Philonthus hanskii, Rougemont, 2016

Rougemont, G. de, 2016, New Bornean Staphylinidae (Coleoptera), Linzer biologische Beiträge 48 (1), pp. 559-572 : 560-561

Philonthus hanskii nov.sp. (Fig. 1)

Philonthus sp. cf. cyaneoviolaceus BERNH. HANSKI & HAMMOND, 1986: 18 .

3 Holotype: SARAWAK, Gunung Mulu N.P., Camp 4 tube 212, 2011 I. Hanski [ NHML] ; 100 paratypes: many labelled as above, but camp number either 3 or 4, and tube numbers different; others are labelled: Borneo, Gunung Mulu, I. Hanski, Camp 4, 1700-2300 ‘240’.

Other mounted specimens are not designated paratypes. Fragments and incomplete bodies of many other individuals were found in Hanski’s 2011 trap samples from high altitude sites on Gunung Mulu; altogether 195 specimens were collected in 1978 and about 155 specimens in 2011. [Holotype and 82 paratypes in NHML; 5 paratypes in OUMNH; 10 paratypes in CRO, 3 paratypes in LML]; 1♀: [on pink label]: B. N. BORNEO nr. Kinabalu, Tenompok Pass 4200’, 18-3-1929 / Philonthus cyaneoviolaceus Bnh. / Ex F.M.S. Museum BM 1955-354 / Philonthus hanskii Rgmt det. 2015 G. de Rougemont [NHML]; 2♀♀: [on pink label]: B.N.BORNEO, Mt. Kinabalu, Lumu Lumu, 5.500 ft., 15-4-1929 / Ex F.M.S. Museum BM 1955-354 [NHML]; 13: N. BORNEO Mt. Kinabalu / Ulu Mentaki, 8-10.iv. 1964, 900 ft / Royal Soc. Exped. Coll. S. Kueh, BM 1964-250 [NHML].

D e s c r i p t i o n: length: 6.8-10 mm. Holotype: head and pronotum black with a strong brassy reflex, scutellum black, elytra with a strong purple reflex, abdomen black, very shiny; mouthparts, antennae and legs black. All dorsal surfaces glossy, devoid of microscupture. Head subquadrate, the sides retracted towards bas but posterior angles well marked; eyes large, almost twice as long as temples; puncturation sparse, consisting of a single large setiferous puncture on anterior margins of eyes, a pair of smaller frontal punctures between these, and 6-7 punctures near and behind posterior margins of eyes. Antennae long and stout, segment III a little longer than II, IV shorter and broader than III, VI-X distinctly transverse, Pronotum slightly elongate, the sides a little retracted anteriad, discal series of 4+1 punctures, with four punctures in anterior half between discal series and lateral margins, not counting the large lateral setiferous puncture situated on lateral border and bearing a very long black seta; in addition the posterior margin bears a few small punctures. Elytra as long as broad, the sides a little dilated posteriad; puncturation fairly fine and sparse, the interstices much greater than diameter of punctures; pubescence and setae black, the sides with 5-6 longer setae, the outer half of posterior margins with 4-5 conspicuously longer setae in addition to short pubescence. Abdominal tergites very glossy, very finely and sparsely punctured, each tergite with an unbroken row of small punctures along posterior border, the disc of tergites with only a few scattered fine punctures. First segment of metatarsi broader but scarcely longer than second, the fifth slender and twice as long as fourth.

M a l e: protarsi dilated; abdominal sternite VIII with a small triangular emargination extending 1/4 th the length of sternite; aedoeagus (Figs 1 al, 1av) small (1.2 mm), narrow, the median lobe narrow and tapering to an acute apex; paramere (Fig. 1p) narrow and short, the apex truncate and bearing a solid black transverse callosity that appears to be fused peg setae and bearing four small fine pale apical setae.

V a r i a b i l i t y the colour pattern of most specimens is as described above, but in some others the head and pronotum are bronze or greenish, and/or the elytra may be blue instead of purple, a mixture of both colours, or greenish.

The four specimens recorded from Mt. Kinabalu vary in size and colour; the two females from Lumu Lumu are 10 mm long; one has blue and the other purple elytra; the other two specimens measure just under 7 mm, and the (blue) metallic reflex of the male is weaker than in the other specimens. The paramere of this specimen differs slightly from those of the Mulu ones, being distinctly dilated apically, and the truncate tip is concave. This difference may be a function of allopatry of the two populations, but in the absence of more material is not sufficient to warrant the designation of a separate taxon for the Kinabalu form.

The colour of P. cyaneoviolaceus also varies; the type is described by Bernhauer as having the same colour pattern as that of the holotype of P. hanski as described above; in the specimen I examined the head and elytra are dark metallic green, the latter with irregular brassy or coppery reflexes, the pronotum dark metallic blue.

P. hanskii nov.sp. differs from P. cyaneoviolaceus as follows: averagely smaller; head broader, more quadrate, with more pronounced posterior angles; antennae shorter, with segments VIII-X obconical, distally as wide as long or slightly transverse (elongate in cyaneoviolaceus); pronotum shorter, widest at about middle, whereas it is more rectilinear-sided and widest behind middle in cyaneoviolaceus); punctures of pronotal discal series of 1 + 4 finer and more regularly spaced. The aedoeagus is much smaller and narrower, the short paramere devoid of marginal peg setae; in P. cyaneoviolaceus the paramere is large, broadly lanceolate, its apex almost reaching the tip of the median lobe and abruptly recurved towards the ventral face of the median lobe, each margin furnished with about 18 closely and regularly spaced sensory peg setae extending from apex for over half the distance to base.

In spite of the enormous volume of staphylinid material collected in Borneo in the last three decades and extensive trapping programmes, apart from the four specimens of a slightly different form from Mount Kinabalu, this species has only been found in Gunung Mulu N.P. where it is restricted to and common at high altitude (Hanski’s "camp 3" covers trap sites situated between 1000 and 1650 m altitude; "camp 4" sites between 1700 and 2300 m); all specimens were collected in dung- or carrion-baited traps.