Philiris petriei Mueller

Mueller, Chris J., 2014, Six new species of Philiris Roeber, 1891 (Lepidoptera, Lycaenidae) from Papua New Guinea, ZooKeys 395, pp. 33-55 : 35-38

Philiris petriei Mueller sp. n. Figs 1-4, 61, 88-92, 97

Type material.

Holotype ♂ (Figs 1-3): Papua New Guinea, Whiteman Range, West New Britain Province, 1050 m, Ex-pupa, 5°59'S, 150°35'E, 20 Oct, 2013, Chris J. Müller, genitalia dissected and held in vial pinned to specimen, pupal exuvia pinned to specimen (ANIC), Registration: ANIC Database No. 31-023122. Paratypes (8 ♂♂): 4 ♂♂ labelled Papua New Guinea, Whiteman Range, West New Britain Province, 950 m, 5°58'S, 150°29'E, 10-18 Dec, 2005, Chris J. Müller (2 ♂♂ BMNH; 1 ♂ NARI; 1 ♂ EAPC); 3 ♂♂ labelled Mt. Otto summit, West New Britain Province, 1320 m, 5°33'S, 150°24'E, 19-22 Dec, 2006, Chris J. Müller (2 ♂♂ CJMC; 1 ♂ AM); 1 ♂ labelled Bainings Mts., East New Britain Province, 1000 m, 4°38'S, 152°02'E, xii.2008, L. Wills leg. (UFL).

Diagnosis.

Males of Philiris petriei sp. n. are readily distinguished from other species in the genus. Philiris petriei sp. n. is a large species with a forewing length that surpasses that of its putative congeners, Philiris harterti (Grose-Smith, 1894) and Philiris albiplaga (Joicey & Talbot, 1916). Philiris harterti occurs widely in mainland New Guinea (nominate in northern and western NG mainland; subspecies leucoma Tite, 1963 in eastern NG mainland). The holotypes of both taxa are illustrated here-in (see Figs 5-8). Philiris harterti also occurs on Yapen Island, where it is known by ssp. melanoma Tite, 1963. Philiris albiplaga is restricted to the Schouten Islands (Biak and Mefor). Since the holotype is a female specimen (Figs 11, 12), Tite (1963) designated one of two known males of Philiris albiplaga as a neallotype (Figs 9, 10).

The shape of the fore wing in Philiris petriei is slightly rounded at the apex, whereas it is pointed in the other species, particularly so in Philiris harterti . The hind wing termen is weakly serrated near the tornus in Philiris petriei , unlike in related species and the cilia on the underside of the hindwing tornal area is continuously black, as in Philiris albiplaga , whereas the cilia are mostly white in Philiris harterti and black only at the vein terminals. The underside of the forewing in Philiris petriei bears a large dark basal patch, not present in either Philiris harterti or Philiris albiplaga . The frons in Philiris petriei are black (Fig. 97), while they are rusty red and brown in Philiris harterti (Fig. 98) and Philiris albiplaga , respectively. The white area on the forewing above is much more reduced in Philiris petriei than in Philiris harterti and Philiris albiplaga , bearing more resemblance to the pattern in Philiris bicolor (Bethune-Baker, 1904), a species with red frons similar to Philiris harterti . In Philiris petriei , the forewing white patch is restricted to the inner margin and does not extend beyond vein 2, only marginally extending beyond 1b, while in Philiris harterti and Philiris albiplaga this white area continues beyond vein 2 and reaches, or exceeds, vein 3 and the edge of the cell. No obvious variation has been noted in the type series of Philiris petriei , with all specimens similar in size and maculation.

The male genitalia of Philiris petriei (Fig. 61) also show a relationship to both Philiris harterti (Fig. 62) and Philiris albiplaga (Fig. 71). However, the genitalia of the former species are larger than both Philiris harterti and Philiris albiplaga , and the sociuncus is narrowly V-shaped dorsally, whereas it is rather rounded in Philiris harterti and broadly U-shaped in Philiris albiplaga . The valva is triangular-shaped at the base in Philiris petriei , whereas it is bulbous in Philiris harterti and with conspicuous median lobes in Philiris albiplaga . The phallus is long and slender in Philiris petriei (Fig. 61c) and the vesica is boat shaped at its apex, whereas the phallus of Philiris harterti (Fig. 62c) is comparatively short and squat and the apex of the vesica is bifurcated symmetrically. The phallus of Philiris albiplaga is not clearly defined in either slide mounts of the Mefor Island male specimens but appears to be heavily sclerotized and the vesica is tongue-shaped (Fig. 71c).

Description.

♂ (Figs 1-3, 97): Forewing length 17.5 mm, antenna 11.5 mm (holotype). Head, palpus, thorax and abdomen black dorsally, white ventrally, frons black with white eye ring; antenna shaft black, ringed weakly with white, apical half of club orange-brown ventrally; legs white with black areas on tibiae.

Fore wing termen slightly convex but straight between veins 2 and 4, inner margin slightly convex; upperside with ground colour black, a restricted triangular area of white in the median and postmedian area, extending from the inner margin to midway between veins 1b and 2 and from about one-third along the termen to approximately 3 mm from the termen at the tornus, white area suffused with light grey narrowly towards base, cilia black; underside uniformly white, with apical area and termen broadly suffused with brown, a large rhomboid-shaped patch of dark brown scales extending from base to median area, cilia black.

Hind wing slightly rounded, termen weakly serrated between veins 2 and 4; upperside with ground colour black, apical area broadly white and extending along costa to near base and to the middle of the hind wing, filling distal half of cell and discocellulars, cilia black except in apical area where they are white; underside uniformly white with weak brown suffusion broadly along termen, cilia black and longer in tornal area, white at apex.

♀: Unknown.

Male genitalia (Fig. 61): Vinculum and tegumen ring broadly oval, sociuncus broad, socii with lateral margin rounded, socii weakly separated by V-shaped sinus, saccus tapered posteriorly, brachium tapered dorsally and slightly hooked at apex; valva long, symmetrical, triangular-shaped at base and tapered apically; phallus with prezonal section approximately equal in length to postzonal section, slender, with vesica apically flanged.

Etymology.

This species is named in honour of Edward A. Petrie, Sydney, Australia, renowned for his expertise in Australian Lycaenidae , in particular their life histories.

Distribution.

New Britain Island, Papua New Guinea.

Ecology.

When compared with those of the related Philiris harterti , the flight behaviour of Philiris petriei males differs in that the latter species generally flies on mountain tops (e.g. Fig. 84) from 1100 hrs until just after midday, whereas Philiris harterti does not normally appear in its hill top territories until about 1330. Males of Philiris petriei fly high, usually above six metres above the ground, whereas those of Philiris harterti generally fly much lower, between 1-4 metres above the ground. There appear to be two broods annually for the life cycle of Philiris petriei , with adults flying in November and December and again in April and May. Conversely, adults of Philiris harterti fly throughout the year in mainland New Guinea.

Parsons (1998) recorded the life history of Philiris harterti on saplings of Litsea callophyllantha ( Lauraceae ). A pupal exuvia of a Philiris , presumed to be Philiris petriei , was located in the Whiteman Range, New Britain, by the author during January 2013 on a small plant of Litsea species. Some months later two eggs were located on the same plant and one was sleeved. Both eggs hatched after some days and developed very slowly through the winter months, reaching final instar during August. One of the larva pupated in late September (larval duration 121 days), emerging in early Oct (pupal duration 14 days). Owing to the lack of florescence (flowers and/or fruit), it has not been possible to identify the Litsea species on which the new species feeds, although similarly to Litsea callophyllantha , it appears to grow very slowly and remain as a sapling for years until an opening in the canopy creates an opportunity for the plant to flourish. The food plant of Philiris petriei is very different from the large leaved Litsea guppyi (F. Muell) F. Muell. Ex Forman., the food plant of Philiris siassi Sands, 1979 ( Müller 2002), which flies in the same habitats as Philiris petriei .

The early stages of both Philiris harterti (Figs 93-96) and Philiris petriei (Figs 88-92) are exceptionally well camouflaged on their foodplant, with those of Philiris petriei even more so than the larvae and pupae of Philiris harterti . The early stages are quite distinct between the two taxa, with the pupa of the new species being much less speckled and with more irregular dark patches than in Philiris harterti . The anterior of the pupa of Philiris petriei lacks the very long setae present in Philiris harterti . The mature larvae of the two taxa differ in that that of Philiris petriei is brown while the larva of Philiris harterti is greenish and the setae are much coarser in the latter species. The early stages of Philiris petriei are described below.

Egg (Not illustrated): Approximately 0.5 mm diameter, white, domed, wider than high, intricately sculptured. Similar to those of other Philiris taxa examined.

First Instar (Not illustrated): c. 1.0 mm long, grass green, with long translucent setae.

Second Instar (Fig. 88): c. 4 mm long, 1.5 mm wide, deep green centrally with light green-brown margins, with long translucent setae.

Third Instar (Not illustrated): c. 7.0 mm in length, 1.5 mm wide, similar to second instar but with lateral margin brown rather than green.

Fourth Instar (Fig. 89): c. 10.0 mm in length, 2.5 mm wide, flattened, flanged laterally, centrally deep green with broad light brown margins, finely speckled with white, with long light brown setae on margins.

Final Instar (Fig. 90): c. 15 mm in length, 4.5 mm wide, flattened, flanged laterally, light red-brown, weakly speckled with white, with long light brown setae on margins.

Pupa (Figs 91, 92): 13 mm in length, 4.5 mm wide, light brown with dark brown irregular mottled patches, particularly on eyes and surrounding the wing cases, fine short setae (<1 mm long) anteriorly and on abdomen.

Similarly to the larva of Philiris harterti , the first two instars feed on the underside epidermis of the leaf of the food plant, sheltering concealed within these shallow depressions which become feeding scars on the foliage. The third instar larvae chews troughs from the stem of the food plant, within which it eventually rests, progressively increasing the size of the trough to accommodate the sheltering larva. At this stage the larva also chews right through the leaf, creating holes. Eventually, the larva pupates within the trough, where it is remarkably well concealed.

Remarks.

Philiris petriei may possibly be restricted to the island of New Britain within the Bismarck Archipelago. Substantial surveying of pristine habitats by the author in New Ireland from sea level to the highest elevations has not yielded any specimens of this taxon. The insect may also be confined to upland habitats, with all specimens taken above 950 m. It appears to be a rather rare species, possibly due to the scarcity of its larval food plant.