4 mm.

Wings. Forewing ground coloration light brown with some purplish iridescence and in well-preserved specimens with light greyish appearance due to very extensive suffusion with silvery-white scales. This suffusion may be least developed or completely lacking on a large part of the anal area, on the dorsum just beyond the tornal spot, and in an area around the Rs-M1 crossvein and M1/M2 fork, but we are uncertain to which degree absence of silvery-white scales here and (in particular) in other areas is due to accidental scale loss. Tornal spot distinctive, but + pronouncedly confluent with adjacent white scaling. Hindwing grey with purplish and greenish iridescence. In marginal ‘fringes’ of both wing pairs silvery-white piliform scales form prominent spots around R-Rs1 and M2.

Male genitalia ( Fig. 2 ). Sternum VIII with large unmelanized median area. Segment IX with ‘tegumen’ and ‘vinculum’ completely separated by narrow membranous cleft. Anteromedian vinculum margin produced into prominent paired close-set processes on common base. Tegumen relatively longer than in other described species, anterior margin strongly convex, posterior margin more strongly concave. Tegumen posteriorly without strengthened ridge (present in the other described Heterobathmia species). Lateral teguminal process longer than postgenital complex, tapering and with slight S-bend. Medial teguminal process relatively much smaller than in other named species, tapering, only slightly curved, apex pointed. Valve extremely broad, almost trapezoid; upper margin concave near base; lower hind corner slightly produced, more rounded than in other species, with densely clustered, stout sensilla; apex with particularly long and strong setae. Postgenital complex with tergum X exceptionally well developed, saddle-shaped, synscleritous with tegumen only in middle region, with smooth, glossy surface without setation. Anterior margin of tergum X almost straight, posterior margin convexly rounded. ‘Frame’ of postgenital complex clearly separate from tergum X, slender, without anterior bridge between lateral frame sclerites. Frame sclerites without lateral extensions, posteriorly strongly converging, apices medially fused. Fused apical regions of frame sclerites with numerous simple acanthae and tubular, apically pointed cuticular processes, much longer/more prominent than any counterparts in other described Heterobathmia species. Lower surface of postgenital complex densely set with very long, delicate cuticular ‘hairs’ (acanthae).

Phallus overall similar to that of the named species, strongly sclerotized, with hyaline ‘punctures’ (the nature of which still remains to be ascertained) on base of outer tube. As in previously described congeners the intima of the ejaculatory duct is sclerotized; it is produced into a seemingly eversible and purely cuticular tube terminating in a syringe-like (dorsally open) apical spine. The membranous ‘endophallus’ connecting this tube to the apex of the outer phallic tube bears a patch of melanized and + pointed scale-like protuberances arranged in a tile-like fashion; depending on the degree of protrusion of the terminal tube none or some of these protuberances may become located externally ( Fig. 2 E).

Female genitalia ( Fig. 3 ). Subgenital plate (sclerotized venter VIII plate) ≈ 1.8x length of tergum VIII. Dorsal sclerotization of terminal unit (i.e., dorsum IX+X) with area of unmelanized cuticle along mid-line. Apophyses from anterolateral corners ≈ 0.2x dorsolateral length of terminal unit. Posterior part of dorsal sclerotization appearing set off from the larger anterior part by distinctive unmelanized indentation in lower margin of dorsal sclerite. Membranous lower surface of terminal unit with paired longitudinal elevations, each of which bearing 1) a moderately melanized, posteriorly tapering plate extending beyond mid-length of elevation 2) an adjacent smaller and more anterior, strongly melanized plate, and 3) a long ribbon-like plate on anterior part of inner surface ( Fig.

3A). Last-mentioned plate as strongly melanized as the second, its blunt anterior apex extending particularly far anteriorly. Genital chamber in front of origin of ductus spermathecae remarkable for having a conspicuous annular sclerotization (gcs) encircling the invaginated thick-walled papilla on the (posteriorly produced) apex of which the ductus bursae opens into the chamber; this sclerotization is most strongly melanized around a transverse groove on its ventral surface ( Fig. 3 C).

Distribution: Known from just two localities in Neuquen Province ( Argentina) and Osorno Province ( Chile), respectively.

Phenology and bionomics: Adults were collected from 15 October to 14 November at altitudes from 1000 to 1100 (–1300) meters. Early stages, host plant affinities and life cycle are unknown to us. Judging from the account in Humphries et al. (1986) the Nothofagus host associations of all Heterobathmia species (as then recognized) were known to the late Ebbe S. Nielsen, at least as inferred from observations on the occurrence of the adult moths. We are unable to ascertain how Nielsen’s designations of the undescribed species as ‘species A–H’ in that publication relate to the entities into which he eventually sorted the bulk of the available Heterobathmia material (now in the Natural History Museum of Denmark), except that during the description of H. valvifer a few years before his untimely passing (in 2001) he informed NPK that this one was ‘species B’.

Etymology: The name megadecella refers to the extraordinarily strongly developed dorsum X sclerotization of the male. Ebbe S. Nielsen had given the preliminary name “megadeca” to specimens sorted to this taxon, and we just emended it by using the “-ella” suffix, which is in such widespread use for moths that would have belonged in Linnean Tinea .

Figures

FIGURE 1. Heterobathmia habitus. A, H. megadecella male holotype; B, H. nielsenella, female holotype.

FIGURE 2. Heterobathmia megadecella n. sp., male genitalia, details in slide preparations as prepared for previous taxonomic descriptions of congeners (A & C – E), or stacked multifocus photographs of intact specimen (B). A, dorsum IX plus postgenital complex of holotype, dorsal view; ventral acanthae on the latter visible through cleared tergum X plate; B, postabdominal apex in dorsal view of paratype, notice contrast in pigmentation and texture between dorsum IX and extraordinarily large tergum X; C, venter IX with valvae of holotype; D, phallus of holotype; E, phallic apex of paratype, part of scaly-textured connecting zone between outer tube and syringe-like process from ejaculatory duct externally exposed. fr, sclerotized ‘ frame’ of postgenital complex; mp, medial teguminal process; lp, lateral teguminal process; te, ‘ tegumen’ (dorsum IX); tX, tergal plate of segment X; vi, ‘ vinculum’ (venter IX), vl, valve.

FIGURE 3. Heterobathmia megadecella n. sp., postabdomen of unique female paratype. A, ventral view, stacked multifocus photographs of KOH-macerated specimen in ethanol, supported on ‘ Ballotili’ glass beads; B, lateral view, conventional slide mount in Euparal, rectum / anal tube partly filled with non-degradable material (including loosened wing scales), hence its position / course easily identifiable; C, magnified detail of B, showing optical section of anterior part of genital chamber. db, (non-spinose posterior part of) ductus bursae; ds, ductus spermathecae; gcs, sclerotization of invaginated thick-walled papilla in genital chamber; 1 - 2 - 3, sclerites on softwalled lower surface of terminal unit thus denoted in text.