Platyja subtracta, Zilli & Vos, 2021

Zilli, Alberto & Vos, Rob de, 2021, The sumatrana species group of the genus Platyja with descriptions of four new species (Lepidoptera: Erebidae), Fragmenta entomologica 53 (2), pp. 391-410 : 396-403

Platyja subtracta sp. n.

Description

Male (Figs 5-6, 9-10, 27)

Habitus. Length of forewing: 30-35 mm. Head large, frons flat, vertex with thick vestiture of hair-like scales, eye globular, antenna mellow honey-coloured, with long opposite rami in basal half of flagellum, labial palpus with regularly arched and compactly scaled second joint, third joint very short rod-like, feebly securiform at apex. Patagi- um long, with compact vestiture of hair-like scales, tegula long, similarly scaled, meso-metanotum smoothly scaled. Ground colour of head, notum and abdomen uniformly dark chocolate brown, pectus blackish brown tufted. Forewing broad subtriangular, with costa well bowed before apex, slightly crenulate termen whose overall trend is almost straight and slightly convex anal margin; ground colour dark chocolate brown, occasionally with very feeble and patchy orangeish brown irroration in parts of the median and apical fields, Platyja pattern (see Zilli et al., 2021) feebly darker than ground colour, orbicular stigma either indistinct or barely discernible as a grey circular spot, reniform irregularly discoidal, orangeish brown, postmedial line regularly arched between discal cell and apical area, crenulate in correspondence with veins, adterminal band and fringe mostly beige, with alternating series of paler and darker lines; hindwing dark chocolate brown, except for paler costal area, and adterminal band, more evidently tinged lilac; postmedial line feebly evident, crenulate. Underside of wings medium brown irrorated with paler brown scales, discal spots and postmedial lines well distinct, darker brown than the ground colour, the lines regularly arched. Foreleg stout, with large coxa, thick, slightly arcuate femur and dilated tibia, both with invagination on inner side to host conspicuous dark blackish brown tufts, tarsus comparatively short and thick; midleg with very stout and arcuate femur and swollen tibia hosting tufts, but tarsus slender; hindleg slender, with middorsal and midventral scale crests along tibia; profemur and all tibiae unarmed; spurs very long and thin, inner ones half the length of outer ones or shorter, their formula 0-2-4. Abdomen slender and comparatively long tufted, especially dorsally at base.

Male genitalia (Figs 40-45, 54-57). Tegumen long and narrow, vinculum slightly longer than tegumen, V-shaped, with robust arms; valva broad subrectangular with expand- ed cucullus, saccular lobe broad-based with sharp-point- ed, externally curved apex, cucullus with short and wide, thumb-like apical process and broadly rounded terminal plate; juxta asymmetrical, consisting of paired strips separated midventrally by membrane, the left strip shorter, the right one very sinuous, consisting of basal broader plate and apical, strongly sclerotised cup-like extension wrap- ping from below the ventral part of manica penis; uncus slightly arched ventrally, feebly incrassate before apical, recurved hook; tuba analis with long and narrow, sclerotised scaphium. Phallus sinuous, distally prolonged into sharp awl-like apex, so that everted vesica is not even the most distal component of phallus and ‘stretches down like a flag from its pole’, coecum shortly bilobed, vesica with long tubular anteriorly oriented diverticulum tipped by cornutus, short posteriorly oriented one bearing a variable number (2-7) of very stout cornuti before constriction leading to thin, finger-like apex, and numerous smaller, unarmed conical diverticula.

Female (Figs 19-20)

Habitus. Length of forewing 30-36 mm. Head and notum as in male, with the exception of filiform antenna, and longer third joint of labial palpus, paler orangeish to lilac brown ground colour and less thick scale vestiture. Forewing broad, similar in shape to male, with more smoothly convex, gently crenulate termen and feebly falcate apex; ground colour medium brown with variable mottling from lilac to orange tinge, Platyja pattern well evident, orbicular a grey circular spot filled by ground colour, reniform orangeish to yellowish brown, trend of postmedial line as in male but well distinct, adterminal band darker, less contrasting in colour with wing disc than in male, extensively irrorated lilac with thin indigo midline, which is slightly crenulate or irregularly interrupted at veins; hindwing medium brown with some lilac irroration, paler below costa; postmedial line as dark grey dots in correspondence with veins, adterminal line as in forewing. Legs slender. Abdomen coloured as hindwing, with shorter scaling than in male. Underside of body trunk pale lilac brown, of wings also, with pinkish white sprinkles all over, and minute postmedial pinkish white streaks preceded by dark lilac suffusion at veins, this suffusion more continuous and drawing a better expressed postmedial line on hindwing than in forewing.

Female genitalia (Figs 68, 73). Lodix lobes strongly asymmetrical, with inner edge of left one greatly overlapping right one. Tergum A8 narrowed latero-ventrally into paired belts that fuse antero-ventrally with broad lamella postvaginalis, ductus bursae flat, feebly narrowed and curved to right anteriorly, bursa copulatrix large, with very wide posterior section trochoidal in shape, this with the wall of its left (cervical) part conspicuously sclerotised, and narrower oblong-ovate fundus, appendix bursae small conical, pointing posteriorly from posterior right of trochoidal part; apophyses anteriores short rod-like; ovipos- itor short, papillae anales large, elongate subrectangular, sparsely setose (but not at very base) with long setae and belt of much shorter and denser setae along their distal edges; apophyses posteriores short rod-like.

Material examined. Type material. [ Papua New Guinea]: Holotypus: ♂, British New Guinea , Hydrographer Mts , 2500 ft, Jan [uary] 1918, Eichorn Bros. (Rothschild Bequest 1939-1), NHMUK010918637 , in NHMUK (Fig. 5) ;

Paratypi (34♂♂, 11♀♀): [ Indonesia] ‘ Dutch New Guinea’ [West Papua Province]: 2♂♂, Waigeu, Camp Nok , 2,500 ft, iv.1938; 2♀♀, Central Arfak Mts , Ninay Valley , 3500 ft, Nov. [19]08 to Jan. [19]09; these (2♂♂, 2♀♀) in NHMUK ; 1♂, Birdshead Peninsula, Tuan Wowi (nr Andai ), 240 m, primary lowlandforest, at light, 2.XI.1993, A.J. de Boer, A.L.M. Rutten & R . de Vos , in RMNH ; [Papua Province]: 1♂, Humboldt Bay Distr. [sic], Uskwar, 4.[?].1934; 2♂♂, Snow Mts. [= Maoke Mts], Upper Setekwa R [iver], 2-3000 ft, Sept. 1910, A.S Meek; 6♂♂, 3♀♀, nr. Oetakwa R [iver], up to 3500 ft, x. xii.1910, Meek; 1♂, 25 miles south of Wangaar, Nomnagihé, 2000 ft, Jan.-Feb. 1921, C. F. & J. Pratt; 1♂, Jobi [= Yapen], An- sus, I. V. V . [sic] [18]97, W. Doherty; these (11♂♂, 3♀♀) in NHMUK ; 1♀, Arso District, Uskwar , 21.XII.1937 , leg. W. Stüber; 1♂, 1♀, Waris district, Ampas , 20.XI.1938 , leg. W. Stüber; 1♂, idem, 17.VIII.1939; 1♀, “Bivak-Ins.” [= camp in Noord-River ( Lorentz River ), expedition 1909-1910]; these (2♂♂, 3♀♀) in RMNH ; [ Papua New Guinea] ‘ British New Guinea’: 3♂♂, Hydrographer Mts , 2500 ft, Jan. 1918, Eichorn Bros.; 1♂ , idem, Jan.-Feb. 1918; 1♂ , idem, M. [March or May] 1918; 1♂ , idem, April 1918; 5♂♂ , idem, Jan.-May 1918; 2♂♂, Milne Bay, XI.[18]98, A.S. Meek; 2♂♂ , idem, XII.[18]98; 1♂, 1♀ , idem, I.[18]99; 1♂ , idem, II.18[99]; 1♂, Biagi, Mambare R [iver], 5000 ft, Meek; 1♀, upper Waria River, Saiko, Bubu River , 5500’, Sept-Beg [inning] Oct. 1936, F. Shaw Mayer; 1♀, Holnic- ote B[ay], to Owen Stanley Range, Rohu; these (15♂♂, 2♀♀) in NHMUK ;

Non-type material (3♂♂, 1♀): 2♂♂, Dampier Isl. [= Karkar], Feb. & March 1914, Meek’s Expedition; 1♂, 1♀, Fergusson I [sland], xii.[18]94, A.S. Meek; these (3♂♂, 1♀) in NHMUK .

Distribution. Widespread in New Guinea from the Birdshead Peninsula (= Doberai, Vogelkop) to the Owen Stanley Range and the Milne Bay Province in Papua New Guinea, it may also locally coexist with and show the same adult phenology of P. cyanocraspis . In the peripheral islands to New Guinea, its presence has been assessed in Waigeo (Raja Ampat group), Jobi (= Yapen) (Cenderawasih Bay), Dampier (= Karkar) (Bismarck Sea) and Fergusson (D’Entrecasteaux group) ( Fig. 76 ).

Etymology. The name of the new species is based on Latin “ subtracta ”, meaning ‘taken out’, in order to emphasise that this species is excerpted from the concept of P. cyanocraspis until now in use. The name is a feminine adjec- tive agreeing in gender with the generic name.

Diagnostic remarks. Males of the new species can be easily recognised from those of sympatric P. cyanocraspis by the paler, honey-coloured antennae with much longer rami in the basal half of the flagellum, the smaller labial palpi with shorter terminal joint, almost half the length of cyanocraspis , the reniform stigma more discoidal in shape, without a small accessory spot below, which is also less outstanding with respect to the ground colour, the postmedial line of forewing which runs closer to the reniform and draws a smoothly convex arch between the discal cell and apical area, so that the width of the outer lobe of the median field is smaller, and the adterminal band of forewing with a ochre tinge; on the underside, the wings are medium brown with well distinct discal spots and postmedial lines on both wings, and the legs are more strongly tufted with conspicuous blackish brown tufting on both femora and tibiae of fore- and midleg. Males are on average also larger sized and duller coloured. As regards the females, as noted under P. cyanocraspis , in P. subtracta sp. n. the trend of the crenulate postmedial line of forewing is smoothly arched beyond the reniform, and the pale adterminal band of forewing is slightly wider and crossed by a narrower indigo midline, that is more waved or interrupt- ed at veins. In the hindwing, the lilac suffusion proximal to the midline of the adterminal band is usually slightly wid- er. In the male genitalia, the most conspicuous differences between the two species occur in the saccular lobe, sharply pointed and externally curved in subtracta , and the cucullus, with large rounded terminal plate that broadly protrudes ventrally and short, thumb-like superior process in this species. The phallus of subtracta is of the awl-like type, but its apical sharp tip is only slightly outcurved, not sharply flexed externally as in cyanocraspis , and the vesica has longer anteriorly directed diverticulum, shorter and stouter posteriorly directed one which bears lateral crest of stout cornuti before digitiform termination instead of one apical cornutus, and the third longest diverticulum is without cornutus, other minor diverticula also showing different configurations. In the female genitalia, the overlap between the lodix lobes is more extended and the bursa copulatrix is much larger posteriorly, trochoidal in shape, and with large cervical sclerotization to the left bulging perpendicularly to the axis of bursa, and due to this shape the constriction with the narrower, obovate fundus is more evident.

The smaller size, less bowed forewing costa and lack of a white apical patch on the hindwing will enable an easy distinction of males of subtracta from those of lecerfi stat. n., but the authors have been unable to find any outstanding external clue to separate the former from the other endemics of the sub-group settled in smaller islands, with the only exceptions of P. vityaz sp. n. from the Bismarck archipelago, whose androconial tufts on the legs are as yellow as in cyanocraspis , not brown, and the terminal joints of labial palpi, which appear to be shortest in subtracta . All species can in any case be reliably distinguished by differences in the genitalia. Platyja togutila sp. n. has trilobate cucullus and is one of the species with blunt, not awl-shaped phallus sheath, so is the phallus of P. vityaz , which furthermore has very short, subconical, and apically rounded saccular lobe of valva and straight distal edge of cucullus. Females of these two species are unknown. Really challenging is the separation between P. subtracta and P. yaleyambae sp. n. from the Louisiades, as they agree in all respects except for the configuration of one of the main diverticula of vesica, besides the smaller size of the latter and some allomorphic differences in the female genitalia (see under this species).

Platyja lecerfi A.E. Prout, 1922 stat. n. (Figs 1-2, 17-18, 29) Platyja cyanocraspis lecerfi A.E. Prout, 1922 . The Bulletin of the Hill Museum 1 (2): 235; (3) (1924): pl. 20, figs 3-4. Locus typicus: Central Ceram … Manusela, 6,000 feet. Syntypi 1♂, 1♀, in NHMUK [examined] (Figs 1, 17).

Material examined. [ Indonesia: Maluku Province]: [Buru]: 1♀, Central West Buru, Gamoe Mrapat , 5000 ft, 3-4 ‘[19]22, C.F. & J. Pratt ; 2♂♂, 1♀, Central Buru, Kako Tagalago , 2700 ft, May 1922, C.F. & J. Pratt (1♂ in- correctly labelled “ paratype ”) ; [Seram]: 1♂, 1♀ syntypi , Central Ceram, Manusela , 6000 ft, Oct.-Dec. 1919, C.F. & J. Pratt ; 1♂, Seram, Gunung Kobipoto north slopes, 900 m, lowland forest, Aug.-Sept. 1987, J.D. Holloway, D. T. Jones et al.; all in NHMUK .

Distribution. So far known only from Seram (= Ceram) and Buru in the Moluccas ( Fig. 76 ).

Diagnostic remarks. Possibly the largest-sized species of Platyja overall, easily recognisable in the male sex from other Moluccan and Papuan relatives by the conspicuous white patch in the apical area of hindwing. On the underside, the male is similar but duller coloured than that of P. subtracta sp. n., and with less conspicuous pattern elements. The female is similar to those of other members of the group but with broader wings, with more convex costa and termen of forewing, pattern elements more weakly expressed, essentially matching in tinge and features of postmedial line female subtracta , but with thick and continuous indigo midline of the forewing adterminal band, and lilac suffusion before dark brown adterminal line of hindwing which is of uneven width, distinctly broadened anteriorly towards apical area. In the male genitalia (Figs 31-32, 50-51), the broad-based, outwardly curved pointed saccular lobes are shared with some other species, namely subtracta , yaleyambae sp. n. and togutila sp. n., but the first two of this set have awl-like phallus and rounded cucullus, while the cucullus of togutila is multilobed, contrary to the straight one with small apical process of lecerfi , a species which also lacks the awl-like phallus. The cucullus shape of P. lecerfi is not dissimilar from that of P. vityaz sp. n., but this species has stouter apical process of cucullus, weakly pronounced saccular lobes and broader juxta with more conspicuous apical process of the right plate. All species strongly differ also in the configuration of vesicae. In the female genitalia the lodix is diagnostic, being sub- trapezoid in shape with symmetrical lobes, and the bursa copulatrix is large and ovate, with weakly sclerotised cervix and no constriction between this and the fundus bursae (Figs 66, 71).

Taxonomic remarks. Comparison of genitalia configurations of this species and other relatives leaves no doubt that specific status needs to be conferred to this taxon, which had originally been described as a subspecies of P. cyanocraspis .

Figures

Fig. 76 – Distribution of species of the Platyja sumatrana-group (populations from New Britain and Rook Island [= Umboi, Siassi] combined as vityaz s.l.; see explanation in text).